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1
Badali, Matthew, and Anton Zilman. "Effects of niche overlap on coexistence, fixation and invasion in a population of two interacting species." Royal Society Open Science 7, no. 2 (2020): 192181. http://dx.doi.org/10.1098/rsos.192181.
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Synergistic and antagonistic interactions in multi-species populations—such as resource sharing and competition—result in remarkably diverse behaviours in populations of interacting cells, such as in soil or human microbiomes, or clonal competition in cancer. The degree of inter- and intra-specific interaction can often be quantified through the notion of an ecological ‘niche’. Typically, weakly interacting species that occupy largely distinct niches result in stable mixed populations, while strong interactions and competition for the same niche result in rapid extinctions of some species and fixations of others. We investigate the transition of a deterministically stable mixed population to a stochasticity-induced fixation as a function of the niche overlap between the two species. We also investigate the effect of the niche overlap on the population stability with respect to external invasions. Our results have important implications for a number of experimental systems.
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Allgeier, Jacob E., Thomas C. Adam, and Deron E. Burkepile. "The importance of individual and species-level traits for trophic niches among herbivorous coral reef fishes." Proceedings of the Royal Society B: Biological Sciences 284, no. 1856 (2017): 20170307. http://dx.doi.org/10.1098/rspb.2017.0307.
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Resolving how species compete and coexist within ecological communities represents a long-standing challenge in ecology. Research efforts have focused on two predominant mechanisms of species coexistence: complementarity and redundancy. But findings also support an alternative hypothesis that within-species variation may be critical for coexistence. Our study focuses on nine closely related and ecologically similar coral reef fish species to test the importance of individual- versus species-level traits in determining the size of dietary, foraging substrate, and behavioural interaction niches. Specifically, we asked: (i) what level of biological organization best describes individual-level niches? and (ii) how are herbivore community niches partitioned among species, and are niche widths driven by species- or individual-level traits? Dietary and foraging substrate niche widths were best described by species identity, but no level of taxonomy explained behavioural interactions. All three niches were dominated by only a few species, contrasting expectations of niche complementarity. Species- and individual-level traits strongly drove foraging substrate and behavioural niches, respectively, whereas the dietary niche was described by both. Our findings underscored the importance of species-level traits for community-level niches, but highlight that individual-level trait variation within a select few species may be a key driver of the overall size of niches.
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Mauretti, Arianna, Sergio Spaans, Noortje A. M. Bax, Cecilia Sahlgren, and Carlijn V. C. Bouten. "Cardiac Progenitor Cells and the Interplay with Their Microenvironment." Stem Cells International 2017 (2017): 1–20. http://dx.doi.org/10.1155/2017/7471582.
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The microenvironment plays a crucial role in the behavior of stem and progenitor cells. In the heart, cardiac progenitor cells (CPCs) reside in specific niches, characterized by key components that are altered in response to a myocardial infarction. To date, there is a lack of knowledge on these niches and on the CPC interplay with the niche components. Insight into these complex interactions and into the influence of microenvironmental factors on CPCs can be used to promote the regenerative potential of these cells. In this review, we discuss cardiac resident progenitor cells and their regenerative potential and provide an overview of the interactions of CPCs with the key elements of their niche. We focus on the interaction between CPCs and supporting cells, extracellular matrix, mechanical stimuli, and soluble factors. Finally, we describe novel approaches to modulate the CPC niche that can represent the next step in recreating an optimal CPC microenvironment and thereby improve their regeneration capacity.
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Schirmer, Annika, Julia Hoffmann, Jana A. Eccard, and Melanie Dammhahn. "My niche: individual spatial niche specialization affects within- and between-species interactions." Proceedings of the Royal Society B: Biological Sciences 287, no. 1918 (2020): 20192211. http://dx.doi.org/10.1098/rspb.2019.2211.
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Intraspecific trait variation is an important determinant of fundamental ecological interactions. Many of these interactions are mediated by behaviour. Therefore, interindividual differences in behaviour should contribute to individual niche specialization. Comparable with variation in morphological traits, behavioural differentiation between individuals should limit similarity among competitors and thus act as a mechanism maintaining within-species variation in ecological niches and facilitating species coexistence. Here, we aimed to test whether interindividual differences in boldness covary with spatial interactions within and between two ecologically similar, co-occurring rodent species ( Myodes glareolus , Apodemus agrarius ). In five subpopulations in northeast Germany, we quantified individual differences in boldness via repeated standardized tests and spatial interaction patterns via capture–mark–recapture ( n = 126) and automated VHF telemetry ( n = 36). We found that boldness varied with space use in both species. Individuals of the same population occupied different spatial niches, which resulted in non-random patterns of within- and between-species spatial interactions. Behavioural types mainly differed in the relative importance of intra- versus interspecific competition. Within-species variation along this competition gradient could contribute to maintaining individual niche specialization. Moreover, behavioural differentiation between individuals limits similarity among competitors, which might facilitate the coexistence of functionally equivalent species and, thus, affect community dynamics and local biodiversity.
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Costa-Pereira, Raul, Márcio S. Araújo, Franco L. Souza, and Travis Ingram. "Competition and resource breadth shape niche variation and overlap in multiple trophic dimensions." Proceedings of the Royal Society B: Biological Sciences 286, no. 1902 (2019): 20190369. http://dx.doi.org/10.1098/rspb.2019.0369.
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Competition plays a central role in the maintenance of biodiversity. A backbone of classic niche theory is that local coexistence of competitors is favoured by the contraction or divergence of species' niches. However, this effect should depend on the diversity of resources available in the local environment, particularly when resources vary in multiple ecological dimensions. Here, we investigated how available resource breadth (i.e. prey diversity) and competition together shape multidimensional niche variation (between and within individuals) and interspecific niche overlap in 42 populations of congeneric tropical frog species. We modelled realized niches in two key trophic dimensions (prey size and carbon stable isotopes) and sampled available food resources to quantify two-dimensional resource breadth. We found a 14-fold variation in multidimensional population niche width across populations, most of which was accounted for by within-individual diet variation. This striking variation was predicted by an interaction whereby individual niche breadth increased with resource breadth and decreased with the number of congeneric competitors. These ecological gradients also interact to influence the degree of niche overlap between species, which surprisingly decreased with population total niche width, providing novel insights on how similar species can coexist in local communities. Together, our results emphasize that patterns of exploitation of resources in multiple dimensions are driven by both competitive interactions and extrinsic factors such as local resource breadth.
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Richards, Greg. "Rethinking niche tourism: The example of backpacking." Croatian Regional Development Journal 2, no. 1 (2021): 1–10. http://dx.doi.org/10.2478/crdj-2021-0004.
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Abstract This conceptual paper re-evaluates the concept of niches in tourism markets. As many regions are now attempting to address niche markets in tourism as a development strategy, understanding of the dynamics of niche markets is crucial. Current approaches are often limited to seeing niche markets as simple subsectors of larger consumer markets. We argue for a broader view of market niches as forms of social rituals involving both consumers and producers with a mutual focus of attention. Based on the work of Randall Collins we examine how interaction rituals are produced and maintained, and how these are also reflected in niche markets, such as backpacking. We illustrate the how backpacking produces a mutual focus of attention and boundaries to outsiders, helping to sustain the niche over the longer term. This analysis has implications for producers hoping to tap into niche markets, as they too need to become part of the niche community.
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Adiloglu, Ali Kudret. "The Interaction of Diet, Microbiota, and Antimicrobial Peptides in the Gastrointestinal Ecosystem." Niche Journal 3, no. 2 (2016): 28–32. http://dx.doi.org/10.5152/niche.2016.218.
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Setiawan, Erik, Agus Priyono Kartono, and Burhanuddin Masy'ud. "Interspesific Interactions among Three Species of Deer in Captivity." Media Konservasi 23, no. 2 (2018): 144–52. https://doi.org/10.29244/medkon.23.2.144-152.
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In natural habitats, every organism including wildlife interacts with another individuals both in one species (intraspecific) and with other species of (interspecific), and each interaction can be positive, negative or neutral. In deer captive breeding of Cariu Bogor, three species of deer were bred namely bawean deer (Axis kuhlii), timor deer (deer timorensis) and spotted deer (Axis axis), but so far the interspecific interaction among the three species has not been known comprehensively. This research was conducted to aim (1) calculate the time usage for activities, (2) calculate the period of space usage and homerange width of each deer species in the captive area, (3) niche breadth and the scores of niche overlap , (4) the characteristic of interspecific interactions, and (5) the presences or absences of cross-breeding among the three deer species that are bred. Data was collected through field observations by recording activity period, time and place of deer presence simultaneously and the attitude or response given by individuals of different deer species, movement mapping and space utilization in four types of habitat also the types of plants consumed, then analyzed with several methods such as Chi-square test, Levins and Hulbert niche width and Morisita index. The results showed that the three deer species had different time and space usage. Most of the time is used for eating and resting in the grasslands. The homerange area of the three deer species are different, where the bawean deer have a wider homerange (3.6 ha) than spotted deer (2.6 ha) and timor deer (2.2 ha). The results of niche breadth calculation showed that the bawean deer had wider niche (4.3) than the spotted deer (2.1) and timor deer (1.6), with the percentage of niches overlap by Morisita index between bawean deer and spotted deer is 95%, between bawean deer and timor deer is 70.5% and between spotted deer and timor deer is 96.6%. Interspecific interaction among the three species is neutral (zero), and there is no crossbreeding between the three species of deer that are bred simultaneously in one breeding area. Keywords: captive breeding, crossbreeding, interspecific interaction, niche overlapping, three deer species
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Khattab, Shaimaa, Manal El Sorady, Ashraf El-Ghandour, Giuseppe Visani, and Pier Paolo Piccaluga. "Hematopoietic and leukemic stem cells homeostasis: the role of bone marrow niche." Exploration of Targeted Anti-tumor Therapy 5, no. 5 (2024): 1027–55. http://dx.doi.org/10.37349/etat.2024.00262.
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The bone marrow microenvironment (BMM) has highly specialized anatomical characteristics that provide a sanctuary place for hematopoietic stem cells (HSCs) that allow appropriate proliferation, maintenance, and self-renewal capacity. Several cell types contribute to the constitution and function of the bone marrow niche. Interestingly, uncovering the secrets of BMM and its interaction with HSCs in health paved the road for research aiming at better understanding the concept of leukemic stem cells (LSCs) and their altered niche. In fact, they share many signals that are responsible for interactions between LSCs and the bone marrow niche, due to several biological similarities between LSCs and HSCs. On the other hand, LSCs differ from HSCs in their abnormal activation of important signaling pathways that regulate survival, proliferation, drug resistance, invasion, and spread. Targeting these altered niches can help in better treatment choices for hematological malignancies and bone marrow disorders in general and acute myeloid leukemia (AML) in particular. Moreover, targeting those niches may help in decreasing the emergence of drug resistance and lower the relapse rate. In this article, the authors reviewed the most recent literature on bone marrow niches and their relations with either normal HSCs and AML cells/LSC, by focusing on pathogenetic and therapeutic implications.
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Kuek, Vincent, Anastasia M. Hughes, Rishi S. Kotecha, and Laurence C. Cheung. "Therapeutic Targeting of the Leukaemia Microenvironment." International Journal of Molecular Sciences 22, no. 13 (2021): 6888. http://dx.doi.org/10.3390/ijms22136888.
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In recent decades, the conduct of uniform prospective clinical trials has led to improved remission rates and survival for patients with acute myeloid leukaemia and acute lymphoblastic leukaemia. However, high-risk patients continue to have inferior outcomes, where chemoresistance and relapse are common due to the survival mechanisms utilised by leukaemic cells. One such mechanism is through hijacking of the bone marrow microenvironment, where healthy haematopoietic machinery is transformed or remodelled into a hiding ground or “sanctuary” where leukaemic cells can escape chemotherapy-induced cytotoxicity. The bone marrow microenvironment, which consists of endosteal and vascular niches, can support leukaemogenesis through intercellular “crosstalk” with niche cells, including mesenchymal stem cells, endothelial cells, osteoblasts, and osteoclasts. Here, we summarise the regulatory mechanisms associated with leukaemia–bone marrow niche interaction and provide a comprehensive review of the key therapeutics that target CXCL12/CXCR4, Notch, Wnt/b-catenin, and hypoxia-related signalling pathways within the leukaemic niches and agents involved in remodelling of niche bone and vasculature. From a therapeutic perspective, targeting these cellular interactions is an exciting novel strategy for enhancing treatment efficacy, and further clinical application has significant potential to improve the outcome of patients with leukaemia.
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Gottfried, Iwona, Bartosz Borczyk, and Tomasz Gottfried. "Snakes use microhabitats created by the great capricorn beetle Cerambyx cerdo in southwest Poland." Herpetozoa 32 (June 12, 2019): 133–35. http://dx.doi.org/10.3897/herpetozoa.32.e35824.
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Niche engineering is considered one of the most important interspecific interactions that shape ecosystems, but this kind of interaction network has not been sufficiently studied so far. Here we present the first observation of grass snake Natrixnatrix in the galleries of Cerambyxcerdo. We recorded three grass snake individuals basking and hiding inside the C.cerdo galleries. We suggest the presence of this beetle species may create new environmental niches and improve habitat quality for snakes and other vertebrates.
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Moncayo-Estrada, Rodrigo, Owen T. Lind, and Carlos Escalera-Gallardo. "Trophic interactions among sympatric zooplanktivorous fish species in volume change conditions in a large, shallow, tropical lake." Neotropical Ichthyology 9, no. 1 (2011): 169–76. http://dx.doi.org/10.1590/s1679-62252011005000003.
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Significant reductions in the water volume of shallow lakes impose a restriction on species segregation promoting more interactions in the trophic relationships. The diets of three closely related zooplanktivorous silversides belonging to the Atherinopsidae species flock of lake Chapala , Mexico, were analyzed at two sites (Chirostoma jordani, C. labarcae, and C. consocium). Diets were described in critical shallow (August 2000) and volume recovery conditions (August 2005). Diets included mainly cladocerans (Bosmina, Ceriodaphnia, and Daphnia) and copepods (Cyclops). A significant difference in diets was detected when comparing years (MRPP analysis, A = 0.22, p < 0.0001) and sites at different years (MRPP analysis, A = 0.17, p = 0.004). According to niche breadth mean values, species were classified as specialized and intermediate feeders. In shallow conditions, the small range of niche breadth (1.72 to 3.64) and high diet overlap values (D = 0.64, L = 8.62) indicated a high potential for interspecific exploitative interaction. When the lake volume recovered, an increase in the niche breadth range (1.04 to 4.96) and low niche overlap values (D = 0.53, L = 2.32) indicated a reduction of the species interaction. The Mann-Whitney U-test supported this pattern by showing a significant difference between years for niche overlap (p = 0.006). The increased interaction during the low volume suggests alternative segregation in life-history variations and other niche dimensions such as spatial or temporal distribution.
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Gottfried, Iwona, Bartosz Borczyk, and Tomasz Gottfried. "Snakes use microhabitats created by the great capricorn beetle Cerambyx cerdo in southwest Poland." Herpetozoa 32, no. () (2019): 133–35. https://doi.org/10.3897/herpetozoa.32.e35824.
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Niche engineering is considered one of the most important interspecific interactions that shape ecosystems, but this kind of interaction network has not been sufficiently studied so far. Here we present the first observation of grass snake Natrix natrix in the galleries of Cerambyx cerdo. We recorded three grass snake individuals basking and hiding inside the C. cerdo galleries. We suggest the presence of this beetle species may create new environmental niches and improve habitat quality for snakes and other vertebrates.
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NOWNES, ANTHONY J. "Policy Conflict and the Structure of Interest Communities." American Politics Quarterly 28, no. 3 (2000): 309–27. http://dx.doi.org/10.1177/1532673x00028003002.
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Drawing on data from a survey of 595 state interest representatives this article asks: Is policy conflict widespread in state interest communities or is it rare due to the isolation of interest organizations in relatively placid niches? Two contending perspectives frame the current debate on this issue. Whereas Browne maintains that balkanization characterizes interest communities, Salisbury and his colleagues suggest that many policy domains feature substantial intergroup interaction, conflict, and cooperation. In all, the data witness relatively high levels of conflict among groups and between groups and other political actors and thus confound the expectations of Browne's niche theory. Nevertheless, the data do not invalidate niche theory. Rather, they suggest that some policy domains are more likely to be characterized by niche politics than others and that the federal government provides more incentives than state governments for groups to seek niches.
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Bueno, Raquel de Oliveira, Thais Bastos Zanata, and Isabela Galarda Varassin. "Niche partitioning between hummingbirds and well-matched flowers is independent of hummingbird traits." Journal of Tropical Ecology 37, no. 4 (2021): 193–99. http://dx.doi.org/10.1017/s026646742100033x.
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AbstractAmong nectarivorous birds, the highest niche partitioning occurs between hummingbirds and plants. Although hummingbirds tend to visit morphologically well-matched resources, as ornithophilous species, they can also visit flowers with other traits. Here, we investigated whether the niche partitioning in hummingbird-plant interactions is also observed with ornithophilous species only. We also explored if hummingbird traits predicted resources use. We recorded a plant-ornithophilous species network in a semi-deciduous forest in Brazil. We quantified interaction partitioning through network connectance, complementary specialisation, and modularity. The influence of hummingbirds’ traits into their visits was investigated through methods of functional ecology and ecological networks. We recorded 948 interactions between nine hummingbirds and seven ornithophilous plants. We detected similar patterns of niche partitioning between hummingbirds and ornithophilous plants in comparison to networks considering the entire plant community. However, hummingbird species with the most specialised interactions are different from those when the whole system is evaluated. Therefore, we cannot downscale the patterns from one scale to the other. The pattern of interaction with ornithophilous plants was not related to hummingbirds’ traits. Therefore, the coexistence of species with shared traits might be occurring through facilitative and competitive processes, leading to trait mismatching and maintaining niche partitioning among ornithophilous plants.
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Nicol, Jason M., and George G. Ganf. "Water regimes, seedling recruitment and establishment in three wetland plant species." Marine and Freshwater Research 51, no. 4 (2000): 305. http://dx.doi.org/10.1071/mf99147.
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The regeneration niche of three wetland species that co-occur at Bool Lagoon, South Australia, was investigated under nine hydrologic conditions. Typha domingensis grown from seed had the broadest niche requirements; seeds germinated and seedlings were established in all 9 hydrologic regimes, and asexual reproduction occurred in 5 of the 9 regimes. Whether asexual reproduction occurred was dependent upon an interaction between the rate of leaf elongation, the rate of drawdown and whether the leaf was able to broach the water surface. The buoyant nature of seeds and seedlings ofTriglochin procerum allowed it to avoid unfavourable regeneration niches. Melaleuca halmaturorum had a narrow regeneration niche that was confined to wet mud flats. The results are consistent with the changes in the floristic composition of the lagoon.
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Choi, Inpyo, Mira Jeong, and Suk Ran Yoon. "Regulation of hematopoietic stem cell quiescence by TXNIP (36.1)." Journal of Immunology 184, no. 1_Supplement (2010): 36.1. http://dx.doi.org/10.4049/jimmunol.184.supp.36.1.
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Abstract Hematopoietic stem cells (HSCs) are distinct cells that are predominantly located in the bone marrow microenvironment, which is referred to as the niche. HSC quiescence, activation, and mobilization are coordinately regulated in their niche by intrinsic and extrinsic mechanisms. Several genes, including those that encode transcriptional regulators, cell cycle regulatory proteins, tumor suppressors, and proto-oncogenes, intrinsically regulate the balance between HSC quiescence and activation. The vitamin D3 up-regulated protein 1 (VDUP1) is a 397 amino acid residue, 50-kDa protein that belongs to the arrestin family. We hypothesized that VDUP1 plays a pivotal role in controlling HSC cell cycle, migration, and BM niche interactions. The expression of VDUP1 is decreased during HSC activation. In VDUP1-/- mice, the LT-HSC population is decreased and exhausted, and its capacity to repopulate is rapidly lost. The VDUP1 deficiency reduced the osteopontin/integrin β1-mediated interaction between HSCs and the bone marrow niche and impaired homing and retention in the osteoblastic niche, resulting in mobilized HSCs. Thus, we propose that VDUP1 is essential for maintaining HSC quiescence and interactions with the BM niche.
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Robertson, Sarah Y. T., JoAnn S. Roberts, and Sophie X. Deng. "Regulation of Limbal Epithelial Stem Cells: Importance of the Niche." International Journal of Molecular Sciences 22, no. 21 (2021): 11975. http://dx.doi.org/10.3390/ijms222111975.
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Limbal epithelial stem/progenitor cells (LSCs) reside in a niche that contains finely tuned balances of various signaling pathways including Wnt, Notch, BMP, Shh, YAP, and TGFβ. The activation or inhibition of these pathways is frequently dependent on the interactions of LSCs with various niche cell types and extracellular substrates. In addition to receiving molecular signals from growth factors, cytokines, and other soluble molecules, LSCs also respond to their surrounding physical structure via mechanotransduction, interaction with the ECM, and interactions with other cell types. Damage to LSCs or their niche leads to limbal stem cell deficiency (LSCD). The field of LSCD treatment would greatly benefit from an understanding of the molecular regulation of LSCs in vitro and in vivo. This review synthesizes current literature around the niche factors and signaling pathways that influence LSC function. Future development of LSCD therapies should consider all these niche factors to achieve improved long-term restoration of the LSC population.
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Ji, Yue, Paul Kwong-Hang Tam, and Clara Sze-Man Tang. "Roles of Enteric Neural Stem Cell Niche and Enteric Nervous System Development in Hirschsprung Disease." International Journal of Molecular Sciences 22, no. 18 (2021): 9659. http://dx.doi.org/10.3390/ijms22189659.
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The development of the enteric nervous system (ENS) is highly modulated by the synchronized interaction between the enteric neural crest cells (ENCCs) and the neural stem cell niche comprising the gut microenvironment. Genetic defects dysregulating the cellular behaviour(s) of the ENCCs result in incomplete innervation and hence ENS dysfunction. Hirschsprung disease (HSCR) is a rare complex neurocristopathy in which the enteric neural crest-derived cells fail to colonize the distal colon. In addition to ENS defects, increasing evidence suggests that HSCR patients may have intrinsic defects in the niche impairing the extracellular matrix (ECM)-cell interaction and/or dysregulating the cellular niche factors necessary for controlling stem cell behaviour. The niche defects in patients may compromise the regenerative capacity of the stem cell-based therapy and advocate for drug- and niche-based therapies as complementary therapeutic strategies to alleviate/enhance niche-cell interaction. Here, we provide a summary of the current understandings of the role of the enteric neural stem cell niche in modulating the development of the ENS and in the pathogenesis of HSCR. Deciphering the contribution of the niche to HSCR may provide important implications to the development of regenerative medicine for HSCR.
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Hosokawa, Kentaro, Fumio Arai, Hiroki Yoshihara, et al. "Reactive Oxygen Species Control Hematopoietic Stem Cell-Niche Interaction through the Regulation of N-Cadherin." Blood 108, no. 11 (2006): 86. http://dx.doi.org/10.1182/blood.v108.11.86.86.
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Abstract Interaction of tissue stem cells with their particular microenvironments, known as stem cell niches, is critical for maintaining the stem cell properties, including self-renewal capacity and the ability of differentiation into single or multiple lineages. We previously reported that the regulation of reactive oxygen species (ROS) is critical for the self-renewal activity of HSCs (Ito et al., Nature 2004, Ito et al., Nat Med 2006). Accumulation of ROS in HSCs induced defects in repopulating ability and in maintenance of quiescence through the activation of p38MAPK and p16Ink4a, indicating that the oxidative stress contributes to exhaustion of the stem cell population. From these findings, we hypothesized that loss of quiescence was associated with the impaired HSC-niche interaction. Oxidative stress may affect not only intrinsic function of HSC but the interaction between HSCs and their niche. In this study, we investigated the effects of ROS in the interaction of HSC with osteoblastic niche. We have found that the side-population (SP) in c-Kit+Sca-1+ Lin− (KSL) fraction was the quiescent HSCs in the osteoblastic niche and KSL-SP cells expressed N-cadherin (NCAD) (Arai et al., Cell 2004), and NCAD mediated cell adhesion induced quiescence of HSCs. Then we analyzed the role of ROS in the maintenance of NCAD-mediated cell-cell adhesion and detachment of HSCs from the niche under the myelosuppressive condition. Administration of 5-FU to mice decreases the dividing cells (non-SP fraction), but not quiescent cells (SP fraction) in BM on day 2. On day 6, HSC population was shifted from SP to non-SP fraction. This event might be associated with the cell cycle activation and detachment of HSCs from the niche. We found that 5-FU treatment transiently increased a level of intracellular ROS in HSCs and downregulated the expression of NCAD in HSCs. Administration of anti-oxidant, N-Acetyl Cysteine (NAC), in 5-FU treated mice maintained NCAD expression in HSCs, suggesting that increased ROS suppressed the expression of NCAD in HSCs. In addition, NAC treatment inhibited the transition of HSCs from SP to non-SP fraction on day 6. Moreover, 5-FU induced upregulation of G-CSFR and Flt3 expression in HSCs on day 2, while NAC treatment inhibited the expressions of growth factor receptors. These data indicated that intracellular ROS was a trigger for the detachment of HSCs from the niche, and inhibition of oxidative stress in HSCs by ant-oxidant preserved NCAD-mediated cell adhesion and blocked cell cycle activation after myelosuppression. Furthermore, these data led us the possibility that normal quiescent HSCs maintains low oxidative stress by existing in the low oxygen environment. To confirm this hypothesis, we evaluated the redox status of fractionated hematopoietic cells (Lin+, Lin−, KSL-non SP, and KSL-SP) by hypoxic marker pimonidazole. And we confirmed that &gt;80 % of KSL-SP cells were pimonidazole positive, suggesting that quiescent HSCs resided in the hypoxic niche. Altogether, our data suggest that regulation of oxidative stress is critical for the interaction between HSCs and BM niche. And osteoblastic niche maintains HSCs in low oxidative stress.
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Ho, Ivy A. W., and Winston S. N. Shim. "Contribution of the Microenvironmental Niche to Glioblastoma Heterogeneity." BioMed Research International 2017 (2017): 1–13. http://dx.doi.org/10.1155/2017/9634172.
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Glioblastoma is the most aggressive cancer of the brain. The dismal prognosis is largely attributed to the heterogeneous nature of the tumor, which in addition to intrinsic molecular and genetic changes is also influenced by the microenvironmental niche in which the glioma cells reside. The cancer stem cells (CSCs) hypothesis suggests that all cancers arise from CSCs that possess the ability to self-renew and initiate tumor formation. CSCs reside in specialized niches where interaction with the microenvironment regulates their stem cell behavior. The reciprocal interaction between glioma stem cells (GSCs) and cells from the microenvironment, such as endothelial cells, immune cells, and other parenchymal cells, may also promote angiogenesis, invasion, proliferation, and stemness of the GSCs and be likely to have an underappreciated role in their responsiveness to therapy. This crosstalk may also promote molecular transition of GSCs. Hence the inherent plasticity of GSCs can be seen as an adaptive response, changing according to the signaling cue from the niche. Given the association of GSCs with tumor recurrence and treatment sensitivity, understanding this bidirectional crosstalk between GSCs and its niche may provide a framework to identify more effective therapeutic targets and improve treatment outcome.
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Wang, Chaoyu, Chen Tian, and Yizhuo Zhang. "The Interaction Between Niche and Hematopoietic Stem Cells." Indian Journal of Hematology and Blood Transfusion 32, no. 4 (2016): 377–82. http://dx.doi.org/10.1007/s12288-016-0639-1.
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Dong, Ruochen, Hua Li, Xi He, et al. "Characterization of Multicellular Niches Supporting Hematopoietic Stem Cells within Distinct Zones." Blood 144, Supplement 1 (2024): 1306. https://doi.org/10.1182/blood-2024-208450.
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Hematopoietic stem cells (HSCs) possess remarkable self-renewal abilities and multilineage potential, ensuring a lifelong supply of both HSCs and their progeny. In the adult bone marrow (BM), it has been proposed that HSCs reside within a physically confined microenvironment or niche. However, previous studies primarily focused on single-cell-based niche models, yielding valuable yet sometimes conflicting findings. In this report, we identify two distinct niches in the fetal liver (FL): the portal-vessel (PV) niche and the sinusoidal niche. Each of these niches has unique features that regulate the quiescence or differentiation of FL-HSCs. We also present evidence suggesting that distinct niches exist in the bone marrow, playing a role in maintaining BM-HSCs. We first introduced two spatial transcriptomic methods, Slide-seq and 10x Visium, in our study of mouse FL, as FL is the primary hematopoietic site during the fetal stage. The data revealed the detailed distribution and transcriptomics of HSCs and potential niche cells, including hepatoblasts, endothelial cells, macrophages, megakaryocytes, and mesenchymal stromal cells (MSCs) in the mouse FL. Interestingly, we found that MSCs and hepatoblasts were characterized by enriched N-cadherin expression (N-cad+), with N-cad+ MSCs being particularly abundant in the portal vessel area. Importantly, the majority of FL-HSCs were found in close proximity to N-cad+ MSCs and endothelial cells, indicating that N-cad+ MSCs and endothelial cells play a supportive role in HSC maintenance. Subsequent CellPhoneDB (CPDB) analysis revealed an enriched Cxcl12-Cxcr4 interaction between N-cad+ MSCs and FL-HSCs. We then generated an N-cadCreER; Cxcl12 mouse model to conditionally knock out the well-studied niche factor, Cxcl12, in N-cad+ cells. Remarkably, deletion of Cxcl12 through N-cadCreERT induction resulted in the expansion of FL-HSCs with a myeloid bias. Slide-seq further showed that Cxcl12 deletion via N-cadCreERT induction led to the repositioning of FL-HSCs from the PV region, which is enriched with MSCs, to the hepatic sinusoidal region, which lacks MSCs. These findings suggest the existence of two distinct niches in the FL: the PV niche, which maintains quiescent and multipotential FL-HSCs, and the sinusoidal niche, which supports proliferative FL-HSCs biased towards myeloid lineages. We then investigated adult bone marrow niches. We transplanted mouse bone marrow HSCs from RFP+ mice into recipient mice with either a wild-type phenotype (WT) or with Cxcl12 deleted from N-cad+ cells (cKO). After 8 weeks, femurs from both groups were collected for immunofluorescence (IF) staining of RFP to determine the distribution of transplanted RFP+ donor cells. Intriguingly, the distribution of donor-derived RFP+ HSPCs was significantly enriched in the trabecular bone area (TBA) in WT recipients. In contrast, in cKO recipients, the RFP+ cells were significantly more prevalent in the central marrow (CM). Cell cycle analysis of donor-derived RFP+ LSK cells showed significantly increased proliferation in cKO recipients compared to WT recipients. Furthermore, in another assay, when the serine protease dipeptidyl peptidase 4 (Dpp4), which truncates Cxcl12 and inhibits its chemotactic activity, was deleted from donor HSPCs, these HSPCs tended to home to the CM in WT recipient mice, suggesting a loss of response to chemotactic signals from the TBA. These findings indicate that distinct niches exist in the bone marrow, with the TBA niche maintaining quiescent HSPCs and the CM niche supporting proliferative HSPCs. To further study the regulatory network in these distinct niches, we are employing spatial transcriptomic techniques, including both 10x Xenium and 10x Visium HD, to reveal the details of HSC and niche cell interactions in each niche. Taken together, our study reports a paradigm-shifting discovery, moving from a single-cell-based niche model to a zonal regulation model that modulates the cell cycle status and other properties of HSPCs. The key distinction lies not in which cell type functions as a niche, but in the different signaling emanating from these multi-cellular niches across various zones. Additionally, we demonstrated that Cxcl12, a reported quiescence inducer of HSPCs, does not directly affect HSC properties. Instead, Cxcl12 serves as a chemoattractant that regulates HSC localization, which in turn determines HSC activities.
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Yu, Zhuo, Wenqian Yang, Xiaoxiao He, et al. "Endothelial cell-derived angiopoietin-like protein 2 supports hematopoietic stem cell activities in bone marrow niches." Blood 139, no. 10 (2022): 1529–40. http://dx.doi.org/10.1182/blood.2021011644.
Full textAbstract:
Abstract Bone marrow niche cells have been reported to fine-tune hematopoietic stem cell (HSC) stemness via direct interaction or secreted components. Nevertheless, how niche cells control HSC activities remains largely unknown. We previously showed that angiopoietin-like protein 2 (ANGPTL2) can support the ex vivo expansion of HSCs by binding to human leukocyte immunoglobulin-like receptor B2. However, how ANGPTL2 from specific niche cell types regulates HSC activities under physiological conditions is still not clear. Herein, we generated an Angptl2-flox/flox transgenic mouse line and conditionally deleted Angptl2 expression in several niche cells, including Cdh5+ or Tie2+ endothelial cells, Prx1+ mesenchymal stem cells, and Pf4+ megakaryocytes, to evaluate its role in the regulation of HSC fate. Interestingly, we demonstrated that only endothelial cell-derived ANGPTL2 and not ANGPTL2 from other niche cell types plays important roles in supporting repopulation capacity, quiescent status, and niche localization. Mechanistically, ANGPTL2 enhances peroxisome-proliferator-activated receptor D (PPARD) expression to transactivate G0s2 to sustain the perinuclear localization of nucleolin to prevent HSCs from entering the cell cycle. These findings reveal that endothelial cell-derived ANGPTL2 serves as a critical niche component to maintain HSC stemness, which may benefit the understanding of stem cell biology in bone marrow niches and the development of a unique strategy for the ex vivo expansion of HSCs.
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Harutyunyan, Karine G., Felix Nwajei, M. Anna Zal, et al. "The Dynamics of Stroma-Leukemia Interaction in the Hypoxic BM Niches in Vivo." Blood 124, no. 21 (2014): 2396. http://dx.doi.org/10.1182/blood.v124.21.2396.2396.
Full textAbstract:
Abstract We and others have previously reported that leukemia progression is associated with vast expansion of the hypoxic niches and stabilization of hypoxia-inducible factor 1 alpha (HIF-1α) in leukemic cells (Frolova et al. Cancer Biol Ther. 2012, 10:858; Benito et al. PLoS One 2011, 6(8); e23108:1). Interactions of leukemia and the bone marrow (BM) microenvironment are known to play a key role in the survival and growth of leukemic cells, and we have shown that HIF-1α stabilization in stromal cells of the microenvironment facilitates leukemia homing and progression (Chen et al. Blood 2012, 119:4971). In this study, we aimed to characterize the time-dependent progression of BM hypoxia involving both leukemia cells and components of the BM niche, using the multiphoton intravital microscopy (MP-IVM) technique. We first generated a transplantable, imageable leukemia model by retrovirally transducing C57Bl6-Ai14 murine BM cells that express red fluorescing tdTomato with the p190-Bcr/Abl oncogene. The resulting p190-Bcr/Abl tdTomato cells caused rapid development of acute lymphocytic leukemia (ALL) in un-irradiated C57Bl6 immunocompetent mice, manifested by infiltration of the spleen, liver, BM within long bones, skull, and central nervous system followed by death within 28 days. Leukemia cells collected from the BM (LBC) of these animals were transplantable into secondary recipients and triggered accelerated ALL development (14-16 days). Time-course analysis of skull and femur bones in the secondary recipients by MP-IVM demonstrated LBC lodging on day 1 after ALL cell injection, followed by rapid accumulation of leukemia cells localized predominantly within the sinusoidal spaces, which were visualized by injecting the vascular fluorescent dye BSA-647 (Fig. 1a). To detect in vivo hypoxia development, we utilized HS680 (HypoxiSense 680), a carbonic anhydrase IX (CAIX)–targeted fluorescent agent that can be used to image overexpression of CAIX, a direct HIF-1α target, in tumors in response to regional hypoxia. C57Bl6 mice were engrafted with 2 x 105 LBC , and HS680 was injected intravenously at serial intervals followed by MP-IVM. In two separate experiments, increased HS680 fluorescence was detected in bone-lining cells in the BM niches of mice harboring ALL on days 8 and 13, but not in their healthy littermates (Fig 1b). To obtain an independent confirmation of hypoxia, additional mice (n=3) at the same stage (day 14) of leukemia development were sacrificed 3 hr after injection of chemical hypoxia probe pimonidazole (Pimo), and hypoxic BM cells that bound the hypoxia probe were detected by immunohistochemistry. Pimo staining demonstrated vastly spread areas of hypoxia that enclosed both leukemia cells and BM niche cells (Fig 1c), consistent with our previously published observations in different leukemia models. In summary, these findings demonstrate rapid development of intra-BM hypoxia that parallels leukemia progression and involves not only leukemia cells, but also BM niche cells. The HS680 probe can detect hypoxia in vivo within niche cells but not in leukemia cells, likely because of differential expression of CAIX. Our ongoing studies will characterize the cellular origin of hypoxic niche cells by utilizing immunohistochemical techniques and Col2.3-GFPemd transgenic mice to visualize osteoblasts. We postulate that the tumor microenvironment altered with hypoxic niche cells will influence leukemia development or responses to therapy. To this end, we have generated mice with conditionally deleted HIF-1α within BM stromal cells and are investigating the differences in leukemia homing, progression, and chemoresistance between these mice and mice whose BM stromal cells express HIF-1a. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.
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Miscopein Saler, Laurine, Virginie Hauser, Mathieu Bartoletti, et al. "The Bric-à-Brac BTB/POZ transcription factors are necessary in niche cells for germline stem cells establishment and homeostasis through control of BMP/DPP signaling in the Drosophila melanogaster ovary." PLOS Genetics 16, no. 11 (2020): e1009128. http://dx.doi.org/10.1371/journal.pgen.1009128.
Full textAbstract:
Many studies have focused on the mechanisms of stem cell maintenance via their interaction with a particular niche or microenvironment in adult tissues, but how formation of a functional niche is initiated, including how stem cells within a niche are established, is less well understood. Adult Drosophila melanogaster ovary Germline Stem Cell (GSC) niches are comprised of somatic cells forming a stack called a Terminal Filament (TF) and associated Cap and Escort Cells (CCs and ECs, respectively), which are in direct contact with GSCs. In the adult ovary, the transcription factor Engrailed is specifically expressed in niche cells where it directly controls expression of the decapentaplegic (dpp) gene encoding a member of the Bone Morphogenetic Protein (BMP) family of secreted signaling molecules, which are key factors for GSC maintenance. In larval ovaries, in response to BMP signaling from newly formed niches, adjacent primordial germ cells become GSCs. The bric-à-brac paralogs (bab1 and bab2) encode BTB/POZ domain-containing transcription factors that are expressed in developing niches of larval ovaries. We show here that their functions are necessary specifically within precursor cells for TF formation during these stages. We also identify a new function for Bab1 and Bab2 within developing niches for GSC establishment in the larval ovary and for robust GSC maintenance in the adult. Moreover, we show that the presence of Bab proteins in niche cells is necessary for activation of transgenes reporting dpp expression as of larval stages in otherwise correctly specified Cap Cells, independently of Engrailed and its paralog Invected (En/Inv). Moreover, strong reduction of engrailed/invected expression during larval stages does not impair TF formation and only partially reduces GSC numbers. In the adult ovary, Bab proteins are also required for dpp reporter expression in CCs. Finally, when bab2 was overexpressed at this stage in somatic cells outside of the niche, there were no detectable levels of ectopic En/Inv, but ectopic expression of a dpp transgene was found in these cells and BMP signaling activation was induced in adjacent germ cells, which produced GSC-like tumors. Together, these results indicate that Bab transcription factors are positive regulators of BMP signaling in niche cells for establishment and homeostasis of GSCs in the Drosophila ovary.
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Malara, Alessandro, Cristian Gruppi, Paola Rebuzzini, Maria Enrica Tira, and Alessandra Balduini. "New Mechanisms of Megakaryocyte-Matrix Interaction within Bone Marrow Environment." Blood 116, no. 21 (2010): 2626. http://dx.doi.org/10.1182/blood.v116.21.2626.2626.
Full textAbstract:
Abstract Abstract 2626 Background. The mechanisms by which megakaryocytes (Mks) proliferate, differentiate, and release platelets into circulation are not well understood. Mk maturation and platelet generation occur in the bone marrow and is consequent to Mk migration from the osteoblastic to the vascular niche, where Mks extend proplatelets and newly generated platelets can be released into the bloodstream. Growing evidence indicate that a complex regulatory mechanism, involving megakaryocyte-matrix interactions, may contribute to the quiescent or permissive microenvironment related to Mk differentiation and maturation within the bone marrow. It has been demonstrated that interactions of primary human Mks with matrices supposed to fill the vascular niche, such as fibrinogen or von Willebrand factor, is able to sustain Mk maturation and proplatelet formation, while type I collagen, in the osteoblastic niche, totally suppresses these events and prevents premature platelet release. The negative regulation of proplatelet formation by type I collagen is mediated by the interaction with integrin alpha2beta1, and involves the Rho/ROCK pathway. Hypothesis. The dynamic interaction of Mks with different extra-cellular matrices, that fill the bone marrow spaces, may orchestrate their maturation in specific sites. Despite the improvement in knowledge of biochemical niche, little is known about the mechanical force that regulate Mk-niche interactions. Therefore, in this work, we correlated activation of signaling cascade with generation of contractile force to understand the influences of bone marrow environment on Mk function. Methodology/Principal Findings. To address this hypothesis, we first demonstrated that human Mks express and synthesize cellular fibronectin (cFN), with a predominance of the EDA isoform, and transglutaminase FXIII-A. Thereafter, we proposed that these two molecules are involved in a new regulatory mechanism of Mk-type I collagen interaction in the osteoblastic niche. We propose that Mk adhesion on type I collagen promotes Mk spreading through a mechanism that involves FN, membrane receptors and FXIII-A activity. This mechanism seemed to be mediated by the exposure of cFN to the cell membrane and maintained by FN polymerization catalyzed by FXIII-A. These data address a new role to FN that, upon specific activation, could be released and thereby modulate Mk interaction with extracellular matrices. In this context FXIII-A catalyzes FN cross-linking at cellular sites, stabilizes FN assembly and promotes the organization of extracellular matrix. Consistently, the same mechanism regulated the assembly of plasma FN (pFN) by adherent Mks to type I collagen. Most importantly, our results demonstrated that only Mks adherent to type I collagen, and not to fibrinogen, were able to promote FN assembly. As a result, we observed that Mk adhesion to type I collagen promoted Mk spreading overtime, while Mks on fibrinogen showed a shortened spreading that was replaced by proplatelet formation in sixteen hours of adhesion. Thus, FN assembly regulate the anchoring of Mks to type I collagen with consequent activation of biochemical signalling and generation of contractile force that may prevent proplatelet formation. Conclusions/Significance. In conclusion, this study provides important new elements in the understanding of the regulatory pathways for Mk-matrix interactions within bone marrow environment. In particular, our results demonstrate that fibronectins and FXIII-A modulate Mk spreading on type I collagen by promoting matrix assembly. This work opens new prospective in the study of illnesses, such as primary myelofibrosis or MYH9-related thrombocytopenia, related to defect of Mk-matrix interactions within the bone marrow environment, whose origin is still matter of debate. Disclosures: No relevant conflicts of interest to declare.
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Souza, Franco, João Rodrigues, Miguel Olalla-Tárraga, José Diniz-Filho, Pablo Martinez, and Ricardo J. Sawaya. "Niche divergence and diversification in South American freshwater turtles of the genus Acanthochelys (Chelidae)." Amphibia-Reptilia 40, no. 4 (2019): 475–85. http://dx.doi.org/10.1163/15685381-20191211.
Full textAbstract:
Abstract Species distribution models (SDMs) are increasingly used to assess how ecological factors shape species distributions and diversification. Chelid turtles represent the richest family of chelonians in South America. Given the distributional disjunction and distinct habitats of four Acanthochelys species, we explored SDMs and niche overlap metrics between species pairs to evaluate the extent to which niche divergence or conservatism may have contributed to their geographic distribution patterns. None of the species pairs presented patterns consistent with niche conservatism suggesting that these species have different environmental requirements. However, when comparing species pairs co-occurring in the same watershed, results were conflicting. Niche divergence detected among Acanthochelys species indicate an interaction between ecological niche preference and geographical barriers for allopatric speciation. This interaction implies that ecological differentiation contributed to the diversification of Acanthochelys side-necked turtles that occur in South American freshwater environments.
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Iwasaki, Hiroko, Fumio Arai, Yoshiaki Kubota, Maria Dahl, and Toshio Suda. "Endothelial protein C receptor–expressing hematopoietic stem cells reside in the perisinusoidal niche in fetal liver." Blood 116, no. 4 (2010): 544–53. http://dx.doi.org/10.1182/blood-2009-08-240903.
Full textAbstract:
Abstract Hematopoietic stem cells (HSCs) are maintained in specialized niches in adult bone marrow. However, niche and HSC maintenance mechanism in fetal liver (FL) still remains unclear. Here, we investigated the niche and the molecular mechanism of HSC maintenance in mouse FL using HSCs expressing endothelial protein C receptor (EPCR). The antiapoptotic effect of activated protein C (APC) on EPCR+ HSCs and the expression of protease-activated receptor 1 (Par-1) mRNA in these cells suggested the involvement of the cytoprotective APC/EPCR/Par-1 pathway in HSC maintenance. Immunohistochemistry revealed that EPCR+ cells were localized adjacent to, or integrated in, the Lyve-1+ sinusoidal network, where APC and extracellular matrix (ECM) are abundant, suggesting that HSCs in FL were maintained in the APC- and ECM-rich perisinusoidal niche. EPCR+ HSCs were in a relatively slow cycling state, consistent with their high expression levels of p57 and p18. Furthermore, the long-term reconstitution activity of EPCR+ HSCs decreased significantly after short culture but not when cocultured with feeder layer of FL-derived Lyve-1+ cells, which suggests that the maintenance of the self-renewal activity of FL HSCs largely depended on the interaction with the perisinusoidal niche. In conclusion, EPCR+ HSCs resided in the perisinusoidal niche in mouse FL.
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Bernasconi, Paolo, and Oscar Borsani. "Targeting Leukemia Stem Cell-Niche Dynamics: A New Challenge in AML Treatment." Journal of Oncology 2019 (August 7, 2019): 1–12. http://dx.doi.org/10.1155/2019/8323592.
Full textAbstract:
One of the most urgent needs in AML is to improve the disease cure rate as relapse still occurs in 60–80% of patients. Recent evidence suggests that dismal clinical outcomes may be improved by a better definition of the tight interaction between the AML cell population and the bone marrow (BM) microenvironment (“the niche”); the latter has been progressively highlighted to have an active role in the disease process. It has now been well established that the leukemic population may misinterpret niche-derived signals and remodel the niche, providing a shelter to AML cells and protecting them from the cytotoxic effects of chemoradiotherapy. Novel imaging technological advances and preclinical disease models have revealed that, due to the finite number of BM niches, leukemic stem cells (LSCs) and normal hematopoietic stem cells (HSCs) compete for the same functional areas. Thus, the removal of LSCs from the BM niche and the promotion of normal HSC engraftment should be the primary goals in antileukemic research. In addition, it is now becoming increasingly clear that AML-niche dynamics are disease stage specific. In AML, the niche has been linked to disease pathogenesis in the preleukemic stage, the niche becomes permissive once leukemic cells are established, and the niche is transformed into a self-reinforcing structure at a later disease stage. These concepts have been fostered by the demonstration that, in unrelated AML types, endosteal vessel loss occurs as a primary AML-induced niche alteration, and additional AML-induced alterations of the niche and normal hematopoiesis evolve focally and in parallel. Obviously, this endosteal vessel loss plays a fundamental role in AML pathogenesis by causing excessive vascular permeability, hypoxia, altered perfusion, and reduced drug delivery. Each of these alterations may be effectively targeted by various therapeutic procedures, but preservation of endosteal vessel integrity might be the best option for any future antileukemic treatment.
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Koyanagi, Anri, Iichiroh Onishi, Karin Muraoka, et al. "Identification of the Factor that Leads Human Mesenchymal Stem Cell Lines into Decellularized Bone." Bioengineering 9, no. 10 (2022): 490. http://dx.doi.org/10.3390/bioengineering9100490.
Full textAbstract:
Hematopoiesis is maintained by the interaction of hematopoietic stem cells (HSCs) and bone marrow mesenchymal stem cells (MSCs) in bone marrow microenvironments, called niches. Certain genetic mutations in MSCs, not HSCs, provoke some hematopoietic neoplasms, such as myelodysplastic syndrome. An in vivo bone marrow niche model using human MSC cell lines with specific genetic mutations and bone scaffolds is necessary to elucidate these interactions and the disease onset. We focused on decellularized bone (DCB) as a useful bone scaffold and attempted to induce human MSCs (UE7T-9 cells) into the DCB. Using the CRISPR activation library, we identified SHC4 upregulation as a candidate factor, with the SHC4 overexpression in UE7T-9 cells activating their migratory ability and upregulating genes to promote hematopoietic cell migration. This is the first study to apply the CRISPR library to engraft cells into decellularized biomaterials. SHC4 overexpression is essential for engrafting UE7T-9 cells into DCB, and it might be the first step toward creating an in vivo human–mouse hybrid bone marrow niche model.
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Smutin, Daniil, Egor Lebedev, Maxim Selitskiy, Nick Panyushev, and Leonid Adonin. "Micro”bee”ota: Honey Bee Normal Microbiota as a Part of Superorganism." Microorganisms 10, no. 12 (2022): 2359. http://dx.doi.org/10.3390/microorganisms10122359.
Full textAbstract:
Honey bees are model organisms for microbiota research. Gut microbiomes are very interesting for surveys due to their simple structure and relationship with hive production. Long-term studies reveal the gut microbiota patterns of various hive members, as well as the functions, sources, and interactions of the majority of its bacteria. But the fungal non-pathogenic part of gut microbiota is almost unexplored, likewise some other related microbiota. Honey bees, as superorganisms, interact with their own microorganisms, the microbial communities of food stores, hive surfaces, and other environments. Understanding microbiota diversity, its transition ways, and hive niche colonization control are necessary for understanding any separate microbiota niche because of their interplay. The long coevolution of bees with the microorganisms populating these niches makes these systems co-dependent, integrated, and stable. Interaction with the environment, hive, and other bees determines caste lifestyle as well as individual microbiota. In this article, we bring together studies on the microbiota of the western honey bee. We show a possible relationship between caste determination and microbiota composition. And what is primary: caste differentiation or microbiota composition?
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Carballo-Morales, Jorge D., Romeo A. Saldaña-Vázquez, Federico Villalobos, and Leonel Herrera-Alsina. "Thermal niche breadth and their relationship with sturnira bat species diversification." Journal of Thermal Biology 117 (June 12, 2023): 103697. https://doi.org/10.5281/zenodo.13477046.
Full textAbstract:
(Uploaded by Plazi for the Bat Literature Project) The interaction between climatic conditions and the ability of organisms to maintain homeostasis regulates the distribution of species on the planet. However, its influence on macroevolutionary dynamics is not well un derstood. It has been suggested that diversification rates will be different in lineages with narrow thermal niches (specialists) to diversification rates in generalist lineages, but the evidence for this is elusive. Here, we tested this hypothesis by using the most diverse (in species richness and geographic range variation) tropical bat genus within the Phyllostomidae family. We estimated the realized thermal niche breadth of Sturnira species from their geographic range and categorized them as generalists, cold specialists, or warm specialists. We compared dy namic evolutionary models that differ in 1) niche breadth evolution, 2) parental niche breadth inheritance, and 3) whether niche breadth evolution is associated with shifts in diversification rates. Our best-performing model indicates that most Sturnira species arose as specialists in warm climates and that over time, their niche breadth broadens, and just a subset of those species becomes specialists in cold environments. We found that the evo lution of realized thermal niche breadth causes fluctuations in per-lineage rates of diversification, where warm specialists boast the highest speciation rates. However, we found no evidence of these changes in niche neither triggering nor being a result of speciation events themselves; this suggests that diversification events in Sturnira could instead depend on allopatric speciation processes such as the development of geographic barriers.
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Carballo-Morales, Jorge D., Romeo A. Saldaña-Vázquez, Federico Villalobos, and Leonel Herrera-Alsina. "Thermal niche breadth and their relationship with sturnira bat species diversification." Journal of Thermal Biology 117 (June 7, 2023): 103697. https://doi.org/10.5281/zenodo.13477046.
Full textAbstract:
(Uploaded by Plazi for the Bat Literature Project) The interaction between climatic conditions and the ability of organisms to maintain homeostasis regulates the distribution of species on the planet. However, its influence on macroevolutionary dynamics is not well un derstood. It has been suggested that diversification rates will be different in lineages with narrow thermal niches (specialists) to diversification rates in generalist lineages, but the evidence for this is elusive. Here, we tested this hypothesis by using the most diverse (in species richness and geographic range variation) tropical bat genus within the Phyllostomidae family. We estimated the realized thermal niche breadth of Sturnira species from their geographic range and categorized them as generalists, cold specialists, or warm specialists. We compared dy namic evolutionary models that differ in 1) niche breadth evolution, 2) parental niche breadth inheritance, and 3) whether niche breadth evolution is associated with shifts in diversification rates. Our best-performing model indicates that most Sturnira species arose as specialists in warm climates and that over time, their niche breadth broadens, and just a subset of those species becomes specialists in cold environments. We found that the evo lution of realized thermal niche breadth causes fluctuations in per-lineage rates of diversification, where warm specialists boast the highest speciation rates. However, we found no evidence of these changes in niche neither triggering nor being a result of speciation events themselves; this suggests that diversification events in Sturnira could instead depend on allopatric speciation processes such as the development of geographic barriers.
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Carballo-Morales, Jorge D., Romeo A. Saldaña-Vázquez, Federico Villalobos, and Leonel Herrera-Alsina. "Thermal niche breadth and their relationship with sturnira bat species diversification." Journal of Thermal Biology 117 (July 3, 2023): 103697. https://doi.org/10.5281/zenodo.13477046.
Full textAbstract:
(Uploaded by Plazi for the Bat Literature Project) The interaction between climatic conditions and the ability of organisms to maintain homeostasis regulates the distribution of species on the planet. However, its influence on macroevolutionary dynamics is not well un derstood. It has been suggested that diversification rates will be different in lineages with narrow thermal niches (specialists) to diversification rates in generalist lineages, but the evidence for this is elusive. Here, we tested this hypothesis by using the most diverse (in species richness and geographic range variation) tropical bat genus within the Phyllostomidae family. We estimated the realized thermal niche breadth of Sturnira species from their geographic range and categorized them as generalists, cold specialists, or warm specialists. We compared dy namic evolutionary models that differ in 1) niche breadth evolution, 2) parental niche breadth inheritance, and 3) whether niche breadth evolution is associated with shifts in diversification rates. Our best-performing model indicates that most Sturnira species arose as specialists in warm climates and that over time, their niche breadth broadens, and just a subset of those species becomes specialists in cold environments. We found that the evo lution of realized thermal niche breadth causes fluctuations in per-lineage rates of diversification, where warm specialists boast the highest speciation rates. However, we found no evidence of these changes in niche neither triggering nor being a result of speciation events themselves; this suggests that diversification events in Sturnira could instead depend on allopatric speciation processes such as the development of geographic barriers.
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Carballo-Morales, Jorge D., Romeo A. Saldaña-Vázquez, Federico Villalobos, and Leonel Herrera-Alsina. "Thermal niche breadth and their relationship with sturnira bat species diversification." Journal of Thermal Biology 117 (July 10, 2023): 103697. https://doi.org/10.5281/zenodo.13477046.
Full textAbstract:
(Uploaded by Plazi for the Bat Literature Project) The interaction between climatic conditions and the ability of organisms to maintain homeostasis regulates the distribution of species on the planet. However, its influence on macroevolutionary dynamics is not well un derstood. It has been suggested that diversification rates will be different in lineages with narrow thermal niches (specialists) to diversification rates in generalist lineages, but the evidence for this is elusive. Here, we tested this hypothesis by using the most diverse (in species richness and geographic range variation) tropical bat genus within the Phyllostomidae family. We estimated the realized thermal niche breadth of Sturnira species from their geographic range and categorized them as generalists, cold specialists, or warm specialists. We compared dy namic evolutionary models that differ in 1) niche breadth evolution, 2) parental niche breadth inheritance, and 3) whether niche breadth evolution is associated with shifts in diversification rates. Our best-performing model indicates that most Sturnira species arose as specialists in warm climates and that over time, their niche breadth broadens, and just a subset of those species becomes specialists in cold environments. We found that the evo lution of realized thermal niche breadth causes fluctuations in per-lineage rates of diversification, where warm specialists boast the highest speciation rates. However, we found no evidence of these changes in niche neither triggering nor being a result of speciation events themselves; this suggests that diversification events in Sturnira could instead depend on allopatric speciation processes such as the development of geographic barriers.
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Carballo-Morales, Jorge D., Romeo A. Saldaña-Vázquez, Federico Villalobos, and Leonel Herrera-Alsina. "Thermal niche breadth and their relationship with sturnira bat species diversification." Journal of Thermal Biology 117 (July 17, 2023): 103697. https://doi.org/10.5281/zenodo.13477046.
Full textAbstract:
(Uploaded by Plazi for the Bat Literature Project) The interaction between climatic conditions and the ability of organisms to maintain homeostasis regulates the distribution of species on the planet. However, its influence on macroevolutionary dynamics is not well un derstood. It has been suggested that diversification rates will be different in lineages with narrow thermal niches (specialists) to diversification rates in generalist lineages, but the evidence for this is elusive. Here, we tested this hypothesis by using the most diverse (in species richness and geographic range variation) tropical bat genus within the Phyllostomidae family. We estimated the realized thermal niche breadth of Sturnira species from their geographic range and categorized them as generalists, cold specialists, or warm specialists. We compared dy namic evolutionary models that differ in 1) niche breadth evolution, 2) parental niche breadth inheritance, and 3) whether niche breadth evolution is associated with shifts in diversification rates. Our best-performing model indicates that most Sturnira species arose as specialists in warm climates and that over time, their niche breadth broadens, and just a subset of those species becomes specialists in cold environments. We found that the evo lution of realized thermal niche breadth causes fluctuations in per-lineage rates of diversification, where warm specialists boast the highest speciation rates. However, we found no evidence of these changes in niche neither triggering nor being a result of speciation events themselves; this suggests that diversification events in Sturnira could instead depend on allopatric speciation processes such as the development of geographic barriers.
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Dorn, David C. "Stem cell autotomy and niche interaction in different systems." World Journal of Stem Cells 7, no. 6 (2015): 922. http://dx.doi.org/10.4252/wjsc.v7.i6.922.
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Yu, Qianqian, Hongyu Li, Bing Zhang, Yun Song, Yueying Sun, and Zhaojun Ding. "ATP Hydrolases Superfamily Protein 1 (ASP1) Maintains Root Stem Cell Niche Identity through Regulating Reactive Oxygen Species Signaling in Arabidopsis." Plants 13, no. 11 (2024): 1469. http://dx.doi.org/10.3390/plants13111469.
Full textAbstract:
The maintenance of the root stem cell niche identity in Arabidopsis relies on the delicate balance of reactive oxygen species (ROS) levels in root tips; however, the intricate molecular mechanisms governing ROS homeostasis within the root stem cell niche remain unclear. In this study, we unveil the role of ATP hydrolase superfamily protein 1 (ASP1) in orchestrating root stem cell niche maintenance through its interaction with the redox regulator cystathionine β-synthase domain-containing protein 3 (CBSX3). ASP1 is exclusively expressed in the quiescent center (QC) cells and governs the integrity of the root stem cell niche. Loss of ASP1 function leads to enhanced QC cell division and distal stem cell differentiation, attributable to reduced ROS levels and diminished expression of SCARECROW and SHORT ROOT in root tips. Our findings illuminate the pivotal role of ASP1 in regulating ROS signaling to maintain root stem cell niche homeostasis, achieved through direct interaction with CBSX3.
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Zhang, Qing, Ruwang Jiao, Sanyou Zeng, and Zhigao Zeng. "Balancing Exploration and Exploitation With Decomposition-Based Dynamic Multi-Objective Evolutionary Algorithm." International Journal of Cognitive Informatics and Natural Intelligence 15, no. 4 (2021): 1–23. http://dx.doi.org/10.4018/ijcini.20211001.oa25.
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Balancing exploration and exploitation is a crucial issue in evolutionary global optimization. This paper proposes a decomposition-based dynamic multi-objective evolutionary algorithm for addressing global optimization problems. In the proposed method, the niche count function is regarded as a helper objective to maintain the population diversity, which converts a global optimization problem to a multi-objective optimization problem (MOP). The niche-count value is controlled by the niche radius. In the early stage of evolution, a large niche radius promotes the population diversity for better exploration; in the later stage of evolution, a niche radius close to 0 focuses on convergence for better exploitation. Through the whole evolution process, the niche radius is dynamically decreased from a large value to zero, which can provide a sound balance between the exploration and exploitation. Experimental results on CEC 2014 benchmark problems reveal that the proposed algorithm is capable of offering high-quality solutions, in comparison with four state-of-the-art algorithms.
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Sentosa, Agus Arifin, Astri Suryandari, and Amula Nurfiarini. "TROPHIC INTERACTIONS OF THE FISH COMMUNITIES IN CIRATA RESERVOIR, WEST JAVA." Indonesian Fisheries Research Journal 27, no. 2 (2021): 79. http://dx.doi.org/10.15578/ifrj.27.2.2021.79-90.
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The utilization of food resources by the fish communities in the Cirata Reservoir depends on the environmental conditions of the reservoir. Eutrophication and the presence of potentially invasive alien fishes could affect the trophic interactions of food utilization by the fish communities in the Cirata reservoir. This study aimed to analyze the trophic interactions of the fish communities in the Cirata Reservoir, West Java. The samplings were conducted in October, December 2018, and April 2019. The fish samples were collected using experimental gill nets with different mesh sizes. The stomach contents were dissected to study their food habits under a stereoscopic microscope. Data analysis was performed using the index of preponderance, niche breadth, trophic level, and index Schoener. A total of 21 species of fishes in the Cirata Reservoir utilized food resources, including phytoplankton, zooplankton, aquatic plants/macrophytes, molluscs, insects (adult and larvae), worms, a body part of fishes and crustaceans, pellets and detritus. The fish communities had a wide range of niche between 0.00-0.32 and trophic levels between 2.00-3.63. The non-native fishes in the Cirata Reservoir had the food overlapping potential with native fishes, from low to high categories, especially from the Cichlidae. Trophic interaction of fish communities in the Cirata reservoir was still relatively stable, characterized by overlapping food niche in the low to medium categories. The fish stock enhancement effort such as fish introduction or restocking in the Cirata Reservoir could still be carried out with a precautionary approach to filling empty niches and avoiding the potential for invasive alien fish species.
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Korneva, Yulia S., and Roman V. Ukrainets. "Principles of premetastatic niche formation." Journal of Modern Oncology 21, no. 4 (2020): 6–9. http://dx.doi.org/10.26442/18151434.2019.4.190715.
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The article is devoted to premetastatic niche as a complex term, including stromal cells, vessels, extracellular matrix and their changes during interaction with the primary tumor. On example of different malignant tumors authors describe as primary tumor through tumor exosomes prepares certain organs-recipients to metastatic clone implantation. In the area of premetastatic niche under the influence of tumorous exosomes polarization of macrophages towards M2 type takes place. The cells are the main agents, providing survival as well as migration of tumorous cells. Affecting extracellular matrix, macrophages change the microcirculatory bed permeability. This mechanism is directed towards increase of its permeability to entrance of metastatic clone cells form vessels into premetastatic niche. Besides macrophages fibroblasts and polypotent bone marrow stem cells are also reprogrammed, that results in metabolism and local immunity changes at the place of future implantation. As a result, only when tissue of recipient-organ is prepared for contact with metastatic clone, their interaction take place with consequent formation of secondary tumor metastatic niche. Thus, this review describes pathogenesis of metastasis, different from its early understanding as spread of metastatic clone with lymph and blood.
 These peculiarities may in future have significant impact in practical medicine, Blockage of signal spread from primary tumor through exosomes is one of the promising directions in pathogenetic therapy of malignant tumors. Investigation of principles of premetastatic niche formation may become a theoretical substantiation for prophylaxis of metastatic disease and inhibition of micrometastasis to macrometastasis transformation.
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Petrova, Tatiana V., Irina N. Nifontova, Daria A. Svinareva, Maria A. Vinogradova, Elena A. Michaylova, and Nina J. Drize. "Improvement of Hematopoietic and Stromal Cells Interaction after PTH Treatment of Long-Term Bone Marrow Cultures from Patients with Aplastic Anemia." Blood 108, no. 11 (2006): 1401. http://dx.doi.org/10.1182/blood.v108.11.1401.1401.
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Abstract Alterations in hematopoietic and stromal cells interactions could be one of the causes of aplastic anemia (AA). Assuming the existence of two types of stromal niches where hematopoietic stem cells (HSC) reside, - osteoblastic niche that regulates survival, self-maintenance abilities, adhesion, homing and quiescence, and vascular niche controlling proliferation and differentiation, - one could suggest an impairment of regulation in both of them in AA patients. As parathyroid hormone (PTH) activates osteoblasts it could potentially improve the survival of HSC in patients with various hematopoietic disorders. The aim of this study was to compare several functional characteristics of stromal cells from healthy donors and AA patients. In order to study stromal microenvironment capable to maintain hematopoiesis, long-term bone marrow cultures were established from 19 patients with AA and 24 healthy donors as a control group. PTH was added for 3 and 6 weeks of cultivation in concentration 10−8, 5x10−8 and 10−7 M once a week while changing half of the media. The proportion of CAFC 7 and CAFC 28–35 from the donor bone marrow survived cocultivation for 2–5 days with irradiated adherent cell layers (ACLs) of AA patients was estimated by limiting dilution assay. To characterize alterations in the expression of several genes in ACLs semi-quantitative analysis of RT-PCR products was performed using PhosphoImager Cyclone, Packard Bell (USA), after Southern blot hybridization with appropriate sequences. The level of b-actin expression was used as a normalization factor. All data from the patients was compared with corresponding gene’s expression level in donors ACLs. Among studied signaling molecules involved in niche regulation Ang-1 expression was significantly decreased (2.3-fold) in ACLs of patients after 3 weeks in culture. Further cultivation led to normalization of Ang-1 expression. Another difference in osteoblastic niche regulating genes was revealed in Notch 1 signaling. While in ACLs from donor bone marrow it increased 2-fold during cultivation, it was stable in ACLs from the patients. Expression level of ICAM-1 responsible for adhesion of HSC to osteoblasts in niche also increased (4-fold) during cultivation in ACLs from donors and did not change in AA patients. Expression level of all other studied genes of osteoblastic niche signaling pathways was not altered in ACLs of AA patients. Analysis of genes regulating stromal cells in vascular niche revealed increased level of VEGF (2-fold) accompanied with 2-fold decreased expression of VCAM-1 in ACLs of the patients. Expression level of both genes normalized with further cultivation. The data suggest the functional inhibition of stromal microenvironment in patients with aplastic anemia that could be overcomed by cultivation ex vivo. PTH treatment activating gene expression in ACLs of donors did not affect universally the same genes in patients. Nevertheless treatment with PTH improved survival (2–3-fold) of long-term repopulating HSC (CAFC 28–35) from donors bone marrow explanted on irradiated ACLs of AA patients. The survival rate of short-repopulating HSC (CAFC 7) was not sensitive to PTH treatment. So, in patients with aplastic anemia the impairment of stromal regulation of HSC was observed both in osteoblastic and vascular niches. PTH being the osteoblasts activator could partially improve functioning of stromal microenvironment and hence the HSC survival.
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Robertson-Tessi, Mark, Bina Desai, Tatiana Miti, et al. "Abstract B008: Therapy-protective peristromal niches mediate positive ecological interaction between therapy-sensitive and therapy-resistant cells, altering the evolutionary dynamics of acquired targeted therapy resistance in lung cancers." Cancer Research 84, no. 22_Supplement (2024): B008. http://dx.doi.org/10.1158/1538-7445.tumbody-b008.
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Abstract Pharmacological inhibitors of oncogenic signaling, such as drugs that target ALK kinase (ALKi) in ALK+ lung cancers, can induce strong and durable clinical responses. However, targeted therapies are not curative in advanced cancers and even strong responders eventually develop resistance. While therapy resistance is typically attributed to cell-intrinsic (epi)mutational characteristics of tumor cells, it can also result from interactions of tumor cells with the tumor microenvironment (TME). In contrast to the detailed elucidation of the molecular mediators of therapy resistance, our knowledge of the evolutionary dynamics underlying the resistance emergence, including the impact of TME, remains poorly defined. A key open question in understanding the evolutionary dynamics of therapy resistance is whether relapse results from an expansion of pre-existing therapy-resistant subpopulations or from a bona fide gradual evolutionary process. To elucidate this question, we integrated experimental mouse studies with mathematical modeling, interrogating therapeutic responses of therapy-naïve experimental xenograft ALK+ tumors, spiked-in with differentially labeled resistant cells. We found that ALKi treatment induced a rapid expansion of resistant cells, which drastically reduced the magnitude and duration of remissions. Surprisingly, our in silico analyses pointed to the existence of a strong positive ecological interaction between therapy-resistant and therapy-sensitive competitors. Using a combination of spatial analyses, experimental studies, and mathematical modeling, we found that this interaction was mediated by peristromal niches that protected therapy-sensitive tumor cells. Specifically, by limiting tumor regression, the therapy- induced expansion of resistant cells limited the loss of protective peristromal niches, while the subsequent resumption of tumor growth created new peristromal niches capable of supporting the survival and proliferation of therapy-sensitive cells. While this niche-mediated interaction had only a marginal impact on the transition from remission to relapse, enhanced survival of therapy-sensitive cells potentiated their ability to adapt to ALKi, leading to a higher diversity of resistance phenotypes. In summary, our study has revealed a new type of indirect, niche-mediated ecological interaction between therapy-resistant and therapy-sensitive cells. The rapid expansion of rare pre-existent resistant cells and fast transition to relapse challenge a common assumption of the pre-existence of therapy resistance. Finally, our results highlight the essentiality of TME considerations in understanding the evolutionary dynamic underlying the development of therapy resistance. Citation Format: Mark Robertson-Tessi, Bina Desai, Tatiana Miti, Pragya Kumar, Sagnik Yarlagadda, Rishi Shah, Robert Vander Velde, Daria Miroshnychenko, David Basanta, Alexander Anderson, Andriy Marusyk. Therapy-protective peristromal niches mediate positive ecological interaction between therapy-sensitive and therapy-resistant cells, altering the evolutionary dynamics of acquired targeted therapy resistance in lung cancers [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor-body Interactions: The Roles of Micro- and Macroenvironment in Cancer; 2024 Nov 17-20; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(22_Suppl):Abstract nr B008.
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Medyouf, Hind. "The microenvironment in human myeloid malignancies: emerging concepts and therapeutic implications." Blood 129, no. 12 (2017): 1617–26. http://dx.doi.org/10.1182/blood-2016-11-696070.
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Abstract Similar to their healthy counterpart, malignant hematopoietic stem cells in myeloid malignancies, such as myeloproliferative neoplasms, myelodysplastic syndromes, and acute myeloid leukemia, reside in a highly complex and dynamic cellular microenvironment in the bone marrow. This environment provides key regulatory signals for and tightly controls cardinal features of hematopoietic stem cells (HSCs), including self-renewal, quiescence, differentiation, and migration. These features are essential to maintaining cellular homeostasis and blood regeneration throughout life. A large number of studies have extensively addressed the composition of the bone marrow niche in mouse models, as well as the cellular and molecular communication modalities at play under both normal and pathogenic situations. Although instrumental to interrogating the complex composition of the HSC niche and dissecting the niche remodeling processes that appear to actively contribute to leukemogenesis, these models may not fully recapitulate the human system due to immunophenotypic, architectural, and functional inter-species variability. This review summarizes several aspects related to the human hematopoietic niche: (1) its anatomical structure, composition, and function in normal hematopoiesis; (2) its alteration and functional relevance in the context of chronic and acute myeloid malignancies; (3) age-related niche changes and their suspected impact on hematopoiesis; (4) ongoing efforts to develop new models to study niche-leukemic cell interaction in human myeloid malignancies; and finally, (5) how the knowledge gained into leukemic stem cell (LSC) niche dependencies might be exploited to devise novel therapeutic strategies that aim at disrupting essential niche-LSC interactions or improve the regenerative ability of the disease-associated hematopoietic niche.
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Thomas, Zachary, Bowen Wang, and Rong Lu. "Heterogeneous Intercellular Communication of Hematopoietic Stem Cells in the Mouse Bone Marrow." Blood 142, Supplement 1 (2023): 5617. http://dx.doi.org/10.1182/blood-2023-188073.
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Introduction.Hematopoietic stem cells (HSCs) are responsible for maintaining the homeostasis of the blood and immune systems. This process must rapidly adapt to bleeding, infection, injury, and disease. HSCs reside in specialized microenvironments in the bone marrow, called “niche”. Several bone marrow cell types have been proposed as the key components of the niche. It is well established that HSCs rely on molecular signals from the niche cells to survive, migrate, proliferate, and differentiate. Recent studies suggest that HSCs differentiate heterogeneously. Additionally, the bone marrow is a heterogeneous environment consisting of more than thirty cell types. This study will test the hypothesis that individual HSCs are engaged in heterogeneous intercellular signaling in the bone marrow. Materials and Methods.We utilized CellChat (Jin et al., 2021), a database for ligand-receptor pairs and associated pathways, to predict cell-cell signaling at the single cell level. We used single cell RNA sequencing data from mouse hematopoietic stem and progenitor cells, blood and immune cells, and non-hematopoietic cells from the bone marrow to determine putative cell-cell interactions. The predicted signaling interactions were then adjusted based on the cell-cell spatial interaction revealed by PhenoCycler measurement (Akoya Biosciences). Mouse bone marrow transplantation experiments were performed to test the functional significance of the identified signaling pathway interactions. Results.We found that individual HSCs send and receive different levels of molecular signals across various signaling pathways. In addition to the expected interactions with the known HSC niche cells, we also found new interactions between HSCs and their progeny cells including myeloid progenitors and immune cells. These cell-cell signaling interactions are consistent with the spatial interaction frequencies of the corresponding cell types as revealed by our imaging data from the PhenoCycler analysis. Further, we found that some signaling pathways are positively or negatively correlated across individual HSCs, indicating complex intercellular signaling networks. The most significant negative correlation was found between HSCs sending MHC-I signals and sending PARs signals (Figure). Moreover, this MHC-I/PARs signaling correlation network also involves signaling from the HSC niche, including those that are known to play roles in HSC homing such as ESAM and VCAM. Therefore, we tested the engraftment efficiency of HSCs that receive PARs and those that do not using the HSC mouse transplantation model. We found that PAR1 + HSCs engraft much less efficiently. Finally, we present the HSC Interaction Data Explorer (HIDE), a database that comprehensively depicts the interactions between HSCs and other bone marrow cells including the involved signaling pathways, ligands and receptors of the pathways, and the pathway correlations. Conclusion.Our study uncovered novel interactions of HSCs with myeloid progenitor cells and immune cells, which were validated by spatial interaction data. These interactions indicate feedback signaling in regulating blood cell regeneration. Our findings further revealed signaling pathway correlation networks across individual HSCs, and we showed their functional significance using transplantation experiments. Finally, we present HIDE as a resource that informs the interactions between HSCs and various bone marrow cells, the relevant signaling pathways, and the pathway correlations. Figure Legend. HSC signaling correlation networks. Each node shows a signaling pathway and direction (e.g., HSCs sending MHC-I). The edges represent the spearman correlation score.
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Haas, Simon, Chiara Baccin, Jude Al-Sabah, Lars Velten, Steinmetz Lars, and Andreas Trumpp. "Combined Single-Cell and Spatial Transcriptomics to Deconvolute the Hematopoietic Stem Cell Niche." Blood 132, Supplement 1 (2018): 876. http://dx.doi.org/10.1182/blood-2018-99-118479.
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Abstract Coordinated interaction of many cell types is required to facilitate hematopoietic and mesenchymal stem cell maintenance and differentiation in the bone marrow. However, the molecular factors and cell types involved in this complex interplay remain poorly understood. Here we developed a combined single cell and spatial transcriptomics approach to address this problem. Large-scale single-cell transcriptional profiling in conjunction with a multi-layered sorting approach allowed us to generate a complete and evenly sampled transcriptional map of all major bone and bone marrow populations. Our dataset covers all cell types or differentiation trajectories involved in mesenchymal and hematopoietic stem cell differentiation, osteogenesis, adipogenesis, myelopoiesis, erythropoiesis, lymphopoiesis, memory T cell formation as well as bone marrow neural innervation and vascularization at the single cell level. Using this data, we derive fundamental properties of the described cell types, clarify the cellular source of signals affecting stem cell differentiation processes and provide a systems view on putative intercellular interactions. Systematic spatial transcriptomics, using laser-capture microdissection of selected bone marrow niches followed by transcriptional profiling and bioinformatic cellular deconvolution, allowed us to confirm predicted interactions and map the cellular composition of distinct bone marrow niches. Our analyses highlight the importance of pre-adipogenic CXCL12 abundant reticular cells as key niche cells for stem cell maintenance, provides a holistic systems view of the hematopoietic stem cell niche and offers a novel approach to systematically deconvolute the molecular, cellular and spatial composition of complex tissues. Disclosures No relevant conflicts of interest to declare.
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Rhodes, Katherine A., Man Cheong Ma, María A. Rendón, and Magdalene So. "Neisseria genes required for persistence identified via in vivo screening of a transposon mutant library." PLOS Pathogens 18, no. 5 (2022): e1010497. http://dx.doi.org/10.1371/journal.ppat.1010497.
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The mechanisms used by human adapted commensal Neisseria to shape and maintain a niche in their host are poorly defined. These organisms are common members of the mucosal microbiota and share many putative host interaction factors with Neisseria meningitidis and Neisseria gonorrhoeae. Evaluating the role of these shared factors during host carriage may provide insight into bacterial mechanisms driving both commensalism and asymptomatic infection across the genus. We identified host interaction factors required for niche development and maintenance through in vivo screening of a transposon mutant library of Neisseria musculi, a commensal of wild-caught mice which persistently and asymptomatically colonizes the oral cavity and gut of CAST/EiJ and A/J mice. Approximately 500 candidate genes involved in long-term host interaction were identified. These included homologs of putative N. meningitidis and N. gonorrhoeae virulence factors which have been shown to modulate host interactions in vitro. Importantly, many candidate genes have no assigned function, illustrating how much remains to be learned about Neisseria persistence. Many genes of unknown function are conserved in human adapted Neisseria species; they are likely to provide a gateway for understanding the mechanisms allowing pathogenic and commensal Neisseria to establish and maintain a niche in their natural hosts. Validation of a subset of candidate genes confirmed a role for a polysaccharide capsule in N. musculi persistence but not colonization. Our findings highlight the potential utility of the Neisseria musculi-mouse model as a tool for studying the pathogenic Neisseria; our work represents a first step towards the identification of novel host interaction factors conserved across the genus.
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Chen, Shuying, Qing Rao, Haiyan Xing, et al. "Rac1 Gtpase Promotes Hematopoietic Stem Cell Migration, Self-Renewal and Participates in Leukemia Initiation and Maintenance." Blood 124, no. 21 (2014): 2923. http://dx.doi.org/10.1182/blood.v124.21.2923.2923.
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Abstract Acute myeloid leukemia (AML) is a hematological malignancy resulting from the transformation of normal hematopoietic stem cell (HSC). Except for the intrinsic factors, it is acceptable that some extrinsic events from microenvironment could be the important co-factors in the development of leukemia. In addition to the specific component, as an extrinsic factor, interaction between HSC and bone marrow niche regulates HSCs fate. Disruption on the interactions also influences hematopoiesis. It has become evident that Rac members of Rho GTPases family are important molecules regulating HSCs interactions with hematopoietic microenvironment and activation of Rac1 are observed in a serials of leukemia cells. We previously reported that Rac1 is highly expressed in leukemia cells and found that activation of Rac1 GTPase lead to an increase in leukemia cells migration, chemotherapy resistance, quiescence and trafficking to bone marrow niche. Furthermore, we showed that Rac1 mediated the localization in niche is further attributable to the maintenance of LSC quiescence. In this study, we investigated the effects of active Rac1 GTPase in the transformation of HSC and determined if the activation of Rac1GTPase could promote the interaction of HSC with osteoblastic niche and further contribute to the leukomogenesis. By forced expression of a constitutively active form of Rac1 GTPase (Rac1 V12）in c-Kit+ hematopoietic stem/progenitor cell, we show that activation of Rac1 GTPase promotes cell migration, adhesion and colony formation, and also lead to an increase in the frequency of cells in quiescent state. Gene expression analysis shows that activation of Rac1 up-regulates the expression of several molecules that mediated the interaction of LSC with osteoblastic niche, as well as the cell cycle inhibitors such as p21, p27, and p57. Furthermore, we established a mouse model of acute myeloid leukemia by transduction murine c-kit+HSPC with Rac1 V12 combined with AML1-ETO9a, followed by transplantation into lethally irradiated mice. To investigate the role of Rac1 activation in leukemogenesis in vivo, we treated the AML1-ETO-Rac1 leukemia cells with Rac1 GTPase inhibitor EHT1846 and then transplanted into recipient mice. After 40 μM EHT1846 treatment, no engraftment of AML cells in recipient mice was observed. Kaplan-Meier analyses indicate that treatment with EHT1846 significantly prolongs survival of the transplanted mice. 20μM dose of EHT1846 was less effective. These data indicated that active Rac1 might be an important contributing factor to leukemogenesis. In addition, short-term homing assays showed that EHT 1846 treatment causes a marked inhibition of AML cell homing into both bone marrow and spleen as compared with controls, indicating that Rac1 mediated homing could be an important step and participated in the leukemogensis. Altogether, our data suggest that activation of Rac1 GTPase is critical for the interaction between HSCs with BM niche and even be contributed to leukemia development. Disclosures Wang: Novartis: Consultancy; Bristol Myers Squibb: Consultancy.
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Wells, K., M. B. Lakim, and J.-C. Beaucournu. "Host specificity and niche partitioning in flea-small mammal networks in Bornean rainforests." Medical and Veterinary Entomology 25, no. 3 (2011): 311–19. https://doi.org/10.5281/zenodo.13508425.
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(Uploaded by Plazi for the Bat Literature Project) The diversity of ectoparasites in Southeast Asia and flea–host associations remain largely understudied. We explore specialization and interaction patterns of fleas infesting non-volant small mammals in Bornean rainforests, using material from a field survey carried out in two montane localities in northwestern Borneo (Sabah, Malaysia) and from a literature database of all available interactions in both lowland and montane forests. A total of 234 flea individuals collected during our field survey resulted in an interaction network of eight flea species on seven live-captured small mammal species. The interaction network from all compiled studies currently includes 15 flea species and 16 small mammal species. Host specificity and niche partitioning of fleas infesting diurnal treeshrews and squirrels were low, with little difference in specialization among taxa, but host specificity in lowland forests was found to be higher than in montane forests. By contrast, Sigmactenus alticola (Siphonaptera: Leptopsyllidae) exhibited low host specificity by infesting various montane and lowland nocturnal rats. However, this species exhibited low niche partitioning as it was the only commonly recorded flea from rats on Borneo. Overall complementary specialization was of intermediate intensity for both networks and differed significantly from random association; this has important implications for specific interactions that are also relevant to the potential spread of vector-borne diseases.