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Journal articles on the topic 'Habitat fractionation'
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1
Cao, Dechang, Matthias Schöttner, Rayko Halitschke, et al. "Syringaldehyde is a novel smoke-derived germination cue for the native fire-chasing tobacco, Nicotiana attenuata." Seed Science Research 31, no. 4 (2021): 292–99. http://dx.doi.org/10.1017/s0960258521000271.
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AbstractSmoke-derived seed germination is an important trait for plants to colonize postfire habitats. The well-characterized smoke-derived chemicals of karrikins germinate seeds of species not known to occur after fires in nature. Hence, the ecologically relevant germination cues in smoke remain to be explored for native postfire plants. With the fire-chaser, Nicotiana attenuata, we revisit a bioassay-driven fractionation of liquid smoke to identify ecologically relevant germination cues. By combining bioassay-guided fractionation and comparative unbiased metabolomics, we developed a robust and efficient method to identify germination cues in smoke. Syringaldehyde (SAL) was re-identified as a germination cue in fractions of liquid smoke that promote seed germination. SAL was found to be produced during wildfires in the plant's native habitat, efficiently adsorbed to N. attenuata seeds from aqueous solutions and not readily leached from soil and accurately predicted the boundaries of natural fire events that reflect the occurrence of native postfire N. attenuata populations. We propose that SAL is an ecologically relevant germination cue in smoke for this species.
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Burbank, J., DAR Drake, and M. Power. "Field-based oxygen isotope fractionation for the conservation of imperilled fishes: an application with the threatened silver shiner Notropis photogenis." Endangered Species Research 42 (July 2, 2020): 83–93. http://dx.doi.org/10.3354/esr01040.
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Identifying the realized thermal habitat of animals is important for understanding life history and population processes, yet methods to estimate realized thermal use are lacking for many small-bodied organisms, including imperilled fishes. Analysis of oxygen isotopes provides one solution, but requires the development of species-specific fractionation equations. To date, such equations have generally been limited to commercial or game fish species. Here, we developed a field-based fractionation equation for the threatened silver shiner Notropis photogenis to better understand the thermal ecology of the species in an urban watershed. Archived otoliths were analyzed for oxygen isotope values (δ18O). There was a significant linear relationship between otolith isotope fractionation and water temperature, described by δ18Ootolith(VPBD) - δ18Owater(VPBD) = 32.03 - 0.21(°C). Results indicate that otolith isotope techniques can be used to identify the average relative temperature occupied by silver shiner, representing the first investigation of oxygen isotopes to understand thermal occupancy of the species. This field-based equation provides an opportunity to understand how silver shiner may respond to alterations in stream temperatures resulting from urbanization and climate effects and may be useful in identifying thermal refugia for the species. Field-based, species-specific fractionation equations can provide insights into the thermal ecology of many small-bodied fishes, which are increasingly imperilled due to thermal stressors.
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Ding, Fangjun, Congjun Yuan, Ting Zhou, Juan Cheng, Peng Wu, and Yuyan Ye. "Water-Use Strategies and Habitat Adaptation of Four Tree Species in Karstic Climax Forest in Maolan." Water 15, no. 1 (2023): 203. http://dx.doi.org/10.3390/w15010203.
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The technique of stable hydrogen and oxygen isotope tracing has become an important means to study the mechanism of water movement due to its high sensitivity and traceability. In this study, four dominant tree species in the karst forest of Maolan, Guizhou Province, were selected, and their water-use strategies and the mechanism of maintenance of tree species diversity were investigated using the stable hydrogen and oxygen isotope tracing technique. The results show that: (1) The regional precipitation varied evidently with the alternation of seasons, i.e., the values of δD and δ18O in precipitation had a positive bias in spring and a negative bias in summer and autumn. The value of deuterium excess (d-excess) was between 11.67‰ and 31.02‰, with a mean value of 22.98‰. (2) The soil temperature (ST), soil water content (SWC) and precipitation, which have a significant positive correlation, imposed a joint impact on the dynamics of the soil evaporative fractionation. (3) The line-conditioned excess (LC-excess) varied seasonally in different water bodies, i.e., the relative evaporative fractionation of the rhizosphere soil of deciduous tree species was stronger than that of evergreen tree species, and the evaporative fractionation of hydrogen and oxygen isotopes in the leaf water of evergreen tree species was stronger than that of deciduous tree species in spring and summer. However, that of the latter was stronger than that of the former in autumn. (4) The soil water was the most important potential water source for dominant tree species in karst terrain (71%), followed by epikarstic water, which made up an effective supplement (29%). (5) Finally, trees of different life forms and species varied in capacity and proportion in terms of using the potential water sources in different seasons, i.e., deciduous tree species had a greater capacity for using water from potential sources and variable water-use strategies. This may be a major water-limiting mechanism that maintains photosynthesis in the leaves of evergreen tree species (leaves are evergreen and plants continue to grow via photosynthesis) and constrains photosynthesis in deciduous tree species (leaves fall and plants become dormant and stop growing). These results lead to the conclusion that the dominant tree species in karstic forests resist water stress and adjust water-use strategies towards each potential water source to adapt to the harsh karstic habitat through root plasticity and leaf defoliation.
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Binstock, Addie L., Audrey S. Fox та John A. Mohan. "Isotopic Turnover and Fractionation of δ15N and δ13C in Captive Pseudopleuronectes americanus (Walbaum)". Fishes 8, № 9 (2023): 469. http://dx.doi.org/10.3390/fishes8090469.
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Stable isotope ratios of nitrogen (δ15N) and carbon (δ13C) are ubiquitous ecological tracers used to elucidate an organism’s diet and habitat. However, the application of stable isotope ratios to reconstruct a consumer’s ecology relies upon accurate rates for isotopic turnover at both a tissue and species-specific level. This study estimated isotope turnover rates and trophic discrimination factors in four different tissues (liver, digestive tissue, muscle, and skin) with variable metabolic activity in winter flounder Pseudopleuronectes americanus using a controlled diet-switch experiment. Differences in half-lives were noted among the tissues and between the experimental diets for both δ15N and δ13C. The experimental diets of krill and mysis had variability in nutritional composition, resulting in similar turnovers in δ15N but slower turnovers in δ13C for fish fed krill. Turnovers in both δ15N and δ13C were strongly influenced by metabolism, with the contribution reaching up to 98%, as fish exhibited minimal overall growth. The results of this study demonstrate the importance of considering differences in the catabolic activity of tissue maintenance for fish exhibiting minimal growth, as well as differences in metabolic assimilation of dietary sources that vary in their protein and lipid contents.
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De Wispelaere, Lien, Samuel Bodé, Pedro Hervé-Fernández, Andreas Hemp, Dirk Verschuren, and Pascal Boeckx. "Plant water resource partitioning and isotopic fractionation during transpiration in a seasonally dry tropical climate." Biogeosciences 14, no. 1 (2017): 73–88. http://dx.doi.org/10.5194/bg-14-73-2017.
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Abstract. Lake Chala (3°19′ S, 37°42′ E) is a steep-sided crater lake situated in equatorial East Africa, a tropical semiarid area with a bimodal rainfall pattern. Plants in this region are exposed to a prolonged dry season, and we investigated if (1) these plants show spatial variability and temporal shifts in their water source use; (2) seasonal differences in the isotopic composition of precipitation are reflected in xylem water; and (3) plant family, growth form, leaf phenology, habitat and season influence the xylem-to-leaf water deuterium enrichment. In this study, the δ2H and δ18O of precipitation, lake water, groundwater, plant xylem water and plant leaf water were measured across different plant species, seasons and plant habitats in the vicinity of Lake Chala. We found that plants rely mostly on water from the short rains falling from October to December (northeastern monsoon), as these recharge the soil after the long dry season. This plant-available, static water pool is only slightly replenished by the long rains falling from February to May (southeastern monsoon), in agreement with the two water worlds hypothesis, according to which plants rely on a static water pool while a mobile water pool recharges the groundwater. Spatial variability in water resource use exists in the study region, with plants at the lakeshore relying on a water source admixed with lake water. Leaf phenology does not affect water resource use. According to our results, plant species and their associated leaf phenology are the primary factors influencing the enrichment in deuterium from xylem water to leaf water (εl/x), with deciduous species giving the highest enrichment, while growth form and season have negligible effects. Our observations have important implications for the interpretation of δ2H of plant leaf wax n-alkanes (δ2Hwax) from paleohydrological records in tropical East Africa, given that the temporal variability in the isotopic composition of precipitation is not reflected in xylem water and that leaf water deuterium enrichment is a key factor in shaping δ2Hwax. The large interspecies variability in xylem–leaf enrichment (24 ± 28 ‰) is potentially troublesome, taking into account the likelihood of changes in species assemblage with climate shifts.
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Vanbeselaere, Jorick, Chunsheng Jin, Barbara Eckmair, Iain B. H. Wilson, and Katharina Paschinger. "Sulfated and sialylated N-glycans in the echinoderm Holothuria atra reflect its marine habitat and phylogeny." Journal of Biological Chemistry 295, no. 10 (2020): 3159–72. http://dx.doi.org/10.1074/jbc.ra119.011701.
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Among the earliest deuterostomes, the echinoderms are an evolutionary important group of ancient marine animals. Within this phylum, the holothuroids (sea cucumbers) are known to produce a wide range of glycoconjugate biopolymers with apparent benefits to health; therefore, they are of economic and culinary interest throughout the world. Other than their highly modified glycosaminoglycans (e.g. fucosylated chondroitin sulfate and fucoidan), nothing is known about their protein-linked glycosylation. Here we used multistep N-glycan fractionation to efficiently separate anionic and neutral N-glycans before analyzing the N-glycans of the black sea cucumber (Holothuria atra) by MS in combination with enzymatic and chemical treatments. These analyses showed the presence of various fucosylated, phosphorylated, sialylated, and multiply sulfated moieties as modifications of oligomannosidic, hybrid, and complex-type N-glycans. The high degree of sulfation and fucosylation parallels the modifications observed previously on holothuroid glycosaminoglycans. Compatible with its phylogenetic position, H. atra not only expresses vertebrate motifs such as sulfo– and sialyl–Lewis A epitopes but displays a high degree of anionic substitution of its glycans, as observed in other marine invertebrates. Thus, as for other echinoderms, the phylum- and order-specific aspects of this species' N-glycosylation reveal both invertebrate- and vertebrate-like features.
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Stillman, J. H., and G. N. Somero. "A comparative analysis of the evolutionary patterning and mechanistic bases of lactate dehydrogenase thermal stability in porcelain crabs, genus Petrolisthes." Journal of Experimental Biology 204, no. 4 (2001): 767–76. http://dx.doi.org/10.1242/jeb.204.4.767.
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The kinetic properties of orthologous homologs (orthologs) of enzymes are typically correlated with environmental temperatures in species adapted to different thermal regimes, but correlations between adaptation temperature and enzyme thermal stability are less clear. Although the thermal stability of a protein is related chiefly to its primary structure (including post-translational modification), thermal stability can also be altered by extrinsic factors present in the intracellular milieu. Here, we present a comparative analysis of the thermal stability of lactate dehydrogenase (LDH) orthologs from 22 congeneric species of porcelain crab (genera Petrolisthes and Allopetrolisthes) from a broad range of thermal habitats. Interspecific diversity of LDH stability is high: temperatures required for a 50 % loss of activity in 10 min ranged from 65 to 75.5 degrees C, corresponding to half-lives of less than 1 min to more than 3 h at 70 degrees C. Although stability is positively correlated with maximal habitat temperature in some sister taxa, phylogenetic comparative analysis incorporating all 22 species does not indicate that the interspecific diversity of LDH stability represents an adaptive response to current thermal habitats. Examination of the mechanistic bases of LDH stabilization indicates that differences in stability are related both to properties of the LDH molecule itself (intrinsic stability) and to the effects of extrinsic protein(s). Intrinsic differences were shown by the unfolding of structure during heating, as measured by circular dichroism spectroscopy. Stabilizing effects of extrinsic proteins are implied by the results of cellular fractionation experiments that removed low-molecular-mass solutes and proteins from the muscle homogenates. We conclude that the overall structural stability and functional properties of proteins can evolve independently and that in vivo protein-protein interactions can provide another means to regulate protein stability selectively.
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Ossa Ossa, Frantz, Marie-Laure Pons, Andrey Bekker, et al. "Zinc enrichment and isotopic fractionation in a marine habitat of the c. 2.1 Ga Francevillian Group: A signature of zinc utilization by eukaryotes?" Earth and Planetary Science Letters 611 (June 2023): 118147. http://dx.doi.org/10.1016/j.epsl.2023.118147.
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Munusamy, Madhaiyan, Kenneth Tan, Choy Eng Nge, et al. "Diversity and Biosynthetic Potential of Fungi Isolated from St. John’s Island, Singapore." International Journal of Molecular Sciences 24, no. 2 (2023): 1033. http://dx.doi.org/10.3390/ijms24021033.
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Adaptation to a wide variety of habitats allows fungi to develop unique abilities to produce diverse secondary metabolites with diverse bioactivities. In this study, 30 Ascomycetes fungi isolated from St. John’s Island, Singapore were investigated for their general biosynthetic potential and their ability to produce antimicrobial secondary metabolites (SMs). All the 30 fungal isolates belong to the Phylum Ascomycota and are distributed into 6 orders and 18 genera with Order Hypocreales having the highest number of representative (37%). Screening for polyketide synthase (PKS) and nonribosomal peptide synthetase (NRPS) genes using degenerate PCR led to the identification of 23 polyketide synthases (PKSs) and 5 nonribosomal peptide synthetases (NRPSs) grouped into nine distinct clades based on their reduction capabilities. Some of the identified PKSs genes share high similarities between species and known reference genes, suggesting the possibility of conserved biosynthesis of closely related compounds from different fungi. Fungal extracts were tested for their antimicrobial activity against S. aureus, Methicillin-resistant S. aureus (MRSA), and Candida albicans. Bioassay-guided fractionation of the active constituents from two promising isolates resulted in the isolation of seven compounds: Penilumamides A, D, and E from strain F4335 and xanthomegnin, viomellein, pretrichodermamide C and vioxanthin from strain F7180. Vioxanthin exhibited the best antibacterial activity with IC50 values of 3.0 μM and 1.6 μM against S. aureus and MRSA respectively. Viomellein revealed weak antiproliferative activity against A549 cells with an IC50 of 42 μM. The results from this study give valuable insights into the diversity and biosynthetic potential of fungi from this unique habitat and forms a background for an in-depth analysis of the biosynthetic capability of selected strains of interest with the aim of discovering novel fungal natural products.
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Detmers, Jan, Volker Brüchert, Kirsten S. Habicht, and Jan Kuever. "Diversity of Sulfur Isotope Fractionations by Sulfate-Reducing Prokaryotes." Applied and Environmental Microbiology 67, no. 2 (2001): 888–94. http://dx.doi.org/10.1128/aem.67.2.888-894.2001.
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ABSTRACT Batch culture experiments were performed with 32 different sulfate-reducing prokaryotes to explore the diversity in sulfur isotope fractionation during dissimilatory sulfate reduction by pure cultures. The selected strains reflect the phylogenetic and physiologic diversity of presently known sulfate reducers and cover a broad range of natural marine and freshwater habitats. Experimental conditions were designed to achieve optimum growth conditions with respect to electron donors, salinity, temperature, and pH. Under these optimized conditions, experimental fractionation factors ranged from 2.0 to 42.0‰. Salinity, incubation temperature, pH, and phylogeny had no systematic effect on the sulfur isotope fractionation. There was no correlation between isotope fractionation and sulfate reduction rate. The type of dissimilatory bisulfite reductase also had no effect on fractionation. Sulfate reducers that oxidized the carbon source completely to CO2 showed greater fractionations than sulfate reducers that released acetate as the final product of carbon oxidation. Different metabolic pathways and variable regulation of sulfate transport across the cell membrane all potentially affect isotope fractionation. Previous models that explained fractionation only in terms of sulfate reduction rates appear to be oversimplified. The species-specific physiology of each sulfate reducer thus needs to be taken into account to understand the regulation of sulfur isotope fractionation during dissimilatory sulfate reduction.
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Hill, T. M., C. R. Myrvold, H. J. Spero, and T. P. Guilderson. "Evidence for benthic–pelagic food web coupling and carbon export from California margin bamboo coral archives." Biogeosciences 11, no. 14 (2014): 3845–54. http://dx.doi.org/10.5194/bg-11-3845-2014.
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Abstract. Deep-sea bamboo corals (order Gorgonacea, family Isididae) are known to record changes in water mass chemistry over decades to centuries. These corals are composed of a two-part skeleton of calcite internodes segmented by gorgonin organic nodes. We examine the spatial variability of bamboo coral organic node 13C/12C and 15N/14N from 13 bamboo coral specimens sampled along the California margin (37–32° N, 792–2136 m depth). Radiocarbon analyses of the organic nodes show the presence of the anthropogenic bomb spike, indicating the corals utilize a surface-derived food source (pre-bomb D14C values of ∼−100‰, post-bomb values up to 82‰). Carbon and nitrogen isotope data from the organic nodes (δ13C = −15.9‰ to −19.2‰; δ15N = 13.8‰ to 19.4‰) suggest selective feeding on surface-derived organic matter or zooplankton. A strong relationship between coral δ15N and habitat depth indicates a potential archive of changing carbon export, with decreased δ15N values reflecting reduced microbial degradation (increased carbon flux) at shallower depths. Using four multi-centennial-length coral records, we interpret long-term δ15N stability in the California Current. Organic node δ15C values record differences in carbon isotope fractionation dictated by nearshore vs. offshore primary production. These findings imply strong coupling between primary production, pelagic food webs, and deep-sea benthic communities.
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Hoekstra, P. F., L. A. Dehn, J. C. George, K. R. Solomon, D. CG Muir, and T. M. O'Hara. "Trophic ecology of bowhead whales (Balaena mysticetus) compared with that of other arctic marine biota as interpreted from carbon-, nitrogen-, and sulfur-isotope signatures." Canadian Journal of Zoology 80, no. 2 (2002): 223–31. http://dx.doi.org/10.1139/z01-229.
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In this study, stable carbon (δ13C), nitrogen (δ15N), and sulfur (δ34S) isotope ratios were measured in muscle tissue from the BeringChukchiBeaufort Sea population of bowhead whales (Balaena mysticetus; n = 84) and various marine biota between 1997 and 2000. In previous investigations, stable carbon and nitrogen isotope ratios in baleen from this population have been used to elucidate age, migratory behaviour, and feeding ecology. However, information on δ13C, δ15N, and δ34S isotope patterns in bowhead whale muscle tissue and variability within the Bering Sea population is limited. Stable sulfur isotope values did not vary with δ13C enrichment for three consecutive seasons (n = 53) and this suggests that habitat selection by bowhead whales was consistent over the sampling period. We found that in contrast to other studies, seasonal differences (spring versus fall) in δ13C values were not associated with seasonal changes in δ15N values, suggesting either that bowhead whales maintain a consistently lower trophic position relative to other marine mammals or that stable carbon and nitrogen isotope fractionation is tissue-dependent and (or) isotope-dependent within this species. Seasonal fluctuation in δ13C values was consistent for all age classes of bowhead whales and suggests that the Bering and Beaufort seas are both important regions for feeding.
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Hill, T. M., C. R. Myrvold, H. J. Spero, and T. P. Guilderson. "Evidence for benthic-pelagic food web coupling and carbon export from California margin bamboo coral archives." Biogeosciences Discussions 11, no. 2 (2014): 2595–621. http://dx.doi.org/10.5194/bgd-11-2595-2014.
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Abstract. Deep-sea bamboo corals (order Gorgonacea, family Isididae) are known to record changes in water mass chemistry over decades to centuries. These corals are composed of a two-part skeleton of calcite internodes segmented by gorgonin organic nodes. We examine the spatial variability of bamboo coral organic node 13C/12C and 15N/14N from thirteen bamboo coral specimens sampled along the California margin (37–32° N; 792 to 2136 m depth). Radiocarbon analyses of the organic nodes show the presence of the anthropogenic bomb spike, indicating the corals utilize a surface-derived food source (pre-bomb D14C values of ∼ −100‰, post-bomb values to 82‰). Carbon and nitrogen isotope data from the organic nodes (13C = −15.9‰ to −19.2‰ 15N = 13.8‰ to 19.4‰) suggest selective feeding on surface-derived organic matter or zooplankton. A strong relationship between coral 15N and habitat depth indicate a potential archive of changing carbon export, with decreased 15N values reflecting reduced microbial degradation (increased carbon flux) at shallower depths. Using four multi-centennial length coral records, we interpret long-term 15N stability in the California Current. Organic node 13C values record differences in carbon isotope fractionation dictated by nearshore vs. offshore primary production. These findings imply strong coupling between primary production, pelagic food webs, and deep-sea benthic communities.
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Landman, Neil H., J. Kirk Cochran, Danny M. Rye, Kazushige Tanabe, and John M. Arnold. "Early life history of Nautilus: evidence from isotopic analyses of aquarium-reared specimens." Paleobiology 20, no. 1 (1994): 40–51. http://dx.doi.org/10.1017/s009483730001112x.
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Specimens of Nautilus species caught in the wild show a marked increase in oxygen isotopic composition between embryonic and postembryonic septa. The significance of this increase in terms of the early life history of Nautilus has been unclear. To help explain this pattern, we analyzed the isotopic composition of the septa of three specimens of Nautilus belauensis raised in aquariums under controlled temperature conditions. Our results indicate that both embryonic and postembryonic septa are secreted with the same temperature-dependent fractionation of aragonite relative to water as that of other aragonite-secreting molluscs (Grossman and Ku 1986). The δ18O values of the septa thus provide a reliable means of determining the water temperature in which the septa form. Calculated temperatures based on oxygen isotopic data from specimens caught in the wild reveal that embryonic development occurs at 22°-24° corresponding to a depth of 100-200 m depending on the location. The increase in δ18O in postembryonic septa reflects a migration into colder, deeper water after hatching. In Cretaceous nautilids, a systematic shift in δ18O is not present, indicating that these animals probably did not change their habitat after hatching. This is consistent with the likelihood that they lived in shallower environments than that of modern Nautilus.
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Fan, Tao, Jie Li, Ya Li, and Xiu Qin Zhu. "Stable Isotopic Study on Water Utilization Sources of Pinus yunnanensis Plantations in the Central Yunnan Karst Plateau." Advanced Materials Research 726-731 (August 2013): 3888–93. http://dx.doi.org/10.4028/www.scientific.net/amr.726-731.3888.
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In order to explain the water utilization mechanism of Pinus Yunnanensis plantations in the Central Yunnan Karst Plateau, SW China, and their adaptive strategies to arid karst habitat, the authors collected and analyzed the stable 18O isotope values of stem water of Pinus Yunnanensis in Bajiang valley, and their accompanying trees and bushes and their potential water sources. The IsoSource model was applied to compute the probable contribution of multiple potential water sources to total plant. The results show that in the ecosystem of Pinus Yunnanensis plantations, there exists significant evaporative isotopic fractionation during the process of hydraulic infiltration from precipitation to ground water and soil water and that of hydraulic redistribution in the soil profile. Water utilization positions and proportions of Pinus Yunnanensis and its accompanying trees and bushes vary from season to season, and they are evident competitors for water. During dry seasons, mature Pinus Yunnanensis uses 68.6% of 0-55cm soil water while the contribution of 30-110cm soil water and groundwater to the young Pinus Yunnanensis reaches 55.8% and 31.7% respectively. In rainy seasons, the use ratio of 0-55cm surface soil water by young Pinus Yunnanensis, Pistacia weinmannifolia and Rhododendron spiciferum are 63.1%, 56.3% and 86.2% respectively while the mature Pinus Yunnanensis uses rainfall, groundwater and fog droplets of canopy interception.
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Shi, Zejin, Guan Yin, Wenjie Li, et al. "Major geological events in the late Guadalupian and carbon–strontium isotope responses in the Yangtze platform, South China." Canadian Journal of Earth Sciences 54, no. 10 (2017): 1025–32. http://dx.doi.org/10.1139/cjes-2017-0103.
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Two sections of marine carbonate strata, Podu and Lengshuixi, from the Yangtze platform, South China, are investigated in terms of major geological events and carbon–strontium isotope responses. The results show a large-scale regression and a Large Igneous Province (LIP) event occurred in succession in the short interval of the late Guadalupian, inducing a biodiversity crisis. The regression event, marked by an increase in the 87Sr/86Sr ratio, is observed in the Jinogondolella postserrata Zone. It contributed significantly to the reduction in species habitat, leading to notable losses within the shallow-water species assemblage. A subsequent LIP event occurred after the appearance of Jinogondolella altudaensis, releasing CO2 and numerous other deleterious gases that further amplified the crisis in shallow-water to deep-sea environments. The corresponding decline in Sr and C isotopes could have been a response to the basaltic eruption (relative increase from mantle-derived Sr) and release of 12C-enriched CO2. During the process of creation of the LIP, the decline in δ13Ccarb was mainly associated with 12C-enriched CO2 release from organic matter in sedimentary strata, and high-temperature isotope fractionation during the volcanic eruption stage (exceeding 1200 °C). This study could further provide valuable clues regarding the development process of the major geological events and the causes of the biodiversity crisis.
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Wanek, Wolfgang, Werner Huber, Stefan K. Arndt, and Marianne Popp. "Mode of photosynthesis during different life stages of hemiepiphytic Clusia species." Functional Plant Biology 29, no. 6 (2002): 725. http://dx.doi.org/10.1071/pp01206.
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This paper originates from a presentation at the IIIrd International Congress on Crassulacean Acid Metabolism, Cape Tribulation, Queensland, Australia, August 2001. Carbon isotope fractionation and nocturnal acid accumulation in Clusia osaensis Hammel-ined., C. �peninsulae Hammel-ined. and C. valerii Standl. were investigated during the seedling, epiphytic and hemiepiphytic phases in a lowland tropical forest in Costa Ricato study photosynthetic adaptations of different plant growth stages to their habitat. Foliar δ 13C values around -24 to -32‰ indicate predominant C3 fixation of CO2 and low crassulacean acid metabolism (CAM) activity in all three Clusia species. Only terrestrially rooted plants of C. osaensis showed increased CAM expression. However, all developmental stages exhibited significant CAM cycling as shown by significant day-night fluctuations of titratable protons and of malic and citric acid. In C. valerii and C. peninsulae, an increase in CAM expression with plant development was not observed, and CAM cycling in hemiepiphytic-stage plants was completely repressed during the high rainfall season. The expression of CAM in the three Clusia species is therefore not developmentally controlled but triggered by environmental factors such as water availability and light intensity. These factors remain relatively stable in this ecosystem and CAM is therefore not fully expressed. However, CAM cycling may be of ecophysiological significance in all life stages as it serves as a mechanism to improve carbon economy by reducing respiratory CO2 losses.
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Völpel, Rike, André Paul, Annegret Krandick, Stefan Mulitza, and Michael Schulz. "Stable water isotopes in the MITgcm." Geoscientific Model Development 10, no. 8 (2017): 3125–44. http://dx.doi.org/10.5194/gmd-10-3125-2017.
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Abstract. We present the first results of the implementation of stable water isotopes in the Massachusetts Institute of Technology general circulation model (MITgcm). The model is forced with the isotopic content of precipitation and water vapor from an atmospheric general circulation model (NCAR IsoCAM), while the fractionation during evaporation is treated explicitly in the MITgcm. Results of the equilibrium simulation under pre-industrial conditions are compared to observational data and measurements of plankton tow records (the oxygen isotopic composition of planktic foraminiferal calcite). The broad patterns and magnitude of the stable water isotopes in annual mean seawater are well captured in the model, both at the sea surface as well as in the deep ocean. However, the surface water in the Arctic Ocean is not depleted enough, due to the absence of highly depleted precipitation and snowfall. A model–data mismatch is also recognizable in the isotopic composition of the seawater–salinity relationship in midlatitudes that is mainly caused by the coarse grid resolution. Deep-ocean characteristics of the vertical water mass distribution in the Atlantic Ocean closely resemble observational data. The reconstructed δ18Oc at the sea surface shows a good agreement with measurements. However, the model–data fit is weaker when individual species are considered and deviations are most likely attributable to the habitat depth of the foraminifera. Overall, the newly developed stable water isotope package opens wide prospects for long-term simulations in a paleoclimatic context.
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Gugele, Sarah Maria, Jan Baer, Christina Spießl, et al. "Stable isotope values and trophic analysis of invasive three-spined stickleback in Upper Lake Constance points to significant piscivory." NeoBiota 87 (August 14, 2023): 73–102. http://dx.doi.org/10.3897/neobiota.87.100355.
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The three-spined stickleback Gasterosteus aculeatus was introduced into Lake Constance in the 1940s and occupied a limited range until late 2012. Since then the species has expanded from a solely littoral habitat in Upper Lake Constance, but now makes seasonal migrations into the pelagic zone. This behavioral change has been accompanied by a drastic increase in stickleback abundance. In order to integrate information about feeding of sticklebacks in Upper Lake Constance over two consecutive years, stomach content analysis was combined with seasonal stable isotope analysis on two types of tissue (muscle and liver). Isotope values were also obtained for zooplankton, whitefish larvae and eggs. We calculated the contribution of potential food sources for sticklebacks’ diet using a Bayesian mixing model (SIMMR). Furthermore, we determined stickleback trophic position, and δ15N and δ13C values were compared with those of other fish species of Lake Constance. The results of the Bayesian model as well as the stomach content analysis showed clear evidence of stickleback predation on fish eggs and larvae. Stickleback δ15N values were elevated during winter and comparable to those of piscivorous pike, while δ15N values of zooplankton were reduced, and those of whitefish larvae were similar to those of sticklebacks after accounting trophic fractionation of N isotopes. Trophic position calculations further identified sticklebacks as piscivorous, while the δ13C values of the liver and stomach content analysis suggests that a benthic-pelagic species pair may exist in Lake Constance. These findings support the hypotheses that sticklebacks in Lake Constance can display piscivorous feeding behaviour on sympatric fish species, most likely whitefish larvae and eggs.
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Kurle, Carolyn M. "Stable-isotope ratios of blood components from captive northern fur seals (Callorhinus ursinus) and their diet: applications for studying the foraging ecology of wild otariids." Canadian Journal of Zoology 80, no. 5 (2002): 902–9. http://dx.doi.org/10.1139/z02-069.
Full textAbstract:
Stable nitrogen and carbon isotope ratios (13C/12C and 15N/14N, respectively) of plasma, serum, clotted red blood cells, and unclotted red blood cells from six captive northern fur seals (Callorhinus ursinus) and two fish species in their diet, Atlantic herring (Clupea harengus) and Icelandic capelin (Mallotus villosus), were measured. The δ15N values from the fur seal blood components ranged from 15.5 ± 0.1 (mean ± SE; all RBCs) to 16.7 ± 0.1 (plasma), and δ13C values ranged from 18.3 ± 0.1 (serum) to 17.5 ± 0.1 (clotted RBCs). Fur seal blood components had higher δ15N and δ13C values than their diet. Mean enrichments of 15N between fur seal RBCs and plasma/serum and their prey were +4.1 and +5.2, respectively, while mean 13C enrichments were +0.6 (serum), +1.0 (plasma), and +1.3 to +1.4 (all RBCs). Fur seal blood components did not differ in δ15N or δ13C between the sexes. One female (Baabs) was pregnant at the time of sampling and was resampled 4 months later, when she was approximately 3 months post parturient. The δ15N values of the blood components taken from Baabs during pregnancy were all higher by 0.6 (unclotted RBCs) to 1.3 (plasma) than those of samples taken during lactation, while her δ13C values were nearly the same (RBCs) for the two time periods or lower during lactation by 0.5 (serum) and 0.7 (plasma). This study was the first to analyze isotope ratios of blood components from captive fur seals and their prey. The subsequent establishment of fractionation values between captive fur seals and their diet can be used to interpret trophic level and habitat usage of otariids feeding in the wild.
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Yoshimura, T., A. Suzuki, and N. Iwasaki. "Mechanism of O and C isotope fractionation in magnesian calcite skeletons of <i>Octocorallia</i> corals and an implication on their calcification response to ocean acidification." Biogeosciences Discussions 12, no. 1 (2015): 389–412. http://dx.doi.org/10.5194/bgd-12-389-2015.
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Abstract. Coral calcification is strongly dependent on both the pH and the dissolved inorganic carbon (DIC) of the calcifying fluid. Skeletal oxygen and carbon isotope fractionation of high-Mg calcite skeletons of \\textit{Octocorallia} corals directly record the biological manipulation on sources of DIC in response to environmental changes. The coral skeletons were enriched in light isotopes (16O and 12C) relative to the expected values based on habitat environmental parameters and Mg/Ca of the skeletons. The differences between the expected and observed values ranged from −4.66 to −1.53 for δ18O and from −7.34 to −1.75 for δ13C. The large variability cannot be explained by the ambient environment, the contribution of metabolic carbon, or the precipitation rate of the skeleton. Therefore, the most plausible explanation for the observed O and C isotope differences in high-Mg calcite coral skeletons is the existence of two carbon sources, aqueous carbon dioxide in the calcifying fluid and dissolved inorganic carbon in seawater. Positive correlations of B/Ca with δ18O and δ13C suggest that skeletal isotopic compositions are enriched in light isotopes when conditions are less alkaline. Therefore, the relative contribution of isotopically heavy DIC from seawater through the skeleton and pericellular channels decreases under the reduced pH of the extracytoplasmic calcifying fluid. Our data suggest an even stronger biological effect under lower pH. Skeletal δ18O and δ13C values record the response of the sources of DIC in the coral calcifying fluids to ambient seawater pH. These changes give insight into how ocean acidification impacts the physiological mechanisms as well as the pH offset between calcifying fluid and seawater in response to ocean acidification.
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Brügmann, G., J. Krause, T. C. Brachert, et al. "Chemical composition of modern and fossil Hippopotamid teeth and implications for paleoenvironmental reconstructions and enamel formation – Part 2: Alkaline earth elements as tracers of watershed hydrochemistry and provenance." Biogeosciences Discussions 9, no. 3 (2012): 3645–91. http://dx.doi.org/10.5194/bgd-9-3645-2012.
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Abstract. For reconstructing environmental change in terrestrial realms the geochemistry of fossil bioapatite in bones and teeth is among the most promising applications. This study demonstrates that alkaline earth elements in enamel of Hippopotamids, in particular Ba and Sr are tracers for water provenance and hydrochemistry. The studied specimens are molar teeth from Hippopotamids found in modern and fossil lacustrine settings of the Western Branch of the East African Rift system (Lake Kikorongo, Lake Albert, and Lake Malawi) and from modern fluvial environments of the Nile River. Concentrations in enamel vary by ca. two orders of magnitude for Ba (120–9336 μg g−1) as well as for Sr (9–2150 μg g−1). Concentration variations in enamel are partly induced during post-mortem alteration and during amelogenesis, but the major contribution originates from the variable water chemistry in the habitats of the Hippopotamids which is dominated by the lithologies and weathering processes in the watershed areas. Amelogenesis causes a distinct distribution of Ba and Sr in modern and fossil enamel, in that element concentrations increase along profiles from the outer rim towards the enamel-dentin junction by a factor of 1.3–1.5. These elements are well correlated with MgO and Na2O in single specimens, thus suggesting that their distribution is determined by a common, single process. Presuming that the shape of the tooth is established at the end of the secretion process and apatite composition is in equilibrium with the enamel fluid, the maturation process can be modeled by closed system Rayleigh crystallization. Enamel from many Hippopotamid specimens has Sr/Ca and Ba/Ca which are typical for herbivores, but the compositions extend well into the levels of plants and carnivores. Within enamel from single specimens these element ratios covary and provide a specific fingerprint of the Hippopotamid habitat. All specimens together, however, define subparallel trends with different Ba/Sr ranging from 0.1 to 3. This ratio varies on spatial and temporal scales and traces provenance signals as well as the fractionation of the elements in the hydrological cycle. Thus, Sr concentrations and Ba/Sr in enamel differentiate between habitats having basaltic or Archean crustal rocks as the ultimate sources of Sr and Ba. The provenance signal is modulated by climate change. In Miocene to Pleistocene enamel from the Lake Albert region, Ba/Sr decreases systematically with time from about 2 to 0.5. This trend can be correlated with changes in climate from humid to arid in vegetation from C3 to C4 biomass as well as with increasing evaporation of the lake water. The most plausible explanation is that with time, Ba mobility decreased relative to that of Sr. This can arise if preferential adsorption of Ba to clay and Fe-oxide-hydroxide is related to increasing aridification. Additionally, weathering solutions and lake water can become increasingly alkaline and barite becomes stable. In this case, Ba will be preferentially deposited on the watershed of Lake Albert and rivers with low Ba/Sr will feed the habitats of the Hippopotamids.
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Kelly, Jeffrey F. "Stable isotopes of carbon and nitrogen in the study of avian and mammalian trophic ecology." Canadian Journal of Zoology 78, no. 1 (2000): 1–27. http://dx.doi.org/10.1139/z99-165.
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Differential fractionation of stable isotopes of carbon during photosynthesis causes C4 plants and C3 plants to have distinct carbon-isotope signatures. In addition, marine C3 plants have stable-isotope ratios of carbon that are intermediate between C4 and terrestrial C3 plants. The direct incorporation of the carbon-isotope ratio (13C/12C) of plants into consumers' tissues makes this ratio useful in studies of animal ecology. The heavy isotope of nitrogen (15N) is preferentially incorporated into the tissues of the consumer from the diet, which results in a systematic enrichment in nitrogen-isotope ratio (15N/14N) with each trophic level. Consequently, stable isotopes of nitrogen have been used primarily to assess position in food chains. The literature pertaining to the use of stable isotopes of carbon and nitrogen in animal trophic ecology was reviewed. Data from 102 studies that reported stable-isotope ratios of carbon and (or) nitrogen of wild birds and (or) mammals were compiled and analyzed relative to diet, latitude, body size, and habitat moisture. These analyses supported the predicted relationships among trophic groups. Carbon-isotope ratios differed among species that relied on C3, C4, and marine food chains. Likewise, nitrogen-isotope ratios were enriched in terrestrial carnivorous mammals relative to terrestrial herbivorous mammals. Also, marine carnivores that ate vertebrates had nitrogen-isotope ratios that were enriched over the ratios of those that ate invertebrates. Data from the literature also indicated that (i) the carbon-isotope ratio of carnivore bone collagen was inversely related to latitude, which was likely the result of an inverse relationship between the proportion of carbon in the food chain that was fixed by C4 plants and latitude; (ii) seabirds and marine mammals from northern oceans had higher nitrogen-isotope ratios than those from southern oceans; (iii) the nitrogen-isotope ratios of terrestrial mammals that used xeric habitats were higher than the ratios of those that used mesic habitats, indicating that water stress can have important effects on the nitrogen-isotope ratio; (iv) there was no relationship between body mass and nitrogen-isotope ratio for either bone collagen or muscle of carnivores; and (v) there was linear covariation between stable-isotope ratios of carbon and nitrogen in marine food chains (but not in terrestrial C3 or C4 food chains), which is likely a product of increases in carbon-isotope ratio with trophic level in marine food chains. Differences in stable-isotope composition among trophic groups were detected despite variation attributable to geographic location, climate, and analytical techniques, indicating that these effects are large and pervasive. Consequently, as knowledge of the distribution of stable isotopes of carbon and nitrogen increases, they will probably become an increasingly important tool in the study of avian and mammalian trophic ecology.
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Schupp, Peter J., Claudia Kohlert-Schupp, Susanna Whitefield, et al. "Cancer Chemopreventive and Anticancer Evaluation of Extracts and Fractions from Marine Macro- and Microorganisms Collected from Twilight Zone Waters around Guam[1]." Natural Product Communications 4, no. 12 (2009): 1934578X0900401. http://dx.doi.org/10.1177/1934578x0900401222.
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The cancer chemopreventive and cytotoxic properties of 50 extracts derived from Twilight Zone (50–150 m) sponges, gorgonians and associated bacteria, together with 15 extracts from shallow water hard corals, as well as 16 fractions derived from the methanol solubles of the Twilight Zone sponge Suberea sp, were assessed in a series of bioassays. These assays included: Induction of quinone reductase (QR), inhibition of TNF-α activated nuclear factor kappa B (NFκB), inhibition of aromatase, interaction with retinoid X receptor (RXR), inhibition of nitric oxide (NO) synthase, inhibition 2,2-diphenyl-1-picrylhydrazyl radical scavenging (DPPH), and inhibition of HL-60 and MCF-7 cell proliferation. The results of these assays showed that at least 10 extracts and five fractions inhibited NFκB by greater than 60%, two extracts and two fractions inhibited DPPH by more than 50%, nine extracts and two fractions affected the survival of HL-60 cells, no extracts or fractions affected RXR, three extracts and six fractions affected quinone reductase (QR), three extracts and 12 fractions significantly inhibited aromatase, four extracts and five fractions inhibited nitric oxide synthase, and one extract and no fractions inhibited the growth of MCF-7 cells by more than 95%. These data revealed the tested samples to have many and varied activities, making them, as shown with the extract of the Suberea species, useful starting points for further fractionation and purification. Moreover, the large number of samples demonstrating activity in only one or sometimes two assays accentuates the potential of the Twilight Zone, as a largely unexplored habitat, for the discovery of selectively bioactive compounds. The overall high hit rate in many of the employed assays is considered to be a significant finding in terms of “normal” hit rates associated with similar samples from shallower depths.
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Gugele, Sarah Maria, Jan Baer, Christina Spießl, et al. "Stable isotope values and trophic analysis of invasive three-spined stickleback in Upper Lake Constance points to significant piscivory." NeoBiota 87 (August 14, 2023): 73–102. https://doi.org/10.3897/neobiota.87.100355.
Full textAbstract:
The three-spined stickleback Gasterosteus aculeatus was introduced into Lake Constance in the 1940s and occupied a limited range until late 2012. Since then the species has expanded from a solely littoral habitat in Upper Lake Constance, but now makes seasonal migrations into the pelagic zone. This behavioral change has been accompanied by a drastic increase in stickleback abundance. In order to integrate information about feeding of sticklebacks in Upper Lake Constance over two consecutive years, stomach content analysis was combined with seasonal stable isotope analysis on two types of tissue (muscle and liver). Isotope values were also obtained for zooplankton, whitefish larvae and eggs. We calculated the contribution of potential food sources for sticklebacks' diet using a Bayesian mixing model (SIMMR). Furthermore, we determined stickleback trophic position, and δ<sup>15</sup>N and δ<sup>13</sup>C values were compared with those of other fish species of Lake Constance. The results of the Bayesian model as well as the stomach content analysis showed clear evidence of stickleback predation on fish eggs and larvae. Stickleback δ<sup>15</sup>N values were elevated during winter and comparable to those of piscivorous pike, while δ<sup>15</sup>N values of zooplankton were reduced, and those of whitefish larvae were similar to those of sticklebacks after accounting trophic fractionation of N isotopes. Trophic position calculations further identified sticklebacks as piscivorous, while the δ<sup>13</sup>C values of the liver and stomach content analysis suggests that a benthic-pelagic species pair may exist in Lake Constance. These findings support the hypotheses that sticklebacks in Lake Constance can display piscivorous feeding behaviour on sympatric fish species, most likely whitefish larvae and eggs.
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Manske, Ann K., Jens Glaeser, Marcel M. M. Kuypers, and Jörg Overmann. "Physiology and Phylogeny of Green Sulfur Bacteria Forming a Monospecific Phototrophic Assemblage at a Depth of 100 Meters in the Black Sea." Applied and Environmental Microbiology 71, no. 12 (2005): 8049–60. http://dx.doi.org/10.1128/aem.71.12.8049-8060.2005.
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ABSTRACT The biomass, phylogenetic composition, and photoautotrophic metabolism of green sulfur bacteria in the Black Sea was assessed in situ and in laboratory enrichments. In the center of the western basin, bacteriochlorophyll e (BChl e) was detected between depths of 90 and 120 m and reached maxima of 54 and 68 ng liter−1. High-pressure liquid chromatography analysis revealed a dominance of farnesyl esters and the presence of four unusual geranyl ester homologs of BChl e. Only traces of BChl e (8 ng liter−1) were found at the northwestern slope of the Black Sea basin, where the chemocline was positioned at a significantly greater depth of 140 m. Stable carbon isotope fractionation values of farnesol indicated an autotrophic growth mode of the green sulfur bacteria. For the first time, light intensities in the Black Sea chemocline were determined employing an integrating quantum meter, which yielded maximum values between 0.0022 and 0.00075 μmol quanta m−2 s−1 at the top of the green sulfur bacterial layer around solar noon in December. These values represent by far the lowest values reported for any habitat of photosynthetic organisms. Only one 16S rRNA gene sequence type was detected in the chemocline using PCR primers specific for green sulfur bacteria. This previously unknown phylotype groups with the marine cluster of the Chlorobiaceae and was successfully enriched in a mineral medium containing sulfide, dithionite, and freshly prepared yeast extract. Under precisely controlled laboratory conditions, the enriched green sulfur bacterium proved to be capable of exploiting light intensities as low as 0.015 μmol quanta m−2 s−1 for photosynthetic 14CO2 fixation. Calculated in situ doubling times of the green sulfur bacterium range between 3.1 and 26 years depending on the season, and anoxygenic photosynthesis contributes only 0.002 to 0.01% to total sulfide oxidation in the chemocline. The stable population of green sulfur bacteria in the Black Sea chemocline thus represents the most extremely low-light-adapted and slowest-growing type of phototroph known to date.
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Chela-Flores, J., A. Cicuttin, M. L. Crespo, and C. Tuniz. "Biogeochemical fingerprints of life: earlier analogies with polar ecosystems suggest feasible instrumentation for probing the Galilean moons." International Journal of Astrobiology 14, no. 3 (2014): 427–34. http://dx.doi.org/10.1017/s1473550414000391.
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AbstractWe base our search for the right instrumentation for detecting biosignatures on Europa on the analogy suggested by the recent work on polar ecosystems in the Canadian Arctic at Ellesmere Island. In that location sulphur patches (analogous to the Europan patches) are accumulating on glacial ice lying over saline springs rich in sulphate and sulphide. Their work reinforces earlier analogies in Antarctic ecosystems that are appropriate models for possible habitats that will be explored by the European Space Agency JUpiter ICy Moons Explorer (JUICE) mission to the Jovian System. Its Jupiter Ganymede Orbiter (JGO) will include orbits around Europa and Ganymede. The Galileo orbital mission discovered surficial patches of non-ice elements on Europa that were widespread and, in some cases possibly endogenous. This suggests the possibility that the observed chemical elements in the exoatmosphere may be from the subsurface ocean. Spatial resolution calculations of Cassidy and co-workers are available, suggesting that the atmospheric S content can be mapped by a neutral mass spectrometer, now included among the selected JUICE instruments. In some cases, large S-fractionations are due to microbial reduction and disproportionation (although sometimes providing a test for ecosystem fingerprints, even though with Sim – Bosak – Ono we maintain that microbial sulphate reduction large sulphur isotope fractionation does not require disproportionation. We address the question of the possible role of oxygen in the Europan ocean. Instrument issues are discussed for measuring stable S-isotope fractionations up to the known limits in natural populations of δ34 ≈ −70‰. We state the hypothesis of a Europa anaerobic oceanic population of sulphate reducers and disproportionators that would have the effect of fractionating the sulphate that reaches the low-albedo surficial regions. This hypothesis is compatible with the time-honoured expectation of Kaplan and co-workers (going back to the 1960s) that the distribution range of 32S/34S in analysed extra-terrestrial material appears to be narrower than the isotopic ratio of H, C or N and may be the most reliable for estimating biological effects. In addition, we discuss the necessary instruments that can test our biogenic hypothesis. First of all we hasten to clarify that the last-generation miniaturized mass spectrometer we discuss in the present paper are capable of reaching the required accuracy of ‰ for the all-important measurements with JGO of the thin atmospheres of the icy satellites. To implement the measurements, we single out miniature laser ablation time-of-flight mass spectrometers that are ideal for the forthcoming JUICE probing of the exoatmospheres, ionospheres and, indirectly, surficial low-albedo regions. Ganymede's surface, besides having ancient dark terrains covering about one-third of the total surface, has bright terrains of more recent origin, possibly due to some internal processes, not excluding biological ones. The geochemical test could identify bioindicators on Europa and exclude them on its large neighbour by probing relatively recent bright terrains on Ganymede's Polar Regions.
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Kastelle, CR, TE Helser, BJ Laurel, LA Copeman, KR Stone, and JL McKay. "Oxygen isotope fractionation in otoliths: experimental results from four North Pacific and Arctic gadid species." Marine Ecology Progress Series 686 (March 24, 2022): 159–75. http://dx.doi.org/10.3354/meps13985.
Full textAbstract:
High-latitude climate warming is expected to have wide-ranging effects on habitats, ecosystems, and the fish species that occupy them. Not all fish species will be able to adapt to increasing temperatures. We investigated oxygen isotope fractionation in fish otoliths and its relationship to environmental temperature and thermal histories of individual fish. Fish from 4 gadid species, Gadus macrocephalus, Boreogadus saida, Eleginus gracilis, and G. chalcogrammus, representing North Pacific and Arctic regions, were reared in a range of controlled temperatures (0-20°C). We estimated 4 new species-specific otolith oxygen isotope fractionation equations, a relationship between otolith δ18O and temperature (T) in the form δ18Oo - δ18Ow = m × T°C + b and also in a second form using the fractionation factor α: 1000 ln α = a × (1000 TK-1) + c, where o is otolith, w is water, and m, b, a and c are regression coefficients. In using the first form, B. saida was the most unique among the 4 species, with the steepest slope (-0.23) and the highest intercept (32.99‰ Vienna PeeDee Belemnite [VPDB]). G. macrocephalus had the lowest slope (-0.17) and the lowest intercept (31.76‰ [VPDB]). Results of an ANCOVA test indicated that the 4 fractionation equations were not statistically different (F = 2.25, p > 0.087). However, when we applied the 4 new fractionation equations to δ18Oo measured in wild-caught B. saida otoliths, the species-�specific fractionation equation resulted in the closest match between measured and predicted water temperatures. These new fractionation equations represent new tools for investigating temperature effects on fish biota and will also improve paleotemperature reconstruction, especially for high-latitude species.
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Preuss, I., C. Knoblauch, J. Gebert, and E. M. Pfeiffer. "Improved quantification of microbial CH<sub>4</sub> oxidation efficiency in arctic wetland soils using carbon isotope fractionation." Biogeosciences 10, no. 4 (2013): 2539–52. http://dx.doi.org/10.5194/bg-10-2539-2013.
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Abstract. Permafrost-affected tundra soils are significant sources of the climate-relevant trace gas methane (CH4). The observed accelerated warming of the arctic will cause deeper permafrost thawing, followed by increased carbon mineralization and CH4 formation in water-saturated tundra soils, thus creating a positive feedback to climate change. Aerobic CH4 oxidation is regarded as the key process reducing CH4 emissions from wetlands, but quantification of turnover rates has remained difficult so far. The application of carbon stable isotope fractionation enables the in situ quantification of CH4 oxidation efficiency in arctic wetland soils. The aim of the current study is to quantify CH4 oxidation efficiency in permafrost-affected tundra soils in Russia's Lena River delta based on stable isotope signatures of CH4. Therefore, depth profiles of CH4 concentrations and δ13CH4 signatures were measured and the fractionation factors for the processes of oxidation (αox) and diffusion (αdiff) were determined. Most previous studies employing stable isotope fractionation for the quantification of CH4 oxidation in soils of other habitats (such as landfill cover soils) have assumed a gas transport dominated by advection (αtrans = 1). In tundra soils, however, diffusion is the main gas transport mechanism and diffusive stable isotope fractionation should be considered alongside oxidative fractionation. For the first time, the stable isotope fractionation of CH4 diffusion through water-saturated soils was determined with an αdiff = 1.001 &amp;pm; 0.000 (n = 3). CH4 stable isotope fractionation during diffusion through air-filled pores of the investigated polygonal tundra soils was αdiff = 1.013 &amp;pm; 0.003 (n = 18). Furthermore, it was found that αox differs widely between sites and horizons (mean αox = 1.017 ± 0.009) and needs to be determined on a case by case basis. The impact of both fractionation factors on the quantification of CH4 oxidation was analyzed by considering both the potential diffusion rate under saturated and unsaturated conditions and potential oxidation rates. For a submerged, organic-rich soil, the data indicate a CH4 oxidation efficiency of 50% at the anaerobic–aerobic interface in the upper horizon. The improved in situ quantification of CH4 oxidation in wetlands enables a better assessment of current and potential CH4 sources and sinks in permafrost-affected ecosystems and their potential strengths in response to global warming.
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Chunlei Song, Xiuyun Cao, Yiyong Zhou, and N. V. Shadrin. "Filamentous green algae, extracellular alkaline phosphatases and some features of the phosphorus cycle in ponds." Marine Biological Journal 2, no. 1 (2017): 66–78. http://dx.doi.org/10.21072/mbj.2017.02.1.07.
Full textAbstract:
Filamentous green algae (FGA) may reach high biomass and play a very important functional role in productivity and nutrient cycling in the different water bodies. Their extracellular alkaline phosphatase activity may be an important player in the phosphorus cycle. Currently, there is intensive development of green algae in various freshwater and marine waterbodies, which creates problems for people's activities and necessitates its investigation. Filamentous green algae in four Chinese and Crimean (Russia) shallow freshwater ponds were in focus of this study. The dissolved phosphorus fraction in pond water, algal pigment level, activity and kinetic properties of alkaline phosphatase were evaluated in water column and cell membrane of filamentous green algae. Microalgal taxa were identified in the plankton samples. Species composition and density of FGA in the studied ponds were different. Two ponds had more than 50 % coverage of a water surface by FGA and its wet biomass more than 100 g∙m-2. Two others were with wet biomass less than 2 g∙m-2. In ponds with low FGA biomass, the soluble reactive phosphorus concentration exhibited considerably low level with less than 10 µg∙L-1, and the dissolved organic phosphorus comprised the largest phosphorus fraction, averaging 23.1 µg∙L-1 and ranged from 20.8 to 25.4 µg∙L-1. However, in ponds with high FGA biomass, particulate phosphorus was the major component, which contributes 45.8 % and 56.7 % of total phosphorus, respectively. Size fractionation of extracellular alkaline phosphatase activity in water column expressed spatial heterogeneity, which corresponded with biomass of FGA. The response of extracellular alkaline phosphatase activity to different phosphate concentration in water column was completely distinct from that in the cell membrane of FGA, the last of which represented the significantly inhibition effect to high phosphate concentration. The significant inhibition of alkaline phosphatase activity in cell membrane of FGA by phosphate in water may validate that FGA growth was limited by phosphorus. The contradiction between a low concentration of soluble reactive phosphorus and high FGA biomass may indicate that there was high speed nutrient cycling, probably, due to the alkaline phosphatase activity. Excreting exo-alkaline phosphatases, FGA, microalgae and bacteria accelerate phosphorus cycling through different mechanisms, and this may increase their development. In ponds with high FGA biomass, many of bacteria are responsible for regeneration of nutrients, which then consuming by FGA. Those bacteria also may concurrently restrict a microalgae development, such as unicellular Chlorophyta species. As an example, Cladophora provides habitat for different species of epibionts (bacteria and microalgae, primarily diatoms), and sustains of strong mutualistic alga-bacterium interactions. Therefore, the problem of excessive FGA growth should not be considered in isolation, but in a whole-ecosystem context.
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Preuss, I., C. Knoblauch, J. Gebert, and E. M. Pfeiffer. "Improved quantification of microbial CH<sub>4</sub> oxidation efficiency in Arctic wetland soils using carbon isotope fractionation." Biogeosciences Discussions 9, no. 12 (2012): 16999–7035. http://dx.doi.org/10.5194/bgd-9-16999-2012.
Full textAbstract:
Abstract. Permafrost-affected tundra soils are significant sources of the climate-relevant trace gas methane (CH4). The observed accelerated warming of the Arctic will cause a deeper permafrost thawing followed by increased carbon mineralization and CH4 formation in water saturated tundra soils which might cause a positive feedback to climate change. Aerobic CH4 oxidation is regarded as the key process reducing CH4 emissions from wetlands, but quantification of turnover rates has remained difficult so far. The application of carbon stable isotope fractionation enables the in situ quantification of CH4 oxidation efficiency in arctic wetland soils. The aim of the current study is to quantify CH4 oxidation efficiency in permafrost-affected tundra soils in Russia's Lena River Delta based on stable isotope signatures of CH4. Therefore, depth profiles of CH4 concentrations and δ13CH4-signatures were measured and the fractionation factors for the processes of oxidation (αox) and diffusion (αdiff) were determined. Most previous studies employing stable isotope fractionation for the quantification of CH4 oxidation in soils of other habitats (e.g. landfill cover soils) have assumed a gas transport dominated by advection (αtrans = 1). In tundra soils, however, diffusion is the main gas transport mechanism, aside from ebullition. Hence, diffusive stable isotope fractionation has to be considered. For the first time, the stable isotope fractionation of CH4 diffusion through water-saturated soils was determined with an αdiff = 1.001 ± 0.000 (n = 3). CH4 stable isotope fractionation during diffusion through air-filled pores of the investigated polygonal tundra soils was αdiff = 1.013 ± 0.003 (n = 18). Furthermore, it was found that αox differs widely between sites and horizons (mean αox, = 1.017 ± 0.009) and needs to be determined individually. The impact of both fractionation factors on the quantification of CH4 oxidation was analyzed by considering both the potential diffusion rate under saturated and unsaturated conditions and potential oxidation rates. For a submerged organic rich soil, the data indicate a CH4 oxidation efficiency of 50% at the anaerobic-aerobic interface in the upper horizon. The improved in situ quantification of CH4 oxidation in wetlands enables a better assessment of current and potential CH4 sources and sinks in permafrost affected ecosystems and their potential strengths in response to global warming.
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Kawagucci, Shinsuke, Yohei Matsui, Akiko Makabe, et al. "Hydrogen and carbon isotope fractionation factors of aerobic methane oxidation in deep-sea water." Biogeosciences 18, no. 19 (2021): 5351–62. http://dx.doi.org/10.5194/bg-18-5351-2021.
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Abstract. Isotope fractionation factors associated with various biogeochemical processes are important in ensuring the reliable use of isotope tracers in biogeosciences at large. Methane is a key component of the subsurface biosphere and a notable greenhouse gas, making the accurate evaluation of methane cycles, including microbial methanotrophy, imperative. Although the isotope fractionation factors associated with methanotrophy have been examined under various conditions, the dual-isotope fractionation factors of aerobic methanotrophy in oxic seawater remain unclear. Here, we investigated hydrogen and carbon isotope ratios of methane as well as the relevant biogeochemical parameters and microbial community compositions in hydrothermal plumes in the Okinawa Trough. Methanotrophs were found to be abundant in plumes above the Hatoma Knoll vent site, and we succeeded in simultaneously determining hydrogen and carbon isotope fractionation factors associated with the aerobic oxidation of methane (εH=49.4±5.0 ‰, εC=5.2±0.4 ‰) – the former being the first of its kind ever reported. This εH value is comparable with values reported from terrestrial ecosystems but clearly lower than those from aerobic and anaerobic methanotroph enrichment cultures, as well as incubations of methanotrophic isolates. The covariation factor between δ13CCH4 and δDCH4, Λ (9.4 or 8.8 determined using two different methods), was consistent with those from methanotrophic isolate incubations. These values are valuable for understanding dynamics of methane cycling in the marine realm, and future applications of the approach to other habitats with methanotrophic activity will help reveal whether the small εH value observed is a ubiquitous feature across all marine systems.
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Scriber, Kevin E., Christine A. M. France, and Fatimah L. C. Jackson. "Assessing the Impact of Biodiversity (Species Evenness) on the Trophic Position of an Invasive Species (Apple Snails) in Native and Non-Native Habitats Using Stable Isotopes." Sustainability 15, no. 11 (2023): 8560. http://dx.doi.org/10.3390/su15118560.
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Invasive apple snails negatively impact non-native habitats and human well-being. Here, the trophic position of Pomacea canaliculata in native habitats (Maldonado, Uruguay) and non-native habitats (Hangzhou, China and Hawaii, USA) are compared. Detritus samples and tissue samples from apple snails were collected in all sites. Trophic levels were calculated as the difference between the mean δ15N values of detritus samples and corresponding apple snail tissue samples, divided by the mean δ15N fractionation for nitrogen per trophic level in freshwater habitats. The mean δ15N values of detritus in sites served as a baseline (i.e., zero trophic level), allowing direct comparisons. Linear regression analysis established a correlation between species evenness and apple snail trophic level (R2 = 0.8602) in line with a Pearson’s product-moment correlation value (−0.83) and 95% confidence interval (−0.87, −0.77). Normal quartile plots indicated two normally distributed subsets of apple snail trophic-level data: (1) a biodiverse subset containing the Uruguayan and Chinese lake sites and (2) the homogenized Hawaiian and Chinese creek sites. A precipice value for species evenness (separating biodiversity from homogenization), between (3.7) and (2.4), once descended to or surpassed separates statistically distinct, normal distributions of invasive apple snail trophic-level data from diverse versus homogenized habitats.
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Santhirasegaram, Sinthujah, Suranga R. Wickramarachchi, Renuka N. Attanayake, et al. "A Novel Cytotoxic Compound From the Endolichenic Fungus, Xylaria psidii Inhabiting the Lichen, Amandinea medusulina." Natural Product Communications 15, no. 7 (2020): 1934578X2093301. http://dx.doi.org/10.1177/1934578x20933017.
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The lichen host, Amandinea medusulina, collected from mangrove habitats in Sri Lanka, and its associated endolichenic fungi were isolated and identified by rDNA-ITS sequence analysis and morphological features. One of the fungal strains frequently isolated from the lichen thalli was identified as Xylaria psidii. This study aimed at the isolation and identification of the cytotoxic compounds present in this fungus. Secondary metabolites of X. psidii were first extracted into ethyl acetate and subsequently subjected to bioassay-guided fractionation to isolate the bioactive compounds. Sulforhodamine B assay against a lung cancer (NCI-H292) cell line was used to determine the differential cytotoxic activity. Bioassay-guided fractionation led to the isolation of an active compound, SS/02/29/08, showing moderate cytotoxicity (IC50 = 27.2 µg/mL). Its structure was elucidated by IR, 1D- and 2D-NMR, and 13C-NMR spectrophotometry and MS, in combination with HRMS, 13C NMR, HSQC, HMBC, and DQF-COSY. The structure of SS/02/29/08 was determined as ( Z)-3-{(3-acetyl-2-hydroxyphenyl)diazenyl}-2,4-dihydroxybenzaldehyde and identified as a new compound. This novel compound has promising differential cytotoxic activity against human lung cancer cell line (NCI-H292).
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Herzka, Sharon Z., and G. Joan Holt. "Changes in isotopic composition of red drum (Sciaenops ocellatus) larvae in response to dietary shifts: potential applications to settlement studies." Canadian Journal of Fisheries and Aquatic Sciences 57, no. 1 (2000): 137–47. http://dx.doi.org/10.1139/f99-174.
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The stable isotope composition of larval fish tissues may serve as a chemical tracer of recent settlement due to food web differences among planktonic and demersal habitats. We present the background for the utilization of δ13C and δ15N to trace settlement of red drum (Sciaenops ocellatus), an estuarine-dependent species. The effect of ontogeny and temperature on the relative contribution of growth and metabolic turnover to changes in isotopic composition was examined by simulating dietary shifts in the laboratory. Fractionation was examined as a function of size and the effect of food deprivation was evaluated. Published growth rates were used to estimate the time period within which the isotopic composition of a new food source should be reflected in larval tissues. In response to dietary shifts, larvae exhibited quick changes in δ13C and δ15N in a pattern closely resembling predictions based on growth alone. Fractionation values were about +1 for δ13C and +1.6 for δ15N. There was no effect of 4 days of food deprivation on δ13C and δ15N. Given the fast growth rates reported for newly settled red drum, their isotopic composition should exhibit a shift within 1-2 days and stabilize about 10 days following settlement.
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Könneke, Martin, Julius S. Lipp, and Kai-Uwe Hinrichs. "Carbon isotope fractionation by the marine ammonia-oxidizing archaeon Nitrosopumilus maritimus." Organic Geochemistry 48 (May 3, 2012): 21–24. https://doi.org/10.1016/j.orggeochem.2012.04.007.
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Abstract Ammonia-oxidizing archaea (AOA) are abundant and widely distributed microorganisms in aquatic and terrestrial habitats. By catalyzing the first and rate limiting step in nitrification, these chemolithoautotrophs play a significant role in the global nitrogen cycle and contribute to primary production. Here, the carbon isotopic fractionation relative to inorganic carbon source was determined for bulk biomass, biphytanes and polar lipid bound sugars of a marine AOA pure culture. Bulk biomass and biphytanes from <em>Nitrosopumilus maritimus</em> showed identical carbon isotope fractionation (<em>ε</em><sub>DIC/bulk</sub> and <em>ε</em><sub>DIC/byphytanes</sub>) of ca. −20‰. The glycoside head groups were mainly glucose, mannose and inositol, and exhibited different carbon isotopic composition. In general, these monosaccharides were enriched in <sup>13</sup>C (<em>ε</em> −6.1‰ to −13.8‰) relative to bulk biomass and biphytanes. The fact that the carbon isotope composition of the biphytanes reflected that of the bulk biomass of <em>N. maritimus</em> suggests that the depletion of <sup>13</sup>C in both biomass and biphytanes resulted mainly from the carbon isotope discrimination by the bicarbonate-fixing enzyme in the autotrophic hydroxypropionate/hydroxybutyrate cycle. Our results further revealed that lipid compounds represent suitable biomarkers for determining δ<sup>13</sup>C values of archaeal ammonia oxidizers without biosynthetic correction.
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Bell-Tilcock, Miranda, Carson A. Jeffres, Andrew L. Rypel, et al. "Biogeochemical processes create distinct isotopic fingerprints to track floodplain rearing of juvenile salmon." PLOS ONE 16, no. 10 (2021): e0257444. http://dx.doi.org/10.1371/journal.pone.0257444.
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Floodplains represent critical nursery habitats for a variety of fish species due to their highly productive food webs, yet few tools exist to quantify the extent to which these habitats contribute to ecosystem-level production. Here we conducted a large-scale field experiment to characterize differences in food web composition and stable isotopes (δ¹³C, δ¹⁵N, δ³⁴S) for salmon rearing on a large floodplain and adjacent river in the Central Valley, California, USA. The study covered variable hydrologic conditions including flooding (1999, 2017), average (2016), and drought (2012–2015). In addition, we determined incorporation rates and tissue fractionation between prey and muscle from fish held in enclosed locations (experimental fields, cages) at weekly intervals. Finally, we measured δ³⁴S in otoliths to test if these archival biominerals could be used to reconstruct floodplain use. Floodplain-reared salmon had a different diet composition and lower δ13C and δ³⁴S (δ¹³C = -33.02±2.66‰, δ³⁴S = -3.47±2.28‰; mean±1SD) compared to fish in the adjacent river (δ¹³C = -28.37±1.84‰, δ³⁴S = +2.23±2.25‰). These isotopic differences between habitats persisted across years of extreme droughts and floods. Despite the different diet composition, δ¹⁵N values from prey items on the floodplain (δ¹⁵N = 7.19±1.22‰) and river (δ¹⁵N = 7.25±1.46‰) were similar, suggesting similar trophic levels. The food web differences in δ13C and δ³⁴S between habitats were also reflected in salmon muscle tissue, reaching equilibrium between 24–30 days (2014, δ¹³C = -30.74±0.73‰, δ³⁴S = -4.6±0.68‰; 2016, δ¹³C = -34.74 ±0.49‰, δ³⁴S = -5.18±0.46‰). δ³⁴S measured in sequential growth bands in otoliths recorded a weekly time-series of shifting diet inputs, with the outermost layers recording time spent on the floodplain (δ³⁴S = -5.60±0.16‰) and river (δ³⁴S = 3.73±0.98‰). Our results suggest that δ¹³C and δ³⁴S can be used to differentiate floodplain and river rearing habitats used by native fishes, such as Chinook Salmon, across different hydrologic conditions and tissues. Together these stable isotope analyses provide a toolset to quantify the role of floodplains as fish habitats.
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Burian, Alfred, Jens M. Nielsen, Thomas Hansen, Rafael Bermudez, and Monika Winder. "The potential of fatty acid isotopes to trace trophic transfer in aquatic food-webs." Philosophical Transactions of the Royal Society B: Biological Sciences 375, no. 1804 (2020): 20190652. http://dx.doi.org/10.1098/rstb.2019.0652.
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Compound-specific isotope analyses (CSIA) of fatty acids (FA) constitute a promising tool for tracing energy flows in food-webs. However, past applications of FA-specific carbon isotope analyses have been restricted to a relatively coarse food-source separation and mainly quantified dietary contributions from different habitats. Our aim was to evaluate the potential of FA-CSIA to provide high-resolution data on within-system energy flows using algae and zooplankton as model organisms. First, we investigated the power of FA-CSIA to distinguish among four different algae groups, namely cyanobacteria, chlorophytes, haptophytes and diatoms. We found substantial within-group variation but also demonstrated that δ 13 C of several FA (e.g. 18:3 ω 3 or 18:4 ω 3) differed among taxa, resulting in group-specific isotopic fingerprints. Second, we assessed changes in FA isotope ratios with trophic transfer. Isotope fractionation was highly variable in daphnids and rotifers exposed to different food sources. Only δ 13 C of nutritionally valuable poly-unsaturated FA remained relatively constant, highlighting their potential as dietary tracers. The variability in fractionation was partly driven by the identity of food sources. Such systematic effects likely reflect the impact of dietary quality on consumers' metabolism and suggest that FA isotopes could be useful nutritional indicators in the field. Overall, our results reveal that the variability of FA isotope ratios provides a substantial challenge, but that FA-CSIA nevertheless have several promising applications in food-web ecology. This article is part of the theme issue ‘The next horizons for lipids as ‘trophic biomarkers’: evidence and significance of consumer modification of dietary fatty acids’.
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Chen, Yongle, Brent R. Helliker, Xianhui Tang, Fang Li, Youping Zhou, and Xin Song. "Stem water cryogenic extraction biases estimation in deuterium isotope composition of plant source water." Proceedings of the National Academy of Sciences 117, no. 52 (2020): 33345–50. http://dx.doi.org/10.1073/pnas.2014422117.
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The hydrogen isotope ratio of water cryogenically extracted from plant stem samples (δ2Hstem_CVD) is routinely used to aid isotope applications that span hydrological, ecological, and paleoclimatological research. However, an increasing number of studies have shown that a key assumption of these applications—that δ2Hstem_CVD is equal to the δ2H of plant source water (δ2Hsource)—is not necessarily met in plants from various habitats. To examine this assumption, we purposedly designed an experimental system to allow independent measurements of δ2Hstem_CVD, δ2Hsource, and δ2H of water transported in xylem conduits (δ2Hxylem) under controlled conditions. Our measurements performed on nine woody plant species from diverse habitats revealed a consistent and significant depletion in δ2Hstem_CVD compared with both δ2Hsource and δ2Hxylem. Meanwhile, no significant discrepancy was observed between δ2Hsource and δ2Hxylem in any of the plants investigated. These results cast significant doubt on the long-standing view that deuterium fractionation occurs during root water uptake and, alternatively, suggest that measurement bias inherent in the cryogenic extraction method is the root cause of δ2Hstem_CVD depletion. We used a rehydration experiment to show that the stem water cryogenic extraction error could originate from a dynamic exchange between organically bound deuterium and liquid water during water extraction. In light of our finding, we suggest caution when partitioning plant water sources and reconstructing past climates using hydrogen isotopes, and carefully propose that the paradigm-shifting phenomenon of ecohydrological separation (“two water worlds”) is underpinned by an extraction artifact.
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Rodríguez-Minguela, Carlos M., Juha H. A. Apajalahti, Benli Chai, James R. Cole, and James M. Tiedje. "Worldwide Prevalence of Class 2 Integrases outside the Clinical Setting Is Associated with Human Impact." Applied and Environmental Microbiology 75, no. 15 (2009): 5100–5110. http://dx.doi.org/10.1128/aem.00133-09.
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ABSTRACT An intI-targeted PCR assay was optimized to evaluate the frequency of partial class 2-like integrases relative to putative, environmental IntI elements in clone libraries generated from 17 samples that included various terrestrial, marine, and deep-sea habitats with different exposures to human influence. We identified 169 unique IntI phylotypes (≤98% amino acid identity) relative to themselves and with respect to those previously described. Among these, six variants showed an undescribed, extended, IntI-specific additional domain. A connection between human influence and the dominance of IntI-2-like variants was also observed. IntI phylotypes 80 to 99% identical to class 2 integrases comprised ∼70 to 100% (n = 65 to 87) of the IntI elements detected in samples with a high input of fecal waste, whereas IntI2-like sequences were undetected in undisturbed settings and poorly represented (1 to 10%; n = 40 to 79) in environments with moderate or no recent fecal or anthropogenic impact. Eleven partial IntI2-like sequences lacking the signature ochre 179 codon were found among samples of biosolids and agricultural soil supplemented with swine manure, indicating a wider distribution of potentially functional IntI2 variants than previously reported. To evaluate IntI2 distribution patterns beyond the usual hosts, namely, the Enterobacteriaceae, we coupled PCR assays targeted at intI and 16S rRNA loci to G+C fractionation of total DNA extracted from manured cropland. IntI2-like sequences and 16S rRNA phylotypes related to Firmicutes (Clostridium and Bacillus) and Bacteroidetes (Chitinophaga and Sphingobacterium) dominated a low-G+C fraction (∼40 to 45%), suggesting that these groups could be important IntI2 hosts in manured soil. Moreover, G+G fractionation uncovered an additional set of 36 novel IntI phylotypes (≤98% amino acid identity) undetected in bulk DNA and revealed the prevalence of potentially functional IntI2 variants in the low-G+C fraction.
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Nishiyama, Masaya, Keishi Senoo, Hidenori Wada, and Satoshi Matsumoto. "Identification of soil micro-habitats for growth, death and survival of a bacterium, γ-1,2,3,4,5,6-hexachlorocyclohexane-assimilatingSphingomonas paucimobilis, by fractionation of soil." FEMS Microbiology Letters 101, no. 3 (1992): 145–50. http://dx.doi.org/10.1111/j.1574-6968.1992.tb05770.x.
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NISHIYAMA, M. "Identification of soil micro-habitats for growth, death and survival of a bacterium, ?-1,2,3,4,5,6-hexachlorocyclohexane-assimilating Sphingomonas paucimobilis, by fractionation of soil." FEMS Microbiology Reviews 101, no. 3 (1992): 145–50. http://dx.doi.org/10.1016/0168-6445(92)90010-s.
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Nishiyama, Masaya, Keishi Senoo, Hidenori Wada та Satoshi Matsumoto. "Identification of soil micro-habitats for growth, death and survival of a bacterium, γ-1,2,3,4,5,6-hexachlorocyclohexane-assimilating Sphingomonas paucimobilis, by fractionation of soil". FEMS Microbiology Ecology 10, № 3 (1992): 145–50. http://dx.doi.org/10.1111/j.1574-6941.1992.tb01650.x.
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Nishiyama, M. "Identification of soil micro-habitats for growth, death and survival of a bacterium, γ-1,2,3,4,5,6-hexachlorocyclohexane-assimilating Sphingomonas paucimobilis, by fractionation of soil". FEMS Microbiology Letters 101, № 3 (1992): 145–50. http://dx.doi.org/10.1016/0378-1097(92)90810-b.
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Nishiyama, M. "Identification of soil micro-habitats for growth, death and survival of a bacterium, γ-1,2,3,4,5,6-hexachlorocyclohexane-assimilating Sphingomonas paucimobilis, by fractionation of soil". FEMS Microbiology Ecology 101, № 3 (1992): 145–50. http://dx.doi.org/10.1016/0168-6496(92)90030-w.
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Deias, Claudia, Adriano Guido, Rossana Sanfilippo, et al. "Elemental Fractionation in Sabellariidae (Polychaeta) Biocement and Comparison with Seawater Pattern: A New Environmental Proxy in a High-Biodiversity Ecosystem?" Water 15, no. 8 (2023): 1549. http://dx.doi.org/10.3390/w15081549.
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The polychaete worm Sabellaria alveolata builds shallow-water aggregates of tubes by agglutinating sands using a secreted glue. Sabellarid bioconstructions represent fragile and dynamic habitats that host numerous associated organisms, playing a key ecological role. A two-year study on bioconstructions from three Sicilian sites (Simeto, Portopalo, and Falconara) investigated the balance between reef status and environmental parameters through a geochemical comparison of biocement tube portions and the surrounding waters. Water pollution by heavy metals, which is monitored in marine waters, is a result of river, domestic, and industrial discharges. The major constituents from the biocements of the three sites showed concentrations comparable to those in the seawater, while trace elements (Cr, Ni, Cu, Zn, and As) showed concentrations significantly higher than the mean seawater composition. These similar trends confirm a close dependence between the presence of trace elements (metals) in the seawater and the subsequent bioaccumulation in the biocement produced by the worm. The results also showed that Ca and Mg are fractionated by biocement independent of their water concentrations, in contrast to the trace elements. Further studies addressing the biomineralization processes and the relative fractionation of trace elements in Sabellaria biocement will allow it to be validated as a valuable proxy for short- and long-term environmental studies.
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Lovell, John T., Alice H. MacQueen, Sujan Mamidi, et al. "Genomic mechanisms of climate adaptation in polyploid bioenergy switchgrass." Nature 590, no. 7846 (2021): 438–44. http://dx.doi.org/10.1038/s41586-020-03127-1.
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AbstractLong-term climate change and periodic environmental extremes threaten food and fuel security1and global crop productivity2–4. Although molecular and adaptive breeding strategies can buffer the effects of climatic stress and improve crop resilience5, these approaches require sufficient knowledge of the genes that underlie productivity and adaptation6—knowledge that has been limited to a small number of well-studied model systems. Here we present the assembly and annotation of the large and complex genome of the polyploid bioenergy crop switchgrass (Panicum virgatum). Analysis of biomass and survival among 732 resequenced genotypes, which were grown across 10 common gardens that span 1,800 km of latitude, jointly revealed extensive genomic evidence of climate adaptation. Climate–gene–biomass associations were abundant but varied considerably among deeply diverged gene pools. Furthermore, we found that gene flow accelerated climate adaptation during the postglacial colonization of northern habitats through introgression of alleles from a pre-adapted northern gene pool. The polyploid nature of switchgrass also enhanced adaptive potential through the fractionation of gene function, as there was an increased level of heritable genetic diversity on the nondominant subgenome. In addition to investigating patterns of climate adaptation, the genome resources and gene–trait associations developed here provide breeders with the necessary tools to increase switchgrass yield for the sustainable production of bioenergy.
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Novotná Jaroměřská, Tereza, Jakub Trubač, Krzysztof Zawierucha, Lenka Vondrovicová, Miloslav Devetter, and Jakub D. Žárský. "Stable isotopic composition of top consumers in Arctic cryoconite holes: revealing divergent roles in a supraglacial trophic network." Biogeosciences 18, no. 5 (2021): 1543–57. http://dx.doi.org/10.5194/bg-18-1543-2021.
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Abstract. Arctic cryoconite holes represent highly biologically active aquatic habitats on the glacier surface characterized by the dynamic nature of their formation and functioning. The most common cryoconite apex consumers are the cosmopolitan invertebrates – tardigrades and rotifers. Several studies have highlighted the potential relevance of tardigrades and rotifers to cryoconite holes' ecosystem functioning. However, due to the dominant occurrence of prokaryotes, these consumers are usually out of the major scope of most studies aimed at understanding biological processes on glaciers. The aim of this descriptive study is to present pioneering data on isotopic composition of tardigrades, rotifers and cryoconite from three High Arctic glaciers in Svalbard and discuss their role in a cryoconite hole trophic network. We found that tardigrades have lower δ15N values than rotifers, which indicates different food requirements or different isotopic fractionation of both consumers. The δ13C values revealed differences between consumers and organic matter in cryoconite among glaciers. However, the mechanistic explanation of these variations requires further investigation focused on the particular diet of cryoconite consumers and their isotopic ratio. Our study introduces the first observation of carbon and nitrogen stable isotopic composition of top consumers in cryoconite holes analysed by an improved method for cryoconite sample processing, paving the way for further studies of the supraglacial trophic network.
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Martínez, Kevin A., Chiara Lauritano, Dana Druka, et al. "Amphidinol 22, a New Cytotoxic and Antifungal Amphidinol from the Dinoflagellate Amphidinium carterae." Marine Drugs 17, no. 7 (2019): 385. http://dx.doi.org/10.3390/md17070385.
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Due to the unique biodiversity and the physical-chemical properties of their environment, marine microorganisms have evolved defense and signaling compounds that often have no equivalent in terrestrial habitats. The aim of this study was to screen extracts of the dinoflagellate Amphidinium carterae for possible bioactivities (i.e., anticancer, anti-inflammatory, anti-diabetes, antibacterial and antifungal properties) and identify bioactive compounds. Anticancer activity was evaluated on human lung adenocarcinoma (A549), human skin melanoma (A2058), human hepatocellular carcinoma (HepG2), human breast adenocarcinoma (MCF7) and human pancreas carcinoma (MiaPaca-2) cell lines. Antimicrobial activities were evaluated against Gram-positive bacteria (Staphylococcus aureus MRSA and MSSA), Gram-negative bacteria (i.e., Escherichia coli and Klebsiella pneumoniae), Mycobacterium tuberculosis and the fungus Aspergillus fumigatus. The results indicated moderate biological activities against all the cancer cells lines and microorganisms tested. Bioassay-guided fractionation assisted by HRMS analysis allowed the detection of one new and two known amphidinols that are potentially responsible for the antifungal and cytotoxic activities observed. Further isolation, purification and structural elucidation led to a new amphidinol, named amphidinol 22. The planar structure of the new compound was determined by analysis of its HRMS and 1D and 2D NMR spectra. Its biological activity was evaluated, and it displayed both anticancer and antifungal activities.
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Nge, Francis J., and Hans Lambers. "Reassessing protocarnivory – how hungry are triggerplants?" Australian Journal of Botany 66, no. 4 (2018): 325. http://dx.doi.org/10.1071/bt18059.
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Stylidium species (triggerplants) are claimed to be protocarnivorous based on the presence of glandular hairs, observations of trapped small organisms, and induction of proteinase activity. However, these traits might serve alternative functions. We aimed to re-assess and quantify the degree of carnivory for Stylidium species in an ecological context, by comparing the natural abundance (δ15N) of Stylidium species with co-occurring carnivorous (Drosera species) and non-carnivorous plants in their natural habitats. We hypothesised that the δ15N signature of Stylidium species would more closely match co-occurring carnivorous plant species than their non-carnivorous counterparts if they rely on captured organisms as a nutrient source, since there is an increase in fractionation by 3–5 ‰ per trophic level. Our results show that the Stylidium species sampled had δ15N signatures that matched more closely with co-occurring non-carnivorous plants than with carnivorous Drosera species. This does not support the claim that they rely on captured organisms as a nitrogen source, or the source is negligible. Other studies have shown that protocarnivorous species have a δ15N signature that is more similar to that of co-occurring carnivorous than that of non-carnivorous species. Therefore, our findings question the protocarnivory status of Stylidium species.