Academic literature on the topic 'Protiste'
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Journal articles on the topic "Protiste"
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Jing, H., E. Rocke, L. Kong, X. Xia, H. Liu, and M. R. Landry. "Protist communities in a marine oxygen minimum zone off Costa Rica by 454 pyrosequencing." Biogeosciences Discussions 12, no. 16 (August 20, 2015): 13483–509. http://dx.doi.org/10.5194/bgd-12-13483-2015.
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Abstract. Marine planktonic protists, including microalgae and protistan grazers, are an important contributor to global primary production and carbon and mineral cycles, however, little is known about their population shifts along the oxic-anoxic gradient in the water column. We used 454 pyrosequencing of the 18S rRNA gene and gene transcripts to study the community composition of whole and active protists throughout a water column in the Costa Rica Dome, where a stable oxygen minimum zone (OMZ) exists at a depth of 400~700 m. A clear shift of protist composition from photosynthetic Dinoflagellates in the surface to potential parasitic Dinoflagellates and Ciliates in the deeper water was revealed along the vertical profile at both rRNA and rDNA levels. Those protist groups recovered only at the rDNA level represent either lysed aggregates sinking from the upper waters or potential hosts for parasitic groups. UPGMA clustering demonstrated that total and active protists in the anoxic core of OMZ (550 m) were distinct from those in other water depths. The reduced community diversity and presence of a parasitic/symbiotic trophic lifestyle in the OMZ, especially the anoxic core, suggests that OMZs can exert a selective pressure on protist communities. Such changes in community structure and a shift in trophic lifestyle could result in a modulation of the microbial loop and associated biogeochemical cycling.
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Andersen, Robert A. "What to do with protists?" Australian Systematic Botany 11, no. 2 (1998): 185. http://dx.doi.org/10.1071/sb97011.
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The definition of ‘protists’ has changed over time, once including all living organisms which were neither plant nor animal, now including a multitude of organisms that cannot be assembled into a monophyletic group. Protists were once subdivided into algae, fungi and protozoa, based upon mode of nutrition, and further subdivided based upon the dominate life history stage (e.g. flagellate, amoeboid, coccoid), however, studies during the past 40 years have shown that these divisions are artificial. Electron microscopic studies, as well as a revival of the Endosymbiotic Theory for the origin of organelles, have caused a demolition of classical protistan taxonomy. Numerous new higher level taxa were described. Molecular studies, especially nucleotide sequence comparisons, have provided a new means for determining phylogenetic relationships. Although these molecular studies have not succeeded in providing an overall consensus classification for the protists, many advances have been made. It now appears that the protists are, at best, a grade, not a clade, and they do not form a monophyletic taxon (i.e. the Kingdom Protista cannot be recognised as a natural group). Despite this taxonomic limitation, there are advantages to maintaining the protists as an assemblage for ecological, biomedical or economic reasons. The biodiversity of protists is discussed along with remarks on their ecological and economic significance.
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Klepka, Verônica, Maria Julia Corazza, and Fagner De Souza. "John Hogg (1800-1869) e a descrição do quarto reino natural: Primigenum." História da Ciência e Ensino: construindo interfaces 18 (November 28, 2018): 125–39. http://dx.doi.org/10.23925/2178-2911.2018v18p125-139.
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ResumoAté o século XIX, organismos que, por indefinição ou por falta de caracteres distintivos claros, compartilhavam características com as plantas e/ou com os animais estavam distribuídos nos reinos vegetal ou animal. Novos conhecimentos tornaram necessária a criação de um agrupamento separado. Em 1860, o naturalista John Hogg revisa a separação feita pelo paleontólogo Richard Owen propondo modificações e a criação do quarto reino da natureza: o Primigenum, foco de debates conceituais ao longo de todo século XX até chegar ao que hoje conhecemos como Reino Protista. A tradução do trabalho de Hogg, lido para a Associação Britânica, em Oxford, no dia 28 de junho de 1860, é aqui apresentada. Palavras-Chave: Classificação biológica; Protistas; Seres Vivos.AbstractUntil the nineteenth century, organisms, of indefiniteness or lack of clear distinctive characters, shared features with the plants and / or animals were distributed in the plant and animal kingdom. New knowledge made necessary the creation of a separate grouping. In 1860, naturalist John Hogg review the separation maked for paleontologist Richard Owen proposing modifications and the creation of the fourth kingdom of nature: the Primigenum, focus of conceptual debates throughout the twentieth century to get to what we know today as the Kingdom Protist. The translation of Hogg, work read to British Association, in Oxford, on June 28, 1860, is presented here.Keywords: Biologic classification; Protists; Living Beings
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Zou, Songbao, Qianqian Zhang, and Jun Gong. "Comparative Transcriptomics Reveals Distinct Gene Expressions of a Model Ciliated Protozoan Feeding on Bacteria-Free Medium, Digestible, and Digestion-Resistant Bacteria." Microorganisms 8, no. 4 (April 13, 2020): 559. http://dx.doi.org/10.3390/microorganisms8040559.
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Bacterivory is an important ecological function of protists in natural ecosystems. However, there are diverse bacterial species resistant to protistan digestion, which reduces the carbon flow to higher trophic levels. So far, a molecular biological view of metabolic processes in heterotrophic protists during predation of bacterial preys of different digestibility is still lacking. In this study, we investigated the growth performance a ciliated protozoan Tetrahymena thermophila cultivated in a bacteria-free Super Proteose Peptone (SPP) medium (control), and in the media mixed with either a digestion-resistant bacterial species (DRB) or a digestible strain of E. coli (ECO). We found the protist population grew fastest in the SPP and slowest in the DRB treatment. Fluorescence in situ hybridization confirmed that there were indeed non-digested, viable bacteria in the ciliate cells fed with DRB, but none in other treatments. Comparative analysis of RNA-seq data showed that, relative to the control, 637 and 511 genes in T. thermophila were significantly and differentially expressed in the DRB and ECO treatments, respectively. The protistan expression of lysosomal proteases (especially papain-like cysteine proteinases), GH18 chitinases, and an isocitrate lyase were upregulated in both bacterial treatments. The genes encoding protease, glycosidase and involving glycolysis, TCA and glyoxylate cycles of carbon metabolic processes were higher expressed in the DRB treatment when compared with the ECO. Nevertheless, the genes for glutathione metabolism were more upregulated in the control than those in both bacterial treatments, regardless of the digestibility of the bacteria. The results of this study indicate that not only bacterial food but also digestibility of bacterial taxa modulate multiple metabolic processes in heterotrophic protists, which contribute to a better understanding of protistan bacterivory and bacteria-protists interactions on a molecular basis.
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Chauvier, G., and J. Mortier-Gabet. "Culture d’un Protiste pathogène isolé du système génital et de divers organes de Primates." Annales de Parasitologie Humaine et Comparée 62, no. 4 (1987): 294–300. http://dx.doi.org/10.1051/parasite/1987624294.
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Oliverio, Angela M., Stefan Geisen, Manuel Delgado-Baquerizo, Fernando T. Maestre, Benjamin L. Turner, and Noah Fierer. "The global-scale distributions of soil protists and their contributions to belowground systems." Science Advances 6, no. 4 (January 2020): eaax8787. http://dx.doi.org/10.1126/sciadv.aax8787.
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Protists are ubiquitous in soil, where they are key contributors to nutrient cycling and energy transfer. However, protists have received far less attention than other components of the soil microbiome. We used amplicon sequencing of soils from 180 locations across six continents to investigate the ecological preferences of protists and their functional contributions to belowground systems. We complemented these analyses with shotgun metagenomic sequencing of 46 soils to validate the identities of the more abundant protist lineages. We found that most soils are dominated by consumers, although parasites and phototrophs are particularly abundant in tropical and arid ecosystems, respectively. The best predictors of protist composition (primarily annual precipitation) are fundamentally distinct from those shaping bacterial and archaeal communities (namely, soil pH). Some protists and bacteria co-occur globally, highlighting the potential importance of these largely undescribed belowground interactions. Together, this study allowed us to identify the most abundant and ubiquitous protists living in soil, with our work providing a cross-ecosystem perspective on the factors structuring soil protist communities and their likely contributions to soil functioning.
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Zölffel, Michael, and Oliver Skibbe. "Rediscovery of the multiflagellated protist Paramastix conifera Skuja 1948 (Protista incertae sedis)." Nova Hedwigia 65, no. 1-4 (May 15, 1997): 443–52. http://dx.doi.org/10.1127/nova.hedwigia/65/1997/443.
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Jagus, Rosemary, Tsvetan R. Bachvaroff, Bhavesh Joshi, and Allen R. Place. "Diversity of Eukaryotic Translational Initiation Factor eIF4E in Protists." Comparative and Functional Genomics 2012 (2012): 1–21. http://dx.doi.org/10.1155/2012/134839.
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The greatest diversity of eukaryotic species is within the microbial eukaryotes, the protists, with plants and fungi/metazoa representing just two of the estimated seventy five lineages of eukaryotes. Protists are a diverse group characterized by unusual genome features and a wide range of genome sizes from 8.2 Mb in the apicomplexan parasiteBabesia bovisto 112,000-220,050 Mb in the dinoflagellateProrocentrum micans. Protists possess numerous cellular, molecular and biochemical traits not observed in “text-book” model organisms. These features challenge some of the concepts and assumptions about the regulation of gene expression in eukaryotes. Like multicellular eukaryotes, many protists encode multiple eIF4Es, but few functional studies have been undertaken except in parasitic species. An earlier phylogenetic analysis of protist eIF4Es indicated that they cannot be grouped within the three classes that describe eIF4E family members from multicellular organisms. Many more protist sequences are now available from which three clades can be recognized that are distinct from the plant/fungi/metazoan classes. Understanding of the protist eIF4Es will be facilitated as more sequences become available particularly for the under-represented opisthokonts and amoebozoa. Similarly, a better understanding of eIF4Es within each clade will develop as more functional studies of protist eIF4Es are completed.
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Shimada, Keisuke, Nathan Lo, Osamu Kitade, Akane Wakui, and Kiyoto Maekawa. "Cellulolytic Protist Numbers Rise and Fall Dramatically in Termite Queens and Kings during Colony Foundation." Eukaryotic Cell 12, no. 4 (February 2, 2013): 545–50. http://dx.doi.org/10.1128/ec.00286-12.
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ABSTRACTAmong the best-known examples of mutualistic symbioses is that between lower termites and the cellulolytic flagellate protists in their hindguts. Although the symbiosis in worker termites has attracted much attention, there have been only a few studies of protists in other castes. We have performed the first examination of protist population dynamics in queens and kings during termite colony foundation. Protist numbers, as well as measurements of hindgut and reproductive tissue sizes, were undertaken at five time points over 400 days in incipient colonies ofReticulitermes speratus, as well as in other castes of mature colonies of this species. We found that protist numbers increased dramatically in both queens and kings during the first 50 days of colony foundation but began to decrease by day 100, eventually disappearing by day 400. Hindgut width followed a pattern similar to that of protist numbers, while ovary and testis widths increased significantly only at day 400. Kings were found to contain higher numbers of protists than queens in incipient colonies, which may be linked to higher levels of nutrient transfer from kings to queens than vice versa, as is known in some other termite species. Protists were found to be abundant in soldiers from mature colonies but absent in neotenics. This probably reflects feeding of soldiers by workers via proctodeal trophallaxis and of reproductives via stomodeal trophallaxis. The results reveal the dynamic nature of protist numbers during colony foundation and highlight the trade-offs that exist between reproduction and parental care during this critical phase of the termite life cycle.
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Chauvier, G., and J. Mortier-Gabet. "Découverte d’un Protiste parasite, paraissant apparenté aux Acrasiés, dans l’appareil génital et certains organes de Primates." Annales de Parasitologie Humaine et Comparée 61, no. 4 (1986): 401–10. http://dx.doi.org/10.1051/parasite/1986614401.
Full textDissertations / Theses on the topic "Protiste"
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El, Safadi Dima. "Epidémiologie moléculaire, facteurs de risque de transmission et pathogénicité du protiste parasite Blastocystis sp." Thesis, Lille 2, 2014. http://www.theses.fr/2014LIL2S045/document.
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Blastocystis est un protozoaire anaérobie trouvé dans le tube digestif de l’homme et de nombreux animaux. Il est à ce jour le parasite intestinal le plus fréquemment retrouvé dans les selles humaines. Dix-sept sous-types (ST1 à ST17) ont été décrits en se basant sur la comparaison des séquences du gène de l’ARNr 18S. L’infection à Blastocystis est associée à une variété de troubles gastro-intestinaux et plusieurs études suggèrent une corrélation entre la pathogénicité et le ST du parasite. Trois différents axes de recherche ont été développés. Le premier s’est focalisé sur la prévalence et la biodiversité génétique de ce parasite dans les populations humaines. Des études épidémiologiques ont été menées en France et au Liban mais aussi en Afrique en réalisant la première enquête au Sénégal. Le sous-typage des isolats a été réalisé par PCR en temps réel en ciblant un domaine du gène de l’ARNr 18S suivi d’un séquençage direct du produit de PCR. Au Liban, la prévalence de Blastocystis était de 20% dans la population globale avec une corrélation entre le ST1 et le développement de symptômes gastro-intestinaux. Dans le même pays, cette prévalence dépassait les 60% chez des patients symptomatiques et des écoliers. Au Sénégal, la prévalence observée est la plus importante jamais décrite pour ce parasite puisqu’elle atteignait 100% dans une population d’une centaine d’enfants vivant en milieu rural. Ces données soulignent l’impact socioéconomique de la blastocystose dans les pays en développement où les conditions sanitaires sont souvent précaires. En France, une prévalence importante de 18% a pourtant été observée dans une large étude épidémiologique englobant des patients présentant ou non des symptômes et suivis dans 11 hôpitaux répartis sur tout le territoire français. Le ST3 est prédominant suivi des STs 1, 2 et 4 comme dans une majorité de pays à travers le monde. Le deuxième axe s’est concentré sur l’identification des facteurs de risque de transmission de Blastocystis à l’homme. Le parasite a été recherché dans les selles de vaches et de patients ainsi que dans des échantillons d’eau consommée par l’homme et les animaux dans une région géographique limitée du Nord Liban. 30% des échantillons humains, 69% des échantillons d'eau et 80% des échantillons de bovins étaient positifs pour le parasite. Le ST3 était prédominant dans les échantillons humains et d’eau suivi des ST1, ST2 et ST4. Par contre, ST10 et ST14 étaient prédominants chez les bovins mais ces deux STs n’ont pas été retrouvés dans les autres types d’échantillons. Pour expliquer l'absence des ST10 et ST14 dans ces échantillons, une transmission de ces STs par contact direct entre les bovins et/ou l'absence de formes kystiques transmissibles pour ces STs ont été proposées. Ce parasite a aussi été recherché dans les selles de nombreux groupes d’animaux du zoo de La Palmyre en France. Nous avons montré que près de 40% des selles analysés étaient positives pour Blastocystis et identifié de nouveaux réservoirs d'infections pour l’homme chez les carnivores. La prévalence du parasite atteignait 60% chez les primates chez lesquels les ST1 à ST5 identifiés sont identiques à ceux observés chez l'homme confirmant la faible spécificité d’hôte de ces STs. Dans une autre étude, la prévalence de Blastocystis était de seulement 3,5% dans une population de chiens en France suggérant que cet animal n'est pas un hôte naturel de Blastocystis. Enfin, pour clarifier la pathogénicité de ce parasite, le troisième axe de mes travaux a souligné le caractère invasif de Blastocystis dans un cas de péritonite appendiculaire chez une fillette de 9 ans de retour du Maroc. Seul Blastocystis a été détecté dans les selles, l’appendice, le liquide péritonéal et le sac de Douglas de cette patiente. Une gastro-entérite s’est de plus déclarée simultanément chez 26 membres de la famille de l'enfant suggérant une épidémie qui pourrait trouver son origine dans la consommation commune d’une eau contaminéeBlastocystis sp. is an anaerobic parasitic protozoa found in the digestive tract of humans and numerous animals. To date, it is the most common intestinal parasite found in human feces with worldwide distribution. Seventeen subtypes (ST1-ST17) have been described based on the comparison of SSU rRNA gene sequences. Blastocystis infection is associated with various gastrointestinal disorders and many studies suggest a correlation between Blastocystis STs and pathogenicity. My work was developed on three different topics. The first concerned the prevalence and the genetic biodiversity of the parasite in human populations. Epidemiological studies were conducted in France and Lebanon but also in Africa by performing the first survey of this parasite in Senegal. Subtyping of the isolates was performed by real-time PCR targeting a domain of the SSU rRNA gene followed by direct sequencing of the PCR product. In Lebanon, the prevalence of Blastocystis reached 20% in the general population and we demonstrated a correlation between ST1 infection and the presence of symptoms. In the same country, this prevalence was 60% in schoolchildren and patients presenting gastrointestinal symptoms. Strikingly, the prevalence of Blastocystis in a population of one hundred children living in a rural area reached 100% in Senegal and more than half of the infected children by the parasite presented gastrointestinal disorders. These latter studies highlighted the socioeconomic impact of blastocystosis in developing countries with poor hygiene sanitation. In France, a large-scale molecular epidemiological study was performed including patients presenting or not gastrointestinal symptoms. Stool samples were collected during winter and summer in 11 hospitals spread all over the French territory. We observed a high prevalence of Blastocystis in the french population with an average of 18.2% and the predominance of ST3 followed by ST1, ST4 and ST2 as in numerous countries. We also identified seasonal variations since the average prevalence of the parasite is 13.6% in winter and 23.1% in summer. The second topic focused on the identification of the risk factors of Blastocystis transmission to humans. We searched this parasite in bovid and human stools as well as in drinking water samples consumed by bovids and breeders in a limited geographic area of North-Lebanon. 30% of human samples, 69% of water samples and 80% of bovid samples were positive for the parasite. Interestingly ST3 is predominant in human and water samples followed by ST1, ST2 and ST4. ST10 and ST14 were predominant in bovid but both STs are lacking in human and water samples. To explain the lack of ST10 and ST14 in human and water samples, we suggested a transmission of these STs occurring through direct contact between bovid and / or the absence of transmissible cystic forms of these STs. Furthermore, this parasite was searched in the stools of numerous animal groups in the zoo of La Palmyre in France. We showed that nearly 40% of the analyzed stools were positive for Blastocystis and identified new reservoirs of human infections in carnivores. The prevalence of the parasite reached 60% in primates in which the identified ST1 to ST5 are identical to those observed in humans confirming the limited host specificity of these STs. In another study, we showed that the prevalence of Blastocystis was of only 3.5% in a population of one hundred dogs in France suggesting that this pet is not a natural host of Blastocystis. Finally, to clarify the pathogenicity of this parasite, the third topic highlighted the invasive character of Blastocystis observed in a case of appendicular peritonitis in a 9-year old girl returning from Morocco. Only Blastocystis was detected in stools, appendix, peritoneal liquid and Douglas pouch of the patient. Interestingly, simultaneous gastroenteritis occurred in 26 members of the child’s family suggested an outbreak with contaminated water as probable origin
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Rodríguez, Giner Caterina. "Spatial, temporal and behavioral patterns of marine protists = Patrons espaials, temporals i de comportament dels protistes marins." Doctoral thesis, Universitat Politècnica de Catalunya, 2017. http://hdl.handle.net/10803/666998.
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The oceans are microbial-dominated ecosystems, where protists (single-celled eukaryotes) play fundamental roles performing multiple functions as primary producers, consumers, decomposers as well as trophic linkers in aquatic food webs. Due to their ecological relevance, it is important to characterize protist communities along temporal and spatial gradients to understand their biogeography and dynamics. This will allow us to infer the processes that drive the assembly of protist communities. In this dissertation, we focused in the study of natural protists communities aiming to understand their distributions and responses within different dimensions. We first focused in the temporal dimension, analyzing the dynamics of pico- and nanoeukaryotic communities, aiming to characterize the diverse strategies of their members and to determine seasonality. We identified an annual seasonal pattern in the protist community as well as in several composing taxa. Then, we addressed the spatial dimension, analyzing the changes in community composition along the water column in 13 stations distributed in the global ocean, exploring also the vertical variation in the relative metabolic activity of different taxa. Our results showed a clear vertical stratification of the community and indicated that the mesopelagic layer is the region with the highest metabolic activity. Another aim of this thesis was to explore the response of natural protists to chemical gradients. The ocean is a complex ecosystem with nutrients heterogeneously distributed along several patches, so there may be a lot of chemical gradients promoting diverse responses on marine microbes. For that purpose, we performed chemotactic experiments to identify individual responses towards different attractants within a natural protist community. The experimental results showed a preferential response towards some of the tested chemical cues, mainly bacterial exudates. Finally, since studies on microbial diversity generally use the relative abundances of phylotypes in a given sample, we explored the relationship between the latter relative abundances to cell abundances in several chosen taxa. In sum, this dissertation determines temporal and spatial patterns in protists communities as well as chemotactic preferences in different taxa, contributing to broaden our understanding of the structuring processes operating across temporal, spatial and behavioral dimensions in the protist world.Els oceans són ecosistemes dominats per microorganismes. Entre ells, els protistes (organismes eucariotes unicel·lulars) tenen un paper fonamental en diverses funcions imprescindibles per al sistema marí, principalment com a productors primaris i depredadors, i per tant juguen un paper clau en les xarxes tròfiques marines. Degut a la seva importància ecològica, es necessària la caracterització de les comunitats de protistes al llarg del temps i l'espai per tal d'entendre la seva dinàmica així com els seus patrons biogeogràfics. Això ens permetrà inferir els processos que governen l'estructura de les comunitats de protistes. En aquest context, la present tesi aborda la variabilitat de les comunitats naturals de protistes fent èmfasi en la seva distribució i resposta a diferents nivells. Primerament, ens hem centrat en la dimensió temporal, analitzant les dinàmiques de les comunitats de pico- i nanoeucariotes amb la finalitat de caracteritzar les diverses estratègies utilitzades pels diferents membres de la comunitat, així com també predir la recurrència dels patrons observats. S'ha identificat que, en conjunt, la comunitat de protistes segueix un patró anual, i també s'ha trobat un patró semblant per a algunes de les espècies, generalment les més abundants. Posteriorment, hem adreçat la dimensió espaial, avaluant com canvien les comunitats i l'activitat dels grups taxonòmics al llarg de la columna d'aigua en 13 estacions repartides pels diferents oceans de tot el món. S'ha observat que la comunitat està marcada per l'estratificació vertical i, a més, que la capa mesopelàgica és la regió on la majoria dels grups taxonòmics semblen estar més metabòlicament actius. Un altre nivell d'estudi d'aquesta tesi ha estat la resposta dels protistes davant la presència de senyals químics. L'oceà és un ecosistema complex on els nutrients estan distribuïts de manera heterogènia en diferents àrees, i això provoca l'existència de gradients químics que poden desencadenar diverses respostes dels microorganismes. Per tal d'identificar les respostes individuals dels protistes es van realitzar experiments de quimiotaxi. Els resultats experimentals van demostrar l'existencia d'una preferència d'alguns atractants químics com els exudats de bacteris, envers uns altres. Finalment, degut a que la majoria d'estudis de diversitat microbiana estan basats en abundàncies relatives de les diferents espècies presents a la mostra, s'han relacionat aquestes abundàncies amb les abundàncies reals. En resum, aquesta tesis profunditza en els patrons temporals i espaials de les comunitats de protistes, així com en les preferències quimiotàctiques dels diferents membres, contribuint a ampliar el nostre coneixement sobre els processos que estructuren les comunitats de protistes en la seva dimensió temporal, espaial i conductual.
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Castillo, de la Peña Yaiza M. "Interactions between marine picoeukaryotes and their viruses one cell at a time = Interacciones entre picoeucariotas marinos y sus virus célula a célula." Doctoral thesis, Universitat de Barcelona, 2019. http://hdl.handle.net/10803/668341.
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Marine viruses are key components of marine microbial communities, as they influence the cellular abundances and the community structure of microbes, participate in their genetic exchange, and intervene in the ocean biogeochemical cycles. Most studies dealing with the role of viruses in the marine environment have been done from a bulk community point of view, but going from the bulk community perspective to specific virus─host relationships is essential in order to understand the role of viruses in shaping a determined host community, in modifying host genomes, and ultimately in the release of organic compounds from the lysed cells. For this reason, in this thesis we implemented and applied different methodologies that are able to detect, visualize and quantify virus─host interactions in marine eukaryotes at the single cell level. We focused on picoeukaryotes (cells <3 µm) because they play crucial roles in marine food webs and biogeochemical cycles, and virus─host interactions in natural populations of these minute eukaryotes are largely unknown.
In the first chapter we combined previously developed techniques, used to assess prokaryotic host─phage interactions, to implement VirusFISH for detecting specific virus─host dynamics, using as a model system the photosynthetic picoeukaryote Ostreoccocus tauri and its virus OtV5. With the VirusFISH technique, we could also monitor the infection, as well as quantify the free viruses produced during the lysis of the host in a non-axenic culture, which allowed the calculation of the burst size. This study set the ground for the application of the VirusFISH technique to natural samples.
In the second chapter of this thesis, we applied VirusFISH to seawater samples from the Bay of Biscay (Cantabrian Sea) to study the dynamics of viral infection in natural populations of Ostreococcus along a seasonal cycle. We were able to quantify the percentage of cells infected over time, and compared these results with the transcriptional viral and host activities derived from metatranscriptomic data. This constitutes the first study where a specific viral─host interaction has been visualized and monitored over time in a natural system.
Picoeukaryotes in the ocean are prevalently uncultured, and thus, in the third chapter of this thesis we went an step further to unveil novel viral─host relationships in eukaryotic uncultured hosts. For this purpose, we mined single amplified genomes (SAGs) of picoeukaryotes obtained during the Tara Oceans expedition for viral signatures. We found that almost 60% of the cells analyzed presented an associated virus with narrow host specificity. Some of the viral sequences were widely distributed and some geographically constrained, and they were preferentially found at the deep chlorophyll maximum. Moreover, we found a mavirus virophage potentially integrated in four SAGs of two different lineages, suggesting the presence of virophages is more common than previously thought.
In summary, in this thesis we have implemented and used techniques that allow us to detect and monitor specific virus─host interactions, which is one of the major challenges in marine viral ecology. On the one hand, VirusFISH arises as a powerful technique that can be easily adapted to any host─virus system that has been genome-sequenced. On the other hand, the results obtained with the single cell genomics offer the opportunity to formulate hypothesis based on detected viral─host interactions in uncultured prevalent marine picoeukaryotes, which can be later tested using experimental approaches.Se han realizado muchos estudios sobre el rol de los virus en ambientes marinos desde el punto de vista de comunidad global, pero es esencial que vayamos hacía una visión más específica de relación virus─hospedador. Por ello, en esta tesis implementamos y aplicamos diferentes metodologías para estudiar interacciones virus─hospedador, centrándonos en picoeucariotas marinos ya que se conoce muy poco de ellos en poblaciones naturales. En el primer capítulo implementamos la técnica VirusFISH, permitiendo detectar dinámicas específicas virus─hospedador eucarióticos, usando como modelo Ostreococcus tauri y su virus OtV5. VirusFISH permitió monitorizar la infección, cuantificar en un cultivo no axénico los virus libres producidos durante la lisis y calcular el tamaño de explosión. Este estudio estableció la base para la aplicación de VirusFISH en muestras naturales. En el segundo capítulo aplicamos VirusFISH en muestras de agua natural para estudiar las dinámicas de infección en Ostreococcus. Cuantificamos el porcentaje de células infectadas durante un ciclo estacional y lo comparamos con las actividades transcripcionales de virus y Ostreococcus spp. Este constituye el primer estudio donde se visualiza y monitoriza una interacción específica virus─hospedador en el tiempo en un sistema natural. En el tercer capítulo descubrimos nuevas relaciones virus─hospedador en células no cultivadas, analizando genomas amplificados individuales de picoeucariotas, encontrando que la mayoría de las células presentaron al menos un virus. Estas secuencias víricas se encontraron preferentemente en el máximo profundo de clorofila, algunas de ellas ampliamente distribuidas por los océanos y otras constreñidas geográficamente. Además, encontramos un virofago mavirus potencialmente integrado en dos linajes distintos, sugiriendo que los virofagos son más comunes de lo que se pensaba. En resumen, hemos implementado y usado técnicas que nos han permitido detectar y monitorizar interacciones específicas virus─hospedador, uno de los mayores retos en la ecología microbiana marina. Por un lado, VirusFISH surge como una técnica potente que puede ser fácilmente adaptada a cualquier sistema virus─hospedador del cual tengamos el genoma secuenciado. Por otro lado, los resultados obtenidos con la genómica de célula individual muestran la oportunidad de formular hipótesis basadas en interacciones virus─hospedador detectadas en picoeucariotas marinos no cultivados, que pueden ser posteriormente testadas mediante aproximaciones experimentales.
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De, Schryver Vera. "Mixotrophy and pelagic ecosystem dynamics." Thesis, Brest, 2013. http://www.theses.fr/2013BRES0045/document.
Full textAbstract:
Les espèces protistes ont été traditionnellement classifiées comme des plantes ou des animaux en raison de l’absence ou présence des chloroplastes. L’état actuel de la connaissance indique qu’un grand nombre d’espèces protistes portent des chloroplastes mais que physiologiquement elles sont capables d’utiliser l’autotrophie (photosynthèse) ou l’hétérotrophie pour se nourrir. La combinaison de ces deux modes trophiques par une même cellule est nommée mixotrophie. Chez les protistes l’hétérotrophie peut s’effectuer soit par la consommation des particules par phagocytose, e.g. des proies bactériennes, ou bien par l’absorption des composants organiques dissouts, i.e. osmotrophie. La mixotrophie est de plus en plus décrit chez les protistes dans tous les habitats aquatiques. Les écologistes du plancton constatent la récurrence de la mixotrophie chez les formes traditionnelles « phyto»plancton et micro »zoo »plancton. Cependant, identifier et quantifier la mixotrophie reste toujours un défi méthodologique. Dans cette étude nous nous sommes intéressés à la mixotrophie chez les espèces phytoplanctoniques marines, en particulier à leur nutrition phagotrophique de proies bactériennes. Nous avons testé des techniques modernes afin d’identifier la mixotrophie dans des cellules phytoplanctoniques. La technique cytogénétique d’hybridation in situ Card-FISH en utilisant de sondes d’ARN ribosomique 16S a été effectuée suivant des protocoles existant pour des bactéries et des protistes. Cette technique s’est avérée être un outil précieux pour visualiser des groupes phylogénétiques bactériens en association avec le phytoplancton à l’aide de la microscopie à épifluorescence, sans avoir besoin d'un isolement préalable des cellules ou des interférences avec l'association microbienne. Cependant, la méthode a échoué pour visualiser mixotrophie chez le phytoplancton car la sonde eubactérienne générale(EUB338) combine une large gamme d'espèces phytoplanctoniques, ce qui rend impossible de discriminer les signaux fluorescents provenant de tissus bactérienne ou phytoplanctonique. Le contexte de ces études est le phytoplancton et les bactéries hétérotrophes lesquels constituent des principaux concurrents pour les nutriments inorganiques dissouts. Dans le cas où la croissance bactérienne est limitée par le carbone, l'augmentation de la concentration de carbone organique dissous(DOC) renforce la croissance bactérienne et la consommation de nutriments dissous et ainsi affecte négativement la croissance du phytoplancton autotrophe. Cependant, les consommateurs de bactéries, i.e.phytoflagellés mixotrophes, peuvent être favorisés dans de telles situations car la hausse de DOC donne lieu à l'abondance plus élevé des proies bactériennes.En outre, nos résultats indiquent un potentiel effet positif de la température sur le mode de nutrition hétérotrophe de l’espèce, ainsi qu’une croissante contribution des espèces mixotrophes au sein des communautés de phytoplancton dans des conditions des hautes températures des eaux de surface de la merProtist species were traditionally classified morphologically as either „plants“ or „animals“, based on the absence or presence of chloroplasts. State of science is that a high number of protist species carrychloroplasts but are nutritionally able to employ both autotrophy (photosynthesis) and heterotrophywithin a single cell. This combination of autotrophic and heterotrophic mode of nutrition within a single species is named mixotrophy. In protists, heterotrophy can be realized either by the uptake of food particles (e.g. bacterial prey) through phagocytosis or by the uptake of dissolved organic compounds (i.e.osmotrophy). Mixotrophy is globally and increasingly described in protists from all types of aquatic habitats. Plankton ecologists nowadays assess mixotrophy among the traditionally typified “phyto”plankton and mikro”zoo”plankton species as regularity. Nevertheless, detection and quantification of mixotrophy is still a methodological challenge. In this study, we focused on mixotrophy in marine phytoplankton species and put emphasis on its phagotrophic nutrition from heterotrophic bacterial prey. State of the art methodology was tested to visualize mixotrophy in single phytoplankton cells. Catalyzedreported deposition-fluorescence in situ hybridization (Card-FISH), using 16S ribosomal RNA probes,was employed based on existing protocols for bacteria and protists. The method proved to be a valuable tool to visualise bacterial phylogenetic groups in association with phytoplankton by epifluorescence microscopy without need for prior isolation of cells or interference with the microbial association.However, the method failed to visualize mixotrophy in phytoplankton since the general eubacterial probe(EUB338) hybridised a broad range of phytoplankton species making it impossible to discriminate fluorescent signals originating from bacterial or phytoplankton tissue. Background of these studies is phytoplankton and heterotrophic bacteria being major competitors for dissolved inorganic nutrients. In case that bacterial growth is carbon limited, increasing concentrations of degradable dissolved organic carbon (DOC) enhance bacterial growth and consumption of dissolved nutrients and there by negatively affect autotrophic phytoplankton growth. Bacteria consuming mixotrophic phytoflagellates, however, may gain in importance in such situations since DOC provokes higher bacterial prey supply.In addition, our results indicate a potential positive effect of temperature on O. minima´s heterotrophic nutrition mode, and indicate a potential increasing contribution of mixotrophic species to phytoplankton communities under increasing sea surface water temperatures
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Mitsi, Konstantina 1990. "Eukaryotic diversity through the lens of metabarcoding and metagenomics." Doctoral thesis, TDX (Tesis Doctorals en Xarxa), 2021. http://hdl.handle.net/10803/671809.
Full textAbstract:
Los organismos eucariotas abarcan una diversidad inmensa de formas, tamaños y estilos
de vida. Sin embargo, abordar la verdadera amplitud de esa diversidad es una tarea
laboriosa. Durante las últimas decadas, los estudios de biodiversidad han experimentado un
progreso importante gracias a la incorporación de técnicas basadas en la secuenciación del
ADN. Esta tesis es una composición de tres proyectos independientes donde estas técnicas
se aplican con el objetivo de ampliar nuestro conocimiento de la biodiversidad eucariota. En
el primer proyecto, obtenemos el genoma nuclear y el genoma mitocondrial de un parásito a
partir de un metagenoma eucariota. Definimos la posición filogenética de este nuevo
organismo que se posiciona junto con Filasterea, un grupo de organismos unicelulares que
está estrechamente relacionado con los animales y es clave para estudiar la transición a la
multicelularidad animal. El análisis del contenido génico muestra que el nuevo organismo
posee un genoma reducido en comparación con los otros Filasterea. A pesar de eso, su
genoma codifica un flagelo completo y muchas proteínas que están relacionadas con la
multicelularidad en los animales. En el segundo proyecto, buscamos diversidad molecular
no descrita dentro de los platelmintos, uno de los filos animales más diversos e importantes
desde un punto de vista biomédico. Con este fin, analizamos datos globales de
metabarcoding del gen 18S del ADN ribosomal procedentes de hábitats marinos y de agua
dulce. Nuestros resultados muestran que gran parte de la diversidad molecular de los
platelmintos sigue sin estar documentada e identifican los habitats de agua dulce como
puntos donde buscar nuevas especies de platelmintos. Por último, en el tercer proyecto,
investigamos la novedad a nivel molecular, la composición taxonómica y la estructura de la
comunidad eucariota del lago Sanabria, un lago oligotrófico. Secuenciamos la región
hipervariable V4 del gen 18S del ADN ribosmal y demostramos cómo la elección de los
métodos analíticos (ASVs o OTUs) afectan los resultados y las conclusiones sacadas por un
estudio de biodiversida.. En conjunto, nuestros resultados amplían nuestra perspectiva de la
diversidad eucariota y mejoran nuestra comprensión de la distribución, la ecología, la
novedad molecular y los rasgos genómicos de los eucariotas.Eukaryotes encompass an unprecedented diversity of forms, sizes and lifestyles. However, tackling the real breadth of that diversity is a challenging task. In the last decades, the assessment of biodiversity has seen substantial progress due to the incorporation of culture-independent techniques based on Next Generation DNA Sequencing. This thesis is a composition of three independent projects that implement these techniques aiming to expand our understanding of the extant eukaryotic biodiversity. In the first project, we obtain the nuclear and mitochondrial genomes of Txikispora philomaios, an uncultured unicellular parasite, using a metagenomic approach. We define the phylogenetic position of T.philomaios that branches within Filasterea, a group of unicellular eukaryotes that is closely related to animals and is key to elucidate the transition to animal multicellularity. Despite T.philomaios possessing a reduced genome in comparison to other Filasterea, it has a complete flagellar toolkit and its genome encodes many proteins that are related to multicellularity in animals. In the second project, we seek undescribed molecular diversity inside the phylum Platyhelminthes, one of the most diverse and biomedically important animal phyla. To this end, we analyze global metabarcoding data of the 18S rDNA gene from marine and freshwater habitats. Our results show that a large part of the molecular diversity of Platyhelminthes remains undocumented and identify freshwater environments as potential reservoirs for novel species of flatworms. Finally, in the third project, we investigate the molecular novelty, the taxonomic composition and the structure of the eukaryotic community in Sanabria Lake by sequencing the V4 hypervariable region of the 18S rDNA gene. We show to which extent the choice of the analytical methods (ASVs or OTUs) affects the final results and conclusions of a biodiversity survey. Altogether, our results broaden our perspective of eukaryotic diversity and enhance our understanding of the distribution, the ecology, the molecular novelty and the genomic traits of eukaryotes
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Cai, Ruibo. "Hidden species diversity and the potential for sexual reproduction in the species complex Amoebophrya ceratii (Syndiniales), parasites of marine dinoflagellates." Thesis, Sorbonne université, 2019. http://www.theses.fr/2019SORUS509.
Full textAbstract:
Le parasitisme est un style de vie fréquent dans la nature, et une force évolutive majeure pour les hôtes comme pour les parasites. Les dinoflagellés sont des protistes marins très répandus dans tous les océans, certaines espèces étant même responsables d’efflorescences algales toxiques tandis que d’autres vivent en symbioses mutualistes avec de nombreux coraux. Le complexe d’espèces Amoebophrya ceratii (Syndiniales) inclut de très nombreux parasites de dinoflagellés capables potentiellement de contrôler les efflorescences de ces dinoflagellés. Une très grande diversité a été observée au sein de ce groupe, soit en culture soit dans l’environnement. Ce travail de thèse a pour but d’étudier si la diversité de ces séquences correspond à la diversité au niveau spécifique. Sur la base d’une approche polyphasique faisant intervenir des caractères génétiques et phénotypiques appliqués à 119 individus proches phylogénétiquement, et tous capables d’infecter le même hôte (le dinoflagellé producteur d’efflorescence Scrippsiella trochoidea), j’ai défini 8 ribotypes qui correspondent vraisemblablement à des espèces différentes. Ces résultats prônent l’utilisation de séquences uniques (i.e., divergentes par un seul nucléotide) pour délimiter les espèces dans la région V4 ou V9 du 18S (la petite sous-unité du ribosome) plutôt que de les grouper en unité opérationnelle taxonomique (OTUs). J’ai ensuite recherché l’existence d’une collection de gènes spécifiquement impliqués dans la méiose au sein de deux génomes de référence, et fournit des évidences in silico qu’une reproduction sexuée peut avoir lieu chez ce parasite. J’ai observé que ces gènes étaient surexprimés durant la phase libre du parasite, offrant une piste intéressante pour de prochaines études. En conclusion, ce travail de thèse offre de nouvelles perspectives concernant la diversité largement sous-estimée des Amoebophrya et posent de nouvelles bases pour l’étude de leurs traits biologiquesParasitism is a frequent lifestyle in nature and a major source of evolutionary pressure for both hosts and their parasites. Dinoflagellates are successful marine protists found in oceans worldwide, some of which are responsible for toxic blooms while others live in mutualistic relationships with myriad of corals. Amoebophrya ceratii species complex (Syndiniales) includes a large number of parasites which have the potential for regulating dinoflagellate blooms. A high sequence diversity has been observed for this group in both cultures and environmental investigations. This thesis was aimed to answer whether the sequence diversity represents the species diversity. Based on a polyphasic approach involving genetic and phenotypic characters applied on 119 closely related individuals, all able to infect the same host species (the bloom-forming dinoflagellate Scrippsiella trochoidea), I defined 8 ribotypes which likely correspond to different species. These results advocated for considering unique sequences (i.e., with any nucleotide differences) of 18S-V4 or 18S-V9 (small subunit ribosomal RNA genes) regions for species delimitation rather than grouping them into operational taxonomic units (OTUs). Then I investigated the existence of a set of genes specifically involved in meiosis in two fully sequenced genomes and thereby provided the in silico evidence that sexual reproduction may occur in Amoebophrya. I observed that these genes over-expressed during the free-living stage of the parasite, providing an interesting track to explore. Overall, this thesis offers new insights into the highly underestimated species diversity in Amoebophyra lineage and lays the basis for further study on their biological traits
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Boëchat, Iola Gonçalves. "Biochemical composition of protists." Doctoral thesis, Humboldt-Universität zu Berlin, Landwirtschaftlich-Gärtnerische Fakultät, 2005. http://dx.doi.org/10.18452/15184.
Full textAbstract:
Trotz der Schlüsselstellung heterotropher Protisten als Bindeglied zwischen dem mikrobiellen und dem klassischen Nahrungsnetz ist noch wenig über ihre biochemische Zusammensetzung und ihren Nährwert bekannt. In der vorliegenden Doktorarbeit wurde untersucht ob die biochemische Zusammensetzung von Protisten (1) von deren Nahrungsgrundlage (Alge oder Bakterien) und Ernährungsweise (Autotrophie, Mixotrophie oder Heterotrophie) abhängt und (2) ihre Nahrungsqualität für räuberisches Rotatorien (Keratella quadrata) bedingt. Die Fettsäure-, Sterol- und Aminosäurezusammensetzung vier heterotropher Protisten spiegelte generell die ihrer Nahrung wider. Es trat jedoch eine Akkumulation dieser biochemischen Substanzen in den Protisten auf. Auch die Ernährungsweise eines Flagellaten (Ochromonas sp.) beeinflusste stark dessen biochemische Zusammensetzung, insbesondere die Konzentrationen an mehrfach ungesättigten Fettsäuren (PUFAs). Bei der Untersuchung des Nährwertes vier heterotropher Protisten für K. quadrata wurden signifikante Korrelationen zwischen verschiedenen PUFAs, drei Sterolen und einer Aminosäure (Leucin) der Protisten und der Eiproduktion der Rotatorien festgestellt. Auch die experimentelle Supplementierung eines Flagellaten mit einer PUFA (Docosahexaensäure, DHA) erhöhte seinen Nährwert für die Rotatorien signifikant. Die Ergebnisse verdeutlichen die Fähigkeit heterotropher Protisten, die biochemische Zusammensetzung organischer Materie schon auf einer unteren Ebene des aquatischen Nahrungsnetzes zu verändern, nämlich beim Übergang zwischen Algen/Bakterien und dem Mesozooplankton. Hier können biochemische Änderungen weitreichende Folgen für den Stoff- und Energiefluß des gesamten Nahrungsnetzes nach sich ziehen.Heterotrophic protists are an important link between the microbial and the classical food web. However, little is known about their biochemical composition and nutritional quality as prey. In this thesis, I analysed (1) whether the biochemical composition of the protists depends on their dietary resources (bacterial or algal food) or trophic mode (autotrophy, mixotrophy or heterotrophy), and (2) whether the biochemical composition of protists determines their nutritional quality as prey for a rotifer species (Keratella quadrata). The fatty acid, sterol, and amino acid composition of four heterotrophic protists generally resembled the dietary composition, but the protists accumulated these compounds. Moreover, the trophic mode strongly affected the composition of a flagellate (Ochromonas sp.), especially that of polyunsaturated fatty acids (PUFAs). When investigating the nutritional quality of four protist species for K. quadrata, several PUFAs, three sterols (desmosterol, ergosterol, stigmastanol), and one amino acid (leucine) of the protists were significantly correlated with the rotifer’s egg production. Moreover, the nutritional quality of a heterotrophic flagellate for the rotifer was significantly enhanced by artificially supplementing the flagellate with a PUFA (docosahexaenoic acid, DHA). The thesis highlights the ability of heterotrophic protists to modify the biochemical composition of organic matter at an early stage in aquatic food webs, i.e. at the interface between algae/bacteria and mesozooplankton. Biochemical modifications at this stage may profoundly affect matter and energy transfer through the entire food web.
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Murer, Laurete. "OCORRÊNCIA DE AGENTES PATOGÊNICOS EM FEZES DE BUGIOS-RUIVOS, Alouatta guariba clamitans (PRIMATES), EM UMA ÁREA IMPACTADA PELA FEBRE AMARELA." Universidade Federal de Santa Maria, 2014. http://repositorio.ufsm.br/handle/1/5312.
Full textAbstract:
Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorBrown howler monkeys (Alouatta guariba clamitans) occur in the Brazilian Atlantic Forest from the states of Minas Gerais and Rio de Janeiro to Rio Grande do Sul, and in a small area in northestern Argentina. They are classified as Vulnerable in the state of Rio Grande do Sul due especially to the loss and fragmentation of their natural habitats, and also due to the deaths caused by the recent outbreak of sylvatic yellow fever (2008/2009). The intense human activities on natural habitats, besides the habitat loss, can favor the spread of pathogenic agents such as bacteria and other parasites which affect men and domestic animals, and which can also occur in wildlife animals. This study aimed at verifying the occurrence of Enterobacteriaceae and Cryptosporidium sp. in feces of free-ranging brown howler monkeys in Santa Maria, Rio Grande do Sul, Brazil, and understanding the influence of ecological and environmental factors (group size, howler population density, fragment size, distance to the nearest human settlement, distance to the nearest river and seasonality) on the richness of such organisms. The samples were analyzed at the Center for Studies and Research on Wild Animals (NEPAS / LCDPA) of the Federal University of Santa Maria. Twenty Enterobacteriaceae species were detected, and with the techniques employed, the samples were negative for Salmonella spp. and Cryptosporidium sp. None of the environmental variables had significant influence on the wealth of Enterobacteriaceae. Considering that howler populations at CISM (Campo de Instrução de Santa Maria) fell dramatically due to yellow fever, and that some organisms found in this study may interact with other factors and affect the population dynamics of the howler. We believe that it is fundamental to continue monitoring the health of these populations in order to better understand disease mechanisms, as well as conserve this species.
O bugio-ruivo (Alouatta guariba clamitans) ocorre na Mata Atlântica dos estados de Minas Gerais e Rio de Janeiro ao Rio Grande do Sul e em pequena porção do nordeste da Argentina. É classificado como vulnerável no Rio Grande do Sul devido principalmente à perda e fragmentação de habitat e ao recente surto de febre amarela silvestre (2008/2009). As intensas atividades antrópicas no meio selvagem, além da perda de habitat, podem favorecer a disseminação de agentes patogênicos como bactérias e parasitos, que ocorrem em animais domésticos e em humanos e que podem acometer também os animais selvagens. O objetivo deste estudo foi verificar a ocorrência de bactérias da família Enterobacteriaceae e do protista Cryptosporidium sp. em fezes de bugios-ruivos de vida livre no município de Santa Maria, Rio Grande do Sul, Brasil, bem como relacionar a riqueza de enterobactérias nas amostras com fatores ecológicos e ambientais como tamanho do grupo, tamanho do fragmento florestal, densidade de populações de bugios, distância com núcleos humanos mais próximos, distância para cursos d água e sazonalidade. As amostras foram analisadas no Núcleo de Estudos e Pesquisas em Animais Silvestres (NEPAS/LCDPA) da Universidade Federal de Santa Maria. Foram detectadas vinte espécies de enterobactérias, e com as técnicas empregadas, as amostras foram negativas para Salmonella spp. e Cryptosporidium sp.. Nenhuma das variáveis ambientais analisadas teve influência sobre a riqueza das enterobactérias. Considerando que as populações de bugios do Campo de Instrução de Santa Maria (CISM) sofreram uma drástica redução devida à febre amarela, e que alguns organismos encontrados nesse estudo podem estar interagindo com outros fatores e assim afetar a dinâmica populacional dos bugios. Acredita-se que a continuidade do monitoramento da saúde destas populações seja fundamental para melhorar a compreensão dos mecanismos das doenças, assim como para a conservação dessa espécie.
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Scoble, Josephine Margaret. "Diversity of silica-scaled protists." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:7bc73ed7-418b-49de-963b-81407a7c3a49.
Full textAbstract:
This thesis investigates the diversity of two silica-scaled protist groups, Paraphysomonadida and Thaumatomonadida by light and electron microscopical observations and sequencing (rDNA) on novel clonal cultures. Despite these groups of protist dominating pelagic, littoral as well as inland freshwater and soil habitats, they are taxonomically poorly understood to the extent that any progress in ecological theory is hampered. Now that environmental DNA sequencing is being carried out faster than we can characterise protists from culture it is important that we understand how molecular and physical diversity match up, especially because so many protists are morphospecies. Nearly one hundred isolates were cultured on which both morphological and molecular data was carried out in parallel to reveal around 50 new species of protist from eight different genera: two heterokont genera, Paraphysomonas and Incisomonas n. gen., and six cercozoan genera, Thaumatomonas, Allas, Reckertia, Thaumatospina n. gen., Cowlomonas n. gen., and Scutellomonas n. gen. These data make major contributions to taxonomy and understanding aspects of protist diversity where previously morphological diversity was heavily biased towards over- generalized morphotypes. This thesis quickly showed that gross lumping of morphospecies was true of Paraphysomonas, for which many of the isolates cultured herein might have been regarded as one species (not more than 20). The many cultured isolates exhibited varied cell and scale morphology, and by sequencing (rDNA), it was possible to see the evolution of scale morphology map on to trees. This marriage of molecular and morphological data made it possible to view distinct groups of species that shared scale detail that might have otherwise been overlooked had either method been used alone. This research has shed significant light on how scale morphology can be used as reliable taxonomic marker for protists, the insights of which can be applied to make taxonomic improvements to other silica-scaled protist groups.
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Dias, Roberto Júnio Pedroso. "Protistas Ciliados (Protista, Ciliophora) encontrados no Córrego São Pedro (Bacia do Rio Paraibuna), município de Juiz de Fora, Minas Gerais: taxonomia, morfologia, biomonitoramento e relações epibióticas." Universidade Federal de Juiz de Fora (UFJF), 2007. https://repositorio.ufjf.br/jspui/handle/ufjf/4459.
Full textAbstract:
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No presente trabalho, foram estudados os aspectos da taxonomia e morfologia dos protistas ciliados encontrados no córrego São Pedro (Juiz de Fora, MG), bem como o potencial destes microorganismos como indicadores da qualidade da água e ainda os aspectos ecológicos das relações epibióticas entre os ciliados e alguns macroinvertabrados bentônicos. A presente dissertação está dividida em sete capítulos. No capítulo 1, foi realizado o inventário dos ciliados encontrados em cinco estações amostrais do córrego, durante um ano de estudo, e foi observada a sucessão destes protistas em laboratório. Foram identificadas 42 espécies de ciliados e caracterizou-se morfologicamente Apoamphisiella sp. nov. (Spirotrichea, Amphisiellidae). No capítulo 2, foi descrito um doublet do tipo imagem espelhada em Gastrostyla setifera (Spirotrichea, Oxytrichidae), obtida de amostras de água e sedimento de uma estação amostral do córrego São Pedro. O capítulo 3 registra a presença de Neobursaridium gigas (Oligohymenophorea, Neobursaridiidae) no córrego e apresenta uma revisão dos aspectos morfológicos, ecológicos e da distribuição geográfica deste ciliado. No capítulo 4, verificou-se a influência da poluição orgânica sobre a composição e a distribuição da taxocenose de protistas ciliados ao longo do córrego, com o objetivo de avaliar a qualidade da água deste sistema lótico. Durante o estudo de um ano, em cinco estações amostrais ao longo do córrego, foram encontradas 39 espécies de protistas ciliados, das quais 32 estão incluídas no sistema sapróbio e são consideradas bioindicadoras. A composição e a distribuição da taxocenose de protistas ciliados variaram espacial e temporalmente. O índice sapróbio e o índice de valência sapróbia foram utilizados para avaliar a qualidade da água das cinco estações amostrais e demonstraram o alto grau de poluição das estações 4 e 5. Os dados obtidos confirmam que, em águas correntes, a poluição orgânica parece ser um fator determinante, capaz de influenciar a composição, a distribuição e a estrutura trófica da taxocenose de protozoários ciliados. Os capítulos seguintes versam sobre as associações epibióticas dos protistas ciliados com moluscos, oligoquetas e larvas de insetos. No capítulo 5, foram registradas sete espécies de ciliados sobre as conchas de Pomacea figulina, sendo seis pertencentes à subclasse Peritrichia: Carchesium polypinum, Vorticella microstoma, Vorticella campanula, Epistylis plicatilis, Epistylis sp., Opercullaria sp. e uma pertencente à subclasse Suctoria: Hypophrya fasciculata. Os resultados são discutidos em termos das vantagens e desvantagens desta relação para os protistas ciliados e dos aspectos ecológicos envolvidos nesta associação. No capítulo 6, foram investigados o sítio de localização e o padrão de distribuição espacial e temporal de protistas ciliados peritríquios do gênero Rhabdostyla colonizando oligoquetas límnicos tubificídeos da espécie Limnodrilus hoffmeisteri (Oligochaeta, Tubificidae) nas cinco estações amostrais do córrego, ao longo de 11 meses de coleta. O padrão de ocorrência dos epibiontes sobre os oligoquetas apresentou heterogeneidade espacial e temporal. Os resultados são discutidos em termos das possíveis causas da localização dos ciliados preferencialmente na região posterior dos oligoquetas e dos fatores relacionados ao padrão de distribuição espacial e temporal heterogêneo. E finalmente, o capítulo 7 relata a ocorrência de Rhabdostyla chironomi (Ciliophora, Peritrichia) sobre larvas de Chironomus decorus (Diptera, Chironomidae) no córrego e reporta, ainda, os fatores envolvidos na localização dos ciliados sobre os túbulos abdominais dos hospedeiros e a possível utilização desta relação como indicadora da qualidade da água.
In the present study, both taxonomy and morphology aspects of the ciliate protists found in São Pedro stream (Juiz de Fora-MG), as well as their potential as water quality indicators were studied together with the ecological aspects of the epibiotic relation between the ciliate and some benthic macroinvertebrates. The present dissertation is divided into seven chapters. In chapter 1, the survey of ciliate protists was obtained from samples of water and sediment from the stream, during a hole year, and the succession of these protists was observed in laboratory. Forty-two ciliate species were identified and Apoamphisiella sp. n. (Spirotrichea, Amphisiellidae) was morfologically characterized. In chapter 2, mirror-image doublet was described in Gastrostyla setifera (Spirotrichea, Oxytrichidae), obtained from samples of water and sediment at the São Pedro stream. The Chapter 3 registers the presence of Neobursaridium gigas Balech, 1941 (Oligohymenophorea, Neobursaridiidae) in the stream and presents a revision of the morphological aspects of this ciliate, as well as its ecological and geographical distribution. In chapter 4, the influence of the organic pollution on both the composition and the distribution of the taxocenose of ciliate protists along the stream had the aim of evaluating the water quality of this lotic system. During the one year study, 39 ciliate protist species were found, 32 of which were included in the saprobic system and their potencial as indicators are considered. The composition and the distribution of the taxocenose of ciliate protist varied both spatial and seasonally. The saprobic index and the valency methods were used to evaluate the water quality at the five stations and they demonstrated the high degree of pollution on stations 4 and 5. Our results confirm that the organic load in watercourses may be a dominating factor capable of influencing the composition, distribution and trophic structure of the taxocenose of ciliate protist. The following chapters consider the epibiotic ciliate protist associations to mollusks, oligochates and insect larvae. In chapter 5, seven ciliate species were registered on the shells of Pomacea figulina, six of which belonging to the subclass Peritrichia: Carchesium polypinum, Vorticella microstoma, Vorticella campanula, Epistylis plicatilis, Epistylis sp., Opercullaria sp. and one belonging to the subclass Suctoria: Hypophrya fasciculata. Results are discussed in terms of the advantages and disadvantages of this relationship from the ciliate protist point of view, together with the ecological aspects involved in this association. In chapter 6, location ranch and both spatial and temporal distribution patterns of Rhabdostyla peritrichids were found colonizing limnic oligochaetes Tubificidae of the species Limnodrilus hoffmeisteri in the five amostral stations, during 11 months of collection. The occurrence pattern of the epibionts on the oligochaetes was spatial and seasonally heterogeneous. Results are discussed in terms of the possible causes for the site preference of the ciliates in the posterior region of the oligochaetes and factors related to the heterogeneous pattern of space and temporal distribution. Finally, chapter 7 registers the occurrence of Rhabdostyla chironomi (Ciliophora, Peritrichia) on Chironomus decorus larvae (Diptera, Chironomidae) in the stream and still it moderates the factors involved in the location of the ciliates on the ventral tubules of its hosts and the possible usage of this relationship as indicative of the water quality.
Books on the topic "Protiste"
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Arato, Rona. Protists: Algae, amoebas, plankton, and other protists. New York: Crabtree Pub. Co., 2010.
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Silverstein, Alvin. Monerans & protists. New York: Twenty-First Century Books, 1996.
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Ohtsuka, Susumu, Toshinobu Suzaki, Takeo Horiguchi, Noritoshi Suzuki, and Fabrice Not, eds. Marine Protists. Tokyo: Springer Japan, 2015. http://dx.doi.org/10.1007/978-4-431-55130-0.
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Arato, Rona. Protists: Algae, amoebas, plankton, and other protists. New York, N.Y: Crabtree Pub. Co., 2010.
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Rogers, Kara. Fungi, algae, and protists. New York, NY: Britannica Educational Pub. in association with Rosen Educational Services, 2011.
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Steve, Parker. Protozoans, algae & other protists. Minneapolis, Minn: Compass Point Books, 2009.
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Archibald, John M., Alastair G. B. Simpson, Claudio H. Slamovits, Lynn Margulis, Michael Melkonian, David J. Chapman, and John O. Corliss, eds. Handbook of the Protists. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-32669-6.
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Rogers, Kara. Fungi, algae, and protists. New York, NY: Britannica Educational Pub. in association with Rosen Educational Services, 2011.
Find full textBook chapters on the topic "Protiste"
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Bruno, David W., Patricia A. Noguera, and Trygve T. Poppe. "Protists." In A Colour Atlas of Salmonid Diseases, 107–21. Dordrecht: Springer Netherlands, 2013. http://dx.doi.org/10.1007/978-94-007-2010-7_8.
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Gooch, Jan W. "Protista." In Encyclopedic Dictionary of Polymers, 918. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-6247-8_14594.
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Amils, Ricardo. "Protists." In Encyclopedia of Astrobiology, 1. Berlin, Heidelberg: Springer Berlin Heidelberg, 2014. http://dx.doi.org/10.1007/978-3-642-27833-4_1900-2.
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Amils, Ricardo. "Protists." In Encyclopedia of Astrobiology, 2039. Berlin, Heidelberg: Springer Berlin Heidelberg, 2015. http://dx.doi.org/10.1007/978-3-662-44185-5_1900.
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Amils, Ricardo. "Protists." In Encyclopedia of Astrobiology, 1351–52. Berlin, Heidelberg: Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-11274-4_1900.
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Gómez-Gutiérrez, Jaime, So Kawaguchi, and José Raúl Morales-Ávila. "Protista." In Global Diversity and Ecological Function of Parasites of Euphausiids, 59–131. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-41055-5_6.
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Gooch, Jan W. "Protist." In Encyclopedic Dictionary of Polymers, 918. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-6247-8_14595.
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Evert, Ray F., and Susan E. Eichhorn. "Protists: Algae and Heterotrophic Protists." In Raven Biology of Plants, 317–65. New York: Macmillan Learning, 2013. http://dx.doi.org/10.1007/978-1-319-15626-8_16.
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Stanier, Roger Y., John L. Ingraham, Mark L. Wheelis, and Page R. Painter. "The Protists." In General Microbiology, 525–44. London: Macmillan Education UK, 1986. http://dx.doi.org/10.1007/978-1-349-08754-9_26.
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Stanier, Roger Y., John L. Ingraham, Mark L. Wheelis, and Page R. Painter. "The Protists." In General Microbiology, 525–44. London: Macmillan Education UK, 1986. http://dx.doi.org/10.1007/978-1-349-15028-1_26.
Full textConference papers on the topic "Protiste"
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Cohen, Phoebe, and Leigh Anne Riedman. "IT’S A PROTIST-EAT-PROTIST WORLD: RECALCITRANCE, PREDATION, AND EVOLUTION IN THE TONIAN–CRYOGENIAN OCEAN." In GSA Annual Meeting in Indianapolis, Indiana, USA - 2018. Geological Society of America, 2018. http://dx.doi.org/10.1130/abs/2018am-318646.
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Lipps, Jere H., Yoshi Ishitani, Yurika Ujiie, and Michele Weber. "ORIGIN OF SKELETONIZED PROTISTS AND METAZOANS: GENOMIC AND FOSSIL EVIDENCE." In GSA Annual Meeting in Indianapolis, Indiana, USA - 2018. Geological Society of America, 2018. http://dx.doi.org/10.1130/abs/2018am-319008.
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Nettersheim, B. J., J. J. Brocks, I. Bobrovskiy, and C. Hallmann. "Reconsidering the Role of Animals and Protists During the Neoproterozoic-Cambrian Transition." In 29th International Meeting on Organic Geochemistry. European Association of Geoscientists & Engineers, 2019. http://dx.doi.org/10.3997/2214-4609.201903048.
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Burke, Janet, Leanne E. Elder, Amy E. Maas, Daniel E. Gaskell, Elizabeth G. Clark, Allison Y. Hsiang, Gavin L. Foster, and Pincelli Hull. "CAN LOW ALLOMETRIC SCALING OF RESPIRATION RATES EXPLAIN GIGANTISM IN PELAGIC PROTISTS?" In GSA 2020 Connects Online. Geological Society of America, 2020. http://dx.doi.org/10.1130/abs/2020am-358799.
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Toti, Kiran, Jan Balzarini, and Serge Van Calenbergh. "Dideoxyapiose nucleosides revisited: syntheses and protide derivatives." In XVth Symposium on Chemistry of Nucleic Acid Components. Prague: Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, 2011. http://dx.doi.org/10.1135/css201112480.
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Caron, D. A., P. D. Countway, A. Schnetzer, and M. Travao. "Protistan biodiversity in the plankton: new insights from new approaches." In Oceans 2003. Celebrating the Past ... Teaming Toward the Future (IEEE Cat. No.03CH37492). IEEE, 2003. http://dx.doi.org/10.1109/oceans.2003.178251.
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Bos, Mark, Olger Koop, and Ernst Bolt. "Safety Level of a Probabilistic Admittance Policy." In ASME 2011 30th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2011. http://dx.doi.org/10.1115/omae2011-49357.
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The main factor restricting admission of deep-draught ships to ports is the risk of bottom contact. In the approach channels to Rotterdam and IJmuiden such ships are subject to tidal windows because of the limited depths in the approach channels. Some decades ago probabilistic methods were introduced for the allocation of tidal windows for the Euro-Maas channel to Rotterdam and later also for the IJ channel to IJmuiden. These methods are being further developed. The increased accuracy of computational methods and of forecasted wave conditions and water levels may lead to an increased accessibility of the port. Recent developments have resulted in the new tidal window advice program Protide (PRObabilistic TIdal window DEtermination). The objective of the work presented in this paper is the verification and validation of Protide for the Euro-Maas channel to Rotterdam and for the IJ channel to IJmuiden. The probability of bottom contact during channel transit is simulated for time series of ten years of measured wave data and water levels. The fleet of ships is represented by a limited number of ships and for each ship all possible tidal windows for the ten year period are determined with Protide. A database is developed with motion response characteristics for each of the representative ships. For all possible arrival times in the ten-year period, indicated as safe by Protide, a channel transit is simulated. The probability of bottom contact during the simulated transit is computed from the motion response characteristics of the ship and with the measured wave spectra and the measured water level. Two safety criteria are applied. Firstly the probability of bottom contact during a single channel transit should not be excessive. Secondly the total probability of bottom contact during a long period of application of the admittance policy should be limited. To determine the probability that a certain ship is in a certain section of the channel some elements from queuing theory are applied. The probability that the ship is present in each channel section combined with the probability of bottom contact results in the probability of bottom contact for the ship in the channel. This leads to a long term probability of bottom contact for the channel. This paper presents the analysis method and selected simulation results for Euro-Maas channel in detail.
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Wulandari, E., and Azwir Anhar. "The Validity of Interactive Learning Multimedia on Protista and Fungi Materials for Senior High School." In International Conference on Biology, Sciences and Education (ICoBioSE 2019). Paris, France: Atlantis Press, 2020. http://dx.doi.org/10.2991/absr.k.200807.019.
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Hardyanto, Yanang Surya Putra, Murni Sapta Sari, Triastono Imam Prasetyo, and Sulisetijono. "Formative assessment instruments based on discovery learning for measuring cognitive and psychomotor learning outcomes of students in protista material." In THE 4TH INTERNATIONAL CONFERENCE ON MATHEMATICS AND SCIENCE EDUCATION (ICoMSE) 2020: Innovative Research in Science and Mathematics Education in The Disruptive Era. AIP Publishing, 2021. http://dx.doi.org/10.1063/5.0043492.
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Blagden, Sarah P., Fiona G. McKissock, Janet S. Graham, Kristen K. Ciombor, Francesca Aroldi, Lisa J. Rodgers, Michelle Myers, Jordan Berlin, T. R. Jeffry Evans, and David J. Harrison. "Abstract C059: Inhibition of thymidylate synthase by the ProTide NUC-3373:in vitroanalysis and clinical validation." In Abstracts: AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics; October 26-30, 2019; Boston, MA. American Association for Cancer Research, 2019. http://dx.doi.org/10.1158/1535-7163.targ-19-c059.
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