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Mitchell, Edward
Nom
Mitchell, Edward
Affiliation principale
Fonction
Professeur ordinaire
Email
edward.mitchell@unine.ch
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Résultat de la recherche
Voici les éléments 1 - 10 sur 44
- PublicationAccès libreAssessing the responses of Sphagnum micro-eukaryotes to climate changes using high throughput sequencing(2020-9-18)
; ; ; - PublicationMétadonnées seulementResponse of forest soil euglyphid testate amoebae (Rhizaria: Cercozoa) to pig cadavers assessed by high-throughput sequencing(2016-3-1)
; ; ; ; ; Decomposing cadavers modify the soil environment, but the effect on soil organisms and especially on soil protists is still poorly documented. We conducted a 35-month experiment in a deciduous forest where soil samples were taken under pig cadavers, control plots and fake pigs (bags of similar volume as the pigs). We extracted total soil DNA, amplified the SSU ribosomal RNA (rRNA) gene V9 region and sequenced it by Illumina technology and analysed the data for euglyphid testate amoebae (Rhizaria: Euglyphida), a common group of protozoa known to respond to micro- environmental changes. We found 51 euglyphid operational taxonomic units (OTUs), 45 of which did not match any known sequence. Most OTUs decreased in abundance underneath cadavers between days 0 and 309, but some responded positively after a time lag. We sequenced the full-length SSU rRNA gene of two common OTUs that responded positively to cadavers; a phylogenetic analysis showed that they did not belong to any known euglyphid family. This study confirmed the existence of an unknown diversity of euglyphids and that they react to cadavers. Results suggest that metabarcoding of soil euglyphids could be used as a forensic tool to estimate the post-mortem interval (PMI) particularly for long-term (>2 months) PMI, for which no reliable tool exists. - PublicationMétadonnées seulementEcology of testate amoebae in peatlands of central China and development of a transfer function for paleohydrological reconstruction(2013)
; ; ; - PublicationMétadonnées seulementUsing DNA-barcoding for sorting out protist species complexes: A case study of the Nebela tincta-collaris-bohemica group (Amoebozoa; Arcellinida, Hyalospheniidae)(2013)
; ; - PublicationMétadonnées seulementRelationships between testate amoeba communities and water quality in Lake Donghu, a large alkaline lake in Wuhan, China(2013)
; ; ; - PublicationMétadonnées seulementThe Revised Classification of Eukaryotes (vol 59, pg 429, 2012)(2013)
; ; - PublicationMétadonnées seulementAmphitremida (Poche, 1913) Is a New Major, Ubiquitous Labyrinthulomycete Clade(2013)
; Micro-eukaryotic diversity is poorly documented at all taxonomic levels and the phylogenetic affiliation of many taxa - including many well-known and common organisms - remains unknown. Among these incertae sedis taxa are Archerella flavum (Loeblich and Tappan, 1961) and Amphitrema wrightianum (Archer, 1869) (Amphitremidae), two filose testate amoebae commonly found in Sphagnum peatlands. To clarify their phylogenetic position, we amplified and sequenced the SSU rRNA gene obtained from four independent DNA extractions of A. flavum and three independent DNA extractions of A. wrightianum. Our molecular data demonstrate that genera Archerella and Amphitrema form a fully supported deep-branching clade within the Labyrinthulomycetes (Stramenopiles), together with Diplophrys sp. (ATCC50360) and several environmental clones obtained from a wide range of environments. This newly described clade we named Amphitremida is diverse genetically, ecologically and physiologically. Our phylogenetic analysis suggests that osmotrophic species evolved most likely from phagotrophic ancestors and that the bothrosome, an organelle that produces cytoplasmic networks used for attachment to the substratum and to absorb nutrients from the environments, appeared lately in labyrithulomycete evolution. - PublicationAccès librerRNA Phylogeny of Arcellinida (Amoebozoa) Reveals that the Largest Arcellinid Genus, Difflugia Leclerc 1815, is not Monophyletic(2012)
; The systematics of lobose testate amoebae (Arcellinida), a diverse group of shelled free-living unicellular eukaryotes, is still mostly based on morphological criteria such as shell shape and composition. Few molecular phylogenetic studies have been performed on these organisms to date, and their phylogeny suffers from typical under-sampling artefacts, resulting in a still mostly unresolved tree. In order to clarify the phylogenetic relationships among arcellinid testate amoebae at the inter-generic and inter-specific level, and to evaluate the validity of the criteria used for taxonomy, we amplified and sequenced the SSU rRNA gene of nine taxa - Difflugia bacillariarum, D. hiraethogii, D. acuminata, D. lanceolata, D. achlora, Bullinularia gracilis, Netzelia oviformis, Physochila griseola and Cryptodifflugia oviformis. Our results, combined with existing data demonstrate the following: 1) Most arcellinids are divided into two major clades, 2) the genus Difflugia is not monophyletic, and the genera Netzelia and Arcella are closely related, and 3) Cryptodifflugia branches at the base of the Arcellinida clade. These results contradict the traditional taxonomy based on shell composition, and emphasize the importance of general shell shape in the taxonomy of arcellinid testate amoebae. - PublicationMétadonnées seulementTime to regulate microbial eukaryote nomenclature(2012)
; Nomenclature of microbial eukaryotes has been historically relegated to secondary importance. This is a legacy of the traditional classification of life into the most studied multicellular forms (plants, fungi, and animals). Despite the revolution in an understanding of eukaryotic diversity and relationships that has been achieved as a result of the use of molecular techniques, the description of microbial eukaryote genera and species is more difficult today than in the past. Researchers are at liberty to choose between the botanical (in the traditional sense) and zoological codes of nomenclature, although there is no obligation to comply with either. We demonstrate that, by combining the foci of different nomenclature codes with the current knowledge of relationships, a large number of genera and species end up being regulated by two codes (Patterson's ambiregnal taxa) and, in some cases, may even be regulated by none. We briefly present historically proposed types of solutions to this problem, and propose that an elaboration of authoritative guidelines to regulate the nomenclature of microbial eukaryotes by the community of researchers is most appropriate at this time. Most importantly, we plead to the community of researchers to resolve this centuries old outstanding issue. (C) 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, , . - PublicationMétadonnées seulementThe Revised Classification of Eukaryotes(2012)
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