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Mitchell, Edward

Nom
Mitchell, Edward
Affiliation principale
Site web
Fonction
Professeur ordinaire
Email
edward.mitchell@unine.ch
Identifiants
https://libra.unine.ch/handle/123456789/357
_
0000-0003-0358-506X

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  • Publication
    Accès libre
    Comparing Potential COI and SSU rDNA Barcodes for Assessing the Diversity and Phylogenetic Relationships of Cyphoderiid Testate Amoebae (Rhizaria: Euglyphida)
    (2011)
    Heger, Thierry J.
    ;
    Pawlowski, Jan
    ;
    Lara, Enrique 
    ;
    Leander, Brian S.
    ;
    Todorov, Milcho
    ;
    Golemansky, Vassil
    ;
    Mitchell, Edward 
    The mitochondrial Cytochrome Oxidase Subunit 1 gene (COI) has been promoted as an ideal “DNA barcode” for animal species and other groups of eukaryotes. However, the utility of the COI marker for species level discrimination and for phylogenetic analyses has yet to be tested within the Rhizaria. Accordingly, we analysed mitochondrial COI gene sequences and nuclear small subunit rDNA (SSU) sequences from several morphospecies of euglyphid testate amoebae (Cercozoa, Rhizaria) in order to evaluate the utility of these DNA markers for species discrimination and phylogenetic reconstructions. Sequences were obtained from eleven populations belonging to six Cyphoderia morphospecies that were isolated from field samples in North America and Europe. Mean inter-population COI sequence dissimilarities were on average 2.9 times greater than in the SSU, while the intra-population sequence dissimilarities were higher in the SSU (0-0.95%) than in the COI (0%); this suggests that the COI fragment is valuable for discriminating Cyphoderiidae isolates. Our study also demonstrated that COI sequences are useful for inferring phylogenetic relationships among Cyphoderiidae isolates. COI and SSU tree topologies were very similar even though the COI fragment used in these analyses (500 bp) was much shorter than the SSU sequences (1600 bp). Altogether, these results demonstrate the utility of the COI as a potential taxonomic DNA barcode for assessing cyphoderiid species diversity and for inferring phylogenetic relationships within the group.
  • Publication
    Métadonnées seulement
    The testate lobose amoebae (order Arcellinida Kent, 1880) finally find their home within Amoebozoa
    (2005)
    Nikolaev, Sergey I
    ;
    Mitchell, Edward 
    ;
    Petrov, Nikolay B
    ;
    Berney, Cédric
    ;
    Fahrni, José
    ;
    Pawlowski, Jan
    Testate lobose amoebae (order Arcellinida Kent, 1880) are common in all aquatic and terrestrial habitats, yet they are one of the last higher taxa of unicellular eukaryotes that has not found its place in the tree of life. The morphological approach did not allow to ascertain the evolutionary origin of the group or to prove its monophyly. To solve these challenging problems, we analyzed partial small-subunit ribosomal RNA (SSU rRNA) genes of seven testate lobose amoebae from two out of the three suborders and seven out of the 13 families belonging to the Arcellinida. Our data support the monophyly of the order and clearly establish its position among Amoebozoa, as a sister-group to the clade comprising families Amoebidae and Hartmannellidae. Complete SSU rRNA gene sequences from two species and a partial actin sequence from one species confirm this position. Our phylogenetic analyses including representatives of all sequenced lineages of lobose amoebae suggest that a rigid test appeared only once during the evolution of the Amoebozoa, and allow reinterpretation of some morphological characters used in the systematics of Arcellinida. (c) 2005 Published by Elsevier GmbH.
  • Publication
    Accès libre
    The Testate Lobose Amoebae (Order Arcellinida Kent, 1880) Finally Find their Home within Amoebozoa
    (2005)
    Nikolaev, Sergey I.
    ;
    Mitchell, Edward 
    ;
    Petrov, Nikolay B.
    ;
    Berney, Cédric
    ;
    Fahrni, José
    ;
    Pawlowski, Jan
    Testate lobose amoebae (order Arcellinida Kent, 1880) are common in all aquatic and terrestrial habitats, yet they are one of the last higher taxa of unicellular eukaryotes that has not found its place in the tree of life. The morphological approach did not allow to ascertain the evolutionary origin of the group or to prove its monophyly. To solve these challenging problems, we analyzed partial small-subunit ribosomal RNA (SSU rRNA) genes of seven testate lobose amoebae from two out of the three suborders and seven out of the 13 families belonging to the Arcellinida. Our data support the monophyly of the order and clearly establish its position among Amoebozoa, as a sister-group to the clade comprising families Amoebidae and Hartmannellidae. Complete SSU rRNA gene sequences from two species and a partial actin sequence from one species confirm this position. Our phylogenetic analyses including representatives of all sequenced lineages of lobose amoebae suggest that a rigid test appeared only once during the evolution of the Amoebozoa, and allow reinterpretation of some morphological characters used in the systematics of Arcellinida.