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  • 1
    Online Resource
    Online Resource
    The twilight of Heliozoa and rise of Rhizaria, an emerging supergroup of amoeboid eukaryotes
    Proceedings of the National Academy of Sciences ; 2004
    In:  Proceedings of the National Academy of Sciences Vol. 101, No. 21 ( 2004-05-25), p. 8066-8071
    Details
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 101, No. 21 ( 2004-05-25), p. 8066-8071
    Abstract: Recent molecular phylogenetic studies revealed the extraordinary diversity of single-celled eukaryotes. However, the proper assessment of this diversity and accurate reconstruction of the eukaryote phylogeny are still impeded by the lack of molecular data for some major groups of easily identifiable and cultivable protists. Among them, amoeboid eukaryotes have been notably absent from molecular phylogenies, despite their diversity, complexity, and abundance. To partly fill this phylogenetic gap, we present here combined small-subunit ribosomal RNA and actin sequence data for the three main groups of “Heliozoa” (Actinophryida, Centrohelida, and Desmothoracida), the heliozoan-like Sticholonche , and the radiolarian group Polycystinea. Phylogenetic analyses of our sequences demonstrate the polyphyly of heliozoans, which branch either as an independent eukaryotic lineage (Centrohelida), within stramenopiles (Actinophryida), or among cercozoans (Desmothoracida), in broad agreement with previous ultrastructure-based studies. Our data also provide solid evidence for the existence of the Rhizaria, an emerging supergroup of mainly amoeboid eukaryotes that includes desmothoracid heliozoans, all radiolarians, Sticholonche , and foraminiferans, as well as various filose and reticulose amoebae and some flagellates.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    URL: Article
    DOI: 10.1073/pnas.0308602101
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2004
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
    Location Call Number Limitation Availability
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  • 2
    Online Resource
    Online Resource
    Evolution of Antp-class genes and differential expression of Hydra Hox/paraHox genes in anterior patterning
    Proceedings of the National Academy of Sciences ; 2000
    In:  Proceedings of the National Academy of Sciences Vol. 97, No. 9 ( 2000-04-25), p. 4493-4498
    Details
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 97, No. 9 ( 2000-04-25), p. 4493-4498
    Abstract: The conservation of developmental functions exerted by Antp-class homeoproteins in protostomes and deuterostomes suggested that homologs with related functions are present in diploblastic animals. Our phylogenetic analyses showed that Antp-class homeodomains belong either to non-Hox or to Hox/paraHox families. Among the 13 non-Hox families, 9 have diploblastic homologs, Msx , Emx , Barx , Evx , Tlx , NK-2 , and Prh/Hex , Not , and Dlx , reported here. Among the Hox/paraHox, poriferan sequences were not found, and the cnidarian sequences formed at least five distinct cnox families. Two are significantly related to the paraHox Gsx (cnox-2) and the mox (cnox-5) sequences, whereas three display some relatedness to the Hox paralog groups 1 (cnox-1), 9/10 (cnox-3) and the paraHox cdx (cnox-4). Intermediate Hox/paraHox genes (PG 3 to 8 and lox ) did not have clear cnidarian counterparts. In Hydra , cnox-1 , cnox-2 , and cnox-3 were not found chromosomally linked within a 150-kb range and displayed specific expression patterns in the adult head. During regeneration, cnox-1 was expressed as an early gene whatever the polarity, whereas cnox-2 was up-regulated later during head but not foot regeneration. Finally, cnox-3 expression was reestablished in the adult head once it was fully formed. These results suggest that the Hydra genes related to anterior Hox/paraHox genes are involved at different stages of apical differentiation. However, the positional information defining the oral/aboral axis in Hydra cannot be correlated strictly to that characterizing the anterior–posterior axis in vertebrates or arthropods.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    URL: Article
    DOI: 10.1073/pnas.97.9.4493
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2000
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
    Location Call Number Limitation Availability
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    Online Resource
  • 3
    Online Resource
    Online Resource
    The evolution of early Foraminifera
    Proceedings of the National Academy of Sciences ; 2003
    In:  Proceedings of the National Academy of Sciences Vol. 100, No. 20 ( 2003-09-30), p. 11494-11498
    Details
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 100, No. 20 ( 2003-09-30), p. 11494-11498
    Abstract: Fossil Foraminifera appear in the Early Cambrian, at about the same time as the first skeletonized metazoans. However, due to the inadequate preservation of early unilocular (single-chambered) foraminiferal tests and difficulties in their identification, the evolution of early foraminifers is poorly understood. By using molecular data from a wide range of extant naked and testate unilocular species, we demonstrate that a large radiation of nonfossilized unilocular Foraminifera preceded the diversification of multilocular lineages during the Carboniferous. Within this radiation, similar test morphologies and wall types developed several times independently. Our findings indicate that the early Foraminifera were an important component of Neoproterozoic protistan community, whose ecological complexity was probably much higher than has been generally accepted.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    URL: Article
    DOI: 10.1073/pnas.2035132100
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2003
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
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