Vd'acny Peter

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Vd'acny
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  • Article
    Genealogical analyses of multiple loci of litostomatean ciliates (Protista, Ciliophora, Litostomatea)
    (Elsevier, 2012-07-09) Vd'acny, Peter ; Bourland, William A. ; Orsi, William D. ; Epstein, Slava S. ; Foissner, Wilhelm
    The class Litostomatea is a highly diverse ciliate taxon comprising hundreds of free-living and endocommensal species. However, their traditional morphology-based classification conflicts with 18S rRNA gene phylogenies indicating (1) a deep bifurcation of the Litostomatea into Rhynchostomatia and Haptoria + Trichostomatia, and (2) body polarization and simplification of the oral apparatus as main evolutionary trends in the Litostomatea. To test whether 18S rRNA molecules provide a suitable proxy for litostomatean evolutionary history, we used eighteen new ITS1-5.8S rRNA-ITS2 region sequences from various free-living litostomatean orders. These single- and multiple-locus analyses are in agreement with previous 18S rRNA gene phylogenies, supporting that both 18S rRNA gene and ITS region sequences are effective tools for resolving phylogenetic relationships among the litostomateans. Despite insertions, deletions and mutational saturations in the ITS region, the present study shows that ITS1 and ITS2 molecules can be used to infer phylogenetic relationships not only at species level but also at higher taxonomic ranks when their secondary structure information is utilized to aid alignment.
  • Article
    Prevalence of partnerships between bacteria and ciliates in oxygen-depleted marine water columns
    (Frontiers Media, 2012-09-19) Orsi, William D. ; Charvet, Sophie ; Vd'acny, Peter ; Bernhard, Joan M. ; Edgcomb, Virginia P.
    Symbioses between Bacteria, Archaea, and Eukarya in deep-sea marine environments represent a means for eukaryotes to exploit otherwise inhospitable habitats. Such symbioses are abundant in many low-oxygen benthic marine environments, where the majority of microbial eukaryotes contain prokaryotic symbionts. Here, we present evidence suggesting that in certain oxygen-depleted marine water-column habitats, the majority of microbial eukaryotes are also associated with prokaryotic cells. Ciliates (protists) associated with bacteria were found to be the dominant eukaryotic morphotype in the haloclines of two different deep-sea hypersaline anoxic basins (DHABs) in the Eastern Mediterranean Sea. These findings are compared to associations between ciliates and bacteria documented from the permanently anoxic waters of the Cariaco Basin (Caribbean Sea). The dominance of ciliates exhibiting epibiotic bacteria across three different oxygen-depleted marine water column habitats suggests that such partnerships confer a fitness advantage for ciliates in these environments.