Biol. Bull. Sign up for etocs!
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

This Article
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Katayama, T.
Right arrow Articles by Yamamoto, M.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Katayama, T.
Right arrow Articles by Yamamoto, M.

The Biological Bulletin, Vol 189, Issue 2 81-90, Copyright © 1995 by Marine Biological Laboratory

ECOLOGY AND EVOLUTION

Phylogenetic Position of the Dicyemid Mesozoa Inferred from 18S rDNA Sequences

T. Katayama, H. Wada, H. Furuya, N. Satoh and M. Yamamoto
Ushimado Marine Laboratory, Okayama University, Okayama 701-43

The dicyemid mesozoa, obligate symbionts in the cephalopod kidney, are simply organized multicellular animals. They have long been the subject of phylogenetic debates. Some authors have suggested that dicyemids represent an offshoot from an early metazoan ancestor. Other workers considered them to be degenerated progeny of higher metazoa, possibly parasitic trematodes. We determined the almost complete nucleotide sequences of 18S rDNA in two species of dicyemid, Dicyema orientale and Dicyema acuticephalum, isolated purely from cephalopod urine. We compared these sequences with sequences determined in the present study from three flatworm species, as well as with a variety of eukaryote sequences obtained from databases. The phylogenetic trees reconstructed with the use of the neighbor-joining, maximum-parsimony, and maximum-likelihood methods indicated that the dicyemids belong among the triploblastic animals (Bilateria). However, we cannot firmly establish the position of the dicyemids within the Bilateria because we cannot ignore the problem of long branch attraction between the myxozoans, dicyemids, nematodes, and acoel flatworms. The present results favor the hypothesis that the dicyemids do not represent an early divergent metazoan group, but rather a group degenerated from a triploblastic ancestor.


This article has been cited by other articles:


Home page
 Biol. Bull.Home page
H. Furuya, F. G. Hochberg, and K. Tsuneki
Developmental Patterns and Cell Lineages of Vermiform Embryos in Dicyemid Mesozoans
Biol. Bull., December 1, 2001; 201(3): 405 - 416.
[Abstract] [Full Text] [PDF]

Home page
 Mol Biol EvolHome page
C. Berney, J. Pawlowski, and L. Zaninetti
Elongation Factor 1-Alpha Sequences Do Not Support an Early Divergence of the Acoela
Mol. Biol. Evol., July 1, 2000; 17(7): 1032 - 1039.
[Abstract] [Full Text] [PDF]


HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Copyright © 1995 by the Marine Biological Laboratory.