HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Supplementary Figure Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Clark, C. G. Articles by Tannich, E. Search for Related Content PubMed PubMed Citation Articles by Clark, C. G. Articles by Tannich, E. Agricola Articles by Clark, C. G. Articles by Tannich, E.

New insights into the phylogeny of Entamoeba species provided by analysis of four new small-subunit rRNA genes

¹ Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London WC1E 7HT, UK
² National Public Health Service for Wales Aberystwyth, Bronglais Hospital, Aberystwyth, Ceredigion SY23 1ER, UK
³ Institute of Rural Sciences, University of Wales, Aberystwyth, Ceredigion SY23 3AL, UK
⁴ Department of Molecular Parasitology, Bernhard Nocht Institute for Tropical Medicine, D-20359 Hamburg, Germany
⁵ Medical College, University of Hué, Hué, Vietnam

Correspondence
C. Graham Clark
graham.clark{at}lshtm.ac.uk

Sequences of small-subunit rRNA genes have been obtained for four new isolates of Entamoeba. Phylogenetic analyses give new insights into the evolution of these organisms. A novel Entamoeba from pigs in Vietnam that produces uninucleate cysts proved to be unrelated to other uninucleated cyst-producing species. Revival of the name Entamoeba suis for this organism is proposed. Instead of being related to Entamoeba polecki, it shares a recent common ancestor with the non-encysting Entamoeba gingivalis in a lineage that is basal to the tetranucleate cyst-producing clade. This suggests that species producing cysts with four nuclei are descended from an ancestor that produced cysts with a single nucleus. An Entamoeba from a horse was isolated in culture. No cysts were observed in the original stool sample but the sequence is placed unequivocally within the clade of tetranucleate cyst-producing species with no other sequences being specifically related. Revival of the name Entamoeba equi for this organism is proposed. The Entamoeba ecuadoriensis sequence was found to be the most closely related to Entamoeba histolytica and Entamoeba dispar, as predicted, despite the organism having been an environmental isolate originally assigned to Entamoeba moshkovskii. Finally, a partial E. polecki gene sequence from a pig proved to be virtually identical to that of Entamoeba struthionis from an ostrich, suggesting that the latter name is a synonym.

A colour version of Fig. 1 is available as supplementary material in IJSEM Online.

This article has been cited by other articles:

				B. Tawari, I. K. M. Ali, C. Scott, M. A. Quail, M. Berriman, N. Hall, and C. G. Clark Patterns of Evolution in the Unique tRNA Gene Arrays of the Genus Entamoeba Mol. Biol. Evol., January 1, 2008; 25(1): 187 - 198. [Abstract] [Full Text] [PDF]

				C. G. Clark, J. J. Windsor, and E. Tannich On the identification of some Entamoeba species - response to Ponce-Gordo and Martinez-Diaz Int J Syst Evol Microbiol, June 1, 2007; 57(6): 1176 - 1176. [Full Text] [PDF]

				F. Ponce-Gordo and R. A. Martinez-Diaz On the identification of some Entamoeba species. Comments on a recent paper Int J Syst Evol Microbiol, February 1, 2007; 57(2): 207 - 207. [Full Text] [PDF]