New insights into the phylogeny of Entamoeba species provided by analysis of four new small-subunit rRNA genes.
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.
Clark
C Graham
CG
Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London WC1E 7HT, UK.
Kaffashian
Farrokh
F
Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London WC1E 7HT, UK.
Tawari
Blessing
B
Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London WC1E 7HT, UK.
Windsor
Jeffrey J
JJ
National Public Health Service for Wales Aberystwyth, Bronglais Hospital, Aberystwyth, Ceredigion SY23 1ER, UK.
Twigg-Flesner
Anke
A
Institute of Rural Sciences, University of Wales, Aberystwyth, Ceredigion SY23 3AL, UK.
Davies-Morel
Mina C G
MCG
Institute of Rural Sciences, University of Wales, Aberystwyth, Ceredigion SY23 3AL, UK.
Blessmann
Joerg
J
Department of Molecular Parasitology, Bernhard Nocht Institute for Tropical Medicine, D-20359 Hamburg, Germany.
Ebert
Frank
F
Department of Molecular Parasitology, Bernhard Nocht Institute for Tropical Medicine, D-20359 Hamburg, Germany.
Peschel
Babett
B
Department of Molecular Parasitology, Bernhard Nocht Institute for Tropical Medicine, D-20359 Hamburg, Germany.
Van
An Le
AL
Medical College, University of Hué, Hué, Vietnam.
Jackson
Colin J
CJ
Institute of Rural Sciences, University of Wales, Aberystwyth, Ceredigion SY23 3AL, UK.
Macfarlane
Lorna
L
National Public Health Service for Wales Aberystwyth, Bronglais Hospital, Aberystwyth, Ceredigion SY23 1ER, UK.
Tannich
Egbert
E
Department of Molecular Parasitology, Bernhard Nocht Institute for Tropical Medicine, D-20359 Hamburg, Germany.
D000818:Animals; D001483:Base Sequence; D016054:DNA, Protozoan / Q000032:analysis*; D004747:Entamoeba / Q000145:classification* / Q000235:genetics; D020459:Genes, rRNA / Q000235:genetics*; D008969:Molecular Sequence Data; D010802:Phylogeny
D016054:DNA, Protozoan