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Phylogenetic relationships of three hymenolepidid species inferred from nuclear ribosomal and mitochondrial DNA sequences

Published online by Cambridge University Press:  01 December 1997

M. OKAMOTO
Affiliation:
Institute of Experimental Animal Sciences, Osaka University Medical School, Suita, Osaka 565, Japan
T. AGATSUMA
Affiliation:
Department of Bioresource Chemistry, Obihiro University of Agriculture and Veterinary Medicine, Obihiro 080, Japan
T. KUROSAWA
Affiliation:
Institute of Experimental Animal Sciences, Osaka University Medical School, Suita, Osaka 565, Japan
A. ITO
Affiliation:
Department of Parasitology, Gifu University School of Medicine, Gifu 500, Japan

Abstract

Three hymenolepidid tapeworms, Hymenolepis diminuta, H. nana and H. microstoma, are commonly maintained in laboratory rodents and used in many experimental model systems of tapeworm infections. We examined partial sequences from the mitochondrial cytochrome c oxidase subunit 1 (CO1) gene and nuclear ribosomal internal transcribed spacer 2 (ITS2) sequences to infer phylogenetic relationships of the 3 hymenolepidid species. Parts of the CO1 gene and ITS2 were amplified by PCR and sequenced directly. The CO1 gene sequence obtained was the same in length (391 bp) among all specimens. In the case of ITS2, however, several insertions and deletions were detected (671–741 bp) not only among species but also between an American isolate and a Japanese isolate of H. diminuta. Percentage nucleotide differences between H. diminuta and H. microstoma, or H. diminuta and H. nana were 16·6–18·2% for the CO1 gene and 21·3–22·9% for ITS2. The differences in both sequences between H. microstoma and H. nana were about 14%. Phylogenetic trees inferred from both of the nucleotide sequences showed similar topology, and suggest that H. diminuta may have diverged from the common ancestral line the earliest, and that H. nana is closer to H. microstoma than to H. diminuta.

Type
Research Article
Copyright
1997 Cambridge University Press

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