title: Inbreeding Ratio and Genetic Relationships among Strains of the Western Clawed Frog, Xenopus tropicalis.
abstract: The Western clawed frog, Xenopus tropicalis, is a highly promising model amphibian, especially in developmental and physiological research, and as a tool for understanding disease. It was originally found in the West African rainforest belt, and was introduced to the research community in the 1990s. The major strains thus far known include the Nigerian and Ivory Coast strains. However, due to its short history as an experimental animal, the genetic relationship among the various strains has not yet been clarified, and establishment of inbred strains has not yet been achieved. Since 2003 the Institute for Amphibian Biology (IAB), Hiroshima University has maintained stocks of multiple X. tropicalis strains and conducted consecutive breeding as part of the National BioResource Project. In the present study we investigated the inbreeding ratio and genetic relationship of four inbred strains at IAB, as well as stocks from other institutions, using highly polymorphic microsatellite markers and mitochondrial haplotypes. Our results show successive reduction of heterozygosity in the genome of the IAB inbred strains. The Ivory Coast strains clearly differed from the Nigerian strains genetically, and three subgroups were identified within both the Nigerian and Ivory Coast strains. It is noteworthy that the Ivory Coast strains have an evolutionary divergent genetic background. Our results serve as a guide for the most effective use of X. tropicalis strains, and the long-term maintenance of multiple strains will contribute to further research efforts.
authors.affiliation: Institute for Amphibian Biology, Graduate School of Science, Hiroshima University, Higashi-Hiroshima, Hiroshima, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Igawa
authors.affiliation: Institute for Amphibian Biology, Graduate School of Science, Hiroshima University, Higashi-Hiroshima, Hiroshima, Japan.
authors.forename: Ai
authors.initials: A
authors.lastname: Watanabe
authors.affiliation: Institute for Amphibian Biology, Graduate School of Science, Hiroshima University, Higashi-Hiroshima, Hiroshima, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Suzuki
authors.affiliation: Institute for Amphibian Biology, Graduate School of Science, Hiroshima University, Higashi-Hiroshima, Hiroshima, Japan.
authors.forename: Akihiko
authors.initials: A
authors.lastname: Kashiwagi
authors.affiliation: Institute for Amphibian Biology, Graduate School of Science, Hiroshima University, Higashi-Hiroshima, Hiroshima, Japan.
authors.forename: Keiko
authors.initials: K
authors.lastname: Kashiwagi
authors.affiliation: School of Biological Sciences, Institute of Biomedical and Biomolecular Science, University of Portsmouth, Portsmouth, United Kingdom.
authors.forename: Anna
authors.initials: A
authors.lastname: Noble
authors.affiliation: School of Biological Sciences, Institute of Biomedical and Biomolecular Science, University of Portsmouth, Portsmouth, United Kingdom.
authors.forename: Matt
authors.initials: M
authors.lastname: Guille
authors.affiliation: The Wellcome Trust/Cancer Research UK Gurdon Institute, The Henry Wellcome Building of Cancer and Developmental Biology, University of Cambridge, Cambridge, United Kingdom.
authors.forename: David E
authors.initials: DE
authors.lastname: Simpson
authors.affiliation: Bell Center for Regenerative Biology and Tissue Engineering and National Xenopus Resource, Marine Biological Laboratory, Woods Hole, MA, United States of America.
authors.forename: Marko E
authors.initials: ME
authors.lastname: Horb
authors.affiliation: Department of Health Sciences, Faculty of Human Culture & Science, Prefectural University of Hiroshima, Hiroshima, Japan.
authors.forename: Tamotsu
authors.initials: T
authors.lastname: Fujii
authors.affiliation: Institute for Amphibian Biology, Graduate School of Science, Hiroshima University, Higashi-Hiroshima, Hiroshima, Japan.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Sumida
mesh_terms: D000818:Animals; D002874:Chromosome Mapping; D005260:Female; D005819:Genetic Markers / Q000235:genetics; D054629:Genome, Mitochondrial / Q000235:genetics; D060005:Genotyping Techniques; D007178:Inbreeding; D008297:Male; D018895:Microsatellite Repeats / Q000235:genetics; D010802:Phylogeny; D011110:Polymorphism, Genetic; D013045:Species Specificity; D014981:Xenopus / Q000235:genetics*
chemical_list: D005819:Genetic Markers