title: Hybrid origin of gynogenetic clones and the introgression of their mitochondrial genome into sexual diploids through meiotic hybridogenesis in the loach, Misgurnus anguillicuadatus.
abstract: In a few Japanese populations of the loach Misgurnus anguillicaudatus (Teleostei: Cobitidae), clonal diploid lineages produce unreduced diploid eggs that normally undergo gynogenetic reproduction; however the origin of these clones remains elusive. Here, we show the presence of two diverse clades, A and B, within this loach species from sequence analyses of two nuclear genes RAG1 (recombination activating gene 1) and IRBP2 (interphotoreceptor retinoid-binding protein, 2) and then demonstrate heterozygous genotypes fixed at the two loci as the evidence of the hybrid nature of clonal lineages. All the clonal individuals were identified by clone-specific mitochondrial DNA haplotypes, microsatellite genotypes, and random amplified polymorphic DNA fingerprints; they commonly showed two alleles, one from clade A and another from clade B, whereas other wild-type diploids possessed alleles from either clade A or B. However, we also found wild-type diploids with clone-specific mitochondrial DNA and nuclear genes from clade B. One possible explanation is an introgression of a clone-specific mitochondrial genome from clonal to these wild-type loaches. These individuals likely arose by a cross between haploid sperm from bisexual B clade males and haploid eggs with clone-specific mtDNA and clade B nuclear genome, produced by meiotic hybridogenesis (elimination of unmatched A genome followed by meiosis after preferential pairing between two matched B genomes) in clone-origin triploid individual (ABB).
authors.affiliation: Faculty and Graduate School of Fisheries Sciences, Hokkaido University, Hakodate, Hokkaido, Japan.
authors.forename: Aya
authors.initials: A
authors.lastname: Yamada
authors.affiliation: Faculty of Veterinary Medicine, Azabu University, Sagamihara, Kanagawa, Japan.
authors.forename: Yukihiro
authors.initials: Y
authors.lastname: Kodo
authors.affiliation: Faculty of Veterinary Medicine, Azabu University, Sagamihara, Kanagawa, Japan.
authors.forename: Masaru
authors.initials: M
authors.lastname: Murakami
authors.affiliation: Faculty and Graduate School of Fisheries Sciences, Hokkaido University, Hakodate, Hokkaido, Japan.
authors.forename: Masamichi
authors.initials: M
authors.lastname: Kuroda
authors.affiliation: Faculty and Graduate School of Fisheries Sciences, Hokkaido University, Hakodate, Hokkaido, Japan.
authors.forename: Takao
authors.initials: T
authors.lastname: Aoki
authors.affiliation: Faculty and Graduate School of Fisheries Sciences, Hokkaido University, Hakodate, Hokkaido, Japan.
authors.forename: Takafumi
authors.initials: T
authors.lastname: Fujimoto
authors.affiliation: Faculty and Graduate School of Fisheries Sciences, Hokkaido University, Hakodate, Hokkaido, Japan.
authors.forename: Katsutoshi
authors.initials: K
authors.lastname: Arai
mesh_terms: D000818:Animals; D003531:Cypriniformes / Q000235:genetics*; D004272:DNA, Mitochondrial / Q000235:genetics; D004171:Diploidy; D005136:Eye Proteins / Q000235:genetics; D005260:Female; D016654:Genes, RAG-1; D054629:Genome, Mitochondrial; D005838:Genotype; D006824:Hybridization, Genetic; D007564:Japan; D008297:Male; D008540:Meiosis; D018895:Microsatellite Repeats; D012177:Retinol-Binding Proteins / Q000235:genetics; D000099214:Retinol-Binding Proteins, Interstitial
chemical_list: D004272:DNA, Mitochondrial; D005136:Eye Proteins; D012177:Retinol-Binding Proteins; D000099214:Retinol-Binding Proteins, Interstitial