Mitotic and meiotic analyses of the 'large race' of Cobitis striata, a polyploid spined loach of hybrid origin.
The large race of the Cobitis striata complex is a bisexual polyploid population. It is difficult to distinguish this polyploid loach morphologically from a sympatric diploid C. striata, the Biwa small race, indicating the close relationship between these two populations. The polyploid loach does have striata-specific satellite DNAs, but it also harbors C. biwae-related mtDNA. The large race has 2n=4x=98 chromosomes with 56 acrocentric chromosomes. Diploid C. striata has 2n=50 and C. Biwae 2n=48 chromosomes, suggesting the karyotype of polyploid striata as a combination of these two genomes. Meiotic figures showed a few quadrivalent formations besides many bivalents. Many of the quadrivalents were of metacentric chromosomes. Some were, however, made of four acrocentric or of two acro- plus two metacentric chromosomes. Chiasmata were visible in some quadrivalent association. Quadrivalent formation with chiasmata indicates the presence of homologous segments capable of crossing-over between two genomes. Thus, the general polyploid model is also applicable to this case of polyploidy.
Saitoh
Kenji
K
Tohoku National Fisheries Research Institute, Shinhama, Shiogama, Japan. ksaitoh@affrc.go.jp
D000818:Animals; D002875:Chromosomes; D003531:Cypriniformes / Q000235:genetics*; D004272:DNA, Mitochondrial / Q000235:genetics; D005260:Female; D020440:Gene Duplication; D016678:Genome; D006824:Hybridization, Genetic; D008297:Male; D008540:Meiosis; D008938:Mitosis; D011123:Polyploidy
D004272:DNA, Mitochondrial