Karyotype Analysis of Four Blind Snake Species (Reptilia: Squamata: Scolecophidia) and Karyotypic Changes in Serpentes

In this study, we examined karyotypes of 4 scolecophidian species (Letheobia simonii,Xerotyphlops vermicularis,Indotyphlops braminus, andMyriopholis macrorhyncha) and performed FISH with 18S-28S rDNA as well as microchromosomal and Z chromosome-linked genes ofElaphe quadrivirgata (Alethinophidia) to investigate the karyotype evolution in the scolecophidian lineage. Diploid chromosome numbers ofX. vermicularis andL. simonii were 30 (16 macrochromosomes and 14 microchromosomes) and 32 (16 macrochromosomes and 16 microchromosomes), respectively. The karyotype of a femaleM. macrorhyncha consisted of 15 macrochromosomes and 19 microchromosomes, including a heterochromatic microchromosome, indicating the presence of a heteromorphic chromosome pair.E. quadrivirgata Z-linked genes mapped to chromosome 4 ofM. macrorhyncha, not to the heteromorphic pair. Therefore,M. macrorhyncha may have differentiated ZW sex chromosomes which are not homologous to those ofE. quadrivirgata. One of the E. quadrivirgata microchromosomal genes mapped to the terminal region of chromosome 4q inX. vermicularis, suggesting that fusions between microchromosomes and macrochromosomes occurred in this species. rDNA was localized in different macrochromosomal pairs in the 2 diploid scolecophidian snakes examined here, whereas the gene location in a microchromosomal pair was conserved in 5 alethinophidian species examined. These results might imply the occurrence of chromosome fusions in the scolecophidian lineage...

Source: Cytogenetic and Genome Research - February 12, 2019 Category: Genetics & Stem Cells Source Type: research