Chromosomal characteristics of NORs and karyological analysis of Tokay Gecko, Gekko gecko (Gekkonidae, Squamata) from mitotic and meiotic cell division

Abstract

Chromosomal characteristics of nucleolar organizer regions/NORs and karyological analysis of the Tokay gecko (Gekko gecko) from Khon Kaen Province, northeast Thailand was studied. Gecko chromosome preparations were conducted by squash technique from bone marrow and testis. Conventional staining and Ag-NOR banding techniques were applied to stain the chromosome with Giemsa's solution. The results showed that the number of diploid chromosomes is 2n=38, while the fundamental number (NF) is 50 in both males and females. The types of chromosomes were 2 large metacentric, 4 large submetacentric, 4 large telocentric, 6 medium telocentric, 4 small metacentric, 2 small acrocentric, and 16 small telocentric chromosomes. NORs are located at the secondary constriction to the telomere on long arm of the largest telocentric chromosome pair 4. There are no sex differences in karyotypes between males and females. We found that during metaphase I the homologous chromosomes showed synapsis, which can be defined as 19 ring bivalents and 19 haploid chromosomes (n=19) at metaphase II as a diploid species. The karyotype formula is as follows: 2n (38)=L2 m+L4 sm+Lt4 +Mt6 +S4 m+Sa 2+St 16