Classical molecular cytogenetics of spiny-tailed house gecko, Hemidactylus frenatus (Squamata, Gekkonidae) from Thailand

Abstract

The subject of research was a molecular cytogenetic investigation of the Hemidactylus frenatus or spiny-tailed house gecko. Ag-nucleolar organizer region (NOR) banding, fluorescence in situ hybridization (FISH), and conventional staining were used to mitotic chromosomes prepared directly from bone marrow. According to the findings, there were 40 diploid chromosomes (2n). For both sexes, the fundamental number was 74. The karyotype formula, consisting of metacentric, submetacentric, acrocentric, and telocentric chromosomes, is as follows: 2n(40)=10m+4sm+20a+6t or L2m+L4sm+L8a+M6a+S8m+S6a+S6t. The NORs appeared at the telomere of the long arm of chromosome pair 16. Using six probes, (A)30, (CA)15, (GC)15, (CAC)10, (GAA)10, and (GAG)10, FISH mapping of microsatellite repeat modes was conducted. The results showed specific signals of (CA)15, (GC)15, (CAC)10, (GAA)10, and (GAG)10 on chromosome pairs, whereas the (A)30 probe spread onto metaphase. H. frenatus chromosomes are primarily acrocentric, and all of their chromosomes have distinct patterns in their short and long arms. This characteristic is maintained by the main evolutionary line of the gecko group, including its early predecessors. The evolution of the karyotype in the genus Hemidactylus involved the breaking off of chromosomal fragments and the rearrangement of centromeres, resulting in different numbers and shapes of chromosomes within the genus.