Cytogenetic characterisation and chromosomal mapping of microsatellite and telomeric repeats in two gecko species (Reptilia, Gekkonidae) from Thailand

Abstract

Studies of chromosomes of Cyrtodactylus jarujini Ulber, 1993 and C. doisuthep Kunya et al., 2014 to compare microsatellite and TTAGGG sequences by classical and molecular techniques were conducted in Thailand. Karyological typing from a conventional staining technique of C. jarujini and C. doisuthep showed diploid chromosome numbers of 40 and 34 while the Fundamental Numbers (NF) were 56 in both species. In addition, we created the chromosome formula of the chromosomes of C. jarujini showing that 2n (40) = L^sm ₁ + L^sm ₂ + L^t ₃ + M^m ₁ + M^t ₄ + S^m ₂ + S^a ₂ + S^t ₅ while that of C. doisuthep was 2n (34) = L^sm ₃ + L^m ₂ + L^t ₃ + M^m ₁ + M^t ₂ + S^m ₄ + S^a ₁ + S^t ₁. Ag-NOR staining revealed NOR-bearing chromosomes in chromosome pairs 13 and 14 in C. jarujini, and in chromosome pairs 9 and 13 in C. doisuthep. This molecular study used the FISH technique, as well as microsatellite probes including (A)₂₀, (TA)₁₅, (CGG)₁₀, (CGG)₁₀, (GAA)₁₀, (TA)₁₅ and TTAGGG repeats. The signals showed that the different patterns in each chromosome of the Gekkonids depended on probe types. TTAGGG repeats showed high distribution on centromere and telomere regions, while (A)₂₀, (TA)₁₅, (CGG)₁₀, (CGG)₁₀, (GAA)₁₀ and (TA)₁₅ bearing dispersed over the whole genomes including chromosomes and some had strong signals on only a pair of homologous chromosomes. These results suggest that the genetic linkages have been highly differentiated between the two species.

Keywords: Ag-NOR; Cyrtodactylus doisuthep; Cyrtodactylus jarujini; FISH microsatellite; karyotype.