Cytogenetics of the Brazilian Bolitoglossa paraensis (Unterstein, 1930) salamanders (Caudata, Plethodontidae)

Abstract

Plethodontid salamanders of genus Bolitoglossa constitute the largest and most diverse group of salamanders, including around 20% of living caudate species. Recent studies have indicated the occurrence of five recognized species in the Brazilian Amazon Rainforest. We present here the first cytogenetic data of a Brazilian salamander, which may prove to be a useful by contribution to the cytotaxonomy of the genus. Specimens were collected near the “type” locality (Utinga, Belém, PA, Brazil). Chromosomal preparations from duodenal epithelial cells and testes were subjected to Giemsa staining, C-banding and DAPI/CMA3 fluorochrome staining. All specimens showed a karyotype with 13 bi-armed chromosome pairs (2n = 26). Nucleolar Organizer Regions, evidenced by CMA3, were located distally on the long arm of pair 7 (7q). DAPI+ heterochromatin was predominantly centromeric, with some small pericentromeric bands. Although the C-banding patterns of other Bolitoglossa species are so far unknown, cytogenetic studies conducted in other Plethodontid salamanders have demonstrated that pericentromeric heterochromatin is a useful cytological marker for identifying interspecific homeologies. Species diversification is usually accompanied by chromosomal changes. Therefore, the cytogenetic characterization of Bolitoglossa populations from the middle and western Brazilian Amazon Basin could identify differences which may lead to the identification of new species.

Telomere organization and the interstitial telomeric sites involvement in insects and vertebrates chromosome evolution

“…To the best of our knowledge, we found only two reports of the chromosomal mapping of the telomeric motif in the karyotype of Caudata species. While the FISH with (TTAGGG) n motif detected the terminal region of all chromosomes of Bolitoglossa paraenses ( Silva et al, 2014 ), the chromosomal mapping experiments in Cynops pyrrhogaster did not detect any hybridization signal in the karyotype ( Murakami et al, 2007 ). The absence of a hybridization signal with (TTAGGG) n probe in chromosomes of Cynops pyrrhogaster suggests the need for future molecular characterization of terminal regions of these chromosomes to understand better these unexpected results ( Murakami et al , 2007 ).…”