Cytogenetic characterization of Ameivula ocellifera (Spix, 1825) (Squamata, Teiidae) from the brazilian northeast

Ameivula is as a new genus of Teiidae family that emerged after extensive revision of species that comprised the former complex of species called Cnemidophorus group. Its species has a wide distribution from the northeast of Brazil to northern Argentina. Cytogenetic studies in the Teiidae family have shown that karyotypical data are important tools in phylogenetic and systematic studies within this group allowing to determine the position of species in the family. Thus, this study aimed to describe the karyotype of Ameivula ocellifera (Spix, 1825) from Picos, Piauí state in the Brazilian Northeast. Specimens were collected from August 2014 to October 2015 using interception traps and pitfalls, mounted randomly along the Caatinga area. The animals were collected and transported to Federal Institute of Piauí, campus Picos, where was carried out all laboratory procedures. Individuals analyzed showed a diploid number of 2n = 50 for both sexes, with karyotype composed by 30 macrochromosomes and 20 microchromosomes of telocentric and subtelocentric types. There were no heteromorphic sex chromosomes in the studied specimens. C-band technique evidenced the heterochromatic blocks in pericentromeric and telomeric regions of chromosomes. The nucleolar organizing regions appeared as a simple unit located at the terminal portion of the long arm of chromosomal pair number 5. The chromosomal characteristics of A. ocellifera analyzed do not show divergences regarding individuals from other regions. However, the nucleolar organizing regions seems to be a good chromosomal marker that permits to distinguish the species already studied

Cytogenetic study in the Brazilian semiarid lizard Tropidurus hispidus (Squamata, Tropiduridae)

Different classes of repetitive DNA sequences are found in eukaryotes, often composing substantial portions of the genome, associated with their important role in the structural and functional genome organization. In this work, we mapped repetitive DNA sequences (18S rDNA, microsatellites and telomeric motifs) in the karyotype of Tropidurus hispidus, a species of lizard from the Brazilian semiarid region. We found a diploid number of 2n = 36 (6 pairs of biarmed macrochromosomes and 12 pairs of microchromosomes). The 18S rDNA clusters were localized at the subterminal region of the long arm of pair 2. The telomeric probes produced signals at terminal, interstitial and centromeric positions of some chromosome pairs, which might indicate the occurrence of chromosomal rearrangements via chromosome fusions. Microsatellite sequences were found in at least two distinct patterns - clustered in the telomeric/pericentromeric regions or observed as scattered signals in the chromosomes. This study represents an initial step to explore the evolutionary dynamics of repetitive sequences in the Tropidurus genus and considering the scarcity of data concerning the chromosomal mapping of repetitive sequences in Tropiduridae species, it reinforces the importance of integrating other methodologies, including the isolation and physical mapping of different repetitive DNA sequences, contributing to understanding the patterns of karyotypic evolution in lizards.Asociación Herpetológica Argentin