Abstract
Podocnemis expansa and P. unifilis present 2n = 28 chromosomes, a diploid number similar to those observed in other species of the genus. The aim of this study was to characterize these two species using conventional staining and differential CBG-, GTG and Ag-NOR banding. We analyzed specimens of P. expansa and P. unifilis from the state of Tocantins (Brazil), in which we found a 2n = 28 and karyotypes differing in the morphology of the 13th pair, which was submetacentric in P. expansa and telocentric in P. unifilis. The CBG-banding patterns revealed a heterochromatic block in the short arm of pair 13 of P. expansa and an interstitial one in pair 13 of P. unifilis, suggesting a pericentric inversion. Pair 14 of P. unifilis showed an insterstitial band in the long arm that was absent in P. expansa, suggesting a duplication in this region. Ag-NORs were observed in the first chromosome pair of both species and was associated to a secondary constriction and heterochromatic blocks.
Highlights
Cytogenetic studies on species of the order Testudines are very scarce when compared to other orders of the class Reptilia (Barros et al, 1976)
According to Ramírez et al (2008), the genus Podocnemis includes six species (P. expansa, P. vogli, P. sextuberculata, P. unifilis, P. lewyana, P. erythrocephala), which have diverged in this sequence according to molecular phylogenetic data
The samples were obtained from six specimens of P. expansa from the Experimental Station of the Universidade Federal do Tocantins - UFT (Palmas-TO) (IBAMA license number 028/05-RAN), and seven fertilized eggs of P. unifilis from the Tocantins River in the municipality of Ipueiras-TO
Summary
Cytogenetic studies on species of the order Testudines are very scarce when compared to other orders of the class Reptilia (Barros et al, 1976). Cytogenetic studies in Podocnemis have revealed that species of this genus present the same diploid number of 2n = 28 (Rhodin et al, 1978, Ortiz et al, 2005, Fantin and Monjeló, 2011). Huang and Clark (1969) described the karyotypes of P. expansa and P. unifilis, which were characterized by a comparatively low diploid number, the lack of microchromosomes and of sex chromosomes and by the presence of several secondary constrictions.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
