Comparative cytogenetic analysis on four tree frog species (Anura, Hylidae, Hylinae) from Brazil

Abstract

A comparative cytogenetic analysis was carried out on four Hylinae tree frogs from Brazil (Aparasphenodon brunoi, Corythomantis greeningi, Osteocephalus langsdorffii, and Scinax fuscovarius) using Giemsa staining, BrdU replication banding, Ag-NOR staining, C-banding, DAPI and CMA₃ fluorochrome staining, and fluorescence in situ hybridization (FISH) with an rDNA probe. All the species share closely similar 2n = 24 karyotypes, almost indistinguishable by standard staining. The technique of BrdU incorporation allowed the identification of each pair of homologs and the establishment of extensive homeology for the great majority of the chromosomes, mainly of A. brunoi, C. greeningi, and O. langsdorffii. Despite highly conserved replication banding patterns, the use of the other banding techniques disclosed some minor differences, which reinforces the importance of extensive cytogenetic analyses for the karyotypic characterization of Anuran species. The present cytogenetic data confirm the closer proximity of A. brunoi, C. greeningi, and O. langsdorffii, whereas S. fuscovarius is phylogenetically more distant.

Comparative analysis based on replication banding reveals the mechanism responsible for the difference in the karyotype constitution of treefrogs Ololygon and Scinax (Arboranae, Hylidae, Scinaxinae)

“…As already pointed out by Cardozo et al (2011) and subsequently confirmed in other works, the species of Ololygon (the former Scinax catharinae clade) have NORs in chromosome pair 6, whereas the species of Scinax (the former Scinax ruber clade) generally have this marker in the chromosome pair 11, which also indicates the conservation of this character to cytogenetically differentiate species of both groups. It is important to note that a chromosome constitution with 2n = 24, including the position of NORs, which is characteristic of currently recognized Scinax species, is observed in the vast majority of representatives of hylinaes sharing a 2n = 24 (Kasahara et al 2003, Cardozo et al 2011. It can consequently be assumed that the chromosome constitution characteristic of the Scinax genus (the former Scinax ruber clade) would be the ancestor, while that presented by the species of Ololygon (the former Scinax catharinae clade) would be the derived condition, as it was previously pointed out by Cardozo et al (2011) In this case, the process of differentiating the karyotype of both groups was probably the deletion and not the addition of repetitive DNA in the short arms of chromosomes 1 and 2, in an ancestral karyotypic form similar to that exhibited by the current Scinax species and other Hylinae.…”

“…The sample includes species whose chromosomes are described for the first time in this paper: Scinax caldarum and S. crospedospilus; specimens belonging to species already described in Cardozo et al (2011) 2 -specimens belonging to species already described in Cardozo et al (2011) but collected in non studied populations; 3 -additional banding data of specimens from the analyzed sample in Cardozo et al (2011); 4 -specimen reanalyzed from Kasahara et al (2003) sample; * identification based on the COI sequencing from tissue sample. Kasahara et al (2003): the replication bands of this specimen were reanalyzed herein because its high resolution banding was more appropriate for comparative analysis.…”

“…Kasahara et al (2003): the replication bands of this specimen were reanalyzed herein because its high resolution banding was more appropriate for comparative analysis. The animals were identified by Dr. Célio F. B. Haddad and the vouchers were fixed in formalin (10%), preserved in 70% ethanol and deposited in the amphibian collection CFBH of the Departamento de Zoologia, Instituto de Biociências, UNESP, Rio Claro, SP, Brazil.…”

“…In the present work our efforts were the use of replication banding after 5-bromodeoxiuridine treatment, an useful approach to identify homeologous chromosomes (Kasahara et al 2003, Silva et al 2004, Gruber et al 2007, Gazoni et al 2012, Gruber et al 2013). This methodology is very effective for comparative analyses in fishes, amphibians, and reptiles due to the difficulty in producing classical Q, G, and R banding patterns in the chromosomes of the ectothermic vertebrates (Sumner 2003).…”

Dynamics of chromosomal evolution in the genus Hypsiboas (Anura: Hylidae)

“…Nonetheless, with improvements in the methods of chromosomal banding and molecular cytogenetics, a remarkable variability in chromosomal microstructure has been reported, which allowed a refined identification of species and their geographical variants, thereby serving as a reliable tool for taxonomic studies (Kasahara et al, 2003;Siqueira et al, 2004).…”