2ª REUNIÃO BRASILEIRA DE CITOGENÉTICA
28 a 30 de agosto 2011 • Águas de Lindóia • SP
Cytogenetic analysis of the species Dendropsophus seniculus (Anura,
Hylidae): a contribution for the 30-chromosome genus Dendropsophus
Teixeira, LSR1; Tacioli, A2; Lourenço, LB1
Departamento de Anatomia, Biologia Celular, Fisiologia e Biofísica – Instituto de Biologia Universidade Estadual de Campinas (UNICAMP), Campinas – SP;
1
Departamento de Zoologia – Instituto de Biociências – Universidade Estadual Paulista “Júlio de Mesquita Filho” (UNESP),
Campus de Rio Claro, Rio Claro – SP
2
[email protected]
Keywords: Dendropsophus seniculus, chromosome, cytogenetics, karyotype, Hylidae
The monophyletic genus Dendropsophus (Anura, Hylidae) includes 92 neotropical species divided into nine groups and
is distributed from Central America to South America. This genus has recently been revalidated to include species with a
proven or presumably present chromosome number 2n=30. In spite of that, only about 30% of the Dendropsophus species
has been karyotyped, and, in most cases, only the number of chromosomes and chromosome morphology are described.
Although based on little data, it is already possible to note an intriguing variation in the number of telocentric chromosomes among different species. Dendropsophus seniculus is currently allocated in the species group D. marmoratus, along with
seven other species. Only two of them, Dendropsophus marmoratus and Dendropsophus nahedereri, have already been studied
cytogenetically. The present study aimed to characterize the Dendropsophus seniculus species cytogenetically, based on four
specimens from Ribeirão Grande, São Paulo State. The chromosome preparations were obtained from cell suspensions of
intestinal epithelium and subjected to conventional Giemsa staining, C-banding, silver staining using the Ag-NOR method,
and DAPI staining of C-banded metaphases. All specimens had a 2n=30 karyotype. Five pairs of chromosomes were classified
as submetacentric, five pairs as metacentric, and five pairs as telocentric. The C-banding technique revealed only the centromeric heterochromatin in all the chromosomes, which were also stained with DAPI. In Giemsa-stained metaphases, a secondary constriction was observed on the long arm of a metacentric pair, which was tentatively classified as number 8. After silver
staining, this secondary constriction was detected as a Nucleolar Organizer Region (NOR). This NOR-bearing chromosome
is similar to a medium-sized submetacentric chromosome of D. marmoratus, in which a secondary constriction could be seen
interstitially in the long arm, although it had not been discussed by the authors who described that karyotype. Interestingly,
in D. nahdereri, the NOR occupies a very distinct site, located on the short arm of the submetacentric pair 1. The number of
telocentric chromosomes in Dendropsophus seniculus was the same as observed in D. nahdereri and D. marmoratus. Curiously,
several species from other groups also show five telocentric pairs, such as D. sanborni (D. gr. microcephalus), and D. labialis
(D. gr. labialis). Future work is necessary to clarify cytogenetic differences within this species group and possible homeologies
among the telocentric pairs of different species.
Financial Support: Fapesp, CAPES
CA012