RESUMO
The course of chromosome evolution in small apes is still not clear, though painting analyses have opened the way for elucidating the puzzle. Even the C-banding pattern of the lar-group of gibbons (the genus Hylobates) is not clarified yet, although our previous studies suggested that lar-group gibbons have a unique C-banding pattern. We therefore made observations to establish C-banded karyotypes of the agile gibbons included in the lar-group. The data were compared with those of siamangs (the genus Symphalangus), which carry distinctive C-bands, to determine the chromosomal patterns in each group. C-banded chromosomes of agile gibbons showed several terminal, interstitial and paracentric bands, whose patterns are specific for each chromosome, whereas the C-bands of siamangs were located only at the terminal and centromeric regions in most chromosomes. Moreover, the C-bands of agile gibbons and siamangs were shown to be G+C-rich and A+T-rich DNA, respectively, by DAPI/C-band sequential staining. Additionally, PRINS labelling with a telomere primer revealed that agile gibbons have telomeric DNA only at chromosome ends where there is no C-band (non-telomeric heterochromatin), whereas the telomeric DNA of siamangs is located in the terminal C-banded regions (telomeric heterochromatin). Although the evolutionary mechanisms in small apes are still unknown, C-banding patterns and distribution of telomeric DNA sequences should provide valuable data to deduce the evolutionary pathways of small apes.
Assuntos
DNA/genética , Heterocromatina/genética , Hominidae/genética , Hylobates/genética , Telômero/genética , Sequência Rica em At , Animais , Centrômero , Bandeamento Cromossômico , Cromossomos , Sequência Rica em GC , Cariotipagem , Filogenia , Marcação in Situ com PrimersRESUMO
C-banding analysis with 47 gibbons of the subgenus Hylobates (Hylobates) (44-chromosome gibbons) uncovered that the gibbons had a characteristic complicated C-banding pattern. The C-band pattern also revealed that a whole-arm translocation (WAT) between chromosomes 8 and 9 existed only in the species H. agilis (agile gibbon). Comprehensive consideration allows postulation that the translocation seemed to be restricted to two subspecies: H. agilis agilis (mountain agile gibbon) and H. agilis unko (lowland agile gibbon), found in Sumatra and part of the Malay Peninsula. Moreover, combined intensive analyses of C-banding and chromosome painting provided strong evidence for a plausible evolutionary pathway of chromosome differentiation of chromosomes 8 and 9. The C-banded morph 8M(t/c) seemed to be the primary type of chromosome 8 in the subgenus and to have altered into the three morphs through three pericentric inversions. The newest morph (8A(M/ci)) produced by the third inversion exchanged the long arm for chromosome 9, and subsequently constructed the WAT morphs of 8/9A(Mc/ct) and 9/8M(i/ci).
