Chromosomal homologies between Cebus and Ateles (primates) based on ZOO-FISH and G-banding comparisons

ZOO-FISH (Fluorescent "in vitro" hybridization) was used to establish the chromosomal homology between humans (HSA) and Cebus nigrivitatus (CNI) and Ateles belzebuth hybridus (ABH). These two species belong to different New World monkey families (Cebidae and Atelidae, respectively) which differ greatly in chromosome number and in chromosome morphology. The molecular results were followed by a detailed banding analysis. The ancestral karyotype of Cebus was then determined by a comparison of in situ hybridization results, as well as chromosomal morphology and banding in other Platyrrhini species. The karyotypes of the four species belonging to the genus Cebus differ from each other by three inversions and one fusion as well as in the location and amounts of heterochromatin. Results obtained by ZOO-FISH in ABH are in general agreement with previous gene-mapping and in situ hybridization data in Ateles, which show that spider monkeys have highly derived genomes. The chromosomal rearrangements detected between HSA and ABH on a band-to-band basis were 27 fusions/fissions, 12 centromeric shifts, and six pericentric inversions. The ancestral karyotype of Cebus was then compared with that of Ateles. The rearrangements detected were 20 fusions/fissions, nine centromeric shifts, and five inversions. Atelidae species are linked by a fragmentation of chromosome 4 into three segments forming an association of 4/15, while Ateles species are linked by 13 derived associations. The results also helped clarify the content of the ancestral platyrrhine karyotype and the mode of chromosomal evolution in these primates. In particular, associations 2/16 and 5/7 should be included in the ancestral karyotype of New World monkeys.

Chromosome abnormalities in peripheral blood lymphocytes from Cebus apella (Cebidae, Platyrrhini) after X-ray irradiation

In this paper, we describe the results of a qualitative and quantitative study of chromosomal reorganizations observed in X-irradiated (1Gy and 2Gy) and cultured lymphocytes from Cebus apella. A total of 646 breakpoints have been detected, identified and localized in the ideogram of the species. The breakpoint distribution along chromosomes, p and q arms, and bands is not random. Chromosomes #11, #12 and chromosome arms 1p, 12p, 13p, 15p, 11q, and 12q are significantly more affected than expected, while chromosome #19 and chromosome arm 19q are less affected. Terminal regions of chromosome arms accumulate a higher number of breakpoints than the rest of the chromosome (37.82%). A high percentage (93.66%) of breakpoints is found in G negative bands.