Implication of fragile sites and intrachromosomal telomeric (TTAGGG)n sequences in Primate chromosome evolution

The concentration of evolutionary breakpoints in Primate karyotypes in some particular regions or chromosome bands suggests that these chromosomal regions are more prone to breakage. In this work our aim is to test whether fragile sites (FSs) and intrachromosomal telomeric sequences (TTAGGG)n are implicated in the evolutionary process of Primate chromosomes. For this purpose, we have analyzed: (a) the cytogenetic expression of aphidicolininduced FSs at two different aphidicolin concentrations (0.1μmol/L and 0.2μmol/L) in three specimens of Cebus apella and Cebus nigrivittatus (F. Cebidae, Platyrrhini) and four specimens of Mandrillus sphinx (F. Cercopithecidae, Catarrhini), and (b) intrachromosomal telomeric sequences (ITSs) by fluorescent in situ hybridization with a synthetic (TTAGGG)n probe in C. apella chromosomes. The use of a multinomial FSM statistical model allowed us to identify 53 FSs in C. apella, 16 FSs in C. nigrivittatus and 50 FSs in M. sphinx. As expected, all telomeres hybridized with the probe, and 55 intrachromosomal loci were also detected. About 40% of the fragile sites detected in the Primate species studied are conserved in the corresponding homologous human chromosomes and that a high number of evolutionary chromosomal reorganizations is located in chromosome bands that express fragile sites and/or contain intrachromosomal telomeric sequences.