Expression of common fragile sites in two Ceboidea species: Saimiri boliviensis and Alouatta caraya (Primates : Platyrrhini)

Fragile sites are points of preferential breakage that may be involved in c hromosome rearrangements. Induction of common fragile sites (c-fra) and spo ntaneous breakage were analyzed in two New World Monkeys species: Saimiri b oliviensis (SBO) and Alouatta caraya (ACA). Spontaneous chromosome aberrati ons were analyzed on untreated lymphocyte cultures with Brogger's formula ( 1977). SBO presented a low level of spontaneous breakage, while higher freq uencies were detected in ACA in which bands 1q23; 2q13 and 11q19 were signi ficantly affected (p < 0.01). The populational distribution of c-fra was an alyzed by the Chi(2) test in FUdR plus caffeine treated cultures. A total o f 21 c-fra was identified in SBO and 24 in ACA. Fragile sites A(1)q33, B(1) p21, B(4)p14, C(3)q23 and C(5)q22 were identified in all analyzed SBO speci mens. The most frequent c-fra identified in ACA specimens were 1q23, 1q31, 1q33, 2q22, 8q14, 12q31, 13q22, 14q15 and Xq22. Fragile sites A(1)q31, A(1) q33, B(1)q14, B(3)q13, B(4)q21 and Xq22 identified in SBO and 1q31, 1q33, 2 q22, 4q21, 6q13, 13q22 and Xq22 from ACA were the most conserved sites. A l ow coincidence between the location of c-fra and that of heterochromatin an d breakpoints involved in euchromatic rearrangements known for these genera , was established.