HETEROCHROMATIN AND SPECIATION IN NEOTROPICAL PRIMATES: THE Cebus CASE (PLATYRRHINI: CEBIDAE).

NIEVES, MARIELA; DE OLIVERA, EDIVALDO; AMARAL, PAULO; NAGAMACHI, CLEUSA; PIECZARKA, JULIO; MUHLMANN, MARÍA C.; MUDRY, MARTA D.

Trelew, Chubut

Congreso; XXXIV Congreso Argentino de Genética; 2005

Sociedad Argentina de Genética

Neotropical Primates (NP) karyotypes are highly variable, showing modal numbers ranging from 32 to 62 as well as structural rearrangements and, sometimes, minute chromosomes. Banding techniques and restriction enzymes digestion demonstrated that great variability of heterochromatin exist among NP, particularly in the repeated sequences regions. Not only regarding its amount but also its composition. Cebus, considered the genus with the most ancestral karyotype among NP, shows the greatest amount of constitutive heterochromatin in every reported karyotype. Trying to interprete cladogenic processes a molecular cytogenetic technique (Fluorescence In Situ Hybridization, FISH) was used. We could make accurate inferences of the mechanisms that underlie chromosomal evolution. The purpose of our work was to apply a probe of the chromosome 11 of CAPp (11qHe+) obtained by chromosome microdissection to analyse the evolution of this heterochromatin by FISH. Fifteen individuals of 4 Ceboidea genera were studied by standard FISH procedures: 5 subspecies of Cebus apella and other 3 Cebus species, 1 Ateles chamek, 1 Aotus azarae and 1 Saimiri boliviensis. Different signals were obtained depending on the number of extracentromeric heterochromatic block previously characterized by C-band for each species. Signals were located in the extracentromeric heterochromatin ranging from 6 to 16 pairs in Cebus species. Two of them also showed telomeric positive signals. As no positive signals were obtained when metaphases of the other Ceboidea genera were analysed, we propose a genus-specific heterochromatin identity.