ANALYSIS OF CONSTITUTIVE HETEROCHROMATIN BY FLUOROCHROMES AND IN-SITUDIGESTION WITH RESTRICTION ENZYMES IN SPECIES OF THE GROUP CALLITHRIXARGENTATA (CALLITRICHIDAE, PRIMATES)

The karyotypes of the species belonging to the group Callithrix argent ata (Callitrichidae, Platyrrhini) are characterized by large amounts o f distal constitutive heterochromatin (CH). The CH of the species C. a rgentata, C. humeralifera and C. emiliae was analyzed by banding with the restriction enzymes Hinfl, MboI, AluI, RsaI, DdeI, HaeIII and MspI , as well as the fluorochromes CMA(3) and DAPI. The results obtained p ermitted us to classify the CH of these species into three distinct ty pes: 1) distal CH with a homogeneous response to enzymatic action, whi ch was unchanged (HinfI, MboI, AluI, HaeIII), partially digested (DdeI ) or fully digested (RsaI), being CMA(3)+, DAPI-; 2) centromeric CH, g enerally presenting a reduced band size. The varying extent of reducti on, ranging from none to total, and also the variation of fluorochrome staining indicates that there is heterogeneity in this type of CH; 3) CH of the distal portion of the X chromosome of C. argentata and of t he Y chromosome was CMA(3)- and unchanged by the enzymes, except for R saI, which caused a reduction in size. MspI was the only enzyme unable to induce bands. Sequential C-banding permitted us to perceive bandin g variations that could not be observed simply by RE banding.