Analysis of constitutive heterochromatin by fluorochromes and in situ digestion with restriction enzymes in species of the group Callithrix argentata (Callitrichidae, Primates).

The karyotypes of the species belonging to the group Callithrix argentata (Callitrichidae, Platyrrhini) are characterized by large amounts of distal constitutive heterocharomatin (CH). The CH of the species C. argentata, C. humeralifera and C. emiliae was analyzed by banding with the restriction enzymes HinfI, MboI, aluI, RsaI, DdeI, HaeIII and MspI, as well as the fluorochromes CMA3 and DAPI. The results obtained permitted us to classify the CH of these species into three distinct types: 1) distal CH with a homogeneous response to enzymatic action, which was unchanged (HinfI, MboI, AluI, HaeIII), partially digested (DdeI) or fully digested (RsaI), being CMA3+, DAPI-; 2) centromeric CH, generally presenting a reduced band size. The varying extent of reduction, 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 the Y chromosome was CMA3- and unchanged by the enzymes, except for RsaI, which caused a reduction in size. MspI was the only enzyme unable to induce bands. Sequential C-banding permitted us to perceive banding variations that could not be observed simply by RE banding.