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J. Biotec. Biodivers. v. 5, N.2: pp. 140-147 May 2014

except in the W sex chromosome, which is totally heterochromatic. Type I classification includes mammals, fish and ants and Type II includes amphibians, grasshoppers and plants. Type I is characterized by constitutive heterochromatin presence in the region pericentromeric, while Type II is characterized by interstitial or terminal CBG-banding. The location data of constitutive heterochromatin in birds show pericentromeric and interstitial CBG-

banding, thus birds may be classified in both groups (I or II). Constitutive heterochromatin can be observed in pericentromeric region of Ramphocelu scarbo (Correia et al. 2009), Tangara cayana and Tachyphonus rufus (Correia et al. 2009), while in Pheucticus aureoventris it was observed pericentromeric and interstitial CBG-banding (Ledesma et al. 2006).

Figure 3 – Sequential analysis by conventional Giemsa and CBG-banding staining of metaphase from Mimus saturninus : (a) conventional Giemsa staining; (b) CBG-banding showing positive staining in the pericentromeric region of macrochromosomes, microchromosomes and in the Z sex chromosome. Note that the W sex chromosome it was totally heterochromatic. Arrows show the sex chromosomes Z and W.

The silver staining revealed one pair of microchromosome bearing NORs. This microchromosome pair has a secondary constriction below the centromere (Fig. 4). Because of the presence of secondary

constrictions, Lucca and Rocha (1992) inferred that the species Mimus saturninus could have macro and microchromosomes involved in the organization of the nucleolus, which was not confirmed in ours Ag-NORs results.