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Constitutive heterochromatin polymorphism and NORs in Proechimys cuvieri Petter, 1978 (Rodentia, Echimyidae)

Vilna Maia^I; Alfredo Langguth^II

^IDepartamento de Genética, Universidade Federal de Pernambuco, Cidade Universitária, 50739 Recife, PE, Brasil. Send correspondence to V.M.
^IIMuseu Nacional Quinta da Boa Vista, 20942 Rio de Janeiro, RJ, Brasil

ABSTRACT

The constitutive heterochromatin variation, synaptonemal complex and nucleolar organizer regions (NORs) in Proechimys cuvieri from Rio Uatumã, Brazilian Amazonia are described. Fourteen specimens showed a diploid number of 2n-28, FN-46. Earlier reports in the literature on the karyotype of this species (2n-28, FN-50) misidentified the sex chromosomes. The karyotype is characterized by an irregular distribution of pericentromeric heterochromatin and an extensive polymorphism of C bands in pairs 4 and 11, represented by the presence or absence in boum homologues, in the homozygous and heterozygous condition, of large blocks of pericentromeric heterochromatin. The specimens showed only one chromosome pair (No. 8) with NORs, as is characteristic for the Echirnyidae.

Keywords: Heterochromatin polymorphism; NORs Proechimys cuvieri; Rodentia.

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