Chromosome characterization of bovines from Junqueira breed

Abstract

The present study aimed to establish a chromosomal characterization of the Junqueira breed of cattle in order to preserve them as local genetic resource.The study was based on 11 females and 3 males, from a farm located in the State of Minas Gerais, Brazil. The metaphases obtained, after lymphocyte cultures, were analyzed under conventional staining, C-banding, and after differentiation of replication bands using 5-bromodeoxiuridine (BrdU) treatment. The 2n=60 karyotype included 58 acrocentric autosomes and submetacentric X and Y chromosomes. C-banding resulted in positive staining in the centromeric region of all autosomes. Sex chromosomes presented no conspicuous C-band, but the whole Y exhibited a slight darker staining than the chromosome arms of the other elements in the karyotype. After BrdU incorporation, it was possible to identify the autosome pairs and the XY chromosomes, as well as each of the two X chromosomes in females. The early X showed longitudinal differentiation in positive and negative bands, while the late X was almost entirely negative stained, with a positive band in the interstitial region of its long arms. The Y chromosome displayed late replication in almos all its length, as evidenced by the pale staining. However, the telomeric region of the short arms showed a slight positive band.