Banded karyotype of Nelore cattle (Bos taurus indicus Linnaeus, 1758)

Abstract

Chromosome banding techniques were applied and standardized to obtain karyotype characteristics for the first time in Brazil of Nelore cattle - Bos taurus indicus Linnaeus, 1758 - (bovine subspecies most prominent in Brazilian livestock). Blood samples were collected from the animals of the School of Agrarian and Biological Sciences of the Pontifical Catholic University of Goiás, two males and two females of pure breed. These samples were submitted to the cell culture method to study metaphase chromosomes. Chromosome banding techniques (C, G and NOR) revealed the karyotype architecture of Nelore cattle common with that of other breeds of zebu cattle formerly karyotyped. The diploid chromosome number was invariably normal, 2n = 60. C-banding revealed C-positive heterochromatin in centromeric regions almost in all chromosomes. G-banding presented the expected band pattern in the respective chromosome pairs in correspondence with the established chromosomal patterns for the species. Ag-staining for nucleolus organizer regions (AgNOR) was identified on the telomeric end of the long arm in 7 autosomal chromosomes. In this study we found more regions in chromosomes with staining than presented in the literature for the Bos indicus group (BIN). These NOR regions were repeated on the same chromosomes for the 4 animals studied.

Keywords: AgNOR; Brazil breeds; Cytogenetics; Karyotype; Zebu.

Figure 1.

C-banded bovine chromosomes of Nelore breed. A female (XX) B male (XY).

Figure 2.

GTG-banding profile for the pairing of the chromosomes of the Nelore karyotype. A female (XX) B male (XY).

Figure 3.

The nucleolus organizer regions on the long arm of the pairs of autosomal chromosomes 2, 3, 4, 11, 22, 25, and 28 by NOR-banding technique in female and male respectively. A female (XX) B male (XY).