Study On The Chromosomal Karyotype Of Alpacas

Blood samples from 23 Huacaya alpacas ,3 males and 20 females ,were used to study chromosome karyotype ,so as to provide some effective cytogenetics basis for the selectioiymprovement by crossing and disease diagnosis of alpacas ,and genetic mechanisms of sex determination. Peripheral blood lymphocyte culture was used to prepare chromosome. Methods of trypsase-EDTA and BSG (Barium hydroxide / Saline / Giemsa)were used for G-banding and C-banding respectively . The results showed as follows:Firstly , the number of diploid chromosomes was in the alpacas 2n=74,with the karyotype 74, XY and 74, XX for males and females respectively. Thirty six homologous pairs of chromosomes were autosomes , in which chromosomes ,pairs of 1 to 20 were acrocentric-subterminal , 21 to 36 metacentric-submetacentric . And X chromosome was metacentric, Y chromosome terminal.Secondly , observation to C-bands indicated that positive bands distributed in the centromeres of all chromosomes ,id. all centromeres of chromosomes were densely dyed , but two arms lightly dyed .Thirdly , the analysis of G-bands showed that bright and dark bands appeared by turn. It showed different bands. And every pair of chromosomes had its distinct band ,and the longer the chromosomes, the more the . number of bands, and the more clear the bands.Additionally, several types of chromosome aberrations were observed in somatic cells of the normal alpacas .These aberrations involved triploid, tetraploid and ring chromosomes . But their aberration frequencies were very low.