Meiotic Recombination Differences in Rams from Three Breeds of Sheep in the US

This study used a cytogenetic approach to quantify and compare the number of COs per spermatocyte in rams from 3 breeds of sheep: Suffolk, Icelandic, and Targhee. In total, 2,758 spermatocytes and over 170,000 COs were examined. Suffolk rams exhibited the lowest mean number of COs (61.1 ± 0.15) compared to Icelandic (63.5 ± 0.27) and Targhee (65.9 ± 0.26) rams. Significant differences in the number of COs per spermatocyte were observed between Suffolk, Icelandic, and Targhee breeds as well as within each breed. Additionally, the number and location of COs were characterized for homologous chromosomes in a subset of spermatocytes for each ram. A positive correlation was identified between the number of COs and the length of the homologous chromosome pair. Suffolk and Icelandic rams exhibited up to 7 COs per chromosome, while Targhee rams exhibited up to 9. Further, distinct CO location preferences on homologous chromosome pairs with 1, 2, 3, and 4 COs were observed in all 3 breeds. These data in sheep will aid in elucidating the mechanism of mammalian meiotic recombination, an important contributor to genetic diversity.Cytogenet Genome Res
Source: Cytogenetic and Genome Research - Category: Genetics & Stem Cells Source Type: research