Animal Genomics Lab, Animal Biotechnology Centre, National Dairy Research Institute, Karnal, India.
J Anim Sci Biotechnol. 2013 Apr 4;4(1):15. doi: 10.1186/2049-1891-4-15.
The Y chromosome in mammal is paternally inherited and harbors genes related to male fertility and spermatogenesis. The unique intra-chromosomal recombination pattern of Y chromosome and morphological difference of this chromosome between Bos taurus and Bos indicus make it an ideal model for studying structural variation, especially in crossbred (Bos taurus × Bos indicus) bulls. Copy Number Variation (CNV) is a type of genomic structural variation that gives information complementary to SNP data. The purpose of this study was to find out copy number differences of four Y chromosomal spermatogenesis-related candidate genes in genomic DNA of crossbred and purebred Indicine bulls.
Four Y chromosomal candidate genes of spermatogenesis namely, sex determining gene on Y chromosome (SRY), DEAD box polypeptide 3-Y chromosome (DDX3Y), Ubiquitin specific peptidase 9, Y-linked (USP9Y), testis-specific protein on Y chromosome (TSPY) were evaluated. Absolute copy numbers of Y chromosomal genes were determined by standard curve-based quantitative real time PCR. Copy numbers of SRY and TSPY genes per unit amount of genomic DNA are higher in crossbred than Indicine bulls. However, no difference was observed in DDX3Y and USP9Y gene copy numbers between two groups.
The present study demonstrates that the structural organization of Y chromosomes differs between crossbred and Indicine bulls which are reproductively healthy as observed from analysis of semen attributes. The absolute copy numbers of SRY and TSPY genes in unit mass of genomic DNA of crossbred bulls are significantly higher than Indicine bulls. No alteration in absolute copies of DDX3Y and USP9Y gene was found between the genome of crossbred and Indicine bulls. This study suggests that the DDX3Y and USP9Y are likely to be single copy genes in the genome of crossbred and Indicine bulls and variation in Y chromosome length between crossbred and Indicine bulls may be due to the copy number variation of SRY gene and TSPY array.
哺乳动物的 Y 染色体是父系遗传的，携带有与男性生育力和精子发生相关的基因。Y 染色体独特的染色体内重组模式和牛和瘤牛之间这种染色体的形态差异，使它成为研究结构变异的理想模型，特别是在杂交（牛×瘤牛）公牛中。拷贝数变异（CNV）是一种基因组结构变异，提供了与 SNP 数据互补的信息。本研究旨在确定杂交和纯种种 Indicine 公牛基因组 DNA 中四个与精子发生相关的 Y 染色体候选基因的拷贝数差异。
评估了四个与精子发生相关的 Y 染色体候选基因，即 Y 染色体性别决定基因（SRY）、Y 染色体 DEAD 盒多肽 3（DDX3Y）、Y 染色体泛素特异性肽酶 9（USP9Y）、Y 染色体睾丸特异性蛋白（TSPY）。通过基于标准曲线的实时定量 PCR 确定 Y 染色体基因的绝对拷贝数。与 Indicine 公牛相比，杂交公牛的单位基因组 DNA 中 SRY 和 TSPY 基因的拷贝数更高。然而，两组之间 DDX3Y 和 USP9Y 基因拷贝数没有差异。
本研究表明，Y 染色体的结构组织在繁殖健康的杂交和 Indicine 公牛之间存在差异，这可以从精液属性的分析中观察到。杂交公牛单位质量基因组 DNA 中 SRY 和 TSPY 基因的绝对拷贝数明显高于 Indicine 公牛。在杂交和 Indicine 公牛的基因组中，未发现 DDX3Y 和 USP9Y 基因的绝对拷贝数发生改变。本研究表明，DDX3Y 和 USP9Y 可能是杂交和 Indicine 公牛基因组中的单拷贝基因，杂交和 Indicine 公牛之间 Y 染色体长度的差异可能是由于 SRY 基因和 TSPY 基因座的拷贝数变异。
