Biosciences Research Division, Department of Primary Industries Victoria, 5 Ring Rd, Bundoora 3086, Australia.
Genet Sel Evol. 2013 Jul 16;45(1):25. doi: 10.1186/1297-9686-45-25.
Identification of the processes and mutations responsible for the large genetic variation in milk production among dairy cattle has proved challenging. One approach is to identify a biological process potentially involved in milk production and to determine the genetic influence of all the genes included in the process or pathway. Angiogenin encoded by angiogenin, ribonuclease, RNase A family 5 (RNASE5) is relatively abundant in milk, and has been shown to regulate protein synthesis and act as a growth factor in epithelial cells in vitro. However, little is known about the role of angiogenin in the mammary gland or if the polymorphisms present in the bovine RNASE5 gene are associated with lactation and milk production traits in dairy cattle. Given the high economic value of increased protein in milk, we have tested the hypothesis that RNASE5 or genes in the RNASE5 pathway are associated with milk production traits. First, we constructed a "RNASE5 pathway" based on upstream and downstream interacting genes reported in the literature. We then tested SNP in close proximity to the genes of this pathway for association with milk production traits in a large dairy cattle dataset.
The constructed RNASE5 pathway consisted of 11 genes. Association analysis between SNP in 1 Mb regions surrounding these genes and milk production traits revealed that more SNP than expected by chance were associated with milk protein percent (P < 0.05 significance). There was no significant association with other traits such as milk fat content or fertility.
These results support a role for the RNASE5 pathway in milk production, specifically milk protein percent, and indicate that polymorphisms in or near these genes explain a proportion of the variation for this trait. This method provides a novel way of understanding the underlying biology of lactation with implications for milk production and can be applied to any pathway or gene set to test whether they are responsible for the variation of complex traits.
鉴定导致奶牛产奶量存在大量遗传变异的过程和突变一直具有挑战性。一种方法是鉴定一个可能参与产奶过程的生物学过程，并确定该过程或途径中包含的所有基因的遗传影响。血管生成素由血管生成素、核糖核酸酶、RNASE5 家族 5（RNASE5）编码，在牛奶中相对丰富，已被证明可调节蛋白质合成，并在体外作为上皮细胞的生长因子发挥作用。然而，人们对血管生成素在乳腺中的作用知之甚少，也不知道牛 RNASE5 基因中存在的多态性是否与奶牛的泌乳和产奶性状有关。鉴于牛奶中蛋白质含量增加具有很高的经济价值，我们检验了这样一个假设，即 RNASE5 或 RNASE5 途径中的基因与产奶性状有关。首先，我们根据文献中报道的上下游相互作用的基因构建了一个“RNASE5 途径”。然后，我们在一个大型奶牛数据集上测试了该途径基因附近的 SNP 与产奶性状的关联。
构建的 RNASE5 途径包含 11 个基因。这些基因周围 1Mb 区域内 SNP 与产奶性状的关联分析表明，与产奶性状相关的 SNP 比预期的随机 SNP 多（P < 0.05 显著水平）。与其他性状（如乳脂含量或繁殖力）没有显著关联。
这些结果支持 RNASE5 途径在产奶，特别是乳蛋白百分比中的作用，并表明这些基因内或附近的多态性解释了该性状变异的一部分。这种方法为理解泌乳的基础生物学提供了一种新方法，对产奶量有影响，并可应用于任何途径或基因集，以检验它们是否是复杂性状变异的原因。
