Chen S Y, Costa V, Azevedo M, Baig M, Malmakov N, Luikart G, Erhardt G, Beja-Pereira A
Centro de Investigação em Biodiversidade e Recursos Genéticos (CIBIO), Universidade do Porto, Campus Agrário de Vairão, 4485-661 Vairão, Portugal.
J Dairy Sci. 2008 Sep;91(9):3682-6. doi: 10.3168/jds.2008-1211.
We tested the hypothesis that extensive undiscovered genetic diversity exists in important functional genes from domestic and wild cattle species (Bos spp.). We resequenced 483 bp of a key exon (exon IV) from the kappa (kappa)-casein gene (CSN3) for a panel of samples of domestic cattle from 8 countries and a close relative species, the gayal (Bos frontalis). Six single nucleotide polymorphisms were identified. Haplotype inference revealed 12 haplotypes, of which 8 were newly discovered. Among these 8 new haplotypes, 5 differed by one nonsynonymous mutation and 3 differed by one silent mutation from previously well-characterized CSN3 alleles. From those, one was shared by the gayal and Zebu, was different from CSN3*B at position Ile136Thr, and showed a close phylogenetic relationship with the banteng, gaur, and yak. The other 7 new haplotypes were detected in our panel of worldwide local cattle breeds but were absent from previously reported commercial breeds. These results support the hypothesis that genetic diversity at the coding region of CSN3 has been underestimated. This study also highlights how important it is to resequence functionally important genes in worldwide local cattle breeds, many of which are threatened by extinction or replacement by commercial breeds.
我们检验了一个假设，即家养和野生牛种（牛属）的重要功能基因中存在大量未被发现的遗传多样性。我们对来自8个国家的一组家牛样本以及一个近缘物种大额牛（Bos frontalis）的κ（kappa）-酪蛋白基因（CSN3）的一个关键外显子（外显子IV）的483 bp进行了重测序。共鉴定出6个单核苷酸多态性。单倍型推断显示有12种单倍型，其中8种是新发现的。在这8种新单倍型中，有5种与之前已充分表征的CSN3等位基因相比，因一个非同义突变而不同，3种因一个沉默突变而不同。其中，有一种大额牛和瘤牛共有，在Ile136Thr位置与CSN3*B不同，并且与爪哇野牛、印度野牛和牦牛显示出密切的系统发育关系。其他7种新单倍型在我们的全球本地牛品种样本中被检测到，但在之前报道的商业品种中不存在。这些结果支持了CSN3编码区遗传多样性被低估这一假设。这项研究还凸显了对全球本地牛品种中功能重要基因进行重测序的重要性，其中许多品种正受到灭绝或被商业品种取代的威胁。
