BACKGROUND Crossover localization during meiotic recombination is mediated by the fast-evolving zinc-finger (ZnF) domain of gene PRDM9. To study its impact on dairy cattle performance, we compared its genetic variation between the relatively small Israeli (IL) Holsteins and the North American (US) Holsteins that count millions. RESULTS Initially, we analyzed the major BTA1 haplotypes present in IL Holsteins based on the 10 most telomeric SNPs of the BovineSNP50 BeadChip. Sequencing of representative haplotype carriers indicated that for all frequent haplotypes (> 6%), the variable PRDM9 ZnF array consisted of seven tandem ZnF repeats. Two rare haplotypes (frequency < 4%) carried an indicine PRDM9, whereas all others were variants of the taurine type. These two haplotypes included the minor SNP allele, which was perfectly linked with a previously described PRDM9 allele known to induce unique localization of recombination hotspots. One of them had a significant (p = 0.03) negative effect on IL sire fertility. This haplotype combined the rare minor alleles of the only SNPs with significant (p < 0.05) negative substitution effects on US sire fertility (SCR). Analysis of telomeric SNPs indicated general agreement of allele frequencies (R = 0.95) and of the substitution effects on sire fertility (SCR, R = 0.6) between the US and IL samples. Surprisingly, the alleles that had a negative impact on male fertility had the most positive substitution effects on female fertility traits (DPR, CCR and HCR). CONCLUSIONS A negative genetic correlation between male and female fertility is encoded within the BTA1 telomere. Cloning the taurine PRDM9 gene, which is the common form carried by Holsteins, we encountered the infiltration of an indicine PRDM9 variant into this population. During meiosis, in heterozygous males, the indicine PRDM9 variant may induce incompatibility of recombination hotspots and male infertility. However, this variant is associated with favorable female fertility, which would explain its survival and the general negative correlation (R = - 0.3) observed between male and female fertility in US Holsteins. Further research is needed to explain the mechanism underlying this positive effect and to devise a methodology to unlink it from the negative effect on male fertility during breeding.

中文翻译：

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金牛座-印度杂交与PRDM9对荷斯坦牛的雄性和雌性育性的位点内性冲突效应有关。

背景技术减数分裂重组期间的交叉定位是由基因PRDM9的快速进化的锌指（ZnF）结构域介导的。为了研究其对奶牛生产性能的影响，我们比较了数以百万计的相对较小的以色列（IL）荷斯坦牛和北美（美国）荷斯坦牛之间的遗传变异。结果最初，我们基于BovineSNP50 BeadChip的10个最端粒SNP，分析了IL荷斯坦牛中存在的主要BTA1单倍型。代表性单倍型携带者的测序表明，对于所有常见单倍型（> 6％），可变的PRDM9 ZnF阵列由七个串联的ZnF重复序列组成。两种罕见的单倍型（频率<4％）带有PRDM9标记，而所有其他单倍型都是牛磺酸类型的变体。这两个单倍型包括次要SNP等位基因，它与先前描述的诱导重组热点独特定位的PRDM9等位基因完美连接。其中之一对IL父亲的生育能力有显着（p = 0.03）负面影响。这种单倍型结合了仅有的SNPs的稀有次要等位基因，对美国公猪的繁殖力（SCR）具有显着的（p <0.05）负替代作用。端粒SNP的分析表明，US和IL样品之间等位基因频率（R = 0.95）和对父本育性的替代作用（SCR，R = 0.6）总体上是一致的。出人意料的是，对男性生育力有负面影响的等位基因对女性生育性状（DPR，CCR和HCR）的替代效应最大。结论BTA1端粒内编码了男性和女性生育力之间的负遗传相关性。克隆牛磺酸PRDM9基因，这是荷斯坦（Holsteins）的常见形式，我们遇到了PRDM9标记变种渗透到该种群中的情况。在减数分裂期间，在杂合子雄性中，标记PRDM9变​​体可能诱导重组热点和雄性不育的不相容性。但是，这种变异与有利的雌性生育能力有关，这可以解释其存活率以及在美国荷斯坦牛的雄性和雌性生育率之间观察到的总体负相关性（R =-0.3）。需要进一步的研究来解释这种积极作用的潜在机制，并设计出一种方法，使之与育种过程中对雄性育性的负面影响脱钩。PRDM9标记变体可能会引起重组热点与男性不育的不相容。但是，这种变异与有利的雌性生育能力有关，这可以解释其存活率以及在美国荷斯坦牛的雄性和雌性生育率之间观察到的总体负相关性（R =-0.3）。需要进一步的研究来解释这种积极作用的潜在机制，并设计出一种方法，使之与育种过程中对雄性育性的负面影响无关。PRDM9标记变体可能会引起重组热点与男性不育的不相容。但是，这种变异与有利的雌性生育能力有关，这可以解释其存活率以及在美国荷斯坦牛的雄性和雌性生育率之间观察到的总体负相关性（R =-0.3）。需要进一步的研究来解释这种积极作用的潜在机制，并设计出一种方法，使之与育种过程中对雄性育性的负面影响无关。