A recessive sperm defect of Yorkshire boars was detected more than a decade ago. Affected boars produce ejaculates that contain spermatozoa with defective acrosomes, resulting in low fertility. The acrosome defect was mapped to porcine chromosome 15 but the causal mutation has not been identified. We re‐analyzed microarray‐derived genotypes of affected boars and confirmed that the acrosome defect maps to a 12.24 Mb segment of porcine chromosome 15. To detect the mutation causing defective acrosomes, we sequenced the genomes of two affected and three unaffected boars to an average coverage of 11‐fold. Read depth analysis revealed a 55 kb deletion that is associated with the acrosome defect. The deletion encompasses the BOLL gene encoding the boule homolog, an RNA binding protein which is an evolutionarily conserved member of the DAZ (Deleted in AZoospermia) gene family. Lack of BOLL expression causes spermatogenic arrest and sperm maturation failure in many species. Boars that carry the deletion in the homozygous state produce sperm but their acrosomes are defective, suggesting that lack of porcine BOLL compromises acrosome formation. Our findings warrant further research to investigate the role of BOLL during spermatogenesis and sperm maturation in pigs.

中文翻译：

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约克郡公猪的猪肉BOLL缺失与顶体缺陷和不育有关

十多年前发现了约克郡公猪的隐性精子缺陷。受影响的公猪会产生含有精子和顶体缺陷的射精，导致生育力下降。顶体缺陷定位于猪15号染色体，但尚未发现因果突变。我们重新分析了受感染公猪的微阵列基因型，并确认顶体缺陷定位于猪15号染色体的12.24 Mb片段。为检测导致缺陷顶体的突变，我们将两个受影响和不受影响的公猪的基因组平均测序。覆盖范围是11倍。读取深度分析显示55 kb的缺失与顶体缺陷有关。删除包括BOLL编码布尔同源物的基因，一种RNA结合蛋白，是DAZ（在精子症中已删除）基因家族的进化保守成员。缺乏BOLL表达会导致许多物种的生精停止和精子成熟失败。以纯合子状态缺失的公猪产生精子，但它们的顶体是有缺陷的，这表明缺乏猪BOLL会损害顶体的形成。我们的发现值得进一步研究，以调查BOLL在猪精子发生和精子成熟中的作用。