Deletion of porcine BOLL is associated with defective acrosomes and subfertility in Yorkshire boars

Abstract

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.

A 1-bp deletion in bovine QRICH2 causes low sperm count and immotile sperm with multiple morphological abnormalities

“…These findings suggest that the 1-bp deletion does not compromise traits other than semen quality. This agrees with loss-of-function alleles in other genes with extreme testis-biased expression [8][9][10]50] and corroborates findings in humans and mice with loss-of-function alleles in QRICH2 [34], which suggest that QRICH2 is not essential for somatic development in mammals. The deviation from Hardy-Weinberg proportions (P = 0.03) of the haplotype encompassing the 1-bp deletion is likely due to either selective breeding or the inability of homozygous males to contribute to the next generation rather than to fatal consequences arising from homozygosity.…”

A 1-bp deletion in bovineQRICH2causes low sperm count and immotile sperm with multiple morphological abnormalities

“…These findings suggest that the 1-bp deletion does not compromise traits other than semen quality. This agrees with loss-offunction alleles in other genes with extreme testis-biased expression [8], [9], [10], [50], and corroborates findings in humans and mice with loss-of-function alleles in QRICH2 [34] suggesting that QRICH2 is dispensable for somatic development in mammals. The deviation of the haplotype encompassing the 1-bp deletion from Hardy-Weinberg proportions (P=0.03) is likely due to either selective breeding or the inability of homozygous males to contribute to the next generation rather than fatal consequences arising from homozygosity.…”

Immature rat testis sustained long-term development using an integrative model

“…DAZL is mainly expressed in the early stage of spermatogenesis, which promotes proliferation and differentiation of progenitor spermatogonia by heightening the translation of thousands of genes [ 27 ] and GFRα1 is a conserved marker that appears to be most restricted to undifferentiated spermatogonia, which is used to isolate and enrich undifferentiated spermatogonia [ 28 ]. BOLL, an RNA binding protein, is an evolutionarily conserved member of the deleted in azoospermia gene family, which could cause spermatogenic arrest and sperm maturation failure in many species if lack of expression [ 29 ]. CDC25A is one of the regulator genes of meiotic progression, and decreased expression of CDC25A is associated with failure of spermatogenesis and sperm retrieval [ 30 ].…”