Genes of hypothalamic-pituitary-gonadal axis play a key role in male reproductive performance. This study evaluated the polymorphisms of luteinizing hormone receptor (LHR) and hypothalamic gonadotropin-releasing hormone (GnRH) genes and their effects on sperm quality traits including semen volume per ejaculate (VOL), sperm density (SD), fresh sperm motility (FSM), thawed sperm motility (TSM), acrosome integrity rate (AIR), and abnormal sperm rate (ASR) collected from 205 Chinese Hostein bulls. The study bulls consisted of 205 mature Chinese Holstein, 27 Simmental, 28 Charolais, and 14 German yellow cattle. One single nucleotide polymorphism (SNP) (A883G) in exon 2 of GnRH and two SNPs (A51703G and G51656T) in intron 9 of LHR were identified in 274 bulls. Analysis of variance in 205 Chinese Holstein bulls showed that age had significant effect on both SD and FSM (P < 0.01), and ASR (P < 0.05). With regards to genotype and its interaction with age, only the SNP of G51656T in LHR gene had significant effect on SD (P < 0.05, P < 0.01; respectively). The association result showed that bulls with AG genotype had higher FSM than bulls with AA and GG genotype in LHR at 51,703 locus (P < 0.10), and bulls with GG genotype had higher SD than bulls with TT genotype in LHR at G51656T locus (P < 0.10). Phenotypic correlation among the traits revealed that significant negative correlations were observed between ASR and AIR (r = -0.736, P < 0.01), ASR and AIR (r = -0.500, P < 0.01). There were moderate positive correlations between VOL and SD (r = 0.422, P < 0.01), as well as FSM (r = 0.411, P < 0.01). In conclusion, LHR may be a potential marker for sperm quality of SD and FSM.

ABSTRACT. Bone morphogenetic protein 15 (BMP-15) expression has been detected in the testis, but its roles in this organ has not been well elucidated. We evaluated polymorphisms of the BMP-15 gene by PCR-SSCP and PCR-RFLP in 212 Chinese Holstein bulls, and investigated possible associations with sperm quality traits, including semen volume per ejaculate, sperm density, fresh sperm motility, thawed sperm motility, acrosome integrity rate, and abnormal sperm rate. A single nucleotide polymorphism (C5697T) in intron 1 of the BMP-15 gene was identified in these bulls. Age was found to have significant effects on both fresh sperm motility and abnormal sperm rate. A significant effect of genotype on fresh sperm motility was also observed. Least square analysis showed that CT genotype bulls had significantly lower fresh sperm motility than CC or TT genotype bulls. In conclusion, BMP-15 should be considered as a potential genetic marker for sperm quality, based on its association with fresh sperm motility.

Polymorphisms of the methylenetetrahydrofolate reductase (MTHFR) gene are associated with abortion, early embryo loss and recurrent spontaneous abortion in human. However, information on the association between MTHFR polymorphism and cow abortion is scarce. In the present study, the effects of MTHFR polymorphism on cow abortion were investigated. The PCR-SSCP and DNA sequencing were applied to detect the polymorphisms in exon 4 and 7 of MTHFR gene in a total of 569 Chinese Holstein cattles. The homocysteine levels during various periods of pregnancy were detected by HPLC. The results show that 8137C/T SNP was identified in exon 7 of MTHFR, but no polymorphism was detected in exon 4. Association analysis revealed that the 8137C/T mutation was significantly associated with cow abortion (P = 0.0002). Regarding relative risk of incidence, cows with CT genotype showed greater relative risk than those with CC (OR = 2.05, 95% CI = 1.40 to 3.00). The blood homocysteine levels of individuals with CT genotype were significantly higher than those with CC genotype during the first 6 months of pregnancy and in non-pregnant cows (P < 0.05). In conclusion, MTHFR may be a beneficial candidate gene to control cow abortion.

ABSTRACT. Spermatogenesis, is a complex process of precisely regulated intracellular events, where it is affected by many factors. Long-distance transport of animals is one of the stressors that may influence spermatogenesis and sperm quality. The present study chose luteinizing hormone receptor (LHR), androgen receptor (AR), and heatshock protein 70 (HSP70) as our target genes to investigate their mRNA and protein expression in the testes of long-distance transported (about 1000 km) mice. Histological analysis showed that there was a reduction in the thickness of the seminiferous epithelium in the transported mice, and a significant decrease in body weight and sperm count in the epididymis was also observed. mRNA expression was determined by QPCR in the testis of transported and control mice. The levels for AR decreased significantly in transported mice. LHR and HSP70 expression in the testes of the transported mice was slightly higher than that of control mice but did not reach a significant level. A similar tendency of protein expression was also observed by Western blot analysis. The levels of LHR and HSP70 increased slightly after transportation. However, none of the changes were statistically significant compared with the control mice. In conclusion, long-distance transport has an adverse effect on reproductive organs and spermatozoa in adult mice.