Effects of kinetin supplementation on the post-thaw motility,viability, and structural integrity of dog sperm

Oxidative stress is one of the major issues associated with cryopreservation because it causes a marked reduction in the post-thaw quality of semen. This study investigated the ability of kinetin to preserve the structural and functional integrity of dog sperm during cryopreservation. Pooled ejaculates were divided into 5 equal aliquots, diluted with buffer 2 supplemented with different concentrations of kinetin (0, 25, 50, 100, and 200 μM), and finally cryopreserved. The optimal concentration of kinetin was 50 μM based on the significantly improved (P < 0.05) motion characteristics and viability of post-thaw sperm samples. Moreover, kinetin-supplemented samples exhibited significantly higher (P < 0.05) sperm counts with the intact plasma membrane, normal acrosomes, mitochondria, and chromatin than control. The beneficial effects of kinetin were also reflected by the significant increase in the expression levels of anti-apoptotic (B-cell lymphoma, BCL2) and protamine-related genes (protamine 2, PRM2; protamine 3, PRM3), and decrease in the expression of pro-apoptotic (BCL2-associated X, BAX) and mitochondrial reactive oxygen species-modulating genes (ROS modulator 1, ROMO1) in kinetin-supplemented sperm samples than in control. The results demonstrated that supplementation of buffer 2 with 50 μM kinetin is ideal for reducing the magnitude of oxidative damage during semen cryoprocessing and improving the post-thaw quality of dog semen.     

Association study of protamine 2 (<Emphasis Type="Italic">PRM2</Emphasis>) gene polymorphism with male infertility in Chinese Han population

Protamine 2 (PRM2), an essential nuclear protein expressed in sperm, is known to be involved in the spermatogenesis. Although PRM2 defects have been reported to be involved in male infertility, studies for the relationship between male infertility and PRM2 polymorphisms are inconclusive. With the purpose to determine the association of PRM2 variant with male infertility in Chinese Han population, one single nucleotide polymorphism locus G398C in PRM2 which might play a role in semen quality was selected and the variant frequency was analyzed in 144 idiopathic infertile men (case group) and 111 proven-fertile men (control group) in the study. Three genotypes were discovered in the studied population and statistical analysis showed that the frequencies of GG and GC genotypes of PRM2 G398C were significantly different between the fertile and infertile men (P < 0.05) and GC genotype was associated with increased risk of male infertility (OR = 1.795, 95 % CI 1.070–3.013, P = 0.026). Further, the C allele distribution was significantly elevated in infertile group (OR = 1.484, 95 % CI 1.001–2.200, P = 0.049). Moreover, we discovered that sperm motility, progressive motility, sperm DNA integrity as well as nuclear maturity rate of GG genotype presented the highest values and were dramatically different with that of CC genotype (P < 0.05). Our results gave the first evidence that PRM2 G398C polymorphism was associated with the pathogenesis of male infertility and its genetic variation was in relation to semen quality in Chinese Han population.