Assessment of variations in Indian Bubalus bubalis seminal plasma proteins during winter and summer seasons

 The Indian riverine buffaloes are more susceptible to variations in the environment. These variations affect seminal plasma proteins, which in turn affect fertility. This study was conducted to evaluate variations in the Indian Bubalus bubalis seminal plasma protein profile using two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) during winter and summer seasons, and its relation with sperm motility and viability. The nine ejaculates from three animals were from winter season while the other nine ejaculates from the same animals were from summer season. The semen samples collected from all bulls in both seasons have similar characteristics of mass activity and total concentration. However, sperm viability was significantly higher in winter season. The 2D-PAGE pattern displayed 42, 29 and 28 protein spots during winter season while 44, 29 and 29 spots during summer season for the first, second and third bull, respectively. Ultra high performance liquid chromatography-mass spectrometry (UPLC-MS) was performed to identify expressed protein spots in winter and summer seasons. During both seasons, four commonly expressed protein spots B6 (pI 8.5, Mr 122.54 kDa), B7 (pI 9.7, Mr 89.98 kDa), B9 (pI 9.3, Mr 19.72 kDa) and B10 (pI 9.7, Mr 16.80 kDa) were identified as glucose phosphate isomerase, epididymal secretory protein E1, peroxiredoxin 5 precursor and tubulin polymerization-promoting protein, respectively. These proteins are involved in either the mechanism of sperm maturation or structural formation. In addition, B37W (pI 6.0, Mr 32.88 kDa), B48W (pI 8.2, Mr 80.14 kDa), B59W (pI 5.6, Mr 90.37 kDa) and B61W (pI 5.8, Mr 15.34 kDa) were differentially expressed protein spots in winter season only. Spots B37W, B48W, B59W, B61W, B6, B7, B9 and B10 were identified as phosphoglycerate kinase LOC538592, androgen regulated protein, hypothetical protein LOC514663, sorbitol dehydrogenase, glucose phosphate isomerase, epididymal secretory protein E1, peroxiredoxin 5 precursor and tubulin polymerization-promoting protein family member. These proteins are known to have modulating properties on sperm motility and viability and also to provide high energy source to sperm. The better fertilizing ability of bull during winter season can be due to the differentially expressed proteins.