KUMARESAN A.APOORVA VERMA2023-11-202023-11-202022https://krishikosh.egranth.ac.in/handle/1/5810201530Reactive oxygen species (ROS) are involved in several sperm functions, but when their levels exceed beyond physiological concentrations, leads to oxidative stress and associated alterations in sperm fertilizing potential. Recent studies suggested that ROS is the major cause of infertility in case of human being, however the consequence of oxidative stress on bovine sperm are unclear, and the alterations in the spermatozoa at the protein level due to oxidative stress is not known. In this regard, the current study aimed to explore sperm functional attributes and proteome of the oxidative stress induced spermatozoa. Freshly ejaculated spermatozoa from Deoni (Bos indicus) bulls were subjected to oxidative stress (50μM H2O2) either in the presence or absence of seminal plasma. Flow cytometric analysis revealed that oxidative stress resulted in higher (p<0.05) proportion of ROS positive spermatozoa, dead spermatozoa, altered intra-cellular calcium concentrations and lipid peroxidation status but did not have any significant effect on sperm acrosome reaction status and mitochondrial membrane potential. Global proteomic analysis detected a total of 1441 proteins in Deoni bull spermatozoa, which are involved in 70 pathways, 118 molecular functions and 141 biological processes. The major pathway in which the identified proteins were involved was metabolic process (26%) and oxidative phosphorylation (7%). In the absence of seminal plasma, a total of 1434 proteins were identified in oxidative stress induced bull spermatozoa; among dysregulated proteins, 260 were upregulated while 191 were downregulated. A total of 78 proteins were identified to be specific to oxidative stressed spermatozoa. Among the differentially expressed proteins, 27% were involved in metabolic process, 8% were involved in reactive oxygen species and 7% were involved in oxidative phosphorylation. Significant number of proteins were involved in biological process like response to oxidative stress, spermatogenesis, protein stabilization and folding, and sperm motility. In the presence of seminal plasma, a total of 1325 proteins were identified in oxidative stress induced bull spermatozoa; among dysregulated proteins, 32 were upregulated while 21 were downregulated. It is concluded that oxidative stress significantly altered the proteomic profile of bull spermatozoa and presence of seminal plasma did not have any beneficial effect on sperm oxidative stress, functional attributes and protein profile in bulls. The findings provide valuable information regarding functional and subcellular changes in sperm due to oxidative stress.EnglishThesis