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Dr.Hiron M Harshan wins the State Young scientist award

Dr.Hiron M Harshan, Assistant Professor, Department of Animal Reproduction, College of Veterinary and Animal Sciences of Kerala Veterinary and Animal Sciences University, Mannuthy, Thrissur received the Young Scientist award at the 23rd Kerala Science Congress 2011 held at Thiruvananthapuram for his research on identification of PDC-109 like protein(s) as the factor promoting sperm cryodamage.

Dr.Hiron graduated from College of Veterinary and Animal Sciences, Mannuthy during 2002 and did Post graduation and PhD from Indian Veterinary Research Institute. He had received several awards which includes Dr.Renchi P George memorial award, ISSAR Young scientist and Endowment award 2006 and 2009. He had 17 research articles to his credit which include five international articles in peer reviewed journals.

The research findings on identification of PDC-109 like protein(s) as the factor will have wide applications and ramifications in the area of cryopreservation and conservation. At a time when we are looking for conservation of endangered species these findings can be used to modify the existing freezing protocols of different mammalian species that will in turn improve the viability of fertile spermatozoa after cryopreservation.

The Vice Chancellor KVASU congratulated Dr Hiron Harshan and urged him to continue his research projects ahead.

Abstract

IDENTIFICATION OF PDC-109 LIKE PROTEIN(S) AS THE FACTOR PROMOTING SPERM CRYODAMAGE

Hiron M. Harshan, Surya Sankar and L. P. Singh

The major protein fraction of the seminal plasma of most mammalian species is constituted by the Fibronectin type 2 (FN-2) family proteins. The FN-2 proteins play a crucial role in fertilization, including prevention of premature capacitation, induction of sperm capacitation in the female genital tract and formation of oviductal sperm reservoirs. PDC-109 forms the predominant fraction of the FN-2 family. A major physiological function of FN-2 proteins, and thus PDC-109, is their ability to bring about sperm cholesterol efflux. Cholesterol efflux is known to destabilize the sperm plasma membrane. We hypothesized that the destabilized spermatozoa would be more prone to cryodamage, hence PDC-109 would be promoting sperm cryodamage. The objective of this study was to test the veracity of this hypothesis. The study was conducted using cauda epididymal spermatozoa as they are virtually free of PDC-109. There had been no previous studies identifying the presence of PDC-109 like protein(s) in buffalo seminal plasma hence another objective of the study was to identify the protein in buffalo semen. Antisera raised against PDC-109, isolated and purified from cattle seminal plasma was utilized to detect the presence of PDC-109 like proteins in buffalo seminal plasma by western blotting. Indirect immunofluorescent labeling of spermatozoa located the presence of proteins in a higher concentration at the acrosome and mid-piece region of ejaculated spermatozoa. The proteins were absent on cauda epididymal spermatozoa, indicating that the protein in buffaloes may be synthesized in parts of the male reproductive tract later than epididymis. Immunohistochemistry revealed the presence of PDC-109 like proteins in the lumen of buffalo seminal vesicle indicating its synthesis in the tissue. Cryopreservation studies were carried out with cauda epididymal spermatozoa as they were the ideal candidates for studying the effect of the proteins. Tris based extenders of cauda epididymal semen were supplemented with varying doses of PDC-109. Treatment of spermatozoa with varying levels of PDC-109 resulted in considerable sperm damage after cryopreservation and a reduction in sperm characteristics such as motility, hypo-osmotic stress response, bovine cervical mucus penetration distance, acrosome reaction and binding of spermatozoa to homologous ova. The damage was found to be dose dependent with the higher doses of protein bringing about increased damage. It was further observed that the protective action of eggyolk during cryopreservation might be to some extent due to its ability to chelate the Fn-2 proteins. The study revealed that the PDC-109 like protein(s) have negative effects in the context of sperm storage. The study also identified the presence, location and the probable source of PDC-109 like protein(s) in buffalo semen. The findings of the study can be utilized to modify existing freezing protocols of different mammals so as to improve the harvest of viable and fertile spermatozoa after cryopreservation and thus aid in conservation of endangered species or employed for commercial interests.