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Published on: July 6, 2009
Enhancing Cryopreserved Sperm Quality and Fertility of Buffalo Through Protein L-Isoaspartyl Methyltransferase
D S Kumar Wodeyar1, S K Bhure2, Karikalan M1
1ICAR - Indian Veterinary Research Institute, Izatnagar, India.
Background:
Spermatozoa undergo protein modifications due to oxidative stress as a result of freezing-thawing. With increasing information on oxidatively modified proteins of frozen-thawed spermatozoa, it is essential to investigate the effect of supplementing the semen extender with the repair enzyme protein L-isoaspartyl methyltransferase (PIMT) on the quality of frozen-thawed spermatozoa.
Objectives:
To investigate the expression of PIMT in male reproductive organs, including semen, and to evaluate the effect of recombinant PIMT (rPIMT) supplementation on the quality of frozen-thawed spermatozoa.
Materials And Methods:
Expression of PIMT was studied using immunofluorescence assays, PCR, and Western blotting. Functionalities of spermatozoa were studied by HOST, viability, progressive motility, acrosome intactness, and zona-binding assays.
Results:
The PIMT was detected all along the male reproductive tract, including spermatozoa, but could not be detected in the seminal plasma. The rPIMT was added to the extender at 0.5 (Group II), 1.0 (Group III), and 2.0 µg/80 million spermatozoa (Group IV), with the control (Group I) receiving no rPIMT. A significant effect was observed in Group IV, with an 8.9% increase in progressive motility, a 13.0% increase in viability, an 11.9% increase in HOST response, and an 11.8% improvement in acrosome integrity compared with the control. Further, motility and kinematic parameters (VCL, VAP, DSL, VSL, DAP, ALH, and BCF) of frozen-thawed spermatozoa were assessed using CASA. Most motion parameters were higher in group IV compared with the I, II, and III groups. Additionally, the in vitro fertilizability of Group IV spermatozoa was approximately 2.32 times higher compared with the control group.
Discussion And Conclusion:
The better functional attributes and a fold increase in fertilizability of frozen-thawed spermatozoa positively correlate with the quality of spermatozoa. It may be presumed that the rPIMT improved the cryopreserved semen quality through the repair of oxidatively damaged seminal plasma proteins.
