102PEROXIREDOXINS (PRDX 1-6) EXPRESSION PATTERN IN IMMATURE, MATURED OOCYTES AND VARIOUS STAGES OF IN VITRO FERTILIZED AND PARTHENOGENETICALLY ACTIVATED PREIMPLANTATION OVINE EMBRYOSThe present study investigated the expression pattern of panel of genes related to antioxidant protection response in both immature and matured oocytes and at various stages of preimplantation ovine embryos produced by In vitro fertilization (IVF) and parthenogenetic activation (PA) against three standard reference genes (GAPDH, YWHAZ, SDHA) using quantitative real time polymerase chain reaction (qRT-PCR). All the six isoforms of peroxiredoxins(PRDXs) were expressed in immature oocytes and except PRDX 4 and 6 theremaining PRDX 1, 2, 3 and5 were expressed in mature oocytes. Significant differences were observed between IVF and PA embryos at 2 and 4-cell stages of embryos in expression pattern of PRDX 1, 2, 3 and 5. Except PRDX 4, all the isoforms of PRDX were observed in morula stage and not much difference was observed between IVF and PA groups of embryos. It could be inferred that the expression pattern of PRDX depended on the stress generated in the specific localization of particular gene. The expression of PRDX 1 and 2 showed almost a similar pattern since the localization of PRDX 1 and 2 were in cytosol. The absence of PRDX 4 and 6 transcripts in 2 and 4-cell stage embryos might be due to least importance of particular isoforms localized in plasma membrane. The mitochondrial localization of PRDX 3 and 5 transcripts were more in IVF than PA embryos at morula stage thus reflecting more effective antioxidant regulation in IVF embryos than PA embryos. To the best of our knowledge this is the first work on the peroxiredoxins(PRDXs 1-6) expression in ovine oocytes and embryosargoraja@gmail.comResearch462014Ovine,Embryos,In vitro fertilization,Parthenogenetic activation,Peroxiredoxins, Quantitative real time PCRRaja Sengodan,Balasubramanian Sivasankaran,Dhinakarraj Gopal,Veerapandian ChitravelanResearch Scholar,Tamil Nadu veterinary and Animal Sciences University, Chennai, India 600051,Research Scholar,Tamil Nadu veterinary and Animal Sciences University, Chennai, India 600051,Professor and Head Department of Animal Biotechnology, MVC, Chennai, India 600007., Dean Veterinary College and Research Institute, Thanjavur, India 614625.