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The effects of a hydrogen sulfide donor and garlic derivatives on the meiotic maturation and aging of porcine oocytes
Dvořáková, Markéta ; Sedmíková, Markéta (advisor) ; Miloslava, Miloslava (referee)
Oocyte meiotic maturation is a process of a transformation of the oocyte at the germinal vesicle stage to the oocyte at the stage of second meiotic metaphase. The process called oocyte aging occurs when oocytes are exposed after the completion of meiotic maturation to the prolonged cultivation. This process is characterized by a decrease in oocyte quality. The addition of suitable compounds into the cultivation medium could improve the quality of maturing and aging oocytes. Hydrogen sulfide is a gaseous molecule that is endogenously produced and fulfills signal function in organisms. Alliin and S-allyl cysteine are garlic derivatives that exhibit many positive effects on organisms. Many of them are mediated by their ability of releasing hydrogen sulfide. We hypothesize that the quality of oocytes in the in vitro cultivation system can be improved by the addition of the hydrogen sulfide donor and garlic derivatives into the cultivation medium. The aim of the study was to evaluate the effects of hydrogen sulfide and garlic derivatives on the meiotic maturation of oocytes, the effects of hydrogen sulfide on oocyte aging and the effects of cultivation with hydrogen sulfide and garlic derivatives on early embryonic development. It was found out that hydrogen sulfide donor accelerates oocyte nuclear maturation and causes an earlier increase of MPF and MAPK activities. Hydrogen sulfide donor improves activating potential of oocytes. It was found out that endogenous hydrogen sulfide production occurs during aging of procine oocytes and that the hydrogen sulfide production decreases after first 24 hours of prolonged cultivation. The inhibitors of hydrogen sulfide releasing enzymes impaired the quality of aged oocytes. Hydrogen sulfide donor completely suppressed fragmentation of oocytes exposed to prolonged cultivation and improved the quality of aged oocytes treated simultaneously with the inhibitors of hydrogen sulfide releasing enzymes. The presence of hydrogen sulfide donor during the prolonged cultivation of oocytes improved early embryonic development after parthenogenetic activation. It was found out that whereas alliin disrupts meiotic maturation of oocytes, S-allyl cystein has not influenced this process. S-allyl cysteine accelerated the onset of embryo cleavage and reduced ROS levels in maturing and parthenogenetically activated oocytes.