Protein synthesis during maturation of bovine oocytes, effect of epidermalgrowth factor

The objective of this study was to determine whether epidermal growth facto r (EGF) affected protein synthesis in oocytes during maturation. Initially, the effect of EGF on oocyte maturation was examined to ensure that there w as a beneficial effect of EGF in the protein-free maturation medium used in these studies. Results showed that the presence of EGF during maturation s ignificantly enhanced cleavage rate and development to the blastocyst stage . Development after maturation in the presence of EGF was similar to that s een in medium containing serum, luteinizing hormone, follicle-stimulating h ormone and estradiol. Protein synthesis was examined in immature oocytes an d after 16 or 24 h maturation. Oocytes from each group were labelled by inc ubation for 4 h with S-35-methionine, the proteins were then separated by t wo-dimensional sodium dodecyl sulphate-polyacrylamide gel electrophoresis. Between 400 and 500 proteins could be separated using this method and marke d changes in protein synthesis was observed during maturation. Changes in e ight different proteins were observed when protein patterns from oocytes ma tured for 16 h with and without EGF were compared. These results suggest th at EGF plays a physiological role in oocyte maturation and identification o f the proteins induced by EGF could be important for improving our understa nding of oocyte maturation in vitro.