STUDIES OF THE INFLUENCE OF A SPECIFIC 97 -KD PORCINE OVIDUCTAL SECRETORY PROTEIN ON THE DE-NOVO SYNTHESIS OF PREIMPLANTATION EMBRYOS

Embryo development following supplementation of media with 97-kd ovidu ctal secretion protein was investigated in comparison to cultivation i n NCSU-23, modified NCSU-23 (without BSA) and modified NCSU-23 + ovidu ctal secretion (day 1) by assessing embryonic protein synthesis. The s pecific protein was isolated from cannulated oviductal fluid by means of Wheat Germ Agglutinin (WGA) Affinity Chromatography. In vivo develo ped zygotes (Z) and 2-cell-stage embryos were cultured in various medi a. After cultivation to 4-cell-stage embryos and blastocysts, 5 embryo s per group were labelled (4 h) in 50-mu l drops of modified NCSU-23 c ontaining 1 mCi/ml of [S-35]-methionine (> 1000 Ci/mM), subsequently r insed with nonradioactive medium and placed in 60 mu l SDS-lysis buffe r. The same counts per minutes (cpm) of each embryonic stage were used for 1-D electrophoresis (Tris/Glycine buffer system). Gels were pretr eated with fluorite, dried, and exposed to Hyperfilm MP at -70 degrees C. The rate for incorporation of radiolabelled methionine into protei n was different according to developmental stages, as well as accordin g to culture conditions. 4-cell embryos responded less to the media su pplements than blastocysts. Oviductal secretions (experiment 1) and 97 -kd protein application increased the rate of incorporation of methion ine into blastocysts in comparison with the control groups (NCSU-23, m odified NCSU-23). The lowest incorporation was detected after cultivat ion without BSA. Qualitative changes in protein profiles depended on d evelopmental stage and were not influenced by culture conditions. The results indicate that the development of pig zygotes to 4-cell stage e mbryos is less influenced by the culture condition, because of storage of maternal information in such embryonic stages. Development to blas tocysts needs the activation of the embryonic genome and places great demands on the metabolism of embryos. The culture conditions have an i nfluence on this development. Specific proteins (oviductal secretion, 97-kd oviductal protein) stimulate the incorporation of methionine mor e strongly than non-specific proteins (BSA). The absence of proteins i n the culture media inhibited the development of blastocysts. Obviousl y, the incorporation of methionine rather than the pattern of de novo synthesized proteins is primarily influenced.