Fertilization, embryonic development and oviductal environment: role of estrogen induced oviductal glycoprotein.

Mammalian oviduct is the physiological site for sperm capacitation, gamete fertilization and early embryonic development. The secretory cells lining the lumen of the mammalian oviduct synthesize and secrete high molecular weight glycoprotein (OGP) in response to estrogen. The protein has been shown to interact with gametes and early embryo. Several key functions have been postulated particularly its role in pre-implantation events which would have far reaching implications in assisted reproductive technology and in the development of non-hormonal contraceptive vaccine. The intention of this article is to discuss the current status of the protein and analyze how far the postulated function of OGP has been borne out by the available data.

Characterization of antibodies to chicken riboflavin carrier protein: Antigenicity of the tryptic fragments.

The antigenecity of tryptic fragments of reduced and carboxymethylated chicken riboflavin carrier protein were studied. The tryptic sites of the native riboflavin carrier protein bound to riboflavin were inaccessible. The molecular weight and the elution profile on high performance liquid chromatography (TSK 545 DEAE) were unaltered at an enzyme to substrate ratio of 1:31. However, carboxymethylated riboflavin carrier protein could be cleaved into 3 or 4 fragments at an enzyme to substrate ratio of 1:250 or 1:125. Chromatographic separation of the tryptic fragments on high pressure liquid chromatography (TSK 545 DEAE) revealed the presence of two fragments with different elution profiles but similar molecular weight 26 ±2 kDa. Only one fragment (associated with peak 2) had the ability to displace chicken riboflavin carrier protein in an homologous chicken riboflavin carrier protein radioimmunoassay. Thus, carboxymethylated ribotlavin carrier protein which does not compete with chicken riboflavin carrier protein in the radioimmunoassay, on mild trypsinization generates a fragment which interacts with chicken riboflavin carrier protein in radioimmunoassay.

Modulation of ovarian ornithine decarboxylase activity during follicular differentiation/maturation.

The role of gonadotropins and estrogen on the regulation of ovarian ornithine decarboxylase was studied during follicular differentiation/maturation. In intact immature rats follicular differentiation/maturation was initiated with sequential administration of estrogen and follicle stimulating hormone. Ornithine decarboxylase activity in response to human chorionic gonadotropin was markedly enhanced (2-fold) in rats with preovulatory antral follicles when compared to rats with non-ovulatory follicles. This increase could be attributed to the alteration in the turnover of the enzyme. Following follicle maturation the half life of the human chorionic gonadotropin stimulated ornithine decarboxylase was increased from 18 to 62 min. This increase in half life was associated with differentition of follicles. In the estrogen treated group (which does not induce follicular differentiation), the half life of the enzyme remained unaltered. The regulation of ornithine decarboxylase through the formation of protein inhibitor antizyme induced by diamino hexane, was unaltered during follicular differentiation.