Action différentielle de l'oestradiol sur les activités de la fucosyltransférase et de la galactosyltransférase de l'oviducte du triton pleurodèle

Abstract

The effects of estradiol upon the fucosyltransferase and the galactosyltransferase activities in the oviduct of Pleurodeles waltlii Michah. were determined. The total activity of the enzymes contained in an oviduct (determined in the presence of exogenous monosaccharide acceptors which were prepared from the products which are normally elaborated in this reaction) is markedly increased by the hormonal treatment. However, if we compare this increase with the concomitant rise in the protein content of the enzymic extract, two phases can be distinguished: Prior to the ninth day of treatment, the specific activity (total activity per milligram of protein) of the fucosyltransferase is not affected while the specific activity of the galactosyltransferase is slightly increased. After the ninth day of treatment, the specific activity of the galactosyltransferase is constant while the specific activity of the fucosyltransferase is very much increased. In the same period, the endogenous activity of the fucosyltransferase is also very much increased; this means that fucose acceptors are accumulated in the cells. These results are discussed in the light of previous findings concerning the chemical composition of the egg jelly coat which consists of glycoproteins normally synthesized in the presence of these enzymes. The differential effect of estradiol upon the two transferases is interpreted as being important in the chemical differentiation of this egg jelly coat and its physiological significance is discussed.