Sex-specific proteins in normal chick embryo gonads and testis feminized by oestrogen treatment: a two-dimensional gel electrophoresis investigation.

Gonads dissected from 17-day-old normal chick embryos, as well as testes feminized by oestrogen treatment, were labelled in vitro with [35S]methionine and [14C]leucine. The patterns of cytosolic protein synthesis by the gonads were analysed using two-dimensional (2-D) polyacrylamide gel electrophoresis. In the feminized testis, two female-specific proteins appeared, the rate of synthesis of four testis-specific proteins was decreased, and quantitative variations of other synthesized proteins in relation to sex were detected. This altered protein synthesis indicates that the protein synthesis of the testis feminized by oestrogen treatment has in part become similar to that of a normal ovary. The synthesis of female-specific proteins in the feminized testis raises the question of their role in normal ovarian differentiation.

Analysis of the cytosolic proteins of chick embryo gonads by two-dimensional gel electrophoresis.

Gonads and mesonephros dissected from normal chick embryos, as well as a blood sample, were labelled in vitro with [35S]methionine and [14C]leucine. The patterns of cytosolic protein synthesis of the different tissues were analysed using two-dimensional (2-D) polyacrylamide gel electrophoresis. Three developmental stages, i.e. 8, 12 and 17 days of incubation, were investigated. Five sex-specific proteins were detected in the male and two in the female. In the testis, only one protein is already present at the 8-day stage. In the ovary, one protein exists since the 8-day stage, but it is also synthesized in the mesonephros. The second ovary-specific protein appeared only at the 12-day stage.

[Effect of tamoxifen on the feminization of chick embryo testis]. / Action du tamoxifène sur la féminisation du testicule embryonnaire de poulet.

The problem was approached whether the feminizing action of oestrogens or androgens on the chick embryo testes could be antagonized by anti-oestrogens or anti-androgens. 100 micrograms of either tamoxifen, cyproterone acetate or compound RU 23908 were injected into the chick embryo after 4 days of incubation and 100 micrograms of either oestradiol benzoate or diethylstilboestrol or 1 mg of either androsterone, dehydroepiandrosterone, 5 alpha-dihydrotestosterone or 5 alpha-androstanedione were given one day later. The surviving embryos were sacrificed when 14-17 days old and their gonads were examined morphologically and in some cases also histologically. Control embryos were only given oestrogens or androgens. Out of 20 surviving embryos treated with oestradiol only, 10 were genetic females and 10 strongly feminized males. After tamoxifen treatment, out of 20 embryos, 11 were females, 7 normal males and 2 slightly feminized males. Thus, tamoxifen suppressed the feminizing action of oestradiol. It antagonized also the feminizing action of diethylstilboestrol. Neither cyproterone acetate nor compound RU 23908 suppressed the feminizing action of androsterone or diethylstilboestrol. But tamoxifen interfered with the androgens, preventing the feminization of the testes. It is suggested that androgens bind to the oestrogen receptor.

[Feminization of embryonic chicken testicle by diethylstilbestrol and antagonistic action of tamoxifen]. / Féminisation du testicule embryonnaire de poulet par le diéthylstilboestrol et action antagoniste du tamoxifène.

The question was asked whether the feminization of the chick embryo testis by diethylstilboestrol involves oestrogen secretion. The left gonads of male embryos treated with diethylstilboestrol at the stage of 5 days of incubation were removed at the stage of 17 days and cultured in vitro in the presence of radiolabelled androstenedione, dehydroepiandrosterone, progesterone or sodium acetate. Radiochromatography and repeated crystallizations to constant specific activity were used to demonstrate the formation of oestrone and oestradiol. The results show that oestrogen synthesis takes place from any of the 4 precursors. The normal testis does not produce oestrogens or produces them only in small amounts. Thus, it can be concluded that diethylstilboestrol induces oestrogen synthesis in the chick embryo testis. In a second part of the work, it is shown that tamoxifen antagonizes the feminizing action of diethylstilboestrol on the testes, both at the morphological and biochemical levels.