Sulfate and glucosamine labelling of the intercellular matrix in vitellogenic follicels of a moth

Summary InHyalophora cecropia the intercellular spaces of the follicles contain during vitellogenesis a matrix that can be labelled eitherin situ or in culture with³⁵S-sulfate and³H-glucosamine. The matrix was demonstrated by autoradiography and also by treating follicles for 15 min with pronase, which released TCA-soluble matrix fragments with molecular weights of up to 2×10⁶ daltons. Testicular hyaluronidase degraded the high molecular weight fragments, and thus it is probable that they are chondroitin sulfate-like mucopolysaccharides. With the termination of vitellogenesis new matrix is no longer deposited, and the pre-existing material is disassembled. The sulfated matrix may account for the patency of the intercellular diffusion channels essential for blood protein uptake and also for the low level, extracellular binding of blood proteins that characterizes the vitellogenic follicle inHyalophora.     

Effect of sulfur and nitrogen nutrition on derepression of ferredoxin-sulfite reductase in leek seedlings

The ferredoxin-sulfite reductase (Fd-SiR; hydrogen-sulfide: ferredoxin oxidoreductase, EC 1.8.7.1) activities of shoot and root of leek (Allium tuberosum) were increased by sulfate limitation in the early stage of growth. Western blot analysis demonstrated an increased amount of SiRs in root under sulfate limitation, suggesting that SiRs were derepressed. The derepression was observed in shoot when 1.5 mM nitrate was supplied to the plants under sulfate limitation, and clearly in root when 15 mM nitrate was supplied under sulfate limitation. When nitrate was absent from the nutrient solution, the SiR activity in both tissues was very low. Combined with the results of the sulfate- or nitrate-limitation experiments, it is suggested that the degree of the derepression of SiR in both tissue under sulfate limitation is affected by the concentration of nitrate, and further that the mechanism of regulation of the SiR activity is different in each tissue. The decreases in the ratios of the total SiR activities (shoot/root) in the latter stage of seedling growth indicate that root play a very important role in sulfate assimilation.     

The effects of dehydroepiandrosterone (DHEA) and its metabolites on the polycystic ovarian condition (PCO): cystogenic changes of rat granulosa cells in vitro

During mammalian folliculogenesis, granulosa cells (GCs) are initially steroidogenically quiescent, later proliferate, and subsequently commence to hormonally differentiate, first producing estrogen and later, in the preovulatory stage, secreting both estrogen and progesterone. In this study and elsewhere, we have used follicle-stimulating hormone with a combination of growth factors in vitro to simulate the above in vivo conditions. In a previous study, we used dehydroepiandrosterone (DHEA) to accomplish the polycystic ovary condition (PCO) in rats. In the latter model, there were high circulating levels of DHEA and its metabolite, androstenedione. In the present study, we investigated the effects of high levels of DHEA (10⁻⁵M) and its metabolites, androstenedione, androstenediol and dehydroepiandrosterone sulfate on the quiescent, proliferative, and steroidogenically differentiating stages of GCs cultured in a serum-free medium for up to 10 days. In addition to possessing the regularly occurring organelles, when cultured with the aforementioned androgens, the GCs acquired endoplasmic reticulum of the smooth variety which is associated with steroidogenesis. The radioimmunoassay data showed that GCs cultured in the quiescent and proliferative stages in the presence of the androgens, no longer remain in these stages but proceed to differentiate in a preovulatory direction by producing both estrogen and progesterone. This study supports our hypothesis that high circulating levels of DHEA and/or its metabolites have most effect during the quiescent and proliferative stages of granulosa cells, with regard to their structure and their steroidogenic activities.