Hepatitis B Virus (HBV)

Tag: Plasma Membrane

Progesterone-Induced Acrosome Reaction: DISCUSSION(8)

Progesterone and zona glycoprotein (ZP3) can induce the AR but do not exert their effects through the same receptor, as far as the receptor-mediated ions fluxes are concerned. Despite the molecular dissimilarity of progesterone and ZP3, each of them can activate at least two different types of receptors responsible for Ca2+ channels—onereactingrapidly,andthusprobablyactivateddi-rectly by the inducer, […]

Progesterone-Induced Acrosome Reaction: DISCUSSION(7)

C-262- and P-BSA-conjugates have affinity only for the native, not for the denatured progesterone receptor of human and sperm samples. Therefore, we believe that identification of the progesterone receptor is not possible with Western blots of SDS-PAGE-separated sperm protein samples (although similar results were obtained on Western blots of SDS-PAGE human sperm protein samples as […]

Progesterone-Induced Acrosome Reaction: DISCUSSION(6)

These non-viable spermatozoa remained P-BSA-FITC positive, probably due to postacrosomal cytosolic staining (see Figs. 1C and 3B). Although a slightly higher proportion of P-BSA-FITC spermatozoa was determined with the flow cytometer in comparison with the fluorescence microscopy observation, the differences were smaller than 3-6%. It should be mentioned that P-BSA-FITC-stained sperm samples were analyzed as […]

Progesterone-Induced Acrosome Reaction: DISCUSSION(5)

The damaged plasma membrane enables labeling of a cytosolic progesterone receptor at the postequatorial region of the sperm head (Figs. 1C and 3B). Only a few deteriorated cells could be detected with a combination of patchy apical labeling together with the postequatorial labeling (probably cells that deteriorated during the AR). The majority of deteriorated cells, […]

Progesterone-Induced Acrosome Reaction: DISCUSSION(4)

In this scenario the sperm uncoating process of P-BSA-FITC-negative sperm cells was still not effective. An alternative explanation for the sperm cell population that remained negative for P-BSA-FITC or for C-262/RAM-FITC staining (after 5-h capacitation period; Figs. 5 and 6) is the possibility that they lack the progesterone receptor. However, this is unlikely, since after […]

Progesterone-Induced Acrosome Reaction: DISCUSSION(3)

Thus, only a limited proportion of the sperm population in an ejaculate appears to show the progesterone receptor after prolonged incubation. Tesarik et al. also reported the presence of a selective sperm population demonstrating the progesterone receptor in humans. Protein synthesis is completely shut down during spermatogenesis, and vesicle-mediated protein transport to the plasma membrane […]

Progesterone-Induced Acrosome Reaction: DISCUSSION(2)

Immunogold labeling of P-BSA-FITC showed the exclusive localization of the gold particles on the apical plasma membrane of viable cells (Fig. 3A) and in the cytosol of deteriorated cells (Fig. 3B). Identical results were obtained by immunogold labeling of C-262/RAM-FITC. The presence of progesterone receptors in the apical plasma membrane of spermatozoa has previously been […]