Carlini E, Palmerini C A, Cosmi E V, Arienti G
Istituto di Biochimica e Chimica Medica, Perugia, Italy.
Arch Biochem Biophys. 1997 Jul 1;343(1):6-12. doi: 10.1006/abbi.1997.9999.
Prostasomes are membranous vesicles (150-200 nm diameter) present in human semen. They are secreted by the prostate gland and contain large amounts of cholesterol, sphingomyelin, and Ca2+. In addition, some of their proteins are enzymes. Prostasomes enhance the motility of ejaculated sperm and are involved in a number of biological functions. In this work, we study the fusion of prostasomes to sperm by determining the relief of octadecylrhodamine self-quenching and the fluidity of membranes by measuring the fluorescence anisotropy of diphenylhexatriene. We present the following findings: (a) the contact of sperm cells with prostasomes at slightly acidic pH causes the fusion of the membranes; (b) the amount of transferred lipid depends on the prostasome/sperm ratio; (c) the fluidity of sperm is much higher than that of prostasomes; (d) the fusion changes some properties of sperm cells, such as fluidity, which decreases greatly; and (e) the extent of fluidity variations depends on the prostasome to sperm ratio. We propose that the H(+)-dependent fusion of prostasomes to sperm may have physiological consequences. In fact, this process can modify the lipid and protein pattern of sperm plasma membranes.
前列腺小体是存在于人类精液中的膜性小泡（直径150 - 200纳米）。它们由前列腺分泌，含有大量胆固醇、鞘磷脂和Ca2+。此外，它们的一些蛋白质是酶。前列腺小体可增强射出精子的活力，并参与多种生物学功能。在这项研究中，我们通过测定十八烷基罗丹明自猝灭的解除情况来研究前列腺小体与精子的融合，并通过测量二苯基己三烯的荧光各向异性来研究膜的流动性。我们得出以下发现：（a）在略酸性pH条件下，精子细胞与前列腺小体的接触会导致膜融合；（b）转移的脂质数量取决于前列腺小体/精子的比例；（c）精子的流动性远高于前列腺小体；（d）融合改变了精子细胞的一些特性，如流动性，其大幅降低；（e）流动性变化的程度取决于前列腺小体与精子的比例。我们认为前列腺小体与精子的H(+)依赖性融合可能具有生理意义。事实上，这个过程可以改变精子质膜的脂质和蛋白质模式。
