Platelet activating factor (PAF) is a novel signaling phospholipids that in addition to platelet activation has many biological properties. The acrosome reaction, as an essential step in mammalian fertilization, can occur in response to several agents such as PAF. Therefore, the present study aimed to assess the effect of PAF on the motility and acrosome reaction of ram spermatozoa. Semen was c...

We have previously identified and cloned a human gene, D40, that is preferentially expressed in testis among normal organs, while it is widely expressed in various human tumor cell lines and primary tumors derived from different organs. In this report, we have examined the expression and localization of this protein in human testis with an antibody specific to D40 protein. In Western analyses, ...

The acrosome reaction is a regulated exocytotic process leading to a massive fusion between the outer acrosomal membrane and the cell membrane. In spite of the great amount of information available related to the acrosome reaction in several species, there is a remarkable paucity about the role of monomeric guanosine triphosphatases (GTPases) of the Rab family-well-established participants in e...

We have developed an assay for detecting the acrosome reaction in mouse sperm using chlortetracycline (CTC) as a fluorescent probe. Sperm known to be intact with nonreacted acrosomes show CTC fluorescence in the presence of Ca2+ over the anterior portion of the sperm head on the plasma membrane covering the acrosome. Sperm which have undergone the acrosome reaction do not show fluorescence on t...

Ejaculated mammalian spermatozoa must reside in the female genital tract for some time before gaining the ability to fertilize the egg. During this time, spermatozoa undergo some physiological changes that collectively are called capacitation. Capacitation of mammalian spermatozoa is a prerequisite for acrosome reaction, which is an exocytotic event occurring before fertilization. The specific ...

18 This work describes the morphology of the sperm cell of Maja brachydactyla, with emphasis on 19 localizing actin and tubulin. The spermatozoon of M. brachydactyla is similar in appearance and 20 organization to other brachyuran spermatozoa. The spermatozoon is a globular cell composed of 21 a central acrosome, which is surrounded by a thin layer of cytoplasm, and a cup-shaped nucleus 22 with...

Fertilization typically involves membrane fusion between sperm and eggs. In Drosophila, however, sperm enter eggs with membranes intact. Consequently, sperm plasma membrane breakdown (PMBD) and subsequent events of sperm activation occur in the egg cytoplasm. We previously proposed that mutations in the sneaky (snky) gene result in male sterility due to failure in PMBD. Here we support this pro...

Acrosomal exocytosis in mammalian spermatozoa is a process essential for fertilization. We report here that atrial natriuretic peptide (ANP) markedly stimulates acrosomal exocytosis of capacitated human spermatozoa. Typically, ANP exerts some of its actions via activation of the ANP receptor (ANPR-A), a particulate guanylyl cyclase-linked receptor, and subsequent formation of guanosine 3',5'-cy...

During the last phase of spermatogenesis, spermiogenesis, haploid round spermatids metamorphose towards spermatozoa. Extensive cytoplasmic reduction and chromatin remodelling together allow a dramatic decrease of cellular, notably nuclear volume. DNA packing by a nucleosome based chromatin structure is largely replaced by a protamine based one. At the cytoplasmic level among others the acrosome...

Carbohydrates are candidates for the basis of species-selective interaction of gametes during mammalian fertilization. In this study, we sought to clarify the roles of sugar residues in the species-selective, sperm-oocyte interaction in pigs and cattle. Acrosome-intact porcine and bovine sperm exhibited their strongest binding affinities for β-Gal and α-Man residues, respectively. Porcine-sperm...