Gene disruption experiments have proven that the acrosomal protein IZUMO1 is essential for sperm-egg fusion in the mouse. However, despite its predicted function, it is not expressed on the surface of ejaculated spermatozoa. Here, we report the dynamics of diffusion of IZUMO1 from the acrosomal membrane to the sperm surface at the time of the acrosome reaction, visualized using a fluorescent pr...

The acrosome reaction is a unique type of regulated exocytosis. The single secretory granule of the sperm fuses at multiple points with the overlying plasma membrane. In the past few years we have characterized several aspects of this process using streptolysin O-permeabilized human spermatozoa. Here we show that Rab3A triggers acrosomal exocytosis in the virtual absence of calcium in the cytos...

Proteins of the presynaptic exocytic machinery have been found associated with the acrosome of male germ cells, suggesting that the sperm acrosome reaction and neurotransmission at chemical synapses may share some common mechanisms. To substantiate this hypothesis, we studied the expression and ultrastructural localization of prominent pre- and postsynaptic protein components in rat testis. The...

BACKGROUND Fertilization in mammals comprises the sequential interactions of the sperm with the cumulus oophorus, zona pellucida, and oocyte plasma membrane. Here we investigate proteasome activity in human sperm and its possible involvement during the fertilization process. METHODS Proteasome activity was measured in intact sperm and in sperm extracts using the fluorogenic substrate Suc-Leu-...

The season may affect the values of fresh semen variables and therefore influence the success of cryopreservation. The aim of this study was to improve the evaluation of seasonal changes in semen quality in Spanish Black Castellana roosters maintained under natural environmental conditions. Semen was collected from 11 Black Castellana roosters (housed under natural photoperiod and temperature c...

acrosome vesiculate, releasing the acrosomal contents (Austin & Bishop, 1958; Austin, 1963; Hadek, 1963; Piko & Tyler, 1964; Barros, Bedford, Franklin & Austin, 1967; Bedford, 1967b). The inner acrosome membrane then becomes the outer ensheathment of the sperm head. Under these circumstances, the contents of the compartment between the inner acrosome membrane and the nucleus may be important fo...

Cryopreservation protocols induce partially irreversible damage to mammalian sperm plasma membranes. Previous studies have indicated that adding cholesterol to the plasma membrane, as cholesterol-loaded-cyclodextrins, improves cryosurvival of sperm. Therefore, the purpose of this study was to determine if treating sperm of Markhoz bucks with cholesterol-loaded-cyclodextrins (CLC) (0, 0.75, 1.5,...

BACKGROUND Spermatogenesis is a complex cellular developmental process which involves diverse families of genes. The Xlr (X-linked, lymphocyte regulated) family includes multiple members, only a few of which have reported functions in meiosis, post-meiotic maturation, and fertilization of germ cells. Slx-like1 (Slxl1) is a member of the Xlr family, whose expression and function in spermatogenes...

Ninety ejaculates from a total of 76 AI boars were extended in Beltsville Thawing Solution (BTS). Boar identity, breed, weight of the ejaculate and sperm concentration were registered. Motility and acrosome integrity were assessed after storage at 16-18 degrees C for 6, 30, 54, 78, and 102 h. Storage time had a significant influence on both motility (p < 0.01) and acrosome integrity (p < 0.001)...

Oestrogens and 1α,25(OH)2-vitamin D3 (1,25-D3) are steroids that can provide effects by binding to their receptors localised in the cytoplasm and in the nucleus or the plasma membrane respectively inducing genomic and non-genomic effects. As confirmed notably by invalidation of the genes, coding for their receptors as tested with mice with in vivo and in vitro treatments, oestrogens and 1,25-D3...