Search results for "Acrosome"
showing 10 items of 17 documents
Exosomes in semen: opportunities as a new tool in prostate cancer diagnosis
2017
Abstract: Prostate cancer (PCa) is the most common cancer in men. Nowadays, it is diagnosed through the test of serum prostate-specific antigen (PSA) and rectal examination; however, there is still debate about the PSA-based diagnosis. Seminal fluid (SF), contains a high concentration of subcellular lipid-bound microparticles, traditionally termed "prostasomes", that are extracellular vesicles (EVs) released into the extracellular space by prostate gland's epithelial cells. These vesicles, first described in 1982 promote motility of sperm cells, regulation of sperm cell capacitation, acrosome reaction and immune suppression within the female reproductive tract. It was demonstrated that pros…
Extracellular Vesicles in Human Reproduction in Health and Disease.
2017
Extensive evidence suggests that the release of membrane-enclosed compartments, more commonly known as extracellular vesicles (EVs), is a potent newly identified mechanism of cell-to-cell communication both in normal physiology and in pathological conditions. This review presents evidence about the formation and release of different EVs, their definitive markers and cargo content in reproductive physiological processes, and their capacity to convey information between cells through the transfer of functional protein and genetic information to alter phenotype and function of recipient cells associated with reproductive biology. In the male reproductive tract, epididymosomes and prostasomes p…
Limited proteolysis by acrosin affects sperm-binding and mechanical resilience of the mouse zona pellucida.
2021
Abstract The encounter of oocyte and sperm is the key event initiating embryonic development in mammals. Crucial functions of this existential interaction are determined by proteolytic enzymes, such as acrosin, carried in the sperm head acrosome, and ovastacin, stored in the oocyte cortical granules. Ovastacin is released upon fertilisation to cleave the zona pellucida, a glycoprotein matrix surrounding the oocyte. This limited proteolysis hardens the oocyte envelope, and thereby provides a definitive block against polyspermy and protects the developing embryo. On the other hand, acrosin, the renowned and most abundant acrosomal protease, has been thought to enable sperm to penetrate the oo…
Sperm activation and sperm-egg interaction
2006
Different steps of sperm activation such as acrosomal reaction and capacitation are described in details. The molecules involved in sperm-egg interaction are also reported.
Mating systems and protein–protein interactions determine evolutionary rates of primate sperm proteins
2013
To assess the relative impact of functional constraint and post-mating sexual selection on sequence evolution of reproductive proteins, we examined 169 primate sperm proteins. In order to recognize potential genome-wide trends, we additionally analysed a sample of altogether 318 non-reproductive (brain and postsynaptic) proteins. Based on cDNAs of eight primate species (Anthropoidea), we observed that pre-mating sperm proteins engaged in sperm composition and assembly show significantly lower incidence of site-specific positive selection and overall lower non-synonymous to synonymous substitution rates ( d N / d S ) across sites as compared with post-mating sperm proteins involved in capac…
Interference of antisperm antibodies with the induction of the acrosome reaction by zona pellucida (ZP) and its relationship with the inhibition of Z…
1997
Abstract Objective: To determine whether antisperm antibodies can interfere with the induction of the acrosome reaction (AR) by the zona pellucida (ZP) and whether this interference also can occur in the absence of an inhibitory effect on ZP binding. Design: Prospective in vitro study. Setting: A tertiary care center, the Andrologic Clinic, University of L'Aquila. Patient(s): Sera from 12 infertile patients with high titers of circulating antibodies directed against the sperm head were studied. Intervention: None Main Outcome Measure(s): The effect of antisperm antibodies on ZP binding was evaluated by matching antibody-exposed and nonexposed donor sperm suspensions labeled with fluorescein…
A novel pyruvate kinase (PK-S) from boar spermatozoa is localized at the fibrous sheath and the acrosome
2007
Boar spermatozoa contain a novel pyruvate kinase (PK-S) that is tightly bound at the acrosome of the sperm head and at the fibrous sheath in the principal piece of the flagellum, while the midpiece contains a soluble pyruvate kinase (PK). PK-S could not be solubilized by detergents, but by trypsin with no loss of activity. Purified PK-S as well as PK-S still bound to cell structures and soluble sperm PK have all kinetics similar to those of rabbit muscle PK-M1. The PK-S subunit had a relative molecular mass of 64 ± 1 × 103(n= 3), i.e. slightly higher than that of PK-M1, and carried an N-terminal extension (NH2-TSEAM-COOH) that is lacking in native PK-M1. Evidence is provided that PK-S is en…
Regulatory properties of 6-phosphofructokinase and control of glycolysis in boar spermatozoa.
2007
Glycolysis is crucial for sperm functions (motility and fertilization), but how this pathway is regulated in spermatozoa is not clear. This prompted to study the location and the regulatory properties of 6-phosphofructokinase (PFK, EC 2.7.1.11), the most important element for control of glycolytic flux. Unlike some other glycolytic enzymes, PFK showed no tight binding to sperm structures. It could readily be extracted from ejaculated boar spermatozoa by sonication and was then chromatographically purified. At physiological pH, the enzyme was allosterically inhibited by near-physiological concentrations of its co-substrate ATP, which induced co-operativity, i.e. reduced the affinity for the …
Expression and compartmentalisation of the glycolytic enzymes GAPDH and pyruvate kinase in boar spermatogenesis
2008
Boar spermatozoa contain isoforms of both glyceraldehyde 3-phosphate dehydrogenase (GAPDH, EC 1.2.1.12) and pyruvate kinase (PK, EC 2.7.1.40). The sperm-specific forms, GAPDH-S and PK-S, are tightly bound to cell structures. By immunofluorescence microscopy GAPDH-S and PK-S were localised in the principal piece of the boar sperm flagellum as well as in the acrosomal region of the sperm head and at the head–midpiece junction. The midpiece of the flagellum, however, contains isoforms of GAPDH and PK that were only recognised by antibodies against somatic GAPDH and PK, respectively, but not by the antibodies against GAPDH-S and PK-S. In sections of boar testis, GAPDH-S and PK-S were first dete…
Computer assisted sperm morphometry in mammals: a review.
2014
Computer-assisted sperm morphometry analysis (CASMA or ASMA) systems were developed to reduce the subjectivity of sperm morphology assessement. This review focuses on a complete description of the CASMA technique, including recent developments, factors of variation, results in the different species and possible applications. Techniques to study sperm morphometry include light microscopy, phase-contrast microscopy and, more recently, fluorescence microscopy. Most published studies on sperm morphometry have been centered on the whole sperm heads, although some of them also measured other parts of the sperm structure, such as the nucleus, acrosome, midpiece or flagellum. The independent study …