Mammalian sperm

Balhom, R. (1982). A model for the structure of chromatin in mammalian sperm. J. Cell. Biol. 93 298-305. 

Tanphaichitr, N., Sobhon, P., Taluppeth, N., and Chalermisarachai, P. (1978) Basic nuclear proteins in testicular cells and ejaculated spermatozoa in man. Exp. Cell Res. 117, 347-356. Palmer, D.K., O Day, K., and Margolis, R.L. (1990) The centromere specific histone CENP-A is selectively retained in discrete foci in mammalian sperm nuclei. Chromosoma 100, 32-36. 

Mammalian sperm cells metabolize D-fructose preferentially as a source of energy. Fructose is formed in cells of the seminal vesicle from D-glucose via reduction to the sugar alcohol sorbitol using NADPH, followed by oxidation of sorbitol to fructose using NAD+. The fructose concentration... 

Mitochondria are present in all eukaryotic cells that use oxygen in respiration, but the number per cell and the form and size vary.1-4 Certain tiny trypanosomes have just one mitochondrion but some oocytes have as many as 3 x 105. Mammalian cells typically contain several hundred mitochondria and liver cells5 more than 1000. Mammalian sperm cells may contain 50-75 mitochondria,6 but in some organisms only one very large helical mitochondrion, formed by the fusion of many individual mitochondria, wraps around the base of the tail. Typical mitochondria appear to be about the size of cells of E. coli. However, study of ultrathin serial sections of a single yeast cell by electron microscopy has shown that, under some growth conditions, all of the mitochondria are interconnected.7... 

In sexually reproducing organisms, mitochondria are normally inherited exclusively from the mother. Mitochondria in mammalian sperm are usually destroyed by the egg cell after fertilisation furthermore, most mitochondria are present at the base of the sperm s tail, which is... 

Lecuyer C, Dacheux JL, Hermand E ct al. Actin-binding properties and colocalization with actin during spcrmiogencsis of mammalian sperm calicin. Biol Reprod 2000 63(6) 1801-1810. 

Within an ecotoxicological perspective, mammalian methods cannot be extrapolated automatically to other species. Sperm of teleosts, for example, differs in a few very important aspects from that of mammals. Unlike mammalian sperm it is not motile on ejaculation and attains motility only on contact with water. After activation it only moves for a few minutes (for freshwater fish typically around 1 min). Furthermore it enters the egg via the micropyle rather than through an acrosomal reaction. The first minute after the start of motility is therefore crucial to its success in fertilizing an egg, and even when it is deposited on the egg s surface it still has to move fast enough in the right direction to reach the micropyle. Clearly the fertilizing ability of fish sperm is very dependent on its motility, and any pollutant that decreases this movement may be expected to affect fertilization. 

Cordelli E, Fresegna A, D Alessio A, Eleuteri P, Spano M, Pacchierotti F, Villani P (2007) ReProComet a new in vitro method to assess DNA damage in mammalian sperm. Toxicol Sci 99 545-552... 

The mechanism by which albumin (in many cases bovine serum albumin BSA) promotes capacitation in mammalian sperm is intriguing as it is believed to function during capacitation in vitro as a sink for the removal of cholesterol from the sperm plasma membrane (Go and Wolf, 1985 Langlais and Roberts, 1998 Cross, 1998). The association between cholesterol removal from the sperm plasma membrane, albumin, and capacitation was first proposed by Davis and colleagues (1980). Removal of this sterol likely accounts for the membrane fluidity changes observed during capacitation (Wolf et al., 1986). The consequence of the removal of this sterol is that the cholesterol to phospholipid ratio in the membrane decreases, and such changes in... 

The extracellular Ca and HCO," requirement for both protein tyrosine phosphorylation and capacitation represents a novel regulatory mechanism of cellular signaling since these ions have been shown to be activators of the mammalian sperm adenylyl cyclase (Hyne and Garbers, 1979 Okamura et al., 1985 Garty and Salomon,1987 Visconti et al., 1995b). Since there appears to be a relationship between Ca, HC03 , and increased adenylyl cyclase activity, experiments were designed to determine whether the action of these ions on protein tyrosine phosphorylation and capacitation involved a cAMP-mediated pathway. As previously stated, protein tyrosine phosphorylation does not occur when sperm are incu-... 

Parkkila, S., Rajaniemi, H., and Kellokumpu, S. (1993), Polarized expression ofaband 3-related protein in mammalian sperm cells. Biol. Reprod. 49 326-331. 

Sperm penetrate the zona pellucida only after completion of the acrosome reaction. A similar process occurs in nonmammalian species, where sperm must penetrate the vitelline coat. In abalone this is accomplished by release of lysin, an acrosomal protein that disperses the vitelline coat by a noncatalytic mechanism (Lewis et al., 1982 Shaw et al., 1993). In contrast, the generally accepted model for mammalian sperm penetration of the zona pellucida is the acrosin hypothesis in which proteolysis of zona pellucida matrix glycoproteins by acrosin, the acrosomal serine esterase, plays a trailblazing role in the sperm penetration process (Yanag-... 

The patch electrode voltage-clamp is the method of choice to study V, alterations (Hamill et al., 1981). However, the high resistance seals required for these studies are not readily formed on mammalian sperm due both to geometric factors as well as the low compliance of the plasma membrane (Arnoult et al., 1996b). To date, recordings of whole cell currents, as is essential for monitoring of V, have not been reported in sperm, despite the heroic efforts exerted to obtain excised patches from these cells (Espinosa et al., 1998). As an alternative, has been ex-... 

Mammalian sperm contain tyrosine kinase activities (Berruti and Martegani, 1989). In addition, the tyrosine phosphorylation of a limited array of sperm proteins is increased during capacitation (Leyton and Saling, 1989 Duncan and Fraser, 1993 Visconti et al., 1995a,b Morte et al., 1998). In general, the relevant kinase and phosphatase enzymes have not yet been identified (Morte et al., 1998). 

Firstly, mammalian sperm regulate ZP3 signal transduction by the process of ca-pacitation, such that uncapacitated sperm exhibit very low rates of spontaneous ac-rosome reaction and do not undergo ZP3-evoked secretion. Several factors contribute to signaling quiescence. 

Babcock, D. F. and Pfeiffer, D.R. (1987). Independent elevation of cytosolic [Ca ] and pH of mammalian sperm by voltage-dependent and pH-sensitive mechanisms. J.Biol.Chem. 262 15041-15047. 

Babcock, D.F., Rufo, G.A., and Lardy, H.A. (1983). Potassium-dependent increases in cytosolic pH stimulate metabolism and motility of mammalian sperm. Proc. Natl. Acad. Sci. 80 1327-1331. 

Florman, H.M., Corron, M.E., Kim, T.E., and Babcock, D.F. (1992). Activation of voltage- dependent calcium channels of mammalian sperm is required for zona pellucida-induced aerosomal exocytosis. Dev. Biol. /52 304-314. 

Gross, M.K., Toscano, D.G., and Toscano, W.A. (1987). Calmodulin-mediated adenylate cyclase from mammalian sperm. J. Biol. Chem. 26 8672-8676. 

Kopf, G.S., Woolkalis, M.J., and Gerton, G.L. (1986). Evidence for a guanine nucleotide-binding regulatory protein in invertebrate and mammalian sperm. J. Biol. Chem. 267 7327-7331. 

Meizel, S. (1984). The importance of hydrolytic enzymes to an exocytotic event, the mammalian sperm acrosome reaction, Biol. Rev, 59 125-157. 

Walensky, L.D., Roskams, A.J., Lefkowitz, R.J., Snyder, S.H., and Ronnett, G.V. (1995). Odorant receptors and desensitization proteins colocalize in mammalian sperm. Molecular Medicine 7 130-141. 

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