Sperm cell membrane

The purpose of this project is to provide the theoretical and practical foundation for the improved analysis of semen in the context of rape investigations. The research has two primary objectives l) Improvement of procedures for the identification of semen and 2) Improvement of the ability to individualize semen. These objectives will be accomplished through an analysis of acid phosphatase and other proteins to determine whether the forms which are found in semen are unique to semen and whether they display genetic polymorphisms. A similar analysis will be done of the protein markers in the sperm cell membrane. 

Spermicides are relatively inexpensive and widely available over the counter in most countries. All currently used formulations contain the non-ionic detergent nonoxinol-9, usually in a dose of 70-230 mg, but the newest formulations may contain octoxynol or benzalkonium chloride (2). All chemical agents used in spermicides disrupt the sperm cell membrane and finally rupture the cell. 

FSH plays a key role in spermatogenesis it binds G-protein-coupled membrane-bound receptors on Sertoli cells and induces the Sertoli cells to proliferate during pre- and postnatal development. FSH also induces Sertoli cells to produce androgen binding protein (ABP), TGF-beta 1, MIS and other important signalling compounds. Sertoli cells also play an important role in spermiation and are the source of the seminiferous tubule fluid that provides nutrients to sperm cells as they travel from the testis to the epididymis. 

The acrosomal process of some invertebrate sperm cells is an actin cable that sometimes forms almost instantaneously by polymerization of the actin monomers and shoots out to penetrate the outer layers of the egg during fertilization (Chapter 32). The stereocilia, the "hairs" of the hair cells in the inner ear, contain bundles of actin filaments.302 Motion of the stereocilia caused by sound produces changes in the membrane potential of the cells initiating a nerve impulse. In certain lizards each hair cell contains about 75 stereocilia of lengths up to 30 pm and diameter 0.8 pm and containing more than 3000 actin filaments in a semicrystalline array. Microvilli (Fig. 1-6) contain longitudinal arrays of actin filaments. 

Fusion of the sperm membrane with that of the ovum causes a rapid depolarization of the membrane of the ovum and an influx of calcium ions.303 304 This causes an immediate block to the entrance of any other sperm cells in most species. It also causes the fusion... 

Le Claire, L. L., Ill, Roberts, T. M., and Stewart, M. (2003). A 48 kDa integral membrane phosphoprotein orchestrates the cytoskeletal dynamics that generate amoeboid cell motility in Ascaris sperm./. Cell Sci. 116,2655-2663. 

Whether rAAV distributes to sperm cells has been of significant concern because of the possibility of introducing mutations in sperm. While AAV DNA can be found in the testes of rodents, rabbits, and dogs following either hepatic arterial or IM injections, these signals appear to be localized to the testis basement membrane and the interstitial space, with no intracellular signal observed. In mice and rats, there was a dose-dependent increase of vector expression in gona-... 

A large part of the biosynthetic capacity of a plant cell is localized in plastids, which are self-replicating organelles surrounded by a doublemembrane envelope. Plastids are present in most cells of photosynthetic eukaryotes. In most angiosperms, however, sperm cells lack plastids, a fact that makes plastid inheritance solely maternal. The envelope is composed of an outer and inner membranes, which differ in their permeability, separated by a 10 to 20-nm gap. The plastids contain DNA that is concentrated in a section of the stroma, which is the background matrix of the plastid. The plastidial ribosomes are smaller that the cytoplasmic ribosomes. 

Mesozoans are all tiny organisms that have a very simple structure the body wall consists of a thin outer membrane that is dotted with large numbers of small cilia. When they beat, they provide a means of locomotion through the host animaTs body fluids. The vast bulk of the mesozoan body consists of egg and sperm cells. There are no specialized feeding organs, and nutrients and waste products pass directly across the cell wall. 

Cryoprotectants are added to the culture medium in order to protect cells. Glycerine, the first cryoprotectant to be used, was discovered in the 1940s, and it was used for the cryopreservation of bovine sperm. More recently, it has been discovered that other substances such as dimethyl sulfoxide (DMSO), saccharides," and proteins also function as cryoprotectants. However, the mechanism of the cryopreservation process in each case remains unclear. In the present study, we compared DMSO and trehalose, which are cryoprotectants of different molecular sizes that may differ in their ability to pass through the cell membrane. 

Fertilization occurs when a sperm joins to an egg by attaching to a receptor on the outer protein layer of the egg, the zona pellucida. Immediately, the egg becomes unresponsive to other sperm. The attached sperm releases enzymes that cause the egg s chromosomes to mature and also allow the sperm to fully penetrate the zona pellucida and contact the egg s cell membrane. The membranes of the sperm and egg are then fused to create a new, single cell. Male and female chromosomes join in the new cell, fuse to create a single nucleus, and organize to set the stage for cell division. ... 

To summarize, variable structural features of lysins suggest ways to attack the elucidation of the molecular mechanism of species-specific sperm-egg recognition in abalones. The invariant structural features of lysins suggest ways to explore the molecular mechanism lysin uses to destroy nonenzymatically the integrity of the VE to allow the sperm to pass through this protective envelope and contact the egg cell membrane. 

Davis, B.K., Byrne, R., and Bedigan, K, (1980). Studies on the mechanism of capacitation Albumin-mediated changes in plasma membrane lipids during in vitro incubation of rat sperm cells. Proc. Natl. Acad. Sci. USA 77 1546-1550. 

Wolf, D.E., Hagopian, S.S., and Isogima, S. (1986). Changes in sperm plasma membrane lipid diffusibility after hyperactivation during in vitro capacitation in the mouse. J. Cell Biol. 

Lin, Y Mahan, K., Lathrop, W.F., Myles, D.G., and Primakoff, P. (1994). A hyaluronidase activity of the sperm plasma membrane protein PH-20 enables sperm to penetrate the cumulus cell layer surrounding the egg. J. Cell. Biol. 725 1157-1163. 

Primakoff, P., Hyatt, H., and Tredick-Kline, J. (1987). Identification and purification of a sperm surface protein with a potential role in sperm-egg membrane fusion. J. Cell Biol. 704 141-149. 

Trimmer, J.S., Trowbridge, I.S., and Vacquier, V.D. (1985). Monoclonal antibody to a membrane glycoprotein inhibits the acrosome reaction and associated Ca and H fluxes of sea urchin sperm. Cell 40 697-703. 

The smooth flexible surface of the erythrocyte plasma membrane allows the cell to squeeze through narrow blood capillaries. Some cells have a long, slender extension of the plasma membrane, called a cilium or flagellum, which beats in a whiplike manner. This motion causes fluid to flow across the surface of an epithelium or a sperm cell to swim through the medium. The axons of many neurons are encased by multiple layers of modified plasma membrane called the myelin sheath. This membranous structure is elaborated by... 

Teratogens are chemical species that canse birth defects. These usually arise from damage to embryonic or fetal cells. However, mntations in germ cells (egg or sperm cells) may canse birth defects, snch as Down s syndrome. The biochemical mechanisms of teratogenesis are varied. These include enzyme inhibition by xenobiotics deprivation of the fetus of essential substrates, such as vitamins interference with energy supply or alteration of the permeability of the placental membrane. 

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