Sperm interaction

Implicated in regulating cell-cell interactions and cell migration during oogenesis May function as recognition markers for mediating egg-sperm interaction May protect the embryo from osmotic lysis, artificial activation, mechanical destruction, and bacterial infection by retaining Ca + around the embryo (KDN-gp has affinity for Ca + ions) 0-Acetylation and KDN cosylation render polySia chains resistant to depolymerization by siali-dases consequence unknown (protective )... 

Both attractive forces and repulsive forces are included in van der Waals interactions. The attractive forces are due primarily to instantaneous dipole-induced dipole interactions that arise because of fluctuations in the electron charge distributions of adjacent nonbonded atoms. Individual van der Waals interactions are weak ones (with stabilization energies of 4.0 to 1.2 kj/mol), but many such interactions occur in a typical protein, and, by sheer force of numbers, they can represent a significant contribution to the stability of a protein. Peter Privalov and George Makhatadze have shown that, for pancreatic ribonuclease A, hen egg white lysozyme, horse heart cytochrome c, and sperm whale myoglobin, van der Waals interactions between tightly packed groups in the interior of the protein are a major contribution to protein stability. 

Cell attachment-recognition site Various proteins involved in cell-cell (eg, sperm-oocyte), virus-cell, bacterium-cell, and hormone-cell interactions... 

Leyton, L., LeGuen, P Bunch, D., and Saling, P. M. (1992). Regulation of mouse gamete interaction by a sperm tyrosine kinase. Proc. Nad. Acad. Sci. USA 59 11692-11695. 

For the last forty years, many reports have emerged on the hormone-like effects of chemical compounds such as pesticides and industrial chemicals upon wildlife and humans. The effects of these materials are believed to be either direct or indirect. Direct effects involve positive or negative interactions with the hormone receptors. Indirect effects may result when the synthesis of hormones or their receptors is altered, or the transport, metabolism, or elimination of hormones is modified in some way. The discovery of hormone-like properties of some compounds was made long after their release into the environment. It was shown soon after their introduction that aviation crop dusters handling DDT had low sperm counts and workers at a plant producing the insecticide kepone were reported to have low libido, sperm counts and to be impotent. Subsequently, experiments conducted in laboratory animals demonstrated unambiguously the oestrogenic activity of these pesticides. 9 refs. 

An alternative efficient approach to disperse CNTs relies on the use of synthetic peptides. Peptides were designed to coat and solubilise the CNTs by exploiting a noncovalent interaction between the hydrophobic face of amphiphilic helical peptides and the graphitic surface of CNTs (Dieckmann et al., 2003 Zoibas et al., 2004 Dalton et al., 2004 Arnold et al., 2005). Peptides showed also selective affinity for CNTs and therefore may provide them with specifically labelled chemical handles (Wang et al., 2003). Other biomolecules, such as Gum Arabic (GA) (Bandyopadhyaya et al., 2002), salmon sperm DNA, chondroitin sulphate sodium salt and chitosan (Zhang et al., 2004 Moulton et al., 2005), were selected as surfactants to disperse CNTs (Scheme 2.1). 

Topical spermicides such as nonoxynol-9 (N9) and benzalkonium chloride act on sperm membranes through a detergent effect, namely, hydrophobe-hydrophobe interaction between the active and substrate (spermatozoa). The idea was to optimize the cationic/hydrophobic polymer in the drug delivery system so epithelial cells were protected without sacrificing the drug s spermicidal activity. One of the questions that needed to be answered in designing an optimum cationic/hydrophobe modified polymer was the effect of the hydrophobe on the drug activity (N9 initially, and other actives subsequently). 

Interaction with the cervical mucus has been anticipated to be highest with cationic species [58], such as benzalkonium chloride, chlorhexidene, and vantocil (polyhexamethylene biguanide). A clear exception is the water-soluble sulfated polystyrene derivative (ORE 13904) [23]. In general, sperm penetration is lower for water-soluble cationic polymers than for anionic or nonionic polymers [59]. 

Eggert-Kruse, W., Kohler, A., Rohr, G., and Runnebaum, B. The pH as an important determinant of sperm-mncns interaction. Fertility and Sterility 1993, 59(3), 617-628. 

Sonicated and denatured salmon sperm DNA (or other anionic maCTomolecules) may be used to reduce nonspecific probe interaction and electrostatic forces. The latter also may be reduced with dextran sulfate. High-stringency (low-sodium) hybridization ensures that complete complementarity will characterize the probe-target hybrid. 

NaF was not mutagenic in bacterial assays. Although fluoride has been shown to be clas-togenic in a variety of cell types, the mechanism of clastogenicity has been attributed to the effect of fluoride on the synthesis of proteins involved in DNA synthesis and/or repair, rather than direct interaction between fluoride and DNA. In general, there was no effect on sperm morphology or the frequency of chromosomal aberrations, micronuclei, sister chromatid exchange, or DNA strand breaks in rodents treated in vivo. ... 

Sperm evaluations routinely include data on sperm number, morphology and motility (Berman etal., 1996). Testicular spermatid count or cauda epididymal weight are other useful measures of sperm production, but no surrogate measures are adequate to evaluate sperm morphology or motility. A number of other indices of sperm function have been employed (e.g., sperm-zona interactions, acrosome reaction, sperm swelling studies), but these have been of limited utility and infrequently used and have not been incorporated into any testing guidelines. 

WHO (1999) WHO laboratory manual for the examination of human semen and sperm-cervical mucus interaction, 4th ed. Cambridge, Cambridge University Press, and Geneva, World Health Organization. 

Four spin-labelled derivatives of sperm whale metmyoglobin were prepared by site-directed mutagenesis.101 Cyanide anion or imidazole was added to prepare low-spin Fe(III). Iron relaxation rates were measured by saturation recovery or inversion recovery between 5 and 17 K and by analysis of the temperature-dependent contribution to the CW line widths of the iron signal at 20 to 160 K. The nitroxyl 7i values in spin-labelled Zn-substituted myoglobin were measured to provide values in the absence of interaction with the more rapidly-relaxing Fe(III). The full shapes of the nitroxyl saturation-recovery curves for the spin-... 

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