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When sperm of Strongylocentrotus purpuratus or Lytechinus pictus are diluted into seawater, motility is initiated; and when exposed to egg jelly, an acrosome reaction is induced. In the presence of a variety of structurally different metal chelators (0.1-1 mM EDTA, EGTA, phenanthroline, dipyridyl, cysteine, or dithiothreitol), motility initiation is delayed and the acrosome reaction is inhibited. Of the metals detected in the sperm of these two species, very low levels of Zn +2 (0.1 /~M free Zn ÷z) uniquely prevent this chelator inhibition. L. pictus sperm concentrate 65Zn+2 from seawater, and EDTA removes 50% of the accumulated ~SZn+2 by 5 min. Since both sperm motility and acrosome reactions are in part regulated by intracellular pH (pHi), the effect of chelators on the sperm pH~ was examined by using the fluorescent pH sensitive probe, 9-aminoacridine. FDTA depresses sperm pH~ in both species, and 0.1 #M free Zn +2 reverses this pH~ depression. When sperm are diluted into media that contain chelators, both NH4CI and monensin (a Na+/H + ionophore) increase the sperm pH~ and reverse the chelator inhibition of sperm motility and acrosome reactions. The results of this study are consistent with the involvement of a trace metal (probably zinc) in the p14~ regulation of sea urchin sperm and indicate a likely mechanism for the previously observed effects of chelators on sperm motility and acrosome reactions.Sea urchin spermatozoa are immotile in semen. The motility that ensues upon dilution into seawater requires an elevation of intracellular pH (pHi)' (see references 1, 2, and 3) and is accompanied by increased cAMP levels (4, 5). The acrosome reaction (induced by egg jelly) involves increases in both pHi and intracellular Ca +2 as well as movements of Na ÷ and K + (6-9).Heavy metals are also somehow involved in sea urchin sperm motility and acrosome reactions. Metal chelators at concentrations that do not alter the Ca ÷2 or Mg +2 levels in the seawater prolong the fertilizable life of sea urchin spermatozoa (10, 11,12), and a recent investigation of this phenomenon showed that this prolongation of sperm motility by J Abbreviations used in this paper: 9AA, 9-aminoacridine, a fluorescent amine; ASW, artificial seawater formulation consisting of 423 mM NaC1.9 mM KCI, 9.27 mM CaC12, 22.94 mM MgC12, 25.5 mM MgSO4, 2.15 mM NaHCO~, and 10 mM Tris; EDTA-ASW, ASW to which 1 mM EDTA was added; OCaSW, ASW without CaC12; phi, intracellular pH.THE JOURNAL OF CELL BIOLOGY • VOLUME 100JUNE 1985 1817-1824 © The Rockefeller University Press • 0021-9525]85/05/1817/08 $ 1.00 metal chelators could be partially explained by a chelator inhibition of spontaneous (non-jelly initiated) acrosome reactions (12). It was also reported that these chelators would inhibit jelly-initiated acrosome reactions in the sperm of the sea urchin, Lytechinus pictus (12). Other reports have implicated Cu +2 and/or Zn ÷2 in the regulation of sea urchin sperm respiration and motility (13-18).We have now studied this effect of chelators on both sperm...

Photochemical immobilization technology was utilized to covalently couple polymers to silicone rubber either at multiple points along a polymer backbone or at the endpoint of an amphiphilic chain. The coating variants then were tested in vitro and in vivo for improvement of desired responses compared to uncoated silicone rubber. All coating variants suppressed the adsorption of fibrinogen and immunoglobulin G, and most also inhibited fibroblast growth by 90-99%. None of the coating variants inhibited monocyte or neutrophil adhesion in vitro. However, the surfaces that supported the highest levels of monocyte adhesion also elicited the lowest secretion of pro-inflammatory cytokines. None of the materials elicited a strong inflammatory response or significantly (p< 0.05) reduced the thickness of the fibrous capsule when implanted subcutaneously in rats. Overall, the most passivating coating variant was an endpoint immobilized polypeptide that reduced protein adsorption, inhibited fibroblast growth by 90%, elicited low cytokine secretion from monocytes, and reduced fibrous encapsulation by 33%. In general, although some coating variants modified the adsorption of proteins and the behavior of leukocytes or fibroblasts in vitro, none abolished the development of a fibrous capsule in vivo.