. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. POLYSPERMY BLOCKS 291 9 UJ a. c O CD CO \ SBTI \ \ \ \ •v. Seconds After Insemination Figure 11. Effect of SBTI on sperm binding and detachment during fertilization in Strongylocentrolus purpuratus. Eggs were inseminated in sea water (• •) or 1 mg/ml SBTI (• •), and the number of sperm bound per egg was determined at indicated times after insemination. Sperm rapidly bind to the egg surfaces and then begin to detach as the cortical reaction propagates around the surface of the eggs (compare with Fig. 2, above). This process i
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. POLYSPERMY BLOCKS 291 9 UJ a. c O CD CO \ SBTI \ \ \ \ •v. Seconds After Insemination Figure 11. Effect of SBTI on sperm binding and detachment during fertilization in Strongylocentrolus purpuratus. Eggs were inseminated in sea water (• •) or 1 mg/ml SBTI (• •), and the number of sperm bound per egg was determined at indicated times after insemination. Sperm rapidly bind to the egg surfaces and then begin to detach as the cortical reaction propagates around the surface of the eggs (compare with Fig. 2, above). This process is completed in control eggs within 50 s. SBTI-treated eggs do not show the normal detachment phase. From Vacquier et al. (1973), reprinted with permission of Academic Press. 1978; Yoshida and Aketa, 1978). This process tends to reduce the probability of polyspermy. Detachment of the vitelline layer and destruction of sperm receptors in sea urchins may be promoted by two distinct SBTI-sensitive proteases that are secreted by the cortical granules (Carroll and Epel, 1975; Carroll, 1976; Carroll et 1982). Similar phenomena apparently operate in mammalian eggs where the secretion of a "trypsin-like" cortical granule protease has been implicated in altering the zona pel- lucida to prevent polyspermy (Gwatkin et al., 1973; Bleil et al., 1981; Wolf 1981). Peroxide mediated block Phagocytic leukocytes employ peroxidatic reactions involving secreted myelo- peroxidase and H2O2 to kill bacteria and other microorganisms (Klebanoff, 1980). The peroxidatic system activated in sea urchin eggs at fertilization, secreted ovope- roxidase and H2O2 which promotes cross-linking of the fertilization envelope, was. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Marine Biological Laboratory (Woods Hole, Ma
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