. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. QUERCETIN AND FERTILIZATION 69. FIGURE 11. Lytechinus pictus egg which was exposed to 4^g/ml ionophore A23187. The egg had been treated with 30 nM quercetin for 5 min, inseminated in quercetin and treated with ionophore 5 min later. A fertilization envelope (FE) has formed and sperm have detached. FIGURE 12. Surface of an ionophore-activated, quercetin-treated egg of Lytechinus pictus. Note the presence of a fertilization envelope (FE) and forming hyaline layer (HL) and the absence of cortical granules. Bar = 1977), and
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. QUERCETIN AND FERTILIZATION 69. FIGURE 11. Lytechinus pictus egg which was exposed to 4^g/ml ionophore A23187. The egg had been treated with 30 nM quercetin for 5 min, inseminated in quercetin and treated with ionophore 5 min later. A fertilization envelope (FE) has formed and sperm have detached. FIGURE 12. Surface of an ionophore-activated, quercetin-treated egg of Lytechinus pictus. Note the presence of a fertilization envelope (FE) and forming hyaline layer (HL) and the absence of cortical granules. Bar = 1977), and thus it seems likely that the drug acts by altering the activity or orga- nization of membrane proteins. The effects of quercetin on gamete fusion may be general. We have recently found that quercetin blocks fertilization in Spisula (Eckberg, 1982) and Chaetoptems (unpublished data of W. R. Eckberg, L. D. Brown and R. Pettaway). Quercetin probably acts by inhibition of membrane fusion in these species as well. Fluorescein dyes have recently been suggested to inhibit membrane fusion in sea urchins (Carroll and Levitan, 1978a; Finkel el «/., 1981) and in other forms as well (Carroll and Levitan, 1978b). Effectiveness of these anionic dyes was directly proportional to their octanol-water partition coefficients. The mechanism of action of such dyes that inhibits membrane fusion is un- known, and there is some indication that their action is different from that of quercetin. Erythrosin B but not quercetin decreased primary gamete binding and inhibited egg activation by ionophore A23187 (Carroll and Levitan, 1978a). How- ever, both drugs blocked fertilization when added as late as 20 s after insemination, and both were still effective when egg vitelline layers were disrupted, so they probably both affected gamete membrane fusion. Since quercetin did not affect primary ga- mete binding or ionophore activation of eggs, quercetin would seem to be a superior drug for inhibition of membr
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