. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 46 A. G. CARROLL AND W. R. ECKBERG O tr UJ Q. 60 40 20. 10 100 MICROMOLAR INHIBITOR FIGURE 2. Effect of calmodulin antagonists on fertilization-induced GVBD in Spisula oocytes. Oocytes were inseminated, and 1 min later they were exposed to different concentrations of calmidazolium (filled circles), chlorpromazine (open circles), W-7 (squares), or W-5 (triangles). They were examined for GVBD 20 min later. Calmodulin antagonists do not prevent ionophore activation of Spisula oocytes lonophore A23187 activation of Spisu
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 46 A. G. CARROLL AND W. R. ECKBERG O tr UJ Q. 60 40 20. 10 100 MICROMOLAR INHIBITOR FIGURE 2. Effect of calmodulin antagonists on fertilization-induced GVBD in Spisula oocytes. Oocytes were inseminated, and 1 min later they were exposed to different concentrations of calmidazolium (filled circles), chlorpromazine (open circles), W-7 (squares), or W-5 (triangles). They were examined for GVBD 20 min later. Calmodulin antagonists do not prevent ionophore activation of Spisula oocytes lonophore A23187 activation of Spisula oocytes apparently involves a different pathway than activation by KC1 or fertilization (Eckberg, 1983). Specifically, ionophore activation should result directly from initiation of a calcium ion flux. Accordingly, we tested the effects of calmodulin inhibitors on ionophore A23187-induced GVBD. Table I shows that none of the drugs inhibited ionophore-induced GVBD. A continued calcium flux is required after the calmodulin-dependent steps The timing of the effect of calmodulin antagonists and the lack of inhibition of ionophore-induced GVBD by calmodulin antagonists suggested that a continued cal- cium flux after the calmodulin-dependent step might be required for GVBD in this species. Since calcium channel blockers are known to prevent the required calcium flux and GVBD (Guerrier et al, 1981), we treated oocytes with the calcium channel blocker, verapamil. Figure 3 shows that verapamil blocks GVBD when added up to 2¥2 minutes after KC1 treatment. Therefore, the calcium channels are required for 1-2 min after the calmodulin antagonist-sensitive period. Oocytes treated with calmodulin antagonists undergo ameboid contractions without GVBD Oocytes exposed to >50 nM chlorpromazine or W-7 or to >3 nM calmidazolium often underwent violent ameboid contractions. The contractions observed included formation and retraction of pseudopod-like protrusions and often resulted in net m
Size: 1711px × 1461px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
