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. 1999 Apr 27;96(9):5019–5024. doi: 10.1073/pnas.96.9.5019

Figure 2.

Figure 2

Cadmium blocks the calcium influx required for membrane retieval. (A) Cadmium inhibits endocytotic membrane retrieval. Eggs were suspended in ASW and fertilized with sperm. After 3 minutes, the eggs were incubated for 15 minutes in ASW containing the indicated concentration of cadmium and 100 μM TMR-Dex. Eggs were then washed 4 times with PKME and assayed for fluorescent dextran uptake. All data points are mean ± SD (n = 6), normalized to a zero cadmium control. (B) To determine when calcium influx is required for triggering membrane retrieval, eggs were suspended in ASW containing 100 μM TMR-Dex and fertilized. At the indicated times (black arrows) after the addition of sperm, cadmium was added to a final concentration of 500 μM, and the eggs were incubated for up to 30 minutes. Eggs were then washed 4 times with ASW and assayed for fluorescent dextran uptake. All points are mean ± SD (n = 6), normalized relative to the control. (C) Cadmium does not alter the calcium signal from whole eggs. Eggs injected with the calcium indicator calcium green dextran were fertilized at t = 1 min. At t = 2 min, cadmium in ASW was added to a final concentration of 500 μM (●; mean whole-cell fluorescence ±SD, n = 18 cells), or ASW was added as a control (○; mean ± SD, n = 11 cells).