Demonstration of calcium uptake and release by sea urchin egg cortical endoplasmic reticulum.
The calcium indicator dye fluo-3/AM was loaded into the ER of isolated cortices of unfertilized eggs of the sea urchin Arbacia punctulata. Development of the fluorescent signal took from 8 to 40 min and usually required 1 mM ATP. The signal decreased to a minimum level within 30 s after perfusion with 1 microM InsP3 and increased within 5 min when InsP3 was replaced with 1 mM ATP. Also, the fluorescence signal was lowered rapidly by perfusion with 10 microM A23187 or 10 microM ionomycin. These findings demonstrate that the cortical ER is a site of ATP-dependent calcium sequestration and InsP3-induced calcium release. A light-induced wave of calcium release, traveling between 0.7 and 2.8 microns/s (average speed 1.4 microns/s, N = 8), was sometimes observed during time lapse recordings; it may therefore be possible to use the isolated cortex preparation to investigate the postfertilization calcium wave.
Terasaki
M
M
Marine Biological Laboratories, Woods Hole, Massachusetts.
Sardet
C
C
D000814:Aniline Compounds; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D007091:Image Processing, Computer-Assisted; D008856:Microscopy, Fluorescence; D009865:Oocytes / Q000378:metabolism* / Q000648:ultrastructure; D010784:Photomicrography; D012617:Sea Urchins; D014741:Video Recording; D014966:Xanthenes
D000814:Aniline Compounds; D014966:Xanthenes; C059715:Fluo-3; D002118:Calcium