Developmental Biology Cinema
DB Cinema Main Page



The Calcium Tsunami Thru Fertilizing Medaka Fish Eggs

  After work published in Gilkey, J.C., Jaffe, L.F. Ridgway, E.G., & Reynolds, G.T. (1978) A free calcium wave traverses the activating egg of the medaka, Oryzias latipes. J. Cell Biol. 76: 448-466

Background Information
A transient rise in the intracellular calcium ion concentration: (1) helps prevent more than one sperm fertilizing an egg; and (2) plays a role in "activating" a fertilized egg. In fish, frogs, sea urchins, and mammals, when sperm and egg make contact, there is a fast and a slow "block" preventing more than one sperm fertilizing an egg (polyspermy). The rapid, transient, influx of sodium ions depolarizes the egg's membrane potential establishes the fast block to polyspermy. The slower, permanent, block to polyspermy is established by the fusion of the cortical vesicles with the plasma membrane. This vesicle fusion is driven by the increase in the cytosolic calcium ions due to the release of calcium ions from the egg's endoplasmic reticulum (ER). The release of calcium ions also activates the fertilized egg to increase its cellular respiration and to begin dividing (cleavage). The wave of release of calcium ions sweeps across the egg (tsunami).

What you see in the sequences below is the calcium ion wave in transparent fish eggs (Oryzias latipes). To see the wave of release of calcium ions in eggs, they are injected with aequorin, a protein that emits light when it binds to calcium ions. In the first two sequences, the position of the micropyle (where sperm enter to fertilize an egg) is noted. In the last sequence, an unfertilized egg with aequorin is exposed to an ionophore that makes the egg permeable to calcium ions in the medium. All sequences are approximately twice as fast as they actually occur.


Click on the "thumbnail" image or the QuickTime link to watch a sequence. You need QuickTime to watch these sequences; all sequences are silent.

Get Quicktime
  Micropyle On Left

QuickTime movie (2.5 MB)

  Micropyle Facing Us

QuickTime movie (2.4 MB)

  Ionophore Initiated Calcium Waves

QuickTime movie (1.4 MB)

Large QuickTime Movies of "Calcium Tsunami" for classroom use. Coming soon!
Do you want us to notify you when these large movies are available for download? Yes
DB Cinema Main Page  
  We welcome your comments and suggestions for the Developmental Biology Cinema.

SDB Webmaster
© Society for Developmental Biology