Jaffe & Créton Calcium Waves

Calcium Gradients
Self-Electrophoresis
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ljaffe@MBL.edu,
rcreton@ MBL.edu
We believe that almost all kinds of transcellular and of transorganismal waves (except for sodium and chloride action potentials) are calcium waves in the sense that they are propagated by a traveling cycle which includes a local and necessary rise in cytosolic calcium.

Such waves were predicted by Tok-io Yamamoto - a man too short to serve in World War II's Japanese army - on the basis of observations of fertilizing medaka fish eggs. However, they were first seen in 1978 with the aid of the chemiluminescent calcium reporter, aequorin (Fig. 1) 
Fig 1 - A free calcium wave propagating across a sperm-activated medaka egg. Successive photographs are 10 s apart. Egg axis horizontal with sperm entry point to the left. Last frame shows the 11 illustrated wave fronts. Bar, 500 mm. (From Jaffe paper #50: Gilkey et al, J. Cell Biology. 1978)
We also believe that calcium waves are best classified by their intracellular velocities (in the fastest direction) under relatively natural circumstances. A current classification - modified from Jaffe & Créton, 1998 - is shown in Fig. 2.

 


FIG 2

 

Classes of calcium waves based upon velocity as modified from Jaffe & Créton, 1998. Note that these values are far from continuous over the more than billion fold range of known or proposed calcium wave velocities. Rather, they are restricted to relatively narrow ranges. Thus calcium action potentials - here called ultrafast waves - vary in speed by less than four-fold from 14 to 50 cm/sec in the the dozen or so cases so far collected. This is a very narrow range compared to the more familiar sodium action potentials whose speeds vary by more than a thousand fold.

ULTRAFAST WAVES are of course propagated electrically. FAST WAVES (which include the fertilization waves (f) shown in Fig. 1) are known to be reaction-diffusion waves propagated by calcium ion diffusion. SLOW WAVES (which include cleavage furrow waves) are believed to be propagated by mechanical tension. While the propagation mechanism(s) of the recently proposed ULTRASLOW WAVES are obscure.

Double click on these four main categories of calcium waves for more information. Then please do send us word of any wave speed data that we seem to be unaware of.