Seeing is believing: Calcium waves and development

Hokusai, “The Great Wave” from the series Thirty-six Views Mount Fuji, 1830

Parthenogenesis - when an ovum develops in the absence of fertilization - was a phenomenon well studied in the mid- and late-1800's by German physiologist, Jacques Loeb. His efforts on this subject provided key insights into the very fundamental events that occur during fertilization, however, he never came to know what mechanism(s) actually initiated egg development. From his work, Loeb found that ions were important for egg activation but it was later work from several groups in the 1950’s to early 1970’s that identified calcium as the particular ion of importance. At the time, no method for measuring free calcium within living cells existed and so the findings from these experiments were interpretable in different ways. It wasn’t until after the discovery of the jellyfish bioluminescent protein, Aequorin, and the more widespread use of photomultiplier tubes within labs, that the first calcium wave was observed immediately after fertilization. The findings from this work were important in identifying calcium’s vital role in the earliest stage of development and in demonstrating the diverse and polymodal roles that calcium plays in biology.

• 1977 - First observed calcium wave PNAS
• 1978 - Characterization of calcium wave JCB