Ancient “Eyes” of Early Earth Are Key to Biggest Sex Event on the Planet

For years scientists have been baffled as to how hundreds of thousands of miles of coral know to spawn just after a full moon. After all, they can’t see the moonlight, so what’s going on?

Now an international of researchers say they’ve found the aphrodisiac for the biggest moonlight sex event on the planet. It’s an ancient light-sensitive gene that they say is a trigger for the annual mass spawning of coral, which occurs shortly after a full moon.

The genes, known as a cryptochromes, occur in corals, insects, fish and even in human beings. They are a primitive light-sensing pigment mechanisms which predate the evolution of eyes.

In a new paper published in the international journal Science, the team reports its discovery that the Cry2 gene, stimulated by the faint blue light of the full moon, appears to play a central role in triggering the mass coral spawning event, one of nature’s greatest marvels.

Professor Ove Hoegh-Guldberg, who leads the University of Queensland laboratory where the genes were discovered, said “This is the key to one of the central mysteries of coral reefs. We have always wondered how corals without eyes can detect moonlight and get the precise hour of the right couple of days each year to spawn.”

What allows corals to spawn simultaneously along the immense length of the Great Barrier Reef in Australia and also in other parts of the world has been a scientific mystery up until now. They suspected that the remarkable synchronization of spawning following a full moon had to somehow involve the moonlight.

“We think these genes developed in primitive life forms in the Precambrian, more than 500 million years ago, as a way of sensing light,” explains Dr Oren Levy of the ARC Centre of Excellence for Coral Reef Studies. “The fact they are linked with the system that repairs damage from ultraviolet (UV) radiation suggests they may have evolved in eyeless creatures which needed to avoid high daytime UV by living deep in the water, but still needed to sense the blue light shed by the moon to synchronize their body clocks and breeding cycles.”

“They are, in a sense, the functional forerunners of eyes,” Professor Hoegh-Guldberg said.
In humans, cryptochromes still operate as part of the circadian system that tunes us to the rhythms of our planet, though their light-sensing function appears lost to us. Whether the ancient gene has anything at all to do with human associations between the full moon and romance is still unknown, but cryptochromes do appear to play a part in our circadian rhythm.

“Many of these genes developed in deep time, in the earliest phases of organized life on the planet,” Dr Leggat says. “They were preserved for hundreds of millions of years before being inherited by corals when they developed about 240 million years ago, and are still found today in modern animals and humans. They are an indicator that corals and humans are in fact distant relatives, sharing a common ancestor way back.”

Posted by Rebecca Sato

Nature's Clock -The Rhythm of Life
http://www.dailygalaxy.com/my_weblog/2007/06/circadian_clock.html

Full Moon Link to Animal Behavior Revealed
http://www.dailygalaxy.com/my_weblog/2007/08/does-a-full-moo.html

Link:
http://www.coralcoe.org.au/news_stories/cryptochrome.html