We think these genes developed in primitive life forms in the Precambrian, more than 500 million years ago, as a way of sensing light, he explains. The fact they are linked with the system that repairs damage from ultraviolet (UV) radiation suggests they may 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 synchronise 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, he went on to explain.
They play important roles in regulating the body-clocks of many species, from corals to fruit flies, to zebra fish and mice. The proteins they produce are similar to those in humans and other mammals, though they appear to function more like those in the fruit fly, says Professor David Miller of CoECRS and JCU.
The coral cryptochrome genes were initially identified by Dr Levy and Dr Bill Leggat working with Professor Hoegh-Guldberg (UQ) on Heron Island. Prof. Miller and Dr David Hayward, of the Australian National University, were able to add information on the coral cryptochromes from a large library of coral genes that they have been compiling (so far they have catalogued about 10,000 out of an estimated 20-25,000 genes in coral), and leading circadian clock biologists from Bar-Ilan and Tel-Aviv Universities in Israel played important roles in interpreting the data.
Many of these genes developed in deep time, in the earliest phases of organised 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. The
|Contact: Dr. Bill Leggat|
ARC Centre of Excellence in Coral Reef Studies