Prize won for light shed on biological clocks

Issue 51

21 October - 3 November 1997

Staff Newspaper of Imperial College of Science, Technology and Medicine

Prize won for light shed on biological clocks

Dr Russell Foster at the symposium on biological rhythm in Sapporo, northern Japan.

Dr Russell Foster, recently promoted to reader in the Department of Biology, has been awarded the 1997 Honma Prize for his research in the area of circadian rhythms (biological clocks).

"It's absolutely superb," commented Dr Foster, who moved to Imperial College in 1995 as a governors' lecturer. "The Honma award is the premier international prize in my field of research and comes with a substantial cash award."

The Honma foundation of Life Science funds the prize and a biannual symposium on biological clocks, held in Sapporo, northern Japan, which Dr Foster attended last month and where he gave a lecture of honour. "I had a remarkable time," he said. "I am the first British recipient....and it was rather awe-inspiring to have been selected when I looked at the previous Honma prize winners." These include Professor Joseph Takahashi (USA) and Professor Jay Dunlap (USA). "The whole experience was phenomenal," he continued. "I had the opportunity to outline many of the activities in my research group and the presentation went very well. I was also pleased to have an opportunity to visit many of my colleagues in other parts of Japan."

Dr Foster's work in the field of biological rhythms, which began in the early 1990s, was the first to demonstrate that the mammalian eye carries out two quite separate functions. It gathers light to construct an image of the world but the eye also uses light to set the internal biological, or circadian, clock. This clock, located in an area of the brain called the suprachiasmatic nuclei and which regulates all aspects of our physiology and behaviour, is not exactly 24 hours and needs to be re-set on a daily basis by light.

"Our breakthrough was to study mice with hereditary retinal disorders. These mice show no visual responses to light but can regulate their clocks by light normally. This was quite unexpected, but the big problem was how to isolate the components of the eye that regulate the clock from those that regulate vision. More recently we have studied the blind mole rat, an animal with tiny eyes (less than a millimetre in diameter) that are buried beneath its fur. This animal also lacks any brain structures that would enable it to make a visual image. However these animals can regulate their circadian clock by light."

"We know that the eyes mediate these responses because if you cover the eyes, all responses to light cease. We believe that over the past 30 million years evolutionary processes have effectively disentangled the visual photoreceptor system from the circadian photoreceptors in this animal. The blind mole rat thus provides us with a wonderful model to study how the clock is regulated by light," Dr Foster explained.

Dr Foster's team are now trying to discover, using molecular techniques, which opsins in the eye (the protein component of animal photopigments) enable mammals to use light to regulate their body clocks. "We think there is a novel photoreceptor in the eye of mammals and other vertebrates that regulates the clock," Dr Foster speculates. Indeed, very recent PhD work by Bobby Soni in Dr Foster's lab has discovered the first non-rod, non-cone vertebrate photopigment, in the eye of a fish.

"We don't know if this opsin gene, name VA (officially for Vertebrate Ancient but unofficially for Victoria and Albert!), will help with our mammals but at least the idea of novel photoreceptors is made less absurd by the discovery of one in other vertebrates."

He points out that their findings could impact on humans, medically and socially. "If we can establish how to adjust the clock by light, then we can use this information to design approaches to tackle problems like shift-work and jet-lag, and to adjust the clock so that anti-cancer drugs can be given when they are most effective and cause the minimum side-effects."

Dr Foster described another possible benefit. "There has been a tendency to remove the eyes of people who are visually blind as they can be a source of infection. But work by colleagues at the University of Surrey has shown that like our mice and mole rats, humans with no conscious light perception can regulate their clocks by light. This suggests that circadian checks should always be done before eye removal in the visually bind."