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----------------------------------------------------------------------- Men, you have a biological clock too ----------------------------------------------------------------------- WASHINGTON (November 28, 1997 4:53 p.m. EST http://www.nando.net) - Your biological clock -- the internal mechanism that helps you sleep at night and wake in the morning -- might not be just in your head, scientists have found. If you're a male, it's probably also in your testicles. "It does give a whole new meaning to the rhythm method," said Steve Kay, a cell biologist at the Scripps Research Institute in San Diego. Scientists used to believe that the human body's clock was all inside the brain, in a place called the superchiasmatic nucleus, but a new study in Thursday's edition of the journal Science found that clocks may be ticking all over the body. These clocks, determined in different animals by different genes, respond to daily changes in light over the course of a day and to the more gradual changes in light over the course of a year. In flies, mice and men, the gene is called the period gene. "Recently the period gene has been found to be in humans," Kay said in a telephone interview. "The place where the period gene is most highly expressed in mouse and I think in humans is the testes." Kay and other researchers at Brandeis University in Boston and at the National Science Foundation's Center for Biological Timing studied fruit flies to determine where the period gene was working to set the body's circadian rhythms. The scientists identified this so-called period gene, spliced it with a jellyfish gene that stained the period gene fluorescent green, and looked at the flies under microscopes. The period gene was all over the insects: in the digestive tract, in the mouth, on the feet and legs and at the base of tiny hairs, according to Steve Kay of the Scripps Research Institute in La Jolla, California. With a bit more genetic splicing, using firefly genes this time, the scientists managed to find which of these biological clocks were actually ticking in the fruit flies, Kay said in a telephone interview. Many of them were ticking with 24-hour regularity, and this was visible because parts of the fruit flies glowed dull yellow and dimmed over a one-day cycle, independently of the flies' brains. The study of these individual genes may shed light on such larger biological clock-related ailments as seasonal-affective disorders, which are characterized by depression in some people during the darker, winter months. It could also lead to new strategies for the treatment of jet lag and shift work, the scientists said. By DEBORAH ZABARENKO, Reuters Copyright 1997 Nando.net Copyright 1997 Reuters http://www.nando.net/newsroom/ntn/health/112897/health9_3352_noframes.html -----------------------------------------------------------------------