How does the eye's retina control circadian rhythms?

Joseph Besharse

"The Circadian Clock in the Eye" is the topic for the Department of Ophthalmology's annual Sidney Futterman Memorial Lecture next week.

Dr. Joseph Besharse, professor and chair of the Department of Cell Biology, Neurobiology and Anatomy at the Medical College of Wisconsin in Milwaukee, will give the lecture at noon, Thursday, April 23, in room T-739 of the Health Sciences Center.

Besharse has been studying how the circadian clock, a built-in mechanism of the photoreceptor cells in the eye's retina, works to control features of photoreceptor metabolism even in the absence of a night-and-day cycle of light. Other structures in the body, including the brain's suprachiasmatic nucleus and pineal gland, also have a role in circadian rhythms.

Although most people are familiar with the concept of circadian rhythms, and the ill effects of their manifestation as jet lag are well known, scientists have not understood precisely how these internal clocks control other functions.

Besharse's research in frog retinas has focused on processes controlled by circadian rhythm, such as photoreceptor disc shedding, melatonin synthesis and synthesis of components needed for phototransduction.

Recently, Besharse's laboratory has identified a rhythmically expressed gene in photoreceptors that produces a novel protein he has named "nocturnin," for night factor. He is now exploring the question of whether nocturnin is the first identified component of a vertebrate clock mechanism, or something "downstream" controlled by other factors.

Besharse received his graduate training in zoology and physiology at Southern Illinois University in Carbondale, where he began studies of the visual system. After postdoctoral research at Columbia, he joined the faculty at Emory University School of Medicine in Atlanta. He was chair of the Department of Anatomy and Cell Biology at the University of Kansas School of Medicine for several years before accepting his current position at the Medical College of Wisconsin in 1997.

He is an editorial board member for several journals and has received several awards for his work, including the Alcon Research Award for Outstanding Research in Vision Science.

The lectureship honors Dr. Sidney Futterman, a member of the School of Medicine's Department of Ophthalmology faculty from 1966 until his death at age 49 in 1979. His research on the metabolism of vitamin A in the retina was widely recognized and he received the Friedenwald Medal, the most prestigious honor of the Association for Research in Vision and Ophthalmology, the year before his death. ¶

Claire Dietz