The major goal of this project is to isolate a piece of genetic material (complementary DNA) for the retinal/pineal gene coding for N-acetyltransferase (NAT). After verifying the structure of this enzyme, NAT gene expression will be examined during neurochemical transduction in the light:dark cycle. Neurochemical transduction in the pineal involves the conversion of one signal, the release of norepinephrine at the surface of the pinealocyte, into a second signal, the release of melatonin from within the pinealocyte. The cyclic rhythm of retinal and pineal melatonin is dependent on the enzyme, NAT. NAT is synchronized by the light:dark cycle of the environment. The pineal melatonin functions as a synchronizer that entrains physiology to the appropriate season of the year. The retinal melatonin, which has similar controlling elements and light:dark responses as the pineal, may also be responsible for this environmental synchronization. In addition, retinal melatonin affects various retinal functions: photoreceptor outer-disc shedding, pigment granule aggregation, cellular levels of second messengers, and release of transmitters. Alteration of melatonin synthesis may alter the ability of the eye to perceive light as a cue for rhythm synchronization. Even though the physiological significance of melatonin is still not known, this project will clearly extend basic knowledge of this indoleamine in the visual and signal transduction process. Practical applications of the research would include using the probe in mapping the human genome and as a genetic marker. The experiments described will employ recombinant DNA tools to begin examining the influence of environmental cues on the genes expressed in the pineal and retina. The pineal has been studied extensively by physiological, pharmacological and biochemical approaches. These studies will extend the knowledge of the normal structure of genes expressed in the individual and may lead to understanding the involvement of other synthesizing enzymes in regulating normal physiological functions.
