9601382 Roberts One of the most interesting features of the nervous system is the fact that it is able to undergo functional changes. These changes may occur due to experience - learning - or may be based upon internally generated changes in nerve cell physiology and biochemistry. One common change in nerve cell function, that has been observed in virtually all organisms including humans, are the changes that follow the daily environmental cycle of light and darkness. Interestingly, these daily changes in nerve cell function are not reflexive responses to the environment, but instead are regulated by an internal timing system. The internal timing system is controlled by circadian pacemakers (circa - about dies - a day) or "biological clocks" located in the brain or other neural structures. Investigation of circadian pacemakers over the past several years has indicated that disruption in the function of the circadian clock, and the circadian timing system, leads to multiple problems in human physiology. Furthermore, the interaction between the circadian timing system (internal rhythmicity) is of critical importance in gaining a full understanding of an organism's relationship with its environment. Finally, it has been shown that biological clocks function through the interaction of many intracellular biochemical processes such as gene transcription, translation, and protein modification. The purpose of our work is to investigate the biochemistry of circadian clock function in a model neural system. In these studies we will analyze the role played by two specific classes of protein (cyclin-dependent kinases, and mitogen activated protein kinases) that we propose are important in the generation and regulation of the circadian rhythm produced in the eye of the marine snail, Bulla gouldiana. Investigation of several different circadian pacemakers has shown that clock function has been conserved in a diverse group of organisms. Thus, our studies should pr ovide general insights concerning the biochemistry of circadian rhythm generation.
