Circadian rhythms are a universal feature of eucaryotic systems. They are typified by a daily oscillation in some physiologic response, usually to a light/dark cycle, that persists even in the absence of such an external cue. Such rhythms include thermoregulation, cell division, cellular response to applied drugs, and the levels of several mRNA species, such as opsin and vasopressin. While many such cyclic phenomena have been detected, the underlying mechanism responsible for the "clock" has remained elusive. This fellwoship research will deal with the mechanisms of translational control of circadian bioluminescence in the marine dinoflagellate Gonyaulax polyedra. A luciferin/luciferase system is responsible for the generation of time-dependent expression of bioluminescence. A luciferin-binding protein (LBP) is required to stabilize the high energy substrate prior to photon release. This protein is expressed only during a brief period at the onset of night phase, as a result of rapid synthesis, and is selectively degraded several hours later. Northern blot analysis of LBP mRNA levels indicate that the transcript for the LBP is constitutively expressed, indicating the increased expression of the LBP is a result of activation of latent mRNA (translational control), rather than increased gene activity (transitional control). This project will serve the dual purpose of broadening knowledge of dinoflagellate gene expression and elucidating the mechanism of circadian regulation of specific proteins.
