INFRADIAN CONTROL OF DAPHNIA MAGNA MOLT CYCLE AND ITS DISRUPTION BY NITRIC OXIDE
Biological rhythms are used to control various processes and environmental cues are often used to regulate these molecular clocks. Environmental chemicals may disrupt internal molecular clocks, resulting in adverse consequences. We hypothesized that the timing of the crustacean molt cycle is managed by the sequential expression of several nuclear receptors and cytochrome p450 (CYP) enzymes. We propose that pulsatile nitric oxide controls the availability of one of these receptors and thus acts as a fine-tuner for timing the molt cycle and that exposure to exogenous sources of nitric oxide, e.g. nitrogen fertilizers, can disrupt this timing. Molt-synchronized adult Daphnia magna were exposed to a nitric oxide donor for 8-hours. This resulted in an elongation of the intermolt duration and a significant delay in timing of peak mRNA expression of some of the receptors and CYPs involved in ecdysis. We conclude that exposure to exogenous nitric oxide resulted in delayed peak expression of genes involved in the timing of the intermolt duration with potential adverse consequence on growth and reproductive rates of crustaceans.
Stephanie McKnight (Primary Presenter/Author), North Carolina State University, email@example.com;