Krznarich, Jennifer2017-11-272017-11-272017-08https://hdl.handle.net/11299/191262University of Minnesota M.S. thesis. August 2017. Major: Biological Science. Advisor: Jennifer Liang. 1 computer file (PDF); vi, 83 pages.The circadian clock is an intracellular transcriptional-translational feedback loop that drives circadian rhythms. In zebrafish, these circadian clocks are found throughout the body and can be directly entrained by light. Melatonin synthesis begins early in zebrafish development (~22 hours post fertilization) and nocturnal melatonin biosynthesis is one of the first signs of the circadian system. Our data suggest that melatonin does not play a role in establishment of daily gene expression rhythms in developing zebrafish. We found that melatonin or a melatonin receptor antagonist did not impact expression of circadian clock-controlled genes (irbp and aanat2) or genes encoding components of the circadian clock (period3 and clock1). However, consistent with research by others suggesting that melatonin accelerates development, our preliminary work suggests that melatonin may advance gene expression onset of dbx2 and irbp in the first 24 hours of development.enThesis or Dissertation