Date of Graduation

5-2026

Document Type

Thesis

Degree Name

Bachelor of Science in Biology

Degree Level

Undergraduate

Department

Biological Sciences

Advisor/Mentor

Amy Poe

Abstract

Circadian clocks regulate daily physiological and metabolic rhythms across many organisms. In Drosophila melanogaster, the molecular clock involving period (per) and timeless regulates gene expression across 24-hour cycles. Circadian rhythms are well characterized in adult, mature organisms, but their emergence during early developmental stages remain poorly understood. In D. melanogaster, the circadian regulation of sleep and feeding rhythms emerges during the 3rd instar larval stage. This suggests that the circadian regulation of metabolism may also arise during this stage. Further, the metabolic consequences of circadian clock disruptions during this developmentally rich period remain unclear. This research aimed to determine if metabolic rhythms differ between second- and third-instar larvae and whether a disruption of the molecular circadian clock affects these rhythms. This research additionally developed a method for examining lipid metabolites in D. melanogaster larvae using mass spectrometry. Whole-body levels of glucose, glycogen, cholesterol, and trehalose did not exhibit significant daily rhythmicity in third-instar larvae. However, triglyceride levels were clearly rhythmic across the day in isogenic third-instar larvae and lost this rhythm in both per mutant (per01) and second-instar larvae. The results of this research suggest that some metabolic rhythms emerge during the transition from the second- to third-instar stage and may partly depend on molecular circadian clock machinery. These findings highlight that triglyceride metabolism may come under circadian control earlier than the metabolism of other metabolites. Understanding how circadian metabolism develops may provide insights into how disruptions in biological clocks influence metabolic regulation during early life stages.

Keywords

fruit fly; metabolism; mass spectrometry; sterols; larvae

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