Influences of Drosophila circadian clock on sugar-mediated physiological changes

Author

Erica E Hassoun, University of LouisvilleFollow

Date on Senior Honors Thesis

5-2022

Document Type

Senior Honors Thesis

Degree Name

B.S.

Department

Biology

Degree Program

College of Arts and Sciences

Author's Keywords

sleep; feeding; Drosophila melanogaster; sugar; physiology; circadian rhythm

Abstract

It is widely known that high sugar consumption and poor sleep are detrimental to human health. Both are risk factors for obesity, which can lead to conditions such as heart disease. Despite this connection between sugar and sleep, little is known about how circadian clock dysfunction affects the physiological changes caused by increased sugar consumption. In this thesis, a mutant line of the model organism Drosophila melanogaster (Clk^Jrk, which contains a nonfunctional circadian rhythm gene known as Clk) that leads to circadian dysfunction, was exposed to a high sugar diet to observe how Clk affects sugar-related changes to food consumption, sleep, triglyceride levels, and starvation resistance. Despite previous research suggesting that the circadian rhythm affects feeding, Clk^Jrk flies did not substantially differ from wild-type flies in terms of food consumption. In addition, both Clk^Jrk and wild-type flies slept less on low-sugar food. However, unlike wild-type flies, Clk^Jrk flies did not experience increased starvation resistance on a high sugar diet, suggesting that a functioning Clk gene is essential for flies fed a high sugar diet to survive when starved. Lowered triglyceride levels in Clk^Jrk flies may explain the reduced starvation resistance of Clk^Jrk flies fed high sugar diets. The findings from this research provide a greater understanding of how sleep and sugar intertwine to affect health and disease. Future studies should explore the endocrine components of this relationship in Drosophila, particularly the Drosophila Insulin-Like Peptides (DILPs), which regulate nutrient storage and release.

Recommended Citation

Hassoun, Erica E, "Influences of Drosophila circadian clock on sugar-mediated physiological changes" (2022). College of Arts & Sciences Senior Honors Theses. Paper 271.
Retrieved from https://ir.library.louisville.edu/honors/271

Lay Summary

High sugar diets and poor sleep are unhealthy for humans. Both are risk factors for obesity, which can lead to conditions such as heart disease. Despite this connection, little is known about how dysfunction of the circadian clock (an internal process that controls the timing of sleep) affects changes to the body caused by increased sugar consumption.

To explore this, the fruit fly was used as a model organism. A fruit-fly mutant with a dysfunctional circadian clock was exposed to a high sugar diet to observe the circadian clock affects sugar-related changes to food consumption, sleep, and energy storage. Despite previous research suggesting that the circadian clock affects feeding, mutant flies did not differ from non-mutants in the amount of food they consumed. In addition, both mutants and non-mutants slept less on low-sugar food. However, when food was withheld from flies in order to observe how they used stored energy, there was evidence that mutant flies used and stored their energy differently than non-mutants. These interesting findings show how sleep and diet work together to affect health.