Influence of High Fat Diet, Bacterial Infection and Clock Mutation on Circadian Rhythm and Sensory Modalities of Drosophila Melanogaster

Abstract

Circadian clock is an endogenous time keeping system which is conserved from bacteria to human beings. Years of research in vertebrates, suggest close association of circadian clock with parameters like metabolism, physiology, aging, sleep, behavior, neurodegeneration and other metabolic disorder. Several model organisms including Drosophila melanogaster are used to establish the role of circadian rhythm in day to day activity. The current study aims to investigate the role of three key parameters on circadian rhythm. The first parameter is high-fat diet mediated diabesity and its effect on circadian rhythm. For this experiment the larva and adults of D.melanogaster were exposed to high-fat diet (HFD) through oral route. After feeding the larva and adults have excess fat and micronuclei within the gut, fat body, and crop. Larva and adults of HFD showed behavioral defects, impaired metabolite profile, and overexpression of insulin gene (Dilp2) and tribble (trbl) gene confirmed insulin resistance. Elevated ROS level, developmental delay, altered metal level, growth defects, locomotory rhythms, sleep fragmentation, and expression of circadian genes (per, tim, and clock) in HFD larva and adults. In the second objective the effect of host pathogen interaction and its co-relation between circadian rhythm was established. For this study both gram-negative bacteria, Pseudomonas aeruginosa and gram-positive bacteria Staphylococcus aureus was examined on D. melanogaster physiology, behavior and circadian clock. Infections lead to phenotype and behavioral defects, developmental delay, oxidative stress and nuclear damages in larvae as well as adults. Increased level of expression of immune genes and disrupted circadian clock related co-mordities in Drosophila melanogaster were detected. The third objective checked Drosophila clock (ClkJrkst) mutation on behavioral and molecular changes in their eye and hearing organ, defective oxidative state, and status of TRP channel genes, physiology, metabolism, and behavior in Drosophila. The current study suggests the chronobiological consideration towards treatment for type-II diabetes, infectious disease and circadian anomalies.