A screening of genes related to circadian rhythm in the 3rd chromosome of drosophila melanogaster

Abstract

The Earth’s rotation causes the periodic changes of light and temperature. These environmental changes affect the behavioral or biochemical activities of the living organisms. The organisms from prokaryotic organisms to animal have daily rhythms in physiology, metabolic activity and behaviors and this rhythms depend on the cyclic changes of light and temperature. Circadian rhythm is 24 h cycle in living entities. It is controlled by endogenous circadian clock of organisms. Circadian system of drosophila melanogaster has interlocked transcriptional feedback loops involving several transcriptional factors and their interactions. Several circadian core clocks like per, timless (tim), Clock (Clk), cycle (cyc) and doubletime (dbt) were characterized. The expression levels of circadian transcriptional factor oscillate in daily patterns. In one loop, dCLK/CYC activates per and tim gene expression, and PER/TIM then inhibits dCLK/CYC activity. In the other loop, dCLK/CYC also activates vri and Pdp1ε gene expression, and VRI and PDP1ε then repress or activate dClk transcription. In adult fly brain, there are six goups of clock pacemaker cells. They are small and large lateral ventral neurons, lateral dorsal neurons, and three groups of dorsal neurons and small and large ventral neurons express PDF. PDF is the best characterized molecule of the circadian output pathways and thought to be an output neurotransmitter of the circadian clock. In this study, we focused to search the novel circadian gene in drosophila’s 3rd chromosome. We performed the screening over 3rd chromosome genes by using EP lines in which p element was inserted. Then, we found out two candidates, sra and CG1233, involved in circadian rhythm. The behaviors of their mutant were measured and their effects on core clock molecules and PDF expression were identified. In this context, we investigated the role of sra and CG1233 genes in the regulation of circadian rhythm, and demonstrate that two genes are re...