GlcAT-P is necessary for both circadian and photoperiodic regulation in Drosophila melanogaster
Creators: name: Patro, Somya
Publisher: name: No Publisher Supplied
Year: 2023

description: Most organisms experience inevitable changes caused by the Earth’s rotation and revolution processes. These changes result in a circadian and circannual rhythm, respectively. In order to develop and survive, organisms must accommodate and adapt to changes in their environment such as changing light-dark cycles and temperatures. Circadian rhythms refer to observable and self-sustaining biological rhythms with an approximately 24-hour period in constant conditions, and control important daily processes such as sleep-wake cycles and hormone secretion. Circannual rhythms arise as a result of different seasons, causing photoperiodic responses which are the responses of an organism to seasonal variations in day-length. Preliminary work conducted in our lab found four candidate genes in Drosophila melanogaster to have a strong association with photoperiodism. Among them, GlcAT-P had the highest association with photoperiodic responses and therefore, this study aimed to understand the influence of GlcAT-P on circadian clock regulation and photoperiodic regulation in Drosophila melanogaster. We tested our hypothesis that GlcAT-P is necessary for circadian clock regulation using locomotor activity as an overt observable rhythm. We aimed to generate knockout mutants of GlcAT-P using CRISPR/Cas9 technology to see the resulting effect of reduced GlcAT-P expression. We found a significant difference in rhythmic nature between the control and resulting GlcAT-P heterozygote mutant flies, allowing us to conclude that GlcAT-P is involved in circadian clock regulation. Additionally, using locomotor activity data of the flies in equinox conditions, we gathered data regarding the phase of entrainment of the flies. We saw the control flies retain their ability anticipate the incoming dusk before it actually happens, which is a circadian-clock controlled trait. Contrastingly, the heterozygote mutant flies of GlcAT-P displayed a lack of anticipation of dusk and instead simply reacted to the conditions of the photoperiod they were placed in. We also tested our hypothesis that GlcAT-P is necessary for photoperiodic regulation by evaluating the day-length dependent ovarian development. The control flies were able to measure the day-length, having undeveloped eggs in their ovaries in short day conditions but developed eggs in their ovaries in long day conditions, owing to the photoperiod being longer than the critical day-length. The heterozygote mutant flies had undeveloped ovaries in both short day and long day conditions at the low temperature, indicating the reduced GlcAT-P expression suppressing egg maturation despite the photoperiod being longer than the critical day-length. These results corroborated the loss of circadian regulation in the heterozygote mutant flies. Collectively, our results showed that GlcAT-P is necessary for both circadian clock regulation and photoperiodic regulation since the heterozygote mutant flies of GlcAT-P lost the circadian-clock controlled locomotor activities and also the day-length dependent egg maturation phenotype.