Preliminary Study On The Effect Of Starvation On The Expression Of The Olfactory Receptor Gene Orco In Drosophila Melanogaster

The life of insects is mainly for “eating” and “breed”.Only by obtaining adequate nutrition can it reproduce offspring.The first step in getting adequate nutrition is to find food.The olfactory system plays an important role in many physiological behaviors of insects.As the most widely expressed olfactory receptor in the olfactory system,Orco plays a key role in the process of odor recognition in food search.Starvation can affect the level of insulin in the organism,and the insulin signaling pathway can participate in the regulation of body metabolism.In recent years,studies have also confirmed that this pathway also has an important function in the feeding process of insects,but the relationship between the insulin signaling pathway and the olfactory receptor gene orco has not been clearly reported.As one of the classic model organisms,Drosophila melanogaster has the characteristics of short life cycle,easy breeding,few chromosomes,and small individuals.At the same time,Drosophila melanogaster has a clear genetic background and convenient genetic operations,so it is widely used as a research object in genetic,behavioral and physiology experiments.In this study,the structure and evolution of Orco protein in Drosophila melanogaster were analyzed.The effects of starvation on the expression of orco gene in Drosophila melanogaster were studied by behavioral experiments,Western blot,qPCR,immunofluorescence staining,Dual luciferase reporter assay and ChIP-PCR.The main results are as follows:(1)Orco protein structure and evolution analysisThrough bioinformatics analysis,it is found that the molecular weight of the Drosophila olfactory receptor Orco protein is 54.4 kDa,the isoelectric point is 8.72,and the protein is alkaline.Orco is a 7-pass transmembrane protein with no signaling peptide.The secondary structure is mainly alpha helix and random coil;the sequence of Drosophila Orco protein is evolutionarily close to Muscidae and Tephritidae;(2)Starvation enhances orco expression and promotes feeding behavior in DrosophilaConduct behavioral experiments by enhancing or knocking down the expression of orco gene and rescue experiments to prove that the olfactory receptor gene orco plays an important role in the feeding behavior of Drosophila;At the same time,when Drosophila are starved,use qPCR,Western Blot and antibody staining of Drosophila tissues found that the m RNA level and protein level of orco in the body were significantly increased,and starvation promoted the feeding behavior of Drosophila;(3)The insulin signaling pathway transcription factor FoxO directly regulates the expression of orcoIt is found through qPCR that starvation can promote the expression of most genes related to the insulin signaling pathway;behavioral experiments have proved that the transcription factor FoxO in the insulin signaling pathway can affect the feeding behavior of Drosophila;the dual luciferase reporter experiment and ChIP-PCR experiment verified that the transcription factor FoxO directly binds to the intron region of the olfactory receptor gene orco to positively regulate it.