Cyclical expression of the sodium pump alpha-subunit gene and protein in the visual system of Drosophila melanogaster
In the lamina L1 and L2 monopolar cells show circadian rhythms in shape and size changes, however, mechanisms of these rhythms have not been recognized yet. It has been proposed that swelling and shrinking of L1 and L2 interneurons might be due to ionic fl uxes, changes in cytoskeleton organization and in protein synthesis. This process also depends on glial cell activity. Since ion channels seem to be involved in morphological plasticity of neurons and glial cells we examined expression of the sodium pump, Na+ ,K+ -ATPase, during the day and night. The sodium pump consists of two polypeptide chains: α- and β-subunits encoded by the Atpα and Nrv2 genes, respectively. Using the real-time PCR and immunohistochemistry methods we found the α-subunit shows daily changes in mRNA and protein concentrations while in case the β-subunit such changes were not observed. Since the rhythm in the α-subunit abundance was not observed in the per0 arrhythmic mutant, this rhythm is controlled by clock genes. It seems to refl ect changes in the visual system activity.