Cyclical expression of Na +/K +-ATPase in the visual system of Drosophila melanogaster

• Published in: Journal of insect physiology 2009-05, Vol.55 (5), p.459-468
• Main Authors: Górska-Andrzejak, Jolanta, Salvaterra, Paul M., Meinertzhagen, Ian A., Krzeptowski, Wojciech, Görlich, Alicja, Pyza, Elżbieta
• Format: Article
• Language: English
• Subjects: Animals; circadian clock; Circadian Rhythm; Circadian rhythms; Drosophila melanogaster; Drosophila melanogaster - enzymology; Drosophila melanogaster - genetics; Drosophila melanogaster - physiology; Drosophila Proteins - genetics; Drosophila Proteins - metabolism; Female; gene expression; Gene Expression Regulation, Enzymologic; Glial cells; green fluorescent protein; Green fluorescent protein (GFP); immunohistochemistry; Male; messenger RNA; Nervana; neuroglia; neurons; Neuropil - enzymology; Neuropil - physiology; Optic lobe; Pigment dispersing factor (PDF); protein subunits; Protein Subunits - genetics; Protein Subunits - metabolism; protein synthesis; reporter genes; Sodium pump; Sodium-Potassium-Exchanging ATPase - genetics; Sodium-Potassium-Exchanging ATPase - metabolism; transgenic insects; vision; Visual Pathways - enzymology; Visual Pathways - physiology
• ISSN: 0022-1910; 1879-1611
• DOI: 10.1016/j.jinsphys.2009.02.003

In the first (lamina) and second (medulla) optic neuropils of Drosophila melanogaster, sodium pump subunit expression changes during the day and night, controlled by a circadian clock. We examined α-subunit expression from the intensity of immunolabeling. For the β-subunit, encoded by Nervana 2 ( Nrv2), we used Nrv2-GAL4 to drive expression of GFP, and measured the resultant fluorescence in whole heads and specific optic lobe cells. All optic neuropils express the α-subunit, highest at the beginning of night in both lamina and medulla in day/night condition and the oscillation was maintained in constant darkness. This rhythm was lacking in the clock arrhythmic per 0 mutant. GFP driven by Nrv2 was mostly detected in glial cells, mainly in the medulla. There, GFP expression occurs in medulla neuropil glia (MNGl), which express the clock gene per, and which closely contact the terminals of clock neurons immunoreactive to pigment dispersing factor. GFP fluorescence exhibited circadian oscillation in whole heads from Nrv2-GAL4 + UAS-S65T-GFP flies, although significant GFP oscillations were lacking in MNGl, as they were for both subunit mRNAs in whole-head homogenates. In the dissected brain tissues, however, the mRNA of the α-subunit showed a robust daily rhythm in concentration changes while changes in the β-subunit mRNA were weaker and not statistically significant. Thus in the brain, the genes for the sodium pump subunits, at least the one encoding the α-subunit, seem to be clock-controlled and the abundance of their corresponding proteins mirrors daily changes in mRNA, showing cyclical accumulation in cells.