ABSTRACT
Phototransduction, the mechanism underlying the electrical response to light in photoreceptor cells, has been thoroughly investigated in Drosophila melanogaster, an essential model in signal transduction research. These cells present a highly specialized photosensitive membrane consisting of thousands of microvilli forming a prominent structure termed a rhabdomere. These microvilli encompass the phototransduction proteins, most of which are transmembrane and exclusively rhabdomeric. Rhabdomere membrane lipids play a crucial role in the activation of the transient receptor potential ionic channels (TRP and TRPL) responsible for initiating the photoresponse. Despite its importance, rhabdomere lipid composition has not been established. We developed a novel preparation enriched in rhabdomere membranes to perform a thorough characterization of the lipidomics of Drosophila rhabdomeres. Isolated eyes (500) were homogenized and subjected to a differential centrifugation protocol that generates a fraction enriched in rhabdomere membrane. Lipids extracted from this preparation were identified and quantified by gas chromatography coupled to mass spectrometry. We found an abundance of low sterol esters (C16:0, C18:0), highly abundant and diverse triglycerides, free fatty acids, a moderate variety of mono and diacyglycerols (C:16:0, 18:0, C18:1) and abundant phospholipids (principally C18:2). This preparation opens a new avenue for investigating essential aspects of phototransduction.
Subject(s)
Animals , Drosophila Proteins/chemistry , Drosophila melanogaster/chemistry , Fatty Acids/analysis , Microvilli/chemistry , Photoreceptor Cells, Invertebrate/chemistry , Transient Receptor Potential Channels/chemistry , Drosophila Proteins/analysis , Light Signal Transduction/physiology , Protein Transport/physiology , Transient Receptor Potential Channels/analysisABSTRACT
In mammals, neurogenesis continues during adulthood in restricted places of the nervous system, namely the subventricular zone, the dentate gyms and the olfactory epithelium. A dual role of the second messenger nitric oxide has been reported in such places, either promoting or inhibiting proliferation of neuronal precursors depending on the cellular signal implicated. In this review the regulation of adult olfactory epithelium neurogenesis by nitric oxide is discussed.