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
Mutations in the Fused in sarcoma/Translated in liposarcoma gene (FUS/TLS, FUS) have been identified among patients with amyotrophic lateral sclerosis (ALS). FUS protein aggregation is a major pathological hallmark of FUS proteinopathy, a group of neurodegenerative diseases characterized by FUS-immunoreactive inclusion bodies. We prepared transgenic Drosophila expressing either the wild type (Wt) or ALS-mutant human FUS protein (hFUS) using the UAS-Gal4 system. When expressing Wt, R524S or P525L mutant FUS in photoreceptors, mushroom bodies (MBs) or motor neurons (MNs), transgenic flies show age-dependent progressive neural damages, including axonal loss in MB neurons, morphological changes and functional impairment in MNs. The transgenic flies expressing the hFUS gene recapitulate key features of FUS proteinopathy, representing the first stable animal model for this group of devastating diseases.
Subject(s)
Aged , Animals , Humans , Aging , Genetics , Metabolism , Pathology , Amyotrophic Lateral Sclerosis , Genetics , Metabolism , Pathology , Animals, Genetically Modified , Disease Models, Animal , Drosophila melanogaster , Genetics , Metabolism , Gene Expression , Microscopy, Electron, Scanning , Motor Neurons , Metabolism , Pathology , Mushroom Bodies , Metabolism , Pathology , Mutant Proteins , Genetics , Metabolism , Mutation , Photoreceptor Cells, Invertebrate , Metabolism , Pathology , Plasmids , RNA-Binding Protein FUS , Genetics , Metabolism , Recombinant Fusion Proteins , Genetics , Metabolism , Retinal Degeneration , Pathology , TransfectionABSTRACT
Retinitis pigmentosa is a leading cause of blindness and a progressive retinal disorder, affecting millions of people worldwide. This disease is characterized by photoreceptor degeneration, eventually leading to complete blindness. Autosomal dominant (adRP) has been associated with mutations in at least four ubiquitously expressed genes encoding pre-mRNA splicing factors-Prp3, Prp8, Prp31 and PAP1. Biological function of adRP-associated splicing factor genes and molecular mechanisms by which mutations in these genes cause cell-type specific photoreceptor degeneration in humans remain to be elucidated. To investigate the in vivo function of these adRP-associated splicing factor genes, we examined Drosophila in which expression of fly Prp31 homolog was down-regulated. Sequence analyses show that CG6876 is the likely candidate of Drosophila melanogaster Prp31 homolog (DmPrp31). Predicted peptide sequence for CG6876 shows 57% similarity to the Homo sapiens Prp31 protein (HsPrp31). Reduction of the endogenous Prp31 by RNAi-mediated knockdown specifically in the eye leads to reduction of eye size or complete absence of eyes with remarkable features of photoreceptor degeneration and recapitulates the bimodal expressivity of human Prp31 mutations in adRP patients. Such transgenic DmPrp31RNAi flies provide a useful tool for identifying genetic modifiers or interacting genes for Prp31. Expression of the human Prp31 in these animals leads to a partial rescue of the eye phenotype. Our results indicate that the Drosophila CG6876 is the fly ortholog of mammalian Prp31 gene.
Subject(s)
Animals , Humans , Amino Acid Sequence , Animals, Genetically Modified , Base Sequence , DNA Primers , Genetics , Drosophila Proteins , Genetics , Physiology , Drosophila melanogaster , Genetics , Physiology , Eye Abnormalities , Genetics , Eye Proteins , Genetics , Physiology , Gene Knockdown Techniques , Genes, Insect , Molecular Sequence Data , Pancreatitis-Associated Proteins , Photoreceptor Cells, Invertebrate , Physiology , RNA Interference , RNA Splicing , Sequence Homology, Amino AcidABSTRACT
La evolución de los ojos comenzó cuando comenzó la vida misma. Incluso las formas de vida más simples, las bacterias, tienen las primeras proteínas fotosensibles. Desde las bacterias la vida y la visión evolucionaron hacia una asombrosa variedad y complejidad: ojos telescópicos, ojos especulares, ojos tipo cámara, todos ellos con un solo origen.
The evolution ofthe eyes began when the life itself began. Even the simplest life forms, the bacteria, have the first photosensitive proteins. From the bacteria, the life and the vision evolved towards an astonishing variety and complexity: telescope eyes, mirror eyes, camera eyes, between many others, all ofthem with a single source.
Subject(s)
Humans , Animals , Biological Evolution , Eye/anatomy & histology , Eye/growth & development , Photoreceptor Cells, Invertebrate , Photoreceptor Cells, VertebrateABSTRACT
BACKGROUND & OBJECTIVES: Anopheles stephensi, an important vector of malaria continues to be distributed widely in the Indian subcontinent. This vector species has developed resistance for various insecticides. Therefore, it is desirable to develop alternate strategy, which does not involve resistance. In order to develop such strategy, it is mandatory that genetic studies of concerned vector species should be established. This paper describes the isolation and genetic studies of an eye colour mutant, ruby-eye (ru), and linkage studies involving another autosomal recessive mutant greyish brown larva (grb ru) in A. stephensi. METHODS: The stocks of mutants ruby-eye (ru), greyish brown (grb ru) and wild type mosquitoes were maintained in the laboratory. Crosses were made between the wild type and mutant to determine the mode of inheritance of ruby-eye. For linkage studies crosses were made between the mutant ruby-eye and another autosomal recessive mutant greyish brown larva. The percentage cross over was calculated for the genes linkage relationship for ru and grb ru. RESULTS: Results of crosses between mutant and wild type show that the inheritance of ruby-eye in A. stephensi is monofactorial in nature. The ru allele is recessive to wild type and is autosomal. The linkage studies showed no linkage between grb and ru. INTERPRETATION & CONCLUSION: The mutant ru represents an excellent marker for A. stephensi as it expresses in all the life stages with complete penetrance and high viability. This mutant can be used extensively to conduct basic and applied research.
Subject(s)
Animals , Anopheles/genetics , Genes, Insect , Insect Vectors/genetics , Larva/anatomy & histology , Genetic Linkage , Malaria , Mutation , Photoreceptor Cells, Invertebrate/metabolism , Pigmentation/geneticsABSTRACT
Invertebrate visual transduction involves a second messenger cascade process that leads to an increase in membrane conductance. The identity of the second messenger that gates the light-dependent channels is presently a major focus of attention. Cyclic GMP, inositol trisphosphate and Ca2+ are the most likely candidates for being such a messenger in the species studied so far. Here we review the available evidence for each of these molecules