Discordant Responses to MAPK Pathway Stimulation Include Axonal Growths in Adult Photoreceptors.

Wallenda (WND) is the member of a conserved family of dual leucine-zipper kinases (DLK) active in both neuronal regeneration and degeneration. We examined the role of WND over-expression on sensory neuron morphology by driving WND in multiple subtypes of photoreceptors. WND overexpression under control of the pan-retinal GAL4 driver GMR causes multiple photoreceptor defects including cell death, rhabdomere degeneration, and axonal sprouting.

Light-Driven Processes Control Both Rhodopsin Maturation and Recycling in Mosquito Photoreceptors.

Unlabelled: Many invertebrates carry out a daily cycle of shedding and rebuilding of the photoreceptor's photosensitive rhabdomeric membranes. The mosquito Aedes aegypti shows a robust response, losing nearly all Aaop1 rhodopsin from the rhabdomeric membranes during the shedding process at dawn. Here, we made use of Aaop1 antibodies capable of distinguishing newly synthesized, glycosylated rhodopsin from mature nonglycosylated rhodopsin to characterize the fate of Aaop1 during the shedding and rebuilding processes.

Invertebrate and vertebrate class III myosins interact with MORN repeat-containing adaptor proteins.

In Drosophila photoreceptors, the NINAC-encoded myosin III is found in a complex with a small, MORN-repeat containing, protein Retinophilin (RTP). Expression of these two proteins in other cell types showed NINAC myosin III behavior is altered by RTP. NINAC deletion constructs were used to map the RTP binding site within the proximal tail domain of NINAC.

Expression and light-triggered movement of rhodopsins in the larval visual system of mosquitoes.

During the larval stages, the visual system of the mosquito Aedes aegypti contains five stemmata, often referred to as larval ocelli, positioned laterally on each side of the larval head. Here we show that stemmata contain two photoreceptor types, distinguished by the expression of different rhodopsins. The rhodopsin Aaop3 (GPROP3) is expressed in the majority of the larval photoreceptors.

A database of circadian and diel rhythmic gene expression in the yellow fever mosquito Aedes aegypti.

Background: The mosquito species Aedes aegypti is the primary vector of many arboviral diseases, including dengue and yellow fevers, that are responsible for a large worldwide health burden. The biological rhythms of mosquitoes regulate many of the physiological processes and behaviors that influence the transmission of these diseases. For insight into the molecular basis of biological rhythms, diel and circadian gene expression profiling has been carried out for many species.

Rhodopsin management during the light-dark cycle of Anopheles gambiae mosquitoes.

The tropical disease vector mosquito Anopheles gambiae possesses 11 rhodopsin genes. Three of these, GPROP1, GPROP3, and GPROP4, encode rhodopsins with >99% sequence identity. We created antisera against these rhodopsins and used immunohistology to show that one or more of these rhodopsins are expressed in the major R1-6 photoreceptor class of the adult A.

Role of semaphorin-1a in the developing visual system of the disease vector mosquito Aedes aegypti.

Background: Despite the devastating impact of mosquito-borne illnesses on human health, very little is known about mosquito developmental biology, including development of the mosquito visual system. Mosquitoes possess functional adult compound eyes as larvae, a trait that makes them an interesting model in which to study comparative developmental genetics. Here, we functionally characterize visual system development in the dengue and yellow fever vector mosquito Aedes aegypti, in which we use chitosan/siRNA nanoparticles to target the axon guidance gene semaphorin-1a (sema1a).

Rhodopsin coexpression in UV photoreceptors of Aedes aegypti and Anopheles gambiae mosquitoes.

Differential rhodopsin gene expression within specialized R7 photoreceptor cells divides the retinas of Aedes aegypti and Anopheles gambiae mosquitoes into distinct domains. The two species express the rhodopsin orthologs Aaop8 and Agop8, respectively, in a large subset of these R7 photoreceptors that function as ultraviolet receptors. We show here that a divergent subfamily of mosquito rhodopsins, Aaop10 and Agop10, is coexpressed in these R7 photoreceptors.

Light-mediated control of rhodopsin movement in mosquito photoreceptors.

Multiple mechanisms contribute to a photoreceptor's ability to adapt to ambient light conditions. The mosquito Aedes aegypti expresses the long-wavelength rhodopsin Aaop1 in all R1-R6 photoreceptors and most R8 photoreceptors. These photoreceptors alter the cellular location of Aaop1 and reorganize their photosensitive rhabdomeric membranes on a daily basis.

A role for the cytoplasmic DEAD box helicase Dbp21E2 in rhodopsin maturation and photoreceptor viability.

The Dbp21E2 (DEAD box protein 21E2) is a member of a family of DEAD box helicases active in RNA processing and stability. The authors used genetic mosaics to identify mutants in Dbp21E2 that affect rhodopsin biogenesis and the maintenance of photoreceptor structure. Analysis of a green fluorescent protein (GFP)-tagged Rh1 rhodopsin construct placed under control of a heat shock promoter showed that Dbp21E21 fails to efficiently transport Rh1 from the photoreceptor cell body to the rhabdomere.

Coexpression of spectrally distinct rhodopsins in Aedes aegypti R7 photoreceptors.

The retina of the mosquito Aedes aegypti can be divided into four regions based on the non-overlapping expression of a UV sensitive Aaop8 rhodopsin and a long wavelength sensitive Aaop2 type rhodopsin in the R7 photoreceptors. We show here that another rhodopsin, Aaop9, is expressed in all R7 photoreceptors and a subset of R8 photoreceptors. In the dorsal region, Aaop9 is expressed in both the cell body and rhabdomere of R7 and R8 cells.

Retinophilin is a light-regulated phosphoprotein required to suppress photoreceptor dark noise in Drosophila.

Photoreceptor cells achieve high sensitivity, reliably detecting single photons, while limiting the spontaneous activation events responsible for dark noise. We used proteomic, genetic, and electrophysiological approaches to characterize Retinophilin (RTP) (CG10233) in Drosophila photoreceptors and establish its involvement in dark-noise suppression. RTP possesses membrane occupation and recognition nexus (MORN) motifs, a structure shared with mammalian junctophilins and other membrane-associated proteins found within excitable cells.

Expression of two self-enhancing antifreeze proteins from the beetle Dendroides canadensis in Drosophila melanogaster.

Antifreeze proteins (AFPs) lower the freezing point of water without affecting the melting point. This difference between melting point and freezing point has been termed thermal hysteresis. Antifreeze protein genes, dafp-1 and/or dafp-4, from the freeze-avoiding insect, Dendroides canadensis, were transferred to Drosophila melanogaster via P-element-mediated transformation.

Patterned rhodopsin expression in R7 photoreceptors of mosquito retina: Implications for species-specific behavior.

Visual perception of the environment plays an important role in many mosquito behaviors. Characterization of the cellular and molecular components of mosquito vision will provide a basis for understanding these behaviors. A unique feature of the R7 photoreceptors in Aedes aegypti and Anopheles gambiae is the extreme apical projection of their rhabdomeric membrane.

Cellular sites of Drosophila NinaB and NinaD activity in vitamin A metabolism.

The Drosophila genes ninaB and ninaD, encoding a beta-carotene oxygenase and a type B scavenger receptor respectively, are essential for the biosynthesis of the 3-hydroxyretinal chromophore of rhodopsin. We analyzed transgenic reporter strains and performed in situ hybridization to show that both ninaB and ninaD are expressed in the adult brain but not retinal tissues. Developmental RT-PCR and tissue expression studies showed that ninaB is only expressed in the adult brain, while ninaD is expressed in the adult brain, the adult body, and many larval tissues.

The Drosophila rhodopsin cytoplasmic tail domain is required for maintenance of rhabdomere structure.

The ninaE-encoded Rh1 rhodopsin is the major light-sensitive pigment expressed in Drosophila R1-6 photoreceptor cells. Rh1 rhodopsin localizes to and is essential for the development and maintenance of the rhabdomere, the specialized membrane-rich organelle that serves as the site of phototransduction. We showed previously that the vertebrate bovine rhodopsin (Rho) is expressed and properly localized in Drosophila photoreceptor cells.

Probing rhodopsin-transducin interaction using Drosophila Rh1-bovine rhodopsin chimeras.

Invertebrate and vertebrate rhodopsins share a low degree of homology and are coupled to G-proteins from different families. Here we explore the utility of fly-expressed chimeras between Drosophila rhodopsin Rh1 and bovine rhodopsin (Rho) to probe the interactions between the invertebrate and vertebrate visual pigments and their cognate G-proteins. Chimeric Rh1 pigments carrying individual substitutions of the cytoplasmic loops C2 and C3 and the C-terminus with the corresponding regions of Rho retained the ability to stimulate phototranduction in Drosophila, but failed to activate transducin.

Heterologous expression of bovine rhodopsin in Drosophila photoreceptor cells.

Purpose: Vertebrate and invertebrate visual pigments are similar in amino acid sequence, structural organization, spectral properties, and mechanism of action, but possess different chromophores and trigger phototransduction through distinct biochemical pathways. The bovine opsin gene (Rho) was expressed in Drosophila, to examine the properties of a vertebrate opsin within invertebrate photoreceptor cells.

Methods: Transgenic Drosophila expressing the bovine opsin gene (Rho) in photoreceptors were created.

Expression of a beetle, Dendroides canadensis, antifreeze protein in Drosophila melanogaster.

Antifreeze protein 1 (DAFP-1), from the beetle Dendroides canadensis, was expressed in Drosophila melanogaster. Mean thermal hysteresis values (the difference between freezing and melting points), indicative of antifreeze protein activity, in the hemolymph of transgenic flies were found to be as high as 6.23+/-0.

The role of Drosophila ninaG oxidoreductase in visual pigment chromophore biogenesis.

We previously reported (Sarfare, S., Ahmad, S. T.

Rab11 mediates post-Golgi trafficking of rhodopsin to the photosensitive apical membrane of Drosophila photoreceptors.

In developing Drosophila photoreceptors, rhodopsin is trafficked to the rhabdomere, a specialized domain within the apical membrane surface. Rab11, a small GTPase implicated in membrane traffic, immunolocalizes to the trans-Golgi network, cytoplasmic vesicles and tubules, and the base of rhabdomeres. One hour after release from the endoplasmic reticulum, rhodopsin colocalizes with Rab11 in vesicles at the base of the rhabdomere.

The Drosophila ninaG oxidoreductase acts in visual pigment chromophore production.

The Drosophila ninaG mutant is characterized by low levels of Rh1 rhodopsin, because of the inability to transport this rhodopsin from the endoplasmic reticulum to the rhabdomere. ninaG mutants do not affect the biogenesis of the minor opsins Rh4 and Rh6. A genetic analysis placed the ninaG gene within the 86E4-86E6 chromosomal region.

Drosophila ninaB and ninaD act outside of retina to produce rhodopsin chromophore.

The Drosophila ninaB gene encodes a beta,beta-carotene-15,15'-oxygenase responsible for the centric cleavage of beta-carotene that produces the retinal chromophore of rhodopsin. The ninaD gene encodes a membrane receptor required for efficient use of beta-carotene. Despite their importance to the synthesis of visual pigment, we show that these genes are not active in the retina.