Article

Drosophila visual transduction

Departments of Biological Chemistry and Neuroscience, Center for Sensory Biology, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
Trends in Neurosciences (Impact Factor: 13.56). 04/2012; 35(6):356-63. DOI: 10.1016/j.tins.2012.03.004
Source: PubMed

ABSTRACT

Visual transduction in the Drosophila compound eye functions through a pathway that couples rhodopsin to phospholipase C (PLC) and the opening of transient receptor potential (TRP) channels. This cascade differs from phototransduction in mammalian rods and cones, but is remarkably similar to signaling in mammalian intrinsically photosensitive retinal ganglion cells (ipRGCs). In this review, I focus on recent advances in the fly visual system, including the discovery of a visual cycle and insights into the machinery and mechanisms involved in generating a light response in photoreceptor cells.

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Available from: Craig Montell, Sep 19, 2015
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    • "Phototransduction in Drosophila is mediated by a G-proteincoupled phospholipase C (PLC) cascade and is an influential model for phosphoinositide signalling (Hardie, 2012; Hardie and Juusola, 2015; Katz and Minke, 2009; Montell, 2012; Yau and Hardie, 2009). The electrical response to light is mediated by two Ca 2+ permeable cation channels: transient receptor potential (TRP) and TRP-like (TRPL) (Hardie and Minke, 1992; Montell and Rubin, 1989; Phillips et al., 1992). "
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    ABSTRACT: In order to monitor phosphoinositide turnover during phospholipase C (PLC) mediated Drosophila phototransduction, fluorescently tagged lipid probes were expressed in photoreceptors and imaged both in dissociated cells, and in eyes of intact living flies. Of six probes tested, Tb(R332H) (mutant of the Tubby protein pleckstrin homology domain) was judged the best reporter for PtdIns(4,5)P2, and the P4M domain from Legionella SidM for PtdIns4P. Using accurately calibrated illumination, these indicated that only ∼50% of PtdIns(4,5)P2 and very little PtdIns4P were depleted by full daylight intensities in wild-type flies, but both were severely depleted by ∼100-fold dimmer intensities in mutants lacking Ca(2+) permeable TRP channels or protein kinase C (PKC). Resynthesis of PtdIns4P (t½ ∼12 s) was faster than PtdIns(4,5)P2 (t½ ∼40s ), but both were greatly slowed in mutants of DAG kinase (rdgA) or PtdIns transfer protein (rdgB). The results indicate that Ca(2+) and PKC-dependent inhibition of PLC is critical for enabling photoreceptors to maintain phosphoinositide levels despite high rates of hydrolysis by PLC, and suggest phosphorylation of PtdIns4P to PtdIns(4,5)P2 is the rate-limiting step of the cycle.
    Full-text · Article · Oct 2015 · Journal of Cell Science
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    • "With all the advances that have been made in elucidating the embryology and genetic control of compound eye ontogeny (e.g., Karpilow et al., 1996; Ready, 2002; Gehring, 2004; Harzsch & Hafner, 2006; Zellhof et al., 2006; Bao & Friedrich, 2009; Serb et al., 2010; Spratford & Kumar, 2013), photochemistry and transduction mechanisms (e.g., Laughlin et al., 1975; Stavenga, 1989; Terakita et al., 1996; Dorlöchter & Stieve, 1997; Kashiwagi et al., 1999; Briscoe, 2008; Montell, 2012), it is easy to overlook that even in this context there are areas that have only been poorly covered to date. Most of the molecular work to understand growth and development of the compound eye has dealt with general principles, obtained through detailed analyses of events leading to the formation of a compound eye in Drosophila (the fruit fly) and a few other species. "
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    ABSTRACT: Similarities and differences between the two main kinds of compound eye (apposition and superposition) are briefly explained before several promising topics for research on compound eyes are being introduced. Research on the embryology and molecular control of the development of the insect clear-zone eye with superposition optics is one of the suggestions, because almost all of the developmental work on insect eyes in the past has focused on eyes with apposition optics. Age and habitat related ultrastructural studies of the retinal organization are another suggestion and the deer cad Lipoptena cervi, which has a flying phase during which it is winged followed by a several months long parasitic phase during which it is wingless, is mentioned as a candidate species. Sexual dimorphism expressing itself in many species as a difference in eye structure and function provides another promising field for compound eye researchers and so is a focus on compound eye miniaturization in very small insects, especially those that are aquatic and belong to species, in which clear-zone eyes are diagnostic or are tiny insects that are not aquatic, but belong to taxa like the Diptera for instance, in which open rather than closed rhabdoms are the rule. Structures like interommatidial hairs and glands as well as corneal micro-ridges are yet another field that could yield interesting results and in the past has received insufficient consideration. Finally, the dearth of information on distance vision and depth perception is mentioned and a plea is made to examine the photic environment inside the foam shelters of spittle bugs, chrysales of pupae and other structures shielding insects and crustaceans. This article is protected by copyright. All rights reserved.
    Full-text · Article · May 2015 · Insect Science
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    • "At present, we do not understand whether light preference differences among species, or potentially within species, depend on intrinsic genetic and molecular mechanisms, or on features of life history that engender habituation and learned preferences for specific wavelengths. Within the order Diptera, molecular mechanisms underlying phototransduction and circadian rhythm have been investigated most extensively in Drosophila melanogaster, given the genetic and molecular tools available in this model organism (Montell 2012). We speculate that circadian variation in the expression of mosquito phototransduction genes may underlie diurnally variable mosquito behaviors. "
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    ABSTRACT: We understand little about photopreference and the molecular mechanisms governing vision-dependent behavior in vector mosquitoes. Investigations of the influence of photopreference on adult mosquito behaviors such as endophagy and exophagy and endophily and exophily will enhance our ability to develop and deploy vector-targeted interventions and monitoring techniques. Our laboratory-based analyses have revealed that crepuscular period photopreference differs between An. gambiae and An. stephensi. We employed qRT-PCR to assess crepuscular transcriptional expression patterns of long wavelength-, short wavelength-, and ultraviolet wavelength-sensing opsins (i.e., rhodopsin-class G-protein coupled receptors) in An. gambiae and in An. stephensi. Transcript levels do not exhibit consistent differences between species across diurnal cycles, indicating that differences in transcript abundances within this gene set are not correlated with these behavioral differences. Using developmentally staged and gender-specific RNAseq data sets in An. gambiae, we show that long wavelength-sensing opsins are expressed in two different patterns (one set expressed during larval stages, and one set expressed during adult stages), while short wavelength- and ultraviolet wavelength-sensing opsins exhibit increased expression during adult stages. Genomic organization of An. gambiae opsins suggests paralogous gene expansion of long wavelength-sensing opsins in comparison with An. stephensi. We speculate that this difference in gene number may contribute to variation between these species in photopreference behavior (e.g., visual sensitivity). © The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America.
    Full-text · Article · May 2015 · Journal of Medical Entomology
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