The characteristics of chemically induced noise inMusca photoreceptors

Minke, Baruch; Stephenson, Robert S.

doi:10.1007/bf00610727

Cited by 38 publications

(25 citation statements)

References 35 publications

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“…This property allows measuring of the physiological implication of G q ␣ movements in vivo at the highest resolution. Photon absorption by rhodopsin in fly photoreceptors activates either one (Scott et al, 1995) or few G q ␣ protein molecules (Minke and Stephenson, 1985;Hardie et al, 2002), which subsequently activates PLC (Devary et al, 1987;Bloomquist et al, 1988) and leads, in a still unclear way, to the generation of a single-photon response called a quantum bump (Yeandle and Spiegler, 1973). The bumps sum to produce the macroscopic response to light (Dodge et al, 1968;Barash and Minke, 1994).…”

Section: Introductionmentioning

confidence: 99%

Translocation of G_qα Mediates Long-Term Adaptation inDrosophilaPhotoreceptors

Frechter

Elia²,

Tzarfaty³

et al. 2007

J. Neurosci.

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Light adaptation is a process that enables photoreceptor cells to operate over a wide range of light intensities without saturation. In invertebrate photoreceptors, fast adaptation is mediated by a Ca 2ϩ -dependent negative-feedback mechanism, which mainly affects the terminal steps of the cascade. Therefore, the response to each photon is smaller as light intensity increases, accommodating both high sensitivity and a vast dynamic range. Here, we describe a novel type of adaptation, which is mediated by one of the first steps in the phototransduction cascade affecting the sensitivity to absorbed photons. Long exposure to light resulted in dramatic reduction in the probability of each absorbed photon to elicit a response, whereas the size and shape of each single photon response did not change. To dissect the molecular mechanism underlying this form of adaptation we used a series of Drosophila mutants. Genetic dissection showed a pivotal role for light-induced translocation of G q ␣ between the signaling membrane and the cytosol. Biochemical studies revealed that the sensitivity to light depends on membrane G q ␣ concentration, which was modulated either by light or by mutations that impaired its targeting to the membrane. We conclude that long-term adaptation is mediated by the movement of G q ␣ from the signaling membrane to the cytosol, thereby reducing the probability of each photon to elicit a response. The slow time scale of this adaptation fits well with day/night light intensity changes, because there is no need to maintain single photon sensitivity during daytime.

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Section: Introductionmentioning

confidence: 99%

Translocation of G_qα Mediates Long-Term Adaptation inDrosophilaPhotoreceptors

Frechter

Elia²,

Tzarfaty³

et al. 2007

J. Neurosci.

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“…Fig. 5 (18), and GTP analogs induce membrane depolarization in Musca photoreceptors (17). Lightdependent GTP binding and increased inositolphospholipid turnover are exhibited by fly (Musca and Drosophila) eye membranes (36).…”

Section: Resultsmentioning

confidence: 96%

“…The high degree of conservation of mammalian G proteins (16) and the biochemical evidence for the existence of G proteins in insects (17)(18)(19) and other invertebrates (20,21) prompted us to search for homologous genes in Drosophila melanogaster. We chose Drosophila, a metazoan organism amenable to genetic manipulation, to better understand the functions of these ubiquitous proteins.…”

mentioning

confidence: 99%

Cloning of a Drosophila melanogaster guanine nucleotide regulatory protein beta-subunit gene and characterization of its expression during development.

Yarfitz

Provost

Hurley

1988

Proc. Natl. Acad. Sci. U.S.A.

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A Drosophila melanogaster gene encoding a protein with >80% sequence identity to the .3 subunits of mammalian guanine nucleotide-binding regulatory proteins (G proteins) has been cloned. The gene, which was mapped to 13F on the X chromosome by in situ hybridization, was cloned from a Drosophila genomic library by using a bovine transducin (20,21) prompted us to search for homologous genes in Drosophila melanogaster. We chose Drosophila, a metazoan organism amenable to genetic manipulation, to better understand the functions of these ubiquitous proteins. Mutants with abnormalities in signal-transduction processes may result from mutations in G-protein genes. Potential phenotypes of Gprotein mutations include membrane polarization (22) and sensory (23) and learning (24)

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“…A variety of chemical agents, such as hydrolysis-resistant GTP analogues, fluoride, vanadate, and metabolic inhibitors, are known to induce discrete voltage fluctuations (bumps) of the membrane potential in invertebrate photoreceptors in the dark (Fein andCorson, 1979, 1981;Payne, 1981Payne, , 1982Bolsover and Brown, 1982;Corson and Fein, 1983;Minke and Stephenson, 1985;Stern et al, 1985). Metabolites generated by inositol phospholipid hydrolysis, such as 1,4,5 inositol trisphosphate (InsP3), are very effective in exciting and adapting invertebrate photoreceptors (Fein et al, 1984;Brown et al, 1984;Payne et al, 1986a, b;Devary et al, 1987).…”

Section: Introductionmentioning

confidence: 99%

“…Fand the GTP analogues induce bumps similar in shape to those caused by light, but with amplitudes about five times smaller. This suggests a relatively small gain in the activation of the guanine nucleotide-binding protein (G protein) by rhodopsin (Limulus: Fein andCorson, 1979, 1981;Bolsover and Brown, 1982; Musca: Minke and Stephenson, 1985).…”

Section: Introductionmentioning

confidence: 99%

Chemical excitation and inactivation in photoreceptors of the fly mutants trp and nss.

Süß

Barash

Stavenga

et al. 1989

The Journal of General Physiology

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The Drosophila and Lucilia photoreceptor mutants, trp and nss, respond like wild-type flies to a short pulse of intense light or prolonged dim light; however, upon continuous intense illumination, the trp and nss mutants are unable to maintain persistent excitation. This defect manifests itself by a decline of the receptor potential toward baseline during prolonged intense illumination with little change in the shape or amplitude of the quantal responses to single photons (quantum bumps). Previous work on the trp and ms mutants suggests that a negative feedback loop may control the rate of bump production. Chemical agents affecting different steps of the phototransduction cascade were used in conjunction with light to identify a possible branching point of the feedback loop and molecular stages which are affected by the mutation. Fluoride ions, which in the dark both excite and adapt the photoreceptors of wild-type flies, neither excite nor adapt the photoreceptors of the trp and nss mutants. The hydrolysis-resistant analogue, GTP~,S, which excites the photoreceptors of wild-type flies, resulting in noisy depolarization, markedly reduces the light response of both mutant flies. Intracellular recordings revealed, however, that the inhibitory effect of GTP~?S on the ms mutant was accompanied neither by any significant depolarization nor by an increase in the noise, and thus was very different from the effect of a dim background light. The combination of inositol trisphosphate and diphosphoglycerate (InsP s + DPG), which efficiently excites the photoreceptors of wild-type Lucilia, also excites the photoreceptors of nss Lucilla mutant. The InsPs+DPG together act synergistically with light to accelerate the decline of the response to light in the mutant flies. These results suggest that the fly phototransduction pathway involves a feedback regulatory loop, which branches subsequent to InsP s production and regulates guanine nucleotide-binding protein (G protein)-phospholipase C activity.

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The characteristics of chemically induced noise inMusca photoreceptors

Cited by 38 publications

References 35 publications

Translocation of G_qα Mediates Long-Term Adaptation inDrosophilaPhotoreceptors

Translocation of G_qα Mediates Long-Term Adaptation inDrosophilaPhotoreceptors

Cloning of a Drosophila melanogaster guanine nucleotide regulatory protein beta-subunit gene and characterization of its expression during development.

Chemical excitation and inactivation in photoreceptors of the fly mutants trp and nss.

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The characteristics of chemically induced noise inMusca photoreceptors

Cited by 38 publications

References 35 publications

Translocation of Gqα Mediates Long-Term Adaptation inDrosophilaPhotoreceptors

Translocation of Gqα Mediates Long-Term Adaptation inDrosophilaPhotoreceptors

Cloning of a Drosophila melanogaster guanine nucleotide regulatory protein beta-subunit gene and characterization of its expression during development.

Chemical excitation and inactivation in photoreceptors of the fly mutants trp and nss.

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Translocation of G_qα Mediates Long-Term Adaptation inDrosophilaPhotoreceptors

Translocation of G_qα Mediates Long-Term Adaptation inDrosophilaPhotoreceptors