Visual transduction in Drosophila

Hardie, Roger C.; Raghu, Padinjat

doi:10.1038/35093002

Cited by 451 publications

(369 citation statements)

References 94 publications

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“…In mammals, CNGCs are essential components of signaling pathways involved in the olfactory and visual systems (Firestein, 2001;Hardie and Raghu, 2001). They constitute the final targets of a cascade, downstream from the receptors (odor or light receptors), and participate in the regulation of the entire response through a feedback pathway that involves other ion channels.…”

Section: Discussionmentioning

confidence: 99%

HLM1, an Essential Signaling Component in the Hypersensitive Response, Is a Member of the Cyclic Nucleotide–Gated Channel Ion Channel Family[W]

et al. 2003

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The hypersensitive response (HR) in plants is a programmed cell death that is commonly associated with disease resistance. A novel mutation in Arabidopsis, hlm1 , which causes aberrant regulation of cell death, manifested by a lesionmimic phenotype and an altered HR, segregated as a single recessive allele. Broad-spectrum defense mechanisms remained functional or were constitutive in the mutant plants, which also exhibited increased resistance to a virulent strain of Pseudomonas syringae pv tomato . In response to avirulent strains of the same pathogen, the hlm1 mutant showed differential abilities to restrict bacterial growth, depending on the avirulence gene expressed by the pathogen. The HLM1 gene encodes a cyclic nucleotide-gated channel, CNGC4 . Preliminary study of the HLM1/CNGC4 gene product in Xenopus oocytes (inside-out patch-clamp technique) showed that CNGC4 is permeable to both K ؉ and Na ؉ and is activated by both cGMP and cAMP. HLM1 gene expression is induced in response to pathogen infection and some pathogen-related signals. Thus, HLM1 might constitute a common downstream component of the signaling pathways leading to HR/resistance.

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Section: Discussionmentioning

confidence: 99%

HLM1, an Essential Signaling Component in the Hypersensitive Response, Is a Member of the Cyclic Nucleotide–Gated Channel Ion Channel Family[W]

et al. 2003

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“…These mechanisms of outputdriven and input-driven adaptation may have different biophysical origins compared with auditory receptor cells but could constitute analogous functional operations. Similarly, photoreceptors are influenced by several different adaptation mechanisms along the phototransduction pathway (Lamb and Pugh, 1992;Hardie and Raghu, 2001), and their relative contributions to light adaptation are of particular interest (Bownds and Arshavsky, 1995).…”

Section: Possible Functions Of Input-driven Adaptationmentioning

confidence: 99%

Input-Driven Components of Spike-Frequency Adaptation Can Be UnmaskedIn Vivo

Gollisch¹,

Herz²

2004

J. Neurosci.

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Spike-frequency adaptation affects the response characteristics of many sensory neurons, and different biophysical processes contribute to this phenomenon. Many cellular mechanisms underlying adaptation are triggered by the spike output of the neuron in a feedback manner (e.g., specific potassium currents that are primarily activated by the spiking activity). In contrast, other components of adaptation may be caused by, in a feedforward way, the sensory or synaptic input, which the neuron receives. Examples include viscoelasticity of mechanoreceptors, transducer adaptation in hair cells, and short-term synaptic depression. For a functional characterization of spike-frequency adaptation, it is essential to understand the dependence of adaptation on the input and output of the neuron. Here, we demonstrate how an input-driven component of adaptation can be uncovered in vivo from recordings of spike trains in an insect auditory receptor neuron, even if the total adaptation is dominated by output-driven components. Our method is based on the identification of different inputs that yield the same output and sudden switches between these inputs. In particular, we determined for different sound frequencies those intensities that are required to yield a predefined steady-state firing rate of the neuron. We then found that switching between these sound frequencies causes transient deviations of the firing rate. These firing-rate deflections are evidence of input-driven adaptation and can be used to quantify how this adaptation component affects the neural activity. Based on previous knowledge of the processes in auditory transduction, we conclude that for the investigated auditory receptor neurons, this adaptation phenomenon is of mechanical origin.

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“…Largely because of its molecular genetic potential, Drosophila has become an important model system not only for phototransduction but for inositol lipid signaling in general (1)(2)(3). The generally accepted mechanism of excitation conforms to the canonical phosphoinositide cascade (see Fig.…”

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confidence: 99%

Rescue of Light Responses in the Drosophila “Null” Phospholipase C Mutant, norpA, by the Diacylglycerol Kinase Mutant, rdgA, and by Metabolic Inhibition

Hardie

Martín

Chyb³

et al. 2003

Journal of Biological Chemistry

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Light responses in Drosophila are reportedly abolished in severe mutants of the phospholipase C (PLC) gene, norpA. However, on establishing the whole-cell recording configuration in photoreceptors of the supposedly null allele, norpA P24 , we detected a small (ϳ15 pA) inward current that represented spontaneous light channel activity. The current decayed during ϳ20 min, after which tiny residual responses (<2 pA) were elicited by intense flashes. Both spontaneous currents and light responses appeared to be mediated by residual PLC activity, because they were enhanced by impairing diacylglycerol (DAG) kinase function by mutation (rdgA) or by restricting ATP but were reduced or abolished by a mutation of the PLC-specific G q ␣ subunit. It was reported recently that metabolic inhibition activated the light-sensitive transient receptor potential and transient receptor potential-like channels, even in norpA P24 , leading to the conclusion that this action was independent of PLC (Agam, K., von Campenhausen, M., Levy, S., Ben-Ami, H. C., Cook, B., Kirschfeld, K., and Minke, B. (2000) J. Neurosci. 20, 5748 -5755). However, we found that channel activation by metabolic inhibitors in norpA P24 was strictly dependent on the residual PLC activity underlying the spontaneous current, because the inhibitors failed to activate any channels after the spontaneous current had decayed. By contrast, polyunsaturated fatty acids invariably activated the channels independently of PLC. The results strongly support the obligatory requirement for PLC and DAG in Drosophila phototransduction, suggest that activation by metabolic inhibition is primarily because of the failure of diacylglycerol kinase, and are consistent with the proposal that polyunsaturated fatty acids, which are potential DAG metabolites, act directly on the channels.

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Visual transduction in Drosophila

Cited by 451 publications

References 94 publications

HLM1, an Essential Signaling Component in the Hypersensitive Response, Is a Member of the Cyclic Nucleotide–Gated Channel Ion Channel Family[W]

HLM1, an Essential Signaling Component in the Hypersensitive Response, Is a Member of the Cyclic Nucleotide–Gated Channel Ion Channel Family[W]

Input-Driven Components of Spike-Frequency Adaptation Can Be UnmaskedIn Vivo

Rescue of Light Responses in the Drosophila “Null” Phospholipase C Mutant, norpA, by the Diacylglycerol Kinase Mutant, rdgA, and by Metabolic Inhibition

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