Abstract

The giant ventral photoreceptors from Limulus (horseshoe crab) provide a model system for the investigation of receptor-mediated signal transduction. In this system, light activates the IP3 transduction pathway. IP3 releases Ca2+ from the endoplasmic reticulum in Limulus photoreceptors. Injection of IP3 or Ca2+ opens ion channels in these cells. In addition, light activates a second pathway of transduction that is not Ca2+-mediated, as shown in experiments with Ca2+-depleted cells. The identity of the channels activated by light are unknown. They may be activated by cGMP and/or Ca2+. A primary goal of this investigation is to sort out the puzzling relations between the IP3 and cGMP pathways in this model system.
The specific aims of this project are: (1) to use confocal microscopy to determine the dynamics of local Ca2+ release in response to dim flashes and single photoisomerizations, (2) to determine the mechanisms of phototransduction in Ca2+-depleted photoreceptors, (3) to determine whether Ca2+ activates channels directly and (4) to sequence and localize a cGMP-gated channel in Limulus photoreceptors.

  Funding Agency

Agency
National Institute of Health (NIH)
Institute
National Eye Institute (NEI)
Type
Research Project (R01)
Project #
5R01EY007743-11
Application #
2888330
Study Section
Special Emphasis Panel (ZRG1-VISC (01))
Project Start
1988-09-01
Project End
2003-08-31
Budget Start
1999-09-01
Budget End
2003-08-31
Support Year
11
Fiscal Year
1999
Total Cost
Indirect Cost

  Institution

Name
University of Maryland College Park
Department
Zoology
Type
Schools of Earth Sciences/Natur
DUNS #
City
College Park
State
MD
Country
United States
Zip Code
20742

  Publications

Bandyopadhyay, Bidhan C; Payne, Richard (2004) Variants of TRP ion channel mRNA present in horseshoe crab ventral eye and brain. J Neurochem 91:825-35
Dabdoub, Alain; Jinks, Robert N; Wang, Youjun et al. (2003) Desensitization of the photoresponse in Limulus ventral photoreceptors by protein kinase C precedes rhabdomere disorganization and endocytosis. Vis Neurosci 20:241-8
Dabdoub, Alain; Payne, Richard; Jinks, Robert N (2002) Protein kinase C-induced disorganization and endocytosis of photosensitive membrane in Limulus ventral photoreceptors. J Comp Neurol 442:217-25
Wang, Y; Deshpande, M; Payne, R (2002) 2-Aminoethoxydiphenyl borate inhibits phototransduction and blocks voltage-gated potassium channels in Limulus ventral photoreceptors. Cell Calcium 32:209-16
Chen, F H; Baumann, A; Payne, R et al. (2001) A cGMP-gated channel subunit in Limulus photoreceptors. Vis Neurosci 18:517-26
Battelle, B A; Dabdoub, A; Malone, M A et al. (2001) Immunocytochemical localization of opsin, visual arrestin, myosin III, and calmodulin in Limulus lateral eye retinular cells and ventral photoreceptors. J Comp Neurol 435:211-25
Payne, R; Demas, J (2000) Timing of Ca(2+) release from intracellular stores and the electrical response of Limulus ventral photoreceptors to dim flashes. J Gen Physiol 115:735-48
Dabdoub, A; Payne, R (1999) Protein kinase C activators inhibit the visual cascade in Limulus ventral photoreceptors at an early stage. J Neurosci 19:10262-9
Chen, F H; Ukhanova, M; Thomas, D et al. (1999) Molecular cloning of a putative cyclic nucleotide-gated ion channel cDNA from Limulus polyphemus. J Neurochem 72:461-71
Ukhanov, K; Ukhanova, M; Taylor, C W et al. (1998) Putative inositol 1,4,5-trisphosphate receptor localized to endoplasmic reticulum in Limulus photoreceptors. Neuroscience 86:23-8

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