I propose to investigate the mechanism that underlies the prolonged depolarizing afterpotentials (PDAs) present in many invertebrate photoreceptors. The questions I seek to answer are whether the PDA, like the light coincident receptor potential (LCRP), is a summation of bumps, and, if so, whether the bumps that constitute the PDA are different from those that make up the LCRP. I will also compare PDA bumps and LCRP bumps with those induced by chemical agents such as fluoride and non-hydrolyzable GTP analogs, and investigate the interaction of the different types of bumps with one another. I intend further to describe the post-stimulus timecourse of the PDA in terms of its underlying bump processes. A number of PDA-defective mutants of Drosophila have been previously isolated, and I will analyze them, as well as wild-type Drosophila and Musca, in the terms outlined above. In this way I hope to define the sequence of events leading to bump generation during PDA or LCRP, and which step or steps in this sequence have been affected in each mutant. It is my intention to synthesize these findings in the form of a quantitative model of the phototransduction process.

Agency
National Institute of Health (NIH)
Institute
National Eye Institute (NEI)
Type
Research Project (R01)
Project #
5R01EY004186-06
Application #
3258708
Study Section
Visual Sciences A Study Section (VISA)
Project Start
1981-09-01
Project End
1988-06-30
Budget Start
1986-09-30
Budget End
1988-06-30
Support Year
6
Fiscal Year
1986
Total Cost
Indirect Cost
Name
Wayne State University
Department
Type
Schools of Arts and Sciences
DUNS #
City
Detroit
State
MI
Country
United States
Zip Code
48202
Giovannucci, D R; Stephenson, R S (1999) Identification and distribution of dietary precursors of the Drosophila visual pigment chromophore: analysis of carotenoids in wild type and ninaD mutants by HPLC. Vision Res 39:219-29
Stephenson, R S (1988) On the interpretation of voltage noise in small cells. J Neurosci Methods 26:141-9
Stephenson, R S; Overbeck, G W (1986) An improved microelectrode resistance meter. J Neurosci Methods 17:335-42