Photoreception and sensory transduction will be investigated in the fungus Phycomyces, in connection with its phototropism and other blue light responses. The long term objective is to understand, at the cellular and molecular levels, the processes by which a stimulus such as light is transduced into a cellular response. The unicellular sporangiophore of Phycomyces serves as a model system for primary receptor cells. The absolute operating range of 10-10:1 in light intensity and the kinetics of light and dark adaptation are similar to those observed in visual photoreceptors; in Phycomyces, the cell is naturally isolated and amenable to genetic approaches. Action spectra for phototropism and the related light-growth response will be measured to characterize the low and high intensity photosystems of the sporangiophore. Experiments with monochromatic and dichromatic continuous irradiation will be applied in a way that allows the determination of components of each photosystem and their interaction with components of the other photosystem. These experiments will also involve single and double pulse stimuli applied to dark adapted sporangiophores of wild type and mutants with altered photoreceptors; the experiments will detect any light-absorbing intermediates. The experiments will be recorded with time-lapse video equipment. Null action spectra for the light-growth response will be measured automatically on the Phycomyces tracking machine; the results will be compared with phototropic balance spectra to determine whether these responses both use the components of the photoreceptor system in the same way. The recently discovered dependence of dark adaptation on low level residual light will be pursued to help establish which photoreceptor mediates this cryptic sensitivity when the sporangiophore is unable to respond directly. System-identification experiments on the light-growth response will be continued on the tracking machine with sum-of-sinusoids test stimuli to measure the dynamic and nonlinear aspects of this response under conditions of wavelength, temperature, and intensity range. These experiments will involve both wild-type and mutant strains, and will be interpreted with analytical models for the kinetics of the photosensory transduction chain.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
2R01GM029707-05A1
Application #
3277334
Study Section
Biophysics and Biophysical Chemistry A Study Section (BBCA)
Project Start
1981-07-01
Project End
1989-06-30
Budget Start
1986-07-01
Budget End
1987-06-30
Support Year
5
Fiscal Year
1986
Total Cost
Indirect Cost
Name
Syracuse University
Department
Type
Schools of Arts and Sciences
DUNS #
City
Syracuse
State
NY
Country
United States
Zip Code
13210
Chen, X Y; Xiong, Y Q; Lipson, E D (1993) Action spectrum for subliminal light control of adaptation in Phycomyces phototropism. Photochem Photobiol 58:425-31
Sineshchekov, A V; Lipson, E D (1992) Effect of calcium on dark adaptation in Phycomyces phototropism. Photochem Photobiol 56:667-75
Ensminger, P A; Lipson, E D (1991) Action spectra of the light-growth response in three behavioral mutants of Phycomyces. Planta 184:506-9
Ensminger, P A; Chen, X Y; Lipson, E D (1990) Action spectra for photogravitropism of Phycomyces wild type and three behavioral mutants (L150, L152, and L154). Photochem Photobiol 51:681-7
Palit, A; Lipson, E D (1989) System analysis of Phycomyces light-growth response in single and double night-blind mutants. Biol Cybern 60:385-93
Galland, P; Corrochano, L M; Lipson, E D (1989) Subliminal light control of dark adaptation kinetics in Phycomyces phototropism. Photochem Photobiol 49:485-91
Galland, P; Orejas, M; Lipson, E D (1989) Light-controlled adaptation kinetics in Phycomyces: evidence for a novel yellow-light absorbing pigment. Photochem Photobiol 49:493-9
Palit, A; Pratap, P R; Lipson, E D (1989) System analysis of Phycomyces light-growth response: madC, madG, and madH mutants. Biophys J 55:519-26
Lipson, E; Pratap, P (1988) System analysis of Phycomyces light-growth response with Gaussian white noise and sum-of-sinusoids test stimuli. Ann Biomed Eng 16:95-109
Galland, P; Lipson, E D (1987) Blue-light reception in Phycomyces phototropism: evidence for two photosystems operating in low- and high-intensity ranges. Proc Natl Acad Sci U S A 84:104-8

Showing the most recent 10 out of 18 publications