SYSTEM ANALYSIS OF PHYCOMYCES PHOTORESPONSES

光感受和感觉转导将在真菌中进行研究 藻蓝蛋白，与其向光性和其他蓝光有关 应答 长期目标是了解，在细胞和 分子水平上，刺激，如光， 转化为细胞反应。 单细胞孢子囊柄 Phycommony作为初级受体细胞的模型系统。 的 绝对操作范围为10-10：1的光强度和动力学 光适应和暗适应与在视觉中观察到的相似。 光感受器;在藻细胞中，细胞是天然分离的， 基因方法。 向光性的作用光谱及相关的 将测量光生长响应以表征低和高 增强子囊柄的光系统。 实验 单色和双色连续照射将应用于 一种可以确定每个光系统组成的方法， 它们与其他光系统成分的相互作用。 这些 实验还将涉及施加到 野生型和突变体的暗适应孢子囊体 光感受器;实验将检测任何吸收光的物质 中间体的 这些实验将用延时录像记录下来 设备. 光生长响应的吸收光谱将是 在Phycommony跟踪仪上自动测量;结果将 与向光平衡光谱进行比较，以确定这些 反应都使用光感受器系统的组件， 路上了 最近发现的暗适应对低能级的依赖性 将追踪残余光以帮助确定哪个光感受器 当孢子囊梗不能 直接回答。 光生长的系统辨识实验 在跟踪机上继续响应，并采用正弦曲线和 测试刺激以测量这种反应的动态和非线性方面 在波长、温度和强度范围的条件下。 这些 实验将涉及野生型和突变株，并将 用光敏反应动力学的分析模型来解释， 转导链

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.