SYSTEM ANALYSIS OF PHYCOMYCES PHOTORESPONSES

将在真菌中研究光接收和感觉转导。 藻类真菌与其向光性和其他蓝光的关系 回应。长期目标是理解，在细胞和 分子水平，刺激的过程，如光 转化为细胞反应。黄曲霉的单细胞孢子囊 藻霉是初级受体细胞的模型系统。这个 光强为10-10：1的绝对工作范围和动力学 明暗适应与在视觉上观察到的相似 光感受器；在藻类中，细胞是自然分离的和顺从的 遗传方法。向光性的作用光谱及其相关的 将测量光生长响应来表征低和高 孢子囊的光系统强度。实验： 单色和双色连续照射将应用于 一种允许确定每个光系统的组件的方法 它们与另一个光系统的组件相互作用。这些 实验还将涉及将单脉冲和双脉冲刺激应用于 野生型和突变体变异型暗适应孢子囊 光感受器；实验将检测到任何光吸收 中间体。这些实验将用延时视频记录下来 设备。光生长响应的零作用光谱将是 在Phycomyces跟踪器上自动测量；结果将 与光致平衡光谱进行比较，以确定这些 两种反应都使用相同的光感受器系统的组件 道路。最近发现的暗适应对低水平的依赖 残余光将被用来帮助确定哪个感光器 当孢子囊不能 直接回应。光生长的系统辨识实验 响应将在跟踪机器上用正弦和继续进行 测试刺激以测量该响应的动态和非线性方面 在波长、温度和强度范围内。这些 实验将涉及野生型和突变菌株，并将 用光敏动力学的解析模型进行解释 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.