This book collects all the lectures presented during the NATO Advanced Study Institute on "Photoreception and Sensory Transduction in Aneura1 Organisms," held in Villa Le Pianore (Versi1ia, Italy), September 3-14, 1979. In order to publish the lectures in the shortest possible time, we had to make the decision not to include the free communications, the informal seminars, and the panel discussions, notwithstanding their very high scientific level and interest. Only the final panel discussion has been summarized by Prof. W. Haupt (whose effort we gratefully acknowledge), because it gives a comprehensive view of the state of the art in this field. The ASI was intended to be a high-level course, characterized by an interdisciplinary approach to the problem of photoreception and photosensory physiology in aneural organisms, bringing together scientists from different fields and specializations. We hope that these characteristics are reflected in the content of the book, which is meant to be both an advanced textbook for researchers and students entering the field and a critical overview of the problems of photosensory transduction in aneura1 organisms. The topics pre sented range from a phenomenological description of the different photomotile responses in various microorganisms to a discussion of the molecular processes involved in the primary events of photo reception as well as in the subsequent steps of the transduction chain.

Inhalt
Sensory Transduction in Aneural Organisms.- to Optical Stimuli: Physical Properties of the Light Beam.- Photomotile Responses in Flagellates.- Photomotile Responses in Gliding Organisms and Bacteria.- Phototropism of Lower Plants.- Experimental Determination and Measurement of Photoresponses.- The Photoreceptive Apparatus of Flagellated Algal Cells: Comparative Morphology and Some Hypotheses on Functioning.- Localization and Orientation of Photoreceptor Pigments.- Identification and Spectroscopic Characterization of Photoreceptor Pigments.- Primary Photophysical and Photochemical Reactions: Theoretical Background and General Introduction.- Molecular Aspects of Photoreceptor Function: Carotenoids and Rhodopsins.- Molecular Aspects of Photoreceptor Function: Phytochrome.- Molecular Aspects of Photoreceptor Function in Stentor Coeruleus.- Possible Photoregulation by Flavoproteins.- Bluelight Reception and Flavin Photochemistry.- Basic Concepts in Bioenergetics.- Properties of the Photosynthetic Membrane.- Comparative Discussion of Photoreception in Lower and Higher Organisms. Structural and Functional Aspects.- Photosensory Transduction Chains in Eucaryotes.- Photosensory Transduction Chain in Procaryotes.- Sensory Transduction in Phototropism: Genetic and Physiological Analysis in Phycomyces.- Panel Discussion Sensory Transduction and Photobehaviors: Final Considerations and Emerging Themes.- Participants.