very important, especially the comparison of vertebrate and invertebrate transduction mechanisms. The workshop was very successful and the outcome of the discussions proved it worth the effort. To no small extent has that success been made possible by Dr. Silke Bernhard who with a combination of authority and charm together with her extremely efficient and dedicated staff organized this workshop, providing the conditions and framework for a scientific debate of outstanding quality in a friendly and pleasant atmosphere. The great majority of participants were also very committed to making this workshop successful. Besides the reports of the four discussion groups, this publication contains the background papers which were revised by the authors partly as a result of suggestions of some participants. I hope this book will give a fair overview of the state of our knowledge of research in visual transduction. It was a pleasure to edit, especially because of the friendly and very efficient commitment of K. Geue, J. Lupp, and A. Eckert and the cooperativeness of most of the contributors. Particularly I would like to acknowledge gratefully the extensive efforts and patience of the four rapporteurs, M.L. Applebury, W.H. Miller, W.G. Owen, and E.N. Pugh, Jr., in compiling, writing, and revising the group reports. REFERENCES (1) Altman, J. 1985. Sensory transduction, new visions in photoreception. Nature 313: 264-265. (2) Hagins, W.A. 1972. The visual process: Excitatory mechanisms in the primary receptor cells. Ann. Rev. Biophys. Bioeng. 1: 131-158.

Inhalt

The Biosynthetic, Functional, and Evolutionary Implications of the Structure of Rhodopsin.- Activation of Visual Pigment: Chromophore Structure and Function.- Interaction of Photoactivated Rhodopsin with Photoreceptor Proteins: The cGMP Cascade.- Evidence for a Role of Messenger Substances in Phototransduction.- Evaluation of Internal Transmitter Candidates: Ca.- Significance of Changes in Intracellular Ca2+ for the Mechanism of Signal Transduction in Vertebrate Rod Cells.- Evaluation of Rod Internal Transmitter Candidates: Cyclic GMP.- Properties of Cytoplasmic Transmitters of Excitation in Vertebrate Rods and Evaluation of Candidate Intermediary Transmitters.- Changes in Protein Phosphorylation and Nucleoside Triphosphates during Phototransduction - Physiological Correlates.- The Light-induced Conductance Change in the Vertebrate Rod.- Properties of the Light-dependent Membrane Conductances in Invertebrate Photoreceptors.- Bumps, the Elementary Excitatory Responses of Invertebrates.- Calcium and Light Adaptation in Invertebrate Photoreceptors.- Photopigment-dependent Adaptation in Invertebrates - Implications for Vertebrates.- Photoreceptor Adaptation - Vertebrates.- Turnover of Vertebrate Photoreceptor Membranes.- Turnover of Photoreceptor Membrane and Visual Pigment in Invertebrates.- Quantitative Models of Phototransduction.- Experimental Results and Physical Ideas towards a Model for Quantum Bumps in Photoreceptors.- Potentials and Limitations of Noise Analysis of Light-induced Conductance Changes in Photoreceptors.- Molecular Genetic Approach to the Study of Phototransduction in Drosophila.- Triggering and Amplification Group Report.- Internal Messengers Group Report.- Light-sensitive Channels, Pumps, and Carriers Group Report.- Adaptation Group Report.- List of Participants with Fields of Research.- Author Index.