Biophysics Of Photoreception Molecular And Phototransductive Events

This is the first volume of new book series on biophysics and biocybernetics, initiated by the Istituto Italiano per gli Studi Filosofici.A main problem in biophysics is the interaction of light information with functional living structures, in order to shape the organism's behaviour. Although the processes of photoreception and phototransduction are articulated in various ways in different living beings — as it is seen in the subdivision of the topics in this volume on microorganisms, invertebrates, and vertebrates — general ways of light signal reception and transduction through light energy, i.e., photosensitive molecule interactions, could be observed. Highly sophisticated advanced techniques are employed in this research field.

Brings together key new results of interdisciplinary collaborations among various research fields on rhodopsin including the photoreceptive mechanism of rhodopsins, the molecular mechanism of the visual transduction process, visual processes in the retina and other transduction processes in the retina and brain. The structures of the rhodopsin molecule are studied in the fields of protein chemistry, molecular biology, organic chemistry and structural biology; the ultra fast reactions of the retinal protein are studied in physics, biophysics, physical chemistry, organic chemistry and photobiology; the phototransduction in retinal proteins and visual cells are studied in biophysics, biochemistry, biophysical chemistry and photobiology; and the localization in the tissues is studied in anatomy and histochemistry. The diversity of visual systems in various animals is studied in zoology and comparative biochemistry.

This volume contains the lectures given at the NATO Advanced Study Institute on "Biophysics of Photoreceptors and Photomovements in Microorganisms" held in Tir renia (Pisa), Italy, in September 1990. The Institute was sponsored and mainly funded by the Scientific Affairs Division of NATO; the Physical Science Committee and the Institute of Biophysics of National Research Council of Italy also supported the School and substantially contributed to its success. It is our pleasant duty to thank these institu tions. Scientists from very different backgrounds contributed to the understanding of this fast developing field of research, which has seen considerable progress during the last years. The areas of expertise ranged from behavioral sciences, supported by sophi sticated techniques such as image analysis or laser light scattering, to spectroscopy, ap plied, in different time domains, to the study of the primary photoreactions, to electro physiology, biochemistry or molecular biology, with the aim of analyzing the various steps of the transduction chains and how they control the motor apparatus of the cells. The organisms studied covered a wide range, from bacteria to algae, fungi and other eukaryotes. Thus, the ASI represented a successful opportunity for carrying on and imple menting an interdisciplinary approach to the study of the biophysical basis of photore ception and photosensory transduction in aneural organisms, with special attention to the basic phenomena and the underlying molecular events. We hope that this book has caught the spirit in which the ASI was conceived.

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.

This book is a sequel on the topics of photoreception and phototransduction covered by Volume I of the series (Biophysics of Photoreception: Molecular and Phototransductive Events), adding the analysis of two other modalities of sensory reception and transduction — the chemical and mechanical ones, which are phylogenetically older. This characterization results not in a succession of three different and uncorrelated moments, but in a fruitful confrontation between experts which usually act separately and in an integration between various particular knowledges. This approach highlights the basic strategies common to different sensory modalities and specializations, as well as the ecological adaptations of each of them.

This book deals with the mechanism of signal transduction in vertebrate and invertebrate photoreceptors. It contains contributions on the structure and function of rhodopsin or other G-coupled receptors, on the regulation of second messengers by enzyme cascade, the role of Ca2+ in light adaptation, control of ionic channels in photoreceptor cells.

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.

This book is a sequel on the topics of photoreception and phototransduction covered by Volume I of the series (Biophysics of Photoreception: Molecular and Phototransductive Events), adding the analysis of two other modalities of sensory reception and transduction -- the chemical and mechanical ones, which are phylogenetically older. This characterization results not in a succession of three different and uncorrelated moments, but in a fruitful confrontation between experts which usually act separately and in an integration between various particular knowledges. This approach highlights the basic strategies common to different sensory modalities and specializations, as well as the ecological adaptations of each of them.