Rapid progress has been made in our understanding of the molecular mechanisms of cell growth and oncogenesis during the past decade. This book comprises recent results on the regulation of cell growth in normal and neoplastic tissues by growth factors including hormones, and by the activation and inactivation of oncogenes and tumor suppressor genes, respectively. Special attention has been given to the presentation of the frequently neglected close correlation between changes in signal transduction and metabolism pathways during oncogenesis.

cytochemical techniques (ICC) which provide a useful adjunct to investigations by immunoblotting. A particular advantage of a cytochemical approach to the investiga tion of mitochondrial disorders is that it allows the mosaic distribution of certain of these defects to be detected, whereas the tissue homogeniza tion involved in conventional enzyme assays or immunoblotting precludes this. A further advantage of MEA or ICC is that only small amounts of tissue are needed, which is important since many of the affected patients are infants or small children. The main aim of this communica tion is to outline ways in which these techniques can be used in the diagnosis and further investigation of mitochondrial disorders. Reference will be made not only to those situations in which MEA and ICC offer advantages over standard enzyme asays and immunoblotting but also to contexts in which the reverse applies. 4. 2 MATERIALS AND METHODS Muscle biopsies for cytochemical investigation were snap-frozen using isopentane cooled to - 150 DegreesC in liquid nitrogen. Samples were stored in heat-sealed polythene packets in the vapour phase of liquid nitrogen containers. 4. 2. 1 Microphotometric enzyme assays Frozen sections 8 Jlm thick were cut using a Reichert-J ung Frigocut cryostat microtome equipped with motor-driven cutting action to maintain maximal reproducibility of section thickness. Sections were picked up on microscope slides and air-dried for 15 min at room temperature.

This volume is based on the proceedings of an International Symposium on "Cytochrome Systems: Molecular Biology and Bioenergetics" that was held at Selva di Fasano near Bari, Italy, between April 7 and 11,1987. It contains papers covering the subjects discussed at the Symposium, contributed both by participants of the meeting and by some invited speakers who were not able to attend. The aim of the Symposium was to bring together experts in various rese arch strategies currently being applied to the study of cytochrome systems, including molecular genetics, protein chemistry, enzymology of electron transfer and protonmotive activity in energy-transducing biological mem branes. Because of the high degree of complexity of cytochrome systems and the increasing sophistication in recent years of the different experimen tal approaches, there has been a growing specialization - sometimes even a tendency to "over-specialization" - among scientists working in this field. This in itself seemed to justify a meeting where representatives of various disciplines could exchange their results and discuss their conclusions. In addition, and perhaps even more importantly, it was felt that meetings of this kind provide an opportunity for a "cross-fertilization" of approaches and ideas among representatives of various fields of science. The present meeting proved to be an ample illustration of the success of such an inter action.

Rapid progress has been made in our understanding of the molecular mechanisms of cell growth and oncogenesis during the past decade. This book comprises recent results on the regulation of cell growth in normal and neoplastic tissues by growth factors including hormones, and by the activation and inactivation of oncogenes and tumor suppressor genes, respectively. Special attention has been given to the presentation of the frequently neglected close correlation between changes in signal transduction and metabolism pathways during oncogenesis.

cytochemical techniques (ICC) which provide a useful adjunct to investigations by immunoblotting. A particular advantage of a cytochemical approach to the investiga tion of mitochondrial disorders is that it allows the mosaic distribution of certain of these defects to be detected, whereas the tissue homogeniza tion involved in conventional enzyme assays or immunoblotting precludes this. A further advantage of MEA or ICC is that only small amounts of tissue are needed, which is important since many of the affected patients are infants or small children. The main aim of this communica tion is to outline ways in which these techniques can be used in the diagnosis and further investigation of mitochondrial disorders. Reference will be made not only to those situations in which MEA and ICC offer advantages over standard enzyme asays and immunoblotting but also to contexts in which the reverse applies. 4. 2 MATERIALS AND METHODS Muscle biopsies for cytochemical investigation were snap-frozen using isopentane cooled to - 150 DegreesC in liquid nitrogen. Samples were stored in heat-sealed polythene packets in the vapour phase of liquid nitrogen containers. 4. 2. 1 Microphotometric enzyme assays Frozen sections 8 Jlm thick were cut using a Reichert-J ung Frigocut cryostat microtome equipped with motor-driven cutting action to maintain maximal reproducibility of section thickness. Sections were picked up on microscope slides and air-dried for 15 min at room temperature.

This book consists of a series of reviews on selected topics within the rapidly and vastly expanding field of membrane biology. Its aim is to highlight the most significant and important advances that have been made in recent years in understanding the structure, dynamics, and functions of cell membranes. The progress that is being made in research in this field is due to the application of integrated experimental ap- proaches, utilizing sophisticated and novel techniques in molecular biology, cell biology, biophysics and biochemistry. Due to the advances made, many problems have been or are being solved at the molecular level. With the help of an Editorial Advisory Board consisting of Jean-Pierre Changeux (Paris), Paolo Comoglio (Torino), Rainer Jaenicke (Regens- burg), Sten Orrenius (Stockholm), Lorenzo Pinna (Padova), Konrad Sandhoff (Bonn), and Gottfried Schatz (Basel), we have selected a number of topics in areas in which progress has been particularly rapid, and have invited internationally acknowledged experts in the field to review these topics. The areas covered in this monograph are: 1) Signal transduction; 2) Membrane traffic: Proteins and lipids; 3) Bioenergetics: Energy transfer and membrane transport; 4) Cellular ion homeostasis; 5) Growth factors and adhesion molecules; 6) Structural analysis of mem- brane proteins; and 7) Membranes and disease.

The Expert Committee on Biomaterials and Biotechnology for the European and the North American Region was founded by the General Assembly of UNESCO at its 21st Session, in 1981. The Committee comprises a Coordinating Group and four working Groups, defined in the following scientific areas: Group I Proteins: source, structure and function. Group II Nucl~ic acids: the hereditary materials. Group III Im~une materials and mechanisms. Membranes and transport in biosystems. Group IV In fulfilment of one of the objectives of the Committee, which have been adopted by the General Assembly of UNESCO in 1981, namely the intensification of the exchange of scientific information on biomaterials and biotechnology, working Group IV organized an international workshop on Ion Interactions in Energy Transport Systems, which was convened in Athens, Greece, from 8 to 12 April, 1985. Scientific papers presented at that workshop make up the chapters presented in this volume. The present volume focusses on natural and artificial membranes that are involved in energy transduction. Several chapters are devoted to membranes and membrane components that convert and utilize light, such as the thylakoid membrane of oxygenic photosynthetic organisms (eukaryotic and prokaryotic), the chromatophore membrane of nonoxygenic photosynthetic bacteria and the purple membrane of the halophilic bacteria. Other systems examined include the mitochondrial membranes and their adenine nucleotide carrier, the plasma membrane of animal cells, and lipid bilayer vesicles, either reconstituted or not, with enzymes.