Influenza continues to be one of the major epidemic diseases of man and is, in fact, his only remaining pandemic disease (BEVERIDGE, 1969). This is largely because influenza virus undergoes extreme antigenic variation, the mechanism of which is still poorly understood. Two kinds of antigenic variation occur in influenza viruses, antigenic drift and major antigenic shifts; both involve chan ges in the hemagglutinin and neuraminidase antigens on the surface of the virus. Antigenic drift, which involves gradual changes in the surface antigens of influenza virus, is thought to result from the selection by an immune popula tion of mutant virus particles with altered antigenic determinants. These mutants therefore possess a growth advantage in the presence of antibody (FRAN CIS and MAASSAB, 1965; ARCHETTI and HORSFALL, 1950; HAMRE et aI., 1958). It has been shown that antigenic mutants isolated in vitro by selection with antibody have changes in amino acid sequence in the polypeptides of the hem agglutinin subunits (LAVER and WEBSTER, 1968) and it is likely that antigenic drift in the neuraminidase occurs by the same mechanism.

This volume includes contributions by the leading experts in the field of yeast aging. Budding yeast (Saccharomyces cerevisiae) and other fungal organisms provide models for aging research that are relevant to organismic aging and to the aging processes occurring in the human body. Replicative aging, in which only the mother cell ages while the daughter cell resets the clock to zero is a model for the aging of stem cell populations in humans, while chronological aging (measured by survival in stationary phase) is a model for the aging processes in postmitotic cells (for instance, neurons of the brain). Most mechanisms of aging are studied in yeast. Among them, this book discusses: mitochondrial theories of aging, emphasizing oxidative stress and retrograde responses; the role of autophagy and mitophagy; the relationship of apoptosis to aging processes; the role of asymmetric segregation of damage in replicative aging; the role of replication stress; and the role of the cytoskeleton in aging. Modern methods of yeast genetics and genomics are described that can be used to search for aging-specific functions in a genome-wide unbiased fashion. The similarities in the pathology of senescence (studied in yeast) and of cancer cells, including genome instability, are examined.

th st On June 20 and 21 1985 the third workshop on "Azospirillum: Geneties, Physiology, Eeology" took place at the University of Bayreuth, West Germany, organized by the geneties department. There were about 80 partieipants, who eame from German research institutions, from other European eountries, from India, Egypt, North and South America. The former workshops had taken place in Bayreuth too in 1981 and 1983 respeetively, henee the organizers eould draw on the experienees then obtained. Azospirilla have, during the past 12 years, found an ever inereasing seientifie interest, beeause first, these soil baeteria earry the genetie information for binding moleeular nitrogen from the air, and second, they live in elose vieinity to the roots of grain erops and forage grasses. By exploi tation of these two properties, it is hoped to develop inoeulation proeedures in soils poor in nitrogen. The reports on the first afternoon foeussed, as aresult of the Bayreuth research interest, on genetie approaehes.

This book brings together various contributions aimed at the elucida tion of the structural and functional organization of the bacterial nucleoid. Most of these papers, spanning the fields of physical chemistry through biochemistry to genetics, were presented at the session on bac terial chromatin during the Symposium "Selected topics on chromatin structure and function" held at the University of Camerino, Italy, at the end of May 1985. Times when the bacterial DNA was regarded as "naked" or, at most, complexed with polyamines, and when the absence of histones and organized chromatin was considered to be a distinct feature of the pro karyotic cell, now appear remote. Our concepts of how DNA is packaged in bacteria are changing rapidly. Studies on the structure of the bacterial nucleoid are not new. Recently, however, investigations in this field have flourished again, leading to some important contributions such as the elucidation of the three-dimensional structure of what appears to be the major protein constituent of the bacterial nucleoid or the development of methods to titrate the extent of DNA supercoiling within the bacterial cell."

This book is a collection of data on the tenacity in the environment of bacteria and some rickettsiae important in medicine and veterinary medicine. These data are of fundamental importance to physicians, veterinarians, epidemiologists and others when, in their practices, they are confronted with epidemics of contagious diseases or outbreaks of foodborne illnesses. At such times prompt answers are often needed to limit the problem, and thus to protect the public's health. Since data needed for such a purpose are widely distributed in the internatio nal scientific literature, the occasional desperate literature search is likely to miss some of the information that is available. This book seeks to fill that void. It lies in the nature of a compilation such as this is that it can never be totally complete. The compilation requires continual up-dating to include new information, and some currently acceptable information may have to be corrected as new data become available. However, most of the information in this compilation will never be out-of-date. The authors are always thankful for suggestions from others. Collection of the data in this book resulted from, first, several decades of studying the literature, and, second, literature searches made by the Institut fUr Dokumentationswesen in Frankfurt a. M., the Biomedi zinische Datenbank of Hoechst A. G."

The intent of this publication is to bring together reviews and discussions from several disciplines, all treating the basidium and basidiocarp of the Basidiomy cotina (= basidiomycetes), a subdivision of the true or higher fungi. Because the workers who study the species of this group employ such a variety of techniques and publish in such diverse journals, we believe that bringing together these efforts in one publication will facilitate a synopsis of recent studies of several divergent disciplines. Correlation of such information may not only aid in the reevaluation of broad taxonomic and biological concepts but also provide a key to the specialists in the rethinking of the data available within the confines of the more restricted disciplines. We have attempted to cover the major areas of studies of species of the Basidiomycotina within the past decade or so with the exception of genetics and compatibility, which have recently been reviewed in several other works. A problem we have not been able to solve satisfactorily is the one of vocabulary. Each discipline tends to develop its own language as it becomes increasingly specialized, with time becoming unintelligible to the majority. We have tried to alleviate this problem of terms but can not claim to have been completely successful. We are indebted to a great many people, but especially to the contributors. They have been most patient and cooperative throughout."

Phenomena as diverse as tuberculin sensitivity, delayed sensitivity to soluble proteins other than tuberculin, contact allergy, homograft rejection, experimental autoallergies, and the response to many microorganisms, have been classified as members of the class of immune reactions known as delayed or cellular hypersensitivity. Similarities in time course, histology, and absence of detectable circulating immunoglobulins characterize these cell-mediated immune reactions in vivo. The state of delayed or cellular hypersensitivity can be transferred from one animal to another by means of sensitized living lymphoid cells (CHASE, 1945; LANDSTEINER and CHASE, 1942; MITCHISON, 1954). The responsible cell has been described by GOWANS (1965) as a small lymphocyte. Passive transfer has also been achieved in the human with extracts of sensitized cells (LAWRENCE, 1959). The in vivo characteristic of delayed hypersensitivity from which the class derives its name is the delayed skin reaction. When an antigen is injected intradermally into a previously immunized animal, the typical delayed reaction begins to appear after 4 hours, reaches a peak at 24 hours, and fades after 48 hours. It is grossly characterized by induration, erythyma, and occasionally necrosis. The histology of the delayed reaction has been studied by numerous investigators (COHEN et al. , 1967; GELL and HINDE, 1951; KOSUNEN, 1966; KOSUNEN et al. , 1963; MCCLUSKEY et al. , 1963; WAKSMAN, 1960; WAKSMAN, 1962). Initially dilatation of the capillaries with exudation of fluid and cells occurs.

During the past few decades we have witnessed an era of remarkable growth in the field of molecular biology. In 1950 very little was known of the chemical constitution of biological systems, the manner in which information was trans mitted from one organism to another, or the extent to which the chemical basis of life is unified. The picture today is dramatically different. We have an almost bewildering variety of information detailing many different aspects of life at the molecular level. These great advances have brought with them seme breath-taking insights into the molecular mechanisms used by nature for rep licating, distributing and modifying biological information. We have learned a great deal about the chemical and physical nature of the macromolecular nucleic acids and proteins, and the manner in which carbohydrates, lipids and smaller molecules work together to provide the molecular setting of living sys tems. It might be said that these few decades have replaced a near vacuum of information with a very large surplus. It is in the context of this flood of information that this series of monographs on molecular biology has been organized. The idea is to bring together in one place, between the covers of one book, a concise assessment of the state of the subject in a well-defined field. This will enable the reader to get a sense of historical perspective-what is known about the field today-and a description of the frontiers of research where our knowledge is increasing steadily."

The processes involved in herpesvirus replication, latency, and oncogenic transformation, have, in general, been rather poorly defined. A primary reason for this is the size and complexity of the herpesvirus genome. Undoubtedly, a better understanding of the functions of the viral genome in infected and transformed cells will be achieved through studies with temperature-sensitive (ts) mutants of herpesviruses since, theoretically, any essential gene function can be affected by mutants of this type. A. The Herpesviruses A consideration of the genetic analysis of members of the herpesvirus group necessitates a description, albeit brief, of the properties of the group and, most importantly, of their genetic material. The herpesviruses comprise a group of relatively large (100-150 nm), enveloped viruses. The envelope surrounds an icosahedral capsid enclosing a core which contains double stranded DNA (ROIZMAN, 1969). The group is thus defined on the basis of a common virion morphology. In addition to a common structure, members of the group share a number of biological properties such as a similar replicative cycle, the ability to cause latent and chronic infections, and the ability to induce antigenic modifications of infected cell membranes. Several herpes viruses have been associated recently with malignancies in man and animals (KLEIN, 1972). Herpesviruses are ubiquitous and have been described in over 30 different species (HUNT and MELENDEZ, 1969; WILDY, 1971; FARLEY et aI. , 1972; KAZAMA and SCHORNSTEIN, 1972; NAHMIAS et aI. , 1972; ROlZMAN et aI. , 1973). Their widespread occurrence in nature suggests a common ancestor.

1.1 Classification of Togaviruses The family, Togaviridae, is composed of the alphaviruses, the flaviviruses, rubella (a rubivirus), and the pestiviruses (Fenner, 1976). Of these four genera, two (the alpha- and flaviviruses) are transmitted by blood-sucking arthropods, specif ically mosquitoes and ticks. Among the togaviruses, extensive studies of defective interfering (DI) particles have so far been carried out only with Sindbis virus (SV) and Semliki Forest virus (SFV), both members of the alphavirus genus. Since these viruses are so similar, in most cases it will be assumed that what is true of one is also true of the other. 1.2 Definition of Defective Interfering (DI) Particles Defective interfering viral particles, as defined by Huang (1973), have the follow ing properties: (1) they are deletion mutants and therefore lack large amounts of the genetic material present in the standard virus; (2) they contain the same viral structural proteins as standard virus; (3) they are unable to replicate alone; however, they are replicated in cells co-infected with standard virions; and (4) at the same time as they require standard virus to replicate, they inhibit the replication of standard virus and hence are interfering."

This text is an overall view of nematology because I believe the science should be treated as a unified discipline. The differences in the biological habits of nematodes do not justify the separation of plant nematologists and animal nematologists, since the separation is not a reflection of any difIerences inherent to nematodes. Therefore, the book is arranged with a format that in the beginning chapters illustrates the similarities and se- quence of development of morphological characters among nematodes regardless of their biological habits. The later chapters illustrate the in- tegration of the evolutionary development of the parasitie habit from related free-living forms. Nematology is probably the last major discipline to establish its inde- pendence from the parent science of zoology. This natural evolvement of nematology has occurred because of the overwhelming accumulation of sophisticated information and research that reflects the unique relation- ships of nematodes to other forms of plant and animal life as weH as their relationships in other facets of the environment. N ematodes are inverte- brate animals that, like insects, are unusual in their great numbers and varieties, their smaH size (generally microscopic), their high degree of internal organization, and their virtually ubiquitous distribution. They oc- cupy almost every ecological niehe, often causing disease of humans, other animals, and plants. These activities often result in debility, death, or in the impairment and loss of food supply with consequent loss to producers and consumers.

Essential Microbiology and Hygiene for Food Professionals is an accessible and practical introduction, providing the basic science relating to microorganisms in food. Assuming no prior knowledge of microbiology, chapters take a fresh and modern approach in helping you to appreciate the importance of microbiology and hygiene in assuring food safety and quality, and demonstrate the application of key principles relating to the presence, detection and control of microorganisms in foods. *Accessible and practical introduction to food microbiology and food hygiene *Assumes no prior knowledge of microbiology *Highly illustrated including colour photographs, charts, diagrams and cartoons to aid learning and retention *Student-focused with quizzes and exercises throughout, summary boxes, vignettes and a glossary of technical terms *Weblinks to further information on the Internet Written in a user-friendly style, this book is an invaluable text for all those studying microbiology and hygiene on courses in the food professions, including food science, food technology, culinary arts, catering and hospitality, nutrition, dietetics, environmental health and public health.

This book provides a comprehensive and up-to-date collection of review articles focusing on RNA-mediated regulation in prokaryotes. The various modes of action include the direct interaction with proteins, direct sensing of metabolites or of physical parameters, and the interaction with RNAs to stimulate or prevent binding of ribosomes or to stimulate degradation. Written by leading experts in the field, the book covers small RNA functions, RNA thermometers, riboswitches, the diversity of small RNA-guided CRISPR-Cas defense systems and selected RNA chaperons in both prokaryotic domains, bacteria and archaea. Recent advances towards the computational identification of regulatory RNAs and their targets are included and particular attention is paid to small RNA in pathogenic bacteria. This volume is the only one exclusively covering regulatory RNAs in the prokaryotic domains to date, making it essential literature for anyone interested in RNA function and gene regulation and a valuable resource for teaching these concepts.

General pathologists see many biopsies from transplanted organs but few are in large enough centres so that this forms the bulk of their work. The book describes the changes which can be observed in transplantation in all of the major organ systems that are routinely transplanted and there are accounts of the pathology of infections and of the immunological difficulties that are faced by these patients. The volume will be a valuable guide for those who wish to braoden their knowledge in this field.

CURRENT TOPICS IN MEDICAL MYCOLOGY, VOLUME 4, like the pre- ceding three volumes in the series, is intended to summarize current research advances inmedical mycology. Topics ex- plored in this volume include skin kinetics of azole anti- fungal drugs; killer system interactions; fusarium-caused hyalohyphamycosis; molecular technique for epidemiologic ty- ping of Candida species; and the need for a mycoses-repor- ting system.

An intriguing class of biological periodicity consists of rhythms with about 24-hour periods occurring at every level of eukaryotic organization. Progress is being made in understanding these rhythms. The six chapters of this work include a brief introduction to circadian (24-hour) rhythms, a survey of circadian organization at the cellular level, and a description of the important microorganisms that have served as experimental models for biochemical analysis. Also considered are relations between cell division cycles and circadian oscillators, as well as some general and theoretical aspects. Where appropriate, parallels are drawn to neuronal oscillators. This volume will introduce and critically appraise modern chronobiology; its extensive illustrations and comprehensive up-to-date bibliography will make it an authoritative reference.

so easy it seemed Once found, which yet unfound most would have thought Impossible. (John Milton, 1608 -1674) There are essentially two types of books on a scientific subject: in the first one several authors contribute their specialized approaches to parts of the field in question, which then are edited and compiled to yield a comprehensive and authoritative account. In the second type of book a single author tries to pre sent a view from an individual standpoint which might lead to a more balanced and homogeneous source of information. Both kinds have their merits and de ficiencies. I decided to write this book as a monolithic piece of work for several rea sons. Of course, there was the challenge of coping with the many problems of such an undertaking due to the fact that this field has grown tremendously during the last decades. In addition, being heavily involved in linear oligopyr role chemistry for nearly two decades, it seemed worthwile to prepare a more unifying approach. The request of several colleagues from abroad to give an account in English also triggered this endeavor since most of the work of my group has been published in German."

Aquatic environments - marine and freshwater basins - are increasingly subject to anthropogenic stresses. Likewise, there is an increasing demand for better and more reliable methods for the monitoring and assessment of these large and important ecosystems and the interrelations between the physical and chemical features of water bodies. The use of radioisotopic techniques offers a wide range of methodological possibilities because all biologically active compounds contain long-living radioisotopes which make the analytical field and laboratory work possible without the precautions involved in direct radiation health hazards.