Current Topics in Vector Research is based on the premise that to un derstand the whole, one must first understand the component parts and how they interact. Here in Volume 4, as well as in future volumes, vector, pathogen, and host will be treated both individually and as integral parts of multifaceted transmission systems. It is our intention to present up-to date, coherent syntheses of the latest findings in vector research, suggest promising frontiers for future research, and call attention to possible prac tical applications of our present understandings of pathogen-vector-host interactions. To realize our goals, we invite world-renowned, veteran sci entists as well as neophytes to report on their individual areas of expertise. Where appropriate, authors are encouraged to draw conclusions and pro pose hypotheses that stimulate additional thinking and research or oth erwise further our understanding of vector transmission cycles and how such cycles might be interrupted. It is our hope that readers will agree that we are serving these objectives and creating a milieu for specialists and generalists in vector research to maintain rapport and understanding."

At this writing the decade of the 1980s is rapidly coming to a close, and it is an appropriate time to review the picornavirus field. During the past decade there has been a remarkable reemergence of interest in picornaviruses and a virtual explo- sion of experimentation. The renaissance of picorna viruses can be attributed to several developments near the beginning of the 1980s. In 1981 the nucleotide sequence of the first picornavirus genome, that of poliovirus, was determined, providing a genetic map that would be the basis for a number of experimental questions regarding gene function and expression (Kitamura et ai. , Nature 291: 547; Racaniello and Baltimore, Proc Natl Acad Sci USA 78: 4887). In the same year it was reported that a cloned eDNA copy of the poliovirus genome is infectious when transfected into cultured mammalian cells (Racaniello and Baltimore, Science 214: 916, 1981). This discovery, which enables construction of poliovirus mutants and recombinants, has since been used for the study of many picornaviruses. Furthermore, the availability of cloned copies of viral genomes permits manipulation of gene products apart from infected cells. Third, the use of hybridoma technology to generate anti- picornavirus neutralizing monoclonal antibodies permitted mapping of antigenic sites (for example, Evans et ai. , Nature 304: 459, 1983). Finally, at mid-decade the three-dimensional structures of poliovirus (Hogle et ai. , Science 229: 1358, 1985) and rhinovirus (Rossmann et ai. , Nature 317: 145, 1985) were solved.

Current Topics in Medical Mycology, which is a new annual series published by Springer-Verlag, is intended to summarize current topics in medical mycology for medical mycologists and other scientists who are work- ing in microbiology and immunology. Topics to be in- cluded in each year's volume will serve as contemporary reviews, summaries of current advancements and future directions, and mechanisms to enhance the interdiscipli- nary use of medically important fungi in the areas of pathogenesis, epidemiology, mycotoxins, taxonomy, and other areas where basic, applied, and clinical science are used. Michael R. McGinnis Contents ix Contributors 1 Pathology of the Mycoses in Patients with the Acquired Immunodeficiency Syndrome (AIDS) FRANCIS W. CHANDLER 1 Composition and Structure of Yeast Cell 2 Walls 24 GRAHAM H. FLEET 3 Animal Models for Candidiasis M. NEAL GUENTZEL, GARRY T. COLE, and 57 LEODOCIA M. POPE 4 Dermatophyte Antigens and Cell-Mediated Immunity in Dermatophytosis 117 TAAVIKAAMAN 5 Natural Cell-Mediated Resistance Against Cryptococcus neoformans: A Possible Role for Natural Killer (NK) Cells J UNEANN W. M URPHY 135 6 Biotyping of Medically Important Fungi FRANK C. ODDS 155 7 Characterization of Protein and Mannan Polysaccharide Antigens of Yeasts, Moulds, and Actinomycetes ERROL REISS, MILTON HUPPERT, and ROBERT CHERNIAK 172 Contents viii The Changing Epidemiology and Emerging 8 Patterns of Dermatophyte Species 208 JOHN WILLARD RIPPON 9 Paracoccidioides brasiliensis: Cell Wall Glucans, Pathogenicity, and Dimorphism GIOCONDA SAN-BLAS 235 10 The Role of Zinc in Candida Dimorphism 258 DAvID R. SOLL 11 Killer Yeasts REED B.

Mucosal immunity encompasses a broad field of research that includes areas of epithelial cell and molecular biology, molecular and cellular immunology, microbiology, virology, and vaccinology. This volume presents up to date and concise discussions of concepts as well as recent advances. It provides an overview of the components of the mucosal immune system, and the basic science relevant to mucosal vaccination. The authors assess current research in critical areas including: Organization of mucosal lymphoid tissue; antigen sampling and presentation in mucosal tissues; mucosalimmune responses and tolerance; immune effectors at mucosal sites; microbial-host interactions at mucosal sites; mucosal vaccines and adjuvants. This multi-disciplinary effort will be a valuable resource for researchers, clinicians and students who need a clear understanding of concepts and a guide to the wide-ranging literature in this very active research area.

This volume contains papers presented at the international conference on "Transgenic Mice and Mutants in MHC Research", held in Bar Harbor, Maine, in June, 1989. The meeting brought together eighty researchers working in the field. While mouse H-2 mutants have been known for many years their studies continue to contribute a great deal to our understanding of structure/function relationships and evolution of MHC molecules. Recently a new direction of research has emerged on regulation, expression and function of MHC genes using transgenic animals carrying exogenous MHC genes from the same or other species or engineered MHC genes. With the introduction of transgenic mice more specific questions about the various functions of MHC genes can be answered as, for example, the role of soluble and membrane-bound MHC molecules in self tolerance and elimination of specific T cell clones, recognition of human MHC antigens by the mouse immune system, the role of individual human MHC genes in disease susceptibility. New approaches for evaluation of the role of MHC linked and unlinked genes in susceptibility of mice to malignant tumors and their metastases have been also reported. Our purpose has been to provide a forum for discussion of these new developments. Many questions remain to be answered but the necessary tools have become available. We thank the contributors and hope that the readers will benefit from this Pro ceedings. We wish to acknowledge the financial sponsorship for the meeting by The Pew Charitable Trust and Howard Hughes Medical Institute.

The newest volume in the Current Topics in Microbiology and Immunology series edited by Dr. Vogt and dealing with oncogenes and retroviruses contains four review articles by international authorities in the field. These articles presenting the latest research results continue the tradition of excellence for which the series is so well known.

Parasitic zoonoses, the parasitic diseases transmitted between humans and other vertebrate animals, are widespread. The increasing pace of internationalization changes in diet and easy movement from one part of the world to another has caused parasitic zoonoses to be more prevalent. Consequently, these diseases have become the focus of recent research by parasitologists and pathologists whose work is presented in this book. Included in addition to the pathology of parasitic zoonoses and recent trends in research of imported parasites are the classification of phenotypes of anisakid nematodes, the immunohistopathological diagnostic method, and molecular technology to detect and diagnose parasites. Also included are papers on parasitology and international health and the pathology of cerebral malaria. With 38 color illustrations, this book is an invaluable resource for parasitologists, pathologists, and clinicians.

Michael Potter, Fritz Melchers, Martin Weigert The second workshop on Mechanisms of B Cell Neoplasia was held in Bethesda, Maryland in Wilson Hall at the National Institutes of Health on March 5, 6, and 7, 1984. It followed a workshop on the same topic that was held at the Basel Institute for Immunology, March 15-17, 1983. That first meeting attempted to bring together cell biologists, experimental pathologists and molecular geneti- cists interested in B cells, to discuss pathogenetic processes in the development and maintenance of the neoplastic state. The impetus for this discussion emanated from two important developments: first, the discovery of the viral promoter insertion mechanism for acti- vating the myc oncogene in bursal lymphomatosis by Hayward, Neil, and Astrin;-second, the findings that the non-random chromosomal trans locations involving the immunoglobulin gene chromosomes occur- red in very high frequencies in murine plasmacytomas and human Burkitt's lymphomas. During the planning stages of that meeting Shen-Ong et al. discovered that non-random translocations activated the myc oncogene. Promoter insertions and non-random trans locations were-rwo mechanisms that caused transcription of the myc oncogene messages in three different kinds of well defined experimental and clinical B cell tumors. Unregulated myc gene transcription provided the first evidence of a specific bioChemical lesion in B cell neo- plasia.

Tuberculosis has plagued mankind since prehistoric times and is still an important source of morbidity and mortality, with particularly devastating effects in developing and tropical countries. Tuberculosis results from an infection with Myeo baeterium tubereu/osis, and the World Health Organization estimates that perhaps as much as one-third of the world's population or approximately 1. 9 billion persons are or have been infected with M. tubereu/osis. Each year, there are 8-10 million new cases of tuberculosis and about 3 million deaths due to it. Indeed, tuberculosis is the leading cause of death in adults due to a single infectious agent and accounts for ap proximately 26% of all preventable adult deaths in the world. In addition, tuberculosis is an enormous social and economic problem because approximately 95% of new cases occur in developing countries and because about 80% of tuberculosis cases affect persons of child-bearing age and du ring their most economically productive years (ages 15-59). Tuberculosis has also re-emerged as an important public health problem in many developed countries. For example, between 1985 and 1992, the number of tuberculosis cases reported to the United States Centers for Disease Control and Prevention increased by more than 20%. Similarly, Austria experienced a 5% increase in tuberculosis cases from 1987 to 1991, Ireland a 9% increase from 1988 to 1991, Denmark a 20% increase from 1987 to 1992, and Italy a 27% increase from 1988 to 1992."

Research in diabetes has accelerated in two areas, both of which are being reviewed in CTMI. The first is the use of a variety of animal models; the second is basic research in human investigation, islet cell antigens, and mapping of genes as sociated with susceptibility to disease. Dr. Thomas Dyrberg accepted editorial responsibility for this volume, which covers the first area. A second book, to be published later in the year, is edited by Drs. Brekkeskov and Hansen (CTMI 164, see page VI for contents). Although the contributors to both volumes represent the international scientific community, the editors are from the Hagedorn Research Laboratory in Denmark. Work at this institute and the Steno Memorial Hospital has been dedicated to research in diabetes for decades, and the insti tutions were appointed WHO Collaborating Centres for Re search and Training on the Pathogenesis of Diabetes Mellitus in 1983. It is worth noting that while addressing the hypothesis of the role of class II major histocompatibility glycoproteins in autoimmune diabetes (insulin-dependent diabetes, IDDM) a number of investigators established animal models in which class II molecules were expressed under the control of the rat insulin promoter. While generating interesting information on 100M, the finding of immunologic tolerance in such transgenic mice has attracted the attention of several basic immunologic laboratories for quite different reasons. Thus, we are reminded again of the Pasteur dictum that "chance favors the prepared mind. " Michael B. A. Oldstone, M. D."

The ADG held its first International Symposium at Churchill College, Cambridge, in July 1979. The second symposium was also held at Churchill College on 30-31 July, 1981, and this, the third, took place at the same college on 30-31 July, . 1983. The meeting was structured in a format which we hoped would appeal to the full range of our membership. The philosophy of the ADG is that medical microbiologists, veterinarians, toxicologists and dental bacteriologists have much to learn from each other and can best be achieved by bringing these various disciplines together frequently and in informal surroundings. Again the symposium was very generously sponsored by May and Baker Limited who met all costs of the meeting and entertained us splendidly. David Jackson and Donald Bedford were re sponsible for coordinating with the ADG on behalf of May and Baker and, as usual, gave us their full cooperation. This book contains the full-length papers, followed by the posters presented at the meeting. This book also serves as a vehicle for the abstracts of the first meeting of the Society for Intestinal Microbial Ecology and Disease, SIMED, held in Boston, Massachusetts. An introduction to this new society by its President, Sydney M. Finegold, M.D., precedes the abstracts. M.J. Hill VI CONTENTS Preface v List of contributors VIII Introduction to the Anaerobe Discussion Group M.J. Hill XI A guinea-pig model demonstrating synergy between Escherichia coli and Bacteroides fragilis in infected surgical wounds."

Gene cloning for the production of recombinant DNA is usually performed with E. coli. There is, however, no doubt that gene cloning in organisms other than E. coli will assume a much more important role in the future: efficient cloning systems are needed for the analysis of gene expression and its regulation in eukaryotic cells, for the elucidation ofthe genetic mechanisms of transform a- tion, and for the study of the genetic rearrangement during dif- ferentiation and embryogenesis. Furthermore, optimal cloning systems will be required for practical applications in the near future: for the optimal production of antibiotics, amino acids, vitamins, enzymes etc. , for the expression of gene products under favorable energetic conditions for mass production, for the ex- pression of glycolysated animal proteins, for the genetic manipu- 'lation of plants -and in the more distant future, for gene therapy inman. The editors have therefore invited leading scientists to sum- marize the present status and the future applicability of gene cloning systems in their fields of research. To ensure a complete coverage of a genetic system, the editors have generally asked two authors to cover one system. This volume is a frrst and unique account of our knowledge of cloning systems employing organisms other than E. coli such as B. subtilis, pseudomonas, neurospora, saccharomyces and streptomyces, as well as of vectors and selection procedures for animal and plant systems including the liposome technique. October 1981 P. R.

The fact that none of the known DNA polymerases is able to initiate DNA chains but only to elongate from a free 3' -OH group raises the problem of how replication is initiated, both at the replication origin and on Okazaki frag ments. It was first shown by A. KORNBERG et al. that a general mechanism to initiate replication is through the formation of an RNA primer catalyzed by RNA polymerases or by a new class of enzymes, the primases (KORNBERG 1980). This mechanism, which can be used in the case of circular DNA molecules or linear DNAs that circularize or form concatemers, cannot be used at the ends of linear DNAs since the RNA primer is removed from the DNA chain, and there is no way of filling the gap resulting at the 5' -ends of the newly synthesized DNA chain. In some cases linear DNA molecules contain a palin dromic nucleotide sequence at the 3' -end that allows the formation of a hairpin structure which provides the needed free 3'-OH group for elongation. This mechanism, first proposed by CAVALIER-SMITH (1974) for eukaryotic DNA repli cation, was shown to take place in several systems (KORNBERG 1980, 1982). Another mechanism to initiate replication consists in the specific nicking of one of the strands of a circular double-stranded DNA, producing a 3'-OH group available for elongation (KORNBERG 1980)."

If tumor viruses did not exist in nature they might have been created by scientists interested in basic mechanisms of develop- ment, differentiation, and tumorigenesis. In contemporary euka- ryotic cell biology tumor viruses playa similar role to that which bacteriophages once had for the molecular biology of prokary- otes. Tumor viruses provide extremely useful probes for the above cellular processes since their life cycle is genetically pro- grammed and can be followed at DNA, RNA, and protein levels. The experimental systems reviewed in this volume utilize a wide variety of viruses. A comprehensive introduction to this field has recently been published in the volumes of Molecular Biology o/Tumor Viruses: DNA Tumor Viruses, 2nd edition, edited by J. Tooze; and Molecular Biology o/Thmor Viruses: RNA Tumor Viruses, 2nd edition, edited by R. Weiss, N. Teich, H. Varmus, and J. Coffm, by Cold Spring Harbor Laboratories in 1980 and 1982. Polyoma and SV40 viruses (see the chapter by A. Levine) and adenoviruses (see the chapter by W. Doerfler) are double- stranded DNA-containing viruses. Polyoma and SV40 are struc- turally related viruses which contain a genome of approximately 5 kilo basepairs, while the DNA of adenovirus is about 7 times more complex. These DNA tumor viruses are understood at a genetic and molecular level which is comparable to our know- ledge of A and T4 bacteriophages. Retroviruses, the subject of the remaining four chapters, con- tain a single-stranded RNA genome of 5-8 kilobases.

In the past ten years there has been enormous progress in the development of eukaryotic viral vectors. In general, these vectors have been developed for one of three reasons: to achieve high levels of expression of a particular gene product (poxvirus, baculovirus, and adenovirus), to clone eukaryotic genes in combination with functional assays (Epstein-Barr virus), of for use as delivery vehicles for the stable introduction of foreign genes into mammalian cells (retroviruses, Epstein-Barr virus, and adeno-associated virus). Each vector has its strengths and weaknesses that are rooted in the sometimes bewildering stra tegies that the parent viruses use for propagation. No one of these vectors is appropriate for all of the problems that a mole cular biology laboratory is likely to encounter, and few of us are knowledgeable in the molecular virology of all of these viruses. This volume represents an attempt by the authors to assem ble a review of these vectors in one place and in a form useful to laboratories that do not necessarily have experience with eukaryotic viruses. Clearly, any virus can be modified to serve as a vector for some purposes, and it was not possible to include a description of all of these. In addition, one eukaryotic vector, SV40 (the first one developed), has been reviewed so widely that we saw no reason to include it here."

Genetic / DNA immunization represents a novel approach to vaccine and immune therapeutic development. The direct injec tion of nucleic acid expression cassettes into a living host results in a limited number of its cells becoming factories for production of the introduced gene products. This host-inappropriate gene expression has important immunological consequences, resulting in the specific immune activation of the host against the gene delivered antigen. The recent demonstration by a number of laboratories that the induced immune responses are functional in experimental models against both specific infectious diseases and cancers is likely to have dramatic consequences for the develop ment of a new generation of experimental vaccines and immune therapies. This technology has the potential to enable the pro duction of vaccines and immune-based therapies that are not only effective immunologically but are accessible to the entire world (rather than just to the most developed nations). Vaccine Development Vaccination against pathogenic microorganisms represents one of the most important advances in the history of medicine. Vaccines, including those against polio, measles, mumps, rubella, hepatitis A, hepatitis B, pertussis and other diseases, have dramatically improved and protected more human lives than any other avenue of modern medicine. The vaccine against smallpox, for example, has been so successful that it is now widely believed that this malicious killer, responsible for more deaths in the twentieth century than World Wars I and II combined, has been removed from the face of the earth.

The great majority of bacterial infections are initiated by the adhesion of pathogenic bacteria to cells and mucosal surfaces of the host. The sequela of adhesion may range from the action of toxins outside target cells to their penetration into or through tissue. Besides the consequences of bacterial adhesion related in infection, the result may be colonization of mucosal surfaces with normally harmless bacteria, which in stress situations may become virulent, a phenomenon known as nosocomial infections. With very few exceptions, adhesion is carbohydrate speci fic. It is mediated by bacterial recognition proteins that are, according to the phenomenon studied, termed adhesins or hem agglutinins; the term "lectin" is sometimes also used. The chemical nature of the ad he sins and their organization on the bacterial surface have been studied intensively in many laboratories. The application of genetic and biochemical techniques has led to substantial progress in the molecular characterization of adhesins in recent years. We now know that adhesins may occur as structural subunits of fimbriae and that they may form fimbriae which can be considered as mono- or multifunctional linear adhesin polymers. Other adhesins do not form recognizable structures and are tenta tively called nonfimbrial. Adhesins may even be components of bacterial cell walls. Adhesin-receptor specificities have been unravelled. The study of the distribution of receptors in tissue has created implications about the possible susceptibility to infections.

When it comes to bacterial disease, we are living in a state of false security. Antibiotics have indeed brought unprecedented health benefits, protection from and cure of bacterial diseases during the past 50 years. But there are ominous signs that the fortress and the defenses built on antibiotics are crumbling. They are crum bling because we wittingly or unwittingly created selective con ditions for the emergence of superior pathogens that can no longer be controlled by antibiotics. There are numerous warnings. After a long period of eclipse tuberculosis has now emerged as a serious threat unchecked by antibiotic treatment. Recent years have seen reports of cholera epidemics, of anthrax infections, of serious problems with Salmonella and even with E. coli, just to name a few. Mankind is in a race with microbial invaders. The challenge is to anticipate and respond to developments that affect the precarious balance between man and microbe. This will re quire new knowledge and it will take time for an effective appli cation of that knowledge."

A century ago the Italian pathologist Bizzozero described the relationships between spiral bacteria and the mammalian gastro intestinal tract. Since 1982, when Helicobacter pylori was discovered, gastroduodenal disease have been completely revised as a con sequence of the results of basic and clinical research in this field. Progress in understanding the pathogenesis of this bacterium has been made by studying H. pylori infection in animal models. More specific diagnostic tools have been developed using new molecular biology techniques. Future trends are directed towards preparing a specific H. pylori vaccine. A new classification for gastritis, the Sydney System, including H. pylori gastritis, was proposed in 1990. As concerns the clinical approach to peptic ulcer disease in the 1990's, the majority of authors agree on the importance of H. pylori eradication. Moreover, recent clinical studies suggest that H. pylori infection can be associated with other gastroduodenal diseases, such as non ulcer dyspepsia and gastric cancer. Multicenter trials to standardize serological methods and evaluate the efficacy of new antimicrobial therapy schedules are planned throughout different European countries. The fourth Workshop of the European Helicobacter Pylori Study Group was held in Bologna, Italy, in November 1991. Two years before Bologna University celebrated its ninth centennial, giving evidence of being the oldest University in the modern world. Thus the H. pylori story that has continued for more than a century has been discussed once again at the University with the oldest tradition in the world."

Human gene therapy holds great promise for the cure of many genetic diseases. In order to achieve such a cure there are two requirements. First, the affected gene must be cloned, its se quence determined and its regulation adequately characterized. Second, a suitable vector for the delivery of a good copy of the affected gene must be available. For a vector to be of use several attributes are highly desirable: these include ability to carry the intact gene (although this may be either the genomic or the cDNA form) in a stable form, ability to introduce the gene into the desired cell type, ability to express the introduced gene in an appropriately regulated manner for an extended period of time, and a lack of toxicity for the recipient. Also of concern is the frequency of cell transformation and, in some cases, the ability to introduce the gene into nondividing stem cells. Sev eral animal viruses have been tested as potential vectors, but none has proven to have all the desired properties described above. For example, retroviruses are difficult to propagate in sufficient titers, do not integrate into nondividing cells, and are of concern because of their oncogenic properties in some hosts and because they integrate at many sites in the genome and, thus, are potentially insertional mutagens. Additionally, genes introduced by retroviral vectors are frequently expressed for relatively short periods of time. A second virus used as a vector in model systems has been adenovirus (Ad)."

Many of the fundamental concepts of animal virology originated from the study of the variola-cowpox-vaccinia virus system with vaccinia virus serving as the type species (Fen- nerand Burnet 1957; Burnet 1959; Fenner 1976a, b). The importance of the Poxviridae(Fen- ner 1979) for the study of viruses as biologic entities and in defIning the events which occur in virus-infected cells are exemplifIed by investigations which: (a) described the epidemiology of a virus disease in an animal population (Fenner1949, 1959b); (b) em- ployed electron microscopy to study virion structure (Peters 1956, Nagington and Home 1962, Dales and Siminovitch 1961) and to derme the morphologic stages of virion develop- ment in infected cells (Morgan et al. 1954, Dales 1963); (c) dermed and elaborated on the mechanism of nongenetic reactivation for an animal virus (Joklik et al. 1960a, Fenner and Woodroofe 1960, Hanafusa 1960); (d) described the intracellular uncoating of a viral genome (Joklik 1964a, b); (e) studied the antigenic structure and complexity of poxvirions (Loh and Riggs 1961, Woodroofe and Fenner 1962, Appleyard et al. 1964, Appleyard and Westwood 1964); (1) described the use of chemotherapy to treat viral infec- tions (Bauer et al. 1963); (g) fIrst demonstrated the presence of virion-coded enzymes encapsulated within virions (Kates and McAuslan 1967, Munyon et al. 1967); and (h) established the H -2 restriction of cytotoxic T-cell killing of virus-infected cells in the murine system (Doherty et al. 1976).

Die Naturwissenschaften; Edward Arnold Co.; Research in Veterinary Science; Ltd.; Farm Mechanization and Buildings; Springer Verlag; The Ciba Foundation Ltd.; Journal of Agricultural Science; Journal of The Institute of Biology; The Lancet; The Reproduction and Fertility; Lea and Febiger; Physiological Society (G. B.); The Royal Masson et Cie, Paris; MacMillan Publishing Society; University of Chicago Press; Uni- Co., Inc.; National Academy of Science, versity of Rhodesia; Verhandlungen der U.S.; National Research Council of Canada; Deutschen Gesellschaft fur KreislautJorsch- Nature, London; North Holland Publishing ung; Waverly Press; and W. B. Saunders. Co.; Oxford University Press; Pergamon Press; Physiology and Behavior; Poultry D. L. INGRAM Science Association; Reinhold Publishing L. E. MOUNT Contents Preface Chapter 1 The Thermal Eml'ironment 1 Hot, Thermally Neutral, and Cold Environments 1 Development of Climatic Physiology 3 Physical Principles Chapter 2 Heat Exchange between Animal and Environment 5 Metabolic Heat and Its Dissipation 5 Body Temperature 6 Poikilotherm and Homeotherm 7 Heat Flow 8 Sensible Heat Transfer 9 Evaporative Heat Transfer 16 Calorimetry 21 Chapter 3 Metabolic Rate, Thermal Insolation, and the Assessment of Environment 24 Metabolic Rate and Heat Loss at High Temperatures 24 Thermal Conductance and Insulation 27 Evaporative Heat Loss 31 The Assessment of Thermal Environment 34 Responses of Different Species to High Temperatures 37 Physiological Mechanisms Chapter 4 Evaporative Heat Loss 39 Evaporative Loss from the Respiratory Tract 39 ix x Contents Conservation of Water Loss from the Respiratory 40 Tract in a Hot Dry Climate

The present volume contains 17 lectures of the 41 st Mosbach Colloquium of the Gesellschaft fiir Biologische Chemie, held from April 5-7, 1990 on the topic "The Molecular Basis of Bacterial Metabolism". From the beginning it was not the intention of the organizers to present a comprehensive account, but rather to select new, exciting progress on sometimes exotic reactions of specifically bacterial, mainly anaerobic metabolism. Members of our society had contributed to this progress to an extent that greatly stimulated the scientific exchange with international colleagues during the days in Mosbach. The editors hope that this stimulation will be conveyed to the readers of the articles, which reach from the biochemistry of methanogenesis, via anaerobic radical reactions, metal biochemistry in hydrogen and nitrogen metabolism, conversions of light - and redox energy, to the regulation of metabolic adaptation, and the attempts to bioengineer novel pathways for the degradation of xenobiotica. We believe that the book represents a highly progressive field of over lapping disciplines, comprising microbiology and molecular genetics, chemistry of biomimetic interest, and biophysics, and that it gives insight into the impact modern technologies have on microbiological research today. The colloquium was generously supported by the Deutsche Forschungsgemeinschaft, the Paul-Martini-Stiftung, and the Fonds fiir Biologische Chemie. A. Trebst, G. Schafer, and D. Oesterhelt were a great help in preparing the program and we wish to thank them for their advice.

The last decade has seen an explosion in our understanding of how bacterial pathogens trick, cajole, usurp and parasitize their various hosts. This renaissance is due to the convergence of molecular and cellular techniques with the power of microbial genetics. The purpose of this volume is to introduce recent advances in understanding selected systems chosen from both plant and animal hosts of bacterial pathogens. This somewhat nonobvious choice of topics was spurred by the recent findings, detailed by several conributors to this volume, of common systems used to secrete virulence factors from pathogens of both plants and animals. These serendipitous findings underscored the importance of basic research approaches to parallel problems in biology. More importantly, they brought together investigators who may not have otherwise become conversant with each other's experimental systems. I, for one, find the kinds of synergism reflected in a volume of this sort to be one of the most pleasant aspects of science and hope that the reader, whether a newcomer to the field or an expert, can find a new slant to old problems in the reviews contained h, E: lre. It was, however, necessary to limit volume length, and this has forced the exclusion of a number of fascinating bacterial pathosystems.