Between Pathogenicity And Commensalism

This comprehensive, interdisciplinary book covers different aspects of relevant human pathogens and commensals. The ongoing development of (meta-)genomic, transcriptomic, proteomic and bioinformatic analyses of pathogenic and commensal microorganisms and their host interaction provides a comprehensive introduction to the microbiological analysis of host-microbe interplay and its consequences for infection or commensalism.

This comprehensive, interdisciplinary book covers different aspects of relevant human pathogens and commensals. The ongoing development of (meta-)genomic, transcriptomic, proteomic and bioinformatic analyses of pathogenic and commensal microorganisms and their host interaction provides a comprehensive introduction to the microbiological analysis of host-microbe interplay and its consequences for infection or commensalism.

One of the most profound paradigms that have transformed our understanding about life over the last decades was the acknowledgement that microorganisms play a central role in shaping the past and present environments on Earth and the nature of all life forms. Each organism is the product of its history and all extant life traces back to common ancestors, which were microorganisms. Nowadays, microorganisms represent the vast majority of biodiversity on Earth and have survived nearly 4 billion years of evolutionary change. Microbial evolution occurred and continues to take place in a great variety of environmental conditions. However, we still know little about the processes of evolution as applied to microorganisms and microbial populations. In addition, the molecular mechanisms by which microorganisms communicate/interact with each other and with multicellular organisms remains poorly understood. Such patterns of microbe-host interaction are essential to understand the evolution of microbial symbiosis and pathogenesis.Recent advances in DNA sequencing, high-throughput technologies, and genetic manipulation systems have enabled studies that directly characterize the molecular and genomic bases of evolution, producing data that are making us change our view of the microbial world. The notion that mutations in the coding regions of genomes are, in combination with selective forces, the main contributors to biodiversity needs to be re-examined as evidence accumulates, indicating that many non-coding regions that contain regulatory signals show a high rate of variation even among closely related organisms. Comparative analyses of an increasing number of closely related microbial genomes have yielded exciting insight into the sources of microbial genome variability with respect to gene content, gene order and evolution of genes with unknown functions. Furthermore, laboratory studies (i.e. experimental microbial evolution) are providing fundamental biological insight through direct observation of the evolution process. They not only enable testing evolutionary theory and principles, but also have applications to metabolic engineering and human health. Overall, these studies ranging from viruses to Bacteria to microbial Eukaryotes are illuminating the mechanisms of evolution at a resolution that Darwin, Delbruck and Dobzhansky could barely have imagined. Consequently, it is timely to review and highlight the progress so far as well as discuss what remains unknown and requires future research. This book explores the current state of knowledge on the molecular mechanisms of microbial evolution with a collection of papers written by authors who are leading experts in the field.

Infectious diseases have existed longer than us, as long as us, or are relatively newer than us. It may be the case that a disease has existed for many, many years but has only recently begun affecting humans. At the turn of the century the number of deaths caused by infections in the United States had been falling steadily but since the '80s has seen an increase. In the past 30 years alone 37 new pathogens have been identified as human disease threats and 12% of known human pathogens have been classified as either emerging or remerging. Whatever the story, there is currently a "war" on infectious diseases. This war is simply the systematic search for the microbial "cause" of each disease, followed by the development of antimicrobial therapies. The "war" on infectious diseases, however, must be revisited in order to develop a more realistic and detailed picture of the dynamic interactions among and between host organisms and their diverse populations of microbes. Only a fraction of these microbes are pathogens. Thus, in order to explore the crafting of a new metaphor for host-microbe relationships, and to consider how such a new perspective might inform and prioritize biomedical research, the Forum on Microbial Threats of the Institute of Medicine (IOM) convened the workshop, Ending the War Metaphor: The Changing Agenda for Unraveling the Host-Microbe Relationship on March 16-17, 2005. Workshop participants examined knowledge and approaches to learning about the bacterial inhabitants of the human gut, the best known host-microbe system, as well as findings from studies of microbial communities associated with other mammals, fish, plants, soil, and insects. The perspective adopted by this workshop is one that recognizes the breadth and diversity of host-microbe relationships beyond those relative few that result in overt disease. Included in this summary are the reports and papers of individuals participating in the Forum as well as the views of the editors.

This volume focuses on those instances when benign and even beneficial relationships between microbes and their hosts opportunistically change and become detrimental toward the host. It examines the triggering events which can factor into these changes, such as reduction in the host’s capacity for mounting an effective defensive response due to nutritional deprivation, coinfections and seemingly subtle environmental influences like the amounts of sunlight, temperature, and either water or air quality. The effects of environmental changes can be compounded when they necessitate a physical relocation of species, in turn changing the probability of encounter between microbe and host. The change also can result when pathogens, including virus species, either have modified the opportunist or attacked the host’s protective natural microflora. The authors discuss these opportunistic interactions and assess their outcomes in both aquatic as well as terrestrial ecosystems, highlighting the impact on plant, invertebrate and vertebrate hosts.

Plants and animals have evolved ever since their appearance in a largely microbial world. Their own cells are less numerous than the microorganisms that they host and with whom they interact closely. The study of these interactions, termed microbial symbioses, has benefited from the development of new conceptual and technical tools. We are gaining an increasing understanding of the functioning, evolution and central importance of symbiosis in the biosphere. Since the origin of eukaryotic cells, microscopic organisms of our planet have integrated our very existence into their ways of life. The interaction between host and symbiont brings into question the notion of the individual and the traditional representation of the evolution of species, and the manipulation of symbioses facilitates fascinating new perspectives in biotechnology and health. Recent discoveries show that association is one of the main properties of organisms, making a more integrated view of biology necessary. Microbial Symbioses provides a deliberately “symbiocentric outlook, to exhibit how the exploration of microbial symbioses enriches our understanding of life, and the potential future for this discipline. Offers a concise summary of the most recent discoveries in the field Shows how symbiosis is acquiring a central role in the biology of the 21st century by transforming our understanding of living things Presents scientific issues, but also societal and economic related issues (biodiversity, biotechnology) through examples from all branches of the tree of life

Polymicrobial diseases, those involving more than one etiologic agent, are more common than is generally realized and include respiratory diseases, gastroenteritis, conjunctivitis, keratitis, hepatitis, periodontal diseases, multiple sclerosis, genital infections, intra -- abdominal infections, and pertussis.

What constitutes animal welfare? With animals being used for companionship, service, research, food, fiber, and by-products, animal welfare is a topic of great interest and importance to society. As the world's population continues to increase, a major challenge for society is the maintenance of a strong and viable food system, which is linked to t