First published in 1987, The Effects of Low Temperatures on Biological Systems takes a broad view of the interactions of low temperatures with biological conditions. The topics covered range from molecular effects to whole organism behaviour and include practical applications in medicine, agriculture and the food industry. This integrated, multi-disciplinary approach to cryobiology presents a wide spectrum of topics linked by theory and interpretation, provides a unified concept of the subject and may stimulate fruitful pathways for further thought and research. The expert contributors to this book were chosen by the editors to represent an integrated science of cryobiology.
First published in 1987, The Effects of Low Temperatures on Biological Systems takes a broad view of the interactions of low temperatures with biological conditions. The topics covered range from molecular effects to whole organism behaviour and include practical applications in medicine, agriculture and the food industry. This integrated, multi-disciplinary approach to cryobiology presents a wide spectrum of topics linked by theory and interpretation, provides a unified concept of the subject and may stimulate fruitful pathways for further thought and research. The expert contributors to this book were chosen by the editors to represent an integrated science of cryobiology.
The purpose of the symposium on which this book is based was to present, by means of a series of papers dealing with representative problems, a cross-section of contemporary research on temperature relations of biological processes at various levels of complexity, extending from the purely molecular, up through cells, tissues, organs, to whole organisms. In the aspect of the same subject, papers dealing primarily with the action of hydrostatic pressure.
To humans, cold has a distinctly positive quality. 'Frostbite', 'a nip in the air', 'biting cold', all express the concept of cold as an entity which attacks the body, numbing and damaging it in the process. Probably the richness of descriptive English in this area stems from the early experiences of a group of essentially tropical apes, making their living on a cold and windswept island group half way between the Equator and the Arctic. During a scientific education we soon learn that there is no such thing as cold, only an absence of heat. Cold does not invade us; heat simply deserts. Later still we come to appreciate that temperature is a reflection of kinetic energy, and that the quantity of kinetic energy in a system is determined by the speed of molecular movement. Despite this realization, it is difficult to abandon the sensible prejudices of palaeolithic Homo sapiens shivering in his huts and caves. For example; appreciating that a polar bear is probably as comfortable when swimming from ice floe to ice floe as we are when swimming in the summer Mediterranean is not easy; understanding the thermal sensa tions of a 'cold-blooded' earthworm virtually impossible. We must always be wary of an anthropocentric attitude when considering the effects of cold on other species.
Notwithstanding widespread studies and even several biological journals devoted to temperature, it is difficult to perceive a field of thermobiology as such. Interest in the effects of temperature of biological systems is fragmented into specific thermal ranges and often connected with particular applications: subzero cryobiology and preservation of cells and tissues or survival of poikilotherms, para-zero cryobiology and preservation of whole organs and survival of whole animals, intermediate ranges and physiological adaption and regulation, high temperatures and use of heat for killing cancer cells, very high temperatures and limits of biological structure. Yet it has not always been so, and there are good reasons why it need not remain so. General and comparative physiologists such as W.J. Crozier, H. Precht, J. Belehradek, F. Johnson, C.L. Prosser, and others have sought throughout this century to lay foundations for unified approaches to temperature in biological systems.Recent findings also serve to suggest principles and processes that span the range of temperatures of biological interest. Microviscosity of membranes is an issue originally of interest to low temperature biologists but with relevance to limiting high temperatures; conversely for protein structure. Certain "heat shock proteins" now appear to be responses to generalized stress, including low temperature.Inevitably, the chapters of this book reflect the "zonal" character of thermobiology: two chapters (by Storey and Raymond) deal with protection against subfreezing temperatures; three (Hazel, membrane structure, Dietrich, microtubular structure, and Kruuv, cell growth) deal with the effects of and modulation to cool-to-moderate superfreezing temperatures, one (Willis) with modulation (of membrane ion transport) to moderate-to-high temperatures and two (Li, heat shock proteins and Lepock, proteins in general) with stressfully high temperatures. Explicit in each of these chapters, however, are principles and issues that transcend the parochialism of the temperature range under consideration.
Low temperature is a major environmental constraint impacting the geographic distribution and seasonal activity patterns of insects. Written for academic researchers in environmental physiology and entomology, this book explores the physiological and molecular mechanisms that enable insects to cope with a cold environment and places these findings into an evolutionary and ecological context. An introductory chapter provides a primer on insect cold tolerance and subsequent chapters in the first section discuss the organismal, cellular and molecular responses that allow insects to survive in the cold despite their, at best, limited ability to regulate their own body temperature. The second section, highlighting the evolutionary and macrophysiological responses to low temperature, is especially relevant for understanding the impact of global climate change on insect systems. A final section translates the knowledge gained from the rest of the book into practical applications including cryopreservation and the augmentation of pest management strategies.
It is now well recognised that many environments considered by man to be extreme are colonised by micro-organisms which are specifically adapted to these ecological niches. These organisms not only survive but actively grow under such conditions. A diverse range of bacteria, cyanobacteria, algae and yeasts has now been isolated from these habitats which are extreme in terms oftemperature, pH, salinity and pressure as well as species which are resistant to radiation and toxic chemicals. Whilst originally considered to be mere 'scientific curiosities', it is now generally accepted that many have con siderable biotechnological and commercial significance. Recently the term 'extremophile' has been used to describe these organisms. Over the past twenty years extensive studies of the ecology, physiology, taxonomy and molecular biology of these micro-organisms have been undertaken. These have resulted in a complete reassessment of our concept ofmicrobial evolution. The identification ofthe Archaeobacteria as the third kingdom ofliving organisms has given considerable impetus to extremophile research and is presenting many new challenges.
The study of thermoregulation in endotherms has contributed much to the emergence of the concept of control theory in biology. By the same token, the study of tempera ture adjustment in ectotherms is likely to have a far-reaching influence on ideas on the regulation of metabolism in general. The reason for this is that ectotherms, in adapting to the vagaries of a thermally unstable environment, deploy a range of subtle molecular and organismic strategies. Thus the experimenter, using temperature changes as a tool, is well equipped to analyze some of these strategies. This approach has enabled some important mechanisms of temperature-induced adaptation to be elucidated; the most striking of these are the effects on metabolism of changes in the conformation of enzymes and the transfer properties of membranes. Furthermore, there is a vague but persistent feeling among those working in this field that changes in the nervous system will ultimately prove to be the agency by which many of the molecular mechanisms of temperature adaptation are controlled. Should this indeed be the case, a new phase would soon begin in our understanding of the interactions between the systemic and the cellular levels of organization. However, it is not only questions about the causes of temperature adaptation that can provide answers of potential importance to the general biologist; of equal significance are questions as to the meaning of temperature adaptation in a particular organism.
