The Antarctic Peninsula is characterized by harsh and dynamic environmental conditions. Organisms inhabiting this environment may be challenged by extremes of low temperature, limited water availability, dramatic seasonal fluctuations of light availability and ultraviolet radiation, and high salinity. This dissertation describes three projects examining the tolerance and physiological responses to such environmental stress of two Antarctic arthropods, the midge Belgica antarctica and the collembolan Cryptopygus antarcticus. The first investigation examined the ability of B. antarctica larvae to resist inoculative freezing at subzero temperatures and instead dehydrate as a strategy for winter survival (i.e., cryoprotective dehydration). When cooled to subzero temperatures in the presence of ice, the body fluid melting point was depressed to near equilibrium with the ambient temperature, due to reductions of body water content and the accumulation of several osmolytes, suggesting larvae can undergo cryoprotective dehydration at subzero temperatures. Under more natural conditions, the use of cryoprotective dehydration versus freeze tolerance for winter survival appears to depend upon the moisture content of the surrounding soil. The purpose of the second study was to assess the tolerance and physiological response to desiccation of C. antarcticus under ecologically-relevant conditions. Slow dehydration at high relative humidities characteristic of the austral summer induced the accumulation of several organic osmolytes and increased the tolerance of water loss. A mild drought acclimation further increased the subsequent desiccation tolerance of C. antarcticus. The springtails were also susceptible to water loss at subzero temperatures and likely rely upon such dehydration as a key component for winter survival. As B. antarctica microhabitats may be periodically inundated with seawater, the final investigation examined the osmotic response and tolerance of larvae to hyperosmotic seawater exposure. The larvae displayed an impressive tolerance of the osmotic stress, as ~50% survived a 6-d submergence in pure seawater. Hyperosmotic stress induced the accumulation of organic osmolytes and resulted in a significant positive correlation between the rate of oxygen consumption and larval body water content. Finally, a brief seawater acclimation enhanced the subsequent tolerance of freezing and dehydration, but reduced the tolerance of heat shock.

While the subject of environmental stress in animals is broad, the available information is fragmentary and lacks an up-to-date overview and analysis. Environmental Stress and Cellular Response in Arthropods fills these knowledge gaps. Written by three experts from the same institution, the chapters have a consistency not often found in multi-authored or contributed books. The authors describe environmental stress in arthropods, specifically Drosophila and analyze the process in all its aspects, from biochemical mechanisms to effects on the whole organism. Incorporating new information that has become available in recent years, the authors explore hypotheses about the integrated response these systems often have. They explore topics ranging from disturbance of homeostasis, changes in metabolic processes, damage of cellular structures to acquired tolerance, effects on aging processes, and survival and cell death. By analyzing all these aspects in detail at the molecular, biochemical, and physiological level of the cell, the authors give you a thorough look at the relationship between an organism and its environment at the cellular level.

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.

Cell and Molecular Responses to Stress is a new multi-volume book series from Elsevier Science that focuses on how organisms respond at a molecular level to environmental stresses imposed upon them. All organisms deal with variations in multiple environmental factors including temperature, oxygen, salinity, and water availability. Many show amazing tolerances to extreme stress with remarkable biochemical adaptations that allow life to persist under very difficult circumstances. This series explores the molecular mechanisms by which cells and organisms respond to stress, focusing on the variations in metabolic response that allow some cells and organisms to deal with extreme stress, others to endure stress within strict limits, and others to have a very low tolerance for changes in environmental parameters.Articles from within the series highlight the elastic limits of molecular responses in Nature, with examples drawn from animal, plant and bacteria systems.Volume 1, begins by considering some of the roles of environmental stress in determining the geographic distribution of animals and in promoting species divergence and then explores gene expression and metabolic responses to environmental stress with examples of adaptation to high and low temperature, osmotic, anoxia/ischemia, desiccation, high pressure and heavy metal stresses.

Insects represent the most abundant and diverse animal group on Earth. The number of described species is more than one million and up to ten million are estimated. Insects have one of the widest distributions in the world because they have adapted to extreme ranges of environments.Molecular ecology studies ecological processes based on the analysi

The study of insects at low temperature is a comparatively new field. Only recently has insect cryobiology begun to mature, as research moves from a descriptive approach to a search for underlying mechanisms at diverse levels of organization ranging from the gene and cell to ecological and evolutionary relationships. Knowledge of insect responses to low temperature is crucial for understanding the biology of insects living in seasonally varying habitats as well as in polar regions. It is not possible to precisely define low temperature. In the tropics exposure to 10-15°C may induce chill coma or death, whereas some insects in temperate and polar regions remain active and indeed even able to fly at O°C or below. In contrast, for persons interested in cryopreservation, low temperature may mean storage in liquid nitrogen at - 196°C. In the last decade, interest in adaptations of invertebrates to low temperature has risen steadily. In part, this book had its origins in a symposium on this subject that was held at the annual meeting of the Entomological Society of America in Louisville, Kentucky, USA in December, 1988. However, the emergence and growth of this area has also been strongly influenced by an informal group of investigators who met in a series of symposia held in Oslo, Norway in 1982, in Victoria, British Columbia, Canada in 1985 and in Cambridge, England in 1988. Another is scheduled for Binghamton, New York, USA (1990).

Nematodes are renowned for their ability to survive severe environmental fluctuations. Their mechanisms to withstand temperature extremes, desiccation, and osmotic and ionic stress are presented here together with information on the underlying biochemical basis contributing to survival. Highlighting parallels and contrasts between parasitic and free-living nematode groups, this book integrates strategies that enable nematodes to persist in the absence of food with tactics used by parasitic forms to survive the defence responses of a plant or animal host. This functional study is an essential resource for researchers in nematology, parasitology and zoology.