Catálogo de publicaciones - libros

All biological processes of life on Earth experience varying degrees of pressure. Aquatic organisms living in the deep-sea, as well as chondrocytic cells of articular cartilage are exposed to hydrostatic pressures that rise up to several hundred times that of atmospheric pressure. In the case of marine larvae that disperse through the oceanic water column, pressure changes might be responsible for stress conditions during development, limiting colonisation capabilities. In a number of biological systems, life strategies may be significantly influenced by pressure. In this review, we will focus on the consequences of pressure changes on various biological processes, and more specifically on animals living in the deep-sea. Revisiting general principles of pressure effects on biological systems, we present recent data illustrating the diversity of effects pressure may have at different levels in biological systems, with particular attention to effects on gene expression. After a review of the main pressure equipments available today for studying species living naturally at high pressure, we summarise what is known concerning pressure impact during animal development.

The Arctic and the Antarctic differ by age and isolation of the respective marine faunas. Antarctic fish are highly stenothermal, in response to stable water temperatures, whereas the Arctic ones are exposed to seasonal and latitudinal temperature variations. The knowledge of the mechanisms of phenotypic response to cold exposure in species of both polar habitats offers fundamental insights into the nature of environmental adaptation. In the process of cold adaptation, the evolutionary trend of Antarctic fish has led to unique specialisations, including modification of haematological characteristics, e.g. decreased amounts and multiplicity of haemoglobins.

Unlike Antarctic Notothenioidei, Arctic teleosts have high haemoglobin multiplicity. Although the presence of functionally and structurally distinct haemoglobins is a plesiomorphic condition for many perciform-like fishes, it seems that the oxygen-transport system of teleost fish in the Arctic region has been adjusted to temperature differences and fluctuations of Arctic waters, much larger than in the Antarctic. The amino-acid sequences used to gain insight into the evolution history of α and β globins of polar fish have clearly shown that Antarctic and Arctic globins have different phylogenies, leading to the hypothesis that the selective pressure of environment stability allows the phylogenetic signal to be maintained in the Antarctic sequences, whereas environmental variability would tend to disrupt this signal in Arctic sequences.

Organisms from yeast to mammals contain cysteine-rich, heavy metal binding proteins termed metallothioneins. The putative roles of these proteins are trace metal homeostasis and detoxification of poisonous heavy metals. The highly conserved chemical composition and the structural constraints led to the conclusion that metallothioneins of different origin must display remarkably similar features. The present review aims at surveying the studies carried out on the metallothioneins of Antarctic Notothenioidei, a dominating fish group endowed of a number of striking adaptive characters, including reduced (or absent) hematocrit and presence of antifreeze glycoproteins. Given the unique peculiarities of the Antarctic environment, a comparative study of the features of notothenioid metallothioneins could provide new insights into the role of these proteins in physiology and toxicology. The results summarized here show that the metallothioneins of this fish group display a number of features at the level of evolution, expression pattern, structure and function remarkably different from those of mammal metallothioneins.

The recognition of the important role of the polar habitats in global climate changes has awakened great interest in the evolutionary biology of the organisms that live there, as well as the increasing threat of loss of biological diversity and depletion of marine fisheries. These organisms are exposed to strong environmental constraints, and it is important to understand how they have adapted to cope with these challenges and to what extent adaptations may be upset by current climate changes. Adaptations of the dominant group of Antarctic fish, the suborder Notothenioidei, have been thoroughly investigated by several teams. Considering the amount of information available on cold adaptation, the study of fish adapted to the extreme conditions of the polar seas will allow us to gain invaluable clues on the development, impact and consequences of climate and anthropogenic challenges, with powerful implications for the future of the Earth.

This paper reviews literature on psychosocial adaptation in isolated and confined extreme (ICE) environments, focusing on polar work groups and expedition teams, and simulation and actual space crews. Long-duration missions may involve chronic exposure to many stressors that can negatively impact behavioral health, performance and even safety. In the last decades, anecdotal evidence has been replaced by scientific studies, identifying temporal, social, and individual determinants of psychosocial adaptation, and pointing to countermeasures that may minimize or prevent potential problems. Still, many issues remain that require additional investigation, specifically in relation to the integration of psychosocial and neurobiological adaptation. A recognition of ICE environments as natural laboratories for studies of fundamental questions within psychology may attract more scientists to the field.

This paper will first review the issue of hypometabolism in mammals with a focus on the strategies these animals evolved to cope with life challenge in hostile environments (e.g., cold weather and/or shortage of food). The different types of natural hypometabolism (hibernation, torpor, winter sleep) will be briefly described as well as major adaptations in body temperature, and energy and cell metabolism. In the second part of this review the issue of inducing a hypometabolic state in mammals will be afforded with special attention paid to changes in body temperature and metabolism, regulation of gene expression and the possible role of hibernation inducing factors. Finally, an overview of the potential of inducing a hypometabolic state in the human as related to the broad field of biomedicine will be given.

Extreme environments are defined as the opposite of usual environments where the evoked physiological responses are unperceivable, repeatable and adjusted to the constraint. Adaptation strategies to a given environment show three levels: , where a buffer space is built to protect the organism from the hostile milieu, , where temporary adaptive mechanisms are developed, and , where full adaptation is possible with normal life and reproduction. The cost of adaptation increases from the genetic level (minimal cost) to the technological level. These concepts are illustrated by the example of adaptation to altitude hypoxia. The technological level is given by the use of oxygen bottles by high altitude climbers. The physiological level involves various physiological and biological systems (increase in heart rate, ventilation, erythropoiesis, expression of hypoxia-inducible factors, etc.). The genetic level has been reached by some animal species such as Yaks, Llamas, Pikas but has not yet been demonstrated in humans. Diseases developed during exposure to acute or chronic hypoxia may be considered as “adaptive crises” that mimic the transition to a lower energy level of adaptation.

This work is focused on deserts, as extreme environments, because the year 2006 has been declared Year of Deserts and Desertification by the United Nations (IYDD Program 2006). The loss of vital resources such as fresh water and soil, and the depletion of biodiversity are emerging hazards, able to transform beneficial situations into extreme environments. Desertification is generated by land degradation: the loss of biological productivity is caused by nature or by human-induced factors and climate change. Nearby the desertification process there is the increasing process of salinisation of soil and water, induced by irrigation itself, or by salt water ingress derived by tsunamis or hurricanes. Increased research on the development of salt-tolerant cultivars could, with appropriate management, result in the broader use of saline soils. Although careful application is necessary, the combination of sand, seawater, sun and salt-tolerant plants presents a valuable opportunity for many developing countries. Cooperation among plant ecologists, plant physiologists, plant breeders, soil scientists, and agricultural engineers could accelerate the development of economic salt tolerant crops. If saline water is available, the introduction of salt tolerant plants in poor regions can improve food or fuel supplies, increase employment, help stem desertification, and contribute to soil reclamation.