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The present conduction calorimeter was assembled to study the thermogenesis of whole organs or little Vertebrates. It is constituted of three essential parts : one aluminium calorimetric block, two cylindrical cells in plexiglass of 60,80 or 100 ml volume, two flux plates : the sensitive elements which permit differential measurements on a chart recorder. The whole system is thermoregulated.
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Many archaea are extremophiles. They thrive at high temperatures, at high pressure and in concentrated acidic environments. Nevertheless, the largest proportion and greatest diversity of archaea exist in cold environments. Most of the Earth's biosphere is cold, and archaea represent a significant fraction of the biomass. Although psychrophilic archaea have long been the neglected majority, the study of these microorganisms is beginning to come of age. This review casts a spotlight on the ecology, adaptation biology and unique science that is being realized from studies on cold-adapted archaea.
Understanding the architecture of biological adaptations is a major endeavor of evolutionary biology. Using Natural History collections, we study the genetic basis and evolution of white/brown winter coat color variation in the long-tailed weasel (Neogale frenata), a crucial phenological adaptation for camouflage in habitats with seasonal snow. We produced whole-genome sequencing data for museum specimens, along two winter color morph transition areas in North America, at the West and East coasts. Genome-wide association scans identified a single genomic region linked to color variation polymorphism with approximately 300 kb and 200 kb in the West and East regions, respectively, which included the pigmentation gene MC1R. We identified three MC1R alleles, two of which with deletions of nine or eight amino acids, alternatively associated with the winter brown morphs in the West and East, respectively. These deletions affect the second transmembrane domain, and in one case also the first extracellular loop, which in silico analyses predicted to impact the protein's function. Our findings show alternative intraspecific evolutionary solutions for environmental adaptation in long-tailed weasels, building on the evidence that major genes of the melanin production pathway are hotspots for recurrent and independent evolution of winter camouflage adaptation. This adaptive variation may be crucial to anchor adaptive responses facing future environmental change.
The advent of molecular biology techniques has profoundly changed pathophysiological concepts of myocardial hypertrophy and overload-induced heart failure. Heart failure is a consequence of the limits and imperfection of biological adaptation to mechanical overload. Factors including fibrosis, senescence, ischemia, inflammation, catabolism and hormonal response may contribute to myocardial dysfunction. In humans changes in the genes coding for myosin are observed only in the atrial myocardium, in association with diastolic left ventricular function. In most animal species, alteration in proteins involved in intracellular calcium movement and autonomic nervous dysfunction are responsible for both reduction of Vmax and arrhythmias associated with myocardial hypertrophy. Moreover, myocardial fibrosis is a major determinant of enhanced left ventricular stiffness and arrhythmogenicity.
Endosymbioses between chemosynthetic bacteria and marine invertebrates are remarkable biological adaptations to life in sulfide-rich environments. In these mutualistic associations, sulfur-oxidizing chemoautotrophic bacteria living directly within host cells both aid in the detoxification of toxic sulfide and fix carbon to support the metabolic needs of the host. Though best described for deep-sea vents and cold seeps, these symbioses are ubiquitous in shallow-water reducing environments. Indeed, considerable insight into sulfur-oxidizing endosymbioses in general comes from detailed studies of shallow-water protobranch clams in the genus Solemya. This review highlights the impressive body of work characterizing bacterial symbiosis in Solemya species, all of which are presumed to harbor endosymbionts. In particular, studies of the coastal Atlantic species Solemya velum and its larger Pacific congener Solemya reidi are the foundation for our understanding of the metabolism and physiology of marine bivalve symbioses, which are now known to occur in five families. Solemya velum, in particular, is an excellent model organism for symbiosis research. This clam can be collected easily from coastal eelgrass beds and maintained in laboratory aquaria for extended periods. In addition, the genome of the S. velum symbiont is currently being sequenced. The integration of genomic data with additional experimental analyses will help reveal the molecular basis of the symbiont-host interaction in Solemya, thereby complementing the wide array of research programs aimed at better understanding the diverse relationships between bacterial and eukaryotic cells.
The adaptive response of soil biological nitrification to Zn and Pb was assessed using an in situ method we have developed. The method is based on reinoculating a sterilized metal contaminated soil with the same soil that is either uncontaminated or has been incubated with metal. This approach excludes the potentially confounding effects of metal aging reactions in soils. We found added Zn concentrations which gave rise to a decrease in nitrification to 50% that of the uncontaminated soil (i.e. EC50) of 210 mg/kg for communities not previously exposed to Zn and 850 mg/kg for communities exposed to Zn for 17 months, indicating that significant adaptation of the community to Zn had occurred. Similarly, this protocol was able to demonstrate adaptation of soil biological nitrification to Pb, with EC50 values of 1960 and 3150 mg/kg for the unexposed and exposed treatments, respectively. Exposure of unadapted and adapted microbial communities to a combination of Zn and Cd showed that the presence of Cd did not lead to greater toxicity in either community. Adapted communities were not more sensitive to decreases in soil pH than unadapted communities. Prior exposure to Zn was found to confer significantly greater tolerance of the community to Pb. Prior exposure to Pb similarly conferred significantly greater tolerance of the community to Zn. Implications of the adaptive capacity of soil microbes to the development of critical threshold values for heavy metals in soil based on ecotoxicity assessments are discussed.
By combining appearance and behavior in animals with physical laws, we can get an understanding of the adaptation and evolution of various structures and forms. Comparisons can be made between animal bodies and various technical constructions. Technical science and theory during the latest decades have resulted in considerable insight into biological adaptations, but studies on structures, forms, organs, systems, and processes in the living world, used in the right way, have also aided the engineer in finding wider and better solutions to various problems, among them in the design of micro-air vehicles (MAVs). In this review, I discuss the basis for flight and give some examples of where flight engineering and nature have evolved similar solutions. In most cases technology has produced more advanced structures, but sometimes animals are superior. I include how different animals have solved the problem of producing lift, how animal wings meet the requirements of strength and rigidity, how wing forms are adapted to various flight modes, and how flight kinematics are related to flight behavior and speed. The dynamics of vorticity is summarized. There are a variety of methods for the determination of flight power; it has been estimated adequately by lifting-line theory, by physiological measurements, and from mass loss and food intake. In recent years alternative methods have been used, in which the mechanical power for flight is estimated from flight muscle force used during the downstroke. Refinements of these methods may create new ways of estimating flight power more accurately. MAVs operate at the same Reynolds numbers as large insects and small birds and bats. Therefore, studies on animal flight are valuable for MAV design, which is discussed here.
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The objective of this manuscript is to propose an integrative conceptual model linking depressive disorders and depressive symptoms. Existing conceptual models of depression etiology tend to make this distinction in an arbitrary way. For example, in the current edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV), there is a requirement that severe and persistent depressive symptoms be present for a period of two weeks or more before the depressive syndrome qualifies as a major depressive disorder. The concept of psychosocial stress is a potentially unifying concept relating depressive symptoms to disorders, as stress is a risk factor for both depressive symptoms and depressive disorders. Furthermore, a key feature of the depressive disorders is that they are associated with psychosocial dysfunction, which may be conceptualized as an inability to adapt to environmental stress. The hypothesis presented here is that subclinical depressive symptoms represent an adaptive biological response pattern to psychosocial stress, fostering adaptation in the face of a changing (stressful) environment. However, when a threshold of symptom severity is exceeded, the depressive syndrome becomes maladaptive, impairing adaptation to environmental stress and leading to an accumulation of stressful circumstances and experiences. As such, a vicious cycle may be created, leading, perhaps, to the occurrence of a depressive disorder.
There were some disputes about the concept and mechanism of biological evolution. This paper tried to give more explanations on the key concepts. The biological adaptability was distinguished into two different concepts: biological evolution and specialization. The former was defined as the process of biologically gradual evolvement, and the latter was considered as the process of species formation at horizontal development. Moreover, a new conceptual framework was applied to the popular biological theories known by people, and the previous research results or discoveries were explained over again.
Adaptive management of renewable biotic resources accounts explicitly for uncertainties in system responses to management and recognizes the importance of reducing uncertainties while pursuing other management goals. An adaptive approach to the harvest of wildlife populations that are subject to (1) uncontrollable environmental variation, (2) uncertainties about the appropriate characterization of resource dynamics, (3) limitations on the controllability of harvest rates, and (4) uncertainties as to population status, expressed as sampling variation in the monitoring of populations and habitats, is described. Adaptive management is framed in terms of maximizing long-term harvest value against a background of various kinds and degrees of uncertainty, with an emphasis on structural uncertainty. By an appropriate extension of the "system state," adaptive optimization can be defined in terms of Markov decision processes. Solution algorithms are described for systems that are subject to structural uncertainty and are either partially or completely observable. Adaptive optimization is illustrated with an example in waterfowl harvest management that incorporates uncertainty in the relationship between harvest rates and survivorship.
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Neuropsychology has customarily taken a molecular and myopic view of executive functioning, concentrating largely on those proximal processes of which it may be comprised. Although commendable as a starting point, such an approach can never answer the question, "Why executive functioning?" The present paper encourages neuropsychologists to contemplate the longer-term, functional nature of the executive functions (EFs), using an evolutionary perspective. For purely illustrative purposes, a previously developed model of the EFs is briefly presented and is then examined from an evolutionary perspective. That model views the EFs as forms of behavior-to-the-self that evolved from overt (public) to covert (private) responses as a means of self-regulation. That was necessary given the interpersonal competition that arises within this group-living species. The EFs serve to shift the control of behavior from the immediate context, social others, and the temporal now to self-regulation by internal representations regarding the hypothetical social future. The EFs seem to meet the requirements of a biological adaptation, being an improbable complex design for a purpose that exists universally in humans. Discovering the adaptive problems that the EFs evolved to solve offers an invaluable research agenda for neuropsychology lest that agenda be resolved first by other scientific disciplines. Some adaptive problems that the EFs may have evolved to solve are then considered, among them being social exchange (reciprocal altruism or selfish cooperation), imitation and vicarious learning as types of experiential theft, mimetic skill (private behavioral rehearsal) and gestural communication, and social self-defense against such theft and interpersonal manipulation. Although clearly speculative at the moment, these proposals demonstrate the merit of considering the larger adaptive problems that the EFs evolved to solve. Taking the evolutionary stance toward the EFs would achieve not only greater insight into their nature, but also into their assessment and into those larger adaptive capacities that may be diminished through injury or developmental impairment toward that system.