[The effect of electromagnetic fluctuations in the decimeter range on the processes of the body adaptation of athletes to physical loads].
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Adaptation, Physiological↗
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The effect of adaptive mutagenesis on genetic variation at a linked, neutral locus.
Based on recent studies in single-celled organisms, it has been argued that a fitness benefit associated with a mutation will increase the probability of that mutation occurring. This increase is independent of mutation rates at other loci and is called adaptive mutagenesis. We modeled the effect of adaptive mutagenesis on populations of haploid organisms with adaptive mutation rates ranging from 0 to 1 x 10(-5). Allele frequencies at the selected locus and a neutral linked locus were tracked. We also observed the amount of linkage disequilibrium during the selective sweep and the final heterozygosity after the sweep. The presence of adaptive mutagenesis increases the number of genetic backgrounds carrying the new fitter allele, making the outcomes more representative of the population before the selection. Therefore, more neutral genetic variation is preserved in simulations with adaptive mutagenesis than in those without it due to hitchhiking. Since adaptive mutagenesis is time-dependent, it can generate mutants when other mechanisms of mutation cannot. In addition, adaptive mutagenesis has the potential to confound both phylogeny construction and the detection of natural selection from patterns of nucleotide variation.
Adaptation, Physiological↗
Uptake of inorganic carbon by isolated chloroplasts from air-adapted dunaliella.
Neither Dunaliella cells grown with 5% CO(2) nor their isolated chloroplasts had a CO(2) concentrating mechanism. These cells primarily utilized CO(2) from the medium because the K((0.5)) (HCO(3) (-)) increase from 57 micromolar at pH 7.0 to 1489 micromolar at pH 8.5, where as the K((0.5)) CO(2) was about 12 micromolar over the pH range. After air adaptation for 24 hours in light, a CO(2) concentrating mechanism was present that decreased the K(0.5) (CO(2)) to about 0.5 micromolar and K(0.5) (HCO(3) (-)) to 11 micromolar at pH 8. These K(0.5) values suggest that air-adapted cells preferentially concentrated CO(2) but could also use HCO(3) (-) from the medium. Chloroplasts isolated from air-adapted cells had a K((0.5)) for total inorganic carbon of less than 10 micromolar compared to 130 micromolar for chloroplasts from cells grown on high CO(2). Chloroplasts from air-adapted cells, but not CO(2)-grown cells, concentrate inorganic carbon internally to 1 millimolar in 60 seconds from 240 micromolar in the medium. Maximum uptake rates occurred after preillumination of 45 seconds to 3 minutes. The CO(2) concentrating mechanism by chloroplasts from air-adapted cells was light dependent and inhibited by 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) or flurocarbonyl-cyamidephenylhydrazone (FCCP). Phenazine-methosulfate at 10 micromolar to provide cyclic phosphorylation partially reversed the inhibition by DCMU but not by FCCP. One to 0.1 millimolar vanadate, an inhibitor of plasma membrane ATPase, inhibited inorganic carbon accumulation by isolated chloroplasts. Vanadate had no effect on CO(2) concentration by whole cells, as it did not readily cross the cell plasmalemma. Addition of external ATP to the isolated chloroplast only slightly stimulated inorganic carbon uptake and did not reverse vanadate inhibition by more than 25%. These results are consistent with a CO(2) concentrating mechanism in Dunaliella cells which consists in part of an inorganic carbon transporter at the chloroplast envelope that is energized by ATP from photosynthetic electron transport.
Journal Article↗
Weaning of three hybridoma cell lines to serum free low protein medium.
A general weaning procedure is described which allowed a range of hybridomas to be weaned readily off serum without loss of antibody production. Initial work was carried out with one cell line only (SPO1 cells) and one serum substitute containing a final protein concentration of 40 mg l-1. The SPO1 cells were first adapted to a range of readily available basal media and then weaned off serum by a range of protocols. From this work an optimal weaning protocol and basal medium for weaning were determined. These were then used to wean the SPO1 cells and two other cell lines off serum with a second, protein free, serum substitute with varying concentrations of defined proteins added. All three cell lines investigated were readily weaned off serum by this protocol at protein concentrations as low as 1 mg l-1. No loss of antibody production was observed with any of the cell lines. The weaning procedure outlined in both simple and rapid and has been successfully adopted in our laboratory by relatively inexperienced cell culture technicians.
Animals↗
Human mate guarding.
Long-term committed mating is a fundamental strategy in the human repertoire. Successful enactment of this strategy requires solving two related adaptive problems--fending off potential mate poachers and preventing a mates from defecting. Mate guarding adaptations evolved to solve these persistent problems. Those who failed in mate guarding risked suffering substantial reproductive costs ranging from genetic cuckoldry to reputational damage to the entire loss of a mate. Because the precise nature of the adaptive problems confronted differed historically for the sexes, men and women evolved corresponding differences in the underlying psychology of mate guarding. Men's mate guarding, relative to that of women's, is strongly triggered as a consequence of being mated to young and physically attractive women, being confronted by interested rivals who have superior economic resources or prospects, and having a mate who displays signs of sexual involvement with a rival. Women's mate guarding, relative to that of men's, is triggered as a consequence of being mated to men high in income and status striving, rivals who are more physically attractive, and having a partner who shows signs of emotional involvement with another woman. Behavioral output of mate guarding adaptations range from vigilance to violence.
Behavior Control↗
Effects of adaptation to apparent movement on recovery of structure from motion.
Past work on the recovery of three-dimensional structure from dynamic two-dimensional images has led to inconsistent conclusions regarding the contributions of the short-range and long-range motion processes. In the present experiments, subjects adapted to displays (either four lines or 50 randomly positioned pixels) whose spatiotemporal parameters were chosen to favor either the short-range or long-range process. Adaptation periods were followed by test displays that simulated the rotation of a four-pixel random object about the vertical gamma-axis. The dependent measure was the angle of rotation between successive frames of the rotation display at which percepts of three-dimensional structure broke down. Both the original data and derived measures based on best-fitting polynomials showed small but consistent effects: Compared to control conditions, adaptation to short-range motion reduced the angle at which percepts of structure broke down; adaptation to long-range motion increased them. It is suggested that both low-level (i.e. short-range) and high-level (long-range) processes contribute to the recovery of structure from motion.
Adaptation, Ocular↗
Perceptual manifestations of fast neural plasticity: motion priming, rapid motion aftereffect and perceptual sensitization.
Visual neurons show fast adaptive behavior in response to brief visual input. However, the perceptual consequences of this rapid neural adaptation are less known. Here, we show that brief exposure to a moving adaptation stimulus-ranging from tens to hundreds of milliseconds-influences the perception of a subsequently presented ambiguous motion test stimulus. Whether the ambiguous motion is perceived to move in the same direction (priming), or in the opposite direction (rapid motion aftereffect) varies systematically with the duration of the adaptation stimulus and the adaptation-test blank interval. These biases appear and decay rapidly. Moreover, when the adapting stimulus is itself ambiguous, these effects are not produced. Instead, the percept for the subsequent test stimulus is biased to the perceived direction of the adaptation stimulus. This effect (perceptual sensitization) builds gradually over the time between the adaptation and test stimuli. Our results indicate that rapid adaptation plays a role mainly within early motion processing, whereas a slow potentiation controls the sensitivity at a later stage.
Adaptation, Physiological↗
Morphological features and activation patterns of motor units.
The force that a muscle exerts depends on which motor units have been recruited and at what rate they are discharging action potentials. Because of differences in motor-unit morphology (innervation ratio, average cross-sectional area, specific force, and geometric distribution of muscle fibers), the maximum motor-unit force within a motor-neuron pool is not constant but rather can vary by approximately 50 times. Consequently, muscle force is affected by which motor units have been activated. Similarly, the rate at which a motor neuron discharges action potentials depends on the pattern and quantity of the synaptic input it receives and its intrinsic frequency-current relation. The force that a single motor unit can exert will vary by approximately 3 to 15 times when discharge rate is increased from a minimum to a maximum. In the performance of voluntary contractions, therefore, humans appear to have an infinite number of combinations of motor-unit recruitment and discharge rate that can be used to vary muscle force. However, control strategies have evolved that reduce these options substantially. From experiments on low-force, isometric contractions, it appears that the recruitment order of motor units is relatively fixed and that muscle force is graded by concurrent variations in recruitment and discharge rate over much of the force range. Whereas the recruitment order of motor units appears to be robust in other tasks also, perhaps with the exception of lengthening contractions, the use of discharge rate to grade muscle force seems more variable. When subjected to acute and chronic challenges, motor-unit properties can adapt within limited ranges, and motor-unit discharge rate appears to be more affected than recruitment order, although the extent of recruitment may be affected by changes in use. Because movement is controlled by motor-unit activity, an understanding of motor-unit physiology can have a significant impact on the evaluation and treatment of movement disorders.
Adult↗
Adaptation and constraint in the evolution of Drosophila melanogaster wing shape.
We have taken advantage of parallel instances of natural selection on body size in Drosophila melanogaster to investigate constraints and adaptation affecting wing shape. Using recently developed techniques for statistical shape analysis, we have examined variation in wing shape in similar body size clines on three continents. Gender-related shape differences were constant among all populations, suggesting that gender differences represent a developmental constraint on wing shape. In contrast, the underlying shape varied significantly between continents and shape change within each cline (i.e., between small and large body size populations) also varied between continents. Therefore, variation at these two levels presumably results from either drift or natural selection. Functional considerations suggest that shape variation between the continents is unlikely to be adaptive. However, cline-related shape change, which we show has a significant allometric component, may be adaptive. The overall range of wing shape variation, across a large range of wing size, is extremely small, and the possibility that wing shape is subject to stabilizing selection (or canalization) is discussed.
Adaptation, Physiological↗
Adipose tissue as an endocrine and paracrine organ.
The discovery of leptin has imparted great impetus to adipose tissue research by demonstrating a more active role for the adipocyte in energy regulation. Besides leptin, however, the adipose tissue also secretes a large number other signals. Cytokine signals, TNFalpha and IL-6, and components of the alternative pathway of complement influence peripheral fuel storage, mobilization and combustion, as well as energy homeostasis. In addition to the acute regulation of fuel metabolism, adipose tissue also influences steroid conversion and sexual maturation. In this way, adipose tissue is an active endocrine organ, influencing many aspects of fuel metabolism through a network of local and systemic signals, which interact with the established neuroendocrine regulators of adipose tissue. Thus, insulin, catecholamines and anterior pituitary endocrine axes interact at multiple levels with both cytokines and leptin. It may be proposed that the existence of this network of adipose tissue signalling pathways, arranged in an hierarchical fashion, constitutes a metabolic repertoire which enables the organism to adapt to a range of different metabolic challenges, including starvation, reproduction, times of physical activity, stress and infection, as well as short periods of gross energy excess. However, the occurrence of more prolonged periods of energy surplus, leading to obesity, is an unusual state in evolutionary terms, and the adipose tissue signalling repertoire, although sophisticated, adapts poorly to these conditions. Rather, the responses of the adipose tissue endocrine network to obesity are maladaptive, and lay the foundations of metabolic disease.
Adipose Tissue↗
Adaptive changes related to medication treatment of ADHD: listening to parents of children in clinical trials of a novel nonstimulant medication.
The DSM-IV diagnostic criteria for attention-deficit/hyperactivity disorder (ADHD) have proved useful in providing a common language for diagnosing, treating, and researching the disorder. Despite the utility of current ADHD diagnostic criteria, sophisticated theoretical conceptualizations of the etiology of ADHD have described a much more complex disorder that includes a range of neuropsychological impairments (such as working memory deficits and other executive dysfunction) and underlying structural and functional neuropathology (e.g., caudate nucleus volume, frontal lobe activity). Inattention, hyperactivity, and impulsivity, the hallmark triumvirate symptoms of ADHD, may be better viewed as some of the many meaningful symptoms with roots in executive-functioning impairment. Outcomes of brain-imaging studies, public skepticism about diagnosis and treatment, and a demand for meaningful clinical outcomes of treatment point to a considerable need to broaden treatment-outcome criteria beyond the DSM-IV domains. The wide-ranging decrements in adaptive function and quality of life reported by parents of children diagnosed with ADHD further support core executive dysfunction. Emerging findings concerning medication-related improvements in adaptive functioning (e.g., social, emotional, academic), as well as the rapid search for the neuropathology that may underlie these improvements, are fueling interest in the assessment of adaptive function in clinical trials. In a series of ongoing clinical trials of a novel nonstimulant medication for ADHD, many parents reported significant improvements in the lives of their children beyond the DSM-IV criteria. These parental reports, despite their inherent sources of error, underscore the importance of including broader and more meaningful clinical outcome assessment in clinical trials. Research protocols that omit parental interviews that assess adaptive and executive function may well overlook several meaningful and consequential medication-related improvements.
Adolescent↗
Auditory adaptation is differentially impaired in familial and sporadic Alzheimer's disease.
Neurophysiologic measures are particularly sensitive to alterations in attention and arousal. The purpose of this study was to evaluate the auditory adaptation of normal and mildly demented elderly people. We compared the automatic behavior of an auditory evoked potential (N100) in three age-matched groups of elderly subjects, one with familial Alzheimer's disease (AD), one with sporadic AD and one healthy group. All AD subjects corresponded clinically and neuropsychologically with the early stage of dementia. The dynamic range of auditory adaptation is known to be related to age, and normal auditory adaptation for the age was observed in our healthy aged and sporadic AD subjects, whereas the familial AD subjects lacked normal adaptation. The familial AD subjects also showed statistically significantly smaller peak amplitudes and shorter latencies of the N100 throughout the habituation test. This persistent difference in automatic habituation of sensory responses supports the view that different subtypes of AD are differentially affected. The observed differences give an objective measure of the impaired involuntary adaptive functions of neuronal networks involved in auditory processing in subtypes of AD. Since habituation reflects the most primitive stage of learning and short-term memory, altered habituation may predict faster deterioration of clinical status in the familial group of AD subjects.
Adaptation, Physiological↗
Recovery from short-term adaptation in single neurons in the cochlear nucleus.
Recovery from short-term adaptation was measured in single neurons in the cochlear nucleus using a forward masking stimulus paradigm. The response to a short-duration, low-level probe tone at a unit's characteristic frequency (CF) was measured before and after presentation of a masker tone at the unit's CF. The degree of adaptation was defined as the ratio of firing to the probe in the adapted and unadapted conditions. The level of the masker and time difference between the masker offset and probe onset ('DT') were varied. As DT increased, the response to the probe increased in most Primarylike, Primarylike-notch, and Chopper units. Recovery was approximately linear in log time for most of these units. However, approximately half the Pauser/Buildup and On units showed very different recovery patterns, ranging from no adaptation to very non-linear recovery patterns. The results suggest that little alteration in the recovery process occurs between the auditory nerve and Primarylike, Primarylike-notch, and Chopper units, but that significant changes in the recovery process occur in Pauser-Buildup and On units.
Acoustic Stimulation↗
Nasal respiratory turbinate function in birds.
Nasal respiratory turbinates are complex, epithelially lined structures in nearly all birds and mammals that act as intermittent countercurrent heat exchangers during routine lung ventilation. This study examined avian respiratory turbinate function in five large bird species (115-1,900 g) inhabiting mesic temperate climates. Evaporative water loss and oxygen consumption rates of birds breathing normally (nasopharyngeal breathing) and with nasal turbinates experimentally bypassed (oropharyngeal breathing) were measured. Water and heat loss rates were calculated from lung tidal volumes and nasal and oropharyngeal exhaled air temperatures (T(ex)). Resulting data indicate that respiratory turbinates are equally adaptive across a range of avian orders, regardless of environment, by conserving significant fractions of the daily water and heat budget. Nasal T(ex) of birds was compared to that of lizards, which lack respiratory turbinates. The comparatively high nasal T(ex) of the lizards in similar ambient conditions suggests that their relatively low metabolic rates and correspondingly reduced lung ventilation rates may have constrained selection on similar respiratory adaptations.
Adaptation, Physiological↗
Light adaptation of cone photoresponses studied at the photoreceptor and ganglion cell levels in the frog retina.
The sensitivity and time scale of the dominant (562 nm) cone system of the frog, Rana temporaria, were studied as functions of steady adapting illuminance (IB). Photoreceptor responses to brief flashes of light were recorded as aspartate-isolated ERG mass potentials from the isolated retina. The characteristics of the cone signal after transmission through the retina were derived from response thresholds and stimulus--intensity-response--latency functions for extracellularly recorded spike discharges of single ganglion cells in the eyecup. At 14 degrees C, the single-photon response of dark-adapted cones, extrapolated from ERG intensity-response functions, had an amplitude of 0.5% of the saturated response (Umax) and peaked at tp approximately 0.4 sec. Steady background illumination decreased both tp and flash sensitivity (SF), starting from apparent "dark lights" of, respectively, less than 10 (for time scale) and about 100 (for sensitivity) photoisomerisations per cone per second [P*sec-1]. From there upwards, two distinct ranges of background adaptation were apparent. Under moderate backgrounds (up to IB approximately 10(4) - 10(5) P*sec-1), sensitivity fell according to the relation SF alpha IB-0.64 and time scale shortened according to tp alpha IB-0.16. Under brighter backgrounds, from approx. 10(5) P*sec-1 up to the limit of our light source at 10(7) P*sec-1, the decrease in SF was significantly stronger than predicted by the Weber relation (SF alpha IB-1), while the decrease in tp levelled out and even tended to reverse. All these changes were virtually identical at the photoreceptor and ganglion cell levels, although the absolute time scale of cone signals apparent at the latter level was 2-fold longer. Our general conclusion is that photoreceptors have several distinct regimes for light adaptation, and traditional descriptions of functional changes (in sensitivity and kinetics) relevant to vision need to be restated with higher resolution, in view also of recent insights into the diversity of underlying mechanisms.
Adaptation, Ocular↗
Genomic signatures of the Arctic-adapted North American gray wolf ecotype.
The Arctic Circle is one of Earth's most extreme environments. It features cold temperatures, resource shortages, and near-complete winter darkness. Here, we generated a chromosome-level genome assembly of a male wolf from the Arctic Archipelago (Canis lupus arctos). Our assembly and that of the related C. l. orion from Greenland was used to identify candidate genic and regulatory features of Arctic-adapted polar wolves, ranging from selection acting on standing variation and amino acid changes in genes to conserved non-exonic elements (CNEEs) that may regulate gene expression. We identified genes and nearby CNEEs associated with thermoregulation (e.g., APOB), coat color and patterning (e.g., GOLGB1), and DNA damage response (e.g., POLQ). In vitro assays supported changes in polar wolf gene (POLQ and TRPV2 amino acid substitutions) and CNEE function. Our report offers insights into the genetic mechanisms underlying polar wolf adaptations, laying a foundation for future studies on Arctic canines.
Amino acid substitutions↗
Plasticity in airway smooth muscle: an update.
At a similar meeting 10 years ago, we proposed (i) that the long functional range of some smooth muscles is accommodated by plastic alterations that place more myofilaments in series at longer lengths, (ii) that this plasticity is facilitated by myosin filament evanescence, with filaments dissociating partially during relaxation and reforming upon activation, and (iii) that filament lengthening during the rise of activation would cause velocity to fall. Since that meeting, we have accumulated a substantial body of evidence to support these proposals, as follows: (i) muscles develop nearly the same force when adapted to a range of lengths that can vary by 3-fold; (ii) other physiological parameters including shortening velocity, maximum power, compliance, ATPase rate, and thick-filament mass increase by about 2/3 for a doubling of muscle length; (iii) thick-filament density increases substantially during the rise of activation; and (iv) velocity falls as force rises during the rise of tetanic force, and when correction is made for differences in activation, velocity and force vary exactly in inverse proportion. This review explains the rationale for the different experimental measurements and their interpretation.
Actin Cytoskeleton↗
Host-phage relationships in the genus Mycobacterium and their clinical significance.
Progress made during the last 15 years in the studies on the relationships between mycobacteria and their bacteriophages is reviewed. The basic biology of the phages and the applications of studies on adaptation and host range are discussed in relation to the development of phage typing systems for epidemiological purposes. The nature of lysogeny, its natural occurrence, its experimental establishment, the effect of the lysogenic state on the host bacterium and the evidence that lysogenic mycobacteria are involved in human disease, especially sarcoidosis, is reviewed.
Adaptation, Biological↗