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PubMed1982

Range of modulation of light sensitivity by accessory pigments in the crayfish compound eye.

The compound eye of the crayfish during dark adaptation undergoes an enhancement of light sensitivity within a range of 3 log units. Only 1 log unit can be explained by the increase in responsiveness of the retinula cells. The rest can be accounted for by the migration of the proximal and distal accessory pigments. In isolated retinas, with the distal pigment paralysed in light-adapted position and the proximal pigment only partially responsive, the sensitivity enhancement in darkness is reduced in more than 1 log unit. By hormonally inducing the expansion of the distal pigment while the rest of the system remains dark-adapted, there is a shift of one log unit in the V-log 1 curve. In a crayfish mutant devoid of the two dark accessory pigments, the sensitivity enhancement in dark adaptation only covers one log unit.

Animals↗

PubMed2006

The therapeutic relationship in the brief treatment of depression: contributions to clinical improvement and enhanced adaptive capacities.

Using data from the National Institute of Mental Health Treatment for Depression Collaborative Research Program, the authors examined the impact on treatment outcome of the patient's perception of the quality of the therapeutic relationship and contribution to the therapeutic alliance. Shared variance with early clinical improvement was removed from these relationship measures. Multilevel modeling demonstrated that a perceived positive therapeutic relationship early in treatment predicted more rapid decline in maladjustment subsequent to the relationship assessment. This effect occurred equally across all 4 treatment conditions. A positive early therapeutic relationship also predicted better adjustment throughout the 18-month follow-up as well as development of greater enhanced adaptive capacities (EAC). Controlling a wide range of patient characteristics did not eliminate the effects of the therapeutic relationship on rate of improvement during treatment and on EAC. Thus, independent of type of treatment and early clinical improvement, the therapeutic relationship contributes directly to positive therapeutic outcome.

Adaptation, Psychological↗

PubMed2001

Prey catching in the archer fish: angles and probability of hitting an aerial target.

When trying to squirt down aerial arthropods, archer fishes (Toxotidae) have to cope with the displacement of the image of the target by refraction of light at the water surface. It has been suggested, and accepted, that Toxotes jaculatrix would avoid the effect of refraction by squirting vertically. In our previous study, however, Toxotes chatareus was observed to squirt under a wide range of angles, including angles much smaller than 90 degrees. The aim of the present study was to asses in T. chatareus (N=15), the frequency distribution of angles used, the relation between angle and probability to hit, the relation between target height and angle, and the smallest angles the fishes can use. The outcome was a distribution with a range of 102-58 degrees and a median of 74 degrees, no relation between angle and probability to hit, no relation between target height and angle and a smallest angle of 45 degrees. The results clearly indicate that T. chatareus does not evade the refraction effect by squirting only vertically (90 degrees ), but masters a considerable refraction effect thanks to a mechanism that is not investigated here. The capacity to hit prey under a wide range of angles is seen as an important adaptation to the natural habitat where the visibility of prey is restricted by vegetation. The constraints of the range of angles are discussed.

Journal Article↗

PubMed1998

Tonic efferent-induced cochlear damping in roosting and echolocating mustached bats.

The activity of the medial olivocochlear (MOC) efferent system in mustached bats, Pteronotus p. parnellii, was studied by monitoring changes in the mechanical properties of the cochlea. The changing properties were expressed by the decay time (DT) of cochlear microphonic potentials produced by transient-induced ringing (Henson et al., 1995). Tape-recorded roost noise (biosonar and communication sounds) produced sudden, marked decreases in DT when presented to the contralateral ear of animals adapted to the quiet. When the animals were first removed from their roosts the DT was relatively short (1.2-1.5 ms) but this gradually lengthened by about 0.5-1.0 ms as they rested in a quiet chamber. The time required to reach a stable, quiet-adapted state after noise exposure varied with SPL and exposure time; in many experiments recovery was in the range of 90-120 min. When quiet-adapted bats were isolated and allowed to fly and echolocate for 20 min, the DTs measured within a few minutes after the end of the flight were also short and only slowly returned to longer preflight values. The administration of a single dose of gentamicin, which blocks MOC effects, greatly reduced the amount of suppression (damping) observed after periods of noise and echolocation sound exposure. We conclude that tonic MOC activity is induced by the natural vocalizations and roost noise and this activity probably regulates and protects the highly resonant cochlear partition.

Adaptation, Physiological↗

PubMed1982

Static an dynamic activity of cold receptors in cats after long-term exposure to various temperatures.

Ten cats were adapted for 4.7 years in a climatic chamber to an ambient temperature of 5 degree C an 8 cats to 30 degree C under artificial illumination and food ad libitum., Cats living at 5 degree C had 15.2 +/- 0.5 mean nasal and 38.0 +/- 0.3 degree C mean rectal temperature; the corresponding values for cats living at 30 degree C were 31.0 +/- 0.4 degree an 38.3 +/- 0.1 degree C. Static and dynamic activities of single specific cold fibers from the nose were recorded when applying static temperature of 40, 35, 30, 25, 20, 15 and 10 degree C and dynamic cooling steps of 5 degree C starting from static temperature between 40 and 15 degree C. In each group, a population of 100 cold fibers was examined. The average static frequencies between 35 and 20 degree C slightly but not significantly lower in the cold adapted group, the respective values for both groups at 30 degree C being 5.6 and 5.6s-1. The average dynamic maxima were considerably lower in the cold adapted group throughout the whole temperature range, the values at 30 degree C being 44 and 61s-1, respectively. The difference between the dynamic frequency-temperature curves of both fiber populations was highly significant (P less than 0.001). The distribution of static maxima of individual cold fibers as well as the distribution of fibers with static bursts was nearly identical for both groups, whereas the distribution of dynamic maxima and dynamic bursts was significantly shifted lower temperatures in the could adapted group. Seven sub-groups of cold fibers were formed according to their static maximum at temperatures between 40 and 10 degree C. The most pronounced adaptive modification was a significantly lower dynamic peak frequency of the sub-groups with static maxima at 15, 20, 25, 35 and 40 degree C in the cold adapted animals.

Adaptation, Physiological↗

PubMed1977

Increased intracellular sodium mimics some but not all aspects of photoreceptor adaptation in the ventral eye of Limulus.

The effects of the intracellular iontophoretic injection of Na+ ions have been quantitatively compared with adaptation in ventral photoreceptors of Limulus. We find that: (a) both light adaptation and sodium injection are associated with a decrease in the variability of the threshold response amplitued; (b) both light adaptation and sodium injection are associated with a decrease in the absolute value of the temporal dispersion of the threshold response time delay; (c) the same template curve adequately fits the intensity response relationships measured under light adaptation and Na+ injection; (d) both light adaptation and Na+ injection produce a fourfold decrease in response time delay for a desensitization of 3 log units; (e) the time coures of light adaptation and dark adaptation is significantly faster than the onset of and recovery from desensitization produced by Na+ injection; (f) unlike local illumination, Na+ injection does not produce localized desensitization of the photoreceptor. These findings suggest that a rise in intracellular Na+ concentration makes at most only a minor contribution (probably less than 5%) to the total adaptation of these receptors in the intensity range we have examined (up to 3 log units above absolute threshold). However, changes in intracellular Na+ concentration may contribute to certain components of light and dark adaptation in these receptors.

Action Potentials↗

PubMed1999

Physiological disturbances at critically high temperatures: a comparison between stenothermal antarctic and eurythermal temperate eelpouts (Zoarcidae)

The effect of gradually increased water temperature on the metabolism of temperate eelpout from the North Sea (Zoarces viviparus) and Antarctic eelpout (Pachycara brachycephalum) was investigated. Standard metabolic rate (SMR) was similar in cold-adapted P. brachycephalum and cold-acclimated Z. viviparus in the low temperature range. This indicates that Antarctic eelpout show no metabolic cold adaptation (as originally defined by Wohlschlag); however, they do show a compensatory increase of oxygen consumption compared to warm-acclimated eelpout. SMR increased more strongly with rising temperature in P. brachycephalum than in Z. viviparus, which is reflected in a higher Arrhenius activation energy for oxygen consumption (99+/-5 kJ mol(-)(1), versus 55+/-3 kJ mol(-)(1) for cold-acclimated Z. viviparus; means +/- s.d.). The intracellular pH in the white musculature of Z. viviparus follows alphastat regulation over the whole investigated temperature range and dropped at a rate of -0.016 pH units per degrees C between 3 degrees C and 24 degrees C. In Antarctic eelpout white muscle pH declined at a rate of -0.015 pH units per degrees C between 0 degrees C and 3 degrees C, but deviated from alphastat at higher temperatures, indicating that thermal stress leads to acid-base disturbances in this species. The upper critical temperature limit (Tc(II); characterised by a transition to anaerobic metabolism) was found to be between 21 degrees C and 24 degrees C for Z. viviparus and around 9 degrees C for P. brachycephalum. In both species a rise of succinate concentration in the liver tissue turned out to be the most useful indicator of Tc(II). Obviously, liver is more sensitive to heat stress than is white muscle. Accordingly, the energy status of white muscle is not diminished at Tc(II). Heat-induced hyperglycaemia was observed in Antarctic eelpout (at 9 degrees C and 10 degrees C), but not in common eelpout. Based on our results and on literature data, impaired respiration in combination with circulatory failure is suggested as the final cause of heat death. Our data suggest that the southern distribution limit of Zoarces viviparus is correlated with the limit of thermal tolerance. Therefore, it can be anticipated that global warming would cause a shift in the distribution of this species.

Journal Article↗

PubMed2003

A kinetic microplate method for quantifying the antibacterial properties of biological fluids.

The microplate assay for measuring antibacterial activity was adapted by incorporating a known concentration range of gentamicin as an internal standard. Staphylococcus aureus subsp. aureus strain ATCC 6538P, Escherichia coli ATCC 25922, and Lactobacillus spp. were used as target organisms, although other indicator organisms and antibiotics can be examined. Assay range and sensitivity were dependent on the species and density of indicator organism, and conditions (e.g., type, concentration, and pH of growth medium). Plotting the area under the growth curve (AUGC) versus gentamicin concentration (log transformed) yielded a linear curve that was used to quantify in units of gentamicin the antibacterial activity of a secretory fluid (SCF; pancreatic juice) and for comparisons of samples collected at different times, analysed on different days, and from different studies. This adaptation of the microtiter broth method will be useful for investigating man-made compounds, and the antibacterial activity of secretory fluids and the influences of age, diet, and health status.

Animals↗

PubMed2025

Tales of a Super Butterfly: Is Vanessa carye a Truly Migrant Species? Unraveling Migration Using Morphological and Genomics Approaches.

Among movement strategies, migratory behavior is particularly intriguing in insects. Home-breeding is often permanent, and return journeys can take several generations. Although migration is crucial to the ecological and evolutionary processes of the species involved, knowledge of insect migratory behavior needs to be better understood. Vanessa carye, a butterfly native to South America with a latitudinal range of ∼7,000 km, exemplifies this problem. This study analyzed samples collected across the species' range using single-nucleotide polymorphisms (SNPs) to assess population structure, genetic diversity, and geometric morphometrics to examine wing shape variation. Results indicate that V. carye forms a genetically homogeneous unit composed of only two potential populations spanning ∼5,000 km, geographically correlated with the Pacific Ocean and the Andes, maintaining constant gene flow, and with a mean heterozygosity of 5.74% (SE: ±0.048%). Geometric morphometrics detected no geographic differentiation in wing shapes and sizes across ∼7,000 km, suggesting an absence of local adaptation and indicating a conserved wing shape adapted to flight throughout the species' range. Our findings support V. carye as a migratory species with the longest migratory journey among American butterflies, revealing two migratory routes. With these approaches, we provide a consistent methodological framework for migratory studies in species with important gaps in knowledge of their natural history.

Animals↗

PubMed1989

Metabolism of isolated fish gill cells: contribution of epithelial chloride cells.

Gill cell suspensions from freshwater (FW)- and seawater (SW)-adapted teleosts were obtained by density gradient centrifugation. The proportion of chloride cells (CCs) in the mixed cell suspensions was estimated using the fluorescent mitochondrial stain, DASPMEI, and ranged from less than 1% (FW-adapted tilapia) to approximately 13% (SW-adapted toadfish). The gill cells displayed relatively high viability based on Trypan Blue exclusion (greater than 75%), lactate dehydrogenase leakage (less than 6.5% h-1), oxygen consumption rates (5-15 mumol g-1 cell wet mass h-1) and ATP levels (1-3 mumol g-1 cell wet mass). There were no obvious differences between the viability of CCs and the other cell types present. An initial comparison of gill oxidative metabolism in SW-adapted tilapia (Oreochromis mossambicus) and toadfish (Opsanus beta) demonstrated that both species oxidized glucose and lactate at substantially greater rates than alanine or oleate. Metabolic rates were significantly higher in toadfish cell suspensions. Kinetic experiments revealed that toadfish gill cells displayed lower values of Km and higher values of Vm for both lactate and glucose, in comparison to tilapia. The elevated metabolism in toadfish gill cells was correlated with increased activities of the oxidative enzyme citrate synthase and Na+/K+-ATPase. The toadfish cell suspensions had a greater proportion of CCs and it is likely that the difference in CC numbers between the two species is the basis for the observed differences in enzyme activities and rates of oxidative metabolism. This idea is supported by the highly significant correlation between Na+/K+-ATPase activity (or CC numbers) and rates of lactate oxidation in gill cell suspensions from FW- and SW-adapted tilapia and toadfish, as well as SW-adapted tilapia chronically treated with cortisol to elevate CC numbers. Although it has been assumed widely that the high metabolic rate of gill tissue reflects, in part, the oxidative demands of the chloride cell, the results of this study provide the first experimental, albeit indirect, evidence for differential rates of metabolism in the various cell types that comprise the gill.

Alanine↗

PubMed2006

Cold stress tolerance of Listeria monocytogenes: A review of molecular adaptive mechanisms and food safety implications.

The foodborne pathogen Listeria monocytogenes has many physiological adaptations that enable survival under a wide range of environmental conditions. The microbes overcome various types of stress, including the cold stress associated with low temperatures in food-production and storage environments. Cold stress adaptation mechanisms are therefore an important attribute of L. monocytogenes, enabling these food pathogens to survive and proliferate to reach minimal infectious levels on refrigerated foods. This phenomenon is a function of many molecular adaptation mechanisms. Therefore, an improved understanding of how cold stress is sensed and adaptation measures implemented by L. monocytogenes may facilitate the development of better ways of controlling these pathogens in food and related environments. Research over the past few years has highlighted some of the molecular aspects of cellular mechanisms behind cold stress adaptation in L. monocytogenes. This review provides an overview of the molecular and physiological constraints of cold stress and discusses the various cellular cold stress response mechanisms in L. monocytogenes, as well as their implications for food safety.

Adaptation, Physiological↗

PubMed2005

Endocytosis-dependent desensitization and protein synthesis-dependent resensitization in retinal growth cone adaptation.

It has been proposed that growth cones navigating through gradients adapt to baseline concentrations of guidance cues. This adaptation process is poorly understood. Using the collapse assay, we show that adaptation in Xenopus laevis retinal growth cones to the guidance cues Sema3A or netrin-1 involves two processes: a fast, ligand-specific desensitization that occurs within 2 min of exposure and is dependent on endocytosis, and a slower, ligand-specific resensitization, which occurs within 5 min and is dependent upon protein synthesis. These two phases of adaptation allow retinal axons to adjust their range of sensitivity to specific guidance cues.

Adaptation, Biological↗

PubMed1985

Myoglobin levels and mATPase activity in pectoral muscles of spruce and ruffed grouse (Aves: Tetraoninae).

Myoglobin concentration and myosin ATPase activity were measured in the pectoral muscle of wild spruce grouse (Dendragapus canadensis) and ruffed grouse (Bonasa umbellus), together with the weight of the Mm. pectoralis, supracoracoideus and heart. mATPase activities were similar in both species, but spruce grouse contained 15 times more myoglobin in the pectoralis muscle and the heart was three times heavier than that of the ruffed grouse. The relative mass of the flight muscles and wing loading were similar between species. Characteristics of the pectoral muscle of both grouse species reflect adaptations to predation and advertising displays. The glycolytic nature of the ruffed grouse pectoral muscle and small heart size is an adaptation to a sedentary existence within a small home range. The more oxidative pectoral muscle of spruce grouse together with its larger heart are adaptations to seasonal dispersals requiring more sustained flight.

Adenosine Triphosphatases↗

PubMed2003

New diagnostic potentialities of cardiorespiratory synchronization in children.

The study demonstrated that the method of cardiorespiratory synchronization provides valuable information on the nature of arrhythmia and helps to evaluate the regulatory adaptive potentialities of a child. The width of synchronization range and the latency of synchronization at the lower boundary are the indicators of regulatory adaptive potentialities.

Adaptation, Physiological↗

PubMed1988

Prevention of hip and knee injuries in ballet dancers.

Hip problems form about 10% (7.0 to 14.2%) of most published series of ballet injuries. The abnormally large range of external rotation needed for a perfect turnout is primarily due to soft tissue adaptation, more readily achieved in the young dancer. Insufficient range of motion at the hip throws considerable stress on the other lower limb segments. The snapping hip syndrome is common (43.8% of hip problems), with about one-third associated with pain. A tight iliotibial band may contribute to this, and balanced flexibility requires special attention to abductor stretching. The external clicking hip must be distinguished from the internal clicking hip, which is associated with the joint and psoas tendon. Stress fractures of the hip are easily overlooked and, if undetected, they may progress to a complete fracture. Knee problems account for 14.0 to 20% of complaints, and over 50% of these are peri- or retropatellar problems. This includes synovial plica, medial chondromalacia, lateral patella facet syndrome, subluxing patella and the fat pad syndrome. Specific diagnosis leads to specific treatment and the best chance of cure. Mild hyperextension of the knee may be aesthetically desirable, but excessive range leads to symptoms in the posterior capsule and poor control. Young dancers with a tendency to very lax joint structures should be identified early and protected from overstretching. In the author's series, meniscal lesions did not appear to be as big a problem as reported elsewhere in the literature. Ballerinas appear to have less leg strength than other groups of athletes, having only 77% of the weight-predicted norms. The introduction of strength training for male and female dancers may reduce injuries and improve balance, but it requires an intensive educational programme to dispense with the many myths. There are several references to the development of early arthritis but, while relatively common in the foot, symptomatic arthrosis in ballet dancers' hips and knees is not more prevalent than in the general population. The young age at which serious dance training begins, the long and rigorous hours of practice, the thin ballet slipper, dancing en pointe and unusual dietary regimens may all contribute to injury patterns in varying degrees.

Dancing↗

PubMed1992

Spatial-frequency-contingent color aftereffects: adaptation with one-dimensional stimuli.

The McCollough effect was shown to be spatial-frequency selective by Lovegrove and Over (1972) after adaptation with vertical colored square-wave gratings separated by 1 octave. Adaptation with slide-presented red and green vertical square-wave gratings separated by 1 octave failed to produce contingent color aftereffects (CAEs). However, when each of these gratings was adapted alone, strong CAEs were produced. Adaptation with vertical colored sine-wave gratings separated by 1 octave also failed to produce CAEs, but strong effects were produced by adaptation with each grating alone. By varying the spatial frequency of the test sine wave, CAEs were found to be tuned for spatial frequency at 2.85 octaves after adaptation of 4 cycles per degree (cpd) and at 2.30 octaves after adaptation of 8 cpd. Adaptation of both vertical and horizontal sine-wave gratings produced strong CAEs, with bandwidths ranging from 1.96 to 2.90 octaves and with lower adapting contrast producing weaker CAEs. These results indicate that the McCollough effect is more broadly tuned for spatial frequency than are simple adaptation effects.

Adaptation, Ocular↗

PubMed2001

Axial strain imaging of intravascular data: results on polyvinyl alcohol cryogel phantoms and carotid artery.

Mapping the local elastic properties of an atherosclerotic artery is of major interest for predicting the disease evolution or an intervention outcome. These properties can be investigated by elastography, which estimates the strain distribution within a medium in response to a stress. But because diseased arteries are highly heterogeneous, a small global deformation may result in high local strains in the softest regions. For those reasons, we use in this paper the strain estimation method we recently developed to compute elastograms of original vessel-mimicking cryogel phantoms and a fresh excised human carotid artery. This adaptive method has been effectively proved to be accurate in a wider range of strains (0-7%) than commonly used gradient-based methods, and very adapted for investigating highly heterogeneous tissues. Resulting elastograms cover a wider range of strains (0-3.5%) than all previously reported intravascular elastograms, improving the discrimination between healthy and diseased regions.

Carotid Artery Diseases↗

PubMed2002

The Trauma Recovery and Empowerment Model (TREM): conceptual and practical issues in a group intervention for women.

This article describes the Trauma Recovery and Empowerment Model (TREM), a manualized group intervention designed for women trauma survivors with severe mental disorders, and discusses key issues in its conceptualization and implementation. TREM recognizes the complexity of long-term adaptation to trauma and addresses a range of difficulties common among survivors of sexual and physical abuse. Focusing primarily on the development of specific recovery skills and current functioning, TREM utilizes techniques shown to be effective in trauma recovery services. The group's content and structure are also informed by the role of gender in the ways women experience and cope with trauma.

Adaptation, Psychological↗