Variation In Physiological Responses Research Articles

Resistance to oxidative damage but not immunosuppression by organic tin compounds in natural populations of Daubenton's bats (Myotis daubentonii)

The acute toxicity of organic tin compounds (OTCs) has been studied in detail. However, due to their complex nature, very little is known about species-specific methods of accumulation and consequences for food-webs. Chironomids, on which e.g. Daubenton's bats feed, may act as vectors for the transport of organic tin compounds from aquatic to terrestrial ecosystems. Bats are prone to environmental toxins because of their longevity and their ecological role as top predators. Organic tin compounds are associated with increased formation of reactive oxygen species and associated oxidative damage as well as suppression of immune function. The present paper investigates whether the OTC, tributyltin (TBT) and its metabolite, dibutyltin (DBT), accumulate in natural populations of Daubenton's bats and whether TBT-associated effects are seen in general body condition, redox balance, redox enzyme activities, associated oxidative damage of red blood cells and complement function. We discovered the concentration of bat fur DBT correlated with local marine sediment TBT concentrations. However, we did not find a correlation between the explanatory factors, bat fur DBT and marine sediment TBT concentrations, and several physiological and physical response variables apart from complement activity. Higher DBT concentrations resulted in weaker complement activity and thus a weaker immune response. Although the observed physiological effects in the present study were not strongly correlated to butyltin concentrations in fur or sediment, the result is unique for natural populations so far and raises interesting questions for future ecotoxicological studies.

Does season or captivity influence the physiology of an endangered marsupial, the numbat (Myrmecobius fasciatus)?

We examined the effects of season and captivity on several commonly measured physiological variables (body temperature, metabolic rate, thermal conductance, and evaporative water loss [EWL]) for the numbat (Myrmecobius fasciatus), an endangered myrmecophagous Australian marsupial, because the maintenance of a wild-type physiology may increase the likelihood of successful reintroduction of numbats into the wild. Our results indicate that the physiology of male captive numbats is representative of wild individuals, at least at thermoneutrality, except for some diet-related effects on substrate metabolism and thermoregulation. Season significantly influenced physiological variables, in particular basal metabolic rate (BMR) and EWL. BMR was 30–37% higher in winter than in summer, and EWL increased at a high ambient temperature (Ta) in winter, presumably reflecting seasonal differences in Ta, food availability, and water consumption. Seasonal variation in physiological responses of captive numbats was similar to that observed for wild numbats. We conclude that there is seasonal flexibility in the physiology of numbats, and that captivity under seminatural conditions does not compromise their basic physiology.

No Differences in O2-Cost between V1 and V2 Skating Techniques During Treadmill Roller Skiing at Moderate to Steep Inclines

Elite crosscountry skiers use both the V1 and V2 techniques on moderate and steep inclines despite previous studies suggesting that the V1 technique is superior in terms of lower O2-cost and better performance on these inclines. However, this has not been studied in elite athletes, and therefore, the aim of this study was to compare O2-cost in these 2 main ski skating techniques in a group of 14 elite male crosscountry skiers (age: 24 ± 3 years, height: 184 ± 6 cm, weight: 79 ± 7 kg, V1 V[Combining Dot Above]O2max: 71.8 ± 3.5 ml·kg·min). With both techniques, the athletes performed submaximal trials for the determination of O2-cost on a roller ski treadmill at 4, 5, and 6° (3 m·s) and maximal trials at 8° (≥3 m·s) for the determination of V[Combining Dot Above]O2max. Video-based kinematic analyses on cycle length and cycle rate (CR) were performed to unravel if there was any relation between these variables and O2-cost. No significant differences in O2-cost or V[Combining Dot Above]O2max between techniques were found. However, large and significant individual variations in physiological response were observed. V2 had a longer cycle length and lower CR than V1 did. No significant correlation was found between CR and O2-cost. This study shows that both V1 and V2 are appropriate techniques for optimizing O2-cost on moderate to steep inclines in elite skiers. However, individual variation suggests that ski skating performance on moderate to steep inclines may be determined by technique preferences of the athletes.

Circadian changes in heat storage and heat loss through sweating and panting in Karan Fries cattle during different seasons

In order to find out the circadian variations in physiological responses, heat storage and heat loss, experiment was conducted on 12 female Karan Fries (KF) cattle selected from National Dairy Research Institute (NDRI) herd. Animals were further divided equally in two groups namely growing (8–12 months) and adults (18–24 months), and experiment was conducted during winter (December to January), spring (February to March) and summer (April to May) seasons. Physiological responses (respiration rate (RR), rectal temperature (RT), skin temperature (ST) and pulse rate (PR)), heat storage and heat loss through evaporation from skin (sweating) and pulmonary system (panting), dry bulb temperature (DBT) and wet bulb temperature (WBT), relative humidity, minimum and maximum temperatures, wind speed and temperature humidity index were calculated at 4-h intervals round the clock. Physiological responses (RR, RT, ST and PR) increased significantly (p < 0.01) during spring and summer season. RR and PR were positively correlated with DBT. The circadian rhythmic variations in core temperatures during summer season were 1.0°C and 1.4°C, respectively, for adult and growing KF cattle. Heat loss through skin and pulmonary system was maximum in adult (76.8% and 23.2%) during summer at 2 pm compared to growing (73.9% and 26.1%). Heat storage was found to be maximum in adult than growing during all seasons. Heat storage increases as the intensity of solar radiation increases, and also higher is the surface area higher is the heat storage. Therefore, the experiment was conducted to study the influence of heat stress during the different periods in crossbred cattle.

Tracing the Variation in Physiological Response to Rifampicin Across the Microbial Spectrum

Rifampicin is an acknowledged inhibitor of bacterial RNA polymerase. We observed that there exists a substantial variation in the basal-level tolerance to rifampicin across microbial species. A number of mechanisms have come to light which depict the molecular aspects of the behavior of an individual bacterial cell towards rifampicin. This review assesses the current knowledge about rifampicin and conjectures about the probable aspects of rifampicin which remain unexplored.

Differential effect of wave stress on the physiology and behaviour of native versus non-native benthic invertebrates

In fresh waters, non-native invertebrate species preferentially spread via navigation waterways, where they often dominate assemblages. Littoral habitats in navigation waterways are regularly exposed to ship-induced waves. We conducted experiments to test the effects of artificial wave exposure on the relative performance of wide-spread native and non-native species. We compared physiological and behavioural response variables (i.e. growth rate, glycogen content, feeding and swimming activity) of two amphipods (native Gammarus roeselii and non-native Dikerogammarus villosus) and two gastropods (native Bithynia tentaculata and non-native Physella acuta) subject to wave and control (i.e. no wave) treatment flumes across a 6-week period. Growth, and in part glycogen content (as a measure of energy storage), were significantly reduced after exposure to waves in native invertebrates, but not in non-native invertebrates. The reduction in growth may be associated with the disturbance effects of waves, such as the higher swimming activity of G. roeselii and lower food uptake of B. tentaculata. In comparison, the effective hiding behaviour observed for D. villosus and good swimming ability of P. acuta, were identified as important traits facilitating the successful colonisation of the harsh habitat conditions of littoral waterways. Our study demonstrates that artificial wave regimes may contribute significant selective pressure, thus explaining the observed dominance of non-native species in navigational waterways. The success of non-native species under the harsh hydraulic habitat conditions of these socio-economically driven ecosystems may consequently be traced directly to behavioural and/or physiological traits.

The effect of shearing in a hot environment on some welfare indicators in Awassi lambs

The aim of this study was to analyze the effects of shearing on the individual behaviors and rectal temperature profile during the day at hot environment in Awassi lambs. Twenty Awassi male lambs were randomly allocated into shorn (n = 10) and unshorn (n = 10) groups (28.8 ± 0.7 and 29.9 ± 0.7kg, respectively) and were kept indoor during the experiment. The physiological and behavioral response variables measured were rectal temperature, standing, lying, feeding, ruminating, drinking, locomotor activity, and elimination. The effect of day, time of day, and all interactions on rectal temperature were found significant (P < 0.001). The effect of shearing on the rectal temperatures of lambs was tend to be significant (P = 0.06). Overall, unshorn lambs showed more frequencies of locomotor activity (P < 0.05) and there was a tendency of less standing behavior (P = 0.08) when compared to the lambs in shorn group. The difference of the other behaviors was not significant (P > 0.05). Within the observation hours, there was a tendency of difference for behavioral frequencies between groups especially early in the day and late at night (P = 0.07). But during the day, the difference of behavior type between groups was highly significant at 1300 and 1600hours (P < 0.01 and P < 0.001, respectively). The findings of the current study showed that the behavior of shorn lambs changed with the changing of environmental heat and showed more behavioral differences at 1300hours but they tend to cope with heat stress better than unshorn lambs in a hot environment when their rectal temperatures were compared.

Circadian changes in physiological responses and blood ionized sodium and potassium concentrations under thermal exposure in Tharparkar and Karan Fries heifers

To explore the circadian changes in physiological responses and blood ionized sodium, potassium concentrations under thermal exposure in Tharparkar (TP) and Karan Fries (KF) heifers, 12 animals, six each from two breeds were taken and kept first in control thermoneutral (21–26°C and 50–60% RH) and in heat exposed (38°C and 50–60% RH) conditions thereafter. Throughout a 24-hour period physiological responses (rectal temperature, respiration rate and pulse rate) and blood samples were taken at 4-hour intervals, then blood samples were analyzed for sodium (Na+) and potassium (K+) levels. Significant circadian variations in physiological responses and blood Na+ and K+ within 24 hours have been observed. Significant (P < 0.01) variation in physiological responses and blood Na+, K+ concentrations were observed in both Tharparkar and Karan Fries heifers under control and heat exposed conditions. Values of physiological responses were lower in the morning and showed an increasing trend and reached the highest value in the afternoon. Blood Na+ and K+ concentrations decreased from 11.00 hours to 19.00 hours due to heat exposure. The decreases in blood electrolyte levels were greater in Karan Fries in comparison to Tharparkar heifers that expressed less heat tolerance capacity in crossbred than indigenous cattle. This finding suggests that it is important to standardize the time of sample collection in comparative studies, in which more discrete differences may be identified in physiological responses and blood electrolyte concentrations.

Automated real-time behavioral and physiological data acquisition and display integrated with stimulus presentation for fMRI

Functional magnetic resonance imaging (fMRI) is based on correlating blood oxygen-level dependent (BOLD) signal fluctuations in the brain with other time-varying signals. Although the most common reference for correlation is the timing of a behavioral task performed during the scan, many other behavioral and physiological variables can also influence fMRI signals. Variations in cardiac and respiratory functions in particular are known to contribute significant BOLD signal fluctuations. Variables such as skin conduction, eye movements, and other measures that may be relevant to task performance can also be correlated with BOLD signals and can therefore be used in image analysis to differentiate multiple components in complex brain activity signals. Combining real-time recording and data management of multiple behavioral and physiological signals in a way that can be routinely used with any task stimulus paradigm is a non-trivial software design problem. Here we discuss software methods that allow users control of paradigm-specific audio–visual or other task stimuli combined with automated simultaneous recording of multi-channel behavioral and physiological response variables, all synchronized with sub-millisecond temporal accuracy. We also discuss the implementation and importance of real-time display feedback to ensure data quality of all recorded variables. Finally, we discuss standards and formats for storage of temporal covariate data and its integration into fMRI image analysis. These neuroinformatics methods have been adopted for behavioral task control at all sites in the Functional Biomedical Informatics Research Network (FBIRN) multi-center fMRI study.

Response to environmental change in rainbow trout selected for divergent stress coping styles

An extensive literature has documented differences in the way individual animals cope with environmental challenges and stressors. Two broad patterns of individual variability in behavioural and physiological stress responses are described as the proactive and reactive stress coping styles. In addition to variability in the stress response, contrasting coping styles may encompass a general difference in behavioural flexibility as opposed to routine formation in response to more subtle environmental changes and non-threatening novelties. In the present study two different manipulations, relocating food from a previously learned location, and introducing a novel object yielded contrasting responses in rainbow trout selected for high (HR) and low (LR) post stress plasma cortisol levels. No difference was seen in the rate of learning the original food location; however, proactive LR fish were markedly slower than reactive HR fish in altering their food seeking behaviour in response to relocated food. In contrast, LR fish largely ignored a novel object which disrupted feeding in HR fish. Hence, it appears that the two lines appraise environmental cues differently. This observation suggests that differences in responsiveness to environmental change are an integral component of heritable stress coping styles, which in this particular case, had opposite effects on foraging efficiency in different situations. Context dependent fitness effects may thus explain the persistence of stable divergence of this evolutionary widespread trait complex.

An examination of repeatability in physiological responses to simulated low amplitude sonic booms of various peak levels and rise times.

Findings from recent low-level sonic boom studies have shown that people’s evaluations of startle could not be explained by loudness only and the startle evaluations were correlated strongly with evaluations of annoyance. A pilot study was conducted to examine how changes in physiological responses (skin conductance, pulse rate, and EMG) compared with subjective ratings startle. Analysis of this data was difficult because the intervals between stimuli were not long enough for some of the physiological measures to return to baseline before the next stimulus exposure. In addition, repeatability of responses was difficult to measure because of the complexity of the test which involved the subject doing several tasks while being exposed to the sounds. To examine what level of physiological response repeatability can be expected in these sonic boom experiments, another test was conducted in which subjects were exposed to simulated sonic booms. The interval required between boom exposures necessary to return to baseline was also examined. To examine the day-to-day repeatability of these measures, each subject completed several sessions on separate days. The variations in physiological responses within and between subjects will be described along with the trends observed related to signal characteristics.

Effect of the pre-slaughter logistic chain on some indicators of welfare in lambs

The present study analyzed the effects of the pre-slaughter logistic chain on some indicators of welfare and meat quality in commercial light lambs at two different seasons. A total of 144 male lambs of the Rasa Aragonesa breed were sampled in a 3 × 2 factorial design, testing three different stay times at a classification centre (CC). The CC had a central barn for weight classification with a curved race system and scale. Lambs at (or at times over) the correct commercial weight were kept in holding pens in the central barn. Lambs below commercial weight were sent to fattening pens in two large lateral barns (with 50 pens of approximately 18 m 2 each for about 40). The groups were classified as G0 (only a few hours at the CC), G7 (7 days of fattening at the CC) and G28 (28 days of fattening at the CC). Two replicates were performed per treatment and two replicates were carried out in the different seasons (summer and winter). The approximate age and weights of the lambs were 100 days and 28.3 ± 0.25 kg (G0), 93 days and 25.5 ± 0.25 kg (G7), 72 days and 17.3 ± 0.25 kg (G28). The physiological stress response variables measured were cortisol, lactate, glucose, creatinine kinase (CK), non-esterified fatty acid (NEFA), white blood cells (WBC), red blood cells (RBC), haematocrit and ratio of neutrophil:lymphocytes (N/L). The ultimate pH on Longissimus dorsi (pH24) and bruising score of the carcass were assessed. Stay time and season had a significant effect on stress variables. Cortisol and lactate levels were highest for G28 ( p < 0.01) while haematocrit was highest for G0 ( p < 0.05). The G0 and G7 lambs had higher levels of glucose than G28 ( p < 0.05). The highest WBC count was observed for G28 ( p < 0.001). In winter, cortisol and glucose levels were higher, while in summer CK was highest ( p ≤ 0.001). In summer, N/L was significantly higher in G28 ( p ≤ 0.001). Cold temperatures had a significant effect on pH24 and bruising score ( p ≤ 0.001). The results of our study suggest that the pre-slaughter logistic chain was a source of stress for the lambs, affecting their physiological state, even under optimal commercial conditions. This effect may represent the cumulative effects of all factors associated with the classification centre.

Within- and Between-Day Repeatability and Variability in Children's Physiological Responses During Submaximal Treadmill Exercise

The purpose of this study was to verify within- and between-day repeatability and variability in children's oxygen uptake (VO^sub 2^), gross economy (GE; VO^sub 2^ divided by speed) and heart rate (HR) during treadmill walking based on self-selected speed (SS). Fourteen children (10.1 ± 1.4 years) undertook three testing sessions over 2 days in which four walking speeds, including SS were tested. Within- and between-day repeatability were assessed using the Bland and Altman method, and coefficients of variability (CV) were determined for each child across exercise bouts and averaged to obtain a mean group CV value for VO^sub 2^, GE, and HR per speed. Repeated measures analysis of variance showed no statistically significant differences in within- or between-day CV for VO^sub 2^, GE, or HR at any speed. Repeatability within- and between-day for VO^sub 2^, GE, and HR for all speeds was verified. These results suggest that submaximal VO^sub 2^ during treadmill walking is stable and reproducible at a range of speeds based on children's SS.

Within- and Between-Day Repeatability and Variability in Children's Physiological Responses During Submaximal Treadmill Exercise

The purpose of this study was to verify within- and between-day repeatability and variability in children's oxygen uptake (VO2), gross economy (GE; VO2 divided by speed) and heart rate (HR) during treadmill walking based on self-selected speed (SS). Fourteen children (10.1 ± 1.4 years) undertook three testing sessions over 2 days in which four walking speeds, including SS were tested. Within- and between-day repeatability were assessed using the Bland and Altman method, and coefficients of variability (CV) were determined for each child across exercise bouts and averaged to obtain a mean group CV value for VO2, GE, and HR per speed. Repeated measures analysis of variance showed no statistically significant differences in within- or between-day CV for VO2, GE, or HR at any speed. Repeatability within- and between-day for VO2, GE, and HR for all speeds was verified. These results suggest that submaximal VO2 during treadmill walking is stable and reproducible at a range of speeds based on children's SS.

Athletic Performance and the Oral Contraceptive

Some reports suggest variation in physiological responses and athletic performance, for female athletes at specific phases of the menstrual cycle. However, inconsistent findings are common due to the inappropriate verification of menstrual cycle phase, small subject numbers, high intra- and interindividual variability in estrogen and progesterone concentration, and the pulsatile secretion of these hormones. Therefore, the oral contraceptive (OC) cycle may provide a more stable environment in which to evaluate the acute effect of reproductive hormones on physiological variables and exercise performance. To date, most of the OC research has compared differences between OC use and nonuse, and few researchers have examined within-cycle effects of the OC. It is also apparent that OC use is becoming far more prevalent in athletes; hence the effect of the different exogenous and endogenous hormonal profiles on athletic performance should be investigated. Research to date identifies potential for variation in aerobic performance, anaerobic capacity, anaerobic power and reactive strength throughout an OC cycle. The purpose of this review is to present and evaluate the current literature on the physiology of exercise and athletic performance during the OC cycle.

Learning from children: the emergence of pediatric exercise science

which unique insights can be gained from the investigations of the physiology of the growing child? Are there pragmatic outcomes to research in children's exercise science that bear specific utility to this age group or to their future life? What importance do exercise responses in youth bear to our

Geographical variation in the response to nitrogen deposition inArabidopsis lyrata petraea

The adaptive responses to atmospheric nitrogen deposition for different European accessions of Arabidopsis lyrata petraea were analysed using populations along a strong atmospheric N-deposition gradient. Plants were exposed to three N-deposition rates, reflecting the rates at the different locations, in a full factorial design. Differences between accessions in the response to N were found for important phenological and physiological response variables. For example, plants from low-deposition areas had higher nitrogen-use efficiencies (NUE) and C : N ratios than plants from areas high in N deposition when grown at low N-deposition rates. The NUE decreased in all accessions at higher experimental deposition rates. However, plants from high-deposition areas showed a limited capacity to increase their NUE at lower experimental deposition rates. Plants from low-deposition areas had faster growth rates, higher leaf turnover rates and shorter times to flowering, and showed a greater increase in growth rate in response to N deposition than those from high-deposition areas. Indications for adaptation to N deposition were found, and results suggest that adaptation of plants from areas high in N deposition to increased N deposition has resulted in the loss of plasticity.

Signal strength and climate calibration of a European tree‐ring isotope network

We present the first European network of tree ring δ13C and δ18O, containing 23 sites from Finland to Morocco. Common climate signals are found over broad climatic‐ecological ranges. In temperate regions we find positive correlations with summer maximum temperatures and negative correlations with summer precipitation and Palmer Drought Severity Indices (PDSI) with no obvious species‐specific differences. Regional δ13C and δ18O chronologies share high common variance in year‐to‐year variations. Long‐term variations, however, exhibit differences that may reflect spatial variability in environmental forcings, age trends and/or plant physiological responses to increasing atmospheric CO2 concentration. Rotated principal component analysis (RPCA) and climate field correlations enable the identification of four sub‐regions in the δ18O network ‐ northern and eastern Central Europe, Scandinavia and the western Mediterranean. Regional patterns in the δ13C network are less clear and are timescale dependent. Our results indicate that future reconstruction efforts should concentrate on δ18O data in the identified European regions.

238 Variability of acute physiological responses and performance profiles of youth soccer players in small-sided games

238 Variability of acute physiological responses and performance profiles of youth soccer players in small-sided games

Effects of shoot bending on lateral fate and hydraulics: invariant and changing traits across five apple genotypes

The aim of this work was to study the variability of physiological responses to bending and the relationship with hydraulic conductance of the sap pathway to the laterals for five apple genotypes. The study focuses on the fate of the laterals. The genetic variability of bending can have two sources: a genetic variability of stem geometry which can lead to differences in mechanical state; and a genetic variability of sensitivity to bending. Since the aim was to check if some genetic variability of sensitivity to bending exists, the genetic variability of shoot geometry was taken into account. To do so, bending was controlled by imposing different bending intensities using guides of different curvature conferring a similar level of deformation to the five genotypes. Bending was done either in the proximal zone or in the distal zone of shoots, in June and in the following winter, respectively. A Principal Component Analysis comparing upright and bent shoots revealed that bending in the proximal zone stimulated vegetative growth of buds which would otherwise stay latent. A second Principal Component Analysis restricted to bent shoots revealed that bending increased the abortion of laterals in the lower face of the shoots. The abortion phenomenon was to the detriment of sylleptic laterals or of inflorescence, depending on the genotype. There was a strong effect of position around the shoot on within-shoot hydraulics. Hydraulic conductance was significantly decreased in the lower face of the shoot bent in winter. This result suggested a causal relationship between this phenomenon and lateral abortion.