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1.
Body temperature (Tb) represents one of the key parameters in ecophysiological studies with focus on energy saving strategies. In this study we therefore comparatively evaluated the usefulness of two types of temperature-sensitive passive transponders (LifeChips and IPTT-300) and one data logger (iButton, DS1922L) mounted onto a collar to measure Tb in the field. First we tested the accuracy of all three devices in a water bath with water temperature ranging from 0 to 40 °C. Second, we evaluated the usefulness of the LifeChips and the modified iButtons for measuring Tb of small heterothermic mammals under field conditions. For this work we subcutaneously implanted 14 male edible dormice (Glis glis) with transponders, and equipped another 14 males with data loggers to simultaneously record Tb and oxygen consumption with a portable oxygen analyzer (Oxbox). In one individual we recorded Tb with both devices and analyzed recorded Tb patterns.LifeChips are able to measure temperature within the smallest range from 25 to 40 °C with an accuracy of 0.07±0.12 °C. IPTT-300 transponders measured temperature between 10 and 40 °C, but accuracy decreased considerably at values below 30 °C, with maximal deviations of nearly 7 °C. An individual calibration of each transponder is therefore needed, before using it at low Tbs. The accuracy of the data logger was comparatively good (0.12±0.25 °C) and stable over the whole temperature range tested (0–40 °C). In all three devices, the repeatability of measurements was high.LifeChip transponders as well as modified iButtons measured Tb reliably under field conditions. Simultaneous Tb-recordings in one edible dormouse with an implanted LifeChip and a collar-mounted iButton revealed that values of both measurements were closely correlated. Taken together, we conclude that implanted temperature-sensitive transponders represent an appropriate and largely non-invasive method to measure Tb also under field conditions.  相似文献   

2.
Most mammals are known to have clear circadian rhythms of body temperature (Tb) and metabolic rate. Large parts of the rhythms correspond to the oscillation of nonshivering thermogenesis (NST), dependent on visceral organ mass, and, affected by mass of brown adipose tissue (BAT). I tested whether: (1) a different levels of BMR result in respective changes of Tb values and the magnitude of daily RMR oscillations both within and below thermoneutrality; (2) the amplitude of daily variation of RMR depends on ambient temperature (Ta). I studied: (1) daily variation of body temperature at Ta of 23 °C, and (2) the rate of resting metabolism (RMR) within and below thermoneutrality at the time of minimum and increasing Tb (minimum and maximum NST capacity), in two lines of laboratory mice subjected to divergent, artificial selection toward high (HBMR) and low (LBMR) basal rate of metabolism (BMR). All mice had a clear circadian rhythm of Tb with minimum of 36.4±0.2 °C at 7:00 and maximum of 37.8±0.2 °C at 21:00. Their RMR measured below thermoneutrality exhibited significant daily variation, with the maximum between 16:00 and 19:00, when Tb was rising. Within thermoneutral zone (TNZ) I found between-line, but not between-time, differences in RMR. All between-line differences in RMR could be explained by the magnitude of BMR. I did not find any between-line differences of RMR value in temperatures below thermoneutrality. The amplitude of daily variation of RMR measured below TNZ depended neither on the Ta value nor on level of BMR (or visceral organs).  相似文献   

3.
(1) The thermal capabilities of Australian silvereyes (Zosterops lateralis, 11 g) were investigated both at low and high ambient temperatures (Ta) during the photophase and scotophase. (2). The peak metabolic rate (PMR) induced by helium–oxygen (79:21 %, He–O2) exposure during the photophase was 15.64±1.55 mL O2 g−1 h−1 at an effective lower survival limit Ta (Tpmr) of −39.7±6.1°C. (3). Above the thermoneutral zone (TNZ), metabolic rate, body temperature (Tb), and thermal conductance increased steeply, but they were able to withstand a Ta of 39°C. (4). Our study shows that silvereyes are able to tolerate an impressive range of Ta from about −42°C to at least +39°C and are able to produce enough heat to maintain a thermal difference between Tb and Ta of up to 80°C.  相似文献   

4.
Hibernation in mammals involves major alterations in nutrition and metabolism that would be expected to affect levels of circulating molecules. To gain insight into these changes we conducted a non-targeted LC–MS based metabolomic analysis of plasma using hibernating ground squirrels in late torpor (LT, Tb ~ 5 °C) or during an interbout arousal period (IBA, Tb ~ 5 °C) and non-hibernating squirrels in spring (Tb ~ 37 °C). Several metabolites varied and allowed differentiation between hibernators and spring squirrels, and between torpid and euthermic squirrels. Methionine and the short-chain carnitine esters of propionate and butyryate/isobutyrate were reduced in LT compared with the euthermic groups. Pantothenic acid and several lysophosphatidylcholines were elevated in LT relative to the euthermic groups, whereas lysophosphatidylethanolamines were elevated during IBA compared to LT and spring animals. Two regulatory lipids varied among the groups: sphingosine 1-phosphate was lower in LT vs. euthermic groups, whereas cholesterol sulfate was elevated in IBA compared to spring squirrels. Levels of long-chain fatty acids (LCFA) and total NEFA tended to be elevated in hibernators relative to spring squirrels. Three long-chain acylcarnitines were reduced in LT relative to IBA; free carnitine was also lower in LT vs. IBA. Our results identified several biochemical changes not previously observed in the seasonal hibernation cycle, including some that may provide insight into the metabolic limitations of mammalian torpor.  相似文献   

5.
The aim of the investigation was to verify our hypothesis that extreme tolerance of newborn rodents to anoxia is determined by their ability to maintain reduced body temperature and to keep on gasping.Newborn Wistar rats were used. In separate experiments we checked (1) effect of extreme thermal conditions on rectal temperature (Tre) of the newborns in their nests; (2) effect of ambient temperature (Ta) on oxygen consumption; (3) effects of controlled changes in Tre on thermoregulatory and respiratory responses to anoxia and on anoxia tolerance.In their nests rat pups controlled Tre at 32–36 °C while the TreTa difference changed within a range of 1–20 °C. The lowest oxygen consumption of ∼24 ml O2 kg−1 min−1 was recorded at Ta of 32 °C. Pups, exposed to anoxia at their normal Tre of 33 °C, were able to decrease Tre by another 1.7 °C and they kept on extremely slow and quiescent gasping for scheduled 25 min. In contrast, rats at Tre of 37 °C and 39 °C reached a critical phase of accelerated and shallow gasping after 14.95±0.40 min and 9.25±0.30 min, respectively.In conclusion, reduced Tre and unique gasping ability make newborn rats extremely tolerant to asphyxia.  相似文献   

6.
The red-tailed phascogale is a small arboreal dasyurid marsupial that inhabits semi-arid to arid regions of Western Australia's wheat belt. Its body mass (34.7 g) is only ~15% of that predicted based on its phylogenetic position among other dasyuromorphs; we interpret this as an adaptation to its scansorial and semi-arid/arid lifestyle. The standard physiology of this species at a thermoneutral ambient temperature of 30 °C conforms to that of other dasyurid marsupials; body temperature (34.7 ± 0.37 °C), basal metabolic rate (0.83 ± 0.076 mL O2 g?1 h?1), evaporative water loss (1.68 ± 0.218 mg H2O g?1 h?1) and wet thermal conductance (3.8 ± 0.26 J g?1 h?1 °C?1) all fall within the 95% predication limits for the respective allometric relationships for other dasyurid species. Thermolability confers an energy savings at low Ta and water savings at high Ta. Torpor, observed at low Ta, was found to be more beneficial for energy savings than for water economy. The red-tailed phascogale therefore has a physiology suitable for the challenges of arid environments without any obvious requirement for adaptations to its scansorial lifestyle, other than its considerably lower-than-expected body mass.  相似文献   

7.
Medicinal leeches (Hirudo verbana) thermoregulate with respect to their sanguivorous feeding behavior. Immediate postprandial preferences are for warmer than their initial acclimation temperature (Ta, 21 °C, Petersen et al. 2011), while unfed leeches have a lower preferred temperature (Tpref, 12.5 °C). This may reduce energy expenditure and defer starvation if feeding opportunities are limited. Energetic benefits may have an associated cost if low temperatures reduce mobility and the ability to locate further hosts. These costs could be limited if mobility is unimpaired at low temperatures, or if acclimation can restore locomotor performance to the levels at Ta. The transition from Ta to the unfed Tpref significantly reduced speed and propulsive cycle frequency during swimming, and extension and retraction rates during crawling. Aerobic metabolic rate was also reduced from 0.20±0.03 W kg−1 at Ta to 0.10±0.03 W kg−1 at Tpref. The Q10 values of 1.7–2.9 for energetic and swimming parameters indicate a substantial temperature effect, although part of the decline in swimming performance can be attributed to temperature-related changes in water viscosity. 6 weeks at Ta resulted in no detectable acclimation in locomotor performance or aerobic metabolism. The energetic savings associated with a lower Tpref in unfed leeches effectively doubled the estimated time until depletion of energy reserves. Given that some mobility is still retained at Tpref, and that acclimation is in itself costly, the energetic benefits of selecting cooler temperatures between feedings may outweigh the costs associated with reduced locomotor performance.  相似文献   

8.
Global warming is occurring at an alarming rate and predictions are that air temperature (Ta) will continue to increase during this century. Increases in Ta as a result of unabated production of greenhouse gases in our atmosphere pose a threat to the distribution and abundance of wildlife populations worldwide. Although all the animals worldwide will likely be affected by global warming, diurnal animals in the deserts will be particularly threatened in the future because Tas are already high, and animals have limited access to water. It is expected that Saudi Arabia will experience a 3–5 °C in Ta over the next century. For predicting the consequences of global warming for animals, it is important to understand how individual species will respond to higher air temperatures. We think that populations will not have sufficient time to make evolutionary adjustments to higher Ta, and therefore they will be forced to alter their distribution patterns, or make phenotypic adjustments in their ability to cope with high Ta. This report examines how increases in Ta might affect body temperature (Tb) in the animals of arid regions. We chose three taxonomic groups, mammals, birds, and reptiles (Arabian oryx, Arabian spiny-tailed lizard, vultures, and hoopoe larks) from Saudi Arabia, an area in which Ta often reaches 45 °C during midday in summer. When Ta exceeds Tb, animals must resort to behavioral and physiological methods to control their Tb; failure to do so results in death. The observations of this study show that in many cases Tb is already close to the upper lethal limit of around 47° C in these species and therefore allowing their Tb to increase as Ta increases are not an option. We conclude that global warming will have a detrimental impact on a wide range of desert animals, but in reality we know little about the ability of most animals to cope with change in Ta. The data presented should serve as base-line information on Tb of animals in the Kingdom for future scientists in Saudi Arabia as they explore the impact of global warming on animal species.  相似文献   

9.
It has been speculated that the control of core temperature is modulated by physiological demands. We could not prove the modulation because we did not have a good method to evaluate the control. In the present study, the control of core temperature in mice was assessed by exposing them to various ambient temperatures (Ta), and the influence of circadian rhythm and feeding condition was evaluated. Male ICR mice (n=20) were placed in a box where Ta was increased or decreased from 27 °C to 40 °C or to −4 °C (0.15 °C/min) at 0800 and 2000 (daytime and nighttime, respectively). Intra-abdominal temperature (Tcore) was monitored by telemetry. The relationship between Tcore and Ta was assessed. The range of Ta where Tcore was relatively stable (range of normothermia, RNT) and Tcore corresponding to the RNT median (regulated Tcore) were estimated by model analysis. In fed mice, the regression slope within the RNT was smaller in the nighttime than in the daytime (0.02 and 0.06, respectively), and the regulated Tcore was higher in the nighttime than in the daytime (37.5 °C and 36.0 °C, respectively). In the fasted mice, the slope remained unchanged, and the regulated Tcore decreased in the nighttime (0.05 and 35.9 °C, respectively), while the slopes in the daytime became greater (0.13). Without the estimating individual thermoregulatory response such as metabolic heat production and skin vasodilation, the analysis of the TaTcore relationship could describe the character of the core temperature control. The present results show that the character of the system changes depending on time of day and feeding conditions.  相似文献   

10.
The influence of reaction media on the racemic temperature (Tr) in the lipase-catalyzed resolution of ketoprofen vinyl ester was investigated. An effective approach to the control of the enzymatic enantioselectivity and the prediction of the increasing tendency was developed based on the Tr influenced by reaction media. The Tr for the resolution catalyzed by Candida rugosa lipase (CRL) was found at 29 °C in aqueous and S-ketoprofen was obtained predominantly at 40 °C. However, CRL showed R-selectivity at 40 °C in diisopropyl ether because the Tr was changed to 56 °C. CRL, lipase from AYS Amano® and Mucor javanicus lipase were further applied for the investigation of the enzymatic enantioselectivity in dioxane, DIPE, isooctane and their mixed media with water. The effects of the reaction medium on Tr could be related to the solvent hydrophobicity, the lipase conformational flexibility and the interaction between the enantiomers and the lipase.  相似文献   

11.
Extreme environmental conditions present challenges for thermoregulation in homoeothermic organisms such as mammals. Such challenges are exacerbated when two stressors are experienced simultaneously and each stimulus evokes opposing physiological responses. This is the case of cold, which induces an increase in thermogenesis, and hypoxia, which suppresses metabolism conserving oxygen and preventing hypoxaemia. As an initial approach to understanding the thermoregulatory responses to cold and hypoxia in a small mammal, we explored the effects of acclimation to these two stressors on the body temperature (Tb) and the daily and ultradian Tb variations of Sprague-Dawley rats. As Tb is influenced by sleep-wake cycles, these Tb variations reflect underlying adjustments in set-point and thermosensitivity. The Tb of rats decreased precipitously during initial hypoxic exposure which was more pronounced in cold (Tb=33.4±0.13) than in room temperature (Tb=35.74±0.17) conditions. This decline was followed by an increase in Tb stabilising at a new level ~0.5 °C and ~1.4 °C below normoxic values at room and cold temperatures, respectively. Daily Tb variations were blunted during hypoxia with a greater effect in the cold. Ultradian Tb variations exhibited daily rhythmicity that disappeared under hypoxia, independent of ambient temperature. The adjustments in Tb during hypoxia and/or cold are in agreement with the hypothesis that an initial decrease in the Tb set-point is followed by its partial re-establishment with chronic hypoxia. This rebound of the Tb set-point might reflect cellular adjustments that would allow animals to better deal with low oxygen conditions, diminishing the drive for a lower Tb set-point. Cold and hypoxia are characteristic of high altitude environments. Understanding how mammals cope with changes in oxygen and temperature will shed light into their ability to colonize new environments along altitudinal clines and increase our understanding of how Tb is regulated under stimuli that impose contrasting physiological constraints.  相似文献   

12.
Di- and oligopeptide- binding protein OppAs play important roles in solute and nutrient uptake, sporulation, biofilm formation, cell wall muropeptides recycling, peptide-dependent quorum-sensing responses, adherence to host cells, and a variety of other biological processes. Soluble OppA from Thermoanaerobacter tengcongensis was expressed in Escherichia coli. The protein was found to be >95% pure with SDS–PAGE after a series of purification steps and the purity was further verified by mass spectrometry. The protein was crystallized using the sitting-drop vapour-diffusion method with PEG 400 as the precipitant. Crystal diffraction extended to 2.25 Å. The crystal belonged to space group C2221, with unit-cell parameters of a = 69.395, b = 199.572, c = 131.673 Å, and α = β = γ = 90°.  相似文献   

13.
The capacity for an ectothermic reptile to thermoregulate has implications for many components of its life history. Over two years, we studied thermoregulation in a population of Midland painted turtles (Chrysemys picta marginata) in a shallow, thermally variable wetland during summer in Northern Michigan. Mean body temperature (Tb) of free-ranging turtles was greater in 2008 (25.8 °C) than in 2010 (19.7 °C). Laboratory determined thermoregulatory set point (Tset) ranged from 25 °C (Tset-min) to 31 °C (Tset-max) and was lower during the fall (17–26 °C). Deviations of Tb distributions from field measured operative temperatures (Te) and indices of thermoregulation indicated that C. picta marginata were capable of a limited degree of thermoregulation. Operative temperatures and thermal quality (de=|Tset-minTe| and |TeTset-max|) cycled daily with maximal thermal quality occurring during late morning and late afternoon. The accuracy of thermoregulation (db=|Tset-minTb| and |TbTset-max|) was maximal (db values were minimal) as Tb declined and traversed Tset during the late afternoon–early evening hours and was higher on cloudy days than on sunny days because relatively low Te values decreased the number of Tb values that were above Tset. Our index of thermal exploitation (Ex=frequency of Tb observations within Tset) was 36%, slightly lower than that reported for an Ontario population of C. picta marginata. Regression of db (thermal accuracy) on de (thermal quality) indicated that turtles invested more in thermoregulation when thermal quality was low and when water levels were high than when they were low. There were no intersexual differences in mean Tb throughout the year but females had relatively high laboratory determined Tb values in the fall, perhaps reflecting the importance of maintaining ovarian development prior to winter.  相似文献   

14.
Rapidly cooling pigs after heat stress (HS) results in a pathophysiological condition, and because rapid temperature fluctuations may be associated with reduced reproductive success in sows, it lends itself to the hypothesis that these conditions may be linked. Objectives were to determine the effects of rapid cooling on thermal response and future reproductive success in pigs. Thirty-six replacement gilts (137.8±0.9 kg BW) were estrus synchronized and then 14.1±0.4 d after estrus confirmation, pigs were exposed to thermoneutral conditions (TN; n=12; 19.7±0.9°C) for 6 h, or HS (36.3±0.5°C) for 3 h, followed by 3 h of rapid cooling (HSRC; n=12; immediate TN exposure and water dousing) or gradual cooling (HSGC; n=12; gradual decrease to TN conditions) repeated over 2 d. Vaginal (TV) and gastrointestinal tract temperatures (TGI) were obtained every 15 min, and blood was collected on d 1 and d 2 during the HS and recovery periods at 180 and 60 min, respectively. Pigs were bred 8.3±0.8 d after thermal treatments over 2 d. Reproductive tracts were collected and total fetus number and viability were recorded 28.0±0.8 d after insemination. HS increased TV and TGI (P=0.01; 0.98 °C) in HSRC and HSGC compared to TN pigs. During recovery, TV was reduced from 15 to 105 min (P=0.01; 0.33 °C) in HSRC compared to HSGC pigs, but no overall differences in TGI were detected (P<0.05; 39.67 °C). Rapid cooling increased (P<0.05) TNFα compared to HSGC and TN pigs during recovery-d 1 (55.2%), HS-d 2 (35.1%), and recovery-d 2 (64.9%). Viable fetuses tended to be reduced (P=0.08; 10.5%) and moribund fetuses tended to be increased (P=0.09; 159.3%) in HSRC compared to HSGC and TN pigs. In summary, rapid cooling prior to breeding may contribute to reduced fetal viability and reproductive success in pigs.  相似文献   

15.
It is assumed that small herbivores produce negligible amounts of methane, but it is unclear whether this is a physiological peculiarity or simply a scaling effect. A respiratory chamber experiment was conducted with six rabbits (Oryctolagus cuniculus, 1.57 ± 0.31 kg body mass) and six guinea pigs (Cavia porcellus, 0.79 ± 0.07 kg) offered grass hay ad libitum. Daily dry matter (DM) intake and DM digestibility were 50 ± 6 g kg? 0.75 d? 1 and 55 ± 6% in rabbits and 59 ± 11 g kg? 0.75 d? 1 and 61 ± 3% in guinea pigs, respectively. Methane production was similar for both species (0.20 ± 0.10 L d? 1 and 0.22 ± 0.08 L d? 1) and represented 0.69 ± 0.32 and 1.03 ± 0.29% of gross energy intake in rabbits and guinea pigs, respectively. In relation to body mass (BM) guinea pigs produced significantly more methane. The data on methane per unit of BM obtained in this study and from the literature on the methane output of elephant, wallabies and hyraxes all lay close to a regression line derived from roughage-fed horses, showing an increase in methane output with BM. The regression, including all data, was nearly identical to that based on the horse data only (methane production in horses [L d? 1] = 0.18 BM [kg]0.97 (95%CI 0.92–1.02)) and indicates linear scaling. Because feed intake typically scales to BM0.75, linear scaling of methane output translates into increasing energetic losses at increasing BM. Accordingly, the data collection indicates that an increasing proportion of ingested gross energy is lost because relative methane production increases with BM. Different from ruminants, such losses (1%–2% of gross energy) appear too small in non-ruminant herbivores to represent a physiologic constraint on body size. Nevertheless, this relationship may represent a physiological disadvantage with increasing herbivore body size.  相似文献   

16.
Four series of phenylpicolinamide derivatives bearing 1H-pyrrolo[2,3-b]pyridine moiety (12ae, 13af, 14af and 15ai) were designed, synthesized and evaluated for the IC50 values against three cancer cell lines (A549, PC-3 and MCF-7) and c-Met kinase. Five selected compounds (13b, 15b, 15d, 15e and 15f) were further evaluated for the activity against HepG2 and Hela cell lines. Eighteen of the compounds showed excellent cytotoxicity activity and selectivity with the IC50 valuables in single-digit μM to nanomole range. Seven of them are equal to more active than positive control Foretinib against one or more cell lines. The most promising compound 15f showed superior activity to Foretinib, with the IC50 values of 1.04 ± 0.11 μM, 0.02 ± 0.01 μM and 9.11 ± 0.55 μM against A549, PC-3 and MCF-7 cell lines, which were 0.62 to 19.5 times more active than Foretinib (IC50 values: 0.64 ± 0.26 μM, 0.39 ± 0.11 μM, 9.47 ± 0.22 μM), respectively. Structure–activity relationships (SARs) and docking studies indicated that replacement of quinoline nucleus of the previous active compounds with 1H-pyrrolo[2,3-b]pyridine moiety maintained even improved the potent cytotoxic activity. The results suggested that the introduction of fluoro atoms to the aminophenoxy part of target compounds or the phenyl group of pyrimidine substituted on C-4 position was benefit for the activity.  相似文献   

17.
Most reptiles thermoregulate to achieve body temperatures needed for biological processes, such as digestion and growth. Temperatures experienced during embryogenesis may also influence post-hatching growth rate, potentially through influencing post-hatching choice of temperatures. We investigated in laboratory settings whether embryonic temperatures (constant 18 °C, 21 °C and 22 °C) influence selected body temperatures (Tsel) of juvenile tuatara (Sphenodon punctatus), providing a possible mechanism for differences in growth rates. We found that incubation temperature does not influence Tsel. Although the average daily mean Tsel was 21.6 ± 0.3 °C, we recorded individual Tsel values up to 33.5 °C in juvenile tuatara, which is higher than expected and above the panting threshold of 31–33 °C reported for adults. We found diel patterns of Tsel of juvenile tuatara, observing a general pattern of two apparent peaks and troughs per day, with Tsel being significantly lower around dawn and at 1500 h than any other time. When comparing our results with other studies on tuatara there is a remarkable consistency in mean Tsel of ~ 21 °C across tuatara of different ages, sizes and acclimatization histories. The ability of juvenile tuatara to withstand a wide range of temperatures supports their former widespread distribution throughout New Zealand and warrants further investigation into their plasticity to withstand climate warming, particularly where they have choices of habitat and the ability to thermoregulate.  相似文献   

18.
The purpose of this study was to investigate the effect of active pre-warming combined with three regimens of fluid ingestion: (1) fluid replacement equal to sweat rate (FF), (2) fluid replacement equal to half the sweat rate (HF), and (3) no fluid replacement (NF). Eight males cycled to voluntary fatigue at 70% of peak power output (PPO) in 31.3±0.4°C, 63.3±1.2% relative humidity in a randomised fashion in either of FF, HF or NF conditions. For each trial the time to fatigue test was preceded by 2×20 min active pre-warming periods where subjects also cycled at 70% PPO. Subjects commenced each exercise period with identical rectal temperatures (Tre). The rate of increase in Tre for each condition during the first 20 min of active pre-warming was not different. However, the rate of increase in Tre was significantly reduced in the second active pre-warming period for all fluid conditions but no differences between conditions were noted. During the fatigue test, the rate of increase in Tre for FF was 0.29°C h−1 and 0.58°C h−1 for HF but were not significantly different. The rate of increase in Tre for the NF trial was 0.92°C h−1 and was significantly higher compared to the FF trial. Overall mean skin temperatures and mean body temperatures were higher for NF compared to FF and HF. The rate of heat storage during the fatigue test was similar for FF (80.1±11.7 W m−2) and HF (73.0±13.7 W m−2) conditions but increased to 155.8±31.2 W m−2 (P<0.05) in the NF trial. The results indicate that fluid ingestion equal to sweat rate has no added benefit over fluid ingestion equal to half the sweat rate in determining time to fatigue over 40 min of sub-maximal exercise in warm humid conditions. Fluid restriction accelerates the rate of increase in Tre after 40 min of exercise, thereby reducing the time to fatigue. The data support the model that anticipation of impending thermal limits reduces efferent command to working skeletal muscle ensuring cellular preservation.  相似文献   

19.
Although the study of thermoregulation in insects has shown that infected animals tend to prefer higher temperatures than healthy individuals, the immune response and energetic consequences of this preference remain unknown. We examined the effect of environmental temperature and the energetic costs associated to the activation of the immune response of Tenebrio molitor larvae following a lipopolysaccharide (LPS) challenge. We measured the effect of temperature on immune parameters including phenoloxidase (PO) activity and antibacterial responses. Further as proximal and distal costs of the immune response we determined the standard metabolic rate (SMR) and the loss of body mass (mb), respectively. Immune response was stronger at 30 °C than was at 10 or 20 °C. While SMR at 10 and 20 °C did not differ between immune treatments, at 30 °C SMR of LPS-treated larvae was almost 25–60% higher than SMR of PBS-treated and naïve larvae. In addition, the loss in mb was 1.9 and 4.2 times higher in LPS-treated larvae than in PBS-treated and naïve controls. The immune responses exhibited a positive correlation with temperature and both, SMR and mb change, were sensitive to environmental temperature. These data suggest a significant effect of environmental temperature on the immune response and on the energetic costs of immunity.  相似文献   

20.
《Journal of thermal biology》2001,26(4-5):273-280
Eggs of Muscovy duck and domestic fowl were incubated at 37.5°C and relative air humidity of 70%. After 60 min the influence of lowered (31.5°C, 34.5°C and 28.5°C) Ta on heat production (HP) and temperature of the allantoic fluid (Taf) as a measure of core temperature was estimated for 3 h. The Q10 was calculated using the relationships between Taf and HP. HP dropped with decreasing Taf. The Q10 crossed the 2.0 threshold mostly between 34°C and 36°C Taf in dependence of Ta. Precocial birds are endothermic in the last third of incubation but these reactions have only an ultimate but not a proximate influence on efficiency of thermoregulation.  相似文献   

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