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1.
Batch transglutaminase (MTG) fermentations by Streptovertivillium mobaraense WSH-Z2 at various temperatures ranging from 25 to 35 °C were studied. Dry cell weight and MTG activity could reach their maximal values of 25.1 g/l and 2.94 U/ml, respectively at 30 °C. One typical equation was used to describe the relationship between specific growth rate and culture temperature by comparing several typical equations. Different lag time was observed under various culture temperature. The low lag time was observed under high culture temperature. X = –a 0(TT 0)2 + X 1 + a 1 (1 – exp(a 2 (TT 1))) and U = –a 0 (TT 0 )2 + U 0 + a 1 (1 – exp(a 2 (TT 1 ))) could be used to describe the relationship between temperature and the maximal dry cell weight as well as the maximal MTG activity at each temperature.  相似文献   

2.
When individual mice were examined, it was found that the colonic body temperatureT col of each individual within a genetically heterogeneous population tended to remain either above (warm) or below (cool) the population mean.T col of warm, but not cool, mice showed circadian variation. When exposed to aT a of 43° C, theT col of cool mice increased by as musch as 2.4° C more than that of warm mice for a given 15 min increment of heating at 43°C. Survival of mice after acute lethal heat load (LD75, –45°C) was significantly inversely correlated withT col. Small persistent differences in body temperature of individuals may indicate differing thermal adaptedness.  相似文献   

3.
Summary The Diamond Dove, Geopelia cuneata, is the world's second smallest (ca. 35 g) species of the columbid order. The Diamond Dove is endemic in the arid and semiarid Mulga and Spinifex regions of Central and Western Australia. It regularly encounters ambient temperatures (T a ) in its habitat above +40° C, especially when foraging for seeds on bare ground cover, and may be found at up to 40 km from water. This entails extreme thermal stress, with evaporative cooling constrained by limited water supply. Energy metabolism (M), respiration, body temperature (T a ) and water budget were examined with regard to physiological adaptations to these extreme environmental conditions. The zone of thermal neutrality (TNZ) extended from +34° C to at least +45° C. Basal metabolic rate (BMR) was 34.10±4.19 J g–1h–1, corresponding to the values predicted for a typical columbid bird. Thermal conductance (C) was higher than predicted. Geopelia cuneata showed the typical breathing pattern of doves, a combination of normal breathing at a stable frequency (ca. 60 min–1) at low T a and panting followed by gular flutter (up to 960 min–1) at high T a . At T a > +36° C, T a increased to considerably higher levels without increasing metabolic rate, i.e. Q10=1. This enabled the doves not only to store heat but also to save the amout of water that would have been required for evaporative cooling if T a had remained constant. The birds were able to dissipate more than 100% of the metabolic heat by evaporation at T a +44° C. This was achieved by gular flutter (an extremely effective mechanism for evaporation), and also by a low metabolic rate due to the low Q10 value for metabolism during increased T b . At lower T a , Geopelia cuneata predominantly relied on non-evaporative mechanisms during heat stress, to save water. Total evaporative water loss over the whole T a range was 19–33% lower than expected. In this respect, their small body size proved to be an important advantage for successful survival in hot and arid environments.Abbreviations and units Body Mass W (g) - Ambient Temperature T a (°C) - Body Temperature T b (°C) - Thermoneutral Zone (TNZ) - Metabolism M (J g–1 h–1) - Thermal Conductance C - wet Thermal Conductance C wet (J g–1 h–1 °C–1) - Evaporative Water Loss EWL (mg H2O g–1 h–1) - Evaporative Heat Loss EHL (J g–1 h–1) - Breathing Frequency F (breaths min–1) - Tidal Volume V t (ml breath–1) - Standard Temperature Pressure Dry STPD - Body Temperature Pressure Saturated BTPS - Respiratory Quotient RQ - n.s. not significant (P>0.05) - n number of experiments  相似文献   

4.
Summary Body temperature (T b), oxygen consumption , thermal conductance (C) and evaporative water loss (EWL) were measured at various air temperatures (T a) in two starlings which evolved in the tropics: a migratory species from a temperate climate,Sturnus vulgaris, and a resident, desert species,Onychognathus tristrami (Aves, Passeriformes, Sturnidae).AtT a's of 4–35°C both birds hadT b of 40.6°C. At 44°C,T b ofSturnus was 45.8°C and that ofOnychognathus 43.3°C.T a of 44°C was tolerated only byOnychognathus. The thermoneutral zone (TNZ) ofSturnus was in theT a range of 29.5°C–36.5°C, that ofOnychognathus 21.5–36.5°C. ofSturnus within its TNZ (BMR) was 2.37 ml O2 g–1 h–1, which is close to the expected BMR; that ofOnychognathus, 1.67 ml O2 g–1 h–1, is only 74% of the expected. AtT a'sNZ,C ofSturnus was twice as high as that ofOnychognathus and 1.68 times the expected value, whereasC ofOnychognathus was only 94% of the expected. At highT a'sOnychognathus had higherC thanSturnus. At either low or highT a's EWL ofSturnus was greater than ofOnychognathus.The responses shown bySturnus are typical of a tropical bird living in a moderate environment. This indicates that neither in USSR where it spends the summer, nor in Israel where it spends the winter, is this starling exposed to extreme temperatures.Onychognathus is better adapted not only to high but also to the low temperatures prevailing in mountainous regions of the desert.Symbols and abbreviations BMR basal metabolic rate - C thermal conductance - EWL evaporative water loss - HE evaporative heat loss - HP heat production - TNZ thermoneutral zone  相似文献   

5.
Summary The effects of different ambient temperatures (T a) on gas exchange and ventilation in deer mice (Peromyscus maniculatus) were determined after acclimation to low and high altitude (340 and 3,800 m).At both low and high altitude, oxygen consumption ( ) decreased with increasingT a atT a from –10 to 30 °C. The was 15–20% smaller at high altitude than at low altitude atT a below 30 °C.Increased atT a below thermoneutrality was supported by increased minute volume ( ) at both low and high altitude. At mostT a, the change in was primarily a function of changing respiration frequency (f); relatively little change occurred in tidal volume (V T) or oxygen extraction efficiency (O2EE). AtT a=0 °C and below at high altitude, was constant due to decliningV T and O2EE increased in order to maintain high .At high altitude, (BTP) was 30–40% higher at a givenT a than at low altitude, except atT a below 10 °C. The increased at high altitude was due primarily to a proportional increase inf, which attained mean values of 450–500 breaths/min atT a below 0 °C. The (STP) was equivalent at high and low altitude atT a of 10 °C and above. At lowerT a, (STPD) was larger at low altitude.At both altitudes, respiratory heat loss was a small fraction (<10%) of metabolic heat production, except at highT a (20–30 °C).Abbreviations EHL evaporative heat loss - f respiration frequency - HL a heat loss from warming tidal air - HL e evaporative heat loss in tidal air - HL total respiratory heat loss - MHP metabolic heat production - O 2 EE oxygen extraction efficiency - RQ respiratory quotient - T a ambient temperature - T b body temperatureT lc lower critical temperature - carbon dioxide production - evaporative water loss - oxygen consumption - minute volume - V T tidal volume  相似文献   

6.
Summary Adelie penguins (Pygoscelis adeliae) experience a wide range of ambient temperatures (T a) in their natural habitat. We examined body temperature (T b), oxygen consumption ( ), carbon dioxide production ( ), evaporative water loss ( ), and ventilation atT a from –20 to 30 °C. Body temperature did not change significantly between –20 and 20°C (meanT b=39.3°C).T b increased slightly to 40.1 °C atT a=30°C. Both and were constant and minimal atT a between –10 and 20°C, with only minor increases at –20 and 30°C. The minimal of adult penguins (mean mass 4.007 kg) was 0.0112 ml/[g·min], equivalent to a metabolic heat production (MHP) of 14.9 Watt. The respiratory exchange ratio was approximately 0.7 at allT a. Values of were low at lowT a, but increased to 0.21 g/min at 30°C, equivalent to 0.3% of body mass/h. Dry conductance increased 3.5-fold between –20 and 30°C. Evaporative heat loss (EHL) comprised about 5% of MHP at lowT a, rising to 47% of MHP atT a=30°C. The means of ventilation parameters (tidal volume [VT], respiration frequency [f], minute volume [I], and oxygen extraction [ ]) were fairly stable between –20 and 10°C (VT did not change significantly over the entireT a range). However, there was considerable inter- and intra-individual variation in ventilation patterns. AtT a=20–30°C,f increased 7-fold over the minimal value of 7.6 breaths/min, and I showed a similar change. fell from 28–35% at lowT a to 6% atT a=30°C.Abbreviations C thermal conductance - EHL evaporative heat loss - oxygen extraction - f respiratory frequency - MHP metabolic heat production - evaporative water loss - LCT lower critical temperature - RE respiratory exchange ratio - T a ambient temperature - T b body temperature - rate of oxygen consumption - rate of carbon dioxide production - I inspiratory minute volume - VT tidal volume  相似文献   

7.
Thermoregulatory sweating [total body (m sw,b), chest (m sw,c) and thigh (m sw,t) sweating], body temperatures [oesophageal (T oes) and mean skin temperature (T sk)] and heart rate were investigated in five sleep-deprived subjects (kept awake for 27 h) while exercising on a cycle (45 min at approximately 50% maximal oxygen consumption) in moderate heat (T air andT wall at 35° C. Them sw,c andm sw,t were measured under local thermal clamp (T sk,1), set at 35.5° C. After sleep deprivation, neither the levels of body temperatures (T oes,T sk) nor the levels ofm sw, b,m sw, c orm sw, t differed from control at rest or during exercise steady state. During the transient phase of exercise (whenT sk andT sk,1 were unvarying), them sw, c andm sw, t changes were positively correlated with those ofT oes. The slopes of them sw, c versusT oes, orm sw, t versusT oes relationships remained unchanged between control and sleep-loss experiments. Thus the slopes of the local sweating versusT oes, relationships (m sw, c andm sw, t sweating data pooled which reached 1.05 (SEM 0.14) mg·cm–2·min–1°C–1 and 1.14 (SEM 0.18) mg·cm–2·min–1·°C–1 before and after sleep deprivation) respectively did not differ. However, in our experiment, sleep deprivation significantly increased theT oes threshold for the onset of bothm sw, c andm sw, t (+0.3° C,P<0.001). From our investigations it would seem that the delayed core temperature for sweating onset in sleep-deprived humans, while exercising moderately in the heat, is likely to have been due to alterations occurring at the central level.  相似文献   

8.
Summary Breathing frequencyF r of resting blue-naped mousebirdsUrocolius macrourus lies between 50–70 per min and correlates directly with ambient temperatureT a and energy metabolismM. The nocturnal mean energy intake per breath varies between 5.6–17.7 mJ/g. At highT a the birds show gular fluttering with a relatively constantF r of about 460 min–1.M shows a constant absolute day-night difference of 25 J/g·h; the relative differences areT a-dependent between 36–168% (lower values at lowerT a). Thermal conductance is 2.10–2.15 J/g·h·°C (predicted 2.67), indicating a good insulation. Basal metabolic rate BMR is reduced by 63% compared to predicted values. At aT a-range of +8–36 °C the birds are normothermic. Below this range nocturnalT b andM decrease slightly with fallingT a. The birds show partial heterothermia (shallow hypothermia). Clustering is an effective energy saving strategy which allows loweringM with keeping highT b even at lowT a.Oxygen-intake is controlled byF r as well as by tidal volumeV t inT a-dependent changing portions.V T can vary between 0.29–0.91 ml (mean value 49.7 ml).Abbreviations T a ambient temperature - T b body temperature - M energy metabolism - F r breathing frequency - V T tidal volume - BMR basal metabolic rate - TNP thermoneutral point  相似文献   

9.
A comparison of the thermoregulation of water foraging wasps (Vespula vulgaris, Polistes dominulus) under special consideration of ambient temperature and solar radiation was conducted. The body surface temperature of living and dead wasps was measured by infrared thermography under natural conditions in their environment without disturbing the insects’ behaviour. The body temperature of both of them was positively correlated with Ta and solar radiation. At moderate Ta (22–28 °C) the regression lines revealed mean thorax temperatures (Tth) of 35.5–37.5 °C in Vespula, and of 28.6–33.7 °C in Polistes. At high Ta (30–39 °C) Tth was 37.2–40.6 °C in Vespula and 37.0–40.8 °C in Polistes. The thorax temperature excess (TthTa) increased at moderate Ta by 1.9 °C (Vespula) and 4.4 °C (Polistes) per kW−1 m−2. At high Ta it increased by 4.0 °C per kW−1 m−2 in both wasps. A comparison of the living water foraging Vespula and Polistes with dead wasps revealed a great difference in their thermoregulatory behaviour. At moderate Ta (22–28 °C) Vespula exhibited distinct endothermy in contrast to Polistes, which showed only a weak endothermic activity. At high Ta (30–39 °C) Vespula reduced their active heat production, and Polistes were always ectothermic. Both species exhibited an increasing cooling effort with increasing insolation and ambient temperature.  相似文献   

10.
Summary Stubble quail and King quail are both native to Australia although Stubble quail extend into more arid environments than do King quail. In this study, the responses of body temperature (T b), heart rate (f h), respiration rate (f r) and rates of gular flutter (f g) were measured in response to ambient temperatures (T a) ranging from 20 °C to 50 °C. Both species exhibited hyperthermia atT a in excess of 38–39 °C although both species maintainedT b lower thanT a atT a above 42 °C. Respiration rate remained relatively constant until the onset of panting, just prior to the commencement of gular flutter. The onset of panting and gular flutter in both species was relatively sudden and occurred at a meanT a of 38.1 °C for Stubble quail (meanT b of 42.5 °C) and a significantly higherT a of 40.9 °C but similar meanT b of 42.1 °C for King quail. Gular flutter appeared to occur synchronously with respiration and showed some tendency to increase withT b. The percentage of time spent in gular flutter showed a direct increase withT b. Heart rate tended to decrease with increasingT a in King quail while remaining relatively constant in Stubble quail. However, the relationship was not consistent and a great deal of variability existed between individuals. The two species are similar in their responses to heat stress and in general these responses do not reflect their different natural habitats.Symbols f h heart rate - f r respiratory rate - f g rate of gular fluttering  相似文献   

11.
Summary Djungarian hamsters,Phodopus sungorus (31.1 g body weight) were exposed to ambient temperatures (T a ) between –35°C and +34°C. They tolerated severe cold stress but were less able to withstand heat. At –35° CT a , normal body temperature was maintained for several hours. Thereby maximum thermal insulation was calculated at 1.1 g·°C/mW, which is only slightly higher than expected from the hamsters body size. High levels of heat production (60 to 90 m W/g) were maintained for several hours, suggesting that well developed means of heat production are the main reason for cold tolerance of the Djungarian hamster.  相似文献   

12.
Summary The effects of various convective and temperature regimes on heat production, evaporative heat loss, and thermal resistance were studied in deer mice,Peromyscus maniculatus. Heat production (measured as oxygen consumption) increased with increasing wind speed (V) and decreasing ambient temperature (T a), except atT a=35°C which was thermoneutral for allV from 0.05 through 3.75 m/s. Evaporative water loss ( ) increased with increasingT a, but wind had little effect on except at highT a. In the absence of forced convection, the animals' total resistance to heat transfer (r t) was high and stable atT a below thermoneutrality. However, at highV ther t increased steadily with decreasingT a. Although deer mice rarely experience high wind speeds in natural microhabitats, the convective regime is nevertheless important in determining rates of heat loss, and must be considered in studies of ecological energetics.Symbols and Abbreviations A animal surface area - HP n net metabolic heat production - EHL evaporative heat loss - MHP metabolic heat production - r t total resistance to heat transfer - r ext external resistance component of rt - RQ respiratory quotient - pc p volumetric specific heat of air - T a ambient temperature - t b body temperature - t e operative, or equivalent blackbody temperature of the environment - T sk skin temperature - T es standard operative temperature - V wind speed - oxygen consumption - carbon dioxide production - evaporative water loss  相似文献   

13.
Summary Instantaneous oxygen consumption, muscle potential frequency, thoracic and ambient temperature were simultaneously measured during heating in individual workers and drones of honey bees. Relationships between these parameters and effects of thoracic temperature on power input and temperature elevation were studied. Oxygen consumption increased above basal levels only when flight muscles became active. Increasing muscle potential frequencies correlated with elevated oxygen consumption and raised thoracic temperature. The difference between thoracic and ambient temperature and oxygen consumption were linearly related. Oxygen consumption per muscle potential (l O2 · g –1 thorax · MP–1) was two-fold higher in drones than in workers. However, oxygen consumption for heating the thorax (l O2 · g –1 thorax · (Tth-Ta) · °C–1) was nearly the same in workers and drones. Thoracic temperature affected the amount of oxygen consumed per muscle potential (R10=1.5). Achieved temperature elevation per 100 MP was more temperature sensitive in drones (R10=6–10) than in workers (R10=3.6). Q10 values for oxygen consumption were 3 in workers and 4.5–6 in drones. Muscle potential frequency decreased with a Q10=1.8 in workers and 2.7 in drones. Heating behaviour of workers and drones was different. Drones generated heat less continuously than workers, and showed greater interindividual variability in predilection to heat. However, the maximal difference between ambient and thoracic temperature observed was 22 °C in drones and 14 °C in workers, indicating greater potential for drones.Abbreviations DL dorsal-longitudinal muscle - DV dorsoventral muscle - MP muscle potential - T a ambient temperature - T th thoracic temperature  相似文献   

14.
This study examines the ventilatory physiology of the numbat (Myrmecobius fasciatus), a small to medium-sized (550 g) termitivorous marsupial. Ventilatory parameters at thermoneutrality reflect the slightly low (83% of predicted) basal metabolic rate of the numbat, with ventilation frequency (ƒR; 30.6±3.65 breaths min–1), tidal volume [VT; 6.0±0.66 ml at body temperature and pressure, saturated (BTPS)] and consequently minute volume (VI; 117.7±15.22 ml min–1; BTPS) all being 80–87% of that expected for a marsupial of similar body mass. Oxygen extraction was 27.7±1.37% in the thermoneutral zone. As is typical of marsupials, numbats accommodated increased oxygen consumption rates at ambient temperatures (T a) below the thermoneutral zone by increasing minute volume (up to 411.2±43.98 ml min–1; BTPS at T a=10 °C) rather than oxygen extraction. Minute volume at 10 °C increased more by changes in ventilation frequency (up to 45.5±4.85 breaths min–1) than tidal volume (9.4±1.03 ml, BTPS), as is also typical for a small-medium sized marsupial.Abbreviations BMR basal metabolic rate - BTPS body temperature and pressure, saturated - EO 2 oxygen extraction - ƒ R ventilation frequency - STPD standard temperature and pressure, dry - T a ambient temperature - T b body temperature - TNZ thermoneutral zone - V I minute volume - V T tidal volume - O 2 oxygen consumption rate Communicated by I.D. Hume  相似文献   

15.
The aim of this study was to evaluate the thermoregulatory changes induced by 27-h of sleep deprivation (SD) in men at rest both in a comfortable ambient temperature and in cold air. A group of 12 male subjects were placed in a comfortable ambient temperature (dry bulb temperature,T db = 25° C, relative humidity, rh = 40%–50% , clothing insulation = 1 clo) for 1 h and then they were submitted to a standard cold air test in a climatic chamber for 2h (T db=1° C, rh = 40%–50%, wind speed = 0.8 m·s–1, nude), before and after 27 h of sleep deprivation. Thermoregulatory changes (rectal temperature,T re; mean skin temperature, sk; metabolic heat production ) were monitored continuously. At comfortable ambient temperature, no significant change was observed after SD forT re, sk and . During the cold test,T re did not change but sk and were higher after SD (P<0.05). Increased (+ 6%,P < 0.05) was related to earlier and higher shivering, with a possible increase in the sensitivity of the thermoregulatory system as shown by the shorter time to onset of continous shivering (d): 8.66 (SEM 1.33) min versus 28.20 (SEM 1.33) min (P < 0.001) and by a higher sk observed at d: 27.60 (SEM 1.40)° C versus 21.40 (SEM 0.60)° C (P < 0.001). These results were associated with higher cold sensations and shivering following SD. They also suggested that SD modified thermoregulatory responses at a central level especially in a cold environment.  相似文献   

16.
Summary A stopped-flow rapid reaction apparatus was used for measuring changes in extracellular pH (pH o ) of red cell suspensions under conditions wheredpH o /dt was determined by the rate of HCO 3 /X exchange across the membrane (X =Cl, Br, F, I, NO 3 or SCN). The rate of the exchange at 37°C decreased forX in the order: Cl>Br>F>I>NO 3 >SCN, with rate constants in the ratios 10.860.770.550.520.31. When HCO 3 is exchanged for Cl, Br, F, NO 3 or SCN, a change in the rate-limiting step of the process takes place at a transition temperature (T T ) between 16 and 26°C. In I medium, however, no transition temperature is detected between 3 and 42°C. AlthoughT T varies withX , the activation energies both above and belowT T are similar for Cl, Br, NO 3 and F. The values of activation energy are considerably higher whenX =I or SCN. The apparent turnover numbers calculated for HCO 3 /X exchange (except forX =I) at the correspondingT T ranged from 140 to 460 ions/site ·sec for our experimental conditions. These findings suggest that: (i) HCO 3 /X exchange for allX studied takes place via the rapid anion exchange pathway; (ii) the rate of HCO 3 /X exchange is influenced by the specific anions involved in the 11 obligatory exchange; and (iii) the different transition temperatures in the Arrhenius diagrams of the HCO 3 /X exchange do not seem to be directly related to a critical turnover number, but may be dependent upon the influence ofX on protein-lipid interactions in the red blood cell membrane.  相似文献   

17.
Pigeon flight in a wind tunnel   总被引:2,自引:0,他引:2  
Summary Core temperatureT c, breast temperatureT s–br and leg temperatureT s–1 were measured simultaneously in pigeons during rest and flight in a wind tunnel, using thermistors.MeanT c at rest is 39.8±0.7°C and is independent of ambient temperatureT a (10–30°C). In the first minutes of flight,T c increases to 1.5–3.0°C above resting level and remains at this higher level. This hyperthermia increases withT a (v=const.). It is±constant in the lowT a range (10.6–13.9°C) at flight speeds v ranging from 10–18 m s–1 and normal body mass, but increases with v and elevated body mass in the highT a range (23.7–28.8°C). T s–1 is adapted toT a at rest and increases in flight up to 3–4°C belowT c. This increase inT s–1 is linear toT a. T s–br is always lower thanT c, in extreme cases reaching restingT c in flight.Supported by the Deutsche Forschungsgemeinschaft  相似文献   

18.
Rectal (Tre), mean skin temperature ( sk) and sweating rate ( ) were measured in 4 residents of temperate climate under acute moderate heat exposure (designated EE in such an experimental situation), after 3 weeks in India (designated as EI) and in 8 Indian residents (designated as II) both at rest and during submaximal exercises at 2 different intensities. At rest, Tre is higher in EI (37.6°C) than in EE (36.8°C, P<0.01) and reaches 37.8°C in II. At the end of exercise, the increment in Tre seems to depend on work load only and to be independent of thermal environment; S follows a similar pattern in the 3 groups of subjects: sk is altered neither by exercise nor acclimatization. Under chronic heat exposure compared to acute conditions: (1) identical is achieved with higher Tre and similar sk so that the linear relationships vs Tre is shifted to the right. (2) the Tresk difference is greater at rest and during exercise: hence, skin blood flow, calculated from heat balance equation diminishes. In hot climate, a rise in Tre seems to be an adaptive response which allows the body to reduce skin blood flow.  相似文献   

19.
Influence of soil temperature on methane emission from rice paddy fields   总被引:18,自引:2,他引:16  
Methane emission rates from an Italian rice paddy field showed diel and seasonal variations. The seasonal variations were not closely related to soil temperatures. However, the dieL changes of CH4 fluxes were significantly correlated with the diel changes of the temperature in a particular soil depth. The soil depths with the best correlations between CH4 flux and temperature were shallow (1–5cm) in May and June, deep (10–15cm) in June and July, and again shallow (1–5 cm) in August. Apparent activation energies (Ea) calculated from these correlations using the Arrhenius model were relatively low (50–150 kJ mol–1) in May and June, but increased to higher values (80–450 kJ mol–1) in August. In the laboratory, CH4 emission from two rice cultures incubated at temperatures between 20 and 38°C showed E . values of 41 and 53 kJ mol–1) Methane production in anoxic paddy soil suspensions incubated between 7 and 43°C showed E values between 53 and 132 kJ mol–1 with an average value of 85 kJ mol–1) and in pure cultures of hydrogenotrophic methanogenic bacteria E a values between 77 and 173 (average 126) kJ mol–1. It is suggested that diel changes of soil properties other than temperature affect CH4 emission rates, e.g. diel changes in root exudation or in efficiency of CH4 oxidation in the rhizosphere.  相似文献   

20.
Summary Values for basal metabolism, standard tidal volume (V T), standard minute volume ( ), and mean extraction efficiency (EO2) in the thermal neutral zone (TNZ) inAgapornis roseicollis (1.84 ml·min–1; 0.95 ml·br–1, STPD; and 33.3 ml·min–1, STPD; and 22.5%; respectively) were all very similar to values for these parameters previously measured inBolborhynchus lineola, a similarly sized, closely related species from a distinctly different habitat.Having both a lower critical temperature (Tlc) below and an upper critical temperature (Tuc) above those ofB. lineola, the TNZ ofA. roseicollis extended from 25° to at least 35°C. The thermal conductance below the TNZ ofA. roseicollis was 14% less than that ofB. lineola. Therefore, at 5°C the standard metabolic rate (SMR) of the former is 17% less than that of the latter, and at 35°C it is 20% less. At 5°CA. roseicollis has a lower EO2 and at 35°C a higher EO2 than that ofB. lineola. The patterns of resting energy metabolism and of ventilation ofA. roseicollis and ofB. lineola are consistent with the former species being better suited to living in a more variable thermal environment than the latter.MeanV T has a weak positive correlation with the rate of oxygen consumption ( ) at a constant ambient temperature (T a) but a much stronger correlation when resting increases in response to a decrease inT a.V t is the only ventilatory parameter which is linearly correlated toT a from 35° to –25°C. The data suggest thatT a may have a regulatory effect onV T somewhat independent of or .  相似文献   

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