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1.
D. B. Sattelle K. H. Langley A. L. Obaid B. M. Salzberg 《European biophysics journal : EBJ》1987,15(2):71-76
Quasi-elastic laser light scattering has been used to investigate the size and dispersity of synaptosomes and synaptic vesicles isolated from optic lobes of the squid Loligo pealei. Synaptosomal fractions were highly polydisperse (
) and the mean diameter (
) ranged from 0.5–2.0 m. Size distribution histograms yielded two major components — smaller particles (
) and a larger group of particles (
). The heterogeneity of the synaptosomal particles detected in solution is in agreement with published data obtained using electron microscopy. Purified synaptic vesicle fractions also yielded complex particle size distribution data. A component with a mean diameter in the range 150–250 nm was detected, though a smaller particle (
) dominated the scattering signal. This smaller particle closely resembles in size the electron lucent vesicles seen in the majority of squid optic lobe nerve terminals when examined by electron microscopy. Osmotically-induced shirnkage and swelling of the synptosomes was detected. Depolarization by veratridine (1.0×10–4
M) did not result in a detectable change in the size of synaptosomal particles. 相似文献
2.
Jürgen M. Schmidt Richard R. Ernst Saburo Aimoto Masatsune Kainosho 《Journal of biomolecular NMR》1995,6(1):95-105
Summary A simple heteronuclear relayed E.COSY pulse sequence with a minimum number of pulses is proposed for the quantitative determination of heteronuclear three-bond J-coupling constants in uniformly 13C-enriched polypeptide samples. Numerous heteronuclear three-bond coupling constants, including
,
,
, and
, can be determined for each residue from a single heteronuclear relayed E.COSY spectrum. Couplings relevant for stereospecific assignments as well as for the determination of dihedral angles in the amino acid backbone and in side chains are obtained. The method is demonstrated on the uniformly 13C-enriched decapeptide antamanide (-Val1-Pro2-Pro3-Ala4-Phe5-Phe6-Pro7-Pro8-Phe9-Phe10-). 相似文献
3.
B. Culik A. J. Woakes D. Adelung R. P. Wilson N. R. Coria H. J. Spairani 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1990,160(1):61-70
Summary The energy requirements of Adélie penguin (Pygoscelis adeliae) chicks were analysed with respect to body mass (W, 0.145–3.35 kg, n=36) and various forms of activity (lying, standing, minor activity, locomotion, walking on a treadmill). Direct respirometry was used to measure O2 consumption (
) and CO2 production. Heart rate (HR, bpm) was recorded from the ECG obtained by both externally attached electrodes and implantable HR-transmitters. The parameters measured were not affected by hand-rearing of the chicks or by implanting transmitters. HR measured in the laboratory and in the field were comparable. Oxygen uptake ranged from
in lying chicks to
at maximal activity, RQ=0.76. Metabolic rate in small wild chicks (0.14–0.38 kg) was not affected by time of day, nor was their feeding frequency in the colony (Dec 20–21). Regressions of HR on
were highly significant (p< 0.0001) in transmitter implanted chicks (n=4), and two relationships are proposed for the pooled data, one for minor activities (
), and one for walking (
). Oxygen consumption, mass of the chick (2–3 kg), and duration of walking (T, s) were related as
, whereas mass-specific O2 consumption was related to walking speed (S, m·s-1) as
.Abbreviations
bpm
beats per minute
-
D
distance walked (m)
-
ECG
electrocardiogram
-
HR
heart rate (bpm)
-
ns
number of steps
-
RQ
respiratory quotient
-
S
walking speed (m·s-1)
-
T
time walked (s)
-
W
body mass (kg) 相似文献
4.
Veronique Billat Jean C. Renoux Jacques Pinoteau Bernard Petit Jean P. Koralsztein 《European journal of applied physiology and occupational physiology》1994,69(3):271-273
The aim of this study was to measure running times to exhaustion (Tlim) on a treadmill at 100% of the minimum velocity which elicits
max
max in 38 elite male long - distance runners
max = 71.4 ± 5.5 ml.kg–1.min–1 and
max = 21.8 ± 1.2 km.h–1). The lactate threshold (LT) was defined as a starting point of accelerated lactate accumulation around 4 mM and was expressed in
max. Tlim value was negatively correlated with
max (r = -0.362, p< 0.05) and
max (r = –0.347, p< 0.05) but positively with LT (%v
max) (r = 0.378, p < 0.05). These data demonstrate that running time to exhaustion at
max in a homogeneous group of elite male long-distance runners was inversely related to
max and experimentally illustrates the model of Monod and Scherrer regarding the time limit-velocity relationship adapted from local exercise for running by Hughson et al. (1984) . 相似文献
5.
Uwe Hoffmann Dieter Eβfeld Dieter Leyk Hans-Georg Wunderlich Jürgen Stegemann 《European journal of applied physiology and occupational physiology》1994,69(2):93-97
Power-oxygen uptake (
) frequency responses can be used to predict
responses to arbitrary exercise intensity patterns. It is still an open question for which range of exercise intensities such computed
response patterns yield valid predictions. In the present study, we determined the power-
frequency response of nine sports students by means of pseudo-randomised switching between 20 W and 80 W during upright and supine cycle exercise. Starting from a baseline of 20 W each subject also performed sustained step increases to 40 W, 80 W, 120 W, and 160 W in both positions. The individual
step responses were then compared with the expected
time-courses predicted on the basis of the individual
frequency responses. The comparison showed a close agreement for the 20 W–40 W and 20 W–80 W steps in both positions. With larger step amplitudes the
kinetics became increasingly slower than the predicted
time course in both positions. During additional ramp tests (10 W · 30 s–1) whole blood lactic acid concentration [1a–]b tended to be higher in the supine position at exercise intensities higher than 160 W. The mean power at 4 mmol · 1–1 [la–]b amounted to 234 (SD 32) W and 253 (SD 44) W (P<5%) in the supine and the upright position, respectively. The maximal oxygen uptake relative to body mass was not found to be significantly different [upright, mean 57 (SD 10) ml · (min · kg)–1;supine, mean 54 (SD 10) ml · (min · kg)]. These findings would suggest that for a range of mild exercise intensities
kinetics are not appreciably influenced by the step amplitude or by cardiovascular changes associated with the upright and the supine position. 相似文献
6.
D. L. Evans R. J. Rose 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1988,157(6):791-799
Summary Six Standardbred horses were used to evaluate the time course of pulmonary gas exchange, ventilation, heart rate (HR) and acid base balance during different intensities of constant-load treadmill exercise. Horses were exercised at approximately 50%, 75% and 100% maximum oxygen uptake (
max) for 5 min and measurements taken every 30 s throughout exercise. At all work rates, the minute ventilation, respiratory frequency and tidal volume reached steady state values by 60 s of exercise. At 100%
max, the oxygen consumption (
) increased to mean values of approximately 130 ml/kg·min, which represents a 40-fold increase above resting
. At the low and moderate work rates,
showed no significant change from 30 s to 300 s of exercise. At the high work rate, the mean
at 30 s was 80% of the value at 300 s. The HR showed no significant change over time at the moderate work rate but differing responses at the low and high work rates. At the low work rate, the mean HR decreased from 188 beats/min at 30 s to 172 beats/min at 300 s exercise, whereas at the high work rate the mean HR increased from 204 beats/min at 30 s to 221 beats/min at 300 s exercise. No changes in acid base status occurred during exercise at the low work rate. At the moderate work rate, a mild metabolic acidosis occurred which was nonprogressive with time, whereas the high work rate resulted in a progressive metabolic acidosis with a base deficit of 16 mmol/l by 300 s exercise. It is concluded that the kinetics of gas exchange during exercise are more rapid in the horse than in man, despite the relatively greater change in
in the horse when going from rest to high intensity exercise.Symbols and abbreviations E
minute ventilation
-
V
T
tidal volume
-
oxygen uptake
-
carbon dioxide output
-
oxygen pulse
-
ventilatory equivalent for oxygen
-
ventilatory equivalent for carbon dioxide
- R
respiratory exchange ratio
- HR
heart rate
- SBC
standard bicarbonate
- STPD
standard temperature and pressure dry
- BTPS
body temperature and pressure saturated
-
arterial oxygen content
-
arteriovenous oxygen content difference
- Rf
respiratory frequency 相似文献
7.
Pierre Dejours Jean-Paul Truchot 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1988,158(3):387-391
Summary In the intertidal shore crab,Carcinus maenas, pH and
values of the prebranchial venous hemolymph,
and
, the PO2 values of the arterialized cardiac hemolymph,
, were measured, and the ventilatory activity was assessed by measuring the hydrostatic pressures at the exits of the epibranchial cavities, under four environmental conditions: normoxic water, normoxic air, hypoxic gas, hyperoxic gas.In the crab breathing normoxic air,
was lower and
higher than in animals breathing normoxic water. With the switch to hypoxic gas, ventilation increased and
and
decreased. With the switch to hyperoxic gas, ventilation decreased,
and
increased and
decreased.Thus these crabs breathing air were not as well oxygenated as when breathing air-equilibrated water, and because of their low
, they were relatively hypervetilating and hypocapnic compared to air-breathing vertebrates. Hyperoxic breathing, increasing
and reducing ventilatory drive, led to increased
. Conversely,
was reduced by hypoxic breathing. These observations suggest that the gas exchanger of intertidal crabs is not as successfully designed for air breathing as that of land-colonizing insects and air-breathing vertebrates. 相似文献
8.
V. Billat F. Dalmay M. T. Antonini A. P. Chassain 《European journal of applied physiology and occupational physiology》1994,69(3):196-202
The aim of this study was to estimate the characteristic exercise intensity
CL which produces the maximal steady state of blood lactate concentration (MLSS) from submaximal intensities of 20 min carried out on the same day and separated by 40 min. Ten fit male adults [maximal oxygen uptake
max 62 (SD 7) ml · min–1 · kg–1] exercisOed for two 30-min periods on a cycle ergometer at 67% (test 1.1) and 82% of
max (test 1.2) separated by 40 min. They exercised 4 days later for 30 min at 82% of
max without prior exercise (test 2). Blood lactate was collected for determination of lactic acid concentration every 5 min and heart rate and O2 uptake
were measured every 30 s. There were no significant differences at the 5th, 10th, 15th, 20th, 25th, or 30th min between
, lactacidaemia, and heart rate during tests 1.2 and 2. Moreover, we compared the exercise intensities
CL which produced the MLSS obtained during tests 1.1 and 1.2 or during tests 1.1 and 2 calculated from differential values of lactic acid blood concentration ([1a–]b) between the 30th and the 5th min or between the 20th and the 5th min. There was no significant difference between the different values of
CL [68 (SD 9), 71 (SD 7), 73 (SD 6),71 (SD 11) % of
max (ANOVA test,P<0.05). Four subjects ran for 60 min at their
CL determined from periods performed on the same day (test 1.1 and 1.2) and the difference between the [la–]b at 5 min and at 20 min ( ([la–]b)) was computed. The [la–]b remained constant during exercise and ranged from 2.2 to 6.7 mmol · l–1 [mean value equal to 3.9 (SD 1) mmol · l–1]. These data suggest that the
CL protocol did not overestimate the exercise intensity corresponding to the maximal fractional utilization of
max at MLSS. For half of the subjects the
CL was very close to the higher stage (82% of
max where an accumulation of lactate in the blood with time was observed. It can be hypothesized that
CL was very close to the real MLSS considering the level of accuracy of [la–]b measurement. This study showed that exercise at only two intensities, performed at 65% and 80% of
max and separated by 40 min of complete rest, can be used to determine the intensity yielding a steady state of [la–1]b near the real MLSS workload value. 相似文献
9.
High groundwater nitrate concentrations inhibit eutrophication of sulphate-rich freshwater wetlands 总被引:2,自引:0,他引:2
E.C.H.E.T. Lucassen A.J.P. Smolders A.L. van der Salm J.G.M. Roelofs 《Biogeochemistry》2004,67(2):249-267
During the last 60 years, pollution of the groundwater with
has greatly increased in many parts of Europe, as a consequence of excessive use of manure and synthetic fertilisers. Monitoring of groundwater-fed wetlands indicated that sediments with high
concentrations had the lowest Fe and
concentrations in the pore water. A comparison of two restored open water fens, differing in
supply via the groundwater, indicated that the redox potential and the sulphate (
) reduction rate were lower when the groundwater contained not only
but also high
concentrations. The lower
reduction rates in the
-rich open water fen were associated with lower
concentrations and the presence of plant species characteristic of clear water. In contrast, the higher
reduction rates in the
-poor open water fen were associated with very high
concentrations and massive development of plant species characteristic of eutrophic environments. Investigations at
-rich seepage sites in black alder carrs, showed that high
concentrations in the pore water caused chlorosis in the alder carr vegetation, due to lower availability of Fe in the pore water and less Fe uptake by the plants. Experimental desiccation of sediments proved that the
-rich seepage sites contained no oxidisable FeS
x
, contrary to
-poor locations, which became acidified and mobilised extremely high amounts of
due to FeS
x
oxidation. A laboratory experiment showed that
addition to sediments led to reduced releases of Fe,
and S2–, very likely due to the oxidation of reduced Fe and S compounds. Overall, the results confirmed that
is an energetically more favourable electron acceptor in anaerobic sediments than Fe and
, and that high
loads function as a redox buffer, preventing reduction of Fe and
. Limited
reduction prevents S2– -mediated mobilisation of
from Fe-
complexes. At a higher redox potential, reduced Fe, including FeS
x
, was oxidised, increasing the content of Fe(III) capable of binding
. This prevented increased
availability and the concomitant massive development of plant species characteristic of eutrophic environments. 相似文献
10.
P. Pic 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1978,123(2):155-162
Summary In seawater (SW)-adaptedMugil andFundulus, gill effluxes of Na+
and of Cl–
and the simultaneously recorded transgill potential (P.D.) differ according to whether they are measured in stressed or rested animals.In rested animals of the two species, transfer to Ringer's solution considerably reduces the P.D. but not
. InFundulus,
is also decreased. Transfer of the two species from SW to fresh water (FW) reduces
and
by 75 to 85% and leads to a large inversion of P.D. When K+ is added to FW, a gill depolarization occurs, as well as a large increase of
and
.These results suggest that: 1) the P.D. originates primarily from the diffusion of cations, the gill permeability to Na+ (
) being greater than that to Cl– (
), 2) a Cl–/Cl– exchange independent of P.D. is associated with the Cl– pump; 3) Cl– pump activity is linked to Na+/K+ exchange which in turn is associated to a Na+/Na+ exchange diffusion mechanism.In stressed individuals of the two species, the P.D. in SW, as well as the P.D. changes observed during transfer experiments, are considerably reduced. The decrease of
and
observed after transfer from SW to FW are also minimised. Changes are smaller inFundulus. The decrease of P.D. characterizing stressed animals may be at least in part due to a 3 to 4 fold increase of
which becomes equal to
in both species.As a result of stress, the K+-activated Na+ and Cl– excretion mechanisms are totally inhibited inFundulus and partially so inMugil.Stress response seems more intense inFundulus and recovery from stress faster inMugil. 相似文献
11.
Roger S. Seymour David Vleck Carol M. Vleck David T. Booth 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1987,157(4):413-422
Summary Eggs of the brush turkey (BT) and mallee fowl (MF) are incubated in mounds of soil and plant litter. Humidity in BT mounds is always near saturation (>99% RH), but in MF mounds it drops to lower values in summer (x=77% RH). Despite these high humidities, the eggs lose an average of 9.5% (BT) and 12.0% (MF) of their initial mass by evaporation before hatching. The rate of evaporation
increases during incubation several-fold due to large changes in water vapor conductance of the shell
and embryonic heat production. Values of
in fully incubated eggs in mound material are about 3–6 times higher than values obtained from unincubated eggs in desiccators. This effect depends on two factors: (1)
increases with ambient humidity, especially above 80% RH, possibly because the effective site of evaporation moves out along the walls of the pores in the eggshell. (2) Structural changes of the pores due to calcium absorption by the embryo directly increase
. The first factor is most important in BT eggs and the second is dominant in MF eggs. Production of metabolic heat by the embryo increases the vapor pressure difference across the shell and further increases
, especially in mounds of high humidity. The changes in pore structure are adaptive because they produce high conductances to respiratory gases and cause normal gas tensions within the egg at the end of development, yet
is low enough in early development to prevent excessive water loss. Water not lost by evaporation or taken up by the embryo is stored and released during hatching. A small amount of mass is lost during incubation by respiratory gas exchange.Abbreviations
BT
brush turkey
-
MF
mallee fowl
-
RH
relative humidity 相似文献
12.
Gill function in an elasmobranch 总被引:1,自引:0,他引:1
Gordon C. Grigg John Read 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1971,73(4):439-451
Summary Highly efficient oxygen uptake in elasmobranchs, as indicated by frequent excess of
over
has previously been ascribed to the operation of multicapillary rather than counter-current gas exchange by the gills. Analysis of models shows that, at maximum efficiency, a multicapillary system cannot account for values of
greater than
. In Port Jackson sharks Heterodontus portusjacksoni)
commonly exceeds
, which indicates the operation of a functional counter-current at the respiratory surface. The anatomical basis of this counter-current is provided by the demonstration that a continuous flow of water passes between the secondary lamellae into septal canals and thence via the parabranchial cavities to the exterior.Queen Elizabeth II Fellow. 相似文献
13.
Jacopo P. Mortola anna Noworaj 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1985,155(2):171-176
Summary The resting oxygen consumption
and breathing pattern of nine newborn and adult species (ranging in body size from mouse to human) have been compared on the basis of data collected from the literature. Minute ventilation
is similarly linked to
at both ages, the percent of
extracted as O2
about 2.2. Tidal volume/kg is an interspecies constant in newborns and adults, approximately 8 ml/kg. Breathing frequency decreases with the increase in size in a different way at the two ages: large species have newborns breathing at rates 2–3 times above the corresponding adults' values, while in the small species newborns and adults breathe at almost the same rate. Therefore the newborns of the smallest species have both
and
below the expected values, implying a greater inability to cope with the external demands than newborns of larger species. Several considerations indicate that in the smallest newborns the mechanical properties of the respiratory system could be a constraint to resting ventilations larger than observed. It is therefore possible that their low
is the cause, and not the effect, of the relatively small
. 相似文献
14.
Thermoregulation,gas exchange,and ventilation in Adelie penguins (Pygoscelis adeliae) 总被引:1,自引:0,他引:1
Mark A. Chappell Sherrie L. Souza 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1988,157(6):783-790
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
15.
Desulfovibrio vulgaris (strain Marburg) was grown on H2 and sulfate as sole energy source in a chemostat limited by the sulfate supply. The biomass concentration and the sulfate concentration in the culture were determined as a function of the dilution rate. From the data a K
S (saturation constant) for sulfate of 10 M, a max of 0.23 h–1, and a
of 13 g/mol were calculated. The organism was also grown in chemostat culture on H2 and sulfite, H2 and thiosulfate, and pyruvate (without sulfate).
was found to be 35 g/mol,
36 g/mol, and Y
pyr
max
10 g/mol. The growth yields are discussed with respect to ATP gains in dissimilatory sulfate reduction. 相似文献
16.
Effects of ambient temperature and altitude on ventilation and gas exchange in deer mice (Peromyscus maniculatus) 总被引:2,自引:1,他引:1
Mark A. Chappell 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1985,155(6):751-758
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
17.
Methanobacterium thermoautotrophicum was grown in continuous culture in a fermenter gassed with H2 and CO2 as sole carbon and energy sources, and in a medium which contained either NH4Cl or gaseous N2 as nitrogen source. Growth was possible with N2. Steady states were obtained at various gas flow rates with NH4Cl and with
and the maintenance coefficient varied with the gas input and with the nitrogen source. Growth of Methanococcus thermolithotrophicus in continuous culture in a fermenter gassed with H2, CO2 as nitrogen, carbon and energy sources was also examined.Abbreviations
molecular growth yield (g dry weight of cells per mol of CH4 evolved)
-
growth rate (h-1)
-
D
dilution rate (h-1)
- rate (h-1);
relation of Neijssel and Tempest and of Stouthamer and Bettenhaussen
-
energy 相似文献
18.
A small catchment on the Swedish West Coast has been studied over four years to determine S dynamics by using S isotope ratios. A Norway spruce dominated forest covers the catchment, and small peat areas occur in the lower parts of the catchment. The runoff
values varied both during the year, and from year to year. Over the period from February 1990 to December 1993, the
values ranged from — 1%. to +11%. Over the same period, the throughfall
values ranged from +1%. to +15%. There was no correlation (r
2= 0.01; Pr(F)=0.57) between
values in throughfall and runoff. Since the only input of S to the catchment is atmospheric deposition, the long-term runoff S mass flux is controlled by the deposition. Therefore, processes in the catchment are responsible for the variation in the runoff
values. During periods with
enriched runoff, bacterial dissimilatory SO
4
2–
reduction occurs in the catchment. After very dry periods, oxidation of this reduced S, which is32S-enriched, can be traced in runoff. Previous studies of the catchment have not been able to distinguish between: 1) oxidation of reduced S and dry deposition, and 2) reduction and adsorption. From the current study, it can be concluded that adsorption and dry deposition cannot cause the observed variation in runoff
. 相似文献
19.
Theodore L. Taigen Kentwood D. Wells 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1985,155(2):163-170
Summary The metabolic demands of vocalization byHyla versicolor were determined by measuring oxygen consumption and whole body lactate content of calling animals. A stepwise multiple regression analysis identified both calling rate (calls/h) and call duration (s/call) as significant determinants of oxygen consumption during calling. These two variables accounted for 84% of the total variation in oxygen consumption observed in calling frogs. Aerobic metabolism
increased linearly with calling rate and call duration, reaching a peak value of 1.7 ml O2/(g·h) at the highest vocalization effort. For comparison, metabolic rates of the same individuals were also measured during short bouts of vigorous locomotor exercise
induced by mechanical stimulation. The mean value of
was only 62% of the peak
, and 5 of 13 frogs had rates of oxygen consumption during calling that exceeded their
. Whole body lactate levels were measured in two samples of calling frogs, one collected early in the evening (2100–2115 h) and the other 1.5 h later (2230–2245 h). The frogs in the second sample had significantly lower lactate levels (0.10 mg/g) than the frogs collected early in the evening (0.22 mg/g). Hence, vocalization does not entail the use of anaerobic metabolism, although lactate levels may be slightly elevated at the onset of an evening of calling. Calling rates of unrestrained frogs in a large chorus were measured at regular intervals during an evening. During the first half hour of calling, rates increased gradually from an initial mean value of 600 calls/h at 2030 h to nearly 1400 calls/h at 2100 h. These data indicate that acoustic advertisement byHyla versicolor is among the most energetically expensive activities regularly undertaken by any anuran, and indeed, is the most demanding yet measured in an ectothermic vertebrate.Abbreviations
resting rate of oxygen consumption
-
maximum rate of oxygen consumption
-
rate of oxygen consumption during forced exercise
-
rate of oxygen consumption during calling 相似文献
20.
Jacques Mercier Daniel Le Gallais Marc Durand Christine Goudal Jean Paul Micallef Christian Préfaut 《European journal of applied physiology and occupational physiology》1994,69(6):525-529
We investigated whether the spontaneous transition between walking and running during moving with increasing speed corresponds to the speed at which walking becomes less economical than running. Seven active male subjects [mean age, 23.7 (SEM 0.7) years, mean maximal oxygen uptake (
), 57.5 (SEM 3.3) ml·kg –1·min –1, mean ventilatory threshold (VTh), 37.5 (SEM 3) ml·kg –1 ·min –1] participated in this study. Each subject performed four exercise tests separated by 1-week intervals: test 1,
and VTh were determined; test 2, the speed at which the transition between walking and running spontaneously occurs (ST) during increasing speed (increases of 0.5 km·h –1 every 4 min from 5 km·h –1) was determined; test 3, the subjects were constrained to walk for 4 min at ST, at ST ± 0.5 km·h –1 and at ST ± 1 km·h –1; and test 4, the subjects were constrained to run for 4 min at ST, at ST±0.5 km·-h –1 and at ST±1 km·h –1. During exercise, oxygen uptake (
), heart rate (HR), ventilation (
), ventilatory equivalents for oxygen and carbon dioxide (% MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGabmOvayaaca% WaaSbaaSqaaiaabweaaeqaaOGaai4laiqadAfagaGaamaaBaaaleaa% caqGYaaabeaakiaacYcacaqGGaGaaeiiaiqadAfagaGaamaaBaaale% aacaqGfbaabeaakiaac+caceWGwbGbaiaacaqGdbGaae4tamaaBaaa% leaacaaIYaaabeaaaaa!4240!\[\dot V_{\text{E}} /\dot V_{\text{2}} ,{\text{ }}\dot V_{\text{E}} /\dot V{\text{CO}}_2 \]), respiratory exchange ratio (R), stride length (SL), and stride frequency (SF) were measured. The results showed that: ST occurred at 2.16 (SEM 0.04) m·s –1;
, HR and speed at ST were significantly lower than the values measured at VTh (P< 0.001, P< 0.001 and P< 0.05, respectively);
changed significantly with speed (P< 0.001) but was greater during running than walking below ST (ST minus 1 km·h –1, P< 0.001; ST minus 0.5 km·h –1, P< 0.05) with the converse above ST (ST.plus 1 km·h –1, P<0.05), whereas at ST the values of
were very close [23.9 (SEM 1.1) vs 23.7 (SEM 0.8) ml·kg –1 · min –1 not significant, respectively, for walking and running]; SL was significantly greater during walking than running (P<0.001) and SF lower (P<0.001); and HR and
were significantly greater during running than walking below ST (ST minus 1 km·h –1, P<0.01; ST minus 0.5 km·h –1, P{<0.05) with the converse above ST (ST plus 1 km·h –1, P·< 0.05), whereas no difference appeared for
and R between the two types of locomotion. We concluded from this study that ST corresponded to the speed at which the energy expenditure of running became lower than the energy expenditure of walking but that the mechanism of the link needed further investigation. 相似文献