共查询到20条相似文献,搜索用时 31 毫秒
1.
Gregory K. Snyder Wesley W. Weathers 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1977,117(3):291-301
Summary Resting rates of O2 consumption
against
, exercise endurance times and
during recovery from vigorous exercise were measured inSceloporus occidentalis captured near sea level and inS. graciosus captured above 2850 m. Oxygen consumption against
was also measured inS. occidentalis captured above 2850 m. When
was recorded continuously, as ambient
was slowly reduced from 155 Torr, it became directly dependent upon ambient
between 110 and 120 Torr. The critical
for the high altitude lizards was lower than that for the lowland lizards, which enabled the former to maintain relatively higher
's when ambient
was reduced below 120 Torr. The high altitude lizards also had significantly greater endurance when stimulated to exercise at 1600 m (
130 Torr). Both the higher
under hypoxia and the greater endurance roughly parallel a significantly greater maximum
in the high altitude lizards. At a simulated altitude of 3600 m (
100 Torr), maximum
and rate of recovery of the O2 debt calculated from post active
were significantly reduced in the lowland but not the high altitude lizards. The effects of simulated altitude conditions on the lowland but not the mountaine animals indicate adaptations to altitude in these sceloporine lizards. We did not find any consistent relationship between organ/body weight ratios or hematocrit and our measures of
endurance or the altitude at which the lizards were captured. 相似文献
2.
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
3.
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
4.
Linkage analysis using multiple DNA polymorphic markers in normal families and in families with fragile X syndrome 总被引:4,自引:1,他引:3
S. N. Thibodeau H. R. Dorkins K. R. Faulk R. Berry A. C. M. Smith R. Hagerman A. King K. E. Davies 《Human genetics》1988,79(3):219-227
Summary Linkage data, using the polymorphic markers 52A (DXS51), F9, 4D-8(DXS98), and St14(DXS52), are presented from 14 fragile X pedigrees and from 7 normal pedigrees derived from the collection of the Centre d'Étude du Polymorphisme Humaine. A multipoint linkage analysis indicates that the most probable order of these four loci in normal families is DXS51-F9-DXS98-DXS52. Recombination frequencies (
) corresponding to maximum LOD scores (
) were obtained by two-point linkage analysis for a nuber of linkage groups, including: DXS51-F9 (
=5.94,
=0.03), F9-DXS98 (
=0.51,
=0.26), F9-DXS52 (
=0.84,
=0.27), and DXS98-DXS52 (
=0.32,
=0.20). A multipoint linkage analysis of these loci, including the fragile X locus, was also performed for the fragile X population and the data support the relative order (DSX51, F9, DXS98)-FRAXA-DXS52. Recombination frequencies and maximum LOD scores, which again were derived from two-point linkage analyses, were obtained for the linkage groups DXS51-F9 (
=9.96,
=0) and F9-DXS52 (
=0.07,
=0.45), as well as for the groups DXS51-FRAXA (
=2.42,
=0.15), F9-FRAXA (
=1.30,
=0.18), DXS98-FRAXA (
=0.05
=0.36), and DXS52-FRAXA (
=2.42
=0.15). The linkage data was further tested for the presence of genetic heterogeneity both within and between the fragile X and normal families for the intervals DXS51-F9, F9-DXS52, F9-FRAXA, and DXS52-FRAXA using a modification of the A test. Except for the interval F9-FRAXA (P<0.10) there was no evidence of genetic heterogeneity for each of the various linkage groups examined. The heterogeneity detected for the interval F9-FRAXA, however, was most likely due to one family (Fx-28) that displayed very tight linkage between these two loci. 相似文献
5.
Sheroziya O. P. Ermishkin V. V. Lukoshkova E. V. Mazygula E. P. Ryb'yakova V. B. Chepetova T. V. 《Neurophysiology》2003,35(6):434-444
In 19 tested persons in the resting lying position, we examined changes in the mean duration of R-R intervals
and in parasympathetic chronotropic cardiac reactions (respiratory arrhythmia,RA, and swallowing-related tachycardia, ST) induced by intensified tonic parasympathetic influences after peroral administration of antagonists of muscarinic (M) receptors in small doses. Administration of 0.02 g of an extract of Belladonna, which contains alkaloids of the atropine group, led to a significant
increase (P < 0.001). In this case, the RA at the natural frequency of breathing (P < 0.05) and ST (P < 0.001) simultaneously increased. Close correlation was observed both between initial values of the ST and
in various tested persons (r = 0.87) and between changes in these values, which were induced by the action of small amounts of M antagonists (r = 84). In various persons, the RA during deep slowed breathing (6 min-1, RA6) demonstrated ambiguous modifications. In the structure of RA6, we identified two components: an inspiratory tachycardic (TC) and an expiratory bradycardic (BC). With intensification of the parasympathetic influences, the TC began to prevail; its increase was strongly related to a rise in the
(r = 0.84). In contrast, correlation between changes in the BC and an increase in the
was completely absent (r = 0.001). Therefore, small amounts of M antagonists intensify both the tonic component of parasympathetic control (increasing the
) and its dynamic indices, the magnitudes of the ST and RA. Tachycardia during swallowing and the inspiratory TC under conditions of deep slowed breathing are closely related to changes in the parasympathetic influences. The magnitude of the RA is the index, which reflects the tonic component of chtonotropic control under conditions of both slowed and natural breathing less adequately than the ST. 相似文献
6.
B. Grubb G. E. Folk Jr. 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1978,128(2):185-188
Summary The rate of oxygen consumption (
) by skeletal muscle was investigated in isolated perfused hindlimbs of laboratory rats and lemmings (Lemmus). In both species,
increased in proportion to blood flow rate, even at flow rates 4–5 times above resting level. The slope of the line relating
to skeletal muscle blood flow was significantly greater in the lemming than in the rat. This may be related to the inverse relationship between body weight and metabolic rate. These data support the hypothesis that in small animals a dependent relationship exists between blood flow and skeletal muscle
. 相似文献
7.
We determined the rate of oxygen consumption in the White Sea edible mussel Mytilus edulis of different ages. The mass-specific rate of oxygen consumption proved to decrease with mussel age according to the equation:
= 40.1/(1 – e
–0.194t
), where
is mass-specific rate of oxygen consumption and t is age. Allometric coefficients of the oxygen consumption rate–soft tissue weight relationship were also determined. 相似文献
8.
Didier G. Arqués Jean-Paul Fallot Christian J. Michel 《Bulletin of mathematical biology》1998,60(1):163-194
The self-complementary subset
∪{AAA,TTT} with
= {AAC, AAT, ACC, ATC, ATT, CAG, CTC, CTG, GAA, GAC, GAG, GAT, GCC, GGC, GGT, GTA, GTC, GTT, TAC, TTC} of 22 trinucleotides
has a preferential occurrence in the frame 0 (reading frame established by the ATG start trinucleotide) of protein (coding)
genes of both prokaryotes and eukaryotes. The subsets
∪{CCC} and
∪{GGG} of 21 trinucleotides have a preferential occurrence in the shifted frames 1 and 2 respectively (frame 0 shifted by
one and two nucleotides respectively in the 5′-3′ direction).
and
are complementary to each other. The subset
contains the subset
which has the rarity property (6 × 10−8) to be a complementary maximal circular code with two permutated maximal circular codes
and
in the frames 1 and 2 respectively.
is called a C3 code.
A quantitative study of these three subsets
in the three frames 0, 1, 2 of protein genes, and the 5′ and 3′ regions of eukaryotes, shows that their occurrence frequencies
are constant functions of the trinucleotide positions in the sequences. The frequencies of
in the frame 0 of protein genes are 49, 28.5 and 22.5% respectively. In contrast, the frequencies of
in the 5′ and 3′ regions of eukaryotes, are independent of the frame. Indeed, the frequency of
in the three frames of 5′ (respectively 3′) regions is equal to 35.5% (respectively 38%) and is greater than the frequencies
and
, both equal to 32.25% (respectively 31%) in the three frames.
Several frequency asymmetries unexpectedly observed (e.g. the frequency difference between
and
in the frame 0), are related to a new property of the subset
involving substitutions. An evolutionary analytical model at three parameters (p, q, t) based on an independent mixing of the 22 codons (trinucleotides in frame 0) of
with equiprobability (1/22) followed by t ≈ 4 substitutions per codon according to the proportions p ≈ 0.1; q ≈ 0.1 and r = 1 − p − q ≈ 0.8 in the three codon sites respectively, retrieves the frequencies of
observed in the three frames of protein genes and explains these asymmetries. Furthermore, the same model (0.1, 0.1, t) after t ≈ 22 substitutions per codon, retrieves the statistical properties observed in the three frames of the 5′ and 3′ regions.
The complex behaviour of these analytical curves is totally unexpected and a priori difficult to imagine. 相似文献
9.
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
10.
Stephen C. Wood Kjell Johansen Mogens L. Glass G. M. O. Maloiy 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1978,127(4):331-336
Summary Oxygen consumption
was measured at rest and during spontaneous activity at body temperatures of 25 and 35°C in 14 fasting Savanna monitor lizards,Varanus exanthematicus ranging in weight from 172 to 7500 g. The allometric relationship between metabolic rate at 25°C and body weight (W) is given by:
(ml O2 STPD·g–1·hr–1)=0.88W
–0.43 (Fig. 2). Although statistical comparisons are equivocal, this intraspecific size dependence exceeds that reported for interspecific comparisons among reptiles and other vertebrate groups (Fig 3). A reproducible diurnal pattern of activity was observed in undisturbed animals with minimum values of
between 2400 and 0800 h (Fig. 1). Spontaneous activity and
generally reached peak values between 1200 and 2000 hrs. The average ratio of active aerobic metabolic rate (AMR) to minimum (standard) aerobic metabolic rate (SMR) was 8.2. This voluntary AMR/SMR inVaranus exceeds the AMR/SMR for most reptiles stimulated to exhaustion. The high aerobic capacity is consistent with other evidence for efficient exchange and transport of respiratory gases inV. exanthematicus; e.g., low or absent intracardiac shunt flow resulting in high arterial saturation and low ventilation
and perfusion
requirements. 相似文献
11.
An analytical model is developed to describe the performance of a packed-bed immobilized enzyme reactor in which parallel processes take place. In particular, two-substrate reaction, inhibition of the enzyme by one of the reaction products, and binding of one substrate and/or one product to an added ligand are taken into account. In addition, substrates and product diffusion into the porous catalyst are also considered. Using this model, numerical simulations were performed. The results point to the fact that, when all the above processes occur concomitantly, a variety of performance characteristics can be obtained, depending on the particular values of the related parameters. Moreover, under certain conditions, the reactor performance can be improved by controlled addition of ligand.List of Symbols
A
total concentration of ligand
-
C
1,i
concentration of Substrate-1 in the pores of stage i
-
C
2,i
concentration of Substrate-2 in its free form in the pores of stage i
-
2,i
concentration of the Substrate-2-Ligand Complex in the pores of stage i
-
total concentration of Substrate-2 in the pores of stage i
-
i
concentration of the Product-Ligand Complex in the pores of stage i
-
concentration of the free Product in the pores of stage i
-
total concentration of the Product in the pores of stage i
-
internal (pore) diffusion coefficient for the Substrate-Ligand Complex
-
D
1
internal (pore) diffusion coefficient of Substrate-1
-
D
2
internal (pore) diffusion coefficient of Substrate-2
-
effective (pore) diffusion coefficient for Substrate-2
-
internal (pore) diffusion coefficient for the Product
-
internal (pore) diffusion coefficient for the Product-Ligand Complex
-
effective (pore) diffusion coefficient for the Product
-
K
thermodynamic equilibrium constant for binding Substrate-2 to Ligand
-
K
m,1,K
m,2
Michaelis constants for Substrates-1 and 2, respectively
-
effective Michaelis constant for Substrate-2
-
K
p
thermodynamic equilibrium constant for binding the reaction Product to Ligand
-
effective equilibrium constant for binding Substrate-2 to Ligand
-
effective equilibrium constant for binding the reaction Product to Ligand.
-
K
b
inhibition constant
-
K
q
inhibition constant
-
effective inhibition constant
-
effective inhibition constant
-
k
a, k
d
association and dissociation rate constants for Substrate-2 — Ligand complex
-
association and dissociation constants for Product —Ligand complex
-
n
total number of elementary stages in the reactor
-
Q
volumetric flow rate throughout the reactor
-
R
j,i
reaction rate of Substrate-j in stage i, in terms of volumetric units
-
S
1,0
concentration of Substrate-1 in the reactor feed
-
total concentration of Substrate-2 in the reactor feed
-
S
1,i–1,S
1,i
concentration of Substrate-1 in the bulk phase leaving stages i–1 and i, respectively
-
S
2,i
concentration of Substrate-2 in its free form, in the bulk phase leaving stage i
-
2,i–1,
2,i
concentration of Substrate-2 in the bulk phase leaving stage i–1 and i, respectively
-
total concentration of Substrate-2 in the bulk phase leaving stages i–1 and i, respectively
-
i
concentration of the Product-Ligand Complex in the bulk phase of stage i
-
concentration of free Product in the bulk phase of stage i
-
total concentration of Product in the bulk phase of stage i
-
V
total volume of the reactor
-
V
m
maximal reaction rate in terms of volumetric units
-
y
axial coordinate of the pores
-
y
0
depth of the pores
Greek Symbols
1
dimensionless parameter
-
dimensionless parameter
-
dimensionless parameter
-
1
dimensionless parameter
-
dimensionless parameter
-
1,i
dimensionless concentration of Substrate-1 in pores of stage i
-
dimensionless total concentration of Substrate-2 (in both free and bound form) in pores of stage i
-
dimensionless total concentration of the reaction product in the pores of stage i
-
1
dimensionless parameter
-
dimensionless parameter
-
dimensionless parameter
-
dimensionless parameter
-
dimensionless parameter
-
dimensionless position along the pore
-
volumetric packing density of catalytic particles (dimensionless)
-
porosity of the catalytic particles (dimensionless)
-
1,i
dimensionless concentration of Substrate-1 in the bulk phase of stage i
-
dimensionless total concentration of Substrate-2 (in both free and bound form) in the bulk phase of stage i 相似文献
12.
Ivona Aksentijevich Luis Gruberg Elon Pras James E. Balow Jr. Michal Kovo Ephraim Gazit Michael Dean Mordechai Pras Daniel L. Kastner 《Human genetics》1993,91(6):527-534
Familial Mediterranean fever (FMF) is an autosomal recessive disorder of unknown pathogenesis, characterized by recurrent, selflimited attacks of fever with synovitis, peritonitis, or pleurisy. Using DNAs from affected Israeli families, we have recently mapped the gene causing FMF (designated MEF) to the short arm of chromosome 16, with two-point lod scores in excess of 20. In this report we consider the possibility of a second FMF susceptibility locus. Before discovering linkage to markers on chromosome 16, we had found suggestive evidence for linkage to chromosome 17q, with the following maximal two-point lod scores: D17S74 (pCMM86),
= 2.47, (
= 0.20); D17S40 (pLEW101),
= 2.15(
= 0.15); D17S35 (CRI-pP3-1),
= 1.78 (
= 0.15); D17S46 (pLEW108),
= 1.69 (
= 0.18), D17S254,
= 2.30 (
= 0.20). Moreover, multipoint linkage analysis using D17S74 and D17S40 as fixed loci gave
= 3.27 approximately 10 centimorgans (cM) telomeric to D17S40. Data with the chromosome 17 markers alone in our families suggested locus heterogeneity. Nevertheless, our families were not separable into complementary subsets showing linkage either to chromosome 16 or to chromosome 17. We also examined the possibility that the positive lod scores for chromosome 17 might reflect a secondary, modifying locus. By several measures of disease severity, families with positive lod scores for chromosome 17 loci had no worse disease than those with negative lod scores for these loci. We conclude that chromosome 17 does not encode a major FMF susceptibility gene for some of the families, nor does it encode a disease-modifying gene. Rather, it would appear that linkage to chromosome 17 is a false positive (type I) error. These results reemphasize the fact that a lod score of 3.0 corresponds to a posterior probability of linkage of 95%, with an attendant 1 in 20 chance of observing a false positive. 相似文献
13.
T. B. R. J. Smith W. G. Hopkins N. A. S. Taylor 《European journal of applied physiology and occupational physiology》1994,69(1):44-49
The position of the body and use of the respiratory muscles in the act of rowing may limit ventilation and thereby reduce maximal aerobic power relative to that achieved in cycling or running, in spite of the greater muscle mass involved in rowing. This hypothesis was investigated for three groups of male subjects: nine elite senior oarsmen, eight former senior oarsmen and eight highly trained athletes unskilled in rowing. The subjects performed graded exercise to maximal effort on a rowing ergometer, cycle ergometer and treadmill while respiratory minute volume
and oxygen consumption
were monitored continuously. The VE at a given
during intense submaximal exercise (greater than 75% of maximal
) was not significantly lower in rowing compared with that in cycling and treadmill running for any group, which would suggest that submaximal rowing does not restrict ventilation. At maximal effort,
and
for rowing were less than those for the other types of exercise in all the groups, although the differences were not statistically significant in the elite oarsmen. These data are consistent with a ventilatory limitation to maximal performance in rowing that may have been partly overcome by training in the elite oarsmen. Alternatively, a lower maximal VE in rowing might have been an effect rather than a cause of a lower maximal
if maximal
was limited by the lower rate of muscle activation in rowing. 相似文献
14.
Anne-Spence M. Falk Catherine T. Neiswanger Katherine Leigh Field L. Marazita Mary L. Allen F. H. Siervogel Roger M. Roche Alex F. Crandall Barbara F. Sparkes Robert S. 《Human genetics》1984,67(2):183-186
Summary Two data sets are analyzed for linkage between the PTC and Kell blood group loci. The original report of close linkage for these loci was that of Conneally et al. (1976), where the maximum likelihood estimate of was 0.05. These two new data sets give a combined maximum likelihood estimate of
m=f
=0.28. Estimating the recombination frequency for the sexes separately gave
m
=0.29,
f
=0.23. The combined maximum likelihood estimate over all published data sets including this report is
m=f
=0.14,
max=8.94. There is statistically significant evidence of heterogeneity among the published studies. 相似文献
15.
Chronic nitrate additions dramatically increase the export of carbon and nitrogen from northern hardwood ecosystems 总被引:22,自引:4,他引:18
Kurt S. Pregitzer Donald R. Zak Andrew J. Burton Jennifer A. Ashby Neil W. MacDonald 《Biogeochemistry》2004,68(2):179-197
A long-term field experiment was initiated to simulate chronic atmospheric N deposition, a widespread phenomenon in industrial regions of the world. Eight years of experimental nitrate (
) additions (3 g
-N m–2 per year) to four different northern hardwood forests located along a 500 km geographic gradient dramatically increased leaching losses of
-N, dissolved organic carbon (DOC), and dissolved organic nitrogen (DON). During the last two water years, the average increase in solution
-N and DON leaching from the
-amended plots was 2.2 g N m–2, equivalent to 72% of the annual experimental N addition. Results indicate that atmospheric N deposition may rapidly saturate some northern hardwood ecosystems across an entire biome in the upper Great Lakes Region of the USA. Changes in soil C and N cycling induced by chronic N deposition have the potential in this landscape to significantly alter the flux of DOC and DON from upland to aquatic ecosystems. Michigan Gradient study site characteristics are similar to those of European forests most susceptible to N saturation. 相似文献
16.
Canadian populations of D. radicum differ in their response to temperature during postdiapause development. Populations that are primarily of the early-emerging type (
) (St-Jean, Quebec; London, Ontario) have high values for the parameters describing this response: % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamOuamaaBa% aaleaacaWGTbaabeaakiabg2da9aaa!38F2!$$R_m = $$ 12.7–13.3;
28.0–31.8 °C ; T = 10.3–14.2 (
, the maximum developmental rate at the temperature,
[ °C ] where the developmental rate is highest, and T , the parameter which gives the shape of the truncated normal curve fitted to the data), a low degree-day requirement for emergence (160–232
), and may lack a developmental delay at temperatures above ca. 21 °C . Populations of the late-emerging type (Kildare, Prince Edward Island) have low parameter values (
,
°C ; T = 6.4), high degree-day requirements (530
), and a developmental delay at high temperatures. The parameters for the early-emergers in the population from Winnipeg, Manitoba (74% early) were intermediate (
,
°C , T = 10.7,
), but resembled the early rather than the late type. This population varied from 31 to 90% early type over a 10-year period and the rate of postdiapause development at 20 °C was directly related to the percentage early. In the year with the most rapid development (90% early), development was significantly slower than in the populations from other locations with predominantly early populations, and the year with the slowest development (31% early) showed significantly faster development than that from Kildare, Prince Edward Island (100% late). Therefore the parameters for early and late types of development will not be accurate for use in mixed populations, and the parameters in mixed populations will change among years. Populations of D. radicum in North America and Europe (67 locations by years) varied from 0–100% early. At Winnipeg, the percentage early was directly related to the annual temperature accumulation (
) during the growing season. The calculation of developmental parameters for the early-emergers of mixed populations provides a more accurate basis for estimating the times of first emergence and the first peak of emergence than parameters based on the whole population. Since postdiapause developmental rates vary both among and annually within locations, developmental models should be designed to include such variations. 相似文献
17.
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
18.
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
19.
Summary
D. melanogaster males of
bb/O genetic constitution undergoing rDNA magnification were mated singly to XXbb
+/O females, yielding
bb/O male progeny, and to XNO-w sn bb
+ fameles, yielding
bb/XNO- females. The male and female offspring were scored for the bb
+ phenotype.Results show that there is a higher percentage of bb
+ flies in the
bb/O male progeny than in
bb/XNO- females progeny, in single crosses as well as in the combined data. rRNA/DNA hybridization experiments agree with this observation, by showing that the rDNA content in the progeny of premagnified flies was higher in the sons than in the daughters.These data indicate that the increase of ribosomal RNA genes is not due to a stable event such as an unequal mitotic sister exchange, whereas they do not contrast with the extracopy model. 相似文献
20.
Henrik Laasch 《Planta》1989,178(4):553-560
A series of tertiary amines was investigated for effects on the transmembrane proton potential difference (
H), on photophosphorylation and on electron-flux control related to the intrathylakoid proton potential (
HI), using isolated chloroplasts ofSpinacia oleracea L. As indicated by 9-aminoacridine fluorescence and [14C]methylamine uptake, all amines studied inhibited a build-up of
H and, in parallel, ATP synthesis. Even when
H was low, strong
H1-dependent electron-flux control was observed under the influence of tertiary amines. The strength of flux control in the presence of low
H and the effectiveness of inhibition of ATP synthesis linearly increased with the lipophilicity of the amines. The most effective of the amines tested caused 50% inhibition of ATP synthesis at a concentration of 6 M, which is about 1000-fold lower than the concentration required for inhibition by methylamine. The data presented indicate the existence of two proton domains in the thylakoid vesicles, one of them feeding the ATP-synthase, the other the sites of pH-dependent electron-flux control. It is concluded that tertiary amines develop their action in a lipophilic domain of the thylakoid membrane, in the vicinity of the ATP-synthase complex. A mechanism for selective uncoupling and for the maintenance of
HI-dependent electron flux control in the presence of low
H is discussed.Abbreviations and symbols
coefficient for pH-dependent electron flux control
- 9-AA
9-aminoacridine
- Chl
chlorophyll
- I50
amine concentration producing 50% inhibition of ATP-synthesis
- Je
flux of photosynthetic electron transport
-
k
H
apparent rate constant for proton efflux
-
H1
proton potential in the thylakoid lumen
-
H1
transthylakoid proton potential difference
-
p
partition coefficient
-
q
AA
coefficient for 9-aminoacridine fluorescence quenching
- PS
photosystem
- Q
quantum flux of photosynthetically active light
Dedicated to Professor Wilhelm Simonis, on the occasion of his 80th birthday 相似文献