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1.
Maximum sustained swimming speeds, swimming energetics and swimming kinematics were measured in the green jack Caranx caballus (Teleostei: Carangidae) using a 41 l temperature‐controlled, Brett‐type swimming‐tunnel respirometer. In individual C. caballus [mean ±s.d. of 22·1 ± 2·2 cm fork length (LF), 190 ± 61 g, n = 11] at 27·2 ± 0·7° C, mean critical speed (Ucrit) was 102·5 ± 13·7 cm s?1 or 4·6 ± 0·9 LF s?1. The maximum speed that was maintained for a 30 min period while swimming steadily using the slow, oxidative locomotor muscle (Umax,c) was 99·4 ± 14·4 cm s?1 or 4·5 ± 0·9 LF s?1. Oxygen consumption rate (M in mg O2 min?1) increased with swimming speed and with fish mass, but mass‐specific M (mg O2 kg?1 h?1) as a function of relative speed (LF s?1) did not vary significantly with fish size. Mean standard metabolic rate (RS) was 170 ± 38 mg O2 kg?1 h?1, and the mean ratio of M at Umax,c to RS, an estimate of factorial aerobic scope, was 3·6 ± 1·0. The optimal speed (Uopt), at which the gross cost of transport was a minimum of 2·14 J kg?1 m?1, was 3·8 LF s?1. In a subset of the fish studied (19·7–22·7 cm LF, 106–164 g, n = 5), the swimming kinematic variables of tailbeat frequency, yaw and stride length all increased significantly with swimming speed but not fish size, whereas tailbeat amplitude varied significantly with speed, fish mass and LF. The mean propulsive wavelength was 86·7 ± 5·6 %LF or 73·7 ± 5·2 %LT. Mean ±s.d . yaw and tailbeat amplitude values, calculated from lateral displacement of each intervertebral joint during a complete tailbeat cycle in three C. caballus (19·7, 21·6 and 22·7 cm LF; 23·4, 25·3 and 26·4 cm LT), were 4·6 ± 0·1 and 17·1 ± 2·2 %LT, respectively. Overall, the sustained swimming performance, energetics, kinematics, lateral displacement and intervertebral bending angles measured in C. caballus were similar to those of other active ectothermic fishes that have been studied, and C. caballus was more similar to the chub mackerel Scomber japonicus than to the kawakawa tuna Euthynnus affinis. 相似文献
2.
This study provides the first measurements of the standard respiration rate (RS) and growth dynamics of European sardine Sardina pilchardus larvae reared in the laboratory. At 15° C, the relationship between RS (µl O2 individual?1 h?1) and larval dry mass (MD, µg) was equal to: RS = 0·0057(±0·0007, ± s.e.)·MD0·8835(±0·0268), (8–11% MD day?1). Interindividual differences in RS were not related to interindividual differences in growth rate or somatic (Fulton's condition factor) or biochemical‐based condition (RNA:DNA). 相似文献
3.
Key components of swimming metabolism: standard metabolism (Rs), active metabolism (Ra) and absolute aerobic scope for activity (Ra–Rs) were determined for small age 0 year Atlantic cod Gadus morhua. Gadus morhua juveniles grew from 0·50 to 2·89 g wet body mass (MWB) over the experimental period of 100 days, and growth rates (G) ranged from 1·4 to 2·9% day?1, which decreased with increasing size. Metabolic rates were recorded by measuring changes in oxygen consumption over time at different activity levels using modified Brett‐type respirometers designed to accommodate the small size and short swimming endurance of small fishes. Power performance relationships were established between oxygen consumption and swimming speed measurements were repeated for individual fish as each fish grew. Mass‐specific standard metabolic rates () were calculated from the power performance relationships by extrapolating to zero swimming speed and decreased from 7·00 to 5·77 μmol O2 g?1 h?1, mass‐specific active metabolic rates () were calculated from extrapolation to maximum swimming speed (Umax) and decreased from 26·18 to 14·35 μmol O2 g?1 h?1 and mass‐specific absolute scope for activity was calculated as the difference between active and standard metabolism () and decreased from 26·18 to 14·35 μmol O2 g?1 h?1 as MWB increased. Small fish with low Rs had bigger aerobic scopes but, as expected, Rs was higher in smaller fish than larger fish. The measurements and results from this study are unique as Rs, Ra and absolute aerobic scopes have not been previously determined for small age 0 year G. morhua. 相似文献
4.
The cyanobacterium Synechococcus R-2 (Anacystis nidulans, S. leopoliensis) PCC 7942 has a sodium-dependent chloride transporter 总被引:1,自引:1,他引:0
R. J. RITCHIE 《Plant, cell & environment》1992,15(2):163-177
Synechococcus R-2 (PCC 7942) actively accumulated Cl? in the light and dark, under control conditions (BG-11 media: pHo, 7·5; [Na+]o, 18 mol m?3; [Cl?]o, 0·508 molm?3). In BG-11 medium [Cl?], was 17·2±0·848 mol m?3 (light), electrochemical potential of Cl? (ΔμCl?i,o) =+211±2mV; [Cl?]i= 1·24±0·11 mol m?3(dark), ΔμCl?i,o=+133±4mV. Cl? fluxes, but not permeabilities, were much higher in the light: ?Cl?i,o= 4·01±5·4 nmol m?2 s?1, PCl?i,o= 47±5pm s?1 (light); ?Cl?i,o= 0·395±0·071 nmol m?2 s?1, PCl?i,o= 69±14 pm s?1 (dark). Chloride fluxes are inhibited by acid pHo (pHo 5; ?Cl?i,o= 0·14±0·04 nmol m?2 s?1); optimal at pHo 7·5 and not strongly inhibited by alkaline pHo (pHo 10; ?Cl?1i,o= 1·7±0·14 nmol m?2 s?1). A Cl?in/2H+in coporter could not account for the accumulation of Cl? alkaline pHo. Permeability of Cl? is very low, below 100pm s?1 under all conditions used, and appears to be maximal at pHo 7·5 (50–70 pm s?1) and minimal in acid pHo (20pm s?1). DCCD (dicyclohexyl-carbodiimide) inhibited ?Cl?i,o in the light about 75% and [Cl?]i fell to 2·2±0·26 (4) mol m?3. Valinomycin had no effect but monensin severely inhibited Cl? uptake ([Cl?]i= 1·02±0·32 mol m?3; ?Cl?i,o= 0·20±0·1 nmol m?2 s?1). Vanadate (200 mmol m?3) accelerated the Cl? flux (?Cl?i,o= 5·28±0·64 nmol m?2 s?1) but slightly decreased accumulation of Cl? ([Cl?], = 13·9±1·3 mol m?3) in BG-11 medium but had no significant effect in Na+-free media. DCMU (dichlorophenyldimethylurea) did not reduce [Cl?], or ?Cl?i,o to that found in the dark ([Cl?]i= 8·41±0·76 mol m?3; ?Cl?i,o= 2·06±0·36 nmol m?2 s?1). Synechococcus also actively accumulated Cl? in Na+-free media, [Cl?]i was lower but ΔΨi,o hyperpolarized in Na+-free media and so the ΔμCl?i,o was little changed ([Cl?]i= 7·98±0·698 mol m?3; ΔμCl?i,o=+203±3 mV). Net Cl? uptake was stimulated by Na+; Li+ acted as a partial analogue for Na+. Synechococcus has a Na+ activated Cl? transporter which is probably a primary 2Cl?/ATP pump. The Cl? pump is voltage sensitive. ΔμCl?i,o is directly proportional to ΔΨi,o(P»0·01%): ΔμCl?i,o= -1·487 (±0·102) ×ΔΨi,o, r= -0·983, n= 31. The ΔμCl?i,o increased (more positive) as the Δμi,o became more negative. The ΔμCl?i,o has no known function, but might provide a driving force for the uptake of micronutrients. 相似文献
5.
Heart rate as an indicator of metabolic rate and activity in adult Atlantic salmon, Salmo salar 总被引:1,自引:0,他引:1
M. C. Lucas 《Journal of fish biology》1994,44(5):889-903
Telemetered heart rate (fH) was examined as an indicator of activity and oxygen consumption rate (VO2) in adult, cultivated, Atlantic salmon, Salmo salar L. Heart rate was measured during sustained swimming in a flume for six fish at 10° C [mean weight, 1114 g; mean fork length (f. l.), 50·6 cm] and seven fish at 15° C (mean weight, 1119 g; mean f. l., 50·7 cm) at speeds of up to 2·2 body lengths/s. Semi–logarithmic relationships between heart rate and swimming speed were obtained at both temperatures. Spontaneously swimming fish in still water exhibited characteristic heart rate increases associated with activity. Heart rate and Vo2 were monitored simultaneously in a 575–1 circular respirometer for six fish (three male, three female) at 4° C (mean weight, 1804 g; mean F. L., 62· cm) and six fish (three male, three female) at 10° C (mean weight, 2045 g; mean f. l., 63·2 cm) during spontaneous but unquantified activity. Linear regressions were obtained by transforming data for both fH and Vo2 to log values. At each temperature, slopes of the regressions between fH and Vo2 for individual fishes were not significantly different, but in some cases elevations were. All differences in elevation were between male and female fish. There were no significant differences in regression slope or elevation for fish of the same sex at the two temperatures and so regressions were calculated for the sexes, pooling data from 4 and 10° C. There was no significant difference in the mean ± S. D. Vo2 between the sexes at 4° C (male, 66·0 ± 59·6 mgO2 kg?1 h?1; female, 88·0 ± 60·1 mgO2 kg?1 h?1) or 10° C (male, 166·2 ± 115·4 mgO2 kg?1 h?1; female, 169·2 ± 111–1 mgO2 kg?1h?1). Resting Vo2 (x?± s. d.) at 4°C was 36·7 ± 8.4 mgO2 kg?1 h?1, and 10° C was 72·8 ± 11·9 mgO2 kg?1 h?1. Maximum Vo2 (x?± S. D.) at 4° C was 250·6 ± 40·2 mgO2 kg?1 h?1, and at 10° C was 423·6 ± 25·2 mgO2 kg?1 h?1. Heart rate appears to be a useful indicator of metabolic rate over the temperature range examined, for the cultivated fish studied, but it is possible that the relationship for wild fish may differ. 相似文献
6.
M. M. Mazur †‡ M. T. Wilson † A. B. Dougherty † A. Buchheister † D. A. Beauchamp § 《Journal of fish biology》2007,70(3):816-836
A bioenergetics model for juvenile age‐0 year walleye pollock Theragra chalcogramma was applied to a spatially distinct grid of samples in the western Gulf of Alaska to investigate the influence of temperature and prey quality on size‐specific growth. Daily growth estimates for 50, 70 and 90 mm standard length (LS) walleye pollock during September 2000 were generated using the bioenergetics model with a fixed ration size. Similarities in independent estimates of prey consumption generated from the bioenergetics model and a gastric evacuation model corroborated the performance of the bioenergetics model, concordance correlation (rc) = 0·945, lower 95% CL (transformed) (L1) = 0·834, upper 95% CL (transformed) (L2) = 0·982, P < 0·001. A mean squared error analysis (MSE) was also used to partition the sources of error between both model estimates of consumption into a mean component (MC), slope component (SC), and random component (RC). Differences between estimates of daily consumption were largely due to differences in the means of estimates (MC= 0·45) and random sources (RC= 0·49) of error, and not differences in slopes (SC= 0·06). Similarly, daily growth estimates of 0·031–0·167 g day?1 generated from the bioenergetics model was within the range of growth estimates of 0·026–0·190 g day?1 obtained from otolith analysis of juvenile walleye pollock. Temperature and prey quality alone accounted for 66% of the observed variation between bioenergetics and otolith growth estimates across all sizes of juvenile walleye pollock. These results suggest that the bioenergetics model for juvenile walleye pollock is a useful tool for evaluating the influence of spatially variable habitat conditions on the growth potential of juvenile walleye pollock. 相似文献
7.
Uptake kinetics and storage capacity of dissolved inorganic phosphorus and corresponding N:P dynamics in Ulva lactuca (Chlorophyta)
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Dissolved inorganic phosphorus (DIP ) is an essential macronutrient for maintaining metabolism and growth in autotrophs. Little is known about DIP uptake kinetics and internal P‐storage capacity in seaweeds, such as Ulva lactuca (Chlorophyta). Ulva lactuca is a promising candidate for biofiltration purposes and mass commercial cultivation. We exposed U. lactuca to a wide range of DIP concentrations (1–50 μmol · L?1) and a nonlimiting concentration of dissolved inorganic nitrogen (DIN ; 5,000 μmol · L?1) under fully controlled laboratory conditions in a “pulse‐and‐chase” assay over 10 d. Uptake kinetics were standardized per surface area of U. lactuca fronds. Two phases of responses to DIP ‐pulses were measured: (i) a surge uptake (VS ) of 0.67 ± 0.10 μmol · cm?2 · d?1 and (ii) a steady state uptake (VM ) of 0.07 ± 0.03 μmol · cm?2 · d?1. Mean internal storage capacity (ISCP ) of 0.73 ± 0.13 μmol · cm?2 was calculated for DIP . DIP uptake did not affect DIN uptake. Parameters of DIN uptake were also calculated: VS = 12.54 ± 1.90 μmol · cm?2 · d?1, VM = 2.26 ± 0.86 μmol · cm?2 · d?1, and ISCN = 22.90 ± 6.99 μmol · cm?2. Combining ISC and VM values of P and N, nutrient storage capacity of U. lactuca was estimated to be sufficient for ~10 d. Both P and N storage capacities were filled within 2 d when exposed to saturating nutrient concentrations, and uptake rates declined thereafter at 90% for DIP and at 80% for DIN . Our results contribute to understanding the ecological aspects of nutrient uptake kinetics in U. lactuca and quantitatively evaluating its potential for bioremediation and/or biomass production for food, feed, and energy. 相似文献
8.
R. J. RITCHIE 《Plant, cell & environment》1992,15(2):179-184
The kinetics of the light-driven Cl? uptake pump of Synechococcus R-2 (PCC 7942) were investigated. The kinetics of Cl? uptake were measured in BG-11 medium (pHo, 7·5; [K+]o, 0·35 mol m?3; [Na+]o, 18 mol m?3; [Cl?]o, 0·508 mol m?3) or modified media based on the above. Net36Cl? fluxes (?Cl?o,i) followed Michaelis-Menten kinetics and were stimulated by Na+ [18 mol m?3 Na+ BG-11 ?Cl?max= 3·29±0·60 (49) nmol m?2 s?1 versus Na+-free BG-11 ?Cl?max= 1·02±0·13 (54) nmol m?2 s?1] but the Km was not significantly different in the presence or absence of Na+ at pHo 10; the Km was lower, but not affected by the presence or absence of Na+ [Km = 22·3±3·54 (20) mmol m?3]. Na+ is a non-competitive activator of net ?Cl?o,i. High [K+]o (18 mol m?3) did not stimulate net ?Cl?o,i or change the Km in Na+-free medium. High [K+]o (18 mol m?3) added to Na+ BG-11 medium decreased net ?Cl?o,i [18 mol m?3K+ BG-11; ?Cl?max= 2·50±0·32 (20) nmol m?2 s?1 versus BG-11 medium; ?Cl?max= 3·35±0·56 (20) nmol m?2 s?1] but did not affect the Km 55·8±8·100 (40) mmol m?3]. Na+-stimulation of net ?Cl?o,i followed Michaelis-Menten kinetics up to 2–5 mol m?3 [Na+]o but higher concentrations were inhibitory. The Km for Na+-stimulation of net ?Cl?o,i [K1/2(Na+)] was different at 47 mmol m?3 [Cl?]o (K1/2[Na+] = 123±27 (37) mmol m?3]. Li+ was only about one-third as effective as Na+ in stimulating Cl? uptake but the activation constant was similar [K1/2(Li+) = 88±46 (16) mmol m?3]. Br? was a competitive inhibitor of Cl? uptake. The inhibition constant (Ki) was not significantly different in the presence and absence of Na+. The overall Ki was 297±23 (45) mmol m?3. The discrimination ratio of Cl? over Br? (δCl?/δBr?) was 6·38±0·92 (df = 147). Synechococcus has a single Na+-stimulated Cl? pump because the Km of the Cl? transporter and its discrimination between Cl? and Br? are not significantly different in the presence and absence of Na+. The Cl? pump is probably driven by ATP. 相似文献
9.
Yao-ming Huang Sanjiv Maliakal Donald P. Cheney Gregory L. Rorrer 《Journal of phycology》1998,34(5):893-901
Two axenic, in vitro liquid suspension cultures were established for Agardhiella subulata (C. Agardh) Kraft et Wynne, and their growth characteristics were compared. This study illustrated how reliable routes for the development of suspension cultures of macrophytic red algae of terete thallus morphology can be achieved for biotechnology applications. Undifferentiated filament clumps of 2–8 mm diameter were established by induction of callus-like tissue from thallus explants, and lightly branched microplantlets of 2–10 mm length were established by regeneration of filament clumps. The filament clumps were susceptible to regeneration. Adventitious shoot formation was reliably induced from 40% to 70% of the filament clumps by gentle mixing at 100 rev min?1 on an orbital shaker. The specific growth rate of the microplantlets was higher than the filament clumps in nonagitated well plate culture (4%–6% per day for microplantlets vs. 2%–3% per day for filament clumps) at 24° C and 8–36 μmol photons·m?2·s?1 irradiance (10:14 h LD cycle) when grown on ASP12 artificial seawater medium at pH 8.6–8.9 with 20%–25% per day medium replacement. Oxygen evolution rate vs. irradiance measurements showed that relative to the filament clumps, microplantlets had a higher maximum specific oxygen evolution rate (Po,max= 0.181 ± 0.035 vs. 0.130 ± 0.023 mmol O2·g?1 dry cell mass·h?1), but comparable respiration rate (Qo= 0.040 ± 0.013 vs. 0.033 ± 0.017 mmol O2·g?1 dry cell mass·h?1), compensation point (Ic= 3.8 ± 2.4 vs. 5.7 ± 1.2 μmol photons·m?2·s?1), and light intensity at 63.2% of saturation (Ik= 17.5 ± 3.9 vs. 14.9 ± 2.6 μmol photons·m?2·s?1). The microplantlet culture was more suitable for suspension culture development than the filament clump culture because it was morphologically stable and exhibited higher growth rates. 相似文献
10.
A. S. Grutter 《Journal of fish biology》2008,73(9):2094-2109
The rate of emergence of micropredatory gnathiid isopods from the benthos, the proportion of emerging gnathiids potentially eaten by Labroides dimidiatus, and the volume of blood that gnathiids potentially remove from fishes (using gnathiid gut volume) were determined. The abundance (mean ±s.e .) of emerging gnathiids was 41·7 ± 6·9 m?2 day?1 and 4552 ± 2632 reef?1 day?1 (reefs 91–125 m2). The abundance of emerging gnathiids per fish on the reef was 4·9 ± 0·8 day?1; but excluding the rarely infested pomacentrid fishes, it was 20·9 ± 3·8 day?1. The abundance of emerging gnathiids per patch reef was 66 ± 17% of the number of gnathiids that all adult L. dimidiatus per reef eat daily while engaged in cleaning behaviour. If all infesting gnathiids subsequently fed on fish blood, their total gut volume per reef area would be 17·4 ± 5·6 mm3 m?2 day?1; and per fish on the reefs, it would be 2·3 ± 0·5 mm?3 fish?1 day?1 and 10·3 ± 3·1 mm3 fish?1 day?1 (excluding pomacentrids). The total gut volume of gnathiids infesting caged (137 mm standard length, LS) and removed from wild (100–150 mm LS) Hemigymnus melapterus by L. dimidiatus was 26·4 ± 24·6 mm3 day?1 and 53·0 ± 9·6 mm3 day?1, respectively. Using H. melapterus (137 mm LS, 83 g) as a model, gnathiids had the potential to remove, 0·07, 0·32, 0·82 and 1·63% of the total blood volume per day of each fish, excluding pomacentrids, caged H. melapterus and wild H. melapterus, respectively. In contrast, emerging gnathiids had the potential of removing 155% of the total blood volume of Acanthochromis polyacanthus (10·7 mm LS, 0·038 g) juveniles. That L. dimidiatus eat more gnathiids per reef daily than were sampled with emergence traps suggests that cleaner fishes are an important source of mortality for gnathiids. Although the proportion of the total blood volume of fishes potentially removed by blood‐feeding gnathiids on a daily basis appeared to be low for fishes weighing 83 g, the cumulative effects of repeated infections on the health of such fish remains unknown; attacks on small juvenile fishes, may result in possibly lethal levels of blood loss. 相似文献
11.
Δ53β hydroxysteroid dehydrogenase activity transforms biologically inactive Δ53β hydroxy steroids into the active Δ43-keto products (e.g. pregnenolone to progesterone). Using a cytochemical procedure which allows for the continuous microdensitometric monitoring of an enzyme reaction as it proceeds and a well described cytochemical assay for Δ53β HSD we have analysed the initial velocity rates (Vo) for dehydroepiandrosterone (DHEA) binding to this enzyme in regressing (i.e. 20α hydroxy steroid dehydrogenase positive) corpus luteum (CL) cells in unfixed tissue sections (5 μm) of the dioestrous and proestrous rat ovary. The results are mean ± S.E.M. The relationship between DHEA concentration (0 to 50 μM) and Δ53β HSD activity in the dioestrous corpora lutea was sigmoidal and had an atypical 1/Vo versus 1/S plot, the x intercept being positive. Using a 1/Vo versus 1/S2 plot the Vmax was determined to be 1·0 ± 0·08 μmol min?1 mg?1 CL (n = 6). The Hill constant was 2·7 ± 0·02 (n = 6) suggesting a high degree of positive co-operativity for DHEA binding. The S concentration for half maximal activity was 17 ± 1 μmoles (n = 6). In the corpora lutea cells of the proestrous ovary, the Vmax for DHEA transformation was unchanged (0·95 ± 0·04 μmol min?1 mg?1, n = 3) whilst the S0·5 was significantly increased to 27 ± 0·1 (p < 0·01, n = 3). The Hill constant remained positive being 2·9 ± 0·2 (n = 3). NAD+ binding to 3β HSD in regressing corpora lutea of the proestrous ovary has been demonstrated previously to be hyperbolic and fit the classical Michaelis-Menten model.1 Extending the analysis of NAD+ binding to the regressing corpus luteum of the dioestrous rat ovary revealed similar kinetic characteristics to that seen with the proestrous enzyme, the apparent Vmax and Km being 0·84 ± 0·04 μmol min?1 mg?1 CL (n = 3) and 27 ± 7 μmol 1?1 (n = 3) respectively. The Hill constant was 1·1 ± 0·03 (n = 3), indicating no co-operativity of co-factor binding. 相似文献
12.
J.F. Steffensen K. Johansen C.D. Sindberg J.H. Sørensen J.L. Møller 《Journal of experimental marine biology and ecology》1984,84(2):173-178
Ventilation was measured directly in the hagfish, Myxine glutinosa L., by means of an electro-magnetic blood flowmeter. Ventilatory flow and frequency increased from 0.86 ± 0.27 ml·min?, and 18.2 ± 5.1·min?, respectively, at 7°C to 1.70 ± 0.20 ml·min?, and 70.1 ± 9.5·min? at 15 ·C.Standard oxygen consumption,V?O2, was measured in non-buried hagfish. V?O2 was 0.57 ± 0.17μl O2·g?1·min?1 at 7°C, and 0.85 ± 0.12μl O2·g?1·min?1 at 15°C. 相似文献
13.
N. H. Thuy L. A. Tien P. N. Tuyet D. T. T. Huong N. V. Cong M. Bayley T. Wang S. Lefevre 《Journal of fish biology》2010,76(4):1025-1031
Oxygen uptake () and critical oxygen tension (Pcrit) were measured in resting perch Perca fluviatilis that were either fasting or digesting. Digestion caused to double (from 61 to 117 mg O2 kg?1h?1) and was associated with a rise in Pcrit (from 3·4 to 4·9 kPa), showing that the animal's digestive state must be considered when assessing the effect of hypoxia in natural conditions, and when defining optimal oxygen conditions in aquaculture. 相似文献
14.
Erica A. Howard Stith T. Gower Jonathan A. Foley Christopher J. Kucharik 《Global Change Biology》2004,10(8):1267-1284
We calculated carbon budgets for a chronosequence of harvested jack pine (Pinus banksiana Lamb.) stands (0‐, 5‐, 10‐, and~29‐year‐old) and a~79‐year‐old stand that originated after wildfire. We measured total ecosystem C content (TEC), above‐, and belowground net primary productivity (NPP) for each stand. All values are reported in order for the 0‐, 5‐, 10‐, 29‐, and 79‐year‐old stands, respectively, for May 1999 through April 2000. Total annual NPP (NPPT) for the stands (Mg C ha?1 yr?1±1 SD) was 0.9±0.3, 1.3±0.1, 2.7±0.6, 3.5±0.3, and 1.7±0.4. We correlated periodic soil surface CO2 fluxes (RS) with soil temperature to model annual RS for the stands (Mg C ha?1 yr?1±1 SD) as 4.4±0.1, 2.4±0.0, 3.3±0.1, 5.7±0.3, and 3.2±0.2. We estimated net ecosystem productivity (NEP) as NPPT minus RH (where RH was calculated using a Monte Carlo approach as coarse woody debris respiration plus 30–70% of total annual RS). Excluding C losses during wood processing, NEP (Mg C ha?1 yr?1±1 SD) for the stands was estimated to be ?1.9±0.7, ?0.4±0.6, 0.4±0.9, 0.4±1.0, and ?0.2±0.7 (negative values indicate net sources to the atmosphere.) We also calculated NEP values from the changes in TEC among stands. Only the 0‐year‐old stand showed significantly different NEP between the two methods, suggesting a possible mismatch for the chronosequence. The spatial and methodological uncertainties allow us to say little for certain except that the stand becomes a source of C to the atmosphere following logging. 相似文献
15.
K. J. Rodnick A. K. Gamperl K. R. Lizars M. T. Bennett R. N. Rausch E. R. Keeley 《Journal of fish biology》2004,64(2):310-335
Streamside measurements of critical thermal maxima (Tcrit), swimming performance (Ucrit), and routine (Rr) and maximum (Rmax) metabolic rates were performed on three populations of genetically distinct redband trout Oncorhynchus mykiss in the high‐desert region of south‐eastern Oregon. The Tcrit values (29·4 ± 0·1° C) for small (40–140 g) redband trout from the three streams, and large (400–1400 g) redband trout at Bridge Creek were not different, and were comparable to published values for other salmonids. At high water temperatures (24–28° C), large fish incurred higher metabolic costs and were more thermally sensitive than small fish. Ucrit(3·6 ± 0·1 LF s?1), Rr(200 ± 13 mg O2 kg?0·830 h?1) and metabolic power (533 ± 22 mg O2 kg?0·882 h?1) were not significantly different between populations of small redband trout at 24° C. Rmax and metabolic power, however, were higher than previous measurements for rainbow trout at these temperatures. Fish from Bridge Creek had a 30% lower minimum total cost of transport (Cmin), exhibited a lower refusal rate, and had smaller hearts than fish at 12‐mile or Rock Creeks. In contrast, no differences in Ucrit or metabolism were observed between the two size classes of redband trout, although Cmin was significantly lower for large fish at all swimming speeds. Biochemical analyses revealed that fish from 12‐mile Creek, which had the highest refusal rate (36%), were moderately hyperkalemic and had substantially lower circulating levels of free fatty acids, triglycerides and albumin. Aerobic and anaerobic enzyme activities in axial white muscle, however, were not different between populations, and morphological features were similar. Results of this study: 1) suggest that the physiological mechanisms that determine Tcrit in salmonids are highly conserved; 2) show that adult (large) redband trout are more susceptible to the negative affects of elevated temperatures than small redband trout; 3) demonstrate that swimming efficiency can vary considerably between redband trout populations; 4) suggest that metabolic energy stores correlate positively with swimming behaviour of redband trout at high water temperatures; 5) question the use of Tcrit for assessing physiological function and defining thermal habitat requirements of stream‐dwelling salmonids like the redband trout. 相似文献
16.
J. Lucas A. Schouman L. Lyphout X. Cousin C. Lefrancois 《Journal of fish biology》2014,84(4):1171-1178
The relationship between body mass (M) and metabolic rate was investigated through the assessment of active (RA) and standard (RS) metabolic rate at different life stages in zebrafish Danio rerio (5 day‐old larvae, 2 month‐old juveniles and 6 month‐old adults). Scaling exponents and constants were assessed for standard (RS = 0·273M0·965 in mgO2 g?1 h?1) and active metabolic rate (RA = 0·799M0·926 in mgO2 g?1 h?1). These data provide the basis for further experiments regarding the effects of environmental factors on aerobic metabolism throughout the life cycle of this species. 相似文献
17.
P. O. Vardevanyan A. P. Antonyan G. A. Manukyan A. T. Karapetyan A. K. Shchyolkina O. F. Borisova 《Molecular Biology》2000,34(2):272-276
Isotherms of the EtBr adsorption on native and denatured poly(dA)poly(dT) in the temperature interval 20–70°C were obtained.
The EtBr binding constants and the number of binding sites were determined. The thermodynamic parameters of the EtBr intercalation
complex upon changes of solution temperature 20–48°C were calculated: 1.0·106 M−1≤K≤1.4·106 M−1, free energy ΔG
o=−8.7±0.3 kcal/mol, enthalpy ΔH
o≅0, and entropy ΔS
o=28±0.5 cal/(mol deg). UV melting has shown that the melting temperature (T
m) of EtBr-poly(dA)poly(dT) complexes (μ=0.022,4.16·10−5 M EtBr) increased by 17°C as compared with the ΔT
m of free homopolymer, whereas the half-width of the transition (T
m) is not changed. It was shown for the first time that EtBr forms complexes of two types on single-stranded regions of poly(dA)poly(dT)
denatured at 70°C: strong (K
1=1.7·105 M−1; ΔG
o=−8.10±0.03 kcal/mol) and weak (K
2=2.9·103 M−1; ΔG
o=−6.0±0.3 kcal/mol).The ΔG
o of the strong and weak complexes was independent of the solution ionic strength, 0.0022≤μ≤0.022. A model of EtBr binding
with single-stranded regions of poly(dA)poly(dT) is discussed. 相似文献
18.
The growth of Nile tilapia Oreochromis niloticus (0·02–20·00 g) was measured when fed to excess during the hours of light, following their exposure to five thermal regimes fluctuating around the thermal optimum for growth (Topt = 30° C) over the diel cycle of day (light, L) and night (dark, N), i.e. 27° C(L):33° C(N), 28·5° C(L):31·5° C(N), 30° C(L):30° C(N), 31·5° C(L):28·5° C(N) and 33° C(L):27° C(N) (two replicates per treatment, six weeks' rearing, growth measurements at weekly intervals). A model constructed with a stepwise multiple‐regression analysis accounted for 87·4% of the variation of the specific growth rate (G, % M day?1) from the variations of wet mass (M), the extent of the thermal fluctuation (FT) and their interactions, i.e. log10G = 1·7686 ? 0·2136 log10M + 0·0806 [log 10M× log 10 (1 + FT)] ? 0·0394 [log10M× log 10 (1 + FT)]2. Based on this model, the thermal fluctuation that produces the fastest growth ( ,°C) decreases in a curvilinear way, from 5·1° C at 20 mg to c. 0·7° C at 20 g. Thermal regimes that produce the slowest growth also produce the highest size heterogeneity. Functional hypotheses behind the size‐dependent effects of thermal fluctuations are discussed, together with their implications in natural habitats and aquaculture systems with in different contexts of food availability. 相似文献
19.
Hiroshi Takashima Ayako Araki Keiko Takemoto Naokazu Yoshikawa Keiichi Tsukahara 《Journal of biological inorganic chemistry》2006,11(3):316-324
In order to understand the detailed mechanism of the stereoselective photoinduced electron-transfer (ET) reactions of zinc-substituted
myoglobin (ZnMb) with optically active molecules by flash photolysis, we designed and prepared new optically active agents,
such as N,N′-dimethylcinchoninium diiodide ([MCN]I2) and N,N′-dimethylcinchonidinium diiodide ([MCD]I2). The photoexcited triplet state of ZnMb, 3(ZnMb)*, was successfully quenched by [MCN]2+ and [MCD]2+ ions to form the radical pair of ZnMb cation (ZnMb·+) and reduced [MCN]·+ and [MCD]·+, followed by a thermal back ET reaction to the ground state. The rate constants (k
q) for the ET quenching at 25 °C were obtained as k
q(MCN)=(1.9±0.1)×106 M−1 s−1 and k
q(MCD)=(3.0±0.2)×106 M−1 s−1, respectively. The ratio of k
q(MCD)/k
q(MCN)=1.6 indicates that the [MCD]2+ preferentially quenches 3(ZnMb)*. The second-order rate constants (k
b) for the thermal back ET reaction from [MCN]·+ and [MCD]·+ to ZnMb·+ at 25 °C were k
b(MCN)=(0.79±0.04)×108 M−1 s−1 and k
b(MCD)=(1.0±0.1)×108 M−1 s−1, respectively, and the selectivity was k
q(MCD)/k
q(MCN)=1.3. Both quenching and thermal back ET reactions are controlled by the ET step. In the quenching reaction, the energy
differences of ΔΔH
≠(MCD–MCN) and ΔΔS
≠(MCD–MCN) at 25 °C were obtained as −1.1 and 0 kJ mol−1, respectively. On the other hand, ΔΔH
≠(MCD–MCN)=11±2 kJ mol−1 and TΔΔS
≠(MCD–MCN)=−10±2 kJ mol−1 were given in the thermal back ET reaction. The highest stereoselectivity of 1.7 for [MCD]·+ found at low temperature (10 °C) was due to the ΔΔS
≠ value obtained in the thermal back ET reaction.
Electronic Supplementary Material Supplementary material is available for this article at and is accessible for authorized users. 相似文献
20.
M. J. Young 《Journal of fish biology》2009,75(7):1888-1894
For stage four anaesthesia of the western rainbowfish Melanotaenia australis the most efficacious concentration of AQUI‐S® was found to be 80 mg l?1 when five different doses were tested at 27° C (range 26·5–27·5° C). This gave a mean ±s.e. (n = 10) induction time of 140·4 ± 8·9 s and recovery time of 180·2 ± 8·9 s and resulted in 10% mortality when fish were continuously exposed for 15 min. All fish given this dose during induction and recovery time trials ate within 1 h of recovery, and there was zero mortality during a subsequent 1 month monitoring period. 相似文献