A test of the rapid measurement of leaf photosynthesis-intercellular CO2 concentration response curve of an evergreen shrub Viburnum Odoratissimum

2021 ◽  
Author(s):  
Quanhong Lin ◽  
Changti Zhao ◽  
Zhenyue Liu ◽  
Di Tian
Keyword(s):  
Maximum Rate ◽  
Response Curve ◽  
Intercellular Co2 Concentration ◽  
Limiting Factors ◽  
Response Curves ◽  
Evergreen Species ◽  
Viburnum Odoratissimum ◽  
Gas Exchange System ◽  
Measurement Efficiency ◽  
Detecting Method

<p>Plant photosynthetic physiology is a crucial process reflecting plant growth and productivity. The maximum rate of Rubisco carboxylation (<em>V<sub>c,max</sub></em>) and the maximum rate of electron transport (<em>J<sub>max</sub></em>) of plant leaves are the main limiting factors of photosynthetic capacity and indispensable parameters in ecosystem mechanism models. Accurate simulation of <em>V<sub>c,max</sub></em> and <em>J<sub>max</sub></em> is vital to improve the prediction precision of vegetation dynamics under the background of climate changes. However, using traditional CO<sub>2</sub> response curves to obtain <em>V<sub>c,max</sub></em> and <em>J<sub>max</sub></em> was time-consuming (about 30 to 60 minutes for each CO<sub>2</sub> response curve) and labor-intensive in the field. The rapid photosynthesis-intercellular CO<sub>2</sub> concentration (A-Ci) response technique (RACiR) provided a potential convenient way to obtain A-Ci curve in an open gas exchange system, which would greatly improve the measurement efficiency. Nevertheless, whether the RACiR detecting method verified by limited conifers and deciduous species (especially poplar trees) in previous studies could be generally used for other plant functional groups remains unclear.</p><p> </p><p>Therefore, here we selected <em>Viburnum Odoratissimum</em> as the target and used Li-cor 6800 to test the applicability of the rapid RACiR detecting method on evergreen species. As the changes of CO<sub>2</sub> ranges and rates are the most important parameters in the method, we set 10 different change ranges of reference [CO<sub>2</sub>] (i.e., 400-1500 ppm, 400-200-800 ppm, 420-20-620 ppm, 420-20-820 ppm, 420-20-1020 ppm, 420-20-1220 ppm, 420-20-1520 ppm, 420-20-1820 ppm, 450-50-650 ppm, 650-50-650 ppm) to verify the accuracy of traditional CO<sub>2</sub> response curves and RACiR and to explore suitable [CO<sub>2</sub>] change ranges for evergreen species.</p><p> </p><p>Finally, our results showed that <em>V<sub>c,max</sub></em> and <em>J<sub>max</sub></em> calculated by 10 rapid A-Ci response curves except <em>J<sub>max</sub></em> calculated by 650-50-650 ppm [CO<sub>2</sub>] were not significantly different from those calculated by traditional A-Ci response curves. Moreover, 400-200-800 ppm [CO<sub>2</sub>] compared with the other [CO<sub>2</sub>] ranges was suitable for <em>V. Odoratissimum</em>. Our results indicated the advantage of RACiR method for evergreen species and implied that preliminary experiments should be carried out according to specific tree species to determine the most appropriate change range of [CO<sub>2</sub>] when using RACiR to calculate <em>V<sub>c,max</sub></em> and <em>J<sub>max</sub></em>.</p>

Factor VII Clotting Assay: Influence of Different Thromboplastins and Factor VII-Deficient Plasmas

1991 ◽  
Vol 65 (02) ◽  
pp. 160-164 ◽  
Author(s):  
Marina Poggio ◽  
Armando Tripodi ◽  
Guglielmo Mariani ◽  
Pier Mannuccio Mannucci ◽  
Keyword(s):  
Heart Disease ◽  
Ischemic Heart Disease ◽  
Dose Response ◽  
Response Curve ◽  
Ischemic Heart ◽  
Factor Vii ◽  
Response Curves ◽  
Assay Sensitivity ◽  
Clinical Laboratories ◽  
Coagulant Activity

SummaryBeing a putative predictor of ischemic heart disease, the measurement of factor VII (FVTI) coagulant activity will be presumably requested to clinical laboratories with increasing frequency. To assess the influence on FVII assays of different thromboplastins and FVII-deficient plasmas we compared performances of all possible combinations of 5 thromboplastins and 6 deficient plasmas. The reproducibility of the clotting times of the dose-response curves for human and rabbit thromboplastins were acceptable (CV lower than 7%), whereas bovine thromboplastin had a higher CV. Reproducibility was very similar for all deficient plasmas when they were used in combination with a given thromboplastin. Responsiveness of the dose-response curve did not depend on the deficient plasma but rather on the thromboplastin: one rabbit thromboplastin was the least responsive, the bovine thromboplastin the most responsive, the human and the remaining two rabbit thromboplastins had intermediate responsiveness. Assay sensitivity to cold-activated FVII varied according to the thromboplastin: the bovine thromboplastin was the most sensitive, the human thromboplastin the least sensitive, of the three rabbit thromboplastins two were relatively sensitive, one was almost insensitive. In conclusion, our results indicate that thromboplastin rather than deficient plasma is the crucial factor in the standardization of FVII assay.

OVARIAN ASCORBIC ACID DEPLETION TEST FOR LUTEINIZING HORMONE

1967 ◽  
Vol 56 (4) ◽  
pp. 619-625 ◽  
Author(s):  
Hans Jacob Koed ◽  
Christian Hamburger
Keyword(s):  
Ascorbic Acid ◽  
Luteinizing Hormone ◽  
Dose Response ◽  
Response Curve ◽  
Dose Response Curve ◽  
Human Origin ◽  
Response Curves ◽  
Significant Difference ◽  
The Mean ◽  
Different Levels

ABSTRACT Comparison of the dose-response curves for LH of ovine origin (NIH-LH-S8) and of human origin (IRP-HMG-2) using the OAAD test showed a small, though statistically significant difference, the dose-response curve for LH of human origin being a little flatter. Two standard curves for ovine LH obtained with 14 months' interval, were parallel but at different levels of ovarian ascorbic acid. When the mean ascorbic acid depletions were calculated as percentages of the control levels, the two curves for NIH-LH-S8 were identical. The use of standards of human origin in the OAAD test for LH activity of human preparations is recommended.

Method for testing antiserum titer and avidity in nephelometric systems.

1981 ◽  
Vol 27 (11) ◽  
pp. 1838-1844 ◽  
Author(s):  
G A Hudson ◽  
R F Ritchie ◽  
J E Haddow
Keyword(s):  
Dose Response ◽  
Response Curve ◽  
Direct Evidence ◽  
Reaction Rates ◽  
Dose Response Curve ◽  
Antigen Concentration ◽  
Response Curves ◽  
Binding Strength ◽  
Antiserum Dilution ◽  
Antiserum Titer

Abstract Antiserum performance in a nephelometric system can be characterized by parameters derived from measuring reaction rates. The characterization process is derived from a series of dose-response curves (elicited nephelometric response vs antigen concentration) generated from various dilutions of the antiserum being tested. Antiserum titer can then be calculated by plotting the antigen concentration found at one-half the maximum nephelometric response (Hmax) of each dose-response curve (C50) vs the corresponding antiserum dilution. Antiserum avidity can be calculated by plotting Hmax against its corresponding antiserum concentration. After general expressions are determined for C50 and Hmax vs antiserum concentration, a single dose-response curve suffices for characterizing antisera with respect to titer and avidity. Direct evidence is provided for the validity of C50 and Hmax as measures of titer and avidity by correlating these parameters with antiserum binding strength and with the number of antibodies eluted from immobilized antigen. This method can be applied to evaluate and compare different antiserum lots having the same specificity, to identify reagent inadequacies by comparing antisera of different specificity, and to predict the optimal antiserum dilution to use in performing an assay.

Oxytocin as an antidiuretic hormone. II. Role of V2 vasopressin receptor

1995 ◽  
Vol 269 (1) ◽  
pp. F78-F85 ◽  
Author(s):  
C. L. Chou ◽  
S. R. DiGiovanni ◽  
A. Luther ◽  
S. J. Lolait ◽  
M. A. Knepper
Keyword(s):  
Dose Response ◽  
Water Permeability ◽  
Response Curve ◽  
Collecting Duct ◽  
Oxytocin Receptor ◽  
Dose Response Curve ◽  
Vasopressin Receptor ◽  
Response Curves ◽  
V2 Receptor ◽  
V2 Vasopressin Receptor

We conducted this study to determine what receptor mediates the effect of oxytocin to increase osmotic water permeability (Pf) in the rat inner medullary collecting duct (IMCD). Reverse transcription-polymerase chain reaction (RT-PCR) experiments demonstrated that mRNA for both the oxytocin receptor and the V2 receptor is present in the rat terminal IMCD. In isolated perfused IMCD segments, we found that the V2 vasopressin receptor antagonist [d(CH2)5(1),D-Ile2,Ile4,Arg8]vasopressin, but not oxytocin receptor antagonists, blocked the hydrosmotic response to 200 pM oxytocin. The selective oxytocin receptor agonist [Thr4,Gly7]oxytocin did not increase water permeability. Oxytocin also increased urea permeability in IMCD segments. Studies in IMCD suspensions showed that oxytocin increases adenosine 3',5'-cyclic monophosphate production in a dose-dependent fashion with a half-maximal (EC50) response at 5.2 nM. The dose-response curves were virtually identical for IMCD suspensions from Sprague-Dawley rats and Brattleboro rats. The oxytocin dose-response curve was displaced to the right of the vasopressin dose-response curve (EC50, 0.44 nM). From these results, we conclude that the V2 receptor mediates the hydrosmotic action of oxytocin in rat IMCD.

A Study of the Acid Dose-Response Curve to Small Doses of Pentagastrin in Duodenal Ulcer Patients

1972 ◽  
Vol 43 (2) ◽  
pp. 181-191
Author(s):  
J. B. Elder ◽  
G. Gillespie ◽  
E. H. G. Campbell ◽  
I. E. Gillespie ◽  
G. P. Crean ◽  
...  
Keyword(s):  
Duodenal Ulcer ◽  
Body Weight ◽  
Dose Response ◽  
Response Curve ◽  
Acid Output ◽  
Twilight Zone ◽  
Response Curves ◽  
Small Doses ◽  
Threshold Doses ◽  
Body Weight Dose

1. The acid secretory responses to a range of small doses of pentagastrin in 0·15 m-NaCl have been studied in thirty-one preoperative duodenal ulcer subjects. Acid output increased significantly above basal values when a dose of 0·064 μg h−1 kg−1 was given. 2. Control observations in sixteen duodenal ulcer patients using the saline solvent alone at identical rates of infusion showed no significant increase in acid output. 3. From the dose-response curves sub-threshold and threshold doses of pentapeptide are suggested for duodenal ulcer patients before truncal vagotomy. 4. Considerable variation in acid response was noted between patients given the same body-weight dose of pentapeptide. The results suggest that a ‘twilight zone’ of stimulation exists between the dose of pentagastrin by which few patients are stimulated and the dose by which the majority are stimulated. This may reflect some variation in the sensitivity to stimulation by pentagastrin from one patient to another.

scholarly journals Challenges in modelling isoprene and monoterpene emission dynamics of Arctic plants: a case study from a subarctic tundra heath

2016 ◽  
Vol 13 (24) ◽  
pp. 6651-6667 ◽  
Author(s):  
Jing Tang ◽  
Guy Schurgers ◽  
Hanna Valolahti ◽  
Patrick Faubert ◽  
Päivi Tiiva ◽  
...  
Keyword(s):  
Response Curve ◽  
Large Scale ◽  
Ecosystem Model ◽  
The Arctic ◽  
Short Term ◽  
Response Curves ◽  
Arctic Plants ◽  
Scale Modelling

Abstract. The Arctic is warming at twice the global average speed, and the warming-induced increases in biogenic volatile organic compounds (BVOCs) emissions from Arctic plants are expected to be drastic. The current global models' estimations of minimal BVOC emissions from the Arctic are based on very few observations and have been challenged increasingly by field data. This study applied a dynamic ecosystem model, LPJ-GUESS, as a platform to investigate short-term and long-term BVOC emission responses to Arctic climate warming. Field observations in a subarctic tundra heath with long-term (13-year) warming treatments were extensively used for parameterizing and evaluating BVOC-related processes (photosynthesis, emission responses to temperature and vegetation composition). We propose an adjusted temperature (T) response curve for Arctic plants with much stronger T sensitivity than the commonly used algorithms for large-scale modelling. The simulated emission responses to 2 °C warming between the adjusted and original T response curves were evaluated against the observed warming responses (WRs) at short-term scales. Moreover, the model responses to warming by 4 and 8 °C were also investigated as a sensitivity test. The model showed reasonable agreement to the observed vegetation CO2 fluxes in the main growing season as well as day-to-day variability of isoprene and monoterpene emissions. The observed relatively high WRs were better captured by the adjusted T response curve than by the common one. During 1999–2012, the modelled annual mean isoprene and monoterpene emissions were 20 and 8 mg C m−2 yr−1, with an increase by 55 and 57 % for 2 °C summertime warming, respectively. Warming by 4 and 8 °C for the same period further elevated isoprene emission for all years, but the impacts on monoterpene emissions levelled off during the last few years. At hour-day scale, the WRs seem to be strongly impacted by canopy air T, while at the day–year scale, the WRs are a combined effect of plant functional type (PFT) dynamics and instantaneous BVOC responses to warming. The identified challenges in estimating Arctic BVOC emissions are (1) correct leaf T estimation, (2) PFT parameterization accounting for plant emission features as well as physiological responses to warming, and (3) representation of long-term vegetation changes in the past and the future.

New Algorithm of Response Curve for Fitting HDR Image

2019 ◽  
Vol 34 (01) ◽  
pp. 2054001 ◽  
Author(s):  
Shi Qiu ◽  
Xuemei Li ◽  
Yongdong Huang ◽  
Zhengzhou Li ◽  
Xun Chen ◽  
...  
Keyword(s):  
Response Curve ◽  
Image Sequences ◽  
Response Curves ◽  
Time Intervals ◽  
Optimal Response ◽  
Fitting Method ◽  
Fitting Algorithm ◽  
Texture Characteristics ◽  
Pixel Value ◽  
Hdr Image

Based on the process of generating HDR images from LDR image sequences with different light exposures in the same scene, a new fitting method of camera response curves is proposed to solve the problem that the boundary of the fitting algorithm of camera response curves will be blurred and it is difficult to determine and verify the accuracy of the fitting curves. The optimal response curve is fitted by increasing LDR images step by step through considering the pixel value and texture characteristics. In order to validate the fitting effect of curves, we compare the photographed images and the real images in different time intervals on the basis of HDR images and response curves. We use RGB and gray image experiments to compare the current mainstream algorithms and the accuracy of our proposed algorithm can reach 96%, which has robustness.

Corrigendum - Effects of a water stress on the photosynthesis and respiration of wheat ears

1980 ◽  
Vol 31 (5) ◽  
pp. 857
Author(s):  
B Marshall ◽  
RH Sedgley ◽  
PV Biscoe
Keyword(s):  
Carbon Dioxide ◽  
Water Stress ◽  
Maximum Rate ◽  
Dark Respiration ◽  
Light Response ◽  
Grain Filling ◽  
Response Curves ◽  
Rectangular Hyperbola ◽  
Wheat Leaves ◽  
Days After Anthesis

An experiment was conducted on Huntsman winter wheat to investigate the effects of a water stress applied at anthesis on the carbon dioxide exchange of the ears during grain filling. The water stress was created by excluding rain from the soil, not the foliage, of plants growing in the field. Control plants were well watered throughout the period when the treatment was imposed. At intervals for 32 days after anthesis, detailed measurements were made of the photosynthetic rate of ears at different irradiances and rates of ear dark respiration. The measurements were analysed by using the photosynthesis-light response model developed by Marshall and Biscoe (1980) for wheat leaves with a modification for the pathway of respiration from the grains to the glumes. The model is a non-rectangular hyperbola and uses four parameters: Pn,max (maximum rate of net photosynthesis), Rd (rate of dark respiration), � (photochemical efficiency at low light), and F (ratio of physical to total resistance to diffusion of carbon dioxide). Analysis showed that in wheat ears during grain filling, photosynthesis can be treated as occurring predominantly in the glumes and respiration in the grains. The shape of the photosynthesis-light response curves for ears from both treatments were similar, but differed from those for wheat leaves because the maximum rates of photosynthesis were reached more gradually with increasing irradiance. However, the measured response curves were still better fitted by the model than a rectangular hyperbola which has often been used in the past. The water stress at anthesis decreased the maximum rate of ear photosynthesis by 0.8 g carbon dioxide m-2 h-1 throughout the grain-filling period. Initially, the rates of ear respiration were the same, but 32 days after anthesis the treatment had decreased ear respiration rate from 0.04 to 0.01 g carbon dioxide h-1/grain.

Regulation of Carboxylation and Photosynthetic Oscillations During Sun-Shade Acclimation in Helianthus annuus Measured With a Rapid-Response Gas Exchange System

1988 ◽  
Vol 15 (2) ◽  
pp. 239 ◽  
Author(s):  
CB Osmond ◽  
V Oja ◽  
A Laisk
Keyword(s):  
Gas Exchange ◽  
Intercellular Co2 Concentration ◽  
Photosynthetic Apparatus ◽  
Co2 Concentration ◽  
Rapid Response ◽  
Exchange System ◽  
Dynamic Regulation ◽  
Bisphosphate Carboxylase ◽  
Shade Acclimation ◽  
Gas Exchange System

The consequences of acclimation from shade to sun and vice versa for regulated photosynthetic metabolism were examined in H. annuus. A rapid-response gas exchange system was used to assess changes in carboxylation-related parameters (mesophyll conductance, assimilatory charge and CO2 capacity) and to analyse oscillations in CO2 fixation following transfer to high CO2 concentration as a function of intercellular CO2 concentration and light intensity. Data showed a two- to threefold change in all carboxylation-related parameters during acclimation in either direction. Dynamic regulation of carboxylation, indicated by changes in oscillatory response as a function of CO2 concentration at light saturation, remained unchanged, consistent with concerted regulation of ribulose-1,5-bisphosphate carboxylase-oxygenase during acclimation. However, the light dependency of oscillations changed during acclimation from shade to sun, and the range of oscillation was closely tied to the maximum rate of steady-state photosynthesis at CO2 saturation. These data imply that changes in the light-absorbing and electron transport components of the photosynthetic apparatus underlie the shift in regulatory behaviour during acclimation.

Implications of hormesis on the bioassay and hazard assessment of chemical carcinogens

1998 ◽  
Vol 17 (5) ◽  
pp. 254-258 ◽  
Author(s):  
Justin G Teeguarden ◽  
Yvonne P Dragan ◽  
Henry C Pitot
Keyword(s):  
Hazard Assessment ◽  
Dose Response ◽  
Response Curve ◽  
Dose Response Curve ◽  
Low Doses ◽  
Response Curves ◽  
Large Numbers ◽  
Carcinogenic Agents ◽  
Assessment Guidelines ◽  
Study Designs

Hormesis has been defined as a dose-response relationship which depicts improvement in some endpoint (increased metabolic rates, reduction in tumor incidence, etc.) at low doses of a toxic compound followed by a decline in the endpoint at higher doses. The existence of hormetic responses to carcinogenic agents has several implications for the bioassay and hazard assessment of carcinogens. To be capable of detecting and statistically testing for hormetic or other nonlinear dose-response functions, current study designs must be modified to include lower doses and sufficiently large numbers of animals. In addition, improved statistical methods for testing nonlinear dose-response relationships will have to be developed. Research integrating physiologically-based pharmacokinetic model descriptions of target dose with mechanistic data holds the greatest promise for improving the description of the dose-response curve at low doses. The 1996 Proposed Carcinogen Risk Assessment Guidelines encourage the use of mechanistic data to improve the descriptions of the dose-response curve at low doses, but do not distinguish between the types of nonlinear dose-response curves. Should this refined approach lead to substantial support for hormesis in carcinogenic processes, future guidelines will need to provide guidance on establishing safe doses and communicating the results to the public.

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