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1.
2.
Xifeng Wang Gang Cheng Yan Lu Chenglin Zhang Xiaobing Wu Haitang Han Yaofeng Zhao Liming Ren 《PloS one》2016,11(2)
Crocodilians are evolutionarily distinct reptiles that are distantly related to lizards and are thought to be the closest relatives of birds. Compared with birds and mammals, few studies have investigated the Ig light chain of crocodilians. Here, employing an Alligator sinensis genomic bacterial artificial chromosome (BAC) library and available genome data, we characterized the genomic organization of the Alligator sinensis IgL gene loci. The Alligator sinensis has two IgL isotypes, λ and κ, the same as Anolis carolinensis. The Igλ locus contains 6 Cλ genes, each preceded by a Jλ gene, and 86 potentially functional Vλ genes upstream of (Jλ-Cλ)n. The Igκ locus contains a single Cκ gene, 6 Jκs and 62 functional Vκs. All VL genes are classified into a total of 31 families: 19 Vλ families and 12 Vκ families. Based on an analysis of the chromosomal location of the light chain genes among mammals, birds, lizards and frogs, the data further confirm that there are two IgL isotypes in the Alligator sinensis: Igλ and Igκ. By analyzing the cloned Igλ/κ cDNA, we identified a biased usage pattern of V families in the expressed Vλ and Vκ. An analysis of the junctions of the recombined VJ revealed the presence of N and P nucleotides in both expressed λ and κ sequences. Phylogenetic analysis of the V genes revealed V families shared by mammals, birds, reptiles and Xenopus, suggesting that these conserved V families are orthologous and have been retained during the evolution of IgL. Our data suggest that the Alligator sinensis IgL gene repertoire is highly diverse and complex and provide insight into immunoglobulin gene evolution in vertebrates. 相似文献
3.
Artur Stefanski Raimundo Bermudez Kerrie M. Sendall Rebecca A. Montgomery Peter B. Reich 《Global Change Biology》2020,26(2):746-759
Photosynthetic biochemical limitation parameters (i.e., Vcmax, Jmax and Jmax:Vcmax ratio) are sensitive to temperature and water availability, but whether these parameters in cold climate species at biome ecotones are positively or negatively influenced by projected changes in global temperature and water availability remains uncertain. Prior exploration of this question has largely involved greenhouse based short‐term manipulative studies with mixed results in terms of direction and magnitude of responses. To address this question in a more realistic context, we examined the effects of increased temperature and rainfall reduction on the biochemical limitations of photosynthesis using a long‐term chamber‐less manipulative experiment located in northern Minnesota, USA. Nine tree species from the boreal‐temperate ecotone were grown in natural neighborhoods under ambient and elevated (+3.4°C) growing season temperatures and ambient or reduced (≈40% of rainfall removed) summer rainfall. Apparent rubisco carboxylation and RuBP regeneration standardized to 25°C (Vcmax25°C and Jmax25°C, respectively) were estimated based on ACi curves measured in situ over three growing seasons. Our primary objective was to test whether species would downregulate Vcmax25°C and Jmax25°C in response to warming and reduced rainfall, with such responses expected to be greatest in species with the coldest and most humid native ranges, respectively. These hypotheses were not supported, as there were no overall main treatment effects on Vcmax25°C or Jmax25°C (p > .14). However, Jmax:Vcmax ratio decreased significantly with warming (p = .0178), whereas interactions between warming and rainfall reduction on the Jmax25°C to Vcmax25°C ratio were not significant. The insensitivity of photosynthetic parameters to warming contrasts with many prior studies done under larger temperature differentials and often fixed daytime temperatures. In sum, plants growing in relatively realistic conditions under naturally varying temperatures and soil moisture levels were remarkably insensitive in terms of their Jmax25°C and Vcmax25°C when grown at elevated temperatures, reduced rainfall, or both combined. 相似文献
4.
Patients with Sjögren's syndrome (SS) have characteristic lymphocytic infiltrates of the salivary glands. To determine whether the B cells accumulating in the salivary glands of SS patients represent a distinct population and to delineate their potential immunopathologic impact, individual B cells obtained from the parotid gland and from the peripheral blood were analyzed for immunglobulin light chain gene rearrangements by PCR amplification of genomic DNA. The productive immunglobulin light chain repertoire in the parotid gland of the SS patient was found to be restricted, showing a preferential usage of particular variable lambda chain genes (Vλ2E) and variable kappa chain genes (VκA27). Moreover, clonally related VL chain rearrangements were identified; namely, VκA27–Jκ5 and VκA19–Jκ2 in the parotid gland, and Vλ1C–Jλ3 in the parotid gland and the peripheral blood. Vκ and Vλ rearrangements from the parotid gland exhibited a significantly elevated mutational frequency compared with those from the peripheral blood (P < 0.001). Mutational analysis revealed a pattern of somatic hypermutation similar to that found in normal donors, and a comparable impact of selection of mutated rearrangements in both the peripheral blood and the parotid gland. These data indicate that there is biased usage of VL chain genes caused by selection and clonal expansion of B cells expressing particular VL genes. In addition, the data document an accumulation of B cells bearing mutated VL gene rearrangements within the parotid gland of the SS patient. These results suggest a role of antigen-activated and selected B cells in the local autoimmune process in SS. 相似文献
5.
6.
The parameters estimated from traditional A/C
i curve analysis are dependent upon some underlying assumptions that substomatal CO2 concentration (C
i) equals the chloroplast CO2 concentration (C
c) and the C
i value at which the A/C
i curve switches between Rubisco- and electron transport-limited portions of the curve (C
i-t) is set to a constant. However, the assumptions reduced the accuracy of parameter estimation significantly without taking
the influence of C
i-t value and mesophyll conductance (g
m) on parameters into account. Based on the analysis of Larix gmelinii’s A/C
i curves, it showed the C
i-t value varied significantly, ranging from 24 Pa to 72 Pa and averaging 38 Pa. t-test demonstrated there were significant differences in parameters respectively estimated from A/C
i and A/C
c curve analysis (p<0.01). Compared with the maximum ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) carboxylation rate (Vcmax), the maximum electron transport rate (Jmax) and Jmax/Vcmax estimated from A/C
c curve analysis which considers the effects of g
m limit and simultaneously fits parameters with the whole A/C
c curve, mean Vcmax estimated from A/C
i curve analysis (Vcmax-C
i) was underestimated by 37.49%; mean Jmax estimated from A/C
i curve analysis (Jmax-C
i) was overestimated by 17.8% and (Jmax-C
i)/(Vcmax-C
i) was overestimated by 24.2%. However, there was a significant linear relationship between Vcmax estimated from A/C
i curve analysis and Vcmax estimated from A/C
c curve analysis, so was it Jmax (p<0.05). 相似文献
7.
Yoshiaki Iwasaki Hiroyuki Takabatake Marc Monestier Soldano Ferrone 《Immunogenetics》1995,42(2):90-100
The anti-HLA-DQ3 monoclonal antibodies (mAb) KS13, SO1, SO2, SO3, SO4, and SO5 recognize spatially close but distinct antigenic determinants, since they crossinhibit each other in their binding to HLA-DQ3 antigens, but do not share idiotopes recognized in their antigen combining site by syngeneic and anti-id antisera and mAb. Furthermore, mAb SO1, SO3, SO4, and SO5 react also with HLA-DQ allospecificities other than HLA-DQ3. Sequence analysis of the heavy (V
H
) and light (V
L
) chain variable region of the six mAb revealed preferential usage of V
H
36–60 and V
K
12/13 gene families. However, the individual V
H
and V
L
germline gene usage by the six mAb is diverse and the utilization of D, J
H
, and J
L
gene segments is heterogeneous. The diverse usage of V
H
and V
L
gene segments and heterogeneous amino acid sequences of V
H
and V
L
CDR, together with the heterogeneous idiotypic profile, may reflect the complexity of the determinants recognized by the six mAb on HLA-DQ3 antigens. The results we have presented provide for the first time information about the structural basis of the diversity of antibodies recognizing human histocompatibility antigens.The nucleotide sequence data reported in this Papershave been submitted to the GenBank nucleotide sequence database and have been assigned the accession numbers L20499, L20957, L20961, L24557, L24558 and L20962, respectively, for V
H
region genes, and L20956, L20958, L24555, L24556, L20959, and L20960, respectively, for V
L
region genes 相似文献
8.
Norman Wang William F. Smith Brian R. Miller Dikran Aivazian Alexey A. Lugovskoy Mitchell E. Reff Scott M. Glaser Lisa J. Croner Stephen J. Demarest 《Proteins》2009,76(1):99-114
Engineered antibodies are a large and growing class of protein therapeutics comprising both marketed products and many molecules in clinical trials in various disease indications. We investigated naturally conserved networks of amino acids that support antibody VH and VL function, with the goal of generating information to assist in the engineering of robust antibody or antibody‐like therapeutics. We generated a large and diverse sequence alignment of V‐class Ig‐folds, of which VH and VL domains are family members. To identify conserved amino acid networks, covariations between residues at all possible position pairs were quantified as correlation coefficients (?‐values). We provide rosters of the key conserved amino acid pairs in antibody VH and VL domains, for reference and use by the antibody research community. The majority of the most strongly conserved amino acid pairs in VH and VL are at or adjacent to the VH–VL interface suggesting that the ability to heterodimerize is a constraining feature of antibody evolution. For the VH domain, but not the VL domain, residue pairs at the variable‐constant domain interface (VH–CH1 interface) are also strongly conserved. The same network of conserved VH positions involved in interactions with both the VL and CH1 domains is found in camelid VHH domains, which have evolved to lack interactions with VL and CH1 domains in their mature structures; however, the amino acids at these positions are different, reflecting their different function. Overall, the data describe naturally occurring amino acid networks in antibody Fv regions that can be referenced when designing antibodies or antibody‐like fragments with the goal of improving their biophysical properties. Proteins 2009. © 2008 Wiley‐Liss, Inc. 相似文献
9.
O. Urban A. Ač J. Kalina T. Priwitzer M. Šprtová V. Špunda M. V. Marek 《Photosynthetica》2007,45(3):392-399
Temperature responses of carbon assimilation processes were studied in four dominant species from mountain grassland ecosystem,
i.e. Holcus mollis (L.), Hypericum maculatum (Cr.), Festuca rubra (L.), and Nardus stricta (L.), using the gas exchange technique. Leaf temperature (T
L) of all species was adjusted within the range 13–30 °C using the Peltier thermoelectric cooler. The temperature responses
of metabolic processes were subsequently modelled using the Arrhenius exponential function involving the temperature coefficient
Q
10. The expected increase of global temperature led to a significant increase of dark respiration rate (R
D; Q
10 = 2.0±0.5), maximum carboxylation rate (V
Cmax; Q
10 = 2.2±0.6), and maximum electron transport rate (J
max; Q
10 = 1.6±0.4) in dominant species of mountain grassland ecosystems. Contrariwise, the ratio between J
max and V
Cmax linearly decreased with T
L [y = −0.884 T
L + 5.24; r
2 = 0.78]. Hence temperature did not control the ratio between intercellular and ambient CO2 concentration, apparent quantum efficiency, and photon-saturated CO2 assimilation rate (P
max). P
max primarily correlated with maximum stomatal conductance irrespective of T
L. Water use efficiency tended to decrease with T
L [y = −0.21 T
L + 8.1; r
2 = 0.87]. 相似文献
10.
11.
James C. Kathilankal Thomas J. Mozdzer José D. Fuentes Karen J. McGlathery Paolo D’Odorico Jay C. Zieman 《Hydrobiologia》2011,669(1):167-181
Physiological measurements were used to investigate the dependence of photosynthesis on light, temperature, and intercellular
carbon dioxide (CO2) levels in the C4 marsh grass Spartina alterniflora. Functional relationships between these environmental variables and S. alterniflora physiological responses were then used to improve C4-leaf photosynthesis models. Field studies were conducted in monocultures of S. alterniflora in Virginia, USA. On average, S. alterniflora exhibited lower light saturation values (~1000 μmol m−2 s−1) than observed in other C4 plants. Maximum carbon assimilation rates and stomatal conductance to water vapor diffusion were 36 μmol (CO2) m−2 s−1 and 200 mmol (H2O) m−2 s−1, respectively. Analysis of assimilation-intercellular CO2 and light response relationships were used to determine Arrhenius-type temperature functions for maximum rate of carboxylation
(V
cmax), phosphoenolpyruvate carboxylase activity (V
pmax), and maximum electron transport rate (J
max). Maximum V
cmax values of 105 μmol m−2 s−1 were observed at the leaf temperature of 311 K. Optimum V
pmax values (80.6 μmol m−2 s−1) were observed at the foliage temperature of 308 K. The observed V
pmax values were lower than those in other C4 plants, whereas V
cmax values were higher, and more representative of C3 plants. Optimum J
max values reached 138 μmol (electrons) m−2 s−1 at the foliage temperature of 305 K. In addition, the estimated CO2 compensation points were in the range of C3 or C3–C4 intermediate plants, not those typical of C4 plants. The present results indicate the possibility of a C3–C4 intermediate or C4-like photosynthetic mechanism rather than the expected C4-biochemical pathway in S. alterniflora under field conditions. In a scenario of atmospheric warming and increased atmospheric CO2 concentrations, S. alterniflora will likely respond positively to both changes. Such responses will result in increased S. alterniflora productivity, which is uncharacteristic of C4 plants. 相似文献
12.
A theory of the polarization of counterions bound to a polyion, such as a DNA, in low and high electric field strengths is developed using statistical mechanics of inhomogeneous systems. For low fields, one finds that the polarizability p is (Zq)2 ρ0βL3/(12[1 + Lρ0σ(L, b, ζ, Z, I, ρ0)]J), where σ = ∫10 (λ′ − λ0 {dc(λ − λ′)/dλ}λ = λ0 dλ′J), Z and L are the valence and the length of the polyion, respectively, q is the proton charge, β = 1/kBT, T is the temperature, kB is the Boltzmann constant, I is the ionic strength, λ = x/L and λ0 = x0/L are scaled distances, x0 is a reference point such that the inhomogeneous counterion density at x0 is equal to ρ0—the uniform density in the absence of an electric field E—and c(x) is the direct correlation function of the homogeneous counterion-polyion phase, which includes attractive and repulsive interactions. If Lσ(L, .) is much less than one, then the polarizability is proportional to L3. If the term Lσ(L, .) is much larger than one, the polarizability scales as L2. The induced dipole moment saturates and its value is the same as that of Mandel-Manning theories. The onset of the saturation, however, depends critically on the direct correlation function and hence polyelectrolyte effects. In the formalism, the polarization of the counterions is the equilibrium response to an electric field provided E is less than Esaturated. A dynamical scheme that incorporates the fact that in high fields the bound counterions conduct is discussed. © 1996 John Wiley & Sons, Inc. 相似文献
13.
Temperature response of parameters of a biochemically based model of photosynthesis. II. A review of experimental data 总被引:24,自引:5,他引:19
B. E. Medlyn E. Dreyer D. Ellsworth M. Forstreuter P. C. Harley M. U. F. Kirschbaum X. Le Roux P. Montpied J. Strassemeyer A. Walcroft K. Wang & D. Loustau 《Plant, cell & environment》2002,25(9):1167-1179
The temperature dependence of C3 photosynthesis is known to vary with growth environment and with species. In an attempt to quantify this variability, a commonly used biochemically based photosynthesis model was parameterized from 19 gas exchange studies on tree and crop species. The parameter values obtained described the shape and amplitude of the temperature responses of the maximum rate of Rubisco activity (Vcmax) and the potential rate of electron transport (Jmax). Original data sets were used for this review, as it is shown that derived values of Vcmax and its temperature response depend strongly on assumptions made in derivation. Values of Jmax and Vcmax at 25 °C varied considerably among species but were strongly correlated, with an average Jmax : Vcmax ratio of 1·67. Two species grown in cold climates, however, had lower ratios. In all studies, the Jmax : Vcmax ratio declined strongly with measurement temperature. The relative temperature responses of Jmax and Vcmax were relatively constant among tree species. Activation energies averaged 50 kJ mol?1 for Jmax and 65 kJ mol?1 for Vcmax, and for most species temperature optima averaged 33 °C for Jmax and 40 °C for Vcmax. However, the cold climate tree species had low temperature optima for both Jmax(19 °C) and Vcmax (29 °C), suggesting acclimation of both processes to growth temperature. Crop species had somewhat different temperature responses, with higher activation energies for both Jmax and Vcmax, implying narrower peaks in the temperature response for these species. The results thus suggest that both growth environment and plant type can influence the photosynthetic response to temperature. Based on these results, several suggestions are made to improve modelling of temperature responses. 相似文献
14.
To define the polymorphism and extent of the mouse immunoglobulin kappa (Igk) gene complex, we have analyzed restriction-enzyme digested genomic DNA from 33 inbred strains of mice with labeled DNA probes corresponding to 16 V
x protein groups (1 of them previously undescribed) and the J
k/C
K region (V, variable; J, joining; C, constant). These probes detected between 1 and 25 distinct restriction enzyme fragments (REF) that appeared in up to eight polymorphic patterns, thus defining eight mouse Jgk haplotypes. The investigated portion of the V
A repertoire was estimated to encompass between 60 and 120 discernable V
k gene-containing REFs. In contrast to mouse V
H gene families, several V
k gene families defined by these probes appeared to overlap. This observation has implications for V
k gene analyses by nucleic acid hybridization and raises the possibility that the V
A gene complex is a continuum of related sequences.Abbreviations used in this paper C
constant
- Ig
immunoglobulin
- J
joining
- REF
restriction enzyme fragment
- RFLP
restriction fragment length polymorphism
- V
variable 相似文献
15.
Keith L. Constantine Valentina Goldfarb Michael Wittekind Mark S. Friedrichs James Anthony Shi-Chung Ng Luciano Mueller 《Journal of biomolecular NMR》1993,3(1):41-54
Summary Extensive 1H and 13C assignments have been obtained for the aliphatic resonances of a uniformly 13C-and 15N-labeled recombinant VL domain from the anti-digoxin antibody 26-10. Four-dimensional triple resonance NMR data acquired with the HNCAHA and HN(CO)CAHA pulse sequences [Kay et al. (1992) J. Magn. Reson., 98, 443–450] afforded assignments for the backbone HN, N, H and C resonances. These data confirm and extend HN, N and H assignments derived previously from three-dimensional 1H-15N NMR studies of uniformly 15N-labeled VL domain [Constantine et al. (1992), Biochemistry, 31, 5033–5043]. The identified H and C resonances provided a starting point for assigning the side-chain aliphatic 1H and 13C resonances using three-dimensional HCCH-COSY and HCCH-TOCSY experiments [Clore et al. (1990), Biochemistry, 29, 8172–8184]. The C and C chemical shifts are correlated with the VL domain secondary structure. The extensive set of side-chain assignments obtained will allow a detailed comparison to be made between the solution structure of the isolated VL domain and the X-ray structure of the VL domain within the 26–10 Fab. 相似文献
16.
We hypothesized that inhibition and activation of basolateral to luminal chloride transport mechanisms were associated with
respective decreases and increases in basolateral to luminal water fluxes. The luminal to basolateral (J
W
L→B
) and basolateral to luminal (J
W
B→L
) water fluxes across ovine tracheal epithelia were measured simultaneously. The mean J
W
L→B
(6.5 μl/min/cm2) was larger than J
W
B→L
(6.1 μl/min/cm2). Furosemide reduced J
W
B→L
from 6.0 to 5.6 μl/min/cm2. Diphenylamine-2-carboxylate (DPC) reduced J
W
B→L
from 7.9 to 7.3 μl/min/cm2 and reduced the membrane potential difference by 38%. Furosemide together with DPC decreased J
W
L→B
by 30% and J
W
B→L
by 15%. Norepinephrine increased J
W
B→L
from 4.9 to 6.0 μl/min/cm2. Neuropeptide Y in the presence of norepinephrine decreased J
W
L→B
(6.4 to 5.2 μl/min/cm2) and returned J
W
B→L
to its baseline value. Vasopressin increased J
W
B→L
from 4.1 to 5.1 μl/min/cm2. Endothelin-1 induced a simultaneous increase in J
W
B→L
(7.0 to 7.7 μl/min/cm2) and decrease in J
W
L→B
(7.4 to 6.4 μl/min/cm2); and decreased the membrane resistance. These data indicate that in tracheal epithelia under homeostatic conditions J
W
B→L
has a ∼15% actively coupled component. Consistent with our hypothesis, inhibition and receptor-induced stimulation of chloride
effluxes were associated with decreases and increases in J
W
B→L
, respectively. However, as inhibition of transcellular chloride transport always decreased J
W
L→B
more than J
W
B→L
, reducing transepithelial chloride transport did not result in less water being transported into the airway lumen.
Received: 12 October 1999/Revised: 14 March 2000 相似文献
17.
ZEWEI MIAO MING XU RICHARD G. LATHROP JR. & YUFEI WANG 《Plant, cell & environment》2009,32(2):109-122
A review of the literature revealed that a variety of methods are currently used for fitting net assimilation of CO2–chloroplastic CO2 concentration (A–Cc) curves, resulting in considerable differences in estimating the A–Cc parameters [including maximum ribulose 1·5‐bisphosphate carboxylase/oxygenase (Rubisco) carboxylation rate (Vcmax), potential light saturated electron transport rate (Jmax), leaf dark respiration in the light (Rd), mesophyll conductance (gm) and triose‐phosphate utilization (TPU)]. In this paper, we examined the impacts of fitting methods on the estimations of Vcmax, Jmax, TPU, Rd and gm using grid search and non‐linear fitting techniques. Our results suggested that the fitting methods significantly affected the predictions of Rubisco‐limited (Ac), ribulose 1,5‐bisphosphate‐limited (Aj) and TPU‐limited (Ap) curves and leaf photosynthesis velocities because of the inconsistent estimate of Vcmax, Jmax, TPU, Rd and gm, but they barely influenced the Jmax : Vcmax, Vcmax : Rd and Jmax : TPU ratio. In terms of fitting accuracy, simplicity of fitting procedures and sample size requirement, we recommend to combine grid search and non‐linear techniques to directly and simultaneously fit Vcmax, Jmax, TPU, Rd and gm with the whole A–Cc curve in contrast to the conventional method, which fits Vcmax, Rd or gm first and then solves for Vcmax, Jmax and/or TPU with Vcmax, Rd and/or gm held as constants. 相似文献
18.
Osvaldo Chara Diego E. Pafundo Pablo J. Schwarzbaum 《Bulletin of mathematical biology》2009,71(5):1025-1047
In goldfish hepatocytes, hypotonic exposure leads to cell swelling, followed by a compensatory shrinkage termed RVD. It has
been previously shown that ATP is accumulated in the extracellular medium of swollen cells in a non-linear fashion, and that
extracellular ATP (ATPe) is an essential intermediate to trigger RVD.
Thus, to understand how RVD proceeds in goldfish hepatocytes, we developed two mathematical models accounting for the experimental
ATPe kinetics reported recently by Pafundo et al. in Am. J. Physiol. 294, R220–R233, 2008. Four different equations for ATPe fluxes were built to account for the release of ATP by lytic (J
L
) and nonlytic mechanisms (J
NL
), ATPe diffusion (J
D
), and ATPe consumption by ectonucleotidases (J
V
). Particular focus was given to J
NL
, defined as the product of a time function (J
R
) and a positive feedback mechanism whereby ATPe amplifies J
NL
. Several J
R
functions (Constant, Step, Impulse, Gaussian, and Lognormal) were studied. Models were tested without (model 1) or with (model 2)
diffusion of ATPe.
Mathematical analysis allowed us to get a general expression for each of the models. Subsequently, by using model dependent
fit (simulations) as well as model analysis at infinite time, we observed that:
Finally, the predictive nature of model 1 loaded with a lognormal J
R
was tested by simulating different putative in vivo scenarios where J
V
and J
NL
were varied over ample ranges. 相似文献
– | use of J D does not lead to improvements of the models. |
– | Constant and Step time functions are only applicable when J R =0 (and thus, J NL =0), so that the only source of ATPe would be J L , a result incompatible with experimental data. |
– | use of impulse, Gaussian, and lognormal J R s in the models led to reasonable good fits to experimental data, with the lognormal function in model 1 providing the best option. |
19.
为探讨不同生境典型植物光合特征对主要环境因子的响应,选择Ethier&Livingston、Ellsworth和Sharkey等3种光合生化模型拟合我国西南岩溶与非岩溶区8种典型植物的A-Ci曲线.结果表明,用Ethier&Livingston模型拟合的A-Ci曲线要优于Ellsworth模型和Sharkey模型,拟合... 相似文献
20.
Boonthida Kositsup Pierre Montpied Poonpipope Kasemsap Philippe Thaler Thierry Améglio Erwin Dreyer 《Trees - Structure and Function》2009,23(2):357-365
The aim of this study was to assess the temperature response of photosynthesis in rubber trees (Hevea brasiliensis Müll. Arg.) to provide data for process-based growth modeling, and to test whether photosynthetic capacity and temperature
response of photosynthesis acclimates to changes in ambient temperature. Net CO2 assimilation rate (A) was measured in rubber saplings grown in a nursery or in growth chambers at 18 and 28°C. The temperature response of A was measured from 9 to 45°C and the data were fitted to an empirical model. Photosynthetic capacity (maximal carboxylation
rate, V
cmax, and maximal light driven electron flux, J
max) of plants acclimated to 18 and 28°C were estimated by fitting a biochemical photosynthesis model to the CO2 response curves (A–C
i curves) at six temperatures: 15, 22, 28, 32, 36 and 40°C. The optimal temperature for A (T
opt) was much lower in plants grown at 18°C compared to 28°C and nursery. Net CO2 assimilation rate at optimal temperature (A
opt), V
cmax and J
max at a reference temperature of 25°C (V
cmax25 and J
max25) as well as activation energy of V
cmax and J
max (E
aV and E
aJ) decreased in individuals acclimated to 18°C. The optimal temperature for V
cmax and J
max could not be clearly defined from our response curves, as they always were above 36°C and not far from 40°C. The ratio J
max25/V
cmax25 was larger in plants acclimated to 18°C. Less nitrogen was present and photosynthetic nitrogen use efficiency (V
cmax25/N
a) was smaller in leaves acclimated to 18°C. These results indicate that rubber saplings acclimated their photosynthetic characteristics
in response to growth temperature, and that higher temperatures resulted in an enhanced photosynthetic capacity in the leaves,
as well as larger activation energy for photosynthesis. 相似文献