Vc Max Research Articles

Variation in photosynthetic capacity of Salvia przewalskii along elevational gradients on the eastern Qinghai-Tibetan Plateau, China

Elevational variation in plant growing environment drives diversification of photosynthetic capacity, however, the mechanism behind this reaction is poorly understood. We measured leaf gas exchange, chlorophyll fluorescence, anatomical characteristics, and biochemical traits of Salvia przewalskii at elevations ranging from 2400 m to 3400 m above sea level (a.s.l) on the eastern Qinghai-Tibetan Plateau, China. We found that photosynthetic capacity showed an initial increase and then a decrease with rising elevation, and the best state observed at 2800 m a.s.l. Environmental factors indirectly regulated photosynthetic capacity by affecting stomatal conductance (gs), mesophyll conductance (gm), maximum velocity of carboxylation (Vc max), and maximum capacity for photosynthetic electron transport (Jmax). The average temperature (T) and total precipitation (P) during the growing season had the highest contribution to the variation of photosynthetic capacity of S. przewalskii in subalpine areas, which were 25% and 24%, respectively. Photosynthetic capacity was mainly affected by diffusional limitations (71%–89%), and mesophyll limitation (lm) played a leading role. The variation of gm was attributed to the effects of environmental factors on the volume fraction of intercellular air space (fias), the thickness of cell wall (Tcw), the surface of mesophyll cells and chloroplasts exposed to intercellular airspace (Sm, Sc), and plasma membrane intrinsic protein (PIPs, PIP1, PIP2), independent of carbonic anhydrase (CA). Optimization of leaf tissue structure and adaptive physiological responses enabled plants to efficiently cope with variable climate conditions of high-elevation areas, and the while maintaining high levels of carbon assimilation.

Elevated CO2 concentration enhance carbon and nitrogen metabolism and biomass accumulation of Ormosiahosiei

Elevated CO2 concentrations may inhibit photosynthesis due to nitrogen deficiency, but legumes may be able to overcome this limitation and continue to grow. Our study confirms this conjecture well. First, we placed the two-year-old potted saplings of Ormosia hosiei (O. hosiei) (a leguminous tree species) in the open-top chamber (OTC) with three CO2 concentrations of 400 (CK), 600 (E1), and 800 μmol·mol−1 (E2) to simulate the elevated CO2 concentration environment. After 146 days, the light saturation point (LSP), light compensation point (LCP), apparent quantum efficiency (AQE), and dark respiration rate (Rd) of O. hosiei were increased under increasing CO2 concentration and obtain the maximum ribulose diphosphate (RuBP) carboxylation rate (Vc max) and RuBP regenerated photosynthetic electron transfer rate (Jmax) were also significantly increased under E2 treatment (P < 0.05). This results in a significant increase of the maximum assimilation rate (Amax) under elevated CO2 concentrations. Sucrose phosphate synthase (SPS) activity in sucrose metabolism increased in the leaves, more soluble sugars, starches, and sucrose was produced, but sucrose content only in leaves increased at E2, and more carbon flows to the roots. The activity of the NH4+ assimilating enzymes glutamine synthetase (GS), glutamate synthetase (GOGAT), and glutamate dehydrogenase (GDH) in the leaves of O. hosiei increases under elevated CO2 concentrations to promote nitrogen synthesis that reduces the content of ammonium nitrogen and increases the content of nitrate nitrogen. In addition, under E1 conditions, sucrose synthase (SS), direction of synthesis activity was highest and sucrose invertase (INV) activity was lowest, this means that the balance of C and N metabolism is maintained. While under E2 conditions SS activity decreased and INV activity increased, this increased C/N and nitrogen use efficiency. So, the elevated CO2 concentration promotes the accumulation of O. hosiei biomass, especially in the aboveground part, but did not have a significant effect on the accumulation of root biomass. This means that O. hosiei is able to cope under the elevated CO2 concentration without showing photosynthetic adaptation during the experimental period.

Relationship between Laryngeal Disorders and Respiratory Function in Professional Road Cyclists

Objective: Engaging in outdoor cycling, particularly within cold and arid environments, frequently precipitates dryness in the laryngeal mucosa and induces various supraglottic disorders. Such conditions hold the potential to detrimentally impact respiratory system efficiency. This study principally sought to elucidate the influence of supraglottic and upper airway disorders on the respiratory capacities of road cyclist. Methods and Materials: This investigation encompassed seventy-two professional and elite road cyclists, comprising 22 females and 50 males, with an average age of 22 years and a Body Mass Index (BMI) of 21.95(±0.02) kg/m². Utilizing stroboscopic examinations, supraglottic conditions including Sicca, Tension, Edema, and Gastroesophageal Reflux Disease were assessed. Concurrently, respiratory capacity was evaluated through spirometric tests, encompassing Forced Vital Capacity [FVC], Forced Expiratory Volume in the first second [FEV1], Tidal Volume [VT], Maximum Vital Capacity [VC MAX], Mean Mid-Expiratory Flow [MMEF (FEF25-75)], Peak Expiratory Flow [PEF], and Controlled Mechanical Volume Ventilation [cMVV]. Analysis of Variance (ANOVA) was employed to analyze the relationship between stroboscopic and spirometric findings, additionally exploring correlations between the two. A backward method in regression analysis was used, with Edema (ED), Gastroesophageal Reflux Disease (GERD), Dry Laryngeal Mucosa (Sicca), and Tension (TE) serving as predictor variables against spirometric outcomes. Results: Predominantly, participants exhibited low levels of ED, GERD, Sicca, and TE. No substantial correlation emerged between ED, GERD, TE, and any spirometric indices (p-value &gt; 0.05). However, a notable relationship was observed between Sicca and the MMEF index (p-value &lt; 0.05). Regression analysis revealed significant outcomes for independent variables impacting VT and MEF25, with GERD negatively influencing VT in a statistically significant manner. Likewise, GERD's effect on the MEF25 variable was both negative and significant. Conclusion: This research offers critical insights into the impact of adverse training conditions and laryngeal disorders on respiratory function in cyclists. Addressing these concerns could facilitate considerable enhancements in their performance during training and competitive events.

Effects of light environments within Cinnamomum camphora canopy on leaf functional traits and photosynthetic characteristics.

To explore the adaptive mechanism of leaf photosynthetic capacity in different light environments within Cinnamomum camphora canopy and enhance carbon sequestration, we investigated morphological structures, nutritional and physiological traits and photosynthetic characteristics of leaves in different orientations of C. camphora canopy, southern side in the outer layer (100% full light), southern side in the inner layer (34% full light) and northern side (21% full light). We analyzed the main limitation resulting in down-regulation of photosynthetic capacity in low light environments. Results showed that specific leaf weight, the thickness of lower and upper epidermal cuticle, lower epidermis, palisade tissue as well as cell number and width of palisade tissue, the thickness ratio of palisade to spongy tissue, cell structure closely degree significantly decreased with decreasing light intensity within canopy, opposite to the responses of spongy tissue thickness, cell length-width ratio of palisade tissue, and cell structure loose degree. The contents of leaf carbon, soluble protein, soluble sugar and starch were significantly lower in two low light environments compared with full light, whereas nitrogen content was markedly higher in north side. Low light prominently reduced gas exchange parameters, i.e., net photosynthetic rate (Pn), dark respiration rate, stomatal conductance to CO2(gsc), mesophyll conductance to CO2(gm), total conductance to CO2(gtot), intercellular CO2 concentration (Ci), CO2 concentration at the chloroplast (Cc). Pn was positively correlated with gsc, gm, gtot and Cc. There were no differences in maximum quantum photochemical efficiency, actual quantum photochemical efficiency, photochemical quenching coefficient, maximum rate of Rubisco carboxylation (Vc max) and maximum rate of electron transport (Jmax) among light environments. Vc max and Jmax were positively correlated to Pn. Of the shading-induced limitations to photosynthesis, gm limitation was the most important, and gsc limitation was enhanced with further weakened light intensity while biochemical limitation was rather limited. In summary, the results suggested that full light could improve leaf photosynthetic potential in C. camphora canopy leaves, reduce the effects of gm and gsc limitation on photosynthesis, and consequently enhance carbon assimilation capacity.

The Dynamics of Immature Rubber Photosynthetic Capacities Under Macronutrients Deficiencies

Pará rubber produces natural latex which is essential for the industries. Rubber plant in immature phase is prone to macronutrient deficiencies due to improper management practices in the field and the nature of immature plants that have sensitive physiological responses under stress conditions. The study aimed to assess the effect of macronutrient limitation on immature rubber trees’ photosynthetic capacity and growth. The immature rubber was pot-grown inside the greenhouse with a completely randomized design experiment and nutrient limitations used as the treatments. The treatments consisted of 5 levels, namely, NPK; NP (-K); NK (-P); PK (-N); Control (-NPK). Photosynthetic capacity parameters (Vc max: maximum rate RuBisCO carboxylation, Jmax: RuBP regeneration rate, and TPU: Triose Phosphate Utilization), tree growth (plant height, flush number, leaf number, stem diameter), and leaf macronutrient (N, P, and K) concentrations were periodically measured. Welsch’s test (α = 0.05) continued with Games-Howell pairwise comparison, followed by Pearson’s correlation test and polynomial regressions were performed to describe the nutrient limitation and photosynthetic capacity relationships. Results showed that the leaf nutrient concentration corresponds with the given treatments, even though it was above the critical level for immature rubber. The limitation of N fertilization slightly reduced plant development and growth such as height, leaf number, flush number, relative growth rate, and photosynthetic capacities. However, the P and K limitation effect could not be observed clearly in the observation periods on growth and photosynthetic capacity parameters. Furthermore, the mobility rate of nutrients from the soil to the plants and its translocation inside plant organs played more essential role in plant growth and photosynthetic capacities. Prolonged observation periods on various rubber clones have to be performed to deeply understand the effects of nutrient deficiencies on immature rubber tree morphophysiological activities. HIGHLIGHTS Rubber plant in immature phase have sensitive physiological responses under stress conditions, and it is prone to macronutrient deficiencies due to improper management practices in the field Assessment of macronutrient limitation effect on immature rubber trees’ photosynthetic capacity and growth is essential to understand how the plants strive under the nutrient scarcity and providing a perspective which nutrient is more essential The N fertilization played more essential role compared to P and K, for immature rubber growth and photosynthetic activity GRAPHICAL ABSTRACT

Jeannine Cavender-Bares.

Jeannine Cavender-Bares.

Clinical significance of CC16 and IL-12 in bronchoalveolar lavage fluid of various stages of silicosis.

Identification of novel biomarkers for silicosis could be helpful for disease diagnosis and pathophysiological mechanism exploration. Our study aims to investigate the Clara cell secretory 16-kd protein (CC16) and interleukin-12 (IL-12) levels in bronchoalveolar lavage fluid (BALF) in patients with silicosis at various stages. The enzyme-linked immunosorbent assay (ELISA) double antibody sandwich method was used to determine the CC16 and IL-12 in BALF levels from 79 patients with silicosis of various stages. Correlation analyses were performed between CC16 and IL-12 levels, and lung function and cytological counts in patients with silicosis at various stages. There were no significant differences in the BALF recovery volume, the number of cells, percentages of macrophages and lymphocytes in the alveolar lavage fluid of patients with silicosis in different stages (P>0.05); the percentage of neutrophils in stage I and stage II were higher than the control group (P<0.05) with statistically significant differences. The CC16 in BALF levels in stage I and II silicosis groups lower than the control group and stage III silicosis group with statistically significant differences (P<0.05), whereas CC16 levels in stage II silicosis group are higher than the stage I group (P<0.01). The IL-12 levels were higher than the control group (P<0.01), and the IL-12 levels in stage II and III silicosis group was higher than the stage I silicosis group (P<0.01). With the increase of the length of dust service, the CC16 and IL-12 levels decreased and showed a positive correlation between these indexes (correlation coefficient r=0.559, P<0.01). In addition, CC16 silicosis patient levels were positively correlated with FEV1/FVC and VCmax (r=0.242, 0.257; both P<0.05); IL-12 levels were negatively correlated with FEV1 and VC max (r=-0.250, -0.483; both P<0.05). The CC16 and IL-12 levels may have a specific reference value for the early diagnosis of silicosis and the assessment of lung function.

Examining effects of salt stress on leaf photosynthesis of cotton based on the FvCB model

To understand the responsive mechanism of leaf photosynthesis of cotton to salinity stress, we investigated the effects of salt stress on leaf photosynthetic characteristics of cotton seedlings with the FvCB model under five levels of salt concentration, i.e., 0 (CK), 50, 100, 150 and 200 mmol·L-1. Results showed that, compared with CK, the salt concentrations of 50 and 100 mmol·L-1 increased the maximum carboxylation rate (Vc max) and the maximum electron transport rate (Jmax), while the salt concentrations of 150 and 200 mmol·L-1 significantly decreased Vc max and Jmax. The net photosynthetic rate (Pn), mesophyll conductance (gm) and dark respiration rate (Rd) gradually decreased with the increases of salt concentration. Compared with CK, the salt concentrations of 50 and 100 mmol·L-1 did not affect gm, but significantly decreased Pn and Rd. The salt concentrations of 150 and 200 mmol·L-1 significantly decreased Pn, gm and Rd, which were significantly different from the salt concentrations of 0, 50 and 100 mmol·L-1. Pn of cotton seedlings under different salt concentrations was simulated by the FvCB model. Compared with the results from the FvCB model without considering gm, the FvCB model with gm improved the determination coefficient between the simulated and measured values and decreased the mean absolute error. The salinity threshold of cotton seedlings ranged between 100 and 150 mmol·L-1. With the increases of salt concentration, the limiting factor of leaf photosynthesis changed from mesophyll conductance to impaired components of photosynthetic apparatus. The FvCB model combined gm could improve the accuracy of photosynthesis simulation.

Better pulmonary function is associated with greater handgrip strength in a healthy Chinese Han population

BackgroundHandgrip strength (HGS) has been widely studied in clinical and epidemiological settings, but the relationship between HGS and pulmonary function is still controversial. This study analysed pulmonary function and HGS stratified by sex and age in a healthy Chinese Han population, as well as the associations between HGS and pulmonary function parameters.MethodsHGS was measured by a Jamar dynamometer and pulmonary function was tested using a portable spirometer. Frequencies and variables are presented as percentages and means ± standard deviations, respectively. Chi-square tests were used for comparisons of categorical variables, and Student’s t-tests or Mann–Whitney U-tests were used for continuous variables. Pearson’s correlation coefficients were used to analyse the normally distributed variables, and Spearman correlation coefficients were used to analyse the non-normally distributed variables. Multivariate linear regression models were employed to explore the relationships between HGS and parameters of pulmonary function. The statistical significance was set at p < 0.01.ResultsCross-sectional data were available for 1519 subjects (59.0% females, 57.9 ± 13.3 years old). Males had higher average HGS than females (40.2 vs. 25.0 kg, p < 0.01), as well as better pulmonary function. Both HGS and pulmonary function parameters were significantly inversely correlated with age (r ≤ − 0.30, p < 0.01). The maximum value of vital capacity (VC max), forced expiratory volume in 3 s (FEV 3) and forced vital capacity (FVC) were strongly correlated with HGS among the pulmonary function indices (r = 0.72, 0.70 and 0.69, respectively, p < 0.001). In the multivariate linear regression analysis, HGS and height were positively correlated, while age and pulse pressure were negatively correlated with HGS. In males, the FVC, VC max and FEV3 increased by 0.02 L, 0.023 L and 0.03 L in per 1 kg increase in HGS, respectively. The HGS coefficients for females were smaller than those for males.ConclusionsBoth pulmonary function and HGS were inversely correlated with age, and better pulmonary function was associated with greater handgrip strength.

Association of cathepsin B and cystatin C with an age-related pulmonary subclinical state in a healthy Chinese population.

Background:Cathepsin B (CTSB) and cystatin C (CYSC) are new biomarkers for several physiological and pathological processes as their activities increase with age. The aim of this study was to explore population-level associations between serum CTSB and CYSC with an age-related pulmonary subclinical state.Methods:We examined 401 healthy participants (aged 36–87 years, of which 44.3% were male) in northern Chinese cities. We used a standard spirometer to determine lung function. Serum CTSB and CYSC levels were measured by enzyme-linked immunosorbent assay (ELISA).Results:For all participants, serum CTSB was related to maximum vital capacity (VC MAX), forced vital capacity (FVC), forced expiratory volume in 1 s, peak expiratory flow, forced expiratory flow at 25% of FVC, forced expiratory volume in 3 s (FEV3), and inspiratory vital capacity (VC IN). These associations were lost after full adjustment. CYSC remained significantly associated with inspiratory capacity (IC), breath frequency (BF; p < 0.001), minute ventilation (MV), the ratio of FEV3 and FVC (FEV3%FVC), and expiratory reserve volume (p < 0.05) after adjusting for all other possible confounders. In males, serum CYSC levels exhibited significant and independent associations with FVC, FEV3 (p < 0.05), and IC (p < 0.001) and serum CTSB levels exhibited significant and independent associations with BF (p < 0.05).Conclusions:Our results confirmed serum CYSC concentration associations with an age-related lung function in healthy people. However, the association between serum CTSB and lung function was not well confirmed. Serum measurements of CYSC may provide valuable predictors of pulmonary function in healthy people, especially healthy elderly adults.The reviews of this paper are available via the supplemental material section.

Study of the association of distribution pattern of genotypes of C/A polymorphism of COL1A1_1 collagen gene (RS1107946) with indicators of external breathing in children with bronchial asthma

Purpose. The study of the distribution patterns of allelic genes and genotypes of the C/A polymorphism of the collagen COL1A1_1 gene (rs1107946) in children with bronchial asthma, taking into account the indicators of external respiration function. Materials and methods. Molecular-genetic study to determine the C/A polymorphism of the collagen COL1A1_1 gene (rs1107946) was conducted in 125 children from 6 to 18 years, 100 of them with bronchial asthma who were hospitalized in the Allergic Department of the Municipal Non-Profit Enterprise “City Children Hospital No 5 of Zaporizhzhia City Council” and 25 healthy children (control group). There were no differences in age and sex in the comparison groups (P > 0.05).Genotype determination was performed by polymerase chain reaction method according to the instruction (Applied Biosystems, USA) using the samples of total DNA received from whole venous blood using SNP-Screen reagents (manufactured by “Syntol”) on amplifier CFX96TM Real-Time PCR Detection Systems (“Bio-Rad laboratories, Inc.”, USA). The ventilation function of the lungs was studied by conducting a spirometric study on a computer spirograph “PULMOREM” TU U 33.1-02066769-005-2002 (Kharkiv, Ukraine). To compare the frequencies of alleles and genotypes in different groups, the non-parametric statistical method “2 × 2 Table”, the Chi-square (df = 1) was used. Medians and interquartile intervals were also calculated, the two independent groups were compared by the Mann-Whitney criterion, the χ 2 criterion. Non-parametric statistics methods for the licensed software package Statistica for Windows 6.1.RU, serial number АХХR712D833214SAN5, were used to process the obtained study data. Results. Molecular-genetic study of distribution patterns of allelic genes of the C/A polymorphism of the COL1A1_1 collagen gene (rs1107946) in patients with bronchial asthma and in practically healthy children, showed that the allele C was registered with a frequency of 69.5 % and 84.0 %, allele A – 30.5 % and 16.0 %; dominant genotype C/C – 58 % and 76 %; heterozygous genotype C/A – 23 % and 16 %; homozygous genotype A/A – 19 % and 8 %, respectively. Children with bronchial asthma with genotype A/A had significantly lower FVC values up to 2.32 (1.55; 3.29), VC max up to 1.69 (1.40; 2.98), FEV 1 up to 1.82 (1.43; 2.98), with genotype C/C – MEF 75 up to 2.34 (1.87; 3.14) when compared with patients with heterozygous genotype A/C, and very low rates of FVC were recorded in 68.75 % of children with bronchial asthma with the A/A genotype against 30.77 % of patients with the A/C genotype and 36.17 % with the C/C genotype (P < 0.05). Conclusion. Homozygous genotype A/A of C/A polymorphism of the COL1A1_1 collagen gene (rs1107946), was associated with more pronounced disorders of ventilatory function of lungs with obstructive breathing type due to impaired collagen formation in the bronchi, which may have prognostic significance both for early diagnosis and prediction of clinical course severity of this disease as well as for prevention and treatment of bronchial obstruction in patients.

The effects of sesame/peanut intercropping on photosynthetic fluorescence characteristics in functional leaf of sesame.

To unravel functional leaf photosynthetic mechanisms underlying enhanced yield of sesame in sesame/peanut intercropping, a field experiment was carried out in 2017 and 2018 with four treatments including (1) three-row sesame intercropped with six-row peanut (IC 3:6), (2) two-row sesame intercropped with four-row peanut (IC 2:4), (3) sole cropped sesame (SS), and (4) sole cropped peanut (SP). We measured the parameters of gas exchange, characteristics of photosynthetic response curve to light and CO2, and characteristics of chlorophyll rapid fluorescence induction kinetic curves of the functional leaves of sesame. The results showed that the partial land equivalent ratio of intercropped sesame was greater than 1/3. The light saturation point (Isat), maxi-mum net photosynthetic rate (Pn max), maximum electron transport rate (Jmax), triose phosphate utilization rate (TPU), maximum carboxylation rate of Rubisco (Vc max) were increased significantly under intercropping. Further, absorption energy flux per CS (ABS/CSo), trapping energy flux per CS (TRo/CSo), number of active reaction centers per CS (RC/CSm), and electron transport flux per CS (ETo/CSo) in intercropped treatments were enhanced compared to that under sesame monoculture. However, the ratio between variable fluorescence Fk to amplitude Fj-Fo (Wk) and ratio between variable fluorescence Fj to amplitude Fp-Fo (Vj) in functional leaves of intercropped sesame were significantly decreased. The efficiency of converting light energy into electricity of PS2 reaction center (Ψo), electron transfer efficiency from PS2 to end acceptor of PS1 (ΨRo), electron transfer efficiency of the electron transport chain (δR), PS1 photochemical activity, and the coordination between PS2 and PS1 in functional leaves of intercropped sesame were increased. The net photosynthetic rate (Pn), stomatal conductance (gs), transpiration rate (Tr), Pn max, Jmax, Vc max, TPU, Ψo, ΨRo and δR were significantly higher in IC 3:6 than those in IC 2:4. We conclude that intercropping improves net photosynthetic rate and yield of sesame by increasing light absorption, electronic transmission, activity of PS2 donator/receptor sides, and CO2 fixation, with stronger effects in IC 3:6 than IC 2:4.

Increased atmospheric CO2 changes the photosynthetic responses of Acrocomia aculeata (Arecaceae) to drought

Water availability is the main factor that explains current patterns of palm abundance. However, the interaction between water stress and increasing atmospheric CO2 concentrations caused by climatic change and its effects on palm physiology remain poorly known. Macauba palm is a widespread Neotropical species commonly found in ecosystems subjected to seasonal drought and has potential use in oil production. The present work investigated the influence of increased CO2 concentrations on photosynthetic responses to drought in macauba palm plants. Exposure to increased CO2 concentrations led to up-regulation of photosynthesis through higher stomatal conductance and improved light and water use efficiency. Macauba palm plants under water stress, irrespective of CO2 concentration, were able to maintain constant levels of proline and chlorophyll, while preventing oxidative damage. Plants grown at higher CO2 concentrations were more capable of recovering from drought due to higher Rubisco carboxylation rate (Vc max) and electron transport rate (J max), which prevented a reduction in total dry mass at the end of the stress period. Stomatal control of photosynthesis, coupled with the prevention of severe damage under stress, would allow efficient biomass production by the macauba palm under future scenarios of climate change.

In-situ measurement of photosynthetic characteristics of dominant tree species based on canopy crane in a Korean pine broad-leaved forest in Changbai Mountain, northeastern China.

To better understand the eco-physiological characteristics of dominant tree species in Korean pine broad-leaved forests, and to provide fundamental data for modelling and predicting carbon dynamics of forest ecosystems, we measured leaf CO2 assimilation rate versus intercellular CO2 concentration curves of four canopy dominant tree species in a Korean pine broad-leaved forest, in situ, for the first time, using a canopy crane in the Changbai Mountain Forest Ecosystem Research Station. Several important photosynthetic parameters were fitted with the FvCB model. Photosynthe-tic rate (A), maximum carboxylation rate (Vc max) and stomatal conductance (gs) were lowest in Pinus koraiensis (Pk), while stomatal limitation on photosynthesis (Ls) was highest in Pk. There were significant variations of photosynthetic characteristics among the three broad-leaved tree species [i.e., Fraxinus mandshurica (Fm), Quercus mongolica (Qm) and Tilia amurensis (Ta)]. The rank of tree species with respect to area-based Vc max was: Fm (83.2 μmol·m-2·s-1) and Qm (89.3 μmol·m-2·s-1) > Ta (68.4 μmol·m-2·s-1) and Pk (68.8 μmol·m-2·s-1) (P<0.05), and their rank with respect to mass-based Vc max was: Fm (1.36 μmol·g-1·s-1) > Qm (1.03 μmol·g-1·s-1) > Ta (0.90 μmol·g-1·s-1) > Pk (0.42 μmol·g-1·s-1) (P<0.05). From July to September, A value significantly declined in Fm and Qm, but remained stable in Ta and Pk. By contrast, Vc max significantly decreased in all tree species from July to September. Our results indicated that seasonal variation of Vcmax should be taken into consideration in the modelling and predicting of forest ecosystem carbon dynamics in northeastern China.

Parameterized and approximation complexity of Partial VC Dimension

We introduce the problem Partial VC Dimension that asks, given a hypergraph H=(X,E) and integers k and ℓ, whether one can select a set C⊆X of k vertices of H such that the set {e∩C,e∈E} of distinct hyperedge-intersections with C has size at least ℓ. The sets e∩C define equivalence classes over E. Partial VC Dimension is a generalization of VC Dimension, which corresponds to the case ℓ=2k, and of Distinguishing Transversal, which corresponds to the case ℓ=|E| (the latter is also known as Test Cover in the dual hypergraph). We also introduce the associated fixed-cardinality maximization problem Max Partial VC Dimension that aims at maximizing the number of equivalence classes induced by a solution set of k vertices. We study the algorithmic complexity of Partial VC Dimension and Max Partial VC Dimension both on general hypergraphs and on more restricted instances, in particular, neighborhood hypergraphs of graphs.

Clinical significance of interleukin-6 and -8 in patients with chronic periodontal disease and acute exacerbation of chronic obstructive pulmonary disease

Objective: To investigate the serum levels of interleukin (IL)-6 and -8 in patients with chronic periodontal disease and acute exacerbation of chronic obstructive pulmonary disease (AECOPD) and the possible relationship between IL-6 and IL-8 with two diseases. Methods: A total of 40 cases of healthy subjects (control group 1) from graduate school of Anhui Medical University, and 120 cases (40 cases in each of the 3 groups) of eligible patients were collected, of which 40 were patients with chronic periodontal disease and AECOPD (experimental group) from Department of Respiratory Medicine, The First Affiliated Hospital of Anhui Medical University and Anhui NO.2 Provincial People's Hospital, 40 were patients with chronic periodontal disease (control group 2) from Department of Stomatology, The First Affiliated Hospital of Anhui Medical University, 40 were patients with AECOPD (control group 3) from Department of Respiratory Medicine, The First Affiliated Hospital of Anhui Medical University. The clinical indicators of all subjects were collected, including tooth mobility degree, probing depth (PD), bleeding index (BI), attachment level (AL), vital capacity max (VC Max), forced expiratory volume in first second (FEV1) and forced expiratory volume in first second to forced vital capacity (FEV1/FVC) ratio. Enzyme linked immunosorbent assay (ELISA) was used to detect the serum levels of IL-6 and IL-8 in the subjects of four groups. Results: The attachment levels had no significant differences between experimental group and control group 2 (P>0.05). The pulmonary function indices of experimental group including VC MAX% pre[(56.1±11.1)%], FEV1 %pre [(44.8±12.2)%], FEV1/FVC(%) [(56.8±11.4)%] were significantly different from those in control group 3 [(66.3±10.1)%, (53.0±10.4)%, (66.5±8.2)%, respectively]. The IL-6 levels of experimental group, control groups 1, 2 and 3 were (14.4±3.9), (2.1±1.1), (4.8±1.9) and (8.6±1.4) ng/L, respectively. And the IL-8 levels were (35.3±33.3), (4.8±1.7), (9.7±3.3) and (15.6±9.6) ng/L. In experimental group the IL-6 and IL-8 levels were significantly higher than those in control groups 1, 2, and 3 (P<0.01). In control group 2 and 3 the IL-6 and IL-8 levels were significantly higher than that in control group 1 (P< 0.01). Conclusions: The IL-6 and IL-8 levels of experimental group were significantly increased. IL-6 and IL-8 may be associated with the development of periodontal disease and AECOPD closely.

Effects of light intensity on photosynthetic capacity and light energy allocation in Panax notoginseng.

To explore the effects of light intensity on photosynthetic characteristics and light adaptation of the shade-demanding species Panax notoginseng, the responses of photosynthesis to photosynthetic photon flux density, CO2 and sunflecks in the two-year-old Panax notoginseng were investigated under different levels of light intensity (29.8%, 9.6%, 5.0%, 1.4% and 0.2% of full sunlight). Meanwhile, chlorophyll a fluorescence parameter and light energy partitioning were also recorded and calculated in the responsive process. P. notoginseng grown under 29.8% full sunlight (FL) had a lower apparent quantum yield (AQY), potential photochemical quantum yield (Fv/Fm) and potential photochemical activity (Fv/Fo), however, it had a higher maximum net photosynthetic rate (Pn max), maximum electron transport rate (Jmax), F/Fm', electron transport rate (ETR), photochemical quenching (qP) and the proportion of light energy allocated to photochemistry dissipation (ΦPS2), but the non-photochemical quenching (NPQ) was not the highest. There were no significant differences in Pn max, light compensation point (LCP), light saturation point (LSP), dark respiration rate (Rd) among 9.6%FL and 5.0% FL treatments, but these treatments had relatively higher values of NPQ, AQY, carboxylation efficiency (CE), maximum carboxylation rate (Vc max), Fv/Fm and Fv/Fo. In addition, the Pn max, CE, Vc max, Jmax, ETR,F/Fm', qP, NPQ and ΦPSII decreased with the decrease in light intensity from 5.0%FL to 0.2%FL, and the proportion of light energy allocated to fluorescent dissipation (Φf,d) were increased. Under 500 μmol·m-2·s-1 light-flecks inducting, the ΦPSⅡof P. notoginseng increased slowly with the extension of time except for the treatment of less than 5.0%FL, and under the circumstance of 1.4%FL and 0.2%FL, ΦPSⅡreached significantly a perfect result, moreover, Φf,dincreased rapidly. These results suggested that the enhancement in photosynthetic electron transport to use the light energy and the moderate photoinhibition of PS2 might avoid the irreversible oxidative damage of photosynthetic organization in P. notoginseng under high levels of light intensity. Moderate shading was beneficial to maintain its higher non-photochemical quenching ability. However, its photosynthetic capacity depressed and the proportion of light energy allocated to non-photochemical pathway increased obviously in excessive shading, and it easily caused a light oxidative damage.

Photo-physiological and photo-biochemical characteristics of several herbaceous and woody species based on FvCB model

To explore the photosynthetic capacity and the leaf photosynthetic apparatus for plants with different life forms, CO2 response curves of 7 woody species and 4 herbaceous species were fitted by the modified rectangular hyperbolic model and the FvCB model, and the photosynthetic parameters, including maximum net photosynthetic rate (Pn max), maximal Rubisco carboxylation rate (Vc max), maximal electron transport rate (Jmax), day respiration (Rd), and mesophyll resistance to CO2 transport (rm), were compared among different woody species, among different herbaceous species, and between woody and herbaceous life-forms, respectively. The results showed Pn max of seven woody species descended in the order of Sapium sebiferum and Boehmeria nivea ＞ Machilus pingii and Pittosporum tobira ＞ Cyclobalanopsis glauca, Castanopsis sclerophylla, and Quercus nuttallii. Vc max of S. sebiferum, B. nivea, M. pingii, and P. tobira was significantly higher than that of C. glauca and C. sclerophylla. Jmax of woody species was in descending order as S. sebiferum ＞ B. nivea and P. tobira ＞ Q. nuttallii, C. sclerophylla, and C. glauca. rm of M. pingii and C. sclerophylla was higher than that of S. sebiferum, P. tobira and B. nivea. Pn max of Phytolacca acinosa was significantly higher than that of Ageratum conyzoides and Achyranthes aspera. There was no significant difference in Vc max among 4 herbaceous species. Jmax of P. acinosa was higher than that of A. conyzoides. rm of S. nigrum and A. aspera was higher than that of A. conyzoides. Rd of P. acinosa was higher than that of A. conyzoides and A. aspera. The photosynthetic parameters (Pn max, Vc max, Jmax and rm) of woody species were significantly higher than those of herbaceous species, but no significant difference was found in Rd between woody and herbaceous species. In conclusion, the difference in photosynthetic capacity among different species and between the two plant life-forms resulted from the difference in Rubisco carboxylation capacity, electron transport capacity, and mesophyll resistance among these species.

Effects of maize/peanut intercropping row ratio and phosphate fertilizer on photosynthetic characteristics of maize.

To get better insight into the photosynthetic mechanism of plant adaptation to strong light in intercropped maize, a field trial was carried out in 2014-2015 to investigate the effects of maize/peanut intercropping row ratio and phosphate fertilizer on diurnal variation in light intensity of maize canopy, SPAD value, and the curves of photosynthetic response of net photosynthetic rate (Pn) to photon flux density (PFD) and to CO2 of functional leaves. The field trial comprised 2 rows maize intercropped with 2 rows peanut (2:2, R1), 2 rows maize intercropped with 4 rows peanut (2:4, R2) and 2 rows maize intercropped with 8 rows peanut (2:8, R3). Results showed that the light intensity of intercropped maize canopy was R3>R2>R1. From pre-tasselling to filling stage, the SPAD value, apparent quantum efficiency (AQY), light compensation point (LCP), light saturation point (LSP), maximum net photosynthetic rate, carboxylation efficiency (CE), maximum electron transfer rate (Jmax), triose phosphate utilization (TPU), stomatal conductance (gs), transpiration rate (Tr) and Pn in ear leaves of intercropped maize were R3>R2>R1, but the intercellular CO2 concentration (Ci) was R1>R2>R3. At dough stage, the AQY, LSPn, gs, CE, Jmax and TPU in ear lea-ves of intercropped maize in R3 intercropping system were lower than those in R2 intercropping system. The photosynthetic indices, such as AQY, LSPn, CE, Vc max, Jmax and TPU were increased by phosphate fertilizer application. These results suggested that the key mechanisms that enhanced strong light utilization ability of intercropped maize were attributed to gradual improvement in gs, AQY, CE, Vc max, Jmax and TPU of ear leaves with increasing light intensity, however, beyond a certain light intensity, intercropped maize leaves were prone to premature senescence. Nonetheless, phosphate fertilizer could improve light utilization and delay leaf senescence in intercropped maize.

Collaborative application of BEPS at different time steps.

BEPSHourly is committed to simulate the ecological and physiological process of vegetation at hourly time steps, and is often applied to analyze the diurnal change of gross primary productivity (GPP), net primary productivity (NPP) at site scale because of its more complex model structure and time-consuming solving process. However, daily photosynthetic rate calculation in BEPSDaily model is simpler and less time-consuming, not involving many iterative processes. It is suitable for simulating the regional primary productivity and analyzing the spatial distribution of regional carbon sources and sinks. According to the characteristics and applicability of BEPSDaily and BEPSHourly models, this paper proposed a method of collaborative application of BEPS at daily and hourly time steps. Firstly, BEPSHourly was used to optimize the main photosynthetic parameters: the maximum rate of carboxylation (Vc max) and the maximum rate of photosynthetic electron transport (Jmax) at site scale, and then the two optimized parameters were introduced into BEPSDaily model to estimate regional NPP at regional scale. The results showed that optimization of the main photosynthesis parameters based on the flux data could improve the simulate ability of the model. The primary productivity of different forest types in descending order was deciduous broad-leaved forest, mixed forest, coniferous forest in 2011. The collaborative application of carbon cycle models at different steps proposed in this study could effectively optimize the main photosynthesis parameters Vc max and Jmax, simulate the monthly averaged diurnal GPP, NPP, calculate the regional NPP, and analyze the spatial distribution of regional carbon sources and sinks.