The application of exogenous 24-epibrassinolide promotes Brassinosteroids intracellular signalling in cucumber, which leads to differentially expressed proteins that participate in different life process to relieve Ca(NO3)2damage.
Abstract
NO3? and Ca2+ are the main anion and cation of soil secondary salinization during greenhouse cultivation. Brassinosteroids (BRs), steroidal phytohormones, regulate various important physiological and developmental processes and are used against abiotic stress. A two-dimensional electrophoresis gel coupled with MALDI-TOF/TOF MS was performed to investigate the effects of exogenous 24-epibrassinolide (EBL) on proteomic changes in cucumber seedling roots under Ca(NO3)2 stress. A total of 80 differentially accumulated protein spots in response to stress and/or exogenous EBL were identified and grouped into different categories of biological processes according to Gene Ontology. Under Ca(NO3)2 stress, proteins related to nitrogen metabolism and lignin biosynthesis were induced, while those related to cytoskeleton organization and cell-wall neutral sugar metabolism were inhibited. However, the accumulation of abundant proteins involved in protein modification and degradation, defence mechanisms against antioxidation and detoxification and lignin biosynthesis by exogenous EBL might play important roles in salt tolerance. Real-time quantitative PCR was performed to investigate BR signalling. BR signalling was induced intracellularly under Ca(NO3)2 stress. Exogenous EBL can alleviate the root indices, effectively reduce the Ca2+ content and increase the K+ content in cucumber roots under Ca(NO3)2 stress. This study revealed the differentially expressed proteins and BR signalling-associated mRNAs induced by EBL in cucumber seedling roots under Ca(NO3)2 stress, providing a better understanding of EBL-induced salt resistance in cucumber seedlings. The mechanism for alleviation provides valuable insight into improving Ca(NO3)2 stress tolerance of other horticultural plants.
To improve xanthan gum productivity, a strategy of adding hydrogen peroxide (H2O2) was studied. The method could intensify oxygen supply through degradation of H2O2 to oxygen (O2). In shake flask testing, the xanthan gum yield reached 2.8% (improved by 39.4%) when adding 12.5 mM H2O2 after 24 h of fermentation. In fermentor testing, it was obvious that the oxygen conditions varied with the H2O2 addition time. Eventually, gum yield of 4.2% (w/w) was achieved (increased by 27.3%). Compared with the method of intense
mixing and increasing the air flow rate, adding H2O2 to improve the dissolved oxygen concentration was more effective and much better. Moreover, addition of H2O2 improved the quality of xanthan gum; the pyruvate content of xanthan was 4.4% (w/w), higher than that of the control (3.2%). 相似文献
PurposePulse oximetry is routinely used to continuously and non-invasively monitor arterial oxygen saturation (SaO2). When oxygen saturation by pulse oximeter (SpO2) overestimates SaO2, hypoxemia may be overlooked. We compared the SpO2 - SaO2 differences among three pulse oximeters in patients with chronic thromboembolic pulmonary hypertension (CTEPH) who spent their daily lives in a poor oxygen state.ResultThe root mean square of each pulse oximeter was 1.79 (OLV-3100), 1.64 (N-BS), and 2.50 (Masimo Radical). The mean bias (SpO2 - SaO2) for the 90%–95% saturation range was significantly higher for Masimo Radical (0.19 +/- 1.78% [OLV-3100], 0.18 +/- 1.63% [N-BS], and 1.61 +/- 1.91% [Masimo Radical]; p<0.0001). The optimal SpO2 value to detect hypoxemia (SaO2≦90%) was 89% for OLV-3100, 90% for N-BS, and 92% for Masimo Radical.ConclusionWe found that the biases and precision with which to detect hypoxemia differed among the three pulse oximeters. To avoid hypoxemia, the optimal SpO2 should be determined for each pulse oximeter. 相似文献
Nitromethane (NM, CH3NO2) is a widely studied energetic material, and its decomposition mechanism attracts great interest. In this work, bimolecular reactions between NO2 and nine intermediates generated during the decomposition of NM were investigated by computational chemistry methods. The mechanisms of the reactions were analyzed. The results revealed that these reactions possess small barriers and can easily occur, so they may be responsible for NO2 loss during the decomposition of NM. 相似文献
Hydrogen peroxide (H2O2), an active oxygen species, is widely generated in many biological systems and mediates various physiological and biochemical
processes in plants. In the present study, we present a signaling network involving H2O2, nitric oxide (NO), calcium (Ca2+), cyclic guanosine monophosphate (cGMP), and the mitogen-activated protein kinase (MAPK) cascade during adventitious rooting
in mung bean seedlings. Both exogenous H2O2 and the NO donor sodium nitroprussiate were capable of promoting the formation and development of adventitious roots. H2O2 and NO signaling pathways were elicited in parallel in auxin-induced adventitious rooting. Cytosolic Ca2+ was required for adventitious rooting, and Ca2+ served as a downstream component of H2O2, as well as cGMP or MAPK, signaling cascades. cGMP and MAPK cascades function downstream of H2O2 signaling and depend on auxin responses in adventitious root signaling processes. 相似文献
Wastewater treatment plants are known to be important point sources for nitrous oxide (N2O) in the anthropogenic N cycle. Biofilm based treatment systems have gained increasing popularity in the treatment of wastewater, but the mechanisms and controls of N2O formation are not fully understood. Here, we review functional groups of microorganism involved in nitrogen (N) transformations during wastewater treatment, with emphasis on potential mechanism of N2O production in biofilms. Biofilms used in wastewater treatment typically harbour aerobic and anaerobic zones, mediating close interactions between different groups of N transforming organisms. Current models of mass transfer and biomass interactions in biofilms are discussed to illustrate the complex regulation of N2O production. Ammonia oxidizing bacteria (AOB) are the prime source for N2O in aerobic zones, while heterotrophic denitrifiers dominate N2O production in anoxic zones. Nitrosative stress ensuing from accumulation of NO2? during partial nitrification or denitrification seems to be one of the most critical factors for enhanced N2O formation. In AOB, N2O production is coupled to nitrifier denitrification triggered by nitrosative stress, low O2 tension or low pH. Chemical N2O production from AOB intermediates (NH2OH, HNO, NO) released during high NH3 turnover seems to be limited to surface-near AOB clusters, since diffusive mass transport resistance for O2 slows down NH3 oxidation rates in deeper biofilm layers. The proportion of N2O among gaseous intermediates (NO, N2O, N2) in heterotrophic denitrification increases when NO or nitrous acid (HNO2) accumulates because of increasing NO2?, or when transient oxygen intrusion impairs complete denitrification. Limited electron donor availability due to mass transport limitation of organic substrates into anoxic biofilm zones is another important factor supporting high N2O/N2 ratios in heterotrophic denitrifiers. Biofilms accommodating Anammox bacteria release less N2O, because Anammox bacteria have no known N2O producing metabolism and reduce NO2? to N2, thereby lowering nitrosative stress to AOB and heterotrophs. 相似文献
A new method of the chlorophyll (Chl) a fluorescence quenching analysis is described, which allows the calculation of values of (at least) three components of the
non-photochemical quenching of the variable Chl a fluorescence (qN) using a non-linear regression of a multi-exponential function within experimental data. Formulae for coefficients of the
“energy”-dependent (ΔpH-dependent) quenching (qE), the state-transition quenching (qT) and the photo/inhibitory quenching (qI) of Chl a fluorescence were found on the basis of three assumptions: (i) the dark relaxation kinetics of qN, as well as of all its components, is of an exponential nature, (ii) the superposition principle is valid for individual
Chl a fluorescence quenching processes and (iii) the same reference fluorescence level (namely the maximum variable Chl a fluorescence yield in the dark-adapted state, FV) is used to define both qN and its components. All definitions as well as the algorithms for analytical recognition of the qN components are theoretically clarified and experimentally tested. The described theory results in a rather simple equation
allowing to compute values for all qN components (qE, qT, qI) as well as the half-times of relaxation (τ1/2) of corresponding quenching processes. It is demonstrated that under the above assumptions it holds: qN = qE + qT + qI. The theoretically derived equations are tested, and the results obtained are discussed for non-stressed and stressed photosynthetically
active samples. Semi-empirical formulae for a fast estimation of values of the qN components from experimental data are also given. 相似文献
A horizontal biotrickling filter (HBTF) was used to inoculate autotrophic sulfide-oxidizing and ammonia-oxidizing microbial
consortiums over H2S-exhausted carbon for co-treating H2S and NH3 waste gas in a long-term operation. In this study, several aspects (i.e., pH change, shock loading and starvation) of the
dynamic behavior of the HBTF were investigated. The metabolic products of N and S bearing species in recycling liquid and
biological activities of the biofilm were analyzed to explain the observed phenomena and further explore the fundamentals
behind. In the pH range of 4–8.5, although the removal efficiencies of H2S and NH3 remained 96–98% and 100%, respectively, the metabolic products demonstrated different removal mechanisms and pathways. NH4-N and NO2/NO3-N were dominated at pH ≤6 and ≥7, respectively, indicating the differentiated contributions from physical/chemical adsorption
and bio-oxidation. Moreover, the HBTF demonstrated a good dynamic stability to withstand shock loadings by recovering immediately
to the original. During shock loading, only 15.4% and 17.9% of captured H2S and NH3 was biodegraded, respectively. After 2, 11, and 48 days of starvation, the HBTF system reached a full performance within
reasonable re-startup times (2–80 h), possibly due to the consumption of reduced S and N species in biomass or activated carbon
thus converted into SO4-S and NO3-N during starvation period. The results helped to understand the fundamental knowledge by revealing the effects of pH and
transient loadings linked with individual removal mechanism for H2S and NH3 co-treatment in different conditions. 相似文献
In many coastal areas of South-East Asia, attempts have been made to revive coastal ecosystem by initiating projects that
encourage planting of mangrove trees. Compared to the terrestrial trees, mangrove trees possess a higher carbon fixation capacity.
It becomes a very significant option for clean development mechanism (CDM) program. However, a reliable method to estimate
CO2 fixation capacity of mangrove trees has not been established. Acknowledging the above fact, we decided to set up an estimation
method for the CDM program, using gas exchange analysis to estimate mangrove productivity, we put into consideration the net
CO2 fixation of reforested Kandelia candel (5-, 10-, and 15-year-old stand). This was estimated by gas exchange analysis and growth curve analysis. In growth curve
analysis, we drew a growth curve of a single stand using data of above- and below-ground biomass. In the gas exchange analysis,
we calculated CO2 fixation capacity by (1) measuring respiration rate of each organ of stand and calculating respiratory CO2 emission from above- to below-ground biomass. (2) Measuring the single-leaf photosynthetic rate in response to light intensity
and calculating the photosynthetic CO2 absorption. (3) We also developed a model for the diurnal changes in temperature, and monthly averages based on one-day estimation
of CO2 absorption and emission, which we corrected by this model in order to estimate the net CO2 fixation capacity in response to temperature. Comparing the biomass accumulation of the two methods constructed for the same
forest, the above-ground biomass accumulation of 10-year-old forest (34.3 ton ha−1 yr−1) estimated by gas exchange analysis was closely compared to those of growth curve analysis (26.6 ton ha−1 yr−1), suggesting that the gas exchange analysis was capable of estimating mangrove productivity. The validity of the estimated
CO2 fixation capacity by the gas exchange analysis and the growth curve analysis was also discussed. 相似文献
Reactive oxygen species (ROS), namely superoxide radical (O2−) and hydrogen peroxide (H2O2) are generated when plant tissues endure a variety of environmental stresses, including light stress. The extremely short
life times of ROS makes the study of their production in planta very difficult. The use of ROS-specific tracer dyes, 3-3′
diaminobenzidine and nitroblue tetrazolium, together with high-resolution imaging provides the opportunity to identify sites
of photooxidative stress response by ROS accumulation. This technique was applied to grapevine during the first 7 days after
transfer from in vitro to ex vitro under an irradiance 4-fold higher than in vitro. ROS accumulation was detected in the first
days of analysis, which gradually decreased to levels comparable to greenhouse leaves. O2− was uniformly distributed while H2O2 accumulated preferentially in veins, wounds and stomatal guard and surrounding cells. To evaluate the role of H2O2 in stomatal functioning and its crosstalk with abscisic acid (ABA) we focused on the percentage of coloured structures, stomatal
aperture and ABA concentration. We propose that the high H2O2 level triggered by increased light is responsible for the activation of a signalling pathway over stomatal cells, in a process
apparently irrespective of ABA regulation prior to root protrusion. This could explain the gain of function of a low yet consistent
percentage of stomatal cells, essential for plant survival during the ontogenic period in analysis. 相似文献
The oxygen saturation (StO2) and total hemoglobin volume in cutaneous blood are closely related to cutaneous metabolism and are important factors in
determining the skin color. Most conventional apparatuses for the measurement of cutaneous metabolism have been designed to
evaluate qualitative changes in the oxyhemoglobin volume, deoxyhemoglobin volume, and their sum (total Hb volume) relative
to their baseline values. In this study, we developed an instrument for non-invasive evaluation of individual and regional
differences in StO2 and Hb volume, a system unaffected by melanin (Kao PSA system model III), and examined the validity of its application. First,
changes in StO2 and total Hb volume in the antebrachial region during venous occlusion and devascularization by compression of the brachial
region were evaluated. Changes in total Hb volume following venous occlusion were found to reflect the cutaneous blood flow.
Also, StO2 was considered to reflect the state of oxygen consumption by the skin, because it was markedly reduced during devascularization.
Next, the subjects were exposed to graded hypobaric conditions, and the relationships among StO2, arterial blood oxygen saturation (SaO2), and venous blood oxygen saturation (SvO2) were studied. StO2 showed significant positive correlations with SaO2 (r=0.811, P<0.001) and SvO2 (r=0.966, P<0.001), and its correlation with SvO2 was particularly strong. Therefore, StO2 was found to be closely dependent on SvO2. Lastly, StO2, total Hb volume, and other parameters were measured in healthy women (aged 20–69 years), and their regional differences
and age- associated changes were evaluated. These regional differences (angle of mouth > cheek > forehead) and age-associated
decreases in StO2 are considered to be caused by the age-associated decreases in the cutaneous blood flow.
Received: 21 May 1999 / Revised: 19 November 1999 / Accepted: 24 November 1999 相似文献
Mutation of Sip1 plays a key role in pathogenesis of the Mowat–Wilson syndrome characterized by the presence of pronounced epileptic signs in patients. As a rule, neurodegenerative processes are accompanied by hypoxic phenomena, glutamate toxicity, and death of nerve cells. The molecular mechanisms underlying these phenomena are multifaceted and complex. Hypoxia causes the leakage of glutamate and other neurotransmitters and thus activates glutamate receptors and channels of plasma membrane. Hypoxia is accompanied by increased synthesis and secretion of proteins-regulators of oxidative stress, inflammation, apoptosis, and synaptic transmission. In this work, we investigated the effect of Sip1 mutations on the neuronal sensitivity of the brain to hypoxia and the formation of the hypoxic preconditioning phenomenon. The preconditioning effect was evaluated by the degree of suppressing activity of NMDA receptors by hypoxic episodes. Using fluorescent microscopy, we showed that cortical neurons from the brain of heterozygous (Sip1wt/fI) and homozygous (Sip1fI/fI) mice are characterized by the absence of the hypoxic preconditioning effect, whereas in Sip1wt/wt neurons the amplitudes of Ca2+ responses to the application of NMDA are suppressed after transient episodes of hypoxia. In addition, hypoxia exerted a significant toxic effect on Sip1fI/fI neurons, which was manifested not only by an increased sensitivity to a decrease of the oxygen partial pressure (pO2) and increased amplitudes of Ca2+ responses to application of NMDA after each hypoxic episode, but also by death of a considerable number of cells. 相似文献
A theoretical study of a sandwich compound with a metal monolayer sheet between two aromatic ligands is presented. A full
geometry optimization of the [Au3Cl3Tr2]2+ (1) compound, which is a triangular gold(I) monolayer sheet capped by chlorines and bounded to two cycloheptatrienyl (Tr)
ligands was carried out using perturbation theory at the MP2 computational level and DFT. Compound (1) is in agreement with
the 18–electron rule, the bonding nature in the complex may be interpreted from the donation interaction coming from the Tr
rings to the Au array, and from the back-donation from the latter to the former. NICS calculations show a strong aromatic
character in the gold monolayer sheet and Tr ligands; calculations done with HOMA, also report the same aromatic behavior
on the cycloheptatrienyl fragments giving us an insight on the stability of (1). The Au –Au bond lengths indicate that an
intramolecular aurophilic interaction among the Au(I) cations plays an important role in the bonding of the central metal
sheet.
Figure (a) Ground state geometry of complex 1; (b) Top view of compound 1 and Wiberg bond orders computed with the MP2/B1 computational method; (c) Lateral view of compound 1 and NICS values calculated with the MP2/B1 method; the values in parenthesis were obtained at the VWN/TZP level 相似文献
This study examined the effects of carbon dioxide (CO2)-, ozone (O3)-, and genotype-mediated changes in quaking aspen (Populus tremuloides) chemistry on performance of the forest tent caterpillar (Malacosoma disstria) and its dipteran parasitoid (Compsilura concinnata) at the Aspen Free-Air CO2 Enrichment (FACE) site. Parasitized and non-parasitized forest tent caterpillars were reared on two aspen genotypes under elevated levels of CO2 and O3, alone and in combination. Foliage was collected for determination of the chemical composition of leaves fed upon by forest tent caterpillars during the period of endoparasitoid larval development. Elevated CO2 decreased nitrogen levels but had no effect on concentrations of carbon-based compounds. In contrast, elevated O3 decreased nitrogen and phenolic glycoside levels, but increased concentrations of starch and condensed tannins. Foliar chemistry also differed between aspen genotypes. CO2, O3, genotype, and their interactions altered forest tent caterpillar performance, and differentially so between sexes. In general, enriched CO2 had little effect on forest tent caterpillar performance under ambient O3, but reduced performance (for insects on one aspen genotype) under elevated O3. Conversely, elevated O3 improved forest tent caterpillar performance under ambient, but not elevated, CO2. Parasitoid larval survivorship decreased under elevated O3, depending upon levels of CO2 and aspen genotype. Additionally, larval performance and masses of mature female parasitoids differed between aspen genotypes. These results suggest that host-parasitoid interactions in forest systems may be altered by atmospheric conditions anticipated for the future, and that the degree of change may be influenced by plant genotype. 相似文献
The effects of salinity (sea water at 0 ‰ versus 30 ‰) on gross rates of O2 evolution (JO2) and net rates of CO2 uptake (PN) were measured in the halotolerant estuarine C4 grasses Spartina patens, S. alterniflora, S. densiflora, and Distichlis spicata in controlled growth environments. Under high irradiance, salinity had no significant effect on the intercellular to ambient
CO2 concentration ratio (Ci/Ca). However, during photosynthesis under limiting irradiance, the maximum quantum efficiency of CO2 fixation decreased under salinity across species, suggesting there is increased leakage of the CO2 delivered to the bundle sheath cells by the C4 pump. Growth under salinity did not affect the maximum intrinsic efficiency of photosystem 2, PS2 (FV/FM) in these species, suggesting salinity had no effect on photosynthesis by inactivation of PS2 reaction centers. Under saline
conditions and high irradiance, PN was reduced by 75 % in Spartina patens and S. alterniflora, whereas salinity had no effect on PN in S. densiflora or D. spicata. This inhibition of PN in S. patens and S. alterniflora was not due to an effect on stomatal conductance since the ratio of Ci/Ca did not decrease under saline conditions. In growth with and without salt, PN was saturated at ∼500 μmol(quantum) m−2 s−1 while JO2 continued to increase up to full sunlight, indicating that carbon assimilation was not tightly coupled to photochemistry
in these halophytic species. This increase in alternative electron flow under high irradiance might be an inherent function
in these halophytes for dissipating excess energy. 相似文献
Natural bond orbital (NBO) analyses and dissected nucleus-independent chemical shifts (NICSπzz) were computed to evaluate the bonding (bond type, electron occupation, hybridization) and aromatic character of the three lowest-lying Si2CH2 (1-Si, 2-Si, 3-Si) and Ge2CH2 (1-Ge, 2-Ge, 3-Ge) isomers. While their carbon C3H2 analogs favor classical alkene, allene, and alkyne type bonding, these Si and Ge derivatives are more polarizable and can favor “highly electron delocalized”? and “non-classical”? structures. The lowest energy Si 2CH2 and Ge 2CH2 isomers, 1-Si and 1-Ge, exhibit two sets of 3–center 2–electron (3c-2e) bonding; a π-3c-2e bond involving the heavy atoms (C–Si–Si and C–Ge–Ge), and a σ-3c-2e bond (Si–H–Si, Ge–H–Ge). Both 3-Si and 3-Ge exhibit π and σ-3c-2e bonding involving a planar tetracoordinated carbon (ptC) center. Despite their highly electron delocalized nature, all of the Si2CH2 and Ge2CH2 isomers considered display only modest two π electron aromatic character (NICS(0)πzz=--6.2 to –8.9 ppm, computed at the heavy atom ring center) compared to the cyclic-C 3H2 (–13.3 ppm).
The spatial variation of soil greenhouse gas fluxes (GHG; carbon dioxide—CO2, methane—CH4 and nitrous oxide—N2O) remains poorly understood in highly complex ecosystems such as tropical forests. We used 240 individual flux measurements of these three GHGs from different soil types, at three topographical positions and in two extreme hydric conditions in the tropical forests of the Guiana Shield (French Guiana, South America) to (1) test the effect of topographical positions on GHG fluxes and (2) identify the soil characteristics driving flux variation in these nutrient-poor tropical soils. Surprisingly, none of the three GHG flux rates differed with topographical position. CO2 effluxes covaried with soil pH, soil water content (SWC), available nitrogen and total phosphorus. The CH4 fluxes were best explained by variation in SWC, with soils acting as a sink under drier conditions and as a source under wetter conditions. Unexpectedly, our study areas were generally sinks for N2O and N2O fluxes were partly explained by total phosphorus and available nitrogen concentrations. This first study describing the spatial variation of soil fluxes of the three main GHGs measured simultaneously in forests of the Guiana Shield lays the foundation for specific studies of the processes underlying the observed patterns. 相似文献
The sensitivity of phytoplankton species for hydrogen peroxide (H2O2) was analyzed by pulse amplitude modulated (PAM) fluorometry. The inhibition of photosynthesis was more severe in five tested
cyanobacterial species than in three green algal species and one diatom species. Hence the inhibitory effect of H2O2 is especially pronounced for cyanobacteria. A specific damage of the photosynthetic apparatus was demonstrated by changes
in 77 K fluorescence emission spectra. Different handling of oxidative stress and different cell structure are responsible
for the different susceptibility to H2O2 between cyanobacteria and other phytoplankton species. This principle may be potentially employed in the development of new
agents to combat cyanobacterial bloom formation in water reservoirs. 相似文献