534 research outputs found
Species-specific and needle age-related responses of photosynthesis in two Pinus species to long-term exposure to elevated CO2 concentration
There is, so far, no common conclusion about photosynthetic responses of trees to long-term exposure to elevated CO2. Photosynthesis and specific leaf area (SLA) of 1-year-old and current-year needles in Pinus koraiensis and P. sylvestriformis grown in open-top chambers were measured monthly for consecutive two growing seasons (2006, 2007) after 8-9years of CO2 enrichment in northeastern China, to better understand species-specific and needle age-related responses to elevated CO2 (500μmolmol−1CO2). The light-saturated photosynthetic rates (P Nsat) increased in both species at elevated CO2, but the stimulation magnitude varied with species and needle age. Photosynthetic acclimation to elevated CO2, in terms of reduced V cmax (maximum carboxylation rate) and J max (maximum electron transport rate), was found in P. koraiensis but not in P. sylvestriformis. The photosynthetic parameters (V cmax, J max, P Nsat) measured in different-aged needles within each species responded to elevated CO2 similarly, but elevated CO2 resulted in much pronounced variations of those parameters in current-year needles than in 1-year-old needles within each species. This result indicated that needle age affects the magnitude but not the patterns of photosynthetic responses to long-term CO2 enrichment. The present study indicated that different species associated with different physioecological properties responded to elevated CO2 differently. As global change and CO2 enrichment is more or less a gradual rather than an abrupt process, long-term global change experiments with different plant species are still needed to character and better predict the global change effects on terrestrial ecosystem
Simultaneous quantitative assessment of circulating cell-free mitochondrial and nuclear DNA by multiplex real-time PCR
Quantification of circulating nucleic acids in plasma and serum could be used as a non-invasive diagnostic tool for monitoring a wide variety of diseases and conditions. We describe here a rapid, simple and accurate multiplex real-time PCR method for direct synchronized analysis of circulating cell-free (ccf) mitochondrial (mtDNA) and nuclear (nDNA) DNA in plasma and serum samples. The method is based on one-step multiplex real-time PCR using a FAM-labeled MGB probe and primers to amplify the mtDNA sequence of the ATP 8 gene, and a VIC-labeled MGB probe and primers to amplify the nDNA sequence of the glycerinaldehyde-3-phosphate-dehydrogenase (GAPDH) gene, in plasma and serum samples simultaneously. The efficiencies of the multiplex assays were measured in serial dilutions. Based on the simulation of the PCR reaction kinetics, the relative quantities of ccf mtDNA were calculated using a very simple equation. Using our optimised real-time PCR conditions, close to 100% efficiency was obtained from the two assays. The two assays performed in the dilution series showed very good and reproducible correlation to each other. This optimised multiplex real-time PCR protocol can be widely used for synchronized quantification of mtDNA and nDNA in different samples, with a very high rate of efficiency
Asthma Pregnancy Alters Postnatal Development of Chromaffin Cells in the Rat Adrenal Medulla
Background: Adrenal neuroendocrine plays an important role in asthma. The activity of the sympathoadrenal system could be altered by early life events. The effects of maternal asthma during pregnancy on the adrenal medulla of offspring remain unknown. Methodology/Principal Findings: This study aims to explore the influence of maternal asthma during pregnancy on the development and function of adrenal medulla in offspring from postnatal day 3 (P3) to postnatal day 60 (P60). Asthmatic pregnant rats (AP), nerve growth factor (NGF)-treated pregnant rats (NP) and NGF antibody-treated pregnant rats (ANP) were sensitized and challenged with ovalbumin (OVA); NP and ANP were treated with NGF and NGF antibody respectively. Offspring rats from the maternal group were divided into four groups: offspring from control pregnant rats (OCP), offspring from AP (OAP), offspring from NP (ONP), and offspring from ANP (OANP). The expressions of phenylethanolamine N-methyltransferase (PNMT) protein in adrenal medulla were analyzed. The concentrations of epinephrine (EPI), corticosterone and NGF in serum were measured. Adrenal medulla chromaffin cells (AMCC) were prone to differentiate into sympathetic nerve cells in OAP and ONP. Both EPI and PNMT were decreased in OAP from P3 to P14, and then reached normal level gradually from P30 to P60, which were lower from birth to adulthood in ONP. Corticosterone concentration increased significantly in OAP and ONP. Conclusion/Significance: Asthma pregnancy may promote AMCC to differentiate into sympathetic neurons in offspring rats and inhibit the synthesis of EPI, resulting in dysfunction of bronchial relaxation
Soil Respiration in Relation to Photosynthesis of Quercus mongolica Trees at Elevated CO2
Knowledge of soil respiration and photosynthesis under elevated CO2 is crucial for exactly understanding and predicting the carbon balance in forest ecosystems in a rapid CO2-enriched world. Quercus mongolica Fischer ex Ledebour seedlings were planted in open-top chambers exposed to elevated CO2 (EC = 500 µmol mol−1) and ambient CO2 (AC = 370 µmol mol−1) from 2005 to 2008. Daily, seasonal and inter-annual variations in soil respiration and photosynthetic assimilation were measured during 2007 and 2008 growing seasons. EC significantly stimulated the daytime soil respiration by 24.5% (322.4 at EC vs. 259.0 mg CO2 m−2 hr−1 at AC) in 2007 and 21.0% (281.2 at EC vs. 232.6 mg CO2 m−2 hr−1 at AC) in 2008, and increased the daytime CO2 assimilation by 28.8% (624.1 at EC vs. 484.6 mg CO2 m−2 hr−1 at AC) across the two growing seasons. The temporal variation in soil respiration was positively correlated with the aboveground photosynthesis, soil temperature, and soil water content at both EC and AC. EC did not affect the temperature sensitivity of soil respiration. The increased daytime soil respiration at EC resulted mainly from the increased aboveground photosynthesis. The present study indicates that increases in CO2 fixation of plants in a CO2-rich world will rapidly return to the atmosphere by increased soil respiration
Observation of in
Using a sample of events recorded with
the BESIII detector at the symmetric electron positron collider BEPCII, we
report the observation of the decay of the charmonium state
into a pair of mesons in the process
. The branching fraction is measured for the first
time to be , where the first uncertainty is
statistical, the second systematic and the third is from the uncertainty of
. The mass and width of the are
determined as MeV/ and
MeV.Comment: 13 pages, 6 figure
Measurement of azimuthal asymmetries in inclusive charged dipion production in annihilations at = 3.65 GeV
We present a measurement of the azimuthal asymmetries of two charged pions in
the inclusive process based on a data set of 62
at the center-of-mass energy GeV collected with
the BESIII detector. These asymmetries can be attributed to the Collins
fragmentation function. We observe a nonzero asymmetry, which increases with
increasing pion momentum. As our energy scale is close to that of the existing
semi-inclusive deep inelastic scattering experimental data, the measured
asymmetries are important inputs for the global analysis of extracting the
quark transversity distribution inside the nucleon and are valuable to explore
the energy evolution of the spin-dependent fragmentation function.Comment: 7 pages, 5 figure
Measurement of the Cross Section between 600 and 900 MeV Using Initial State Radiation
We extract the cross section in the energy
range between 600 and 900 MeV, exploiting the method of initial state
radiation. A data set with an integrated luminosity of 2.93 fb taken at
a center-of-mass energy of 3.773 GeV with the BESIII detector at the BEPCII
collider is used. The cross section is measured with a systematic uncertainty
of 0.9%. We extract the pion form factor as well as the
contribution of the measured cross section to the leading order hadronic vacuum
polarization contribution to . We find this value to be
.Comment: 14 pages, 7 figures, accepted by PL
Study of
We present an analysis of the decay based
on data collected by the BESIII experiment at the resonance. Using
a nearly background-free sample of 18262 events, we measure the branching
fraction . For GeV/ the partial branching fraction is
. A partial wave analysis shows that the dominant
component is accompanied by an \emph{S}-wave contribution accounting for
of the total rate and that other components are
negligible. The parameters of the resonance and of the
form factors based on the spectroscopic pole dominance predictions are also
measured. We also present a measurement of the helicity
basis form factors in a model-independent way.Comment: 17 pages, 6 figure
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