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Polyketide synthases (PKSs) utilize the products of primary metabolism to synthesize a wide array of secondary metabolites in both prokaryotic and eukaryotic organisms. PKSs can be grouped into three distinct classes, type I, II, and III, based on enzyme structure, substrate specificity, and catalytic mechanisms. The type III PKS enzymes function as homodimers, and are the only class of PKS that do not require acyl carrier protein. Plant type III PKS enzymes, also known as chalcone synthase (CHS)-like enzymes, are of particular interest due to their functional diversity. In this study, we mined type III PKS gene sequences from the genomes of six aquatic algae and twenty-five land plants (one bryophyte, one lycophyte, two basal angiosperms, sixteen core eudicots, and five monocots). PKS III sequences were found relatively conserved in all embryophytes, but not exist in algae. We also examined gene expression patterns by analyzing available transcriptome data, and identified potential cis regulatory elements in upstream sequences. Phylogenetic trees of dicots angiosperms showed that plant type III PKS proteins fall into three clades. Clade A contains CHS/STS-type enzymes coding genes with diverse transcriptional expression patterns and enzymatic functions, while clade B is further divided into subclades b1 and b2, which consist of anther-specific CHS-like enzymes. Differentiation regions, such as amino acids 196-207 between clades A and B, and predicted positive selected sites within α-helixes in late appeared branches of clade A, account for the major diversification in substrate choice and catalytic reaction. The integrity and location of conserved cis-elements containing MYB and bHLH binding sites can affect transcription levels. Potential binding sites for transcription factors such as WRKY, SPL or AP2/EREBP may contribute to tissue- or taxon-specific differences in gene expression. Our data shows that gene duplications and functional diversification of plant type III PKS enzymes played a critical role in the ancient conquest of the land by early plants and angiosperm diversification. Keywords PKS III multigene family, CHS, STS, phylogenetic reconstruction, functional diversification, gene expression, cis-elements
Objective: To investigate the effect of Double-reinforcing and One-unblocking techniques of needling on biochemical indicators of bone metabolism in rat model of postmenopausal osteoporosis.Methods: 50 SD rats were divided into five groups randomly,which were control group,model group,normal group,treatment group and Chinese patent medicine group of 10 rats each group.In model group,normal group,treatment group and Chinese patent medicine group the rats were made into the model of experimental postmenopausal osteoporosis by ovariectomy.Then Ca,P and ALP in serum,Ca,P and Cr in urine,BGP in blood and DPD in urine were determined.Results: In model group Ca decreased and P increased markedly,and BGP increased remarkably too(P0.01).ALP increased but not markedly.Compared with in model group,Ca increased,P decreased and BGP increased all remarkably in treatment group and Chinese patent medicine group(P0.01),but treatment group did better than normal group(P0.01).ALP decreased but not markedly.In model group Ca/Cr and P/Cr increased markedly(P0.01).Compared with model group Ca/Cr and P/Cr in each group decreased(P0.01).In model group DPD increased significantly(P0.01).But compare with model group DPD in urine in treatment group decreased significantly(P0.01).Conclusion: BGP was increased significantly after treatment with Double-reinforcing and One-unblocking techniques of needling,which shows that osteoblast activity is strengthened and bone formation increases.Ca increases,P decreases,Ca/Cr,P/Cr and DPD decrease which suggest that Double-reinforcing and One-unblocking techniques of needling can promote gastrointestinal absorptive function,encourage Ca,P and other nutrient substance to be absorbed and utilized,regulate the metabolism of Ca and P,cut down DPD concentration which is urinary type I collagen decomposition products,and increase BGP concentration so as to inhibit bone resorption and promote bone formation.This means that traditional Chinese medicine treatment can regulate the metabolism of Ca and P,promote bone formation,and slow down the bone absorption.
Interfacial tension (IFT) between CO2 and formation water is one of the most important parameters for CO2 capture and storage, for it controls the transport properties of both phases in the formation. In order to rapidly and accurately predict the IFT of the CO2-brine system, 1 677 sets of measured IFT data from previous studies were acquired. A wavelet neural network (WNN) prediction model was proposed in view of 6 parameters including the pressure, the temperature, the CH4 molality and the N2 molality in CO2 gas, the monovalent cation (Na+ and K+) concentration and the bivalent cation (Ca2+ and Mg2+) concentration. The simulation results show that a 3-layer (6-16-1) WNN model comes out of 839 data as the training datasets. The mean absolute error (MMAE), the mean relative error (MMARE), the root mean squared error(MMSE) and the determination coefficient (R2) of the WNN model were 1.23 mN/m, 3.30%, 2.30 mN2/m2 and 0.988, respectively. The performance of the WNN model was further compared with one newly proposed multivariate fitting model and the BP neural network model. The comparison results suggest that the WNN model is better than the other 2.
Taking a rice-wheat rotation system in the suburb of Nanjing, Jiangsu Province of East China as test object, this paper studied the fluxes of CH4 and N2O and their annual dynamics under different farming managements in 2010-2011, and the field observation data were applied to validate the process-based model, denitrification-decomposition (DNDC) model, aimed to approach the applicability of the model to this rotation system, and to use this model to simulate the effects of different environmental factors and farming managements on the global warming potentials (GWPs) of CH4 and N2O. The results showed that except in the treatment control and during wheat growth season, the simulated cumulative emissions of CH4 and N2O from the rotation system in all treatments were basically in coincide with the observed data, the relative deviations being from 7. 1% to 26.3%, and thus, the DNDC model could be applied to simulate the GWPs of cumulative emissions of CH4 and N2O as affected by various environmental factors or management practices. The sensitivity test showed that the GWPs of CH4 and N2O varied significantly with the changes of environmental factors such as the mean annual air temperature, soil bulk density, soil organic carbon, soil texture, and soil pH. Farming managements such as N fertilization, straw returning, and duration of mid-season drainage also had significant effects on the GWPs of CH4 and NO20. Therefore, the above-mentioned environmental factors and farming managements should be taken into account to estimate the greenhouse gases emission from the rice-wheat cropping system on site-specific or regional scale.
Ecological speciation is a common mechanism by which new species arise. Despite great efforts, the role of gene expression in ecological divergence and speciation is poorly understood. Here, we conducted a genome-wide gene expression investigation of two Oryza species that are evolutionarily young and distinct in ecology and morphology. Using digital gene expression technology and the paired-end RNA sequencing method, we obtained 21,415 expressed genes across three reproduction-related tissues. Of them, approximately 8% (1,717) differed significantly in expression levels between the two species and these differentially expressed genes are randomly distributed across the genome. Moreover, 62% (1,064) of the differentially expressed genes exhibited a signature of directional selection in at least one species. Importantly, the genes with differential expression between species evolved more rapidly at the 5′ flanking sequences than the genes without differential expression relative to coding sequences, suggesting that cis-regulatory changes are likely adaptive and play an important role in the ecological divergence of the two species. Finally, we showed evidence of significant differentiation between species in phenotype traits and observed that genes with differential expression were overrepresented with functional terms involving phenotypic and ecological differentiation between the two species, including reproduction- and stress-related characteristics. Our findings demonstrate that ecological speciation is associated with widespread and adaptive alterations in genome-wide gene expression and provide new insights into the importance of regulatory evolution in ecological speciation in plants.
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