Institutional Repository of Chengdu Institute of Biology, CAS
Not a member yet
6513 research outputs found
Sort by
多酶级联反应催化的环氧醇立体互补性差向异构化
No full text动态动力学拆分是制备光学纯手性中间体的重要手段之一。本研究以光学纯的多手性中心的缩水甘油醇为目标产物,将苯乙烯单加氧酶(SMO)与两个醇脱氢酶/羰基还原酶(ADH)共表达于大肠杆菌BL21中,构建了整细胞催化的多酶级联反应体系。其中苯乙烯单加氧酶负责选择性地向底物中引入手性环氧基团,而一对羰基还原酶进一步完成对羟基的差向异构化(Fig.1)。该多酶级联反应体系高效运转的重点是还原型辅酶对反应体系的调控作用。还原型辅酶I(NADH)参与的环氧化作用(Step1)与氧化型辅酶I(NAD~+)参与的脱氢反应(Step2),不仅实现了辅酶I的自循环,控制了反应顺序,还将还原型辅酶II(NADPH)参与的还原反应(Step3)与前两步反应"隔离"开,实现了对仲醇的动态动力学拆分。三步串联反应有序进行,互不干扰,使目标产物的理论产率可以达到100%。以三个酶共表达的休止细胞为催化剂,检测了该级联反应体系对12种底物的转化情况,1-2小时内产率36%至>99%,大多数情况下具备优异的对映体及非对映体选择性。运用两对选择性和辅酶适应性互补的羰基还原酶分别与苯乙烯单加氧酶组合得到两个立体互补性的催化系统,可以分别获得S-和R-手性醇,最终实现了环氧醇立体互补性差向异构化,为多手性基团有机砌块的合成提供了新思路
Analysis of oxovanadium(IV) complexes using electrospray mass spectrometry: Molecular ion formed by loss of an electron, and its product ions trapping oxygen
No full textRationale: In addition to their biological properties, oxovanadium complexes have been widely applied as catalysts because of their excellent catalytic-oxidation capability. Recently, monometallic oxovanadium(IV) complexes have been used as catalysts in the electrophilic trifluoromethylation of silyl ketene imines. The study of catalysts can contribute to an understanding of the reaction mechanism. Methods: Six monometallic oxovanadium(IV) complexes were analyzed by electrospray ionization time-of flight mass spectrometry (ESI-TOFMS), and collision-induced dissociation mass spectrometry (CID-MS) experiments were conducted for selected cations [M](+) of oxovanadium(IV) complexes as well as a deuterium-labeled complex. Different collision gases were used to understand the source of the O-2 and H2O engaged in the gas-phase ion-molecule reaction. Results: The oxovanadium(IV) complexes formed [M](+) ions by loss of an electron, with [M + 14](+) ions being formed from [M](+) by loss of H2O and addition of O-2. The fragmentation pathways of the [M](+) cations were further studied by ESI-MS/MS, and several ions produced by gas-phase ion-molecule reactions were detected and characterized, including vanadium-oxo, -peroxo and derivatives. Conclusions: Several unexpected ions were detected, including [M](+), [M + 14](+) and ions produced from gas-phase ion-molecule reactions. The study has contributed to the understanding of the structure and character of oxovanadium(IV) complexes, and it could facilitate the design of new oxovanadium catalysts and an understanding of their reaction mechanism
Unexpected hydrated ions in the detection of sodium adduct coumarins using electrospray tandem mass spectrometry
No full textA series of coumarins were analyzed using electrospray ionization quadrupole time-of-flight tandem mass spectrometry in the positive-ion mode. Unexpected hydrated ions ([M + H2O + Na] (+)) was observed upon collision- induced dissociation of the sodiated ions ([M + Na] (+)) of eight coumarins. Several factors which affected relative abundance of [M + H2O + Na] (+) ions such as collision energy, concentration and solvent were investigated. None of them have effect on the relative abundance of [M + H2O + Na] (+). However, the peak of hydrated ions was not detected in the further collision- induced dissociation of protonated ions of coumarins. Apigenin and Quercetin sharing similar benzopyrone structural unit with coumarins are selected for tandem mass spectrometry analysis. There were no hydrated ions in their tandem mass spectrometry spectra of the precursor [M + Na] (+) ions. Thus, both coumarins and sodium were necessary for the formation of [M + H2O + Na] (+). Together with the result that hydrated ions are not formed by hydrolysis reactions, a six- membered ring structure which involves with the formation of [M + H2O + Na] (+) was presented. And D- labeling experiment indicates that the H2O molecule did not come from solvent
Cloning cDNA and functional characterization of UDP-glucose pyrophosphorylase in Dendrobium officinale
No full textDendrobium officinale is a traditional Chinese medicinal herb that produces promising bioactive polysaccharides. However, the biosynthetic pathway of polysaccharides in this herb remains to be elucidated. The uridine diphosphate glucose pyrophosphorylase (UGPase) is a key enzyme for the production of uridine diphosphate glucose, which is a major glycosyl donor for synthesis of polysaccharides. This study identified a novel UGPase gene from D. officinale termed as DoUGP. Bioinformatics and subcellular-localization of the DoUGP protein indicate that it belongs to the UGPase-A type and was localized in cytoplasm. The DoUGP was revealed to be constitutively expressed in all organs, and the highest mRNA content was detected in stems, the organs with the highest polysaccharide content. Furthermore, sucrose feeding experiments in D. officinale demonstrate that sucrose addition could increase DoUGP transcription significantly and enhance polysaccharide accumulation accordingly. Together, we conclude that DoUGP probably plays an important role in polysaccharide biosynthesis of D. officinale and is a potential target for quality breeding of this orchid
高产小麦品种川麦42产量性状QTL分析
No full text解析骨干亲本产量性状分子模块对小麦品种分子设计与分子育种具有重要作用.以突破性高产小麦品种川麦42和川农16及其构建的127个重组自交系(RIL)群体(F10)为实验材料,分别于2014年和2015年在四川双流、什邡3个环境下种植,并测量千粒重、穗粒数等产量性状.利用Illumina公司的小麦90K SNP芯片对亲本和群体进行全基因组81 587个单核苷酸多态性分型.使用QTL Ici Mapping软件绘制遗传连锁图,并定位到一些控制产量性状的数量性状位点(QTL).结果显示:遗传图谱含8 580个SNP标记,全长3 147.1 c M,平均密度0.37 c M/标记.共定位到21个效应来自川麦42的产量性状QTL(解释表型变异>10%),分别位于1B、1D、2B、2D、3B、3D、4A、5A、5B、6B和7B,控制着株高、穗长、穗重、千粒重等性状,解释表型变异10.01%-23.07%.其中,1D、2B、5A、5B存在控制株高、籽粒面积、千粒重、穗长、穗重,并且在多个环境下均出现的QTL.此外,2B、5A、5B、7B上存在同时控制多个性状的QTL.这些研究结果可为深入了解骨干亲本川麦42产量性状遗传特性提供重要信息
Picea asperata pioneer and fibrous roots have different physiological mechanisms in response to soil freeze-thaw in spring
No full textAbout 70 % of the total land area in the world are affected by soil freeze and thaw (FT) cycles. Root is the first organ of plant to sense soil environment and it is unclear how it copes with the soil FT. Based on the different functions of firstorder pioneer and fibrous roots in woody plants, we hypothesize that pioneer and fibrous roots respond differently. The experiment was conducted in a growth chamber using Picea asperata seedlings. We designed the FT based on field observation data. The physiological responses in fibrous and pioneer roots were examined. Fibrous roots had higher root vitality and N content, whereas pioneer roots exhibited higher total nonstructural saccharide content. The accumulation of O-2(-) under FT treatment was similar in the two types of roots. Pioneer roots showed higher osmolyte (especially proline) content, whereas fibrous roots had higher peroxidase activity. The present study confirmed that fibrous roots have stronger metabolism ability, whereas pioneer roots are the key storage organs. FT in the temperature range from -5 to 5 degrees C are mild and do not cause serious injury to roots. Pioneer roots have higher tolerance to soil FT in spring than fibrous roots. The roots have different strategies to FT: fibrous roots increase the antioxidant system, whereas pioneer roots accumulate more osmolytes. Such knowledge can help us to understand how roots of woody plants cope with soil FT
Comparisons of photosynthesis-related traits of 27 abundant or subordinate bryophyte species in a subalpine old-growth fir forest
No full textBryophyte communities can exhibit similar structural and taxonomic diversity as vascular plant communities, just at a smaller scale. Whether the physiological diversity can be similarly diverse, and whether it can explain local abundance patterns is unknown, due to a lack of community-wide studies of physiological traits. This study re-analyzed data on photosynthesis-related traits (including the nitrogen, phosphorus and chlorophyll concentrations, photosynthetic capacities, and photosynthetic nutrient use efficiencies) of 27 bryophyte species in a subalpine old-growth fir forest on the eastern Tibetan Plateau. We explored differences between taxonomic groups and hypothesized that the most abundant bryophyte species had physiological advantages relative to other subdominant species. Principal component analysis (PCA) was used to summarize the differences among species and trait values of the most abundant and other co-occurring subdominant species. Species from the Polytrichaceae were separated out on both PCA axes, indicating their high chlorophyll concentrations and photosynthetic capacities (axis 1) and relatively high-light requirements (axis 2). Mniaceae species also had relatively high photosynthetic capacities, but their light saturation points were low. In contrast, Racomitrium joseph-hookeri and Lepidozia reptans, two species with a high shoot mass per area, had high-light requirements and low nutrient and chlorophyll concentrations and photosynthetic capacities. The nutrient concentrations, photosynthetic capacities, and photosynthetic nutrient use efficiencies of the most abundant bryophyte species did not differ from co-occurring subdominant species. Our research confirms the links between the photosynthesis-related traits and adaptation strategies of bryophytes. However, species relative abundance was not related to these traits
Genetic diversity and population structure of Indigofera szechuensis complex (Fabaceae) based on EST-SSR markers
No full textIndigofera, the third largest genus of Fabaceae, comprises approximately 750 species worldwide with a pantropical distribution. Eight Indigofera species, namely I. calcicola, I delavayi, I. franchetii, I hancockii, I. lenticellata, I. pendula, I. rigioclada, and I. szechuensis, are considered a species complex because of their morphological similarities and the phylogenetic analysis based on Internal Transcribed Spacer (ITS). Small populations of these species are allopatrically distributed in Hengduan Mountains in China. Although considerable EST-SSR markers have been developed from the transcriptome of I. szechuensis, no codominant markers have been applied to study population genetic structure of the complex. In this study, we selected 66 EST-SSR markers which were transferable in Indigofera szechuensis complex for estimating polymorphism, of which 44 EST-SSRs (66.67%) were polymorphic. Amplification with selected 23 polymorphic EST-SSRs revealed a moderately high genetic diversity in this complex. The mean value of Observed number of alleles, Expected heterozygosity, Polymorphism information content and Shannon's information index was 10.4783, 0.4335, 0.6228 and 1.4369 respectively. A total of 758 genotypes were detected, with an average of 32.9565 genotypes per locus. The Mantel test showed a significant correlation between genetic and geographic distance (r = 0.0748, P = 0.0100). High differentiation and limited gene flow were detected among all populations (F-st = 0.3589, Nm = 0.5168). The PCoA and structure analysis grouped 31 populations of Indigofera szechuensis complex into five main species. I. delavayi was obviously separated from other species, and the result was in accordance with that of morphology and phylogeny. I. pendula was a separate species, and had two distinct phenotypes. Four L szechuensis populations (Pop23, Pop24, Pop27 and Pop30) were the same species. I. calcicola, I hancockii, I. rigioclada, I. franchetii, I. lenticellata, and L szechuensis, distributed in southwest of Jinshajiang, could be considered as the same species; the species of I. franchetii, I. lenticellata, and I. szechuensis distributed in northeast of Jinshajiang could be considered as another separate species. Given the above information, the morphological classification of I. calcicola, I franchetii, I. hancockii, I. lenticellata, I. rigioclada, and I. szechuensis was incredible
The effect of simulated warming on root dynamics and soil microbial community in an alpine meadow of the Qinghai-Tibet Plateau
No full textPrevious studies have explored the effects of global change on above-ground vegetation in grassland ecosystems. Few, however, have investigated the responses of root dynamics and soil microbes to simulated warming in alpine meadows of the Qinghai-Tibet Plateau. This research used field open top chamber experiment to examine warming's impacts. Root production, mortality, and turnover were observed in situ using minirhizotron tubes, while soil microbial community composition and diversity were assessed by using phospholipid-derived fatty acids (PLFA) and Biolog-Eco plates. The results showed that 1) warming shifted the root standing crop distribution to deeper soil while increasing the accumulated root mortality and root production at 0-10 cm soil depth; 2) warming increased the abundance of fungal PLFAs while decreasing the abundance of other functional groups; 3) warming decreased the soil microbial functional diversity at the different soil layers; 4) bacterial and fungal PLFA contents were positively correlated with root mortality and turnover but were negatively correlated with root standing crop; 5) root dynamics significantly affect carbon utilization of the soil microbial community; and warming induced changes in root dynamics are associated with soil microbial community structure and function. Overall, these findings indicate that warming alters root production, mortality, and turnover and the relative abundance of different microorganisms in different soil layers. As a result, warming tended to shift microbial communities from bacteria toward fungi, leading to changes in the microbial community structure in different soil layers. (C) 2017 Elsevier B.V. All rights reserved
Effect of nitrogen and phosphorus application on agricultural soil food webs
No full textAim of the present research is to investigate the effect of nitrogen (N) and phosphorus (P) on soil food webs (microbes, nematodes and microarthropods) trophic interactions in agriculture ecosystems. A complete randomized block design experiment of N and P fertilization was initiated in 2010 with four treatments: (1) P-addition, (2) N-addition, (3) NP-addition and (4) control. After 4years of fertilization, compared with control, N-addition had a negative effect on microarthropods and clarify indirectly by significantly (P<0.05) increasing soil total nitrogen (0.37g kg(-1)) and available nitrogen (20.03mg kg(-1)). The reduction in microarthropods resulted significant (P<0.05) increase in bacterivores and fungivores feeding on bacteria and fungi, an example of top-down control. P-addition had indirect negative effects on microarthropods by means of significantly (P<0.05) increasing soil total phosphorus (0.62g kg(-1)) and available phosphorus (24.17mg kg(-1)), aggravated fungivores feeding on fungi and strengthened top-down control. NP-addition significantly (P<0.05) increased total microbial biomass, nematodes and microarthropods and resulted in bottom-up control. These results suggested that top-down effects were the dominant force in N- or P-addition treatments. NP-addition strengthened bottom-up control by enriching food resource. Unbalance fertilization could pose adverse on agricultural soil ecosystem and yield potential of crops