This study aimed to investigate drought resistance of the LY1306 tobacco strain. Seedlings of tobacco strains LY1306, ZhongYan 100 (ZY100) and Hong Hua Da Jin Yuan (HHDJY) were treated with ...polyethylene glycol (PEG)-6000 to induce osmotic stress. As validation, water-deficit-induced drought treatments, including mild drought (MD; watering 1.5 L/week) and severe drought (SD, without watering) were carried out. Changes in cell morphology, leaf water potential, antioxidant enzyme activity, as well as contents of malondialdehyde (MDA) and proline were determined for each treatment. Transcriptome sequencing was performed for the seedlings treated with 15% PEG-6000. No obvious changes were observed in morphology of LY1306 and ZY100 under osmotic or drought stress; whereas, visible wilting was observed in HHDJY. Superoxide dismutase and peroxidase activities of LY1036 and ZY100 under osmotic stress were significantly higher than those of HHDJY. Under SD, the MDA content of LY1306 was significantly lower and the proline content of LY1306 was significantly higher than that of HHDJY. Differential genes between LY1306, ZY100 and HHDJY were enriched in functions about alpha-linolenic acid, and arginine and proline metabolisms. LY1306 could increase its antioxidant enzyme activities and proline accumulation in response to drought stress, probably by regulating drought resistance-related pathways and genes.
The weak basic site is the primary puller of the reaction process, while medium basic sites guarantee fundamental catalytic activity. The weak and medium basic sites synergistically catalyze the ...hydrogenation of CO2 to formic acid.
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•A Ni/MgaAlOx catalyst was prepared using Ni-Mg-Al hydrotalcite as a precursor.•The properties of basic sites can be modulated by varying the Mg/Al ratio.•The Ni/Mg0.2AlOx catalyst could achieve a formate reaction yield of 41.0 % and a rate of 518.4 mg⋅gcat−1⋅h−1.•The weak basic site was the primary puller of the reaction; the medium basic site was the crucial assurance of activity.
Basic sites profoundly affect the mode and strength of CO2 adsorption in the hydrogenation of CO2 to formic acid (FA), however, the mechanism by which the quantities and strength of basic sites affect the reaction process is not yet clear. Herein, a Ni/MgaAlOx catalyst has been developed and the basic sites of the catalyst can be modulated by simply altering the Mg/Al ratio. Through a series of characterizations and experiments, it was observed that weak and medium basic sites synergistically catalyzed the hydrogenation of CO2 to formic acid, and a reasonable number of weak basic sites can improve reaction performance when a sufficient number of medium basic sites guarantee the fundamental catalytic activity. Moreover, the number and distribution of basic sites are also tightly related to metal-support interactions. This strategy provides theoretical guidance and a feasible scheme for optimizing the performance of non-precious metal heterogeneous catalysts.
•Tyrosinase derived from Bacillus megaterium catalyzed TFDG synthesis.•A directed evolution strategy was used for enzyme screening.•There were changes in the surface potential and hydrogen bonds of ...the protein.•These changes increased the activity of EGCG and ECG.•Bmtyrc-3 possesses potential industrial application value.
Theaflavin-3,3ʹ-digallate (TFDG) in black tea possesses several health benefits. However, low TFDG yields limit its application. Herein, tyrosinases from Bacillus megaterium (Bmtyrc) were used to synthesize TFDG. To improve the catalytic efficiency of tyrosinase, a directed evolution strategy and a high-throughput screening method was employed. Compared with the wild type, mutant Bmtyrc-3 (N205D/D166E/D167G/F197W) showed 6.46 and 4.91-folds higher specific activity and 51.97- and 1.95-folds higher Vmax values towards epigallocatechin gallate (EGCG) and epicatechin gallate (ECG), respectively. Moreover, Bmtyrc-3 displayed significantly enhanced catalytic efficiencies, and the space–time yield of TFDG was 35.35 g L-1d-1. Bmtyrc-3 presents a broader substrate binding area, caused by a mutation (N205D) encompassing the active site. Changes in the potential of the substrate binding site and hydrogen bonds, and the electrostatic effect on the protein surface resulted in an increased activity of the substrates EGCG and ECG.
LncRNAs play a part in numerous momentous processes of biology such as disease diagnoses, preventions and treatments. The associations between various diseases and lncRNAs are one of the crucial ...approaches to learn the role and status of lncRNAs in human diseases. With the researches on lncRNA and diseases, multiple methods based on neural network have been employed to predict these associations. However, the deep and complicated characteristic representations of lncRNA-disease associations were failed to be extracted, and the discriminative contributions of the interactions, correlations, and similarities among miRNAs diseases, and lncRNAs for the correlation predictions were ignored. In this paper, based on the multibiology premise of lncRNAs, miRNAs, and diseases, a dual attention network was proposed to predict the model of lncRNA-disease associations for miRNAs, the disease characteristic matrix, and lncRNAs. Through two attention modules, we enable the model to learn the nonlinear, more complex and useful features of lncRNA, miRNA, and disease characteristic matrix. For the feature embedding matrix composed of lncRNA-disease, the connection between lncRNA-disease feature embedding matrix and lncRNA, miRNA, and disease characteristic matrix was enhanced through deconvolution and feature fusion layer. Compared with several latest methods, the method proposed in this paper can produce better performance. Researches on the cases of osteosarcoma, lung cancer, and gastric cancer have confirmed the effective recognition of potential lncRNA-disease associations.
Mitochondria manganese superoxide dismutase (SOD2) is an important antioxidant enzyme, deficiency of which is associated with various human diseases. The known primary regulation of SOD2 is through ...transcriptional activation. Here, we report that SOD2 is acetylated at Lys 68 and that this acetylation decreases SOD2 activity. Mitochondrial deacetylase SIRT3 binds to, deacetylates and activates SOD2. Increase of reactive oxygen species (ROS) levels stimulates SIRT3 transcription, leading to SOD2 deacetylation and activation. SOD2‐mediated ROS reduction is synergistically increased by SIRT3 co‐expression, but is cancelled by SIRT3 depletion. These results reveal a new post‐translational regulation of SOD2 by means of acetylation and SIRT3‐dependent deacetylation in response to oxidative stress.
Mitochondria manganese superoxide dismutase (SOD2) is a major antioxidant enzyme associated with several diseases. This study shows that SOD2 is inhibited by acetylation and activated by SIRT3‐mediated deacetylation in response to reactive oxygen species (ROS).
Protein acetylation has emerged as a major mechanism in regulating cellular metabolism. Whereas most glycolytic steps are reversible, the reaction catalyzed by pyruvate kinase is irreversible, and ...the reverse reaction requires phosphoenolpyruvate carboxykinase (PEPCK1) to commit for gluconeogenesis. Here, we show that acetylation regulates the stability of the gluconeogenic rate-limiting enzyme PEPCK1, thereby modulating cellular response to glucose. High glucose destabilizes PEPCK1 by stimulating its acetylation. PEPCK1 is acetylated by the P300 acetyltransferase, and this acetylation stimulates the interaction between PEPCK1 and UBR5, a HECT domain containing E3 ubiquitin ligase, therefore promoting PEPCK1 ubiquitinylation and degradation. Conversely, SIRT2 deacetylates and stabilizes PEPCK1. These observations represent an example that acetylation targets a metabolic enzyme to a specific E3 ligase in response to metabolic condition changes. Given that increased levels of PEPCK are linked with type II diabetes, this study also identifies potential therapeutic targets for diabetes.
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► Glucose destabilizes PEPCK1 by inducing its acetylation ► P300 and SIRT2 regulate PEPCK1 acetylation ► UBR5 ubiquitinates the acetylated PEPCK1
A good regio- and stereoselectivity was observed for the PdCl2-catalyzed cyclocarbonylation of 2-alkynols with CuCl2 affording (Z)-α-chloroalkylidene-β-lactones. The highly optically active ...(Z)-α-chloroalkylidene-β-lactones could be easily prepared from the readily available optically active propargylic alcohols. The Pd(II)-catalyzed cyclocarbonylation of 2-alkynols with CuBr2 was also studied. Although the yields of (Z)-α-bromoalkylidene-β-lactones were low, due to the relatively higher activity of the C−Br bond, the coupling reactions of (Z)-α-bromoalkylidene-β-lactones were quite smooth to afford the corresponding products in high yields. A rationale for this reaction is discussed.
A New Method of Baffle Design Chao, Mei; Sizhong, Zhou; Ming, Ma ...
Procedia engineering,
2011, 2011-00-00, Letnik:
15
Journal Article
Recenzirano
Odprti dostop
Nowadays, as the development of the level of the land observation technology constantly improved, the demanded of the image quality are increasing rise. There are so many possibility factors which ...may influences of the image quality, especially in the inferred optical system, the main reason of them is stray light. The baffle is the main element in the observe system which can inhibit the stray lights that comes from out side of the system. The paper will show you an new idea in baffle design, we put the block aura in an angle which is not 90 degree in conventional. The design can keeps the stray lights out of the system or been greatly absorbed on the condition of low absorption rate of the baffle. We will show you the evidences of calculation, and gave you the basis of the design.
The malate–aspartate shuttle is indispensable for the net transfer of cytosolic NADH into mitochondria to maintain a high rate of glycolysis and to support rapid tumor cell growth. The ...malate–aspartate shuttle is operated by two pairs of enzymes that localize to the mitochondria and cytoplasm, glutamate oxaloacetate transaminases (GOT), and malate dehydrogenases (MDH). Here, we show that mitochondrial GOT2 is acetylated and that deacetylation depends on mitochondrial SIRT3. We have identified that acetylation occurs at three lysine residues, K159, K185, and K404 (3K), and enhances the association between GOT2 and MDH2. The GOT2 acetylation at these three residues promotes the net transfer of cytosolic NADH into mitochondria and changes the mitochondrial NADH/NAD+ redox state to support ATP production. Additionally, GOT2 3K acetylation stimulates NADPH production to suppress ROS and to protect cells from oxidative damage. Moreover, GOT2 3K acetylation promotes pancreatic cell proliferation and tumor growth in vivo. Finally, we show that GOT2 K159 acetylation is increased in human pancreatic tumors, which correlates with reduced SIRT3 expression. Our study uncovers a previously unknown mechanism by which GOT2 acetylation stimulates the malate–aspartate NADH shuttle activity and oxidative protection.
Synopsis
Acetylation of oxaloacetate transaminase (GOT2) promotes its binding with malate dehydrogenase (MDH2), thereby regulating the malate–aspartate shuttle activity, cytosol‐to‐mitochondrion transfer of NADH, oxidative protection and tumor growth.
GOT2 acetylation at three lysine residues enhances its association with MDH2.
SIRT3 is the major deacetylase of GOT2.
Acetylation of GOT2 modulates mitochondrial NADH/NAD+ redox status, energy production, and cell survival during oxidative stress.
GOT2 K159 acetylation is increased in human pancreatic tumors, correlating with reduced SIRT3 expression.
Acetylation of oxaloacetate transaminase (GOT2) promotes its binding with malate dehydrogenase (MDH2), thereby regulating the malate–aspartate shuttle activity, cytosol‐to‐mitochondrion transfer of NADH, oxidative protection and tumor growth.
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