大肠杆菌中核黄素的底物合成途径改造及生产（英文）

3,4-Dihydroxy-2-butanone 4-phosphate(DHBP) and GTP are the precursors for riboflavin biosynthesis.In this research,improving the precursor supply for riboflavin production was attempted by overexpressing ribB and engineering purine pathway in a riboflavin-producing Escherichia coli strain.Initially,ribB gene was overexpressed to increase the flux from ribulose 5-phosphate(Ru-5-P) to DHBP.Then ndk and gmk genes were overexpressed to enhance GTP supply.Subsequently,a R419 L mutation was introduced into purA to reduce the flux from IMP to AMP.Finally,co-overexpression of mutant purF and prs genes further increased riboflavin production.The final strain RF18 S produced 387.6 mg riboflavin ·L^(-1) with a yield of 44.8 mg riboflavin per gram glucose in shake-flask fermentations.The final titer and yield were 72.2%and 55.6%higher than those of RF01 S,respectively.It was concluded that simultaneously engineering the DHBP synthase and GTP biosynthetic pathway by rational metabolic engineering can efficiently boost riboflavin production in E.coli.

A novel negative regulatory mechanism of Smurf2 in BMP/Smad signaling in bone

Transforming growth factor-β(TGF-β)and bone morphogenetic protein(BMP)play important roles in bone metabolism.Smad ubiquitination regulatory factors(Smurfs)regulate TGF-β/BMP signaling via ubiquitination,resulting in degradation of signaling molecules to prevent excessive activation of TGF-β/BMP signaling.Though Smurf2 has been shown to negatively regulate TGF-β/Smad signaling,its involvement in BMP/Smad signaling in bone metabolism has not been thoroughly investigated.In the present study,we sought to evaluate the role of Smurf2 in BMP/Smad signaling in bone metabolism.Absorbable collagen sponges containing 3μg of recombinant human BMP2(rhBMP2)were implanted in the dorsal muscle pouches of wild type(WT)and Smurf2−/−mice.The rhBMP2-induced ectopic bone in Smurf2−/−mice showed greater bone mass,higher mineral apposition and bone formation rates,and greater osteoblast numbers than the ectopic bone in WT mice.In WT mice,the ectopic bone consisted of a thin discontinuous outer cortical shell and scant inner trabecular bone.In contrast,in Smurf2−/−mice,the induced bone consisted of a thick,continuous outer cortical shell and abundant inner trabecular bone.Additionally,rhBMP2-stimulated bone marrow stromal cells(BMSCs)from Smurf2−/−mice showed increased osteogenic differentiation.Smurf2 induced the ubiquitination of Smad1/5.BMP/Smad signaling was enhanced in Smurf2−/−BMSCs stimulated with rhBMP2,and the inhibition of BMP/Smad signaling suppressed osteogenic differentiation of these BMSCs.These findings demonstrate that Smurf2 negatively regulates BMP/Smad signaling,thereby identifying a new regulatory mechanism in bone metabolism.

Leaf photosynthesis and yield components of mung bean under fully open-air elevated[CO_2]

Mung bean（Vigna radiata L.） has the potential to establish symbiosis with rhizobia,and symbiotic association of soil micro flora may facilitate the photosynthesis and plant growth response to elevated[CO2].Mung bean was grown at either ambient CO2 400 μmol mol^（-1） or[CO2]（（550＋17） μmol mol^（-1）） under free air carbon dioxide enrichment（FACE） experimental facility in North China.Elevated[CO2]increased net photosynthetic rate（Pn）,water use efficiency（WUE） and the non-photochemical quenching（NPQ） of upper most fully-expanded leaves,but decreased stomatal conductance（Gs）,intrinsic efficiency of PSII（Fv ＇/Fm＇）,quantum yield of PSII（φ（PSll）） and proportion of open PSII reaction centers（qp）.At elevated[CO2],the decrease of Fv＇/Fm＇,φ（PSII）,qp at the bloom stage were smaller than that at the pod stage.On the other hand,Pn was increased at elevated[CO2]by 18.7 and 7.4%at full bloom（R2） and pod maturity stages（R4）,respectively.From these findings,we concluded that as a legume despite greater nutrient supply to the carbon assimilation at elevated[CO2],photosynthetic capacity of mung bean was still suppressed under elevated[CO2]particularly at pod maturity stage but plant biomass and yield was increased by 11.6 and 14.2%,respectively.Further,these findings suggest that even under higher nutrient acquisition systems such as legumes,nutrient assimilation does not match carbon assimilation under elevated[CO2]and leads photosynthesis down-regulation to elevated[CO2].

Building Expertise on FAIR Through Evolving Bring Your Own Data(BYOD) Workshops: Describing the Data, Software, and Management-focused Approaches and Their Evolution

Since 2014,"Bring Your Own Data"workshops(BYODs)have been organised to inform people about the process and benefits of making resources Findable,Accessible,Interoperable,and Reusable(FAIR,and the FAIRification process).The BYOD workshops'content and format differ depending on their goal,context,and the background and needs of participants.Data-focused BYODs educate domain experts on how to make their data FAIR to find new answers to research questions.Management-focused BYODs promote the benefits of making data FAIR and instruct project managers and policy-makers on the characteristics of FAIRification projects.Software-focused BYODs gather software developers and experts on FAIR to implement or improve software resources that are used to support FAIRification.Overall,these BYODs intend to foster collaboration between different types of stakeholders involved in data management,curation,and reuse(e.g.domain experts,trainers,developers,data owners,data analysts,FAIR experts).The BYODs also serve as an opportunity to learn what kind of support for FAIRification is needed from different communities and to develop teaching materials based on practical examples and experience.In this paper,we detail the three different structures of the BYODs and describe examples of early BYODs related to plant breeding data,and rare disease registries and biobanks,which have shaped the structure of the workshops.We discuss the latest insights into making BYODs more productive by leveraging our almost ten years of training experience in these workshops,including successes and encountered challenges.Finally,we examine how the participants'feedback has motivated the research on FAIR,including the development of workflows and software.

Zinc in plants:Integrating homeostasis and biofortification

Zinc plays many essential roles in life.As a strong Lewis acid that lacks redox activity under environ-mental and cellular conditions,the Zn2+cation is central in determining protein structure and catalytic function of nearly 10%of most eukaryotic proteomes.While specific functions of zinc have been elucidated at a molecular level in a number of plant proteins,wider issues abound with respect to the acquisition and distribution of zinc by plants.An important challenge is to understand how plants balance between Zn supply in soil and their own nutritional requirement for zinc,particularly where edaphic factors lead to a lack of bioavailable zinc or,conversely,an excess of zinc that bears a major risk of phyto-toxicity.Plants are the ultimate source of zinc in the human diet,and human Zn deficiency accounts for over 400000 deaths annually.Here,we review the current understanding of zinc homeostasis in plants from the molecular and physiological perspectives.We provide an overview of approaches pursued so far in Zn biofortification of crops.Finally,we outline a"push-pull"model of zinc nutrition in plants as a simplifying concept.In summary,this review discusses avenues that can potentially deliver wider bene-fits for both plant and human Zn nutrition.

Optimization of a synthetic medium for ethanol production by xylose-fermenting Zymomonas mobilis using response surface methodology

A synthetic medium for ethanol production by recombinant xylose-fermenting Zymomonas mobilis was optimized using Plackett-Burman(PB) design and response surface methodology(RSM).The effects of 19 medium components were investigated by PB design.Eight of these components were determined to have significant effects on ethanol production.The statistical model was constructed via central composite design(CCD) using five selected variables,including xylose,trisodium citrate,choline chloride,pyridoxine,and thiamine.The validity of the developed model was verified.The ethanol concentration in the optimized medium was 6.7% higher than in the RM medium.The optimized medium was then simplified to give the final synthetic medium(S2),in which the ethanol concentration was 20.7% higher than in the RM medium.Xylose and trisodium citrate were the key medium components influencing ethanol production,while calcium pantothenate was the only growth factor required by recombinant Z.mobilis.Ethanol production and growth response were directly proportional to the logarithm of the concentration of trisodium citrate in the range of 0.1-1.6 g/L.

Highly sensitive force measurements in an optically generated, harmonic hydrodynamic trap

The use of optical tweezers to measure forces acting upon microscopic particles has revolutionised fields from material science to cell biology.However,despite optical control capabilities,this technology is highly constrained by the material properties of the probe,and its use may be limited due to concerns about the effect on biological processes.Here we present a novel,optically controlled trapping method based on light-induced hydrodynamic flows.Specifically,we leverage optical control capabilities to convert a translationally invariant topological defect of a flow field into an attractor for colloids in an effectively one-dimensional harmonic,yet freely rotatable system.Circumventing the need to stabilise particle dynamics along an unstable axis,this novel trap closely resembles the isotropic dynamics of optical tweezers.Using magnetic beads,we explicitly show the existence of a linear force-extension relationship that can be used to detect femtoNewton-range forces with sensitivity close to the thermal limit.Our force measurements remove the need for laser-particle contact,while also lifting material constraints,which renders them a particu-larly interesting tool for the life sciences and engineering.