Objective: To prepare the bone morphogenetic protein- 2/pearl powder/chitosan composite scaffolds and observe biological properties. Methods: The bone morphogenetic protein-2/pearl powder/chitosan porous scaffolds were prepared by freeze-drying. The surface properties, the porosity, and the thermal stability of the stent were observed by light microscopy and scanning electron microscopy(SEM), pycnometer, and TGA respectively. Then the rabbit bone marrow mesenchymal stem cells were co-cultured with the stent to detect cell adhesion properties, and inflammatory reaction was observed by burying the stent in subcuticle of rats. Results and conclusion: The results showed that the pore size of bone morphogenetic protein 2/pearl powder/chitosan scaffold ranged between 100μm and 300μm with porosity being 91.64% and compressive stresses up to 3.37MPa. The stent,had suitable cell adhesion properties, and the histocompatibility is predominant, suggesting that the stent may be used as Bone Tissue Engineering materials applied for clinical repairment for bone tissue defects.
The effect of proline hydroxylation on the thermal stability of collagen was investigated. Skin collagen from BN rats with different weeks were separated and purified. The hydroxyproline (Hyp) content in these collagen were analyzed. The influence of hydroxyproline content on the denaturation process of collagen were investigated using the differential scanning calorimeter (DSC) and the circular dichroism (CD) spectroscopy. The CD spectra indicated that collagen obtained from rat skin had the secondary structure typical for collagen. The helix content decreased when denatured by heat treatment. The denaturation temperature and molar enthalpy change was determined using DSC. The results show that the triple-helix become disordered at 41.3℃(Tm). The molar enthalpy change increased with quantity of hydroxylation of proline. CD spectrum manifested that part of the triple-helix changed into random coil structure when the denaturation temperature was higher than 41.3℃. The result indicates that the hydroxylation of proline modification is the key factor affecting on the structure of collagen during denaturation process.
In order to obtain normal growth and resistant drought transgenic potato, using Arabidopsis thaliana (Columbia ecotype) as material, DNA sequence of AtRd29A gene ATG upstream from +83bp to -1 441bp is cloned with PCR and recombinant DNA technologies. The sequence of bases was entirely consistent with that of promoter of the known gene. The plant expression vector pCHFRd-CDPK1 of AtCDPK1 gene drived by Rd29A promoter was constructed, and transformed pCHFRd-CDPK1 into virus-free miniature of potato cultivar‘Favorita’using Agrobacterium-mediated method. After plant selection and regeneration, regenerated plants with resistance were obtained successfully. The PCR and Southern blotting analysis proved that the AtCDPK1 gene has been integrated in the genome of the potato. After drought stress using 30% PEG, RT-PCR analysis proved that the transcript levels of AtCDPK1 gene drived by Rd29A promoter in transgenic potato plants were significantly higher. AtCDPK1 gene drived by Rd29A promoter in transgenic potato plants is barely detectable in the water treatment control. However, expression of AtCDPK1 gene drived by 35S promoter did not make significant difference in transgenic potato plants between PEG stress treatment and water treatment. Morphological observation showed that transgenic plants can grow normally after 30% PEG stress, the plants growing was better than non-transgenic plants, and control plants occur slightly wilt. This research will lay the foundation for further improved stress tolerance of crops by expression of resistant gene drived by stress-inducible promoter in the crop.
Objective: The biosynthesis cluster (ste) of a novel exololysaccharide called Ebosin producing by Streptomyces had been identified previously,that ste3 and ste4 maybe encode a membrane spanning protein probably for sugar import on the basis of bioinformatics analysis. This work studied If ste3 and ste4 were involved in Ebosin biosynthesis. Methods: the ste3 and ste4 genes were disrupted together with a double crossover via homologous recombination. The mutant strain was identified by southern blot and gene complementation also performed. The production of Ebosin through isolating it from wild type, mutant and complementation was analyzed. Results: Ebosin isolated from the supernatants of fermentation cultures of the mutant strain was 153mg/L, remarkably lower than that of the wild-type strain (319mg/L). Complementation of the mutant strain resulted in a recovery of the EPS production (299mg/L) comparing with the wild-type strain. Conclusion: This research firstly elucidate that genes ste3 and ste4 encoding a membrane spanning protein involved in Ebosin biosynthesis and lay the foundation for studying the relationship between primary and second metabolism of Streptomyces sp. 139.
Objective: To compare the inhibitory effects of bortezomib and several natural compounds on HBV in vitro and to explore the molecular mechanism of bortezomib inhibiting HBV in the primary hepatocytes of HBV-Tg mice.Method: Observing toxicity of drugs with different concentrations on HBV-Tg mice primary liver cells and determine the maximum non-toxic concentration through MTT assay. Cultivated and detected the changes of HBsAg in the supernatant of cells after treated with drugs for 24h by ELISA.Bortezomib with 1μmol/L treated primary liver cells for 24h, the total proteins were extracted from the treated cells,and after the proteins were separated by the dimensional gel electrophoresis the differentially expressed protein spots were found.RT-PCR and West blot were used to verify the selected differentially expressed proteins.Results: Among the 8 kinds of natural compounds,pristimerin has the strongest inhibition of HBV, with IC50 being 0.43μmol/L. The IC50 of EGCG being 24.9μmol/L was with good safety. 21 differential spots were found through analyzing the proteome on primary hepatic protein treated with bortezomib, and the HSP60 isomers (gi/26353954)was determined in the meantime. The gene expression of HSP60 and 90 was down-regulated while HSP70 was up-regulated with RT-PCR,but HSP60 changed little in the protein level with West blot after treated bortezomib on HBV-Tg primary hepatocytes .On the other hand, the inhibition of HSP90 by EGCG was consistent with that of HBsAg.Conclusion: Regulation of protein degradation and folding of host cells will be beneficial to the search for new anti-HBV drugs.
A strain of phosphate solubilizing yeast Pichia farinose FL7 that exhibited strong solubilizing capacity to calcium, aluminum and iron phosphate was studied for its application in the phytoextraction of nickel contaminated soil. The phosphate solubilizing capacity to Ni3(PO4)2 and the nickel tolerance to Ni(NO3)2 of P. farinose FL7 were characterized under liquid conditions. Then P. farinose FL7 bioinoculant was prepared and used in the phytoextraction of Ni(NO3)2 and Ni3(PO4)2 contaminated soil with Brassica juncea as the hyperaccumulator. P. farinose FL7 could directly solubilize PO43- from Ni3(PO4)2 more than 10 folds greater than the control without inoculation and showed higher nickel tolerance. The results of greenhouse pot experiment revealed that the addition of P. farinose FL7 significantly increased Ni accumulation in B. juncea. The total biomass of B. juncea was promoted by the inoculation treatment, which increased from (0.23±0.01)g to (0.34±0.01)g. The changes of soil available phosphate and nickel speciation under different treatments indicated that inoculation of P. farinose FL7 increased the immobilization of soluble nickel in Ni(NO3)2 spiked soil and that biofertilization also increased the bioavailability of insoluble nickel in Ni3(PO4)2 spiked soil. P. farinose FL7 showed dual function and could resulted in improved decontamination rates during the microbe-assisted phytoextraction of Ni contaminated soils.
The effects of initial glucose concentrations on cell growth of Monoraphidium sp.FXY-10 under mixotrophic and heterotrophic cultivations were investigated by Andrew equation.A kinetic model was developed to describe the dynamics of glucose consumption for FXY-10 growth. Meanwhile,the influence of different glucose concentrations on the production of lipid by FXY-10 was studied. And the kinetic models of FXY-10 lipid synthesis in the different trophic types with the most appropriate glucose concentration were also constructed. The results showed thatwhen the concentration of glucose was 10g/L, the maximum total lipid content and biomass concentration were achieved under mixotrophic and heterotrophic conditions. The semi-saturation constants of Monoraphidium sp. FXY-10 to glucose in the mixotrophic(KSJ) and heterotrophic (KSY)conditions were 1.89g/L and 17.82g/L, respectively. It implied that the glucose absorption capacity of FXY-10 in the mixotrophic condition was relatively higher than that in the heterotrophic.
β-agonists are phenylethanolamines with different substituent groups on the aromatic ring and the terminal amino group which have the effect of nutrition redistribution and could accumulate in body tissues causing acute or chronic poisoning when consumed. Therefore, establishing a method for rapid screening of β-agonists is very important to food safety control. The aptamer named AP-Ago is screened by Isothermal Titration Calorimetric method. AP-Ago is a single-strand DNA and 22 base-pairs. The dissociation constant (Kd) to PHL is 3.34×10-5 mol/L. A labeled free electrochemical aptasensor is developed with AP-Ago, which is sensitive to phenylethanolamine (PHL), clenbuterol (CLB), ractopamine (RAC), salbutamol (SAL) and procaterol (PRO). The detection limits are 0.04ng/ml (RAC), 0.35pg/ml (CLB), 1.0pg/ml (PHL), 0.53pg/ml (SAL) and 1.73pg/ml (PRO), respectively. The detection time is 15min. This aptasensor also have a good reproductivity of the relative standard deviation (RSD) at 2.09%. The aptasensor can be developed as a rapid screening means with β-agonists (may be one or more) in sample.
The total lipids extracted from microalgae are different from the plant lipids, which are whole-cell extracts. The composition is very complex, existing low polar compounds similar with triglycerides (TAG) on chromatographic retention properties. A rapid and efficient method for determination of neutral lipids in microalgae using HPLC-ELSD was developed by optimizing the analytical columns. The chromatographic separation was performed on a Diol analytical column (250mm×4.6mm, 5μm) by the gradient elution with hexane and isopropanol. The calibration of TAG, free fatty acid (FFA), diacylglycerol (DAG) and moacylglycerol (MAG) showed good linearity. The recoveries of TAG spiked in I. zhangjiangensis and N. oceanica IMET1 were in the range of 96.2%～113.1% and the relative standard deviations 0.46%～4.8%. This method was applied to determine the TAG content of I. zhangjiangensis and N. oceanica IMET1 and compared with traditional solid-phase extraction (SPE) and the common used TLC/GC method. Compared with the above two methods, this method is simple and accurate for the determination of TAG in microalgae.
Autophagy is one of the lysosomal degradation pathways, which plays critical roles in multiple physiological processes in eukaryotes. In recent years, it has been believed that autophagy is tightly involved in tumorigenesis and development. The effects of autophagy on cancer are controversial. Autophagy prevents cells from oxidative stress, persistent inflammation, and DNA damage accumulation during carcinogenesis, and eventually inhibits the development of cancer. However, autophagy also provides growth metabolites needed for tumour cells, and maintains the balance of the intracellular environment, thus promoting carcinogenesis. Autophagy also has double-edged effects on cancer therapy: on one hand, induction of autophagy prevents the accumulation of DNA damages and mutations induced by chemotherapy or radiotherapy, and then inhibits cancer progression; on the other hand, autophagy is required for tumor cells to relieve drug and irradiation therapeutic pressures, and potentially contributes to the survival of tumor cells.
Along with the dramatic advances in sequencing technology, whole genome sequences of more and more species have obtained. Faced with such a status, site-directed genome editing technique has been adapted as an efficient gene-targeting technology to obtain the gene function and application information. CRISPR/Cas9 is the most effective editing technique by far. CRISPR/Cas9 (clustered regularly interspaced short palindromic repeats/CRISPR-associated) refers to an adaptive immune system that is gained from the long-term evolution of the organism which is widespread in bacteria and archaea. The characteristics and development, as well as the application prospect of the technique are summarizzed.
Exopolysaccharides (EPS)of lactic acid bacteria (LAB)are natural polymers produced by LAB. As a new type of natural food additives, EPS of LAB catch the attention of researchers by its immense physiological function and industrial potential. But due to the differences between the composition and function of EPS, It is difficult to establish universal methods and criterions of detection. Also, how to improve the yield of EPS is a great challenge.The genetics of EPS, structure analysis, structure-function relationship, biological activity and further researches will be summarized.
Alternaria Nees which can produce at least 9 HST, are one of the most cosmopolitan fungus. According to different hosts, seven of Alternaria Nees are considered distinct pathotypes of Alternaria alternata. Each pathotype produces specific HST, a diverse group of low-molecular-weight secondary metabolites, which is toxic to susceptible cultivars, but not to resistant cultivars. The genes participating in HST biosynthesis are multi-cope genes which constitute gene clusters. These gene clusters are located on a <2.0Mb CD chromosome which determines the pathogenicity of the A.alternate. The inherent instability of the chromosomes does not affect hypha growth or conidium germination, but does affect the disease-causing capacity on host plants. The HST biosynthetic genes have been isolated from six pathotypes of A.alternate. HST produced by the Japanese pear, strawberry and tangerine pathotype have a common structural moiety, EDA, and these three pathotypes share common genes required for EDA biosynthesis. Studies of the molecular genetics of HST production have provided new insights into the evolution of A.alternata pathotypes.
Objective: The recent progress in research of Chlorella on the production of diodiesel is introduced as a review. Methods: The domestic and international articles on the biodiesel production from chlorella were reviewed and summarized. Results: Microalgae biodiesel is one of the most promising biodiesel. Chiorella is an attractive microalgae spicies for biodiesel production. As its high quality for biodiesel, Chlorella has outstanding advantages compared with other biodiesel raw materials. With the development of engineering technology and the relevant research, Obtaining lipids with both high-quality and large quantity by exploring the appropriate chlorella culture methods will be futfilled in the near future. Conclusion: Chlorella has a widely promising future in the production of diodiesel.
The application of the immobilized enzyme technology improve the stability and reusability of enzyme,which provide conditions for the large-scale use of enzyme in industry.The carrier is one of the key links in the immobilized enzyme technologies,and has become a research focus for immobilized enzyme technology at present.The advantages and disadvantages of mesoporous materials,nano-materials,magnetic materials and natural polymer materials are introduced,while their research status and application results are mentioned.Some methods of analysis and measurement for carrier materials are reviewed including morphology analysis,structure analysis, element analysis,specific surface area and pore size analysis,and the next research orientation and aim are summarized prospectively,which provides the reference for the further study and rational utilization of immobilized enzyme carrier.
Faced with the increasingly serious food situation of supply and demand, accelerating biological breeding technology research has become the preferred solution to the problem. Technology landscape analysis is used to analyze patent information in the field of corn bio-breeding technology, respectively from perspectives of patent cooperation landscape, hot technologies landscape and technology topic landscape. Derwent Innovation Index is selected as a data source. The results shows that crop bio-breeding technology is mainly used in the field of characteristics of the maize varieties conversion, cross maize, gene locus and genetically modified corn. It also provides the basis for the development of Chinese corn biological breeding technology.
