Abstract:Plant type III polyketide synthase (PKS) generates backbones of a variety of plant secondary metabolites with diverse functions, and has long been models to elucidate the relationship between the three-dimensional structure and function. More than 80 type III PKS crystal structures with different functions have been reported in Protein Data Bank, including the crystal structures of the well-studied Chalcone Synthase of plant type III PKS, as well as the 6 other kinds of PKSs in the family, which are critical for understanding the structural basis for diverse starter molecule selectivity, polyketide chain length and the cyclization reaction. Structure-based analysis and site-directed mutagenesis are foundation for the investigation of enzyme engineering, genetic and metabolic engineering. This review summarized 7 plant-specific type III PKS in the aspects of their crystal structures and functions.

Abstract:Tissue engineering technology provides a new method to repair ill tissue and worn-out organs. In tissue engineering, scaffolds play an important role in supporting cell growth, inducing tissue regeneration, controlling tissue structure and releasing active factor. In the last decade, electrospinning technology developed rapidly and opened vast application fields for scaffolds. In this review, we summarized the technological conditions of electrospinning for scaffolds, the study of electrospun fiber scaffolds applied in tissue cell cultivation, and some new directions of electrospinning technology for scaffolds. We also addressed development directions of electrospinning research for scaffolds.

Abstract:RNA interference (RNAi) is a promising technology in development of specific antiviral therapy, but the quantitative detection of small interfering RNA (siRNA) expressed in vivo is the main challenge to assess its antiviral effect. In order to detect the siRNA molecules (siN1 and SiN2) particularly expressed in cells to inhibit the replication of classical swine fever virus (CSFV), serial specific stem-loop primers were designed and synthesized. Two of them (SLP-N1-6 and SLP-N2-8) were selected by screening in cross combination and successfully used in establishment of an optimal stem-loop RT-qPCR, which showed high specificity and sensitivity in detection of anti-CSFV siRNA expressed in PK-15 cells. The method was capable of detecting 102 to 108 copies of siRNA molecule with good parallel relationship (Rsq=0.999) and high amplification efficiency (Eff. = 98.2%). Therefore, the established stem-loop RT-qPCR can be used as an ideal tool in quantitative assessment of the anti-CSFV effects of RNAi in combination with detection of viral antigens using indirect immunofluorescent assay and TCID50, providing a novel technique for evaluating the antiviral effects of the siRNA expressed in anti-CSFV transgenic pigs to be established in future.

Abstract:Co-fermentation of glucose and xylose is critical for cellulosic ethanol, as xylose is the second most abundant sugar in lignocellulosic hydrolysate. In this study, a xylose-utilizing recombinant Zymomonas mobilis TSH01 was constructed by gene cloning, and ethanol fermentation of the recombinant was evaluated under batch fermentation conditions with a fermentation time of 72 h. When the medium containing 8% glucose or xylose, was tested, all glucose and 98.9% xylose were consumed, with 87.8% and 78.3% ethanol yield, respectively. Furthermore, the medium containing glucose and xylose, each at a concentration of 8%, was tested, and 98.5% and 97.4% of glucose and xylose was fermented, with an ethanol yield of 94.9%. As for the hydrolysate of corn stover containing 3.2% glucose and 3.5% xylose, all glucose and 92.3% xylose were consumed, with an ethanol yield of 91.5%. In addition, monopotassium phosphate can facilitate the consumption of xylose and enhance ethanol yield.

Abstract:4-hydroxybutyric acid (4HB) is a psychotropic drug used for polymer synthesis such as poly (4-hydroxybutyric acid) (P4HB) and poly (3-hydroxybutyric acid-co-4-hydroxybutyric acid) (P3HB-co-4HB). 1,4-butanediol (BD) can be converted to 4-hydroxybutyric acid by alcohol dehydrogenase (DhaT) and aldehyde dehydrogenase (AldD). In this study, high efficiency promoters including T7 promoter and PRe promoter were cloned to increase expression of dhaT and aldD, and thus accelerate the conversion from BD to 4HB. A. hydrophila 4AK4 (pZQ01), the recombinant strain under the control of T7 promoter, produced 6.00 g/L 4HB from 10 g/L BD with the productivity increased by 43.20%. While A. hydrophila 4AK4 (pZQ04), the strain under the control of T7 promoter, produced 4.87 g/L 4HB from 10 g/L BD, and the productivity was increased by 16.23%. Thus, the gene expression was increased by T7 and PRe promoters, leading to an accelerated biosynthesis of 4HB.

Abstract:The objective of this work is to investigate how dilution rate and carbon-to-nitrogen (C/N) ratio affects lipid accumulation by Rhodosporidium toruloides AS 2.138 9 in continuous culture. Under steady-state conditions, the increase in dilution rate led to the decrease in lipid content and lipid yield. The highest lipid yield and lipid content at D=0.02 h?1 were 0.18 g lipid/g sugar and 57.1%, respectively, while the highest lipid productivity and biomass productivity were obtained at D=0.14 h?1. The increase in C/N ratio led to the increase in lipid content. The highest lipid content of 38% was obtained at C/N=237. The highest lipid yield of 0.12 g lipid/g sugar was obtained at C/N=92. However, the highest lipid productivity of 0.12 g/(L·h) was obtained at C/N=32. No significant changes were observed in terms of fatty acid composition of the lipid produced under different C/N ratios, and these three fatty acids, palmitic acid, stearic acid and oleic acid, took over 85% in all samples.

Abstract:In order to enhance γ-aminobutyric acid production from L-glutamate efficiently, we amplified the key enzyme glutamate decarboxylase (GAD) encoding gene lpgad from the strain Lactobacillus plantarum GB 01-21 which was obtained by way of multi-mutagenesis and overexpressed it in E. coli BL21. Then we purified GAD by Ni-NTA affinity chromatography and characterized the enzyme to optimize the conditions of the whole-cell transformation. The results show that the recombinant E. coli BL21 (pET-28a-lpgad) produced 8.53 U/mg GAD, which was increased by 3.24 fold compared with the GAD activity in L. plantarum. The optimum pH and temperature of the enzyme were pH 4.8 and 37 °C, respectively. At the same time, we found that Ca2+ and Mg2+ could increase the activity significantly. Based on this, we investigated γ-aminobutyric acid transformation in 5 L fermentor under the optimum transformation conditions. Accordingly, the yield of γ-aminobutyric acid was 204.5 g/L at 24 h when the 600 g L-glutamate was added and the mole conversion rate had reached 97.92%. The production of γ-aminobutyric acid was improved by 42.5% compared with that under the unoptimized transformation conditions. This paved a way for the γ-aminobutyric acid construction of the industrial applications.

Abstract:To develop a method based on immunoreactions for detection of Ectropis obliqua Nucleopolyhedrovirus (EoNPV), the polyhedra of the virus were purified and used to immunize the mouse BALB/c. The spleen cells from the immunized mice were then fused with the myeloma cell line Sp2/0. A hybridoma cell line which can stably secrete the monoclonal antibody against EoNPV was achieved by using indirect ELISA screening and cloning methods, and was named as 7D3. Meanwhile, the polyhedrin gene was cloned from EoNPV and expressed in E. coli. Western blotting analysis showed that the monoclonal antibody prepared from 7D3 could specifically react with the recombinant polyhedrin. An indirect ELISA method based on this monoclonal antibody for detecting EoNPV in infected tea looper was developed.

Abstract:Ammopiptanthus mongolicus shows very strong resistance to severe environments. To isolate drought-resistant genes and elucidate drought-resistant molecular mechanisms of the plant, we constructed a drought-induced full-length cDNA library using SMART (Switching mechanism at 5￠-end of RNA transcript) technique. The phage titer of the unamplified library was 1.6×107 PFU/mL; the recombination percentage was 97.7%; and the sizes of most cloned cDNA fragments were around 1 kb. Three thousand positive clones were randomly selected and sequenced from their 5￠ ends, and a total of 1 450 Unigenes were identified. By Blast searches against the Nt, Nr and Swissprot databases, we found that 919 Unigenes (amount to 63.4%) showed significant similarity to the annotated genes, and the remaining 531 Unigenes (amount to 36.6%) represented novel genes without any annotation. Among the functional categories of the GO (Gene Ontology) classification, the terms related to physiological process, cellular process, binding, catalytic activity and cellular components were dominant. The next abundant terms were for organelle, protein complex, transporter activity and structural molecule activity. In addition, there were a significant proportion of the terms involved in stimulus response, gene expression regulation, regulation of physiological and biochemical processes and signal transduction. Many of the annotated Unigenes were found to be related to plant resistance to abiotic stresses, and expression analyses of 6 out of these genes by semi-quantitive RT-PCR confirmed their involvements in the response of A. mongolicus to drought stress. These results laid a foundation for the expression profile analysis and the cloning and characterization of drought-resistant genes from the plant in the future.

Abstract:Recent years, the incidence and mortality of prostate cancer have increased dramatically in China. At earlier stages, most diagnosed prostate cancers are responsive to androgen depletion treatment, yet, nearly all patients will eventually progress to metastatic androgen-independent prostate cancer (AIPC), which still has no effective therapeutic method or drug to deal with. 11'-Deoxyverticillin A (C42) belongs to the family of epipolythiodioxopiperazines (ETPs), an interesting class of fungal toxins that inhibit farnesyl transferase. Compounds holding such a property have been explored as putative anticancer agents. In this study, using PC3M cells, an AIPC cell line, we investigated the effect of the compound on apoptosis and explored the underlying mechanism. It revealed that C42 markedly enhanced the activity of caspase-3/7 and increased the accumulation of the cleaved PARP, all of which are the markers of apoptosis. It also revealed that C42 either decreased cell viability or inhibited the growth of PC3M cells. Moreover, we observed that the loss of cell viability and cell growth inhibition induced by C42 were both time- and dosage dependent. Taken together, we indicated that C42 can induce caspase-dependent apoptosis in AIPC cells, and the results presented here will broaden our knowledge about the molecular mechanisms by which C42 exerts its anticancer activity, and future work in this direction may provide valuable information in the development of these compounds into effective cancer therapeutic strategies against androgen-independent prostate cancer.

Abstract:Cloning of flanking sequences of double-copy gene is a challenge in molecular biology. We developed a method to solve this problem by combining an optimized inverse PCR (iPCR) with TAIL-PCR. First, Southern blotting analysis was used to determine a proper restriction enzyme that could obtain proper-length restriction fragments that contained the target gene. Then optimized iPCR was performed to amplify the restriction fragments that contained the separated copies of the gene. Based on the obtained sequences, TAIL-PCR was performed to amplify further flanking regions of the gene. With this method, we obtained all of the EcoR I restriction fragments (2.2–5.1 kb) and Hind Ⅲ restriction fragments (8.5–11.7 kb) of mitochondrial atpA gene in cytoplasmic male sterile (CMS) line and maintainer line of Upland cotton. The results showed that this method was an efficient approach to clone flanking sequences of double-copy gene.