Current Biotechnology

Advances on Plant 3-hydroxy-3-methylglutaryl Coenzyme A Reductase (HMGR) Genes
CHU Wei1,2, LIU Yangyang1,2, LI Yongbo2, CHU Xiusheng2*
2018, 8(2): 93-102. DOI: 10.19586/j.2095-2341.2017.0126
Abstract ( ) PDF (2242KB)( )

Isoprenoids such as cytokinins, gibberellins, abscisic acids, chlorophylls and carotenoids, which are widely exist in plants, play important roles in the growth, development of plants. Some terpenoids used as precursors of drugs or effective medicinal components have vital economic values in agricultural and pharmaceutical production. Isoprenoids are mainly synthesized by a series of enzymes including 3-hydroxy-3-methylglutary CoA reductase (HMGR). HMGR has been considered as the first rate-limited enzyme, which catalyses the conversion of 3-hydroxy-methylglutaryl-CoA (HMG-CoA) to mevalonate. This paper mainly summarized the advances of plant HMGR in the respect of cDNA cloning, gene regulation, gene expression in different tissues of plants, enzyme kinetics study, enzyme structure and functional analysis, which might provide the theory basis for application of HMGR in genetic improvement of major crops, creation of engineering plants highly producing valuable isoprenoids, and determination of plant phylogenetic relationship.

Progress on Synergistic Effects of Various Additives on the Insecticidal Activity of Bacillius thuringiensis
LI Chaofeng
2018, 8(2): 103-111. DOI: 10.19586/j.2095-2341.2017.0158
Abstract ( ) PDF (1526KB)( )

As one of the most widely used and the most effective biopesticides, Bacillius thuringiensis (Bt) preparations are widely employed for pest control in the fields of agriculture, forestry and public health because of the specific insecticidal activity. However, after field application, the further popularization of Bt preparations has been limited due to the disadvantages, such as poor readily availability, short-duration action and unstable control effect. It is the most fast and efficient way by mixing Bt preparations with all sorts of synergistic agents and synergistic factors to improve the insecticidal activity and field control effect stability. Extensive and in-depth researches on synergistic effects of various additives on Bt preparation have been carried out at home and abroad. In this paper, the progress on synergistic effects of chemical additives, chemical insecticides and biopesticides on Bt preparations were reviewed, and the development and application prospects of synergistic agents and synergistic factors were also discussed in order to provide references for developing safe and efficient synergistic agents and synergistic factors of Bt preparations.

Application of Functionalized Mesoporous Silica Nanoparticles in the Diagnosis and Therapy of Malignant Tumors
YU Yi, WAN Chenlu, LIAO Yuxia, HE Zhendan*, LI Ying*
2018, 8(2): 118-123. DOI: 10.19586/j.2095-2341.2017.0153
Abstract ( ) PDF (1165KB)( )

Mesoporous silica nanoparticles have good application prospects in the field of biomedicine as novel nano-carriers. MSNs physical and chemical properties, which are different from traditional inorganic materials, play a key role in the diagnosis and therapy of malignant tumors. In particular, as the drug loading platforms with high loadings, good biocompatibility, targeting ability and the controllability for drug release, the mesoporous silica nanoparticles could be used to solve problems in the clinical diagnosis and therapy of malignant tumors. The application progress and development direction of the nanoprobe and targeted delivery system using MSNs was primarily discussed in order to provide ideas and references for the diagnosis and therapy of malignant tumors.

Identification and Characterization of the COMPACT STALK INTERNODES (COSTIN) Gene Required for Plant Height in Medicago truncatula
LI Hui1§, YIN Pengcheng2§, ZHU Butuo2, LIN Hao2, LIU Zhiqiang1, PEI Yanxi1*, NIU Lifang2*
2018, 8(2): 124-131. DOI: 10.19586/j.2095-2341.2018.0020
Abstract ( ) PDF (6450KB)( )

Plant height is one of the most important agronomic traits that determines the lodging resistance and biomass yield in crops. However, the molecular mechanism underlying the stem elongation in forage legumes is poorly understood. In this study, we isolated and characterized a dwarf mutant compact stalk internodes (costin) by screening Tnt1 retrotransposon-tagged lines of M. truncatula. Results showed that the dwarf phenotype of costin is caused by inhibition of the internode elongation. We cloned COSTIN by PCR-based genotyping of flanking sequence tags (FST) in segregating populations. The COSTIN gene encodes a calcium exchanger protein, which is homologue to Arabidopsis CALCIUM EXCHANGER 7(CAX7). qRT-PCR analysis revealed that COSTIN is highly expressed in stem, leaf and pod. Moreover, several gibberellic acid (GA) biosynthesis pathway genes including MtCPS, MtKAO1, MtGA20ox4, MtGA20ox7 and MtGA3ox1 were significantly downregulated in the costin mutant, and the dwarf phenotype of costin could be rescued by exogenous application with gibberellic acid-3 (GA3). These data together demonstrated that the COSTIN gene control internode elongation through regulating the biosynthesis of the phytohormone gibberellic acid in M. truncatula.

Screening and Identification of a Cellulose Decomposing Fungus and its Degradation Effect on Corn Straw
WANG Jiayou, ZHAO Pengnian, YANG Deyu, LONG Jingjing, ZHOU Yue, WANG Yuan*
2018, 8(2): 132-139. DOI: 10.19586/j.2095-2341.2017.0125
Abstract ( ) PDF (3106KB)( )

In order to screen highly efficient cellulose-decomposing strains for corn straw, the soil samples which corn straw was returned in were collected for enrichment culture at 20℃. The initial screening was carried out by solid isolation medium using corn straw cellulose as the sole carbon source and Congo red staining method, and then the culture supernatants of the screened strains through liquid fermentation were collected and used for determination of enzyme activity. At last, fungus SY-403 with strong production of cellulase was obtained. The strain SY-403 was identified as Talaromyces stollii by morphological characterization and the results of molecular biology identification. The study of its cellulase characterization showed that, the optimum reaction pH was 6.0 and the optimum reaction temperature was 20℃. Under the simulated outdoor conditions (15℃), when corn straw was treated with SY-403 for 40 d, the weight loss rate of corn straw and the decomposition rate of cellulose were 42.67% and 55.26%, respectively. Changes of functional groups during the corn straw degradation process were determined by Fourier transform infrared spectroscopy. And the results showed that the peak area of cellulose (1 052~1 054 cm-1) decreased, while the peak area of hydroxyl (1 328~1 330 cm-1) increased, which indicated that cellulose had been broken down into available short chain structures. The results proved that the strain SY-403 could be used to degrade corn straw.

Study on Diversity of Cultivable Myxobacteria in Wetland Environment
ZHANG Xianjiao, LV Yingying, ZHU Honghui*
2018, 8(2): 140-146. DOI: 10.19586/j.2095-2341.2017.0123
Abstract ( ) PDF (4738KB)( )

Purpose of the work was to isolate myxobacteria from different types of wetland sediment in Guangdong by help-bacteria and filter papers methods. These strains were preliminary identified based on the morphological characteristics and the analysis of 16S rDNA gene sequences. 67 strains were isolated from 84 samples. The pure cultures could be classified into 7 genera: Myxococcus (32 strains), Corallococcus (15 strains), Cystobacter (2 strains), Polyangium (5 strains), Archangium (7 strains), Pyxidicoccus (5 strains) and Hyalangium (1 strain). The results showed that myxobacteria were widely distributed in wetland environment, and lots of uncultured myxobacteria resources existed in this region. This work laid a foundation for further researches on the exploitation of myxobacteria in wetland environment.

Isolation and Identification of Myxobacteria in Virgin Forest of Vietnam
ZHANG Xianjiao, LV Yingying, ZHU Honghui*
2018, 8(2): 147-152. DOI: 10.19586/j.2095-2341.2017.0122
Abstract ( ) PDF (5216KB)( )

Samples of forest soil, rotten wood and bark were collected from virgin forest of Vietnam to investigate the myxobacteria diversity. 70 strains were observed based on the methods of living Escherichia coli and filter papers, and 32 strains were purified finally. These strains were preliminary identified to generic level based on the morphological characteristics and the analysis of 16S rRNA gene sequences. The pure cultures could be classified into 6 genus: Myxococcus (14 strains), Corallococcus (7 strains), Nanncystis (6 strains), Melittangium (3 strains), Archangium (1 strain) and Chondromyces (1 strain). The results showed that there were many rare strains of myxobacteria, which had a wide distribution, in the virgin forest of Vietnam.

Study on Biodegradation Mechanism of Amide by Molecular Simulation
ZHANG Yu1, LIU Zhifeng2, CHEN Ming2, LIU Shijun1, XU Hongbo1, TANG Zhishu1*
2018, 8(2): 153-160. DOI: 10.19586/j.2095-2341.2017.0137
Abstract ( ) PDF (7013KB)( )

In order to explore the microscopic degradation mechanism of amide degrading enzymes, we used molecular docking method to investigate the binding modes of amide to amidase. The theoretical models of their structures were obtained. According to the lowest score function principle, the results showed that the best conformation scoring function between RhAmidase and L-methioninamide were -86.741 9, re-rank scores were -76.022 4. And we used LPC/CSU Server to study the interactions between RhAmidase and L-methioninamide. Results showed that hydrophobic interaction was the strongest contacts in the complex. The amino acid residues ARG256 A, LEU353 A, TYR346 A, ARG225 A, THR218 A and PRO222 A were detected to play significant roles in catalytic processes.

Optimization on Extraction Technology of Polysaccharides from Hibiscus sabdariffa by Response Surface Methodology and Evaluation of its Antioxidant Activity
ZHENG Daheng1,2, WANG Wei2, LI Qian2, CHEN Yao3, ZHANG Weijie2, ZHAO Ting4, YANG Liuqing4*
2018, 8(2): 161-168. DOI: 10.19586/j.2095-2341.2017.0154
Abstract ( ) PDF (5536KB)( )

In this study, the crude polysaccharide was extracted from Hibiscus sabdariffa, and its extraction process and antioxidant activity were also studied. Based on single factor experiments, the response surface methodology (RSM) was employed to further optimize extraction conditions. The optimal extracted parameters were solid-liquid ratio of 1∶26, extraction time of 3.1 h and the extraction temperature of 90℃. Under these conditions, the yield of the crude polysaccharide was 14.41%, which is closed to the predicted value. Meanwhile, it had certain scavenging effect on DPPH free radical, hydroxyl free radical and superoxidant free radical. This process can be applied in the preparation of the polysaccharide. The results provided a scientific basis for researching, developing and utilization of the polysaccharide from Hibiscus sabdariffa.

Effect of Pattern Recognition Receptor Activation State on the p38-MAPK Phosphorylation in Microglia
ZHENG Hanxuan, ZHANG He*
2018, 8(2): 169-173. DOI: 10.19586/j.2095-2341.2017.0140
Abstract ( ) PDF (1208KB)( )

To investigate the effect of pattern recognition receptor(PRR) activation state on Aβ42-induced p38-MAPK phosphorylation and phagocytosis ability in microglia, normal microglia and PRR（SRA，TRL2，SRB，CD36）-blocked microglia was incubated with oligomer form of Aβ42（oAβ42）. The level of p38-MAPK phosphorylation and the effect of the blocking of PRR in microglia on cell uptake of Aβ42 was measured. Results showed that, antibody-blocking SRA and TLR2 receptor reduced the p38-MAPK phosphorylation level induced by Aβ42 significantly, compared with normal microglia. Antibody-blocking toll-like receptor 2(TRL2) neutralization lower the cell uptake of Aβ42, which indicated that the PRR activation state had influenced the phagocytosis ability of microglia, and the process was related with the p38-MAPK phosphorylation level. However，endocytosis inhibiter-treated microglia had no significant influence on oAβ42 uptake amount, which indicated that endocytosis on Aβ42 was not classical endocytosis. Toll-like receptor 2（TLR2）was involved in oAβ42 phagocytosis initiation and would be potential therapeutic target for AD immunotherapy.

A Scarless Knockout Method of ftsZ Gene in Escherichia coli Mediated by Oligonucleotide
ZHANG Feifei1, YANG Yunwen2, DONG Huiqing2, SHANG Guangdong2*
2018, 8(2): 174-179. DOI: 10.19586/j.2095-2341.2017.0130
Abstract ( ) PDF (1691KB)( )

At present, the scarless knockout technology for Escherichia coli have many shortcomings, such as long period, complex operation steps, etc. In order to further improve and optimize the scarless knockout technology, E. coli tubulin-like GTPase gene ftsZ was knocked out via single strand oligonucleotide-mediated recombineering(SSOR) including two-step successive homologous recombination. The rapid and efficient scarless gene knockout method has provided an effective method for the transformation of E. coli genome. In addition, the gene deletion strain of ftsZ has laid the foundation for the study of ftsZ gene function.

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