Characterization of Extracellular Polysaccharides from Nostoc flagelliforme Cells in Liquid Suspension Culture

Jia, Shiru,Yu, Haifeng,Lin, Yongxian,Dai, Yujie Korean Society for Biotechnology and Bioengineerin 2007 Biotechnology and Bioprocess Engineering Vol.12 No.3

Nostoc flagelliforme cells were studied with regard to the physico-chemical characterization of the extracellular polysaccharides (EPS) secreted in a liquid suspension culture. The hydrolyzed EPS were determined to be composed of four neutral sugars, which were glucose (43.2%), xylose (20.6%), galactose (29.9%), and mannose (6.3%). The glucuronic acid was the only uronic acid identified in the residue. The apparent molecular weight was estimated at $2.79{\times}10^5$. The Fourier transform infrared spectra showed that the EPS evidenced characteristics typical of non-sulfated polysaccharides. The UV spectrum and Bradford reaction indicated that there were no nucleic acids and proteins in them. The thermal analysis showed a decomposition peak at $245^{\circ}C$ on the thermogravimetric (TG) curves. The scanning electron microscope (SEM) analysis indicated that the EPS possessed a porous structure. The observed microstructural irregularities indicated that the polysaccharide was a type of amorphous solid. These results showed that the EPS of N. flagelliforme cells might be employed as a substitute for those normally derived from field colonies. The results of this study may prove to be beneficial to the protection of the natural resource represented by N. flagelliforme.

Modeling and Analysis of SEIG-STATCOM Systems Based on the Magnitude-Phase Dynamic Method

Haifeng Wang,Xinzhen Wu,Rui You,Jia Li 전력전자학회 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.3

This paper proposes an analysis method based on the magnitude-phase dynamic theory for isolated power systems with static synchronous compensators (STATCOMs). The stability margin of an isolated power system is greatly reduced when a load is connected, due to the disadvantageous features of the self-excited induction generators (SEIGs). To analyze the control process for system stability and to grasp the dynamic characteristics in different timescales, the relationships between the active/reactive components and the phase/magnitude of the STATCOM output voltage are derived in the natural reference frame based on the magnitude/phase dynamic theory. Then STATCOM equivalent mechanical models in both the voltage time scale and the current time scale are built. The proportional coefficients and the integral coefficients of the control process are converted into damping coefficients, inertia coefficients and stiffness coefficients so that analyzing its controls, dynamic response characteristics as well as impacts on the system operations are easier. The effectiveness of the proposed analysis method is verified by simulation and experimental results.

Modeling and Analysis of SEIG-STATCOM Systems Based on the Magnitude-Phase Dynamic Method

Wang, Haifeng,Wu, Xinzhen,You, Rui,Li, Jia The Korean Institute of Power Electronics 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.3

This paper proposes an analysis method based on the magnitude-phase dynamic theory for isolated power systems with static synchronous compensators (STATCOMs). The stability margin of an isolated power system is greatly reduced when a load is connected, due to the disadvantageous features of the self-excited induction generators (SEIGs). To analyze the control process for system stability and to grasp the dynamic characteristics in different timescales, the relationships between the active/reactive components and the phase/magnitude of the STATCOM output voltage are derived in the natural reference frame based on the magnitude/phase dynamic theory. Then STATCOM equivalent mechanical models in both the voltage time scale and the current time scale are built. The proportional coefficients and the integral coefficients of the control process are converted into damping coefficients, inertia coefficients and stiffness coefficients so that analyzing its controls, dynamic response characteristics as well as impacts on the system operations are easier. The effectiveness of the proposed analysis method is verified by simulation and experimental results.

Characterization of Extracellular Polysaccharides from Nostoc flagelliforme Cells in Liquid Suspension Culture

Shiru Jia,Haifeng Yu,Yongxian Lin,Yujie Dai 한국생물공학회 2007 Biotechnology and Bioprocess Engineering Vol.12 No.3

Nostoc flagelliforme cells were studied with regard to the physico-chemical characterization of the extracellular polysaccharides (EPS) secreted in a liquid suspension culture. The hydrolyzed EPS were determined to be composed of four neutral sugars, which were glucose (43.2%), xylose (20.6%), galactose (29.9%), and mannose (6.3%). The glucuronic acid was the only uronic acid identified in the residue. The apparent molecular weight was estimated at 2.79 × 105. The Fourier transform infrared spectra showed that the EPS evidenced characteristics typical of non-sulfated polysaccharides. The UV spectrum and Bradford reaction indicated that there were no nucleic acids and proteins in them. The thermal analysis showed a decomposition peak at 245oC on the thermogravimetric (TG) curves. The scanning electron microscope (SEM) analysis indicated that the EPS possessed a porous structure. The observed microstructural irregularities indicated that the polysaccharide was a type of amorphous solid. These results showed that the EPS of N. flagelliforme cells might be employed as a substitute for those normally derived from field colonies. The results of this study may prove to be beneficial to the protection of the natural resource represented by N. flagelliforme.

Influence of wheat-walnut intercropping on the Sitobion avenae and its predatory natural enemies

Gao Haifeng,Jia Shuangshuang,Liu Yongqiang,Shen Yuyang,Li Guangkuo,Zhao Sifeng,Ge Feng 한국응용곤충학회 2024 Journal of Asia-Pacific Entomology Vol.27 No.1

Intercropping is widely applied all over the world, and it often causes significant changes in the number of arthropod communities. Walnut-wheat intercropping systems are commonly applied in Southern Xinjiang of China. But it is still not clear how wheat-walnut intercropping influence pest and natural enemy populations, and their ratio in wheat fields. To clarify this question and provide guidance to pest management, field surveys were conducted in Xinjiang during 2017–2019. Three intercropping treatments were tested, which were wheat-walnut 10:6, 25:6, and monoculture wheat. Our results showed that the abundance of predators (mainly ladybeetles and lacewings) increased in wheat under wheat-walnut intercropping systems (especially in intercrop treatment 10:6). Compared with monoculture wheat, the ratio of predators to Sitobion avenae was not enhanced in wheatwalnut intercropping fields. S. avenae populations increased in the walnut intercropped wheat fields. The intercropping system was not beneficial to S. avenae control in wheat fields. Different measures should be taken to strengthen the control of S. avenae in walnut intercropped wheat fields.

Differences in the starvation-induced autophagy response in MDA-MB-231 and MCF-7 breast cancer cells

Wanyun Zhu,Hong-Jiang Wei,Hong-Ye Zhao,Hao Qu,Kaixiang Xu,Baoyu Jia,Haifeng Li,Yimin Du,Guangming Liu 한국통합생물학회 2017 Animal cells and systems Vol.21 No.3

Breast cancer is a heterogeneous disease with distinct subtypes that have made targeted therapy of breast cancer challenging. Previous studies have demonstrated that an altered autophagy capacity can influence the development of breast cancer. However, the molecular differences in starvationinduced autophagic responses in MDA-MB-231 and MCF-7 cells have not been fully elucidated. In this study, we found that an increase of LC3B-II protein expression level and a decrease of the p62 protein expression level in both cells treated by Earle’s balanced salt solution. Meanwhile, we observed an increase of autophagosome using transmission electron microscopy and an enhancement in the green fluorescence intensity of LC3B protein by confocal microscopy. Furthermore, we detected the expression of 13 autophagy-related (ATG) genes and 11 autophagy signaling pathway-related genes using qPCR. Among 13 ATG genes, we found that 6 genes were up-regulated in treated MDA-MB-231 cells, while 4 genes were up-regulated and 1 gene was down-regulated in treated MCF-7 cells. In addition, among 11 autophagy signaling pathway-related genes, 7 genes were up-regulated in treated MDA-MB-231 cells, while 5 genes were up-regulated and 1 gene was down-regulated in treated MCF-7 cells. These findings suggest that the autophagic response to starvation was different in the two treated cell lines, which will contribute to further study on the molecular mechanism of starvation-induced autophagy and improve the targeted therapy of breast cancer.

Integrated metatranscriptome and transcriptome reveals the microbial community composition and physiological function of xylem sap on grapevine during bleeding period

Zheng Ting,Zhang Kekun,Zhu Xudong,Guan Le,Jiu Songtao,Li Xiaopeng,Mazzullah Nasim,Jia Haifeng,Fang Jinggui 한국유전학회 2019 Genes & Genomics Vol.41 No.9

Background The xylem sap of fruit trees ensures the survival during the dormant period, and its flow during the bleeding period is correlated with the start of a new life cycle. Though the simple exploration on ingredients in the sap was carried out in the early years, the specific life activities and physiology functions of the sap during bleeding period have not been reported yet and the bleeding period is still a fruit tree development period worthy of attention. Objectives In this study, the microbial community composition during bleeding period were revealed by metatranscriptome and transcriptomic data. For the first time, the microorganism genome and grape genome in xylem sap were analyzed on transcriptional level, based on which the main physiological functions of the sap were also determined. Methods The genomic RNA in the sap was isolated and sequenced. Kyoto Encyclopedia of Gene and Genome (KEGG), Evolutionary genealogy of genes: Non-supervised Orthologous Groups (eggNOG) and Carbohydrate-Active enzymes Database (CAZy) functional annotation were used to analysis the function of micro-organisms in xylem sap. DEGs were analyzed by gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG). The genes responsive to biotic and abiotic stresses were finally screened by transcriptome screening, stress data analysis and vitro validation experiments. Results The analysis exhibited 36,144,564 micro-related clean reads and 244,213 unigene. KEGG, eggNOG and CAZy functional annotation analysis indicated that signal transduction and material metabolism were the most important function of xylem sap. DEGs analysis were mainly about disease resistance, carbon source metabolism and hormone signal transduction, especially in P3 vs P1, enriched in the plant-pathogen interaction pathway. Analysis on grape genome information revealed xylem sap had little RNA with weak life activity. Metabolic pathways, biosynthesis of secondary metabolites, plant hormone signal transduction and plant-pathogen interaction were the four pathways with the largest number of enriched genes. Moreover, 16 genes responsive to biotic and abiotic stresses were screened out. Conclusion Promoting plant growth and resisting pathogens were the most important function of xylem sap during the bleeding period, and the function of microbial community were closely related to microorganisms growth and disease resistance. The 16 stress-related genes might be used for the future grape resistance research.