• 제목/요약/키워드: school laboratory

검색결과 7,477건 처리시간 0.037초

Removal of Chromium (VI) by Escherichia coli Cells Expressing Cytoplasmic or Surface-Displayed ChrB: a Comparative Study

  • Zhou, Xiaofeng;Li, Jianghui;Wang, Weilong;Yang, Fan;Fan, Bingqian;Zhang, Chenlu;Ren, Xiaojun;Liang, Feng;Cheng, Rong;Jiang, Fengying;Zhou, Huaibin;Yang, Juanjuan;Tan, Guoqiang;Lyu, Jianxin;Wang, Wu
    • Journal of Microbiology and Biotechnology
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    • 제30권7호
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    • pp.996-1004
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    • 2020
  • Various genetically engineered microorganisms have been developed for the removal of heavy metal contaminants. Metal biosorption by whole-cell biosorbents can be enhanced by overproduction of metal-binding proteins/peptides in the cytoplasm or on the cell surface. However, few studies have compared the biosorption capacity of whole cells expressing intracellular or surface-displayed metal-adsorbing proteins. In this study, several constructs were prepared for expressing intracellular and surface-displayed Ochrobactrum tritici 5bvl1 ChrB in Escherichia coli BL21(DE3) cells. E. coli cells expressing surface-displayed ChrB removed more Cr(VI) from aqueous solutions than cells with cytoplasmic ChrB under the same conditions. However, intracellular ChrB was less susceptible to variation in extracellular conditions (pH and ionic strength), and more effectively removed Cr(VI) from industrial wastewater than the surface-displayed ChrB at low pH (<3). An adsorption-desorption experiment demonstrated that compared with intracellular accumulation, cell-surface adsorption is reversible, which allows easy desorption of the adsorbed metal ions and regeneration of the bioadsorbent. In addition, an intrinsic ChrB protein fluorescence assay suggested that pH and salinity may influence the Cr(VI) adsorption capacity of ChrB-expressing E. coli cells by modulating the ChrB protein conformation. Although the characteristics of ChrB may not be universal for all metal-binding proteins, our study provides new insights into different engineering strategies for whole-cell biosorbents for removing heavy metals from industrial effluents.

Codon Optimization, Soluble Expression and Purification of PE_PGRS45 Gene from Mycobacterium tuberculosis and Preparation of Its Polyclonal Antibody Protein

  • Xu, Tao;Li, Minying;Wang, Chutong;Yuan, Meili;Chang, Xianyou;Qian, Zhongqing;Li, Baiqing;Sun, Meiqun;Wang, Hongtao
    • Journal of Microbiology and Biotechnology
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    • 제31권11호
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    • pp.1583-1590
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    • 2021
  • Studies have demonstrated that PE_PGRS45 is constitutively expressed under various environmental conditions (such as nutrient depletion, hypoxia, and low pH) of the in vitro growth conditions examined, indicating that PE_PGRS45 protein is critical to the basic functions of Mycobacterium tuberculosis. However, there are few reports about the biochemical function and pathogenic mechanism of PE_PGRS45 protein. The fact that this M. tuberculosis gene is not easily expressed in E. coli may be mainly due to the high content of G+C and the use of unique codons. Fusion tags are indispensable tools used to improve the soluble expression of recombinant proteins and accelerate the characterization of protein structure and function. In the present study, His6, Trx, and His6-MBP were used as fusion tags, but only MBP-PE_PGRS45 was expressed solubly. The purification using His6-MBP tag-specific binding to the Ni column was easy to separate after the tag cleavage. We used the purified PE_PGRS45 to immunize New Zealand rabbits and obtained anti-PE_PGRS45 serum. We found that the titer of polyclonal antibodies against PE_PGR45 was higher than 1:256000. The result shows that purified PE_PGRS45 can induce New Zealand rabbits to produce high-titer antibodies. In conclusion, the recombinant protein PE_PGRS45 was successfully expressed in E. coli and specific antiserum was prepared, which will be followed by further evaluation of these specific antigens to develop highly sensitive and specific diagnostic tests for tuberculosis.

Factors Potentially Associated with Chemotherapy-induced Anemia in Patients with Solid Cancers

  • Cheng, Ke;Zhao, Feng;Gao, Feng;Dong, Hang;Men, Hai-Tao;Chen, Ye;Li, Long-Hao;Ge, Jun;Tang, Jie;Ding, Jing;Chen, Xin;Du, Yang;Luo, Wu-Xia;Liu, Ji-Yan
    • Asian Pacific Journal of Cancer Prevention
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    • 제13권10호
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    • pp.5057-5061
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    • 2012
  • Purpose: Chemotherapy-induced anemia (CIA) is one of the most important causes of anemia in cancer patients. This study was conducted to describe the prevalence and characteristics of CIA in solid cancer patients in the Chinese population, and to explore the relationship of white blood cell (WBC) or platelet decrease with CIA. Methods: Data on age, gender, tumor diagnosis, anti-cancer treatment and blood cell analyses were available from 220 untreated non-anemic cancer patients who received at least 2 cycles of chemotherapy, and the data were analyzed to assess their relationship with CIA or its severity. Results: 139 patients (63.2%) presented anemia, most being Grade 1 or 2. Esophageal and lung cancers were associated with a high prevalence. G3/4 leucopenia and decrease of platelets were identified as independent risk factors for the occurrence of CIA. Moreover, G3/4 leucopenia, decrease of platelet and G3/4 thrombocytopenia were found to be also associated with the severity of CIA. Cisplatin-containing regimens were a main potential factor in causing CIA, although significant association was only found on univariate analysis. Conclusion: Anemia or decrease in hematoglobin are common in Chinese cancer patients receiving chemotherapy. Cisplatin-containing regimens might be an important factor influencing the occurrence of CIA. Our analysis firstly described some risk factors, such as decrease of platelets or WBCs, severity of leucopenia or thrombocytopenia, associated with the occurrence and severity of CIA.