In microbial fuel cell (MFC), the rate of electron transfer to anode electrode is a key intrinsic limiting factor on the power output of MFCs. Using Klebsiella pneumoniae (K. pneumoniae) strain L17 as biocatalyst, we ...In microbial fuel cell (MFC), the rate of electron transfer to anode electrode is a key intrinsic limiting factor on the power output of MFCs. Using Klebsiella pneumoniae (K. pneumoniae) strain L17 as biocatalyst, we studied the mechanism of electron shuttle via self-producing mediator in a cubic air-chamber MFC. To eliminate the influence of biofilm mechanism, the anode electrode was coated with microfiltration membrane (0.22 μm). Data showed that the microfiltration membrane coated and uncoated MFCs achieved the maximum voltage outputs of 316.2 and 426.2 mV after 270 and 120 h, respectively. When the medium was replaced in MFCs that had the highest power generation, the power output dropped by 62.1% and 8.8%, and required 120 and 48 h to resume the original level in the coated and uncoated MFCs, respectively. The results suggested an electron-shuttle mechanism rather than biofilm mechanism was responsible for electricity generation in the membrane coated MFC. Cyclic voltammetric measurements demonstrated the presence of an electrochemical active compound produced by K. pneumoniae strain L17, which was identified to be 2,6-di-tert-butyl-p-benzoquinon (2,6-DTBBQ) by GC-MS. 2,6-DTBBQ, as a recyclable electron shuttle, could transfer electrons between K. pneumoniae L17 and the anode electrode.展开更多
P68 RNA helicase is a prototypical DEAD box RNA helicase. The protein plays a very important role in early organ development and maturation. Consistent with the function of the protein in transcriptional regulation an...P68 RNA helicase is a prototypical DEAD box RNA helicase. The protein plays a very important role in early organ development and maturation. Consistent with the function of the protein in transcriptional regulation and pre-mRNA splicing, p68 was found to predominately localize in the cell nucleus. However, recent experiments demon- strate a transient cytoplasmic localization of the protein. We report here that p68 shuttles between the nucleus and the cytoplasm. The nucleocytoplasmic shuttling of p68 is mediated by two nuclear localization signal and two nuclear exporting signal sequence elements. Our experiments reveal that p68 shuttles via a classical RanGTPase-dependent pathway.展开更多
基金supported by the National Natural Science Foundation of China (No 20777013)Natural Science Foundation of Guangdong Province, China (No 07006759)The Sci & Tech Innovation project of Guangdong Academy of Sciences, China (Gtard No CX200704)
文摘In microbial fuel cell (MFC), the rate of electron transfer to anode electrode is a key intrinsic limiting factor on the power output of MFCs. Using Klebsiella pneumoniae (K. pneumoniae) strain L17 as biocatalyst, we studied the mechanism of electron shuttle via self-producing mediator in a cubic air-chamber MFC. To eliminate the influence of biofilm mechanism, the anode electrode was coated with microfiltration membrane (0.22 μm). Data showed that the microfiltration membrane coated and uncoated MFCs achieved the maximum voltage outputs of 316.2 and 426.2 mV after 270 and 120 h, respectively. When the medium was replaced in MFCs that had the highest power generation, the power output dropped by 62.1% and 8.8%, and required 120 and 48 h to resume the original level in the coated and uncoated MFCs, respectively. The results suggested an electron-shuttle mechanism rather than biofilm mechanism was responsible for electricity generation in the membrane coated MFC. Cyclic voltammetric measurements demonstrated the presence of an electrochemical active compound produced by K. pneumoniae strain L17, which was identified to be 2,6-di-tert-butyl-p-benzoquinon (2,6-DTBBQ) by GC-MS. 2,6-DTBBQ, as a recyclable electron shuttle, could transfer electrons between K. pneumoniae L17 and the anode electrode.
文摘P68 RNA helicase is a prototypical DEAD box RNA helicase. The protein plays a very important role in early organ development and maturation. Consistent with the function of the protein in transcriptional regulation and pre-mRNA splicing, p68 was found to predominately localize in the cell nucleus. However, recent experiments demon- strate a transient cytoplasmic localization of the protein. We report here that p68 shuttles between the nucleus and the cytoplasm. The nucleocytoplasmic shuttling of p68 is mediated by two nuclear localization signal and two nuclear exporting signal sequence elements. Our experiments reveal that p68 shuttles via a classical RanGTPase-dependent pathway.
