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241.
It has been reported that flashing light enhances microalgal biomass productivity and overall photosynthetic efficiency. The
algal growth kinetics and oxygen production rates under flashing light with various flashing frequencies (5 Hz-37 kHz) were
compared with those under equivalent continuous light in photobioreactors. A positive flashing light effect was observed with
flashing frequencies over 1 kHz. The oxygen production rate under conditions of flashing light was slightly higher than that
under continuous light. The cells under the high frequency flashing light were also observed to be healthier than those under
continuous light, particularly at higher cell concentrations. When 37 kHz flashing light was applied to an LED-based photobioreactor,
the cell concentration was higher than that obtained under continuous light by about 20%. Flashing light may be a reasonable
solution to overcome mutual shading, particularly in high-density algal cultures. 相似文献
242.
Lee JW Gwak KS Kim SI Kim M Choi DH Choi IG 《Journal of microbiology and biotechnology》2007,17(11):1811-1817
Extracellular enzymes from Lentinus edodes M290 on normal woods (Quercus mongolica) and waste logs from oak mushroom production were comparatively investigated. Endoglucanase, cellobiohydrolase, beta-glucosidase, and xylanase activities were higher on waste mushroom logs than on normal woods after L. edodes M290 inoculation. Xylanase activity was especially different, with a three times higher activity on waste mushroom logs. When the waste mushroom logs were used as a carbon source, a new 35 kDa protein appeared. After the purification, the optimal pH and temperature for xylanase activity were determined to be 4.0 and 50 degrees C, respectively. More than 50% of the optimal xylanase activity was retained when the temperature was increased from 20 to 60 degrees C, after a 240 min reaction. At 40 degrees C, the xylanase maintained 93% of the optimal activity, after a 240 min reaction. The purified xylanase showed a very high homology to the xylanase family 10 from Aspergillus terreus by LC/MS-MS analysis. The highest Xcorr (1.737) was obtained from the peptide KWI SQGIPIDGIG SQTHLGSGGS WTVK originated from Aspergillus terreus, indicating that the 35 kDa protein was xylanase. This protein showed low homology to a previously reported L. edodes xylanase sequence. 相似文献
243.
244.
Lee CH 《Applied microbiology and biotechnology》2012,93(2):517-523
One of the primary limitations of cancer therapy is lack of selectivity of therapeutic agents to tumor cells. Current efforts
are focused on discovering and developing anticancer agents that selectively target only tumor cells and spare normal cells
to improve the therapeutic index. The use of preferentially replicating bacteria as an oncolytic agent is one of the innovative
approaches for the treatment of cancer. This is based on the observation that some obligate or facultative anaerobic bacteria
are capable of multiplying selectively in tumors and inhibiting their growth. Meanwhile, bacteria have been demonstrated to
colonize and destroy tumor, and have emerged as biological gene vectors to tumor microenvironment. To improve the efficacy
and safety of the bacterial therapy, a further understanding of bacteria between with immune system is required. Furthermore,
we want to evaluate how bacterial infection facilitates the “bystander effect” of chemotherapeutic agent and assess if it
can be used for additional antitumor effect when combined with chemotherapy. This study may not only evaluate therapeutic
efficacy of bacteria for the treatment of cancer but also elucidate the mechanisms underlying antitumor activities mediated
by bacteria, which involve host immune responses and the cellular molecular responses. 相似文献
245.
Jang do S Lee HJ Lee B Hong BH Cha HJ Yoon J Lim K Yoon YJ Kim J Ree M Lee HC Choi KY 《FEBS letters》2006,580(17):4166-4171
Failure to detect the intermediate in spite of its existence often leads to the conclusion that two-state transition in the unfolding process of the protein can be justified. In contrast to the previous equilibrium unfolding experiment fitted to a two-state model by circular dichroism and fluorescence spectroscopies, an equilibrium unfolding intermediate of a dimeric ketosteroid isomerase (KSI) could be detected by small angle X-ray scattering (SAXS) and analytical ultracentrifugation. The sizes of KSI were determined to be 18.7A in 0M urea, 17.3A in 5.2M urea, and 25.1A in 7M urea by SAXS. The size of KSI in 5.2M urea was significantly decreased compared with those in 0M and 7M urea, suggesting the existence of a compact intermediate. Sedimentation velocity as obtained by ultracentrifugation confirmed that KSI in 5.2M urea is distinctly different from native and fully-unfolded forms. The sizes measured by pulse field gradient nuclear magnetic resonance (NMR) spectroscopy were consistent with those obtained by SAXS. Discrepancy of equilibrium unfolding studies between size measurement methods and optical spectroscopies might be due to the failure in detecting the intermediate by optical spectroscopic methods. Further characterization of the intermediate using (1)H NMR spectroscopy and Kratky plot supported the existence of a partially-folded form of KSI which is distinct from those of native and fully-unfolded KSIs. Taken together, our results suggest that the formation of a compact intermediate should precede the association of monomers prior to the dimerization process during the folding of KSI. 相似文献
246.
247.
Peter J. M. van den Elzen Jeffrey Townsend Kathleen Y. Lee John R. Bedbrook 《Plant molecular biology》1985,5(5):299-302
Summary We show here that plant cells are sensitive to the antibiotic hygromycin-B4. We also show that a chimaeric gene consisting of the nopaline synthase (nos) gene regulatory elements and the E. coli derived hygromycin phosphotransferase (hpt) gene, when transferred to plants' cells, confers resistance to hygromycin B. The chimaeric nos-hpt gene enables efficient selection of DNA transfer to plant cells when used in conjunction with Ti plasmid-derived binary vectors in cocultivation experiments. 相似文献
248.
Lee JC Won SJ Chao CL Wu FL Liu HS Ling P Lin CN Su CL 《Biochemical and biophysical research communications》2008,372(1):236-242
Morusin is a pure compound isolated from root bark of Morusaustralis (Moraceae). In this study, we demonstrated that morusin significantly inhibited the growth and clonogenicity of human colorectal cancer HT-29 cells. Apoptosis induced by morusin was characterized by accumulation of cells at the sub-G1 phase, fragmentation of DNA, and condensation of chromatin. Morusin also inhibited the phosphorylation of IKK-α, IKK-β and IκB-α, increased expression of IκB-α, and suppressed nuclear translocation of NF-κB and its DNA binding activity. Dephosphorylation of NF-κB upstream regulators PI3K, Akt and PDK1 was also displayed. In addition, activation of caspase-8, change of mitochondrial membrane potential, release of cytochrome c and Smac/DIABLO, and activation of caspase-9 and -3 were observed at the early time point. Downregulation in the expression of Ku70 and XIAP was exhibited afterward. Caspase-8 or wide-ranging caspase inhibitor suppressed morusin-induced apoptosis. Therefore, the antitumor mechanism of morusin in HT-29 cells may be via activation of caspases and inhibition of NF-κB. 相似文献
249.
250.
Liu J Ernst SA Gladycheva SE Lee YY Lentz SI Ho CS Li Q Stuenkel EL 《The Journal of biological chemistry》2004,279(53):55924-55936
Syntaxin1A, a neural-specific N-ethylmaleimide-sensitive factor attachment protein receptor protein essential to neurotransmitter release, in isolation forms a closed conformation with an N-terminal alpha-helix bundle folded upon the SNARE motif (H3 domain), thereby limiting interaction of the H3 domain with cognate SNAREs. Munc18-1, a neural-specific member of the Sec1/Munc18 protein family, binds to syntaxin1A, stabilizing this closed conformation. We used fluorescence resonance energy transfer (FRET) to characterize the Munc18-1/syntaxin1A interaction in intact cells. Enhanced cyan fluorescent protein-Munc18-1 and a citrine variant of enhanced yellow fluorescent protein-syntaxin1A, or mutants of these proteins, were expressed as donor and acceptor pairs in human embryonic kidney HEK293-S3 and adrenal chromaffin cells. Apparent FRET efficiency was measured using two independent approaches with complementary results that unambiguously verified FRET and provided a spatial map of FRET efficiency. In addition, enhanced cyan fluorescent protein-Munc18-1 and a citrine variant of enhanced yellow fluorescent protein-syntaxin1A colocalized with a Golgi marker and exhibited FRET at early expression times, whereas a strong plasma membrane colocalization, with similar FRET values, was apparent at later times. Trafficking of syntaxin1A to the plasma membrane was dependent on the presence of Munc18-1. Both syntaxin1A(L165A/E166A), a constitutively open conformation mutant, and syntaxin1A(I233A), an H3 domain point mutant, demonstrated apparent FRET efficiency that was reduced approximately 70% from control. In contrast, the H3 domain mutant syntaxin1A(I209A) had no effect. By using phosphomimetic mutants of Munc18-1, we also established that Ser-313, a Munc18-1 protein kinase C phosphorylation site, and Thr-574, a cyclin-dependent kinase 5 phosphorylation site, regulate Munc18-1/syntaxin1A interaction in HEK293-S3 and chromaffin cells. We conclude that FRET imaging in living cells may allow correlated regulation of Munc18-1/syntaxin1A interactions to Ca(2+)-regulated secretory events. 相似文献