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871.
872.
Jake Whang Jungoh Ahn Chang-Soo Chun Yeo-Jin Son Hongweon Lee Eui-Sung Choi 《Process Biochemistry》2009,44(10):1190-1192
An efficient yeast gene expression system with GAL10 promoter that does not require galactose as an inducer was developed using Δgal80 mutant strain of Saccharomyces cerevisiae. We constructed several combinations of gal mutations (Δgal1, Δgal80, Δmig1, Δmig2, and Δgal6) of S. cerevisiae and tested for their effect on efficiency of recombinant protein production by GAL10 promoter using a lipase, Candida antarctica lipase B (CalB), as a reporter. While the use of Δgal1 mutant strain required the addition of a certain amount of galactose to the medium, Δgal80 mutant strain did not require galactose. Furthermore, it was found that the recombinant CalB could be produced more efficiently (1.6-fold at 5 L-scale fermentation) in Δgal80 mutant strain than in the Δgal1 mutant. The Δgal80 mutant strain showed glucose repressible mode of expression of GAL10 promoter. Using Δgal80 mutant strain of S. cerevisiae, CalB was efficiently produced in a glucose-only fermentation at volumes up to 500 L. 相似文献
873.
874.
875.
Minke E. Binnerts Nenad Tomasevic Jessica M. Bright John Leung Victoria E. Ahn Kyung-Ah Kim Xiaoming Zhan Shouchun Liu Shirlee Yonkovich Jason Williams Mei Zhou Delphine Gros Melissa Dixon Wouter Korver William I. Weis Arie Abo 《Molecular biology of the cell》2009,20(15):3552-3560
The Wnt coreceptor LRP6 is required for canonical Wnt signaling. To understand the molecular regulation of LRP6 function, we generated a series of monoclonal antibodies against the extra cellular domain (ECD) of LRP6 and selected a high-affinity mAb (mAb135) that recognizes cell surface expression of endogenous LRP6. mAb135 enhanced Wnt dependent TCF reporter activation and antagonized DKK1 dependent inhibition of Wnt3A signaling, suggesting a role in modulation of LRP6 function. Detailed analysis of LRP6 domain mutants identified Ser 243 in the first propeller domain of LRP6 as a critical residue for mAb135 binding, implicating this domain in regulating the sensitivity of LRP6 to DKK1. In agreement with this notion, mAb135 directly disrupted the interaction of DKK1 with recombinant ECD LRP6 and a truncated form of the LRP6 ECD containing only repeats 1 and 2. Finally, we found that mAb135 completely protected LRP6 from DKK1 dependent internalization. Together, these results identify the first propeller domain as a novel regulatory domain for DKK1 binding to LRP6 and show that mAb against the first propeller domain of LRP6 can be used to modulate this interaction. 相似文献
876.
This study investigated the contribution of microfiltration to phosphorus removal in the sequencing anoxic/anaerobic membrane
bioreactor. The phosphorus content in activated sludge was fractionated by the Schmidt–Thannhauser–Schneider method. The size
distribution of phosphorus in the influent was analyzed to estimate the portion of particulate phosphorus rejected physically
by the 0.2 μm microfiltration. The result was that along with the high removal of phosphorus (83%) the phosphorus content
of activated sludge was measured as 58.66 mgP/gVSS corresponding to 5.87% on dry weight basis. About 9% of total phosphorus
was chemically precipitated phosphates while 56% was stored inside the microbial cell by activity of PAOs, and 35% was the
sum of minor intracellular compositions and the particulate residuals, which could be rejected completely by the microfiltration.
The biological activity is the dominant way of phosphorus removal in the process. However, the microfiltration also contributed
significantly to phosphorus removal by retaining the particulate phosphorus inside the system. 相似文献
877.
Byoung Chan Kim Daniel Lopez‐Ferrer Sang‐Mok Lee Hye‐Kyung Ahn Sujith Nair Seong H. Kim Beom Soo Kim Konstantinos Petritis David G. Camp Jay W. Grate Richard D. Smith Yoon‐Mo Koo Man Bock Gu Professor Jungbae Kim Professor 《Proteomics》2009,9(7):1893-1900
A stable and robust trypsin‐based biocatalytic system was developed and demonstrated for proteomic applications. The system utilizes polymer nanofibers coated with trypsin aggregates for immobilized protease digestions. After covalently attaching an initial layer of trypsin to the polymer nanofibers, highly concentrated trypsin molecules are crosslinked to the layered trypsin by way of a glutaraldehyde treatment. This process produced a 300‐fold increase in trypsin activity compared with a conventional method for covalent trypsin immobilization, and proved to be robust in that it still maintained a high level of activity after a year of repeated recycling. This highly stable form of immobilized trypsin was resistant to autolysis, enabling repeated digestions of BSA over 40 days and successful peptide identification by LC‐MS/MS. This active and stable form of immobilized trypsin was successfully employed in the digestion of yeast proteome extract with high reproducibility and within shorter time than conventional protein digestion using solution phase trypsin. Finally, the immobilized trypsin was resistant to proteolysis when exposed to other enzymes (i.e., chymotrypsin), which makes it suitable for use in “real‐world” proteomic applications. Overall, the biocatalytic nanofibers with trypsin aggregate coatings proved to be an effective approach for repeated and automated protein digestion in proteomic analyses. 相似文献
878.
Dong-Soo Park Soo-Kwon Park Sang-Ik Han Hoe-Jeong Wang Nam-Soo Jun Norvie L. Manigbas Young-Min Woo Byoung-Ohg Ahn Doh-Won Yun Ung-Han Yoon Yong-Hwan Kim Myung-Chul Lee Doh-Hoon Kim Min-Hee Nam Chang-Deok Han Hang-Won Kang Gihwan Yi 《Molecular breeding : new strategies in plant improvement》2009,24(1):1-15
A gene detection strategy using two-component Ac/Ds construct, with the mobile Ds transposon, has been developed to better understand gene functions in crops. Currently, 115,000 Ds insertion lines have been generated through the Ac/Ds gene trap system in Korea using japonica rice Dongjin as donor. Four hundred and thirty-seven mutants from 12,162 Ds-tagged lines were catalogued, including physiological and agronomic traits. Different traits were identified with distinct
characteristics in terms of tillers, panicles, leaves, flowers, seed, chlorophyll content, and height. Culm and panicle length,
number of panicles, and days to flowering of the Dongjin Ds population revealed high standard deviations compared with the donor cultivar. An evaluation of the Ds distribution on the chromosome revealed that 74.5% of the Ds were reinserted into gene-rich regions, making this Ac/Ds-mediated gene trap system useful in helping to gain an understanding of the function of genes and thus improve the gene-tagging
system in rice. 相似文献
879.
Biomass granulation in an aerobic:anaerobic-enhanced biological phosphorus removal process in a sequencing batch reactor with varying pH 总被引:1,自引:0,他引:1
Johwan Ahn Simon McIlroy Sarah Schroeder Robert Seviour 《Journal of industrial microbiology & biotechnology》2009,36(7):885-893
Long-term influences of different steady-state pH conditions on microbial community composition were determined by fluorescence
in situ hybridization (FISH) in a laboratory scale reactor configured for enhanced biological phosphorus removal (EBPR). Chemical
profiles were consistent with shifts in populations from polyphosphate-accumulating organisms (PAO) to glycogen-accumulating
organisms (GAO) when pH fell from pH 7.5 to 7.0 and then to 6.5. While biomass was both dispersed and flocculated at pH 7.5,
almost complete granulation occurred gradually after pH was dropped to 7.0, and these granules increased in size as the pH
was reduced further to 6.5. Reverting back to pH 7.5 led to granule breakdown and corresponding increases in anaerobic phosphate
release. Granules consisted almost entirely of Accumulibacter PAO cells, while putative GAO populations were always present in small numbers. Results suggest that low pH may contribute
to granulation under these operational conditions. While chemical profiles suggested the PAO:GAO balance was changing as pH
fell, FISH failed to reveal any marked corresponding increase in GAO abundances. Instead, TEM evidence suggested the Accumulibacter PAO phenotype was becoming more like that of a GAO. These data show how metabolically adaptable the Accumulibacter PAO can be under anaerobic:aerobic conditions in being able to cope with marked changes in plant conditions. They suggest
that decreases in EBPR capacity may not necessarily reflect shifts in community composition, but in the existing population
metabolism. 相似文献
880.
Jeong-Eun Kim Dong-Joo You Cheolju Lee Curie Ahn Jae Young Seong Jong-Ik Hwang 《Cellular signalling》2010,22(11):1645-1654
IκB kinase β (IKKβ) plays a crucial role in biological processes, including immune response, stress response, and tumor development by mediating the activation of various signaling molecules such as NF-κB. Extensive studies on the mechanisms underlying IKK activation have led to the identification of new activators and have facilitated an understanding of the cellular responses related to NF-κB and other target molecules. However, the molecular processes that modulate IKK activity are still unknown. In this study, we show that KEAP1 is a new IKK binding partner, which is responsible for the down-regulation of TNFα-stimulated NF-κB activation. The E(T/S)GE motif, which is found only in the IKKβ subunit of the IKK complex, is essential for interaction with the C-terminal Kelch domain of KEAP1. Reduction of KEAP1 expression by small interfering RNA enhanced NF-κB activity, and up-regulated the expression of NF-κB target genes. Ectopic expression of KEAP1 decreased the expression of IKKβ, which was restored by an autophagy inhibitor. IKK phosphorylation stimulated by TNFα was blocked by KEAP1. Our data demonstrate that KEAP1 is involved in the negative regulation of NF-κB signaling through the inhibition of IKKβ phosphorylation and the mediation of autophagy-dependent IKKβ degradation. 相似文献