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1.
Robin C. Chiang Ricardo Cavicchioli & Robert P. Gunsalus 《Molecular microbiology》1997,24(5):1049-1060
The Escherichia coli NarX, NarQ, NarL and NarP proteins comprise a two-component regulatory system that controls the expression of many anaerobic electron-transport and fermentation-related genes in response to nitrate and nitrite. Either of the two sensor-transmitter proteins, NarX and NarQ, can activate the response-regulator proteins, NarL and NarP, which in turn are able to bind at their respective DNA regulatory sites to modulate gene expression. NarX contains a conserved 17 amino acid sequence, designated the ‘P-box’ element, that is essential for nitrate sensing. In this study we characterize narQ mutants that also confer altered nitrate control of NarL-dependent nitrate reductase (narGHJI ) and fumarate reductase (frdABCD) gene expression. While some narQ mutations cause the constitutive activation or repression of reporter-gene expression even when the cells are grown in the absence of the nitrate signal (i.e. a ‘locked-on’ phenotype), other mutations abolish nitrate-dependent control (i.e. a ‘locked-off’ phenotype). Interestingly the narQ (A42→T) and narQ (R50→Q) mutations along with the analogous narX18 (A46→T) and narX902 (R54→E) mutations also confer a ‘locked-on’ or a ‘locked-off’ phenotype in response to nitrite, the second environmental signal detected by NarQ and NarX. Furthermore, these narQ and narX mutations also affect NarP-dependent gene regulation of nitrite reductase (nrfABCDEFG) and aeg-46.5 gene expression in response to nitrite. We therefore propose that the NarQ sensor-transmitter protein also detects nitrate and nitrite in the periplasmic space via its periplasmic domain. A signal transduction model, which we previously proposed for NarX, is now extended to NarQ, in which a nitrate- or nitrite-detection event in the periplasmic region of the cell is followed by a signal transduction event through the inner membrane to the cytoplasmic domain of NarQ and NarX proteins to modulate their protein kinase/phosphatase activities. 相似文献
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Zizhen Yao Cindy T.J. van Velthoven Thuc Nghi Nguyen Jeff Goldy Adriana E. Sedeno-Cortes Fahimeh Baftizadeh Darren Bertagnolli Tamara Casper Megan Chiang Kirsten Crichton Song-Lin Ding Olivia Fong Emma Garren Alexandra Glandon Nathan W. Gouwens James Gray Lucas T. Graybuck Michael J. Hawrylycz Hongkui Zeng 《Cell》2021,184(12):3222-3241.e26
4.
L.C. Chiang H.Y. Hsiao M.C. Flickinger L.F. Chen G.T. Tsao 《Enzyme and microbial technology》1982,4(2):93-95
The capabilities of immobilized Fusarium oxysporum f. sp. lini, Mucor sp., and Saccharomyces cerevisiae in fermenting pentose to ethanol have been compared. S. cerevisiae was found to have the best fermentation rate on d-xylulose of 0.3 g l?1 h?1. By using a separate isomerase column for converting d-xylose to d-xylulose and a yeast column for converting d-xylulose to ethanol, an ethanol concentration of 32 g l?1 was obtained from 10% d-xylose. The ethanol yield was calculated to be 64% of the theoretical yield. 相似文献
5.
The axial structures, the notochord and the neural tube, play an essential role in the dorsoventral patterning of somites and in the differentiation of their many cell lineages. Here, we investigated the role of the axial structures in the mediolateral patterning of the somite by using a newly identified murine homeobox gene, Nkx-3.1, as a medial somitic marker in explant in vitro assays. Nkx-3.1 is dynamically expressed during somitogenesis only in the youngest, most newly-formed somites at the caudal end of the embryo. We found that the expression of Nkx-3.1 in pre-somitic tissue explants is induced by the notochord and maintained in newly-differentiated somites by the notochord and both ventral and dorsal parts of the neural tube. We showed that Sonic hedgehog (Shh) is one of the signaling molecules that can reproduce the effect of the axial structures by exposing explants to either COS cells transfected with a Shh expression construct or to recombinant SHH. Shh could induce and maintain Nkx-3.1 expression in pre-somitic mesoderm and young somites but not in more mature, differentiated ones. The effects of Shh on Nkx-3.1 expression were antagonized by a forskolin-induced increase in the activity of cyclic AMP-dependent protein kinase A. Additionally, we confirmed that the expression of the earliest expressed murine myogenic marker, myf 5, is also regulated by the axial strucutres but that Shh by itself is not capable of inducing or maintaining it. We suggest that the establishment of somitic medial and lateral compartments and the early events in myogenesis are governed by a combination of positive and inhibitory signals derived from the neighboring structures, as has previously been proposed for the dorsoventral patterning of somites. 相似文献
6.
Rong Chen Alex A Morgan Joel Dudley Tarangini Deshpande Li Li Keiichi Kodama Annie P Chiang Atul J Butte 《Genome biology》2009,9(12):R170
Background
Candidate single nucleotide polymorphisms (SNPs) from genome-wide association studies (GWASs) were often selected for validation based on their functional annotation, which was inadequate and biased. We propose to use the more than 200,000 microarray studies in the Gene Expression Omnibus to systematically prioritize candidate SNPs from GWASs. 相似文献7.
8.
Background
Eosinophilia plays the major role in the pathogenesis of asthma and correlates with the up‐regulation of eotaxin, which, together with interleukin (IL)‐5, is important for differentiation, chemo‐attraction, degranulation, and survival of eosinophils in local tissue. In a previous study, we found that administration of lentivirus‐delivered short hairpin RNA (shRNA) to suppress the expression of IL‐5 inhibited airway inflammation. The present study aimed to investigate the role of eotaxin shRNA and the synergistic effect of eotaxin and IL‐5 shRNAs on airway inflammation in an ovalbumin (OVA)‐induced murine model of asthma.Methods
Lentivirus‐delivered shRNAs were used to suppress the expression of eotaxin and/or IL‐5 in local tissue in an OVA‐induced murine asthma model.Results
Intra‐tracheal administration of lentivirus containing eotaxin shRNA expressing cassette (eoSEC3.3) efficiently moderated the characteristics of asthma, including airway hyper‐responsiveness, cellular infiltration of lung tissues, and eotaxin and IL‐5 levels in bronchio‐alveolar lavage fluid. Administration of lentiviruses expressing IL‐5 or eotaxin shRNAs (IL5SEC4 + eoSEC3.3) also moderated the symptoms of asthma in a mouse model.Conclusions
Local delivery of lentiviruses expressing IL‐5 and eotaxin shRNAs provides a potential tool in moderating airway inflammation and also has the potential for developing clinical therapy based on the application of shRNAs of chemokines and cytokines involved in T helper 2 cell inflammation and eosinophilia. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献9.
Chun Chiang 《Biological cybernetics》1980,36(3):131-135
The human system of pattern recognition is explored. This system utilizes the method of syntactic feature comparison, activation of the patterns containing the feature, and sorting among the activated patterns. Both the pattern recognition process without thinking and with thinking are discussed, and examples are given. Contrary to the usual concept, the more complicated pattern has a better chance to be recognized correctly.A portion of this paper has been presented at the 1977 International Cybernetic Conference in Washington 相似文献
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