Ghi
Mostrando 13-24 de 40 artigos, teses e dissertações.
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13. Hidrocarbonetos policíclicos aromáticos (HPAs) em aguardentes
A presença de hidrocarbonetos aromáticos polinucleares (HPAs) em aguardentes foi investigada por cromatografia líquida (CLAE) após sua prévia extração em fase sólida (SPE). A separação foi realizada em uma coluna Supelco, LCPAH-octadecil silano (25cm x 4,6mm x 5mm) com gradiente acetonitrila/água e a quantificação utilizando detector de fluoresc
Food Science and Technology. Publicado em: 2005-06
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14. In Vivo and In Vitro Evidence that TtgV Is the Specific Regulator of the TtgGHI Multidrug and Solvent Efflux Pump of Pseudomonas putida
The TtgGHI efflux pump of Pseudomonas putida DOT-T1E plays a key role in the innate and induced tolerance of this strain to aromatic hydrocarbons and antibiotics. The ttgGHI operon is expressed constitutively from two overlapping promoters in the absence of solvents and at a higher level in their presence, but not in response to antibiotics. Adjacent to the
American Society for Microbiology.
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15. TtgV Bound to a Complex Operator Site Represses Transcription of the Promoter for the Multidrug and Solvent Extrusion TtgGHI Pump
The TtgGHI efflux pump of Pseudomonas putida extrudes a variety of antibiotics and solvents. We show that the ttgGHI operon is transcribed in vitro and in vivo from a single promoter and not from two overlapping promoters as previously proposed. The expression of this promoter is controlled by the TtgV repressor, whose operator expands through four helical t
American Society for Microbiology.
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16. Structural Genes for Nitrate-Inducible Formate Dehydrogenase in Escherichia Coli K-12
Formate oxidation coupled to nitrate reduction constitutes a major anaerobic respiratory pathway in Escherichia coli. This respiratory chain consists of formate dehydrogenase-N, quinone, and nitrate reductase. We have isolated a recombinant DNA clone that likely contains the structural genes, fdnGHI, for the three subunits of formate dehydrogenase-N. The fdn
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17. Characterization by electron paramagnetic resonance of the role of the Escherichia coli nitrate reductase (NarGHI) iron-sulfur clusters in electron transfer to nitrate and identification of a semiquinone radical intermediate.
We have used Escherichia coli cytoplasmic membrane preparations enriched in wild-type and mutant (NarH-C16A and NarH-C263A) nitrate reductase (NarGHI) to study the role of the [Fe-S] clusters of this enzyme in electron transfer from quinol to nitrate. The spectrum of dithionite-reduced membrane bound NarGHI has major features comprising peaks at g = 2.04 and
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18. Coordinate Regulation of the Escherichia coli Formate Dehydrogenase fdnGHI and fdhF Genes in Response to Nitrate, Nitrite, and Formate: Roles for NarL and NarP
Escherichia coli possesses three distinct formate dehydrogenase enzymes encoded by the fdnGHI, fdhF, and fdoGHI operons. To examine how two of the formate dehyrogenase operons (fdnGHI and fdhF) are expressed anaerobically in the presence of low, intermediate, and high levels of nitrate, nitrite, and formate, chemostat culture techniques were employed with fd
American Society for Microbiology.
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19. Three Efflux Pumps Are Required To Provide Efficient Tolerance to Toluene in Pseudomonas putida DOT-T1E
In Pseudomonas putida DOT-T1E multidrug efflux pumps of the resistance-nodulation-division family make a major contribution to solvent resistance. Two pumps have been identified: TtgABC, expressed constitutively, and TtgDEF, induced by aromatic hydrocarbons. A double mutant lacking both efflux pumps was able to survive a sudden toluene shock if and only if p
American Society for Microbiology.
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20. Pseudoexon Activation as a Novel Mechanism for Disease Resulting in Atypical Growth-Hormone Insensitivity
Inherited growth-hormone insensitivity (GHI) is a heterogeneous disorder that is often caused by mutations in the coding exons or flanking intronic sequences of the growth-hormone receptor gene (GHR). Here we describe a novel point mutation, in four children with GHI, that leads to activation of an intronic pseudoexon resulting in inclusion of an additional
The American Society of Human Genetics.
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21. Flagella and Chemotaxis Are Required for Efficient Induction of Salmonella enterica Serovar Typhimurium Colitis in Streptomycin-Pretreated Mice
Salmonella enterica subspecies 1 serovar Typhimurium is a common cause of gastrointestinal infections. The host's innate immune system and a complex set of Salmonella virulence factors are thought to contribute to enteric disease. The serovar Typhimurium virulence factors have been studied extensively by using tissue culture assays, and bovine infection mode
American Society for Microbiology.
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22. Genetic evidence that genes fdhD and fdhE do not control synthesis of formate dehydrogenase-N in Escherichia coli K-12.
Enterobacteria synthesize two formate dehydrogenases, formate dehydrogenase-N (encoded by fdnGHI) and formate dehydrogenase H (encoded by fdhF). Previous work has identified two rha-linked Salmonella typhimurium genes, fdnB and fdnC, which are required primarily for formate dehydrogenase-N activity. Analogous mutants, termed fdhD and fdhE, have been isolated
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23. Rhizobium meliloti fixGHI sequence predicts involvement of a specific cation pump in symbiotic nitrogen fixation.
We present genetic and structural analyses of a fix operon conserved among rhizobia, fixGHI from Rhizobium meliloti. The nucleotide sequence of the operon suggests it may contain a fourth gene, fixS. Adjacent open reading frames of this operon showed an overlap between TGA stop codons and ATG start codons in the form of an ATGA motif suggestive of translatio
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24. A protein-dependent riboswitch controlling ptsGHI operon expression in Bacillus subtilis: RNA structure rather than sequence provides interaction specificity
The Gram-positive soil bacterium Bacillus subtilis transports glucose by the phosphotransferase system. The genes for this system are encoded in the ptsGHI operon. The expression of this operon is controlled at the level of transcript elongation by a protein-dependent riboswitch. In the absence of glucose a transcriptional terminator prevents elongation into
Oxford University Press.