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11.
LM Harris L Blank RP Desai NE Welker ET Papoutsakis 《Journal of industrial microbiology & biotechnology》2001,27(5):322-328
The effect of solR inactivation on the metabolism of Clostridium acetobutylicum was examined using fermentation characterization and metabolic flux analysis. The solR-inactivated strain (SolRH) of this study had a higher rate of glucose utilization and produced higher solvent concentrations
(by 25%, 14%, and 81%, respectively, for butanol, acetone, and ethanol) compared to the wild type. Strain SolRH(pTAAD), carrying
a plasmid-encoded copy of the bifunctional alcohol/aldehyde dehydrogenase gene (aad) used in butanol production, produced even higher concentrations of solvents (by 21%, 45%, and 62%, respectively, for butanol,
acetone, and ethanol) than strain SolRH. Clarithromycin used for strain SolRH maintenance during SolRH(pTAAD) fermentations
did not alter product formation; however, tetracycline used for pTAAD maintenance resulted in 90% lower solvent production.
Journal of Industrial Microbiology & Biotechnology (2001) 27, 322–328.
Received 12 September 2000/ Accepted in revised form 21 July 2001 相似文献
12.
Japanese quail eggs were injected with 1-(2-chlorophenyl)-1-(4-chlorophenyl)-2,2,2-trichloroethane o,p'-DDT(1-10 mg),1,1-bis(4-chlorophenyl)-2,2,2-trichloroethane p,p'-DDT (1-10 mg), or, in one study, 0.5 mg chlordecone dissolved in 50 microliters of corn oil on day 1 of incubation. Hatchability was not decreased by o,p'-DDT or p,p'-DDT, as compared to corn-oil-injected controls, but was reduced in progeny of parents injected in ovo with either isomer. Tremor was observed for up to 4 days posthatching only in birds injected with 1.75-10 mg p,p'-DDT or chlordecone. Survivability to 5 weeks posthatch was reduced (less than or equal to 50%) in birds injected in ovo with 6.25-7.5 mg, o,p'-DDT or 1.75-5 mg p,p'-DDT as compared to corn oil (96%). Reproductive behaviors were attenuated in birds injected during development with o,p'-DDT, both DDT isomers decreased the total number of ovipositions, and o,p'-DDT increased the total number of eggshell malformations. Neither body weights nor reproductive organ weights at 12 weeks were affected by injection of either isomer. Exposure to DDT did not affect acquisition of a matched-to-sample food-reinforced response or subsequent responding on a random interval schedule of reinforcement. In another experiment, total circulating erythrocyte numbers were reduced in females after injection in ovo with o,p'-DDT but not after injection with p,p'-DDT. A primary humoral immune response was not affected by in ovo exposure to either isomer of DDT. In ovo exposure to o,p'-DDT but not to p,p'-DDT had long-term and estrogen-like effects on behavior and hematology in Japanese quail. Posthatch primary feather morphology was also altered by embryonic exposure to o,p'-DDT, p,p'-DDT, and chlordecone. 相似文献
13.
Emma L Hesketh John RP Knight Rosemary HC Wilson James PJ Chong Dawn Coverley 《Cell cycle (Georgetown, Tex.)》2015,14(3):333-341
The minichromosome maintenance complex (MCM2-7) is the putative DNA helicase in
eukaryotes, and essential for DNA replication. By applying serial extractions to mammalian
cells synchronized by release from quiescence, we reveal dynamic changes to the
sub-nuclear compartmentalization of MCM2 as cells pass through late G1 and early S phase,
identifying a brief window when MCM2 becomes transiently attached to the nuclear-matrix.
The data distinguish 3 states that correspond to loose association with chromatin prior to
DNA replication, transient highly stable binding to the nuclear-matrix coincident with
initiation, and a post-initiation phase when MCM2 remains tightly associated with
chromatin but not the nuclear-matrix. The data suggests that functional MCM complex
loading takes place at the nuclear-matrix. 相似文献
14.
BACKGROUND: Benzo(a)pyrene (BaP), anthracene (ANTH) and chrysene (CHRY) are polynuclear aromatic hydrocarbons (PAHs) implicated in renal toxicity and carcinogenesis. These PAHs elicit cell type-specific effects that help predict toxicity outcomes in vitro and in vivo. While BaP and ANTH selectively injure glomerular mesangial cells, and CHRY targets cortico-tubular epithelial cells, binary or ternary mixtures of these hydrocarbons markedly reduce the overall cytotoxic potential of individual hydrocarbons. METHODS: To study the biochemical basis of these antagonistic interactions, renal glomerular mesangial cells were challenged with BaP alone (0.03 - 30 microM) or in the presence of ANTH (3 microM) or CHRY (3 microM) for 24 hr. Total RNA and protein will be harvested for Northern analysis and measurements of aryl hydrocarbon hydroxylase (AHH) and ethoxyresorufin-O-deethylase (EROD) activity, respectively, to evaluate cytochrome P450 mRNA and protein inducibility. Cellular hydrocarbon uptake and metabolic profiles of PAHs were analyzed by high performance liquid chromatography (HPLC). RESULTS: Combined hydrocarbon treatments did not influence the cellular uptake of individual hydrocarbons. ANTH or CHRY strongly repressed BaP-inducible cytochrome P450 mRNA and protein expression, and markedly inhibited oxidative BaP metabolism. CONCLUSION: These findings indicate that antagonistic interactions among nephrocarcinogenic PAHs involve altered expression of cytochrome P450s that modulate bioactivation profiles and nephrotoxic/ nephrocarcinogenic potential. 相似文献
15.
Stafford JA Pacofsky GJ Cox RF Cowan JR Dorsey GF Gonzales SS Jung DK Koszalka GW McIntyre MS Tidwell JH Wiard RP Feldman PL 《Bioorganic & medicinal chemistry letters》2002,12(21):3215-3218
The synthesis and evaluation of novel ultrashort-acting benzodiazepine (USA BZD) agonists is described. A BZD scaffold was modified by incorporation of amino acids and derivatives. The propionate side chain of glutamic acid tethers an enzymatically labile functionality where the metabolite carboxylic acid displays markedly reduced BZD receptor affinity. The USA BZDs were characterized by full agonism profiles. Copyright2000 Elsevier Science Ltd. 相似文献
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17.
Jeff W Higdon Olaf RP Bininda-Emonds Robin MD Beck Steven H Ferguson 《BMC evolutionary biology》2007,7(1):216
Background
Phylogenetic comparative methods are often improved by complete phylogenies with meaningful branch lengths (e.g., divergence dates). This study presents a dated molecular supertree for all 34 world pinniped species derived from a weighted matrix representation with parsimony (MRP) supertree analysis of 50 gene trees, each determined under a maximum likelihood (ML) framework. Divergence times were determined by mapping the same sequence data (plus two additional genes) on to the supertree topology and calibrating the ML branch lengths against a range of fossil calibrations. We assessed the sensitivity of our supertree topology in two ways: 1) a second supertree with all mtDNA genes combined into a single source tree, and 2) likelihood-based supermatrix analyses. Divergence dates were also calculated using a Bayesian relaxed molecular clock with rate autocorrelation to test the sensitivity of our supertree results further. 相似文献18.
19.
TL Kieft EM Murphy DL Haldeman PS Amy BN Bjornstad EV McDonald DB Ringelberg DC White J Stair RP Griffiths TC Gsell WE Holben DR Boone 《Microbial ecology》1998,36(3):336-348
Abstract Two chronosequences of unsaturated, buried loess sediments, ranging in age from <10,000 years to >1 million years, were investigated to reconstruct patterns of microbial ecological succession that have occurred since sediment burial. The relative importance of microbial transport and survival to succession was inferred from sediment ages, porewater ages, patterns of abundance (measured by direct counts, counts of culturable cells, and total phospholipid fatty acids), activities (measured by radiotracer and enzyme assays), and community composition (measured by phospholipid fatty acid patterns and Biolog substrate usage). Core samples were collected at two sites 40 km apart in the Palouse region of eastern Washington State, near the towns of Washtucna and Winona. The Washtucna site was flooded multiple times during the Pleistocene by glacial outburst floods; the Winona site elevation is above flood stage. Sediments at the Washtucna site were collected from near surface to 14.9 m depth, where the sediment age was approximately 250 ka and the porewater age was 3700 years; sample intervals at the Winona site ranged from near surface to 38 m (sediment age: approximately 1 Ma; porewater age: 1200 years). Microbial abundance and activities declined with depth at both sites; however, even the deepest, oldest sediments showed evidence of viable microorganisms. Same-age sediments had equal quantities of microorganisms, but different community types. Differences in community makeup between the two sites can be attributed to differences in groundwater recharge and paleoflooding. Estimates of the microbial community age can be constrained by porewater and sediment ages. In the shallower sediments (<9 m at Washtucna, <12 m at Winona), the microbial communities are likely similar in age to the groundwater; thus, microbial succession has been influenced by recent transport of microorganisms from the surface. In the deeper sediments, the populations may be considerably older than the porewater ages, since microbial transport is severely restricted in unsaturated sediments. This is particularly true at the Winona site, which was never flooded. 相似文献
20.
Cultured rat schwann cells grown in association with sensory neurons when labeled with [(3)H]leucinem, [(3)H]glucosamine, or [(35)S]methionine release labeled polypeptides into the culture medium. Analysis by SDS-polyacrylamide gel electrophoresis (SDS-PAGE) of the culture medium reveals a reproducible pattern of more than 20 polypeptides with molecular weights ranging from 15,000 to more than 250,000. Five major polypeptides (apparent molecular weights 225,000, 210,000, 90,000, 66,000, 50,000, and 40,000) account for approximately 40 percent of the leucine or methionine radioactivity in medium polypeptide. Schwann cells grown in a serum-free defined medium, in which schwann cells do not relate normally to axons, release approximately four times less labeled medium polypeptides tha cultures grown in medium supplemented with serum and chick embryo extract. In addition, there is a qualitative difference in the pattern of medium polypeptides resolved by SDS-PAGE, so that a single polypeptide (mol wt 40,000) accounts for nearly all of the label in medium polypeptides. Switching of cultures grown in defined medium to supplemented medium for 2 d results in a fourfold increase in the amount of labeled polypeptides appearing in the culture medium, and a return to the normal pattern of medium polypeptides appearing in the culture medium, and a return to the normal pattern of medium polypeptides as resolved by SDS-PAGE. This change in the pattern of polypeptides release by schwann cells is accompanied by changes in the association between schwann cells and axons. An early step in the establishment of normal axon-schwann cell relations appears to be an inward migration of schwann cells into axonal bundles and spreading of schwann cells along neurites. These changes are evident within 48 h after medium shift. Our results thus suggest that the release of proteins by schwann cells may be important for the development of normal axonal ensheathment. 相似文献