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21.
Robert J. Mauthe Glenn A. Marsch Kenneth W. Turteltaub 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1996,679(1-2)
An improved HPLC-based 32P-postlabeling assay has been developed for the analysis of DNA modified with the food carcinogen 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP). Postlabeled samples are loaded onto a C18 precolumn and adducted bases are retained while excess radioactivity and unmodified DNA bases are eluted directly to waste through a switching valve. The use of this HPLC in-line precolumn purification (HIPP) technique allows entire postlabeled samples to be analyzed without prior removal of inorganic phosphate and unmodified DNA bases. The method has a sample to sample precision of 15% and accuracy of 20%, at adduct levels of 2 adducts/107 bases and shows a linear relationship between signal and adduction levels from 1 adduct per 104 to ≈ 2±1 adducts per 109 bases. Individual postlabeled DNA samples can be analyzed by HPLC in less than 1 h, allowing high throughput. The use of calf-thymus DNA (CT-DNA), highly modified with PhIP, or DNA isolated from mice chronically fed a PhIP-modified diet shows two major PhIP-DNA adduct peaks and three additional minor adduct peaks when labeled under ATP-limiting conditions. Isolation of the HPLC purified peaks and analysis by thin layer chromatography (TLC) matches the five HPLC peaks to the spots typically seen by TLC, including N-(deoxyguanosin-8-yl)-2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (dG-C8-PhIP). Variations in digestion techniques indicate a potential resistance of the PhIP-DNA adducts to the standard enzymatic digestion methods. Attempts at adduct intensification by solid phase extraction, nuclease P1 enrichment or 1-butanol extraction decreased PhIP-DNA adduct peaks and introduced a large early eluting peak. Removal of the 3′-phosphate with nuclease P1 following the kinase labeling reaction simplifies the HPLC profile to one major peak (dG-C8-PhIP monophosphate) with several minor peaks. In addition to the high resolution provided by HPLC separation of the PhIP-DNA adducts, this method can be adjusted for analysis of other DNA adducts and is readily automated for high throughput. 相似文献
22.
Rocio J. Alcántara-Hernández César Valenzuela-Encinas Rodolfo Marsch Luc Dendooven 《Extremophiles : life under extreme conditions》2009,13(1):169-178
The diversity of the dissimilatory and respiratory nitrate-reducing communities was studied in two soils of the former lake
Texcoco (Mexico). Genes encoding the membrane-bound nitrate reductase (narG) and the periplasmic nitrate reductase (napA) were used as functional markers. To investigate bacterial communities containing napA and narG in saline alkaline soils of the former lake Texcoco, libraries of the two sites were constructed (soil T3 with pH 11 and
electrolytic conductivity in saturated extract (ECSE) 160 dS m−1 and soil T1 with pH 8.5 and ECSE 0.8 dS m−1). Phylogenetic analysis of napA sequences separated the clone families into two main groups: dependent or independent of NapB. Most of napA sequences from site T1 were grouped in the NapB-dependent clade, meanwhile most of the napA sequences from the extreme soil T3 were affiliated to the NapB-independent group. For both sites, partial narG sequences were associated with representatives of the Proteobacteria, Firmicutes and Actinobacteria phyla, but the proportions of the clones were different. Our results support the concept of a specific and complex nitrate-reducing
community for each soil of the former lake Texcoco. 相似文献
23.
Adriana Garay‐Arroyo Enrique Ortiz‐Moreno María de la Paz Sánchez Angus S Murphy Berenice García‐Ponce Nayelli Marsch‐Martínez Stefan de Folter Adriana Corvera‐Poiré Fabiola Jaimes‐Miranda Mario A Pacheco‐Escobedo Joseph G Dubrovsky Soraya Pelaz Elena R Álvarez‐Buylla 《The EMBO journal》2013,32(21):2884-2895
24.
Betancur-Galvis LA Carrillo H Luna-Guido M Marsch R Dendooven L 《International journal of phytoremediation》2012,14(8):741-753
Remediation of polycyclic aromatic hydrocarbons (PAHs) contaminated alkaline saline soil with phreatophyte or "water loving plants" was investigated by spiking soil from the former lake Texcoco with 100 mg phenanthrene (Phen) kg(-1) soil, 120 mg anthracene (Ant)kg(-1) soil and 45 mg benzo(a)pyrene (BaP) kg(-1) soil and vegetating it with Athel tamarisk (Tamarix aphylla L Karst.). The growth of the Athel tamarisk was not affected by the PAHs. In soil cultivated with Athel tamarisk, the leaching of PAHs to the 32-34 cm layer decreased 2-fold compared to the uncultivated soil. The BaP concentration decreased to 39% of the initial concentration at a distance smaller than 3 cm from the roots and to 45% at a distance larger than 3cm, but 59% remained in unvegetated soil after 240 days. Dissipation of Ant and Phen decreased with depth, but not BaP. The biodegradation of PAHs was affected by their chemical properties and increased in the presence of T. aphylla, but decreased with depth. 相似文献
25.
U. Geyer Th. Heinze A. Stein D. Klemm S. Marsch D. Schumann H.-P. Schmauder 《International journal of biological macromolecules》1994,16(6):343-347
Acetobacter xylinum produces highly crystalline cellulose extracellulary using glucose as a carbon source. The polymer formed is free of other biogenic compounds, separable in a simple way and characterized by its high water-absorption capacity. Stepwise solvent exchange from water to unpolar solvents leads to a drastic decrease of the water content of the bacterial cellulose without decrease of the highly swollen and activated state. Heterogeneous as well as homogeneous derivatizations, e.g. carboxymethylation, silylation and acetylation, were performed on the wet or dried biopolymer. Furthermore, different methods for formation of hollow fibres during biosynthesis were investigated. Such tubes may have applications as biocompatible material in medicine. 相似文献
26.
E Calva R Nú?ez E Briones M Marsch 《Comparative biochemistry and physiology. B, Comparative biochemistry》1978,61(1):173-179
1. Dog heart tissue suspension hydrolyzes NAD, NADP and NMN, and releases nicotinamide stoichiometrically. 2. Maximum activity was observed at 50 degrees C and the activation energy was 10 kcal/mol. 3. Optimum pH range was 6.2-7.6. 4. Compounds with adenine-ribose moiety increased the enzymatic activity. 5. Nicotinamide released during incubation produced reaction nonlinearity. 6. Km for NAD and NADP were about the same; Vmax was higher for NAD. Similar findings have been reported for rabbit heart. 7. Dog enzyme appears to be more sensitive than the rabbit enzyme to noncompetitive inhibitors. 8. Pyrophosphatase activity was not detected in dog heart in contrast to rabbit and rat heart preparations. 相似文献
27.
Changes in the bacterial populations of the highly alkaline saline soil of the former lake Texcoco (Mexico) following flooding 总被引:4,自引:0,他引:4
César Valenzuela-Encinas Isabel Neria-González Rocio J. Alcántara-Hernández Isabel Estrada-Alvarado Francisco Javier Zavala-Díaz de la Serna Luc Dendooven Rodolfo Marsch 《Extremophiles : life under extreme conditions》2009,13(4):609-621
Flooding an extreme alkaline-saline soil decreased alkalinity and salinity, which will change the bacterial populations. Bacterial
16S rDNA libraries were generated of three soils with different electrolytic conductivity (EC), i.e. soil with EC 1.7 dS m−1 and pH 7.80 (LOW soil), with EC 56 dS m−1 and pH 10.11 (MEDIUM soil) and with EC 159 dS m−1 and pH 10.02 (HIGH soil), using universal bacterial oligonucleotide primers, and 463 clone 16S rDNA sequences were analyzed
phylogenetically. Library proportions and clone identification of the phyla Proteobacteria, Actinobacteria, Acidobacteria, Cyanobacteria, Bacteroidetes, Firmicutes and Cloroflexi showed that the bacterial communities were different. Species and genera of the Rhizobiales, Rhodobacterales and Xanthomonadales
orders of the α- and γ-subdivision of Proteobacteria were found at the three sites. Species and genera of the Rhodospirillales, Sphingobacteriales, Clostridiales, Oscillatoriales
and Caldilineales were found only in the HIGH soil, Sphingomonadales, Burkholderiales and Pseudomonadales in the MEDIUM soil,
Myxococcales in the LOW soil, and Actinomycetales in the MEDIUM and LOW soils. It was found that the largest diversity at
the order and species level was found in the MEDIUM soil as bacteria of both the HIGH and LOW soils were found in it. 相似文献
28.
Ruiz-Romero E. Alcántara-Hernández R. Cruz-Mondragon C. Marsch R. Luna-Guido M. L. Dendooven L. 《Plant and Soil》2009,319(1-2):247-257
Plant and Soil - Extreme alkalinity and salinity affects different processes involved in the N cycle, such as mineralization and nitrification, so it might affect the denitrification process and... 相似文献
29.
Changes in methane oxidation activity and methanotrophic community composition in saline alkaline soils 总被引:2,自引:0,他引:2
Nancy Serrano-Silva César Valenzuela-Encinas Rodolfo Marsch Luc Dendooven Rocio J. Alcántara-Hernández 《Extremophiles : life under extreme conditions》2014,18(3):561-571
The soil of the former Lake Texcoco is a saline alkaline environment where anthropogenic drainage in some areas has reduced salt content and pH. Potential methane (CH4) consumption rates were measured in three soils of the former Lake Texcoco with different electrolytic conductivity (EC) and pH, i.e. Tex-S1 a >18 years drained soil (EC 0.7 dS m?1, pH 8.5), Tex-S2 drained for ~10 years (EC 9.0 dS m?1, pH 10.3) and the undrained Tex-S3 (EC 84.8 dS m?1, pH 10.3). An arable soil from Alcholoya (EC 0.7 dS m?1, pH 6.7), located nearby Lake Texcoco was used as control. Methane oxidation in the soil Tex-S1 (lowest EC and pH) was similar to that in the arable soil from Alcholoya (32.5 and 34.7 mg CH4 kg?1 dry soil day?1, respectively). Meanwhile, in soils Tex-S2 and Tex-S3, the potential CH4 oxidation rates were only 15.0 and 12.8 mg CH4 kg?1 dry soil day?1, respectively. Differences in CH4 oxidation were also related to changes in the methane-oxidizing communities in these soils. Sequence analysis of pmoA gene showed that soils differed in the identity and number of methanotrophic phylotypes. The Alcholoya soil and Tex-S1 contained phylotypes grouped within the upland soil cluster gamma and the Jasper Ridge, California JR-2 clade. In soil Tex-S3, a phylotype related to Methylomicrobium alcaliphilum was detected. 相似文献
30.
Etiopathogenetic regulatory disorders of epidermal metabolism and the subsequent changes in the molecular pattern of the stratum corneum play an important role in the clinical differentiation of particular dermatoses (e.g., psoriasis, atopic dermatitis). In this study we present in vitro Fourier transform Raman spectra of the stratum corneum from healthy skin, as well as from clinically undiseased skin of the right heel of atopic and psoriatic volunteers. Differences in the averaged spectra were detected, particularly in the spectral ranges of 1112-1142 (lipid band), 1185-1220, and 1394-1429 cm(-1). By using the first derivative of the averaged spectra and/or a statistical evaluation of the spectroscopic data it was possible to distinguish the skin types examined. 相似文献