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21.
22.
H Bartsch C Malaveille B Tierney P L Grover P Sims 《Chemico-biological interactions》1979,26(2):185-196
The mutagenic activities of benz[alpha]anthracene, 7-methylbenz[alpha]anthracene, 7,12-dimethylbenz[alpha]anthracene, 3-methylcholanthrene and benzo[alpha]pyrene, together with those of the trans-dihydrodiols derived from these hydrocarbons that would be expected to yield 'bay-region' vicinal diolepoxides on further metabolism have been examined in assays with S. typhimurium TA100 using post-mitochondrial supernatant fractions prepared from the livers of 3-methylcholanthrene-treated rats. Mutagenic activities obtained have been compared with: (a) the extents of reaction with DNA that occur in mouse skin following treatment with these hydrocarbons; (b) the carcinogenicities of the hydrocarbons expressed as Iball indices; (c) their activities as tumour-initiating agents on mouse skin. Close positive associations were found between the microsome-mediated mutagenicities of the dihydrodiols that could yield "bay-region" diol-epoxides and: (a) the extents of reaction with DNA in hydrocarbon-treated mouse skin; (b) the carcinogenic potencies of the parent hydrocarbons; although these correlations are not perfect, the mutagenic activities of the hydrocarbons themselves in microsome-mediated assays with S. typhimurium show no correlation with their extents of DNA binding on mouse skin and a poor correlation with their activities as initiating agents. These comparisons also indicated a statistically-significant positive correlation between carcinogenicity and the in vivo DNA binding on mouse skin treated with the hydrocarbons. Differences in the metabolic pathways by which polycyclic hydrocarbons are activated in vivo and in vitro are discussed in relation to the improved correlations found with the dihydrodiols. 相似文献
23.
A D MacNicoll P M Burden H Rattle P L Grover P Sims 《Chemico-biological interactions》1979,27(2-3):365-379
The formation of trans-dihydrodiols from dibenz[a,c]anthracene, dibenz[a,h]anthracene and chrysene by chemical oxidation in an ascorbic acid-ferrous sulphate-EDTA system and by rat-liver microsomal fractions has been studied using a combination of thin-layer (TLC) and high pressure liquid chromatography (HPLC) to separate the mixtures of isomeric dihydrodiols. The 1,2- and 3,4-dihydrodiols of dibenz[a,c]anthracene, the 1,2-,3,4- and 5,6-dihydrodiols of dibenz[a,h]anthracene and the 1,2-, 3,4- and 5,6-dihydrodiols of chrysene were formed in chemical oxidations. These dihydrodiols were also formed when the three parent hydrocarbons were metabolized by rat-liver microsomal fractions and, in addition, dibenz[a,c]anthracene yielded the 10,11-dihydrodiol. The 1,2- and 3,4-dihydrodiols of dibenz[a,c]anthracene have not been reported previously either as metabolites of the hydrocarbon or as products of chemical syntheses and the 5,6-dihydrodiol of chrysene was not detected in earlier metabolic studies. 相似文献
24.
Incubation of benzo[alpha] pyrene 4,5-oxide with poly(G) in neutral aqueous ethanol resulted in the formation of covalent adducts and in the production of free 4-hydroxybenzo[alpha]pyrene. This phenol, which was identified by its UV spectral properties and by its chromatographic characteristics, was also formed but at a much slower rate when the epoxide was incubated with DNA or with GMP. Phenol formation was not detected when benzo[alpha]-pyrene 4,5-oxide was incubated for prolonged periods in the presence of poly(A), poly(C) or poly(U) or in the absence of nucleic acid. Formation of 4-hydroxybenzo[alpha] pyrene from the epoxide in the presence of poly(G) was not accompanied by detectable base modifications or by breakage of phosphodiester linkages. 相似文献
25.
26.
Prey Food Quality Affects Flagellate Ingestion Rates 总被引:1,自引:3,他引:1
Flagellate feeding efficiency appears to depend on morphological characteristics of prey such as cell size and motility, as
well as on other characteristics such as digestibility and cell surface characteristics. Bacteria of varying morphological
characteristics (cell size) and mineral nutrient characteristics or food quality (as determined by the C:N:P ratio) were obtained
by growing Pseudomonas fluorescens in chemostats at four dilution rates (0.03, 0.06, 0.10, and 0.13 h−1) and three temperatures (14°C, 20°C, and 28°C). Cells of a given food quality were heat-killed and used to grow the flagellate
Ochromonas danica. Ingestion and digestion rates were determined by using fluorescently labeled bacteria of the same food quality as the bacteria
supporting growth. Ingestion rates were affected by both food quality and cell size. Cells of high food quality (low carbon:element
ratio) were ingested at higher rates than cells of low food quality. Multiple regression analysis indicated that cell size
also influenced ingestion rate but to a much lesser extent than did food quality. Digestion rates were not correlated with
either food quality or cell size. Results suggest that flagellates may adjust feeding efficiency based on the quality of food
items available. 相似文献
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28.
Ranjeet R. Kumar Suneha Goswami Mohammad Shamim Kavita Dubey Khushboo Singh Shweta Singh Yugal K. Kala Ravi R.K. Niraj Akshay Sakhrey Gyanendra P. Singh Monendra Grover Bhupinder Singh Gyanendra K. Rai Anil K. Rai Viswanathan Chinnusamy Shelly Praveen 《Functional & integrative genomics》2017,17(6):621-640
29.
Most microfluidic chips utilize off-chip hardware (syringe pumps, computer-controlled solenoid valves, pressure regulators, etc.) to control fluid flow on-chip. This expensive, bulky, and power-consuming hardware severely limits the utility of microfluidic instruments in resource-limited or point-of-care contexts, where the cost, size, and power consumption of the instrument must be limited. In this work, we present a technique for on-chip fluid control that requires no off-chip hardware. We accomplish this by using inert compounds to change the density of one fluid in the chip. If one fluid is made 2% more dense than a second fluid, when the fluids flow together under laminar flow the interface between the fluids quickly reorients to be orthogonal to Earth’s gravitational force. If the channel containing the fluids then splits into two channels, the amount of each fluid flowing into each channel is precisely determined by the angle of the channels relative to gravity. Thus, any fluid can be routed in any direction and mixed in any desired ratio on-chip simply by holding the chip at a certain angle. This approach allows for sophisticated control of on-chip fluids with no off-chip control hardware, significantly reducing the cost of microfluidic instruments in point-of-care or resource-limited settings. 相似文献
30.
Sajad Ali Zahoor Ahmad Mir Anshika Tyagi Javaid A. Bhat Narayanappa Chandrashekar Pradeep Kumar Papolu Sandhya Rawat Anita Grover 《Acta Physiologiae Plantarum》2017,39(12):268
Pathogenesis-related proteins (PRs) are the antimicrobial proteins which are commonly used as signatures of defense signaling pathways and systemic acquired resistance. However, in Brassica juncea most of the PR proteins have not been fully characterized and remains largely enigmatic. In this study, full-length cDNA sequences of SA (PR1, PR2, PR5) and JA (PR3, PR12 and PR13) marker genes were isolated from B. juncea and were named as BjPR proteins. BjPR proteins showed maximum identity with known PR proteins of Brassica species. Further, expression profiling of BjPR genes were investigated after hormonal, biotic and abiotic stresses. Pre-treatment with SA and JA stimulators downregulates each other signature genes suggesting an antagonistic relationship between SA and JA in B. juncea. After abscisic acid (ABA) treatment, SA signatures were downregulated while as JA signature genes were upregulated. During Erysiphe cruciferarum infection, SA- and JA-dependent BjPR genes showed distinct expression pattern both locally and systemically, thus suggesting the activation of SA- and JA-dependent signaling pathways. Further, expression of SA marker genes decreases while as JA-responsive genes increases during drought stress. Interestingly, both SA and JA signature genes were induced after salt stress. We also found that BjPR genes displayed ABA-independent gene expression pattern during abiotic stresses thus providing the evidence of SA/JA cross talk. Further, in silico analysis of the upstream regions (1.5 kb) of both SA and JA marker genes showed important cis-regulatory elements related to biotic, abiotic and hormonal stresses. 相似文献