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Exponentially growing cultures ofNitrosomonas europaea were inhibited by addition of 0.5 g nitrapyrin ml–1. This inhibition was increased by simultaneous addition of 0.046 g Cu2+ ml–1 as copper sulfate. This contradicts a previous report that copper relieves inhibition of ammonia oxidation by nitrapyrin, which report has formed the basis for hypotheses regarding the mechanism of action of this inhibitor. 相似文献
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The d. c. conductivity of five samples of NaDNA in dry state was investigated. All specimens show similar behavior, with specific resistivity at 40°C of the order of 1013–1014 ohm-cm and an energy gap of Ec = 2.04–2.25 eV. Based on the Eley's model for conductivity mechanism, the possibility of conservation of an ordered structure in the dry state (temperature range 20–80°C) is discussed. This is ascribed to the interaction of electron systems of individual bases. From the activation energy values it may be estimated that 17–19 π-electrons take part in the interaction. Photoconductivity measurements indicated activation energies Ef of 0.88–0.96 eV in the visible region. 相似文献
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Luminescence-based nonextractive technique for in situ detection of Escherichia coli in soil 总被引:2,自引:0,他引:2
E A Rattray J I Prosser K Killham L A Glover 《Applied and environmental microbiology》1990,56(11):3368-3374
Measurement of light output by luminometry was used to estimate quantitatively the cell concentrations of luminescent strains of Escherichia coli in liquid culture and inoculated into soil. Strains were constructed in which luciferase production was autoinducible or constitutive. In the former, light output per cell varied considerably during growth but was constant in constitutive strains. In liquid culture, the lower detection limit was in the order of 10(2) cells ml-1. Sensitivity was reduced by approximately 1 order of magnitude for cells inoculated into soil, when 2 x 10(2) to 6 x 10(3) cells g of soil-1 could be detected. Light output measurements were obtained within 5 min of sampling, and luminometry therefore potentially offers a rapid and sensitive detection technique for genetically engineered microorganisms. 相似文献
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Human satellite I sequences include a male specific 2.47 kb tandemly repeated unit containing one Alu family member per repeat 总被引:6,自引:1,他引:5 下载免费PDF全文
A portion of human satellite I DNA is digested by HinfI into three fragments of 775, 875 and 820bp in length which form a tandemly repeated unit 2.47kb in length, specific to male DNA. One Alu family member per repeat is found within the relatively G+C rich 775bp fragment. The 875 and 820bp fragments are highly A+T rich and consist of long stretches of poly dAdT and related sequences. 相似文献
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Luminescence-based nonextractive technique for in situ detection of Escherichia coli in soil. 总被引:9,自引:7,他引:2 下载免费PDF全文
Measurement of light output by luminometry was used to estimate quantitatively the cell concentrations of luminescent strains of Escherichia coli in liquid culture and inoculated into soil. Strains were constructed in which luciferase production was autoinducible or constitutive. In the former, light output per cell varied considerably during growth but was constant in constitutive strains. In liquid culture, the lower detection limit was in the order of 10(2) cells ml-1. Sensitivity was reduced by approximately 1 order of magnitude for cells inoculated into soil, when 2 x 10(2) to 6 x 10(3) cells g of soil-1 could be detected. Light output measurements were obtained within 5 min of sampling, and luminometry therefore potentially offers a rapid and sensitive detection technique for genetically engineered microorganisms. 相似文献