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As more and more genome sequences are completed, it is becoming increasingly evident that our understanding of the function of most bacterial gene products is lacking. This is frustrating, particularly in the study of pathogens, where an understanding of the role of individual gene products would probably facilitate the development of novel antimicrobials and vaccines. Recently, we devised a technique known as virulence-attenuated pool (VAP) screening to help assign genetic functionality to gene products that the pathogen Vibrio cholerae requires for colonization. This screen and potential new applications of the VAP technique are discussed here. 相似文献
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Heather L. Tierney April D. Jewell Ashleigh E. Baber Erin V. Iski E. Charles H. Sykes 《Chirality》2012,24(12):1051-1054
Symmetry breaking by photons, electrons, and molecular interactions lies at the heart of many important problems as varied as the origin of homochiral life to enantioselective drug production. Herein we report a system in which symmetry breaking can be induced and measured in situ at the single‐molecule level using scanning tunneling microscopy. We demonstrate that electrical excitation of a prochiral molecule on an achiral surface produces large enantiomeric excesses in the chiral adsorbed state of up to 39%. The degree of symmetry breaking was monitored as a function of scanning probe tip state, and the results revealed that enantiomeric excesses are correlated with the intrinsic chirality in scanning probe tips themselves, as evidenced by height differences between single molecule enantiomers. While this work has consequences for the study of two‐dimensional chirality, more importantly, it offers a new method for interrogating the coupling of photons, electrons, and combinations of physical fields to achiral starting systems in a reproducible manner. This will allow the mechanism of chirality transfer to be studied in a system in which enantiomeric excesses are quantified accurately by counting individual molecules. Chirality 24:1051–1054, 2012. © 2012 Wiley Periodicals, Inc. 相似文献
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A rapid and cost efficient technique was developed and used to generate 168 sequence tagged microsatellites (STMs) in the barley scald pathogen Rhynchosporium secalis. Sixty‐two STMs, amplifying 66 loci, revealed a high level of polymorphism among a diverse set of 16 Australian isolates. Each locus revealed two to nine alleles (average 4 ± 1.82), and a gene diversity measure of 0.54 was obtained. This technique not only halved the cost of marker development compared to traditional methods, but substantially reduced the cost of performing fluorescence‐based microsatellite assays. These STMs provide a powerful tool for genetic studies in R. secalis. 相似文献
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The feeding of carcinogenic 3'-methyl-4-dimethylaminoazobenzene (3'-MeDAB) in the early stages results in a change in the protein composition of the nuclear ribonucleoprotein particles of the rat liver. These particles are associated with newly synthesized RNA and it is assumed that they are involved in the processing and in the transport of this RNA. After 6 weeks of feeding of this azocarcinogen, the amount of one of the main polypeptides (apparent molecular weight 42 000) is decreased and after 10 weeks of feeding the particles are devoid of this polypeptide completely. Feeding of the non-carcinogenic p-aminoazobenzene (AB) is without any effect. The loss of this polypeptide is not characteristic for the malignant transformation. In the nuclear ribonucleoprotein particles isolated from hepatoma which has been induced by 3'-MeDAB this polypeptide is present in even higher proportion to other polypeptides than it is in particles isolated from liver cells of control animals. The 3'-MeDAB binds to the proteins of the liver nuclear ribonucleoprotein particles and interferes with the RNA processing. It is proposed that the changes in the composition of the protein moiety of the particles reflect changes in the population of liver cells leading finally to the selection of hepatoma cells which are resistant to the toxic effect of 3'-MeDAB on RNA processing. 相似文献
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