Isolation and separation of nucleic acids from Streptomyces hydrogenans (author's transl)]

Different methods for homogenization of cells of Streptomyces hydrogenans, for extraction of nucleic acids and for fractionation of the RNA and DNA obtained were critically examined. The only way to prepare high molecular weight rapidly labelled RNA and polysomes was to grind freeze-dried cells together with kieselguhr with a mortar and pestle. The best results for extraction of nucleic acids from the cell homogenate were obtained in the presence of diethyl pyrocarbonate (diethyl oxydiformate), yielding nucleic acids of considerable purity in a minimal amount of time. The best resolution of extracted nucleic acids was achieved by electrophoresis in 2% agarose acrylamide gels. This technique proved that during the cell homogenization and extraction procedure the bulk of nucliec acids was not degraded to low molecular weight material. An improved device for the registration of the profile of the absorption after gel electrophoresis is described.     

Carbohydrate-limited Growth Kinetics of Tobacco (Nicotiana rustica L.) Callus

Logistic curves were fitted to sigmoidal growth data obtained from tobacco (Nicotiana rustica L.) callus grown on media prepared with 0.1, 0.03, 0.01, and 0.003 m sucrose. Analysis of the growth curves indicated that final yields and specific growth rates were influenced by the initial sucrose concentration. Growth yields from the four treatments were similar (0.61 +/- 0.04 gram dry tissue per gram sucrose supplied). Initial specific growth rates exhibited a Michaelis-Menten dependency on initial sucrose concentration such that the V(max) = 0.18 g g(-1) day(-1) and Km = 0.0037 m sucrose.     

A highly uniform UV transillumination imaging system for quantitative analysis of nucleic acids and proteins

The digital fluorescent imaging for documentation and analysis of gel electrophoretic separations of nucleic acids and proteins is widely used in quantitative biology. Most fluorescent stains used in postelectrophoretic analysis of proteins and nucleic acids have significant excitation peaks with UV light (300-365 nm), making midrange UV (UV-B) as the excitation source of choice. However, coupling quantitative CCD imaging with UV is difficult due to lack of uniformity found in typical UV transilluminators. The apparent amount of those macromolecules depends on the position of the gel band on the imaging surface of the transilluminator. Here, we report the development and validation of a highly uniform UV transillumination system. Using a novel high density lighting system containing a single lamp formed into a high density grid, an electronic ballast, a phosphor coating, and a bandpass filter to convert 254 nm light produced to 300-340 nm, uniformity of 80% CV observed in typical UV transilluminators. This system has been used for the quantitative analysis of electrophoretically separated nucleic acids and proteins (CV相似文献