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671.
The hydrophobic interaction of β-galactosidase with Sepharose 4B substituted with 3,3′-diaminodipropylamine was studied in both batch and column experiments. The equilibrium and the binding rate constants were determined for different phosphate buffer concentrations. The equilibrium constants exhibit a hysteresis effect, i.e., desorption constants are less than adsorption constants, and the higher the ionic strength to start the desorption, the larger the effect. The rate data are not satisfactorily described by a simple reversible first-order model. The column chromatographic data are semiquantitatively described by a local equilibrium theory without axial dispersion or intraparticle diffusion. 相似文献
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673.
Strains derived from Salmonella typhimurium LT-2, which are used as tester strains in mutagenicity assays, show significant changes in biochemical phenotypes. The presence of plasmid pKM101 in these strains greatly increases both the frequency of these shifts as well as the spectrum of phenotypes involved. It is suggested that in plasmid-free strains these variations reflect the effects of endogeneously induced mutations which are amplified in the absence of a functional uvrB gene product. In plasmid-containing strains this genetic drift may be promoted further by the pKM101-coded error-prone DNA repair system. The observation of a plasmid-mediated genetic drift lends support to the suggestion that transposons may contribute to the carcinogenic process. 相似文献
674.
Evolutionary conservation of the immediate-early gene ZENK 总被引:3,自引:0,他引:3
675.
J. Barry Wright J. W. Costerton W. F. McCoy 《Journal of industrial microbiology & biotechnology》1988,3(3):139-146
Summary The growth of two strains ofPseudomonas aeruginosa in stirred batch cultures was monitored by optical density, DNA concentration, and acridine orange direct cell count measurements. Growth of adherent bacteria in pure culture was also observed on suspended glass discs by light and scanning electron microscopy. Strain MUCOID produced significant numbers of filamentous cells in broth culture and in the adherent population, while strain PAO 381 did not produce elongated cells. Filamentous growth of MUCOID could be prevented by the addition of 5 × 10–2 M Mg2+. However, the addition of 0.66 mM EDTA caused an increased proportion of the population (>50%) of MUCOID cells to become filamentous in broth culture. The results are discussed and related to theories regarding bacterial plasticity, and filamentation of normally bacillary cells. 相似文献
676.
An enzyme-linked lectin assay (ELLA) has been developed to detect specific carbohydrate units on the surface of unfixed cells. The assay may be read in standard ELISA plate readers, since the cell-bound enzyme-lectin conjugate is specifically eluted from the cells prior to development of the conjugate. ELLA, when read in an enzyme-linked immunosorbent assay (ELISA) plate reader, allows better detection and relative quantitation of specific surface carbohydrate units than is possible by standard immunofluorescence with fluorescein-conjugated lectins. 相似文献
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Stephen P. Wraight Daniel Molloy Hugo Jamnback Patricia McCoy 《Journal of invertebrate pathology》1981,38(1):78-87
Laboratory trials of Bacillus thuringiensis var. israelensis (serotype 14) and B. sphaericus strain 1593 against field-collected Aedes stimulans showed that susceptibility declined with increasing instar and decreasing temperature. Test results with B. sphaericus were more erratic than with B. thuringiensis, and the efficacy of the former declined more rapidly with decreasing temperature. B. thuringiensis was significantly more active than B. sphaericus under all treatment conditions. These results indicate that the effective use of this strain of B. sphaericus as a mosquito biological control agent may be limited to warm water situations against more susceptible species. 相似文献
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