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W S Knight

Publications and source records attributed to W S Knight.

6 recordsLinked to original sources
PubMed1982

Radial partition immunoassay.

In radial partition immunoassay, radial chromatography is used for performing an immunoassay. We describe the application of this technology to the measurement of digoxin in serum by enzyme immunoassay, with the entire testing procedure carried out on glass-fiber filter paper. A sample is applied to a small central area of the filter paper, where it reacts with the antibody to digoxin immobilized there. Subsequently, enzyme-labeled digoxin is applied to react with remaining antibody sites. After incubation, substrate for the enzyme is applied to the center of the reaction area and washes out any unbound label to the periphery of the paper. This step also initiates the enzyme reaction, which is quantified by front-surface fluorescence. A microprocessor-controlled automated instrument has been developed to process the filter paper matrix through the above sequence, and calculate the final result. Total testing time for digoxin is less than 7 min.

Antibodies↗
PubMed1969

Functions of F pili in mating-pair formation and male bacteriophage infection studies by blending spectra and reappearance kinetics.

The extent of removal at various blending speeds (blending spectrum) and the kinetics of reappearance after blending of the ability of male Escherichia coli bacteria to form mating pairs, to adsorb and be infected by ribonucleic acid male phage, and to adsorb and be infected by deoxyribonucleic male phage were identical to the blending spectrum and reappearance kinetics of microscopically visible F pili. The same results were obtained with an Hfr (high-frequency recombinant), F', or resistance transfer factor (RTF) fi(+) mating system. Blending did not affect the viability, growth rate, ability to adsorb T4 phage, or ability to produce new F pili at any of the speeds used. It can be concluded that microscopically visible F pili are an absolute requirement for all three functions. Three classes of F pili have been found in bacterial cultures: attached, adsorbed, and free. Bacteria with adsorbed F pili in addition to attached ones were proportionately more susceptible to male phage infection, suggesting that adsorbed F pili may be at least partially functional. Free F pili did not compete with bacteria for phage. Some implications of the virus-like nature of F-pilus outgrowth for the mechanisms of mating and male phage infection are discussed.

Adsorption↗
PubMed1968

Inhibition of bacterial conjugation by ribonucleic acid and deoxyribonucleic acid male-specific bacteriophages.

Both deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) male-specific phages, with an F-specific host range, inhibited the bacterial mating process of Escherichia coli. DNA phages prevented the formation of mating pairs but had no effect on mating pairs once they were formed. A step in RNA phage infection, prior to RNA penetration, prevented the formation of mating pairs and, in addition, prevented a fraction of existing mating pairs from completing the mating process. These findings are compatible with the hypothesis that donor cells have a single surface structure involved in both conjugation and male-phage adsorption and that this element is the F pilus.

Binding Sites↗