Detection of bacteria in suspension by using a superconducting quantum interference device.

We demonstrate a technique for detecting magnetically labeled Listeria monocytogenes and for measuring the binding rate between antibody-linked magnetic particles and bacteria. This sensitive assay quantifies specific bacteria in a sample without the need to immobilize them or wash away unbound magnetic particles. In the measurement, we add 50-nm-diameter superparamagnetic magnetite particles, coated with antibodies, to an aqueous sample containing L.

Pectate distribution and esterification in Dubautia leaves and soybean nodules, studied with a fluorescent hybridization probe.

Carbohydrate-hybridization probes (Vreeland and Laetsch, 1989, Planta (177, 423-434) were used to localize the homogalacturonan (pectate) component of pectins in the cell walls of leaves and soybean root nodules. Leaves of two species of the dicotyledon Dubautia were compared; these species contain much pectin but differ in their tissue water relations with respect to their cell-wall properties. Maturation of the primary cell walls in nodules was studied in the Bradyrhizobium japonicum-Glycine max symbiosis.

Identification of associating carbohydrate sequences with labelled oligosaccharides : Localization of alginate-gelling subunits in cells walls of a brown alga.

The gelling subunit of alginate, the major cell-wall polysaccharide of brown algae, was used as a molecular marker for identification of this cell-wall carbohydrate subunit at the cellular level. Short polyguluronate chains were conjugated to fluorescein and used as a probe to identify the gelling regions of alginate in tissue sections from a brown alga. The specificity of the probe for gelling subunits was demonstrated by lack of cell-wall labelling in the absence of calcium, correlation between divalent-cation binding affinities of polyguluronate with labelling intensity, and lack of labelling by fluorescein-conjugated nongelling subunits.

Monoclonal antibodies as molecular probes for cell wall antigens of the brown alga, Fucus.

Monoclonal antibodies to cell wall carbohydrates were produced against carbohydrates extracted from the brown alga, Fucus distichus ssp. edentatus (de la Pyl.) Powell.