Single-cell quantification of molecules and rates using open-source microscope-based cytometry.

Microscope-based cytometry provides a powerful means to study cells in high throughput. Here we present a set of refined methods for making sensitive measurements of large numbers of individual Saccharomyces cerevisiae cells over time. The set consists of relatively simple 'wet' methods, microscope procedures, open-source software tools and statistical routines.

Regulated cell-to-cell variation in a cell-fate decision system.

Here we studied the quantitative behaviour and cell-to-cell variability of a prototypical eukaryotic cell-fate decision system, the mating pheromone response pathway in yeast. We dissected and measured sources of variation in system output, analysing thousands of individual, genetically identical cells. Only a small proportion of total cell-to-cell variation is caused by random fluctuations in gene transcription and translation during the response ('expression noise').

Haptens and monoclonal antibodies for immunoassay of imidazolinone herbicides.

A set of haptens structurally resembling the herbicide imazethapyr (PURSUIT) was synthesized and used to derive monoclonal antibodies (MAbs) and direct and indirect competition enzyme immunoassays (EIAs) which could detect imazethapyr, imazaquin (SCEPTER), imazapic (CADRE), and imazamox (RAPTOR) in the 3-30 ng/mL (parts per billion) range, and imazapyr (ARSENAL) and imazamethabenz-methyl (ASSERT) in the 300-500 ppb range. Two MAbs, 3A2 and 3A5, had affinities of 10-75 nM for imazethapyr. MAbs 1A5, 1D2, and 3A5 were specific for the S isomers of the herbicides.