FIG. 1.

PCR amplification of the NMT region of microcystin synthetase from an environmental bloom. The NMT-specific PCR was performed using DNAs isolated from the Botany Ponds cyanobacterial bloom samples collected in 1993 on the dates (day/month) indicated. Samples that proved to be toxic (T) or nontoxic (NT) by the phosphatase inhibition assay (1) are indicated. Five-microliter aliquots of each PCR mixture were run on a 2% agarose gel in 1× Tris-acetate-EDTA together with 100 ng of Spp-1 DNA digested with EcoRI. The gel was stained with ethidium bromide and photographed under UV transillumination.