A preservable two color staining procedure to detect toxicant impacts on algae (Selenastrum capricornutum) using flow cytometry
- Univ. of Guelph, Ontario (Canada). Dept. of Environmental Biology
Over the last several years, the use of flow cytometry to assess the impacts of toxicants on algae has increased. Previous studies have tested cell viability using chlorophyll autofluorescence or single stain flow cytometric analysis in fresh algal cultures. A rapid, two-color flow cytometric assay to evaluate viability and cytotoxicity of Selenastrum capricomutum in preserved samples is described. The staining procedure involved fluorescein diacetate, a fluorogenic esterase substrate cleaved in viable cells to fluorescein (green 525 nm) and ethidium homodimer-1 dye which passes through plasma membranes of compromised and dead cells staining DNA (red 620 nm). The auto fluorescence of chlorophyll-a (deep red 675 nm) was used to assess cell viability and examined for use as an internal comparison with the staining procedure. For storage, stained cells were fixed in glutaraldehyde, flash frozen in liquid nitrogen and stored frozen ({minus}20C) for assessment at a later date. Weekly analysis of stored samples showed that the fluorescence of fluorescein diacetate and ethidium homodimer-1 stained cells was stable under these conditions for the 2 months used in this study. A prepared culture of Selenastrum capricomutum containing a 50% (v/v) mixture of live and heat killed cells showed 36.1 % stained live, 13.2% as compromised, 12% unlabeled, and 38.7% dead algal cells. This two-color flow cytometric procedure has proven to be a reliable, sensitive assay to determine viability of Selenastrum capricomutum in preserved samples. The sensitivity of this dual-color assay and the ability to store samples for later analysis are significant improvements over current techniques. This method is being tested for detection of chemical induced algal cytotoxicity and for potential adaptations to field studies.
- OSTI ID:
- 218448
- Report Number(s):
- CONF-9511137--; ISBN 1-880611-03-1
- Country of Publication:
- United States
- Language:
- English
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