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Advisor(s)
Abstract(s)
The present work describes the optimization
of a short-term assay, based on the inhibition of
the esterase activity of the alga Pseudokirchneriella
subcapitata, in a microplate format. The optimization
of the staining procedure showed that the incubation
of the algal cells with 20 μmolL−1 fluorescein diacetate
(FDA) for 40 min allowed discrimination between
metabolic active and inactive cells. The shortterm
assay was tested using Cu as toxicant. For this
purpose, algal cells, in the exponential or stationary
phase of growth, were exposed to the heavy metal in
growing conditions. After 3 or 6 h, cells were subsequently
stained with FDA, using the optimized procedure.
For Cu, the 3- and 6-h EC50 values, based on the
inhibition of the esterase activity of algal cells in the
exponential phase of growth, were 209 and 130 μg
L−1, respectively. P. subcapitata cells, in the stationary
phase of growth, displayed higher effective concentration
values than those observed in the exponential phase. The 3- and 6-h EC50 values for Cu, for cells
in the stationary phase, were 443 and 268 μgL−1,
respectively. This short-term microplate assay showed
to be a rapid endpoint for testing toxicity using the
alga P. subcapitata. The small volume required, the
simplicity of the assay (no washing steps), and the
automatic reading of the fluorescence make the assay
particularly well suited for the evaluation of the toxicity
of a high number of environmental samples.
Description
Keywords
Bioassay Fluorescein diacetate (FDA) Growth phase Microplate assay Metabolic activity Selenastrum capricornutum
Citation
Publisher
Springer