Use of FDA and flow cytometry to assess metabolic activity as an indicator of nutrient status in phytoplankton
Justin D. Brookes, Sean M. Geary, George G. Ganf and Michael D. Burch
Marine and Freshwater Research
51(8) 817 - 823
This study reports the use of a technique to determine nutrient limitation of cultured and natural phytoplankton. The technique, an FDA-activity assay, which is usually used to assess cell viability, was used to measure metabolic activity in response to nutrient addition; the metabolic activity of phytoplankton was determined as the rate of hydrolysis of fluorescein diacetate (FDA), by intracellular esterases, to fluorescein, which was detectedusing a flow cytometer. Replacement of the limiting nutrient to nitrogen- or phosphorus-limited cultures and field populations resulted in an increase in metabolic activity that was detectable 24 h after nutrient addition. By flow cytometry, the natural phytoplankton community can be divided into different taxonomic groups; the response of these to FDA could be determined individually to allow identification of the nutrients limiting each type of phytoplankton. This would be more specific than the assessment of a whole-community response, which may mask subtle differences among taxa.
Full text doi:10.1071/MF00048
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