title: Nile Red staining of phytoplankton neutral lipids: species-specific fluorescence kinetics in various solvents.
abstract: Nile Red (NR) staining potentially offers a simple method for monitoring lipid accumulation in microalgal cultivation. However, variable staining efficiencies and methods have been reported. The effect of dimethyl sulfoxide (DMSO), ethylene glycol (EG) and glycerol on NR penetration with four different phytoplankton species representing different taxonomical groups was studied. Treatment with the solvents enhanced the NR fluorescence of the diatomPhaeodactylum tricornutumduring kinetic fluorescence measurements, but high concentrations of solvents were needed. None of the solvents improved NR staining of the green algaChlorella pyrenoidosaandScenedesmus obliquus, which are known to be difficult to stain due to their thick and rigid cell walls. The nakedIsochrysissp. cells stained best without solvents. The results confirm that NR staining protocol needs to be optimized for each species.
authors.affiliation: Marine Research Centre, Finnish Environment Institute, Erik Palménin aukio 1, P.O. Box 140, 00251 Helsinki, Finland.
authors.forename: Katariina
authors.initials: K
authors.lastname: Natunen
authors.affiliation: Marine Research Centre, Finnish Environment Institute, Erik Palménin aukio 1, P.O. Box 140, 00251 Helsinki, Finland.
authors.forename: Jukka
authors.initials: J
authors.lastname: Seppälä
authors.affiliation: VTT Technical Research Centre of Finland, Tietotie 2, 02044 Espoo, Finland.
authors.forename: Dagmar
authors.initials: D
authors.lastname: Schwenk
authors.affiliation: VTT Technical Research Centre of Finland, Tietotie 2, 02044 Espoo, Finland.
authors.forename: Heiko
authors.initials: H
authors.lastname: Rischer
authors.affiliation: Marine Research Centre, Finnish Environment Institute, Erik Palménin aukio 1, P.O. Box 140, 00251 Helsinki, Finland.
authors.forename: Kristian
authors.initials: K
authors.lastname: Spilling
authors.affiliation: Marine Research Centre, Finnish Environment Institute, Erik Palménin aukio 1, P.O. Box 140, 00251 Helsinki, Finland.
authors.forename: Timo
authors.initials: T
authors.lastname: Tamminen
keywords: Fluorescence kinetics; Neutral lipids; Nile Red; Phytoplankton; Solvents