title: Monitoring cell-specific neutral lipid accumulation in Phaeodactylum tricornutum (Bacillariophyceae) with Nile Red staining - a new method for FlowCAM.
abstract: With the fluorescent stain Nile Red (NR), phytoplankton lipid accumulation can be monitored quickly and in situ. In the light of recent results in phytoplankton diversity research, there is also a need for cell- and species-specific lipid measurement techniques. The objective of this work was to investigate whether cell-specific phytoplankton lipid accumulation could be monitored with the image-based particle analyzer FlowCAM™ and NR staining. Applying Phaeodactylum tricornutum as a model species, we compared the FlowCAM method to two established lipid quantification methods: spectrofluorometric NR fluorescence measurement and total lipid analysis by gas chromatography. The experiment was carried out in batch cultures under nitrogen limitation to induce lipid accumulation. We showed significant correlation between the three different lipid quantification methods confirming the applicability of the novel FlowCAM method in cell-specific and near real-time lipid quantification. Furthermore, with the method described here, the lipid content of taxonomically distinguished cells can eventually be measured from multispecies cultures, opening several new possibilities to study species-specific responses to stress conditions and the complementarity effect.
authors.affiliation: Marine Research Centre, Finnish Environment Institute (SYKE), Erik Palménin aukio 1, 00560, Helsinki, Finland.
authors.forename: Katariina
authors.identifier: 0000-0002-8770-1891
authors.initials: K
authors.lastname: Natunen
authors.affiliation: Marine Research Centre, Finnish Environment Institute (SYKE), Erik Palménin aukio 1, 00560, Helsinki, Finland.
authors.forename: Jukka
authors.initials: J
authors.lastname: Seppälä
authors.affiliation: Department of Environmental Sciences, University of Helsinki, Niemenkatu 73, 15140, Lahti, Finland.
authors.forename: Riikka-Juulia
authors.initials: RJ
authors.lastname: Koivula
authors.affiliation: Department of Environmental Sciences, University of Helsinki, Niemenkatu 73, 15140, Lahti, Finland.
authors.forename: Jukka
authors.initials: J
authors.lastname: Pellinen
mesh_terms: D001681:Biological Assay / Q000379:methods; D017377:Diatoms / Q000378:metabolism*; D050356:Lipid Metabolism / Q000502:physiology; D010078:Oxazines / Q000378:metabolism; D013050:Spectrometry, Fluorescence / Q000379:methods*
chemical_list: D010078:Oxazines; C044808:nile red
keywords: FlowCAM; Nile Red; cell-specific; neutral lipid; spectrofluorometer