title: Delayed fluorescence as a measure of nutrient limitation in Dunaliella tertiolecta.
abstract: The applicability of the delayed fluorescence (DF) for the purpose of distinguishing the cells growing in different nutrient conditions was researched on the marine unicellular algae Dunaliella tertiolecta Butcher (Chlorophyta). The DF intensity (DFI), as a measure of living algal biomass, was compared with other biomass measures--the cell concentration, chlorophyll a and fluorescence. The photosynthetic activity index (PhAI), a non-dimensional physiological index of photosynthesis calculated from a combination of DFI and F(0) was introduced. The nitrogen deprivation was indicated by more than 50% drop of PhAI. DF decay kinetics was measured with two different illuminations (<600 nm and >650 nm). The measured curves were divided and the resulting peak utilized for the differentiation among nutrient conditions. DF decay kinetics of D. tertiolecta differed among the cells growing in various nutrient conditions, indicating changes in the photosynthesis physiology.
authors.affiliation: Institute of Physical Biology, Veliko Mlacevo 59, SI-1290 Grosuplje, Slovenia.
authors.forename: Maja
authors.initials: M
authors.lastname: Berden-Zrimec
authors.affiliation: Institute of Physical Biology, Veliko Mlacevo 59, SI-1290 Grosuplje, Slovenia.
authors.forename: Luka
authors.initials: L
authors.lastname: Drinovec
authors.affiliation: Department of Biology, University of Trieste, v. Valerio 28/1, I-34127 Trieste, Italy.
authors.forename: Ilaria
authors.initials: I
authors.lastname: Molinari
authors.affiliation: Institute of Physical Biology, Veliko Mlacevo 59, SI-1290 Grosuplje, Slovenia.
authors.forename: Alexis
authors.initials: A
authors.lastname: Zrimec
authors.affiliation: Department of Biology, University of Trieste, v. Valerio 28/1, I-34127 Trieste, Italy.
authors.forename: Serena Fonda
authors.initials: SF
authors.lastname: Umani
authors.affiliation: OGS, Dipartimento di Oceanografia Biologica, Via Auguste Piccard 54, I-34010 Trieste, Italy.
authors.forename: Marina
authors.initials: M
authors.lastname: Monti
mesh_terms: D018533:Biomass; D002734:Chlorophyll / Q000032:analysis* / Q000302:isolation & purification; D000460:Chlorophyta / Q000254:growth & development / Q000502:physiology*; D005453:Fluorescence; D005470:Fluorometry; D007700:Kinetics; D010788:Photosynthesis
chemical_list: D002734:Chlorophyll