title: Age and nutrient limitation enhance polyunsaturated aldehyde production in marine diatoms.
abstract: Skeletonema marinoi produces 2,4-heptadienal, 2,4-octadienal, and 2,4,7-octatrienal, the latter only in traces. In nutrient-replete cultures, the production of potentially defensive polyunsaturated aldehydes (PUA) increases from the exponential to the stationary phase of growth from 1.2 fmol cell(-1) (+/-0.4 fmol cell(-1) SD) to 4.2 fmol cell(-1) (+/-1.0 fmol cell(-1) SD), with 2,4-heptadienal as the dominant aldehyde. The plasticity of PUA production with age of the culture supports the hypothesis of a direct link between toxin production and cell physiological state. N- and P-limited cells in stationary phase produced 1.4 and 1.8 fold higher amounts of PUA than control cultures and 10.7 and 4.6 times higher PUAs when compared to their own exponential growth phase, respectively. The increase in PUA production in the nutrient-limited cultures was not paralleled by an increase in the total amount of precursor fatty acids indicating that physiological stress might trigger an enhanced expression or activity of the enzymes responsible for PUA production, i.e. chemical defense increase in aged and nutrient-stressed diatoms. If this holds true during blooms, grazers feeding at the end of a bloom would be more affected than early-bloom grazers.
authors.affiliation: Stazione Zoologica Anton Dohrn di Napoli, Villa Comunale, I80121 Napoli, Italy.
authors.forename: François
authors.initials: F
authors.lastname: Ribalet
authors.forename: Thomas
authors.initials: T
authors.lastname: Wichard
authors.forename: Georg
authors.initials: G
authors.lastname: Pohnert
authors.forename: Adrianna
authors.initials: A
authors.lastname: Ianora
authors.forename: Antonio
authors.initials: A
authors.lastname: Miralto
authors.forename: Raffaella
authors.initials: R
authors.lastname: Casotti
mesh_terms: D000447:Aldehydes / Q000302:isolation & purification*; D017377:Diatoms / Q000254:growth & development* / Q000378:metabolism; D005231:Fatty Acids, Unsaturated / Q000302:isolation & purification*; D008386:Marine Biology; D009566:Nitrates / Q000378:metabolism; D010710:Phosphates / Q000378:metabolism; D013997:Time Factors
chemical_list: D000447:Aldehydes; D005231:Fatty Acids, Unsaturated; D009566:Nitrates; D010710:Phosphates