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Response of alpha-tocopherol and beta-carotene production in microalgae to temperature, salinity and photon flux density
Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Ecological Botany.
Department of Systems Ecology, Stockholm University.
Center of Excellence Evolutionary Genetics & Physiology, Department of Biology, Laboratory of Animal Physiology, University of Turku, Finland.
Department of Systems Ecology, Stockholm University.
(English)In: Journal of Applied Phycology, ISSN 0921-8971, E-ISSN 1573-5176Article in journal (Refereed) Submitted
Abstract [en]

Oxidative stress occurs in plant and animal cells in association with oxygen. Therefore non-enzymatic antioxidants, like α-tocopherol and β-carotene, are necessary in to prevent irreversible damages caused by reactive oxygen species. Most antioxidants or their precursors are plant-derived and any fluctuation in the synthesis of these substances will affect consumers directly. To study the effects of environmental factors on antioxidant production by microalgae, cultures of the microalgae Dunaliella tertiolecta (Chlorophyceae),  Nodularia spumigena (Cyanophyceae), Prorocentrum minimum Dinophyceae), Phaeodactylum tricornutum (Bacillariophyceae) , Skeletonema costatum (Mediophyceae) and Rhodomonas salina (Cryptophyceae) were incubated for 48 h at different photon flux densities, temperatures and salinities. The initial concentrations varied widely between the cultures (α-tocopherol: 0.03 – 0.52 mg g C-1; β-carotene: 0.11 – 2.72 mg g C-1). D. tertiolecta showed increased α-tocopherol content in response to increased photon flux density. The cultures of P. minimum, P. tricornutum and S. costatum showed an increase and N. spumigena a decrease of α-tocopherol concentration with increasing temperature.  Photon flux  density and temperature in combination were of significant importance only for the R. salina cultures. In N. spumigena and P. tricornutum cultures, α-tocopherol concentrations increased with increasing salinity and temperature, whereas in D. tertiolecta cultures the opposite was found. In P. minimum and S. costatum cultures, salinity did not influence α-tocopherol concentration significantly. β-carotene and α-tocopherol were positively associated with each other except in D. tertiolecta and P. tricornutum. Only in one of twelve cases associations between α-tocopherol / super oxide dismutase and β-carotene / super oxide dismutase were found. It can be concluded that besides species composition of phytoplankton communities, differences in temperature and salinity contribute to the variation in antioxidant synthesis. Thus consumers must be adapted to a varying antioxidant pool.

Keyword [en]
Vitamin E; Carotenoids; Phytoplankton; Oxidative stress
URN: urn:nbn:se:uu:diva-130138OAI: oai:DiVA.org:uu-130138DiVA: diva2:346641
Available from: 2010-09-02 Created: 2010-09-02 Last updated: 2011-01-10Bibliographically approved
In thesis
1. Dynamics of astaxanthin, tocopherol (Vitamin E) and thiamine (Vitamin B1) in the Baltic Sea ecosystem: Bottom-up effects in an aquatic food web
Open this publication in new window or tab >>Dynamics of astaxanthin, tocopherol (Vitamin E) and thiamine (Vitamin B1) in the Baltic Sea ecosystem: Bottom-up effects in an aquatic food web
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The thesis combines laboratory experiments and field expeditions to study production, transfer and consumption of non-enzymatic antioxidants and thiamine in an aquatic food web. In particular, I (1) documented spatial and seasonal variation of tocopherols and carotenoids in the Baltic Sea pelagic food web, and (2) examined the effects of abiotic and biotic factors on tocopherol, carotenoid and thiamine concentrations in phytoplankton, zooplankton and fish.

Moderate differences in temperature and salinity affected α-tocopherol, β-carotene and thiamine production in microalgae. Furthermore, the results suggest that acute stress favors the expression of non-enzymatic antioxidants rather than enzymatic antioxidants. Because production of α-tocopherol, β-carotene and thiamine differ markedly between microalgae, the availability of non-enzymatic antioxidants and thiamine is likely to be highly variable in the Baltic Sea and is difficult to predict.

The transfer of non-enzymatic antioxidants from phytoplankton to zooplankton was biomass dependent. The field expeditions revealed that phytoplankton biomass was negatively associated with α-tocopherol concentration in mesozooplankton. Thus, increased eutrophication of the Baltic Sea followed by an increase in phytoplankton biomass could decrease the transfer of essential biochemicals to higher levels in the pelagic food web. This could lead to deficiency syndromes, of the kind already observed in the Baltic Sea. Astaxanthin is synthesized from precursors provided by the phytoplankton community. Thus biomass dependent transfer of astaxanthin precursors from phytoplankton to zooplankton could be responsible for astaxanthin deficiency in zooplanktivorous herring. Astaxanthin in herring consists mostly of all-Z-isomers, which are characterized by low bioavailability. Therefore, astaxanthin deficiency in salmon could be explained by the low concentration of this substance and its isomeric composition in herring.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2010. 47 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 762
Baltic Sea, carotenoids, astaxanthin, tocopherols, Vitamin E, thiamine, Vitamin B1, pelagic food web, eutrophication, M74, phytoplankton, zooplankton, sprat, Sprattus sprattus balticus, herring, Clupea harengus, salmon, Salmo salar, cod, Gadus morhua, High Performance Liquid Chromatography (HPLC), electrochemical detection (ECD)
urn:nbn:se:uu:diva-130143 (URN)978-91-554-7878-0 (ISBN)
Public defence
2010-10-15, Lindahlsalen, Norbyvägen 18, EBC, Uppsala, 10:00 (English)
Available from: 2010-09-23 Created: 2010-09-02 Last updated: 2011-01-10

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