Synnøve Liaaen-Jensen

Bio: Synnøve Liaaen-Jensen is an academic researcher from Norwegian University of Science and Technology. The author has contributed to research in topics: Carotenoid & Astaxanthin. The author has an hindex of 43, co-authored 358 publications receiving 7902 citations. Previous affiliations of Synnøve Liaaen-Jensen include Norwegian Institute of Technology.

Isolation and analysis

Abstract: This volume provides an introduction to the fundamental chemistry of carotenoid compounds, as well as detailed accounts of the basic methods used in carotenoid work. Part A covers the general methods of isolation and analysis.

[56] Quantitative determination of carotenoids in photosynthetic tissues

Abstract: Publisher Summary This chapter discusses the quantitative determination of carotenoids in photosynthetic tissues. A useful separation of carotenoid pigments into nonpolar carotenes and carotenoid esters in one group, and polar xanthophylls (containing hydroxyl groups) in the other may be accomplished by partitioning the pigments between petroleum ether and aqueous methanol. This can be done by dissolving the extract in aqueous methanol in a separatory funnel and adding an equal amount of petroleum ether. In cases where the carotenoid components are stable toward alkali, it is advantageous to include saponification in the isolation procedure for removing chlorophyll and other saponifiable matter. The pigment is taken to dryness (oil pump); all acetone must be removed from the extract to avoid base-catalyzed formation of condensation products of acetone. The residue is dissolved in a small volume of ether, and the same volume of 10% methanolic KOH solution is added. The approximate content of total carotenoids in an extract may be determined by measuring the optical density of a sample suitably diluted.

Plasma appearance and distribution of astaxanthin E/Z and R/S isomers in plasma lipoproteins of men after single dose administration of astaxanthin.

Abstract: Appearance, pharmacokinetics, and distribution of astaxanthin E/Z and R/S isomers in plasma and lipoprotein fractions were studied in 3 middle-aged male volunteers (37–43 years) after ingestion of a single meal containing a 100 mg dose of astaxanthin. The astaxanthin source consisted of 74% all- E -, 9% 9 Z -, 17% 13 Z -astaxanthin (3 R ,3′ R -, 3 R ,3′ S ; meso-, and 3 S ,3′ S -astaxanthin in a 1:2:1 ratio). The plasma astaxanthin concentration-–time curves were measured during 72 hr. Maximum levels of astaxanthin (1.3 ± 0.1 mg/L) were reached 6.7 ± 1.2 hr after administration, and the plasma astaxanthin elimination half-life was 21 ± 11 hr. 13 Z -Astaxanthin accumulated selectively, whereas the 3 and 3′ R/S astaxanthin distribution was similar to that of the experimental meal. Astaxanthin was present mainly in very low-density lipoproteins containing chylomicrons (VLDL/CM; 36–64% of total astaxanthin), whereas low-density lipoprotein (LDL) and high-density lipoprotein (HDL) contained 29% and 24% of total astaxanthin, respectively. The astaxanthin isomer distribution in plasma, VLDL/CM, LDL, and HDL was not affected by time. The results indicate that a selective process increases the relative proportion of astaxanthin Z -isomers compared to the all- E -astaxanthin during blood uptake and that astaxanthin E/Z isomers have similar pharmacokinetics.

Parasites, bright males, and the immunocompetence handicap

Abstract: It has been argued that females should be able to choose parasite-resistant mates on the basis of the quality of male secondary sexual characters and that such signals must be costly handicaps in order to evolve. To a large extent, handicap hypotheses have relied on energetic explanations for these costs. Here, we have presented a phenomenological model, operating on an intraspecific level, which views the cost of secondary sexual development from an endocrinological perspective. The primary androgenic hormone, testosterone, has a dualistic effect; it stimulates development of characteristics used in sexual selection while reducing immu- nocompetence. This "double-edged sword" creates a physiological trade-off that influences and is influenced by parasite burden. We propose a negative-feedback loop between signal intensity and parasite burden by suggesting that testosterone-dependent signal intensity is a plastic re- sponse. This response is modified in accordance with the competing demands of the potential costs of parasite infection versus that of increased reproductive success afforded by exaggerated signals. We clarify how this trade-off is intimately involved in the evolution of secondary sexual characteristics and how it may explain some of the equivocal empirical results that have surfaced in attempts to quantify parasite's effect on sexual selection.

Rhodopsin-like Protein from the Purple Membrane of Halobacterium halobium

Abstract: HALOPHILIC bacteria require high concentrations of sodium chloride and lower concentrations of KCl and MgCl2 for growth. The cell membrane dissociates into fragments of varying size when the salt is removed1. One characteristic fragment—termed the “purple membrane” because of its characteristic deep purple colour—has been isolated in relatively pure form from Halobacterium halobium2. We can now show that the purple colour is due to retinal bound to an opsin-like protein, the only protein present in this membrane fragment (see also ref. 3).

Biosynthesis of plant pigments: anthocyanins, betalains and carotenoids

Abstract: Plant compounds that are perceived by humans to have color are generally referred to as 'pigments'. Their varied structures and colors have long fascinated chemists and biologists, who have examined their chemical and physical properties, their mode of synthesis, and their physiological and ecological roles. Plant pigments also have a long history of use by humans. The major classes of plant pigments, with the exception of the chlorophylls, are reviewed here. Anthocyanins, a class of flavonoids derived ultimately from phenylalanine, are water-soluble, synthesized in the cytosol, and localized in vacuoles. They provide a wide range of colors ranging from orange/red to violet/blue. In addition to various modifications to their structures, their specific color also depends on co-pigments, metal ions and pH. They are widely distributed in the plant kingdom. The lipid-soluble, yellow-to-red carotenoids, a subclass of terpenoids, are also distributed ubiquitously in plants. They are synthesized in chloroplasts and are essential to the integrity of the photosynthetic apparatus. Betalains, also conferring yellow-to-red colors, are nitrogen-containing water-soluble compounds derived from tyrosine that are found only in a limited number of plant lineages. In contrast to anthocyanins and carotenoids, the biosynthetic pathway of betalains is only partially understood. All three classes of pigments act as visible signals to attract insects, birds and animals for pollination and seed dispersal. They also protect plants from damage caused by UV and visible light.