Modulation of lipid biosynthesis by stress in diatoms

Diatoms are responsible for up to 40% of the carbon fixation in our oceans. The fixed carbon is moved through carbon metabolism towards the synthesis of organic molecules that are consumed through interlocking foodwebs, and this process is strongly impacted by the abiotic environment. However, it has become evident that diatoms can be used as ‘platform’ organisms for the production of high valuable bio-products such as lipids, pigments and carbohydrates where stress conditions can be used to direct carbon metabolism towards the commercial production of these compounds. In the first section of this review, some aspects of carbon metabolism in diatoms and how it is impacted by environmental factors are briefly described. The second section is focused on the biosynthesis of lipids and in particular omega-3 long-chain polyunsaturated fatty acids and how low temperature stress impacts on the production of these compounds. In a third section, we review the recent advances in bioengineering for lipid production. Finally, we discuss new perspectives for designing strains for the sustainable production of high-value lipids

The reward gap in hierarchical loyalty programmes: how to enhance bottom-tier customers’ loyalty without alienating top-tier customers

International audienceReward gap is the difference in the number and nature of rewards allocated to specific customer groups (or tiers) in a hierarchical loyalty programme. Building on the social comparison, equity and attribution theories, and two experiments conducted in a retailing context, we investigate the effect of reward gap size and visibility on both bottom-tier (BT) and top-tier (TT) customers. Findings from Study 1 show that a large reward gap reduces loyalty to the programme in BT customers, while it enhances it in TT customers. These effects are mediated by perceived fairness and perceived control. Findings from Study 2 show that a non-visible large reward gap increases loyalty to the programme in BT customers without affecting it in TT customers. This effect is mediated only by perceived fairness. Altogether, the findings highlight the mechanisms that explain the effect of the reward gap on BT and TT customers’ loyalty to the programme

The polyunsaturated fatty acids from microalgae as potential sources for health and disease

International audienceIn the classification of the plant kingdom, the microalgae occupy a particular place from their geographical localization, their behavior with respect to the environmental constraints but also from their morphology, their physiology and their biochemistry. These various aspects make their cellular machineries very flexible and able to produce many organic molecules with various biological activities such as proteins, polysaccharides, pigments and lipids of interest. With regard to the lipids, microalgae are able to produce many varieties and great amounts of fatty acids, especially of polyunsaturated fatty acids, making them candidates of interest within the framework of the production and exploitation of lipids in various sectors of industry and health. These fatty acids present in the lipids produced by microalgae can be used alike manner as those resulting from marine sources of animal origin such as fish in the field from health. The aims of this chapter are to present the biochemical diversity of the lipids and the fatty acids contained in various species of microalgae of marine and freshwater environments. Then, this review will give examples of how these plant resources can represent an alternative to the animal ones, particularly fish, in the area of the prevention of pathologies such as cardiovascular diseases and cancers

Use of radiolabeled substrates to determine the desaturase and elongase activities involved in eicosapentaenoic acid and docosahexaenoic acid biosynthesis in the marine microalga Pavlova lutheri

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Light Intensity Regulates LC-PUFA Incorporation into Lipids of Pavlova lutheri and the Final Desaturase and Elongase Activities Involved in Their Biosynthesis

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Light-dependent utilization of two radiolabelled carbon sources, sodium bicarbonate and sodium acetate, and relationships with long chain polyunsaturated fatty acid synthesis in the microalga Pavlova lutheri (Haptophyta)

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Combined effects of irradiance level and carbon source on fatty acid and lipid class composition in the microalga Pavlova lutheri commonly used in mariculture

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Proximate Analysis, Lipid Profile, Microbiological and Pigment Characterization of Chlorella Dry Powder Produced in a 20 L Agitated Photobioreactor

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ENVIRONMENTAL FACTORS AFFECTING GROWTH AND OMEGA 3 FATTY ACID COMPOSITION IN SKELETONEMA COSTATUM. THE INFLUENCES OF IRRADIANCE AND CARBON SOURCE

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Fatty acids profile and temperature in the cultured marine diatom Odontella aurita

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