Molecular Evidence of the Toxic Effects of Diatom Diets on Gene Expression Patterns in Copepods

Diatoms are dominant photosynthetic organisms in the world's oceans and are considered essential in the transfer of energy through marine food chains. However, these unicellular plants at times produce secondary metabolites such as polyunsaturated aldehydes and other products deriving from the oxidation of fatty acids that are collectively termed oxylipins. These cytotoxic compounds are responsible for growth inhibition and teratogenic activity, potentially sabotaging future generations of grazers by inducing poor recruitment in marine organisms such as crustacean copepods.Here we show that two days of feeding on a strong oxylipin-producing diatom (Skeletonema marinoi) is sufficient to inhibit a series of genes involved in aldehyde detoxification, apoptosis, cytoskeleton structure and stress response in the copepod Calanus helgolandicus. Of the 18 transcripts analyzed by RT-qPCR at least 50% were strongly down-regulated (aldehyde dehydrogenase 9, 8 and 6, cellular apoptosis susceptibility and inhibitor of apoptosis IAP proteins, heat shock protein 40, alpha- and beta-tubulins) compared to animals fed on a weak oxylipin-producing diet (Chaetoceros socialis) which showed no changes in gene expression profiles.Our results provide molecular evidence of the toxic effects of strong oxylipin-producing diatoms on grazers, showing that primary defense systems that should be activated to protect copepods against toxic algae can be inhibited. On the other hand other classical detoxification genes (glutathione S-transferase, superoxide dismutase, catalase, cytochrome P450) were not affected possibly due to short exposure times. Given the importance of diatom blooms in nutrient-rich aquatic environments these results offer a plausible explanation for the inefficient use of a potentially valuable food resource, the spring diatom bloom, by some copepod species

Aufbau eines handlungsorientierten Dokumentations- und Informationssystems zur Anwendung arbeitswissenschaftlicher Erkenntnisse und Erfahrungen aus Projekten zur Humanisierung der Arbeitswelt fuer Unternehmen und Verbaende Endbericht. Berichtszeitraum: 1.7.1980-30.9.1984

In cooperation with Institut der Deutschen Wirtschaft, Forschungsgruppe PRODIS - Humanisierung der Arbeitswelt, Koeln (DE). Hauptabteilung 1: Bildung und GesellschaftswissenschaftenTIB: AC 9559 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Equilibrium Sampling of Hydrophobic Organic Contaminants in Sediments

Passive samplers are useful novel tools for assessing contaminant exposure and evaluating its potential for adverse environmental effects. Passive equilibrium samplers enable the quantification of freely dissolved concentrations (Cfree) of organic contaminants in sediments. Cfree allows a direct assessment of (1) contaminant exchange and equilibrium status between sediment and overlying water, (2) benthic bioaccumulation, and (3) potential toxicity to benthic organisms. Thus, the use of equilibrium samplers improves the mechanistic understanding of fate and transport processes in sediments. Equilibrium samplers can be applied for hazard and risk assessment and management of contaminated sediments of aquatic environments. The objective of this chapter is to provide introductory guidance on the use of passive equilibrium samplers for sediments contaminated with hydrophobic organic contaminants, whereby three different approaches are recommended: (1) silicone-coated glass jars, (2) SPME fibers that can be used ex situ with sediments that had been sampled in the field, and (3) SPME fibers that can be exposed directly in the field (in situ) when they are installed in a protective housing that is buried in the sediment. After reading this chapter, users will have a fundamental understanding of equilibrium passive samplers and their potential applications to sediments