Uptake visualization of deltamethrin by NanoSIMS and acute toxicity to the water flea Daphnia magna.

The objective of this study was to investigate the uptake of deltamethrin, an insecticide, by Daphnia magna neonates by SIMS and to compare these findings with results based on established toxicity tests. Young daphnids (aged <24 h) were exposed to 0, 50 and 200 microg L(-1) (ppb) deltamethrin. Mobile, immobile and dead animals were enumerated after 24 and 48 h following OECD 202 [OECD 202, 2004. Daphnia sp., acute immobilisation test, guideline for testing of chemicals] guidelines. The animals were embedded in epoxy resin, cut into semi-thin sections (500 nm) and placed on silicon supporters. NanoSIMS 50 (Cameca) images were made from tissues of the intestine for carbon, nitrogen (measured as CN), phosphorus and bromine. To distinguish between relative concentrations of bromine in the guts from different exposure concentrations of deltamethrin, a carbon normalization method was carried out. Both deltamethrin concentrations and time showed a significant effect on immobilization and mortality of the daphnids (P<0.0001). Bromine from deltamethrin could be visualized by NanoSIMS in all exposed gut tissues (gut wall, microvilli layer, perithropic membrane). Highest deltamethrin concentrations following (12)C normalization were found in animals exposed to 200 microg L(-1) deltamethrin, followed by 50 microg L(-1) and the control. NanoSIMS 50 was successfully used as a supplemental technique for elucidating the relation between the uptake and localization of deltamethrin and its toxicity to D. magna. These results highlight the potential usefulness of NanoSIMS to detect marker elements of xenobiotic compounds within exposed organisms, to compare relative exposure concentrations, and to locate these compounds at their original tissue location.

NanoSIMS 50 elucidation of the natural element composition in structures of cyanobacteria and their exposure to halogen compounds.

AIMS: NanoSIMS (secondary ion mass spectrometry) is a powerful technique for mapping the elemental composition of a variety of small-scale samples (e.g. in Material Research, Cosmochemistry and Geology). However, its analytical features are making it also valuable to address biological questions. We demonstrate the ability of the NanoSIMS 50 to map elements at subcellular lateral resolution (approx. 50 nm) within cyanobacteria (Anabaena sp. and Cylindrospermum alatosporum) and its feasibility to investigate the uptake of bromine-containing substances (NaBr and deltamethrin). METHODS AND RESULTS: Elemental maps of O, N, P and S were obtained from semi-thin sections of different cell types (chemically fixed and resin-embedded heterocysts, akinetes and vegetative cells). NanoSIMS enabled the detection of various characteristic cell sub-structures and inclusions. A homogenous bromine distribution was detected following NaBr and deltamethrin exposure, at Br-concentrations of 0.05, 0.5 (NaBr) and 0.0025 mmol l(-1) (deltamethrin). CONCLUSIONS: NanoSIMS allowed study of the mapping of common elements in cyanobacterial cells and the uptake of NaBr and deltamethrin. SIGNIFICANCE AND IMPACT OF THE STUDY: These results highlight the potential usefulness of NanoSIMS analysis for tracking elements within cell structures at the nanoscale and the ability to detect marker elements of xenobiotic compounds within exposed organisms.