Shotgun lipidomics and mass spectrometry imaging unveil diversity and dynamics in Gammarus fossarum lipid composition

Sentinel species are playing an indispensable role in monitoring environmental pollution in aquatic ecosystems. Many pollutants found in water prove to be endocrine disrupting chemicals that could cause disruptions in lipid homeostasis in aquatic species. A comprehensive profiling of the lipidome of these species is thus an essential step toward understanding the mechanism of toxicity induced by pollutants. Both the composition and spatial distribution of lipids in freshwater crustacean Gammarus fossarum were extensively examined herein. The baseline lipidome of gammarids of different sex and reproductive stages was established by high throughput shotgun lipidomics. Spatial lipid mapping by high resolution mass spectrometry imaging led to the discovery of sulfate-based lipids in hepato-pancreas and their accumulation in mature oocytes. A diverse and dynamic lipid composition in G. fossarum was uncovered, which deepens our understanding of the biochemical changes during development and which could serve as a reference for future ecotoxicological studies.Approches Protéomique et Lipidomique pour la compréhension des mécanismes moléculaires de toxicité en lien avec l'altération du métabolisme lipidique chez l'espèce sentinelle Gammarus fossarum durant le cycle de reproductio

Phenotypic defects in Gammarus fossarum exposed to fenoxycarb as embryo

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Exposure of juvenile Danio rerio to aged TiO2 nanomaterial from sunscreen

International audienceThe toxicity of dietary exposure to artificially aged TiO2 nanomaterial (T-Lite (TM)) used in sunscreen cream was studied on Danio rerio. Embryolarval assays were conducted to assess the effects of TiO2 residues of nanomaterial (RNM) on fish early life stages. Juvenile fishes were exposed by the trophic route in two experiments. During the first experiment, juvenile fishes were exposed to TiO2 RNM for 14 days by adding RNM to commercial fish food. The second one consisted in producing a trophic food chain. Pseudokirchneriella subcapitata algae, previously contaminated with TiO2 RNM in growth medium, was used to feed Daphnia magna neonates over a 48-h period. Daphnia were used next to feed juvenile fishes for 7 days. Accumulation of Ti, life traits (survival and growth) and biochemical parameters such as energy reserves, digestive (trypsin, esterase, cellulose and amylase) and antioxidant (superoxide dismutase and catalase) enzyme activity were measured at the end of exposures. As expected in the receiving aquatic system, TiO2 RNM at low concentrations caused a low impact on juvenile zebrafish. A slight impact on the early life stage of zebrafish with premature hatching was observed, and this effect appeared mainly indirect, due to possible embryo hypoxia. When juvenile fish are exposed to contaminated food, digestive enzyme activity indicated a negative effect of TiO2 RNM. Digestive physiology was altered after 14 days of exposure and seemed to be an indirect target of TiO2 RNM when provided by food

Gammarus fossarum as a sensitive tool to reveal residual toxicity of treated wastewater effluents

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Fenoxycarb exposure disrupted the reproductive success of the amphipod <i>Gammarus fossarum</i> with limited effects on the lipid profile

<div><p>Insect growth regulator insecticides mimic the action of hormones on the growth and development of insect pests. However, they can affect the development of non-target arthropods. In the present study, we tested the effects of the growth regulator insecticide fenoxycarb on several endpoints in the freshwater crustacean <i>Gammarus fossarum</i> (Amphipoda). Females carrying embryos in their open brood pouch were exposed to 50 μg L^-1 fenoxycarb throughout the entire oogenesis (i.e. 21 days). After exposure, newborn individuals from exposed embryos were removed from the maternal open brood pouch for lipidomic analysis, while males were added to assess the reproductive success. After fertilization, the lipid profile, energy reserve content (lipids, proteins and glycogen), and activity of phenoloxidase − an enzyme involved in the immune response − were measured in females. No significant effect of fenoxycarb exposure was observed on the lipid profile of both newborn individuals and females, while reproductive success was severely impaired in exposed females. Particularly, precopulatory behavior was significantly reduced and fertilized eggs were unviable. This study highlighted the deleterious effects of the insect growth regulator fenoxycarb on gammarid reproduction, which could have severe repercussions on population dynamics.</p></div

Life-history traits in <i>G</i>. <i>fossarum</i> exposed to 50 μg L^-1 fenoxycarb.

<p>Mean±standard deviation. In parentheses, number of individuals or pooled sample analyzed.</p

Observation of lipid droplets in newborns.

<p>Newborn individual observed under a stereomicroscope (A), newborn individual observed with a fluorescence microscope after Nile red staining (lipid droplets are concentrated into the hepatopancreas) (B) and fluorescent area in the two study conditions (20 individuals/condition) (C).</p

Biochemical markers in control group and in the 50 μg L^-1 fenoxycarb-exposed group.

<p>Phenoloxidase activity (A), lipid content (B), protein content (C) and glycogen content (D). Ten females and 15 females were analyzed in the control and fenoxycarb-exposed groups, respectively.</p

Experimental design and measured endpoints in <i>G</i>. <i>fossarum</i> exposed to 50 μg L^-1 fenoxycarb.

<p>Experimental design and measured endpoints in <i>G</i>. <i>fossarum</i> exposed to 50 μg L^-1 fenoxycarb.</p