Accumulation and detoxication responses of the gastropod Lymnaea stagnalis to single and combined exposures to natural (cyanobacteria) and anthropogenic (the herbicide RoundUp® Flash) stressors.

Freshwater gastropods are increasingly exposed to multiple stressors in the field such as the herbicide glyphosate in Roundup formulations and cyanobacterial blooms either producing or not producing microcystins (MCs), potentially leading to interacting effects. Here, the responses of Lymnaea stagnalis to a 21-day exposure to non-MC or MC-producing (33μgL−1) Planktothrix agardhii alone or in combination with the commercial formulation RoundUp®Flash at a concentration of 1μgL−1glyphosate, followed by 14days of depuration, were studied via i) accumulation of free and bound MCs in tissues, and ii) activities of anti-oxidant (catalase CAT) and biotransformation (glutathione-S-transferase GST) enzymes. During the intoxication, the cyanobacterial exposure induced an early increase of CAT activity, independently of the MC content, probably related to the production of secondary cyanobacterial metabolites. The GST activity was induced by RoundUp®Flash alone or in combination with non MC-producing cyanobacteria, but was inhibited by MC-producing cyanobacteria with or without RoundUp®Flash. Moreover, MC accumulation in L. stagnalis was 3.2 times increased when snails were concomitantly exposed to MC-producing cyanobacteria with RoundUp®, suggesting interacting effects of MCs on biotransformation processes. The potent inhibition of detoxication systems by MCs and RoundUp®Flash was reversible during the depuration, during which CAT and GST activities were significantly higher in snails previously exposed to MC-producing cyanobacteria with or without RoundUp®Flash than in other conditions, probably related to the oxidative stress caused by accumulated MCs remaining in tissues

Proteomic response of Unio pictorum mussel to a mixture of glyphosate and microcystin

International audienc

Specific Proteomic Response of <i>Unio pictorum</i> Mussel to a Mixture of Glyphosate and Microcystin-LR

Cyanobacterial toxins and pesticides regularly impact freshwaters. Microcystin-LR is one of the most toxic and common cyanobacterial toxins whereas glyphosate is the active ingredient of a widely use herbicide. As filter feeders, freshwater mussels are particularly exposed. Like many native bivalve species, <i>Unio pictorum</i> suffers from a continuous decline in Europe. In order to get a deeper insight of its response to contaminants, <i>U. pictorum</i> was exposed to either 10 μg L^–1 of microcystin-LR or 10 μg L^–1 of glyphosate or a mixture of both. Proteins of the digestive glands were extracted and analyzed by DIGE. Gel analysis revealed 103 spots with statistical variations, and the response seems to be less toward glyphosate than to microcystin-LR. Specific spots have variations only when exposed to the mixture, showing that there is an interaction of both contaminants in the responses triggered. The proteins of 30 spots have been identified. They belong mostly to the cytoskeleton family, but proteins of the oxidative pathway, detoxification, and energetic metabolism were affected either by glyphosate or microcystin-LR or by the mixture. These results demonstrate the importance to study contaminants at low concentrations representative of those found in the field and that multicontaminations can lead to different response pathways

Specific Proteomic Response of <i>Unio pictorum</i> Mussel to a Mixture of Glyphosate and Microcystin-LR

Cyanobacterial toxins and pesticides regularly impact freshwaters. Microcystin-LR is one of the most toxic and common cyanobacterial toxins whereas glyphosate is the active ingredient of a widely use herbicide. As filter feeders, freshwater mussels are particularly exposed. Like many native bivalve species, <i>Unio pictorum</i> suffers from a continuous decline in Europe. In order to get a deeper insight of its response to contaminants, <i>U. pictorum</i> was exposed to either 10 μg L^–1 of microcystin-LR or 10 μg L^–1 of glyphosate or a mixture of both. Proteins of the digestive glands were extracted and analyzed by DIGE. Gel analysis revealed 103 spots with statistical variations, and the response seems to be less toward glyphosate than to microcystin-LR. Specific spots have variations only when exposed to the mixture, showing that there is an interaction of both contaminants in the responses triggered. The proteins of 30 spots have been identified. They belong mostly to the cytoskeleton family, but proteins of the oxidative pathway, detoxification, and energetic metabolism were affected either by glyphosate or microcystin-LR or by the mixture. These results demonstrate the importance to study contaminants at low concentrations representative of those found in the field and that multicontaminations can lead to different response pathways