arXiv subjects

Arnaud Chaumot

Publications and source records attributed to Arnaud Chaumot.

3 recordsLinked to original sources

arXiv2025

Multivariate Functional Data Analysis Uncovers Behavioral Fingerprints in Invertebrate Locomotor Response to Micropollutants

The need for effective biomonitoring in wastewater has become clear due to the impracticality of continuously tracking all chemicals and emerging contaminants in the aquatic exposome. Effect-based biomonitoring provides a cost-effective solution. The ToxMate device, which uses videotracking of locomotor behavior in aquatic invertebrates, has proven efficient for real-time detection of micropollutant surges in effluents. To extend the approach, this proof-of-concept study evaluates the potential to formalize behavioral fingerprints from real-time videotracking data to characterize qualitative variations in effluent contamination. We present the first application of a functional data analysis (FDA) framework in ecotoxicology. Data were obtained by simultaneously tracking three sentinel organisms from distinct taxa (a crustacean, an annelid, and a gastropod) during pulse exposures to four chemicals in the laboratory (two metals, one pharmaceutical, and one insecticide). Individual and multispecies responses were analy-zed to determine whether combining species enhances the resolution of contamination fingerprints through multidimensional FDA. Applying the same data-driven approach to field data from a wastewater treatment plant (WWTP) revealed four recurring types of micropollution events. This proof of concept demonstrates the potential of behavioral fingerprints to improve wastewater monitoring and reduce pollutant transfer to the environment.

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arXiv2025

Rank Ordering of Species Sensitivities to Chemicals: Discrepancies between Behavioral and Lethal Responses in Freshwater and Marine Invertebrates

Locomotor behavioural responses are increasingly recognized as sensitive and ecologically relevant indicators for assessing aquatic organism exposure to contaminants. They often occur at concentrations lower than those causing physiological damage, yet their consequences for organisms' fitness and population dynamics remain unclear. Moreover, it is still uncertain how these behavioural endpoints align with traditional toxicological apical endpoints used to assess species sensitivities in risk assessment. This study evaluates the correlation between thresholds triggering locomotor reactions with LC50 values across 19 freshwater and 12 marine invertebrate species exposed to the insecticide imidacloprid and the metal copper. Behavioural responses were measured via videotracking during pulse exposure assays, while 96h acute tests provided species-specific LC50 values for copper. Results reveal strong discrepancies: some highly sensitive species showed no locomotor changes, whereas others tolerant to lethality displayed strong movement responses. For instance, freshwater annelids and gastropods responded markedly to imidacloprid, while marine shrimps exhibited hyperactivity under low copper levels. These findings indicate that relying solely on lethality-based data may underestimate the fraction of species affected by contamination. Integrating behavioural endpoints into population risk assessment frameworks is therefore crucial to better protect aquatic biodiversity.

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arXiv2008

Annotation of Tribolium nuclear receptors reveals an evolutionary overacceleration of a network controlling the ecdysone cascade

The Tribolium genome contains 21 nuclear receptors, representing all of the six known subfamilies. When compared to other species, this first complete set for a Coleoptera reveals a strong conservation of the number and identity of nuclear receptors in holometabolous insects. Two novelties are observed: the atypical NR0 gene knirps is present only in brachyceran flies, while the NR2E6 gene is found only in Tribolium and in Apis. Using a quantitative analysis of the evolutionary rate, we discovered that nuclear receptors could be divided into two groups. In one group of 13 proteins, the rates follow the trend of the Mecopterida genome-wide acceleration. In a second group of five nuclear receptors, all acting together at the top of the ecdysone cascade, we observed an overacceleration of the evolutionary rate during the early divergence of Mecopterida. We thus extended our analysis to the twelve classic ecdysone transcriptional regulators and found that six of them (ECR, USP, HR3, E75, HR4 and Kr-h1) underwent an overacceleration at the base of the Mecopterida lineage. By contrast, E74, E93, BR, HR39, FTZ-F1 and E78 do not show this divergence. We suggest that coevolution occurred within a network of regulators that control the ecdysone cascade. The advent of Tribolium as a powerful model should allow a better understanding of this evolution.

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