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Section: Ecotoxicology & Environmental Chemistry ; Topics: Environmental sciences

Impact of chlordecone pollution on biodiversity: The blind spot of 15 years of public policy in the French West Indies

Sanchez, Wilfried; Pesce, Stéphane; Betoulle, Stéphane; Charles, Sandrine; Coeurdassier, Michaël; Coutellec, Marie-Agnès; Leboulanger, Christophe; Martin-Laurent, Fabrice; Mougin, Christian; Nelieu, Sylvie; Sucré, Elliott; Leenhardt, Sophie; Mamy, Laure

10.24072/pcjournal.634 - Peer Community Journal, Volume 5 (2025), article no. e114
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For many years, there has been an unprecedented decline in biodiversity on a global scale, triggered largely by the use of plant protection products. In this context, a collective scientific assessment was conducted to identify current consensus knowledge and further needs regarding the impacts of plant protection products on biodiversity and ecosystem services in France, including its overseas territories. A particular focus was placed on chlordecone, a highly persistent organochlorine insecticide used extensively in the French West Indies (FWI) for more than 20 years (1972-1993) to control the banana root borer, but also in Eastern Europe, the USA, South America and Africa for various uses. The FWI support biodiversity hotspots, with many endemic and endangered species, and include marine and terrestrial protected areas. Such an environmental context is therefore highly relevant for studying the links between chlordecone contamination and potential effects on biodiversity. Thus, the objective of this work was to review the contamination of the FWI environment by chlordecone, its transfer through ecosystems, and its effects on biodiversity and ecosystem services. Literature analysis emphasized valuable knowledge of chlordecone ecodynamics in terrestrial, freshwater, and marine ecosystems. A wide diversity of terrestrial and aquatic organisms is chronically exposed to chlordecone. However, despite 15 years of public policy dedicated to developing knowledge on chlordecone’s fate and impacts, the knowledge gap remains critical regarding its effects on biodiversity and on ecosystem services. As the local environment is often contaminated for tens or even hundreds of years, future research is needed to characterize the effects of legacy pollution by chlordecone and its transformation products on organisms and ecosystems.
Section: Neuroscience ; Topics: Psychological and cognitive sciences, Health sciences, Neuroscience

Brain on Pause: How Sedentary Behavior Impacts Inhibitory Control Across Life

Lebon, Florent; Bertrand, Mathilde Fiona; Genand, Boris; Mourey, France; Ruffino, Célia; Papaxanthis, Charalambos; Gaveau, Jeremie; Rozand, Vianney

10.24072/pcjournal.638 - Peer Community Journal, Volume 5 (2025), article no. e113
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Inhibitory control, an important marker of daily-life autonomy, is impaired with age. However, the role of the level of physical activity (PA) and sedentary behavior (SB) in the lifelong decline of such cognitive-motor function remains to be elucidated. In the current study, we probed the association between inhibitory control and three predictors: age, PA and SB, by means of multiple regressions. Seventy-eight individuals, aged 18-88 years old, performed the Go-NoGo and Stop-Signal tasks to estimate motor impulse control and reactive inhibition, respectively. We measured the level of SB and PA during 4 consecutive days using accelerometers. Our main finding is that SB, but not PA, predicted reactive inhibition, similarly to age. In other words, a very old person with low SB would be more likely to stop an action than a younger person with higher SB. Our data suggest that achieving the recommended level of PA may not mitigate the association between low inhibitory function and high SB.
Section: Health & Movement Sciences ; Topics: Physiology, Psychological and cognitive sciences, Neuroscience

Superficial layers in M1 and beyond: Neural evidence of cortical and spinal activation during imagined movements

Lebon, Florent; Neige, Cecilia

10.24072/pcjournal.639 - Peer Community Journal, Volume 5 (2025), article no. e112
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Motor imagery is the mental simulation of an action without any overt movement, but shares common neural substrates with motor execution. In particular, the involvement of the primary motor cortex (M1) has been debated, and recently, Persichetti et al. (2020) probed, in an elegant experiment, the activation of different cortical layers within the hand-knob M1 area, during actual and imagined movements. By means of the vascular space occupancy technique, they achieved sub-millimeter spatial specificity without the vasculature bias of the BOLD signal. The main finding was that imagined finger movements activated only the superficial layers II/III with mainly cortico-cortical connections to M1, whereas actual finger movements activated both superficial layers and the deeper layers Vb/VI with descending corticospinal projections. This would nicely explain the absence of muscle activity during motor imagery. However, this exclusive activation of superficial layers in M1 during motor imagery is at odds with numerous observations in the current literature. In this opinion letter, we present several studies with different methodological approaches that found neural modulation downstream the pyramidal cells while imagining. These modulations following motor imagery practice, besides the changes within M1, would also explain improvement in motor learning. We also discussed the results by Persichetti et al. in regards of their protocol.
Section: Evolutionary Biology ; Topics: Evolution, Genetics/genomics, Microbiology

Comparative genomics of Rickettsiella bacteria reveal variable metabolic pathways potentially involved in symbiotic interactions with arthropods

Floriano, Anna M.; El-Filali, Adil; Amoros, Julien; Buysse, Marie; Jourdan-Pineau, Hélène; Sprong, Hein; Kohl, Robert; Dirks, Ron P.; Schaap, Peter; Koehorst, Jasper; Nijsse, Bart; Bouchon, Didier; Daubin, Vincent; Vavre, Fabrice; Duron, Olivier

10.24072/pcjournal.633 - Peer Community Journal, Volume 5 (2025), article no. e111
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Members of the Rickettsiella genus (order: Legionellales) are emerging as widespread bacteria associated with insects, arachnids, and crustaceans. While some Rickettsiella strains are highly virulent pathogens, others are maternally inherited endosymbionts that manipulate arthropod phenotypes, including the induction of defensive symbiosis and cytoplasmic incompatibility. However, the genomic diversity of Rickettsiella remains largely unexplored, and their genetic potential to induce complex phenotypes in arthropods is only partially understood. In this study, we sequenced five new Rickettsiella genomes isolated from three tick species. Through comparative genomics, we observed that Rickettsiella members share similar metabolic capabilities, and collectively lack virulence genes from pathogenic Legionellales. Additional analysis of Rickettsiella genomes revealed significant variability in metabolic properties related to endosymbiosis. Specifically, their capacity to biosynthesize certain B vitamins and heme varies, suggesting a functional role of some Rickettsiella strains in the nutrition of their arthropod hosts. Some Rickettsiella genomes harbour homologs of Wolbachia cif genes, the cause of Wolbachia-induced cytoplasmic incompatibility, suggesting that Rickettsiella may use a similar molecular mechanism to manipulate the reproduction of their arthropod hosts. Phylogenomics further revealed that tick-borne Rickettsiella exhibit distinct evolutionary origins within the genus, indicating that Rickettsiella have undergone repeated horizontal transfers between ticks and other arthropods.

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The network image was drawn by Martin Grandjean: A force-based network visualization CC BY-SA