Enzymatic decontamination of paraoxon-ethyl limits long-term effects in planarians

Abstract

organophosphorus compounds (op) are highly toxic molecules used as insecticides that inhibit cholinesterase enzymes involved in neuronal transmission. the intensive use of op for vector control and agriculture has led to environmental pollutions responsible for severe intoxications and putative long-term effects on humans and wild animals. Many in vivo models were studied over the years to assess OP acute toxicity, but the long-term effects are poorly documented. Planarian, a freshwater flatworm having a cholinergic system, has emerged as a new original model for addressing both toxicity and developmental perturbations. We used Schmidtea mediterranea planarians to evaluate long-term effects of paraoxon-ethyl at two sublethal concentrations over three generations. Toxicity, developmental perturbations and disruption of behavior were rapidly observed and higher sensitivity to paraoxon-ethyl of next generations was noticed suggesting that low insecticide doses can induce transgenerational effects. With the view of limiting OP poisoning, Ssopox, an hyperthermostable enzyme issued from the archaea Saccharolobus solfataricus, was used to degrade paraoxon-ethyl prior to planarian exposure. The degradation products, although not lethal to the worms, were found to decrease cholinesterase activities for the last generation of planarians and to induce abnormalities albeit in lower proportion than insecticides.

Disrupting quorum sensing alters social interactions in Chromobacterium violaceum

“…To assess whether QS may contribute to C. violaceum competition with animals, we used an aquatic model organism, the freshwater flatworm Schmidtea mediterranea . In recent decades, planarians have emerged as relevant invertebrate models for toxicology and ecotoxicology studies and have been used to evaluate neurodegenerative diseases as well as the toxicity of environmental pollutants and neurotoxic chemicals 56 – 59 . Moreover, planarians have been previously described as particularly resistant to bacterial infections by eliminating bacteria mainly through phagocytosis 60 .…”

Mechanistic theory predicts the effects of temperature and humidity on inactivation of SARS-CoV-2 and other enveloped viruses

“…Smaller aerosols settle to the ground more slowly 8 Several analyses have projected that SARS-CoV-2 transmission will be faster in temperate winters (1,2,52), as occurs with other respiratory viruses (4). Major seasonal or climate-mediated e ects on SARS-CoV-2 epidemiology were not evident during the northern hemisphere's spring and summer (53,54); this was expected, since population susceptibility and epidemic control measures can be more important than seasonality in an early pandemic context (52). Thus the fact that temperate summers did not eliminate transmission should not lead to false confidence that temperate winters will not promote it.…”

Temporal dynamics for areal unit-based co-occurrence COVID-19 trajectories

“…Many mathematical and statistical models and methods have been applied to study the dynamics of COVID-19. Specifically, regression analysis was conducted for the effects of social and economic risk factors [13] , [22] , [27] , [33] , [40] , time-series models were utilized to deal with temporal dependency throughout the pandemic [25] , [5] and spatial models have been employed for understanding the diffusion of COVID-19 spread [10] . Other recent studies attempted to build efficient methods that incorporate both time and space effects in order to model COVID-19's dynamics [11] , [28] , [30] , [38] .…”