Darnaudery, M. | bioRxiv Science

bioRxiv2026

Distribution of antibiotic resistance genes across contrasted tropical agroecosystems in Reunion Island

This study presents the first exploratory assessment of antibiotic resistance genes (ARGs) and antibiotic residues in agricultural environments on Reunion Island, a French tropical territory in the south-western Indian Ocean. Sixteen samples from diverse matrices (manure, soil, water, and vegetables) across different agroecosystems were analyzed using high-throughput qPCR targeting 332 ARGs and chemical methods targeting 58 antibiotic compounds and trace elements. ARGs were widely detected across all matrices, with highest abundance observed in amended soils and manure. Surprisingly, ARG profiles, in terms of both abundance and average number, were comparable between unamended soils and natural soils. Antibiotic residues were found in only five manure and soil samples, with no clear correlation between the presence of these residues, trace elements and ARG abundance. Organic amendments significantly increased ARG levels in soils and non-metric multidimensional scaling revealed that ARG profiles clustered primarily by matrix type rather than by location. High-risk ARGs were widely prevalent, with 86% detected and 23% ubiquitous across all samples, and their occurrence in water and raw vegetables suggests potential human exposure through the food chain. This study highlights the influence of agricultural practices on environmental antimicrobial resistance in tropical island contexts and supports the need for expanded One Health surveillance integrating the environmental, animal and human compartments. SynopsisThis study shows that agricultural practices can shape the environmental spread of antibiotic resistance in tropical island ecosystems, highlighting potential risks for ecosystems, food safety, and human health. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=73 SRC="FIGDIR/small/702181v1_ufig1.gif" ALT="Figure 1"> View larger version (31K): org.highwire.dtl.DTLVardef@1d07b87org.highwire.dtl.DTLVardef@5e1150org.highwire.dtl.DTLVardef@1c2afe4org.highwire.dtl.DTLVardef@a9be55_HPS_FORMAT_FIGEXP M_FIG C_FIG

molecular biology↗

bioRxiv2023

Strain-specific changes in nucleus accumbens transcriptome and motivation for food reward in mice exposed to maternal separation

Adversity in childhood exerts enduring effects on brain and increases the vulnerability to psychiatric diseases. It also leads to a higher risk for eating disorders and obesity. We hypothesised that neonatal stress in mice affects motivation to obtain palatable food in adulthood and changes gene expression in reward system. Male and female pups from C57Bl/6J and C3H/HeN mice strains were subjected to a daily maternal separation (MS) protocol from PND2 to PND14. In adulthood, their motivation for palatable food reward was assessed in operant cages. Compared to control mice, male and female C3H/Hen mice exposed to MS significantly did more lever presses to obtain palatable food especially when the effort required to obtain the reward is high. Transcriptional analysis reveals 375 genes differentially expressed in the nucleus accumbens of male MS C3H/HeN mice compared to the control group, some of these being associated with the regulation of the reward system (e.g. Gnas, Pnoc). Interestingly, C57Bl/6J mice exposed to MS did not show any alteration in their motivation to obtain a palatable reward nor significant changes in gene expression in the nucleus accumbens. In conclusion, neonatal stress produces lasting changes in motivation for palatable food in C3H/HeN offspring but has no impact in C57Bl/6J offspring. These behavioural alterations are accompanied by drastic changes in gene expression specifically within the nucleus accumbens, a key structure in the regulation of motivational processes.

neuroscience↗