Brischoux, F. | bioRxiv Science

bioRxiv2025

Brain-blood biomarkers take a walk on the wild side: glial responses to environmental conditions and individual traits in wild frogs

Proteins from brain cells, including Glial fibrillary acidic protein (GFAP), has been tested for diagnostic and prognostic of neurological dysfunctions. Release of GFAP into the blood-stream, may be a consequence of its up-regulation in reactive astrocytes. However, astrocytic-GFAP expression is also increased during brain remodeling after physiological perturbations such as osmotic challenge. The presence and quantification of GFAP in blood circulation have never been investigated in the context of brain responses to environmental variations in wildlife. In a wild amphibian (green frogs, Pelophylax sp.), captured in several ponds with different salinity, GFAP was detected in plasma. Males from more saline ponds exhibited higher plasmatic GFAP levels, independent to their blood osmolality, suggesting that plasmatic GFAP-level reflects cerebral response to osmotic challenge. Plasmatic-GFAP correlated with immune markers (hemoglobin binding proteins, lymphocytes, neutrophils and monocytes), size and body condition, reinforcing its role as a physiological biomarker. We also highlighted that captivity had a significant effect on plasmatic-GFAP levels with sex-specific dynamics, masking the response to a short-term experimental salinity exposure. For the very first time, we show that plasmatic-GFAP levels could be a biomarker of brain plasticity to environmental conditions, physiological traits, and stress responses in wildlife. Significant StatementWe investigated the use of brain Glial fibrillary acidic protein (GFAP), a cytoskeletal protein of astrocytes, that has been associated with brain disorders in clinical studies, as a biomarker of environmental conditions and individual traits in wildlife. In a wild amphibian, plasmatic GFAP-levels were correlated with the salinity of ponds, immune markers and size for males. GFAP-levels were correlated with body condition for both sexes. Interestingly, captivity induced transient increase of plasmatic-GFAP levels, probably due to stress. In our study, we demonstrate that plasmatic-GFAP levels may represent an excellent brain biomarker of its plasticity to environmental conditions, physiological traits, and stress responses in wildlife.

physiology↗

bioRxiv2023

Maternal body condition affects the response of the gut microbiome to a widespread contaminant in larval spined toads

Glyphosates primary metabolite, aminomethylphosphonic acid (AMPA), is the most detected pollutant in surface waters. Recent studies have raised concerns about its toxicity, yet underlying mechanisms remain poorly understood. A disruption of the gut microbiome, which plays a crucial role in host health, could mediate most of the adverse effects. We investigated the impact of AMPA exposure on the gut microbiome of spined toad tadpoles (Bufo spinosus). We hypothesized that AMPA could alter the gut microbiota composition and that these effects could depend on the microbiota source. We exposed tadpoles to minute concentrations of AMPA and analyzed their faecal microbiota using 16S rRNA gene sequencing as a proxy of the gut microbiota. AMPA exposure decreased the gut bacterial biomass and affected the bacterial community composition of tadpoles faeces. Furthermore, we observed interactions between AMPA exposure and maternal body condition on the Bacteroidota and Actinobacteriota phyla abundances. This suggests a maternal effect on early-life microbial colonizers that could influence the response of the gut microbiome to AMPA. These findings highlight the importance of considering the gut microbiome when studying the effects of environmental contaminants. Further research is needed to elucidate the long-term implications of this microbiome alteration for amphibian health.

ecology↗