A screening strategy based on two zebrafish eleuthero-embryo OECD test guidelines for the hazard assessment of chemicals: case of some bisphenol substitutes

Christophe, A.; Piccini, B.; Hinfray, N.; Chadili, E.; Maillot-Marechal, E.; cousin, x.; Blanc, M.; Charlier, T.; Pandard, P.; Ait-Aissa, S.; Brion, F.

doi:10.1101/2023.06.16.545329

bioRxiv · 10.1101/2023.06.16.545329

A screening strategy based on two zebrafish eleuthero-embryo OECD test guidelines for the hazard assessment of chemicals: case of some bisphenol substitutes

Christophe, A.·Piccini, B.·Hinfray, N.·Chadili, E.·Maillot-Marechal, E.·cousin, x.·Blanc, M.·Charlier, T.·Pandard, P.·Ait-Aissa, S.·Brion, F.

View original source ↗Export metadata ↓

Abstract

The use of efficient screening strategies for the hazard assessment of chemicals is a current challenge to support regulatory requirements. Herein, we combined two eleuthero-embryo assays, a refined Fish Embryo Toxicity assay (OECD TG 236) and the EASZY assay (OECD TG 250), both using transgenic (tg) (cyp19a1b:GFP). The simultaneous performance of both assays provides complementary information about the acute toxicity, developmental effects, and estrogenic activity. A refined EASZY assay is however necessary to obtain accurate EC50. In this work we compared bisphenol A (BPA) and ten of its substitutes. In the refined FET, most of the selected bisphenols were more toxic than BPA, induced developmental effects on zebrafish embryos, some being identified as teratogenic compounds (BPF, BPS-MAE, BPC Cl, 4,4ODP), and ten of them induced GFP intensity. Endocrine activity of the BPs was further investigated in the EASZY assay at concentrations that do not affect the survival and the hatching rates or induce developmental toxicity based on the target concentrations used as previously defined in the refined FET. All bisphenols elicited an estrogenic activity with the notable exception of TCBPA. Most BPs were more estrogenic than BPA, acted as agonist ligands of zfER{beta}2 as shown in zebrafish-specific in vitro reporter gene assay and functional zfERs were required to induce brain aromatase. Interestingly, BPS-MAE and BPS-MPE behave as pro-estrogens as they were unable to transactivate zebrafish ER{beta}2 in vitro but induced brain aromatase in vivo. Overall, the implementation of the zebrafish eleuthero embryo-based screening strategy efficiently provided relevant data contributing to their environmental hazard. It also provides further evidence that bisphenols modulate cyp19a1b expression during early brain development whom potential short and long-term adverse effects need to be addressed. SYNOPSISa zebrafish eleuthero embryo-screening strategy based on OECD TGs was implemented for an efficient hazard assessment of bisphenols revealing that most of them are more toxic and/or estrogenic than BPA

Explore related subjects

pharmacology and toxicology Preprint

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

Christophe, A., Piccini, B., Hinfray, N., Chadili, E., Maillot-Marechal, E., cousin, x., Blanc, M., Charlier, T., Pandard, P., Ait-Aissa, S., Brion, F.. 2023-06-21. A screening strategy based on two zebrafish eleuthero-embryo OECD test guidelines for the hazard assessment of chemicals: case of some bisphenol substitutes. https://doi.org/10.1101/2023.06.16.545329

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

PCB-Exposed Gut Microbiota Recapitulate Neurobehavioral Deficits and Reprogram Hippocampal Transcriptomic Signatures

Polychlorinated biphenyls (PCBs) are persistent environmental pollutants associated with developmental neurotoxicity and autism spectrum disorder (ASD). However, whether PCB-induced alterations in gut microbiota contribute to neurodevelopmental toxicity independently of direct chemical exposure remains unclear. Here, we investigated whether transplantation of PCB-associated gut microbiota produces early neurobehavioral alterations and disrupts brain molecular pathways in offspring. Gut microbiota from conventional dams exposed to the Fox River PCB mixture (FRM; 6.0 mg/kg/day) or vehicle were transplanted into germ-free recipient females without direct PCB administration. At postnatal day 7 (P7), offspring underwent ultrasonic vocalization (USV) testing, whole-brain RNA sequencing (n = 4/sex/group), and untargeted serum metabolomics. Untargeted serum metabolomics were also performed in donor dams. PCB-associated fecal microbiota transplantation (FMT) significantly reduced offspring USVs, reproducing effects observed following direct maternal PCB exposure. Brain transcriptomics in offspring identified substantially more differentially expressed genes in males (9,339) than females (1,082), including 512 shared genes. Concordantly regulated genes revealed downregulation of neurotransmitter signaling and ion channel pathways alongside upregulation of RNA processing pathways. Male-associated responses involved altered protein synthesis and neuronal signaling, whereas female-associated responses involved DNA repair and extracellular matrix remodeling. Despite these molecular differences, behavioral responses showed no significant sex-dependent effect. Maternal metabolomics revealed increased bile acids and decreased indole-3-propionic acid, highlighting potential AhR-NF{kappa}B and bile acid-associated signaling mechanisms. Offspring metabolomics further identified alterations in lipid-associated metabolites and metabolic profiles. Collectively, these findings show that transferring PCB-exposed microbiota reproduces early neurobehavioral alterations and induces shared and sex-biased molecular responses, identifying the maternal gut microbiome as a candidate mediator linking PCB exposure to developmental neurotoxicity.

pharmacology and toxicology↗

bioRxiv2026

Cisplatin-triggered sensory dysfunction in NER-defective C. elegans involves GABAergic and cholinergic signaling

Cisplatin (CisPt) is a widely used anticancer drug that causes neurotoxicity as a dose-limiting adverse effect. DNA damage contributes to CisPt-induced neurotoxicity, yet the molecular mechanisms involved remain unclear. Here, we aim to identify pathophysiological mechanisms contributing to DNA damage-driven development of sensory neuronal dysfunction using the 3R-compliant model organism Caenorhabditis elegans. To this end, we employed the nucleotide excision repair (NER)-deficient ercc-1 mutant, which shows enhanced CisPt-induced sensory dysfunction as monitored by the chemotaxis assay, to elucidate drug-induced alterations in neurotransmission and transcriptome. We found that CisPt reduces gamma-aminobutyric acid (GABA) levels in the nematode and that GABA supplementation rescues ercc-1 mutants from CisPt-evoked sensory neurotoxicity, pointing to a neuroprotective function of GABA in the context of our study. Moreover, CisPt impairs the morphological integrity of GABAergic neurons particularly in ercc-1 mutants, which again is rescued by GABA substitution. Conversely, the cholinergic agonist carbachol impairs sensory function and exacerbates the neurotoxic effects of CisPt in ercc-1 mutants, indicating detrimental effects resulting from cholinergic excitation. Transcriptome analysis revealed that CisPt treatment stimulates a broard transcriptional response, including pathways involved in the regulation of neuronal communication, including acetylcholine-mediated neurotransmission, with pronounced effects occurring in the absence of ERCC-1. Based on these finding we suggest impaired GABAergic signaling and the loss of neuronal integrity GABAergic neurons as well as excessive cholinergic excitation as key mechanisms linking CisPt-induced DNA damage in NER defective nematodes to sensory dysfunction. Hence, targeting the balance between GABAergic inhibition and cholinergic excitation is suggested to counteract sensory neurotoxicity triggered by CisPt.

pharmacology and toxicology↗

bioRxiv2026

Mathematical model of phenotypic plasticity predicts interconversion is a drug target for neuroblastoma.

Neuroblastoma is a paediatric cancer arising from the sympathetic nervous system as neural crest cells, made up of noradrenergic (NOR/ADRN/N), mesenchymal like (MES/S), and intermediate (I-type/I) cell types. These cells can interconvert between types, contributing to treatment resistance and relapse. We developed a mathematical model to investigate how interconversion patterns affect the efficacy of phenotype-specific inhibitors. We used three ordinary differential equations to describe the dynamics of the three populations, including logistic growth, interconversion, and drug-induced death. Of the 64 possible interconversion patterns, five reduced the target population: two for N cells and three for S cells. N targeting patterns were more effective with higher interconversion rates, while mesenchymal targeting patterns were more effective with lower interconversion rates. Stability analysis revealed that natural tumour growth was always unstable, but during treatment, N-suppressing patterns combined with an S inhibitor gave the most consistently stable origin. Testing multi-stage and cyclic treatment schedules revealed that N-suppressing patterns with an S inhibitor, followed by an S-suppressing pattern with an N inhibitor, achieved more reliable remission. Three of the five patterns of interest correspond to reported biological plausibility, and known compounds exist to induce most of the required transitions, supporting the clinical relevance of these strategies for improving neuroblastoma treatment outcomes.

pharmacology and toxicology↗