Biology subjects

Derrien, A.

Publications and source records attributed to Derrien, A..

3 recordsLinked to original sources

bioRxiv2026

Influence of organs, body size and growth and domoic acid depuration in the king scallop, Pecten maximus.

Since 1995, European fisheries of Pecten maximus faced the presence of Pseudo-nitzschia species, which are able to produce the neurotoxin domoic acid responsible for Amnesic Shellfish Poisoning (ASP). As filter-feeders, scallops can accumulate and retain domoic acid much longer than most of the other bivalves, from months to years. When concentrations exceed the regulatory threshold, fisheries are closed leading to economic crisis. Inter-individual variability increases the difficulty to predict the depuration dynamics. Quantifying the correlations between domoic acid depuration in P. maximus and individual physiological traits, particularly body size, could improve the understanding of contamination and depuration. In this study, toxin dynamics in organs were analysed and the effects of body size and growth were assessed. This analysis was based on two datasets, one experimental and one in situ, of depuration monitoring of P. maximus exposed to a natural bloom of toxic P. australis. Results show that the distribuwtion of domoic acid shifted among organs between the contamination and after two months of depuration. Toxin concentrations negatively correlate with body size during contamination and after two months of depuration, but shift to a positive correlation after 7 months of depuration. This shift suggests that the smaller scallops accumulate more domoic acid and depurate it faster. Thus, dilution by growth can explain the reversal of the correlation between domoic acid and body size throughout depuration. These results yield useful information for modelling such mechanisms, providing valuable tools for scallop fishery management facing ASP. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=60 SRC="FIGDIR/small/708139v3_ufig1.gif" ALT="Figure 1"> View larger version (16K): org.highwire.dtl.DTLVardef@10e61deorg.highwire.dtl.DTLVardef@13b44b9org.highwire.dtl.DTLVardef@1cdba6org.highwire.dtl.DTLVardef@989861_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LIExperimental and in situ datasets allowed to quantify DA proportion dynamics in organs of P. maximus C_LIO_LIDA concentration and body size are negatively correlated during contamination phase, but positively correlated after a 7-month depuration C_LIO_LIConsidering dilution by growth is important for young scallops to assess DA depuration dy-namics C_LIO_LIBoth depuration rate and dilution by growth need to be considered to model DA depuration over the whole scallop size range C_LI

ecology↗

bioRxiv2025

H2AK119ub Safeguards Against Ectopic Transcription Factor Mediated Gene Activation in the Developing Forebrain

The PRC1 complex regulates developmental gene expression in mammals by ubiquitinating histones (H2AK119ub) and nucleating repressive chromatin interactions. Human genetic data and functional experimentation have demonstrated that H2AK119ub is required for cortical development, however the molecular mechanism for this remains unknown. Here, we show that mouse embryos expressing catalytically deficient RING1B exhibit intact early neurogenesis but display impaired neuroectodermal fate restriction. Using in vivo, primary, and in vitro models, we demonstrate that reduced H2AK119ub leads to ectopic activation of lineage-inappropriate transcriptional programmes, including mesodermal and endodermal gene expression during neural differentiation. This transcriptional deregulation is not solely attributable to H2AK119ub or H3K27me3 loss but instead reflects sensitisation of PRC1 target genes to inappropriate transcription factor (TF)-mediated activation. Synthetic induction of candidate TFs, including GATA6, SOX7, and SNAI1, phenocopies the fate-skewing effects of PRC1 catalytic dysfunction, confirming their causal role. Our results uncover a buffering role for PRC1-catalysed H2AK119ub in safeguarding neural progenitor identity by preventing inappropriate TF-driven transcription and provides a mechanistic framework for understanding the cellular heterogeneity and phenotypic variability observed in Polycomb-associated neurodevelopmental disorders.

molecular biology↗

bioRxiv2025

A 20-years comparative study of domoic acid depuration in king scallops, Pecten maximus, across French provinces.

Harmful Algal Blooms (HABs) can lead to fishery closures when toxin levels in commercial species exceed regulatory thresholds. Domoic acid (DA), the neurotoxin causing Amnesic Shellfish Poisoning (ASP), is particularly persistent in king scallops (Pecten maximus), a commercially valuable species in France. This species is known for its slow depuration rate compared to other species. As a result, anticipating DA dynamics is therefore a key to managing fishery openings in autumn, especially following spring contamination events. This study used 20 years of data from the French phycotoxin in-situ monitoring programme (REPHYTOX) to identify contamination events along the French Atlantic and English Channel coastlines. Depuration rates were estimated for 104 events; however, no correlation was found between depuration rate and province, time period, initial DA concentration or environmental conditions. Consequently, a median depuration rate was defined and applied in a widely used exponential decay model. In response to professionals needs, we developed a user-friendly predictive tool that estimates DA concentrations in king scallops based on sampling in spring or summer. We recommend performing DA quantification in scallops whenever DA is detected in other shellfish at the same location, and running the predictive model to anticipate DA content at the opening of the fishery season in autumn. This tool will help fishery managers to anticipate bans, to avoid unnecessary licence purchases, or to shift to alternative species. While developed using French data, the methodology is adaptable to other regions, with appropriate adjustments to reflect local ecological, regulatory and fishery contexts.

ecology↗