Biology subjects

Blondeau-Bidet, E.

Publications and source records attributed to Blondeau-Bidet, E..

4 recordsLinked to original sources

bioRxiv2026

Genome-Environment Associations reveal shared and unique adaptive loci across multiple pollutants and populations of the eastern mosquitofish Gambusia holbrooki

Rapid adaptation to human-induced stressors is commonplace in the context of global change, including during biological invasions. Identifying the genomic bases and associated biological functions underlying such adaptation is hence crucial to understand and anticipate the response of populations and species to changing conditions. In particular, the extent to which genetic responses to multiple anthropogenic stressors vary between populations in the wild has been relatively unexplored. We addressed this question by leveraging whole-genome sequence data (both PoolSeq and IndSeq) in invasive populations of Gambusia holbrooki - a widespread invasive fish species - collected from 14 locations with different multi-pollutants exposure. We sought to identify adaptive loci associated with pollution tolerance by conducting Genome-Environment Association (GEA) analyses. Additionally, we investigated the degree of adaptive loci reuse between pollutants and their combinations as well as across populations. We found strong signals of association between allele frequency changes and pollutant exposure at several genomic locations, often overlapping with genes known for their functions in detoxification and immune response. We further showed that most adaptive loci are not shared among all populations, suggesting heterogeneous genomic response to each local selection. Interestingly, multiple tests looking for footprints of selection and association to pollutants yielded consistent results. Our results shed new light on the extent of genetic convergence in the genomic bases of rapid adaptation to different cocktails of human-induced pollution, and are important to our understanding of the fate of wild populations facing increasingly complex and stressful environments.

genomics↗

bioRxiv2025

Impact of port conditions and acclimation capacity of common two-banded seabream juveniles in the bay of Toulon: implications for nursery rehabilitation efforts

Ports are heavily anthropized coastal environments characterized by intense pollution and habitat alterations, creating challenging living conditions for marine organisms, particularly juvenile fish that rely on these areas as nurseries. While recent rehabilitation efforts of the nursery function in ports have focused on structural modifications, the impacts of port chemical and physical pollution are currently disregarded. Using field sampling and caging experiments, we examined the physiological (growth, lipid content, CYP1A-dependent biotransformation activity) and molecular (RNA-seq) responses of juvenile two-banded sea bream (Diplodus vulgaris) by comparing one port site with two adjacent sites from outside of the port, assessing their potential for short-term acclimation to port conditions. Results from individuals sampled in the field revealed distinct physiological and transcriptomic profiles in port juveniles, indicating specific responses to this environment. Notably, alterations related to lipid accumulation, detoxification, hypoxia, and circadian regulation were observed. After one month of caging all the individuals from different locations in the port, juveniles originating from outside the port exhibited stronger transcriptional responses compared to individuals that grew within the port, with higher expression of genes involved in detoxification and lipid metabolism, and a strong overexpression of oncogenes, while individuals originating from the port upregulated genes involved in energy metabolism, suggesting some capacity for short-term acclimation in port-resident juvenile fish. These findings highlight the potential impact of port conditions on juvenile fish health, with implications for the effectiveness of rehabilitation efforts. This study emphasizes the need for further research to inform nursery rehabilitation strategies in polluted ports.

physiology↗

bioRxiv2024

Identifying sexually dimorphic circulating microRNAs in gonochoristic and hermaphroditic marine fish species.

In many fish species, males and females are hard to distinguish at the juvenile stage and size differences appear during maturation, often favoring females. Molecular tools for sexing live fish would benefit aquaculture, fisheries, and conservation research. Here we aimed to explores to what extent circulating microRNAs (miRNAs) can decipher phenotypic males from phenotypic females in gonochoristic fish species (the European seabass Dicentrarchus labrax, the Turbot Scophthalmus maximus, the Red drum Sciaenops ocellatus, and the Blue Runner Caranx crysos) as well as sexual stages in a protandrous hermaphrodite species (the Gilthead seabream Sparus aurata). We collected and extracted total RNA from 258 plasma samples, of which 96 samples with satisfactory RNA quality were sequenced using small RNA-seq. Circulating miRNAs detected in the plasma allowed to easily discriminate species, but some miRNAs were significantly correlated to one sex, independently of the species. In immature fishes, 3 miRNAs: miR-21a-3p, miR-18a-3p, and miR-29-1a-5p were overexpressed in females compared to males, while in mature fish, miR-21a-3p exhibited an opposite pattern. In the Gilthead seabream, we detected that both the miR-21a-3p and the miR-125b-2/3-5p were likely involved in the sexual transition from male to female. A complementary analysis on the 3'UTR sequences of all fish species allowed to predict potential mRNA targets of those two miRNAs, some of them being particularly relevant regarding sexual development (i.e. wnt4, esrrb, esrrga and hsd17b1). The identification of miRNAs like miR-21a-3p and miR-125b-2/3-5p as potential sex markers could offer a new, poorly-invasive method to monitor sex and developmental stages in fishes.

molecular biology↗

bioRxiv2023

Circulating MicroRNAs indicative of sex and stress in the European seabass (Dicentrarchus labrax): toward the identification of new biomarkers.

MicroRNAs (miRNAs) constitute a new category of biomarkers. Studies on miRNAs in non-mammalian species have drastically increased in the last few years. Here, we explored the use of miRNAs as potential, poorly-invasive markers, to identify sex and characterize acute stress in fish. The European seabass (Dicentrarchus labrax) was chosen as model because of its rapid response to stress and its specific sex determination system, devoid of sexual chromosomes. We performed a small RNA-sequencing analysis in the blood plasma of males and females European seabass (mature and immature) as well as in the blood plasma of juveniles submitted to an acute stress and sampled throughout the recovery period (at 0h, 0.5h, 1.5h and 6h). In immature individuals, both miR-1388-3p and miR-7132a-5p were up-regulated in females, while miR-499a-5p was more abundant in males. However, no miRNAs were found to be differentially expressed between sexes in the blood plasma of mature individuals. For the acute stress analysis, five miRNAs (miR-155-5p, miR-200a-3p, miR-205-1-5p, miR-143-3p and miR-223-3p) followed cortisol production over time. All miRNAs identified were tested and validated by RT-qPCR on sequenced samples. A complementary analysis on the 3UTR sequences of the European seabass allowed to predict potential mRNA targets, some of them being particularly relevant regarding stress regulation, e.g. the glucocorticoid and the mineralocorticoid receptor. The present study provides new avenues and recommendations on the use of miRNAs as biomarkers of sex or stress of the European seabass, with potential application on other fish species.

physiology↗