Circulating MicroRNAs Indicative of Sex and Stress in the European Seabass (Dicentrarchus labrax): Toward the Identification of New Biomarkers

Abstract

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 3'UTR 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.

Identification of sex-biased miRNA markers informative of heat-past events

“…Similarly, miR-143-3p and miR-92a-3p, which were downregulated in high temperature treated fish in the present study, were altered in mice testes exposed for only 25 minutes to elevated temperatures, highlighting them as potential markers in heat-induced spermatogenesis disorder (Gan et al, 2023). Higher levels of circulating miR-143 and miR-223 were detected in plasma levels together with cortisol after acute stress response in E. sea bass (Houdelet et al, 2023), similarly of what observed in this study by heat stress. Overall data shows that in fish, miRNAs play a regulatory role in the thermal plasticity of acclimation and adaptation to drastic temperature changes in the environment.…”

“…In fish, miR-499 plays a role in muscle tissue (Duran et al, 2015;Nachtigall et al, 2015Nachtigall et al, , 2014 and its evolution targeting the intronic region of the myosin heavy chain (MYH14) gene was studied throughout evolution in teleost (Bhuiyan et al, 2013). In a recent publication in E. sea bass, the authors identified higher levels of circulating miR-499 in plasma differentiating males when comparted to differentiating females (Houdelet et al, 2023). Another example of a male-like miRNAs in fish gonads is the miR-135, which is a biomedical marker in humans due to its involvement in many cancer and disorders like Alzheimer disease (Kadkhoda et al, 2022;Zheng et al, 2021).…”