Eva Blondeau-Bidet

French National Centre for Scientific Research | CNRS · UMR 9190 - MARBEC

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 males...

The red drum Sciaenops ocellatus is a marine fish species of high commercial interest. Despite improvements in current aquaculture practices, there are still concerns about the impact of daily manipulations regarding fish welfare. To investigate how does fish respond to various challenges, S. ocellatus juveniles were submitted to two acute challeng...

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 a model b...

Epigenetic modifications, like DNA methylation, generate phenotypic diversity in fish and ultimately lead to adaptive evolutionary processes. Euryhaline marine species that migrate between salinity-contrasted habitats have received little attention regarding the role of salinity on whole-genome DNA methylation. Investigation of salinity-induced DNA...

Epigenetic modifications, like DNA methylation, generate phenotypic diversity in fish and ultimately lead to adaptive evolutionary processes. Euryhaline marine species that migrate between salinity contrasted habitats have received little attention regarding the role of salinity on whole-genome DNA methylation. Investigation of salinity-induced DNA...

European sea bass (Dicentrarchus labrax) are a major aquaculture species that live in habitats with fluctuating salinities that are sometimes higher than in seawater (SW). Atlantic and West-Mediterranean genetic lineages were compared regarding intestinal neuropeptide receptor expression in SW (36%) and following a two-week transfer to hypersalinit...

In this study, we aimed to investigate the relationship between cortisol and the determination of sexual fate in the commercially important European sea bass (Dicentrarchus labrax). To test our hypothesis, we designed two temperature-based experiments (19 ℃, 21 ℃ and 23 ℃, experiment 1; 16 ℃ and 21 ℃, experiment 2) to assess the effects of these th...

Significance Traditionally, fish sex determination was considered to be governed by genetic or environmental factors. However, many teleost species defy this dichotomy. We combined genomic and transcriptomic approaches to characterize the temperature-dependent polygenic sex determination of European sea bass. We observed that the estimated genetic...

The ontogeny of the digestive capacities in fish is species-specific and its knowledge is essential for understanding the nutritional requirements of fish larvae. While the Amazon basin contains the world's highest fish biodiversity, the molecular basis of the early digestive physiology of the fish species from the Amazon basin have not been report...

Journal of Experimental Marine Biology and Ecology

European sea bass (Dicentrarchus labrax) migrate towards habitats where salinity can reach levels over 60‰, notably in Mediterranean lagoons. D. labrax are genetically subdivided in Atlantic and Mediterranean lineages and have evolved in slightly different salinities. We compared Atlantic and West-Mediterranean populations regarding their capacity...

Temperature and salinity are abiotic factors that affect physiological responses in aquaculture species. The European sea bass (Dicentrarchus labrax) is a temperate species that is generally farmed at 18 °C in seawater (SW). In the wild, its incursions in shallow habitats such as lagoons may result in hyperthermal damage despite its high thermal to...

European sea bass (Dicentrarchus labrax), a major aquaculture species, is distributed along the coasts of the North-Eastern Atlantic Ocean, Mediterranean and Black Sea. D. labrax enter lagoons and estuaries where salinity fluctuates and sometimes reaches levels over 60‰, notably in Mediterranean lagoons. Keeping in mind that European sea bass are g...

Temperature‐dependent sex determination (TSD) can be observed in multiple reptile and fish species. It is adaptive when varying environmental conditions advantage either males or females. A good knowledge of the thermosensitive period is key to understand how environmental changes may lead to changes in population sex ratio. Here, by manipulating t...

Changes in ocean water temperature associated with global climate change are bound to enormously affect fish populations, with potential major economic consequences in the aquaculture and fisheries industries. A link between temperature fluctuations and changes in fish stress response is well established. In this study, we aimed to assess the effec...

Acclimation to low salinities is a vital physiological challenge for euryhaline fish as the European sea bass Dicentrarchus labrax. This species undertakes seasonal migrations towards lagoons and estuaries where a wide range of salinity variations occur along the year. We have previously reported intraspecific differences in freshwater tolerance, w...

Salinity tolerance is an important trait that governs the ecology of disease‐vector mosquitoes by determining their choice of larval habitat, and consequently their ecological and geographical distribution. Here, we used laboratory strains to determine the osmotic responses of larvae of obligate freshwater disease‐vector mosquitoes (Aedes aegypti,...

The responses of European sea bass to temperature increase and salinity decrease were investigated measuring mRNA expression levels of main genes involved in ion transport. Juvenile fish were pre-acclimated to seawater (SW) at 18 °C (temperate) or 24 °C (warm) for two weeks and then transferred for two weeks to either fresh water (FW) or SW at the...

In teleosts, the regulation of hydromineral balance has a direct impact on several physiological functions, biochemical processes, and can influence behaviour, distribution and survival. As European sea bass Dicentrarchus labrax undertake seasonal migrations from seawater (SW) to brackish, estuarine and fresh water (FW) in their habitat, this study...

Ion uptake mechanisms are diverse in fish species, certainly linked to duplication events that have led to the presence of a multitude of paralogous genes. In fish, Na⁺ uptake involves several ion transporters expressed in different ionocyte subtypes. In the European sea bass Dicentrarchus labrax, several key transporters potentially involved in Na...

Euryhaline milkfish (Chanos chanos) is an important economic species in Taiwan and is able to survive in both seawater (SW) and fresh water (FW). Upon salinity changes, euryhaline fish kidneys play a crucial role in osmoregulation. During this process, Na⁺/K + -ATPase (NKA) mainly functions in providing the driving force for the other ion-transport...

For teleost, the energetic demand for maintenance of the gut is at least five- to eightfold higher than corresponding mass-specific whole animal consumption rates. This is due to the multifunctionality of the gut involved in energy consuming roles such as digestive, immune and osmoregulatory processes leading to energetic trade-offs. The nutritiona...

Ion uptake mechanisms are diverse in fish species, certainly linked to duplication events that have led to the presence of a multitude of paralogous genes. Na+ uptake is tightly linked to proton and nitrogen excretion and involves several ion transporters. In the European sea bass, several key transporters potentially involved in Na+ uptake have be...

Stress enhances or inhibits neurogenesis in mammals and some fish species. The link between the two processes is still unclear. Most studies have been performed in very specific stressful or altered environments. Despite the known inter-individual divergence in coping abilities within populations, the relationship between the stress axis and neurog...

Three-spined sticklebacks (Gasterosteus aculeatus L.) of the Camargue region (Rhone delta, northern Mediterranean Sea) occupy coastal mesohaline lagoons and freshwater canals. In this study, the acclimation capacity to different salinities of a population living in freshwater canals was investigated. Freshwater (FW; 5 ‰) individuals were compared t...

The European sea bass Dicentrarchus labrax is a euryhaline species that lives in the sea and undertakes seasonal migrations in lagoons or estuaries. These habitats are characterized by high salinity fluctuations and often low salinities. Sea bass have thus to efficiently osmoregulate and to be able to switch between hypo-and hyperosmoregulation. Se...

The Na+/K+-ATPase (NKA) is considered as the main pump involved in active ion transport. In the European sea bass, Dicentrarchus labrax, we found two genes encoding for the alpha 1 subunit isoforms (NKA α1a and NKA α1b). NKA α1a and NKA α1b isoform amino acid (aa) sequences were compared through phylogeny and regarding key functional motifs between...

In this era of increasing environmental changes, studying how species cope with this stress arises as a key research issue. Macrostomum lignano, as other intertidal organisms, are adapted to face variations in their environmental conditions, and are thus interesting models for these studies. We here analyse their physiological strategy to face sali...

Intertidal organisms must face daily cycles of environmental variations but also unpredictable events, which occurrence should increase due to global changes. As an interstitial organism dealing with such challenges, Macrostomum lignano is a suitable model species for studies focusing on physiological adaptations to environmental constraints. In th...

Fasting and refeeding occur naturally in predators but this is largely ignored when dealing with farmed fish. Therefore, the effects of 3-week fasting and re-alimentation (2.5% of the individual body mass) were investigated using two genetically selected populations (F2 generation) of 250 g juvenile sea bass (Dicentrarchus labrax L.). Blood osmolar...

In the context of global change, there is an urgent need for researchers in conservation physiology to understand the physiological mechanisms leading to the acquisition of stress acclimation phenotypes. Intertidal organisms continuously cope with drastic changes in their environmental conditions, making them outstanding models for the study of phy...

The Na+/K+-ATPase (NKA), considered as the main pump involved in active ion transport, presents in the European sea-bass (Dicentrarchus labrax) two isoforms of the alpha 1 subunit (NKA α1a and α1b). Analysis of amino acid (aa) sequences of both isoforms revealed a high degree of conservation across teleosts. NKA α1a and α1b isoform aa sequences are...

Colonizations from marine to freshwater (FW) environments constitute dramatic evolutionary transitions in the history of life, and pose great osmoregulatory challenges for organisms. The copepod Eurytemora affinis, which lacks gills, has recently invaded FW habitats multiple times independently in North America. We measured hemolymph osmolality for...

European sea-bass Dicentrarchus labrax and milkfish Chanos chanos are eurytherm and euryhaline species that have to cope with fluctuating physico-chemical parameters in their habitats. The temperate species (D. labrax) is generally farmed at temperatures close to 18°C and seawater (SW, 34ppt). In the wild, D. labrax migrates in spring to lagoons fo...

The copepod Eurytemora affinis has an unusually broad salinity range, as some populations have recently invaded freshwater habitats independently from their ancestral saline habitats. Prior studies have shown evolutionary shifts in ion transporter activity during freshwater invasions and localization of ion transporters in newly discovered "Crusali...

4-Nonylphenol (4-NP) is a synthetic organic chemical able to mimick the action of the nat- ural female hormone 17 β -estradiol (E2) by binding to the E2 receptor [...]

Dicentrarchus labrax migrates between sea (SW), brackish and fresh water (FW) where chloride concentrations and requirements for chloride handling change: in FW, fish absorb chloride and restrict renal losses; in SW, they excrete chloride. In this study, the expression and localization of ClC-3 and Na(+)/K(+)-ATPase (NKA) were studied in fish adapt...

The European eel (Anguilla anguilla), a catadromous species, breeds in the sea and migrates to estuarine, lagoon or freshwater habitats for growth and development. Yellow eels, exposed to low or fluctuating salinities, are also exposed to multiple other stressors as pollution, over-fishing and parasitism, which contribute to the dramatic decrease o...

The gilthead sea bream, Sparus aurata, is a euryhaline teleost that hatches in the open sea. The larvae drift to the coast and juveniles migrate into estuaries and lagoons where the salinity of the water may vary from brackish to hyper-saline. The ontogeny of osmoregulation in Sparus aurata was studied at successive stages, from day 1 (D1) post-hat...