Biology subjects

Skiba-Cassy, S.

Publications and source records attributed to Skiba-Cassy, S..

5 recordsLinked to original sources

bioRxiv2023

Gut physiology of rainbow trout (Oncorhynchus mykiss) is influenced more by 1 short-term fasting followed by refeeding than by feeding fishmeal-free diets

Supplementing a fishmeal-free diet with yeast extract improves rainbow trout (Oncorhynchus mykiss) growth performance and modulates the hepatic and intestinal transcriptomic response. These effects are often observed in the long term, but are not well documented after short periods of fasting. Fasting for a few days is a common practice in fish farming, especially before handling the fish, such as for short sorting, tank transfers and vaccinations. In the present study, rainbow trout were subjected to a four-day fast and then refed, for eight days, a conventional diet containing fishmeal (control diet) or alternative diets composed of terrestrial animal by-products supplemented or not with a yeast extract. During the refeeding period alone, most of the parameters considered did not differ significantly in response to the different feeds. Only the expression of claudin-15 was upregulated in fish fed the yeast-supplemented diet compared to the control diet. Conversely, fasting followed by refeeding significantly influenced most of the parameters analyzed. In the proximal intestine, the surface area of villi significantly increased and the density of goblet cell tended to decrease during refeeding. Although no distinct plasma immune response or major signs of gut inflammation were observed, some genes involved in the structure, complement pathway, antiviral functions, coagulation and endoplasmic reticulum stress response of the liver and intestine were significantly regulated by refeeding after fasting. These results indicate that short-term fasting, as commonly practiced in fish farming, significantly alters the physiology of the liver and intestine regardless of the composition of the diet.

physiology↗

bioRxiv2023

Yeast extract improves growth in rainbow trout (Oncorhynchus mykiss) fed a fishmeal-free diet and modulates the hepatic and distal intestine transcriptomic profile

Replacing fishmeal with alternative protein sources and improving new ingredients diets with feed additives are major objectives in aquaculture. The aim of this study was to evaluate benefits for rainbow trout (Oncorhynchus mykiss) of supplementing a fishmeal-free diet, composed of processed animal proteins, with yeast extract. Juvenile rainbow trout (initial weight 37 {+/-} 2 g) were fed either with a control diet (19% fishmeal) or with a diet based on terrestrial animal by-products (17%) supplemented or not with 3% of yeast extract. Effects of the diets were evaluated in a 4-week digestibility trial and a 12-week growth experiment. Fish health was investigated by measuring plasma immune markers and performing histological study of the gut. Underlying molecular responses were investigated using unbiased transcriptomic analysis of the liver and distal intestine. Results indicated that supplementing with 3% yeast extract did not influence nutrient digestibility substantially. Nevertheless, fish fed the supplemented fishmeal-free diet grew more than those fed the non-supplemented processed animal protein diet. Plasma and structural parameters indicated no exacerbated immune response or signs of intestinal inflammation in fish fed the fishmeal-free diets. However, plasma total immunoglobulin M levels and intestinal villi were significantly higher in fish fed the diet supplemented with yeast extract. The transcriptomic analysis revealed that the diets influenced immune, inflammatory, pathogen fighting and coagulation gene-related expressions. These results suggest that the dietary inclusion of yeast can enhance a fishmeal-free diet by improving rainbow trout performances and potentially their robustness.

physiology↗

bioRxiv2021

Effect of a low water salinity on oocyte maturation, oocyte hydration, ovulation and egg quality in rainbow trout.

Water salinity is an important environmental factor known to have detrimental effects on salmonid reproduction, mostly when migrating female broodfish are held in sea water. In contrast, data obtained in freshwater are scarce and the impact of low water salinity, and more specifically of low water concentrations in sodium, chloride and potassium, during reproduction in freshwater is currently unknown. For this reason, and because ion and water fluxes are critical for the final steps of the female gamete formation, including oocyte hydration and ovulation, the aim of the present study was to investigate the impact of low salinity water on final oocyte maturation, ovulation and, ultimately, on egg quality, using rainbow trout as a physiological model and relevant aquaculture species. Fish from the same commercial strain were raised either in a site characterized by low concentrations of Na+, K+, and Cl- ions in the water or in a closely located control site exhibiting higher concentration in these elements. Egg quality and duration of final oocyte maturation were investigated using innovative phenotyping tools such as automatic assessment of egg viability using the VisEgg system and non-invasive echograph-based monitoring of final oocyte maturation duration, respectively. Oocyte hydration during final oocyte maturation and after ovulation was also investigated. Finally, molecular phenotyping was performed using real-time PCR-based monitoring of several key players of final oocyte maturation and ovulation associated with ion and water transport, inflammation, proteolytic activity, and coagulation. Oocyte hydration and gene expression data were analyzed in the light of the duration of final oocyte maturation. Here we show that low water salinity (i.e., low water concentration in chloride, sodium and potassium) negatively influences final oocyte maturation, ovulation and, ultimately, egg quality. Low water salinity triggered delayed ovulation and lower oocyte viability. When investigating the impact of low water salinity on final oocyte maturation duration, individuals presenting the most severe phenotypes exhibited impaired oocyte hydration and abnormally reduced gene expression levels of several key players of the ovulatory process. While the under expression of water (i.e., aquaporins) and ion (i.e., solute carriers) transporters is consistent with impaired oocyte hydration, our observations also indicate that the overall ovulatory gene expression program is disrupted. Our results raise the question of the mechanisms underlying the negative influence of low salinity water on the dynamics of the preovulatory phase, on the control of the oocyte homeostasis, including hydration, and on the overall success of the maturation-ovulation process. HighlightsO_LILow water salinity impairs final oocyte maturation and egg quality in rainbow trout C_LIO_LILow water salinity induces delayed ovulation and impaired oocyte hydration C_LIO_LILow water salinity induces a dysregulation of several key ovulatory genes C_LIO_LIMonitoring of final oocyte maturation can be performed using ultrasound staging C_LI

physiology↗

bioRxiv2021

Circulating miRNA diversity, origin and response to changing metabolic and reproductive states, new insights from the rainbow trout

Circulating miRNAs (c-miRNAs) are found in most, if not all, biological fluids and are becoming well established biomarkers of many human pathologies. The aim of the present study was to investigate the potential of c-miRNAs as biomarkers of reproductive and metabolic states in fish, a question that has received little attention. Plasma was collected throughout the reproductive cycle from rainbow trout females subjected to two different feeding levels to trigger contrasting metabolic states; ovarian fluid was sample at ovulation. Fluid samples were subjected to small RNA-seq analysis followed by quantitative PCR validation for a subset of promising c-miRNA biomarkers. A comprehensive miRNA repertoire, which was lacking in trout, was first established to allow subsequent analysis. We first showed that biological fluids miRNAomes are complex and encompass a high proportion of the overall species miRNAome. While sharing a high proportion of common miRNAs, plasma and ovarian fluid miRNAomes exhibited strong fluid-specific signatures. We further showed that the plasma miRNAome exhibited major significant changes depending on metabolic and reproductive state. We subsequently identified three (miR-1-1/2-3p, miR-133-a-1/2-3p and miR-206-3p) evolutionarily conserved muscle-specific miRNA that accumulate in the plasma in response to high feeding rates, making these myomiRs strong candidate biomarkers of active myogenesis. We also identified miR-202-5p as a candidate biomarker for reproductive success that could be used to predict ovulation and/or egg quality. These highly promising results reveal the high potential of c-miRNAs as physiologically relevant biomarkers and pave the way for the use of c-miRNAs for non-invasive phenotyping in various fish species.

genomics↗

bioRxiv2019

Kinetic study of the expression of genes related to hepatic steatosis, global intermediate metabolism and cellular stress during overfeeding in mule ducks

Induced by overfeeding, hepatic steatosis is a reversible process exploited for \"foie gras\" production. To better understand the mechanisms underlying this non-pathological phenomenon, we analysed the physiological responses of the mule duck to cope with 22 carbohydrate meals. A kinetic analysis of intermediate metabolism and cell protection mechanisms was performed during overfeeding. As expected, dietary carbohydrates are up taken mainly by the liver (chrebp, glut1/2/8) and converted into lipids (acox, scd1, acsl1, fas, dgat2). Our study showed an activation of cholesterol biosynthetic pathway with significant correlations between plasma cholesterol, expression of key genes (hmgcr, soat1) and liver weight. Results revealed an activation of insulin and amino acid cell signalling pathway suggesting that ducks boost insulin sensitivity to raise glucose uptake and use via glycolysis and lipogenesis. Expression of cpt1a, acad, hadh suggested an induction of beta-oxidation probably to remove part of newly synthesized lipids and avoid lipotoxicity. Cellular stress analysis revealed an upregulation of autophagy-related gene expression (atg8, atg9, sqstm1) in contrast with an induction of cyp2e1 suggesting that autophagy could be suppressed. Lamp2a and plin2 enhanced, conflicting with the idea of an inhibition of lipophagy. Hsbp1 overexpression indicated that mechanisms are carried out during overfeeding to limit cellular stress and apoptosis to prevent the switch to pathological state. Atf4 and asns overexpression reflects the nutritional imbalance during overfeeding. These results permitted to highlight the mechanisms enabling mule ducks to efficiently handle the huge starch overload and reveal potential biomarker candidates of hepatic steatosis as plasma cholesterol for liver weight.

physiology↗