Effects of high stocking density and mild hypoxia on gilthead sea bream intestinal transcriptome and microbiome
| Autor: | Toxqui-Rodríguez, S., Naya-Català, Fernando, Holhorea, Paul George, Calduch-Giner, Josep A., Piazzon de Haro, María Carla, Sitjà-Bobadilla, Ariadna, Pérez-Sánchez, Jaume |
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| Přispěvatelé: | European Commission |
| Jazyk: | angličtina |
| Rok vydání: | 2022 |
| Popis: | Trabajo presentado en Aquaculture Europe, celebrado en Rimini (Italia) del 27 al 30 de septiembre de 2022. [Introduction]: Studies in gilthead sea bream evidenced that high stocking densities exacerbate the negative impact of reduced oxygen availability, showing transcriptional analyses a different contribution of analyzed tissues (liver ≥ heart > muscle > blood) to the hypoxic- and crowding stress-mediated responses to cope with a changing environment (Martos-Sitcha et al., 2019). Moreover, blood metabolic and muscle transcriptomic landmarks indicate that mild hypoxia induces a hypometabolic state, increasing the contribution of lipid metabolism to the whole energy supply to preserve the aerobic energy production during exercise (Naya-Català et al., 2021a). The intestinal microbiota also has key effects on host health and welfare, and these complex populations tightly interact with the host affecting local and systemic physiological functions (Naya-Català et al., 2021b). Thus, the aim of the current study was to assess how mild hypoxia and high stocking rearing conditions affect the intestinal health of gilthead sea bream by applying a hologenomic approach to determine the host-microbiota interactions. [Methods]. Two-year-old gilthead sea bream (450-500 g) were tagged and distributed in 3,000 L tanks to achieve three different initial rearing densities (low, LD: 6 kg/m3; medium, MD: 12 kg/m3; high, HD: 22 kg/m3). Fish were fed close to satiety with a commercial diet from May to June (8 weeks) under natural photoperiod and temperature conditions at our latitude (40°5’N;0°10’E), varying the concentration of dissolved oxygen from 6-5 ppm in LD fish to 5-4 ppm in MD fish, and 4-3 ppm in HD fish. At the end of the trial, the growth rate of HD fish was 40% lower than that of MD/LD fish, and randomly selected fish from each group were taken to obtain tissue and mucus samples from the anterior intestine. RNA extracted from the anterior intestine from 10 fish/group was sequenced using NovaSeq PE150 (50 M reads/sample), and reads were assembled and mapped against the gilthead sea bream genome. DESeq2 was used to extract genes with P < 0.05 in all comparisons, that were used to perform discriminant and cluster analysis to determine the number of differentially expressed genes among conditions. K-means, GO and KEGG enrichment analyses were subsequently performed. The V3V4 regions of the 16S rRNA of the mucus DNA samples from the same animals were amplified and sequenced by Illumina MiSeq. After quality filtering, taxonomic assignment was performed with a custom-made pipeline using the RDP database. Alpha diversity was calculated using Phyloseq and beta diversity using PERMANOVA and PLS-DA models. Correlations between differentially expressed genes and discriminant bacteria were studied using the corrplot R package. [Results]: RNAseq and discriminant analyses revealed that a total of 2,813 differentially expressed genes significantly separated the three groups (Fig. 1A). K-means analysis divided these genes into four different clusters according to their expression patterns in each group, separating one cluster of 800 genes with higher expression in LD, a second cluster of 1,103 genes with higher expression in MD, a third cluster of 688 genes with higher expression in HD, and a fourth cluster of 222 genes that gradually increased expression with the stocking density (LD [Conclusions]: Crowding and mild hypoxia had a significant impact on gut health, evidenced by significant changes in host intestinal transcriptome and associated microbial population. These results offer the possibility of developing new tools and approaches for a more precise evaluation of welfare in farmed fish. The ultimate goal is to mitigate the negative impact of stressors related to intensive rearing and climate change on aquaculture production, promoting a more ethical and sustainable production. AQUAEXCEL3.0 (H2020 #871108), EATFISH (H2020 #956697). |
| Databáze: | OpenAIRE |
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