Dataset Information

Liver transcriptome analysis in gilthead sea bream upon exposure to low temperature.

ABSTRACT: BACKGROUND: Water temperature greatly influences the physiology and behaviour of teleost fish as other aquatic organisms. While fish are able to cope with seasonal temperature variations, thermal excursions outside their normal thermal range might exceed their ability to respond leading to severe diseases and death.Profound differences exist in thermal tolerance across fish species living in the same geographical areas, promoting for investigating the molecular mechanisms involved in susceptibility and resistance to low and high temperatures toward a better understanding of adaptation to environmental challenges. The gilthead sea bream, Sparus aurata, is particularly sensitive to cold and the prolonged exposure to low temperatures may lead to the "winter disease", a metabolic disorder that significantly affects the aquaculture productions along the Northern Mediterranean coasts during winter-spring season. While sea bream susceptibility to low temperatures has been extensively investigated, the cascade of molecular events under such stressful condition is not fully elucidated. RESULTS: In the present study two groups of wild sea bream were exposed for 21 days to two temperature regimes: 16?±?0.3°C (control group) and 6.8?±?0.3°C (cold-exposed group) and DNA microarray analysis of liver transcriptome was carried out at different time points during cold exposure.A large set of genes was found to be differentially expressed upon cold-exposure with increasingly relevant effects being observed after three weeks at low temperature. All major known responses to cold (i.e. anti-oxidant response, increased mitochondrial function, membrane compositional changes) were found to be conserved in the gilthead sea bream, while, evidence for a key role of unfolded protein response (UPR) to endoplasmic reticulum (ER) stress, during short- and long-term exposure to cold is reported here for the first time. CONCLUSIONS: Transcriptome data suggest a scenario where oxidative stress, altered lipid metabolism, ATP depletion and protein denaturation converge to induce ER stress. The resulting UPR activation further promotes conditions for cell damage, and the inability to resolve ER stress leads to severe liver dysfunction and potentially to death.

SUBMITTER: Mininni AN

PROVIDER: S-EPMC4167152 | biostudies-literature | 2014

REPOSITORIES: biostudies-literature

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Liver transcriptome analysis in gilthead sea bream upon exposure to low temperature.

Mininni Alba N AN Milan Massimo M Ferraresso Serena S Petochi Tommaso T Di Marco Patrizia P Marino Giovanna G Livi Silvia S Romualdi Chiara C Bargelloni Luca L Patarnello Tomaso T

BMC genomics 20140906

<h4>Background</h4>Water temperature greatly influences the physiology and behaviour of teleost fish as other aquatic organisms. While fish are able to cope with seasonal temperature variations, thermal excursions outside their normal thermal range might exceed their ability to respond leading to severe diseases and death.Profound differences exist in thermal tolerance across fish species living in the same geographical areas, promoting for investigating the molecular mechanisms involved in susc ...[more]

PMID: 25194679

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Project description:In Sparus aurata, seasonal temperature variations outside the normal thermal range, may trigger physiological responses leading to pathologies and death. In the present study two groups of wild sea bream were exposed for 21 days to two temperature regimes: 16 Â± 0.3 Â°C (control group) and 6.8 Â± 0.3 Â°C (cold-exposed group). Samples were collected during the acute phase (0, 6 and 24 hours after temperature drop) and upon chronic exposure (21 days). A comparative analysis of gene expression was conducted between S. aurata exposed to 6.8Â°C. Two groups of wild sea breams (120Â±16 g body weight; 21Â±1 cm total length) caught in Valle Bonello were kept in duplicate groups in four 5 m3 circular recycling tanks and acclimated over one month at 16 Â°C (Di Marco et al. 2010). Fish were then exposed for 21 days to two different temperature treatments: 16 Â± 0.3 Â°C (control groups) and 6.8 Â± 0.3 Â°C (cold groups). Both groups were fasted during the trial. Warm and cold water temperature conditions were maintained by supplying tanks with two separate re-circulating systems equipped with mechanical and biological filters. Cold water conditions were achieved by inducing two consecutive temperature drops: water was firstly gradually cooled from 16 Â°C to 12 Â°C at a rate of 1Â°C day -1 and then reduced from 12 Â°C to 6.8 Â°C within 24 h. This temperature was then kept for 21 days. Ten fish per treatment were sampled at different intervals during acute: 0 (T1), 6 (T2) and 24 hours (T3), and chronic exposure (21 days; T4) to low temperature. Fish were firstly anaesthetized in a solution of tricaine methanesulphonate (300 mg/l; MS 222, Finquel) in a 30-litre bucket and then euthanized by severing their spinal cord. Liver samples (about 30 mg) were collected from each specimen, incubated in RNA later at 4 Â°C for 24 h and then stored at -20 Â°C. Total RNA was extracted from tissue samples using the RNAeasy Mini Kit (Qiagen, Hilden, Germany). RNA concentration was determined using a UV-Vis spectrophotometer NanoDropÂ® ND-1000 (NanoDrop Technologies, Wilmington, USA). RNA integrity and quality was evaluated by means of Agilent 2100 Bioanalyzer (Agilent Technologies, Palo Alto, CA) and Expert software according to Ferraresso et al. (2008). RNA integrity number (RIN) index was calculated for each sample that provides a numerical assessment of RNA integrity. This value facilitates the standardization of the quality interpretation; only RNAs with RIN >8 were used for further microarray experiments. Once single RNA samples were extracted and measured, 3 pools (Pool_A consisting of four individuals, Pool_B and _C of three) per each sampling-time point were prepared. This was aimed at getting a sufficient statistical power which is reached by a minimum of three biological replicates per analysed point and at reducing microarray analysis cost. To perform DNA microarray analyses has been used the microarray platform GPL6467 (Ferraresso et al. 2008). Sample labelling and hybridization were performed according to the Agilent One-Color Microarray-Based Gene Expression Analysis protocol. For each of 24 liver pools 500 ng of total RNA were linearly amplified and labelled with Cy3-dCTP, using the Low RNA Input Linear Amplification Kit PLUS one-color (Agilent Technologies). A total of 24 Agilent 4 x 44K sea bream microarrays (12 samples from both control and cold groups) were then hybridized. An Agilent G2565BA DNA microarray scanner was used to scan arrays at 5 Âµm resolution, Feature Extraction Software 9.5.1 was then used to process and analyse array images. The software returns a series of spot quality measures in order to evaluate the goodness and the reliability of spot intensity estimates. Filtering and cyclic lowess normalization were performed using R statistical software (http://www.r-project.org/).

Project description:World population is expected to increase to approximately 9 thousand million people by 2050 with a consequent food security decline. Besides, climate change is a major challenge that humanity is facing, with a predicted rise in mean sea surface temperature of more than 2°C during this century. This study aims to determine whether a rearing temperature of 19, 24, or 28°C may influence musculoskeletal development and muscle lipid metabolism in gilthead sea bream juveniles. The expression of growth hormone (GH)/insulin-like growth factors (IGFs) system-, osteogenic-, myogenic-, and lipid metabolism-related genes in bone and/or white muscle of treated fish, and the in vitro viability, mineralization, and osteogenic genes expression in primary cultured cells derived from bone of the same fish were analyzed. The highest temperature significantly down-regulated igf-1, igf-2, the receptor igf-1ra, and the binding proteins igfbp-4 and igfbp-5b in bone, and in muscle, igf-1 and igf-1ra, suggesting impaired musculoskeletal development. Concerning myogenic factors expression, contrary responses were observed, since the increase to 24°C significantly down-regulated myod1 and mrf4, while at 28°C myod2 and myogenin were significantly up-regulated. Moreover, in the muscle tissue, the expression of the fatty acid transporters cd36 and fabp11, and the lipases lipa and lpl-lk resulted significantly increased at elevated temperatures, whereas ?-oxidation markers cpt1a and cpt1b were significantly reduced. Regarding the primary cultured bone-derived cells, a significant up-regulation of the extracellular matrix proteins on, op, and ocn expression was found with increased temperatures, together with a gradual decrease in mineralization along with fish rearing temperature. Overall, these results suggest that increasing water temperature in this species appears to induce unfavorable growth and development of bone and muscle, through modulating the expression of different members of the GH/IGFs axis, myogenic and osteogenic genes, while accelerating the utilization of lipids as an energy source, although less efficiently than at optimal temperatures.

Dataset Information

Liver transcriptome analysis in gilthead sea bream upon exposure to low temperature.

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Liver transcriptome analysis in gilthead sea bream upon exposure to low temperature.

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