The aim of the current study was to phenotype fish metabolism and the transcriptionally-mediated ... more The aim of the current study was to phenotype fish metabolism and the transcriptionally-mediated response of hepatic mitochondria of gilthead sea bream to intermittent and repetitive environmental stressors: i) changes in water temperature (T-ST), ii) changes in water level and chasing (C-ST) and iii) multiple sensory perception stressors (M-ST). Gene expression profiling was done using a quantitative PCR array of 60 mitochondria-related genes, selected as markers of transcriptional regulation, oxidative metabolism, respiration uncoupling, antioxidant defense, protein import/folding/assembly, and mitochondrial dynamics and apoptosis. The mitochondrial phenotype mirrored changes in fish performance, haematology and lactate production. T-ST especially up-regulated transcriptional factors (PGC1α, NRF1, NRF2), rate limiting enzymes of fatty acid β-oxidation (CPT1A) and tricarboxylic acid cycle (CS), membrane translocases (Tim/TOM complex) and molecular chaperones (mtHsp10, mtHsp60, mtHsp70) to improve the oxidative capacity in a milieu of a reduced feed intake and impaired haematology. The lack of mitochondrial response, increased production of lactate and negligible effects on growth performance in C-ST fish were mostly considered as a switch from aerobic to anaerobic metabolism. A strong downregulation of PGC1α, NRF1, NRF2, CPT1A, CS and markers of mitochondrial dynamics and apoptosis (BAX, BCLX, MFN2, MIRO2) occurred in M-ST fish in association with the greatest circulating cortisol concentration and a reduced lactate production and feed efficiency, which represents a metabolic condition with the highest allostatic load score. These findings evidence a high mitochondrial plasticity against stress stimuli, providing new insights to define the threshold level of stress condition in fish.
This study is the first step investigating a new food chain, using Zophobas morio as a potential ... more This study is the first step investigating a new food chain, using Zophobas morio as a potential " vehicle " to transport amino acids (AA) from Norwegian kelp (Ascophyllum nodosum) into the insect body. Additionally, suitability of Z. morio as a dietary protein substitute for fishmeal (FM) in aquaculture feeds, was evaluated. Proximate composition (dry matter, ash, protein, fat and energy) and complete (free + hydrolysed + tryptophan) AA profiles were determined for Z. morio fed with kelp granulate or oat meal. Using principle component analysis we identified similarities and differences in essential AA between diets and Z. morio fed with these diets. AA scores were calculated to evaluate protein quality of Z. morio. Results showed a slight enrichment in several essential AA for Z. morio fed kelp granulate. Protein level of Z. morio in this study fell within the ranges of protein requirements for fish. All essential AA for fish were present in Z. morio. Based on AA scores it was concluded that methionine would be first limiting. Overall, protein levels and AA profiles showed that Z. morio fed with kelp granulate can be seen as an interesting candidate to replace FM in aquatic diets.
The aim of the current study was to phenotype fish metabolism and the transcriptionally-mediated ... more The aim of the current study was to phenotype fish metabolism and the transcriptionally-mediated response of hepatic mitochondria of gilthead sea bream to intermittent and repetitive environmental stressors: i) changes in water temperature (T-ST), ii) changes in water level and chasing (C-ST) and iii) multiple sensory perception stressors (M-ST). Gene expression profiling was done using a quantitative PCR array of 60 mitochondria-related genes, selected as markers of transcriptional regulation, oxidative metabolism, respiration uncoupling, antioxidant defense, protein import/folding/assembly, and mitochondrial dynamics and apoptosis. The mitochondrial phenotype mirrored changes in fish performance, haematology and lactate production. T-ST especially up-regulated transcriptional factors (PGC1α, NRF1, NRF2), rate limiting enzymes of fatty acid β-oxidation (CPT1A) and tricarboxylic acid cycle (CS), membrane translocases (Tim/TOM complex) and molecular chaperones (mtHsp10, mtHsp60, mtHsp70) to improve the oxidative capacity in a milieu of a reduced feed intake and impaired haematology. The lack of mitochondrial response, increased production of lactate and negligible effects on growth performance in C-ST fish were mostly considered as a switch from aerobic to anaerobic metabolism. A strong downregulation of PGC1α, NRF1, NRF2, CPT1A, CS and markers of mitochondrial dynamics and apoptosis (BAX, BCLX, MFN2, MIRO2) occurred in M-ST fish in association with the greatest circulating cortisol concentration and a reduced lactate production and feed efficiency, which represents a metabolic condition with the highest allostatic load score. These findings evidence a high mitochondrial plasticity against stress stimuli, providing new insights to define the threshold level of stress condition in fish.
This study is the first step investigating a new food chain, using Zophobas morio as a potential ... more This study is the first step investigating a new food chain, using Zophobas morio as a potential " vehicle " to transport amino acids (AA) from Norwegian kelp (Ascophyllum nodosum) into the insect body. Additionally, suitability of Z. morio as a dietary protein substitute for fishmeal (FM) in aquaculture feeds, was evaluated. Proximate composition (dry matter, ash, protein, fat and energy) and complete (free + hydrolysed + tryptophan) AA profiles were determined for Z. morio fed with kelp granulate or oat meal. Using principle component analysis we identified similarities and differences in essential AA between diets and Z. morio fed with these diets. AA scores were calculated to evaluate protein quality of Z. morio. Results showed a slight enrichment in several essential AA for Z. morio fed kelp granulate. Protein level of Z. morio in this study fell within the ranges of protein requirements for fish. All essential AA for fish were present in Z. morio. Based on AA scores it was concluded that methionine would be first limiting. Overall, protein levels and AA profiles showed that Z. morio fed with kelp granulate can be seen as an interesting candidate to replace FM in aquatic diets.
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