Project description:A comparative genomic project aiming to sequence the genomes of isolates representing the diversity of the Legionella pneumophila population
Project description:The effect of krill powder, a mixed source of protein and n-3 PUFAs from Antarctic Krill (Euphausia superba), on hepatic gene expression was analyzed in CBA/J mice. Mice were fed a low-fat control diet or a 3% (w/w) krill powder low-fat diet for three months. Gene expression profiling on liver samples revealed that the krill powder supplemented diet modulated a large number of pathways compared to the control diet, and we focused on the genes involved in metabolic processes. Pathways involved β-oxidation, glucose metabolism, and amino acid catabolism were downregulated. In contrast, genes involved in the mitochondrial electron transport chain were upregulated. Thus, a krill powder supplemented diet had potent and specific effects on energy metabolism and oxidative phosphorylation at the gene level. This indicates that krill powder supplementation could be an approach to prevent age-related decline in mitochondrial respiratory chain function and weight loss.
Project description:Dietary supplementation with ω-3 polyunsaturated fatty acids (ω-3 PUFAs), specifically the fatty acids docosahexaenoic acid (DHA; 22:6 ω-3) and eicosapentaenoic acid (EPA; 20:5 ω-3), is known to have beneficial health effects including improvements in glucose and lipid homeostasis and modulation of inflammation. To evaluate the efficacy of two different sources of ω-3 PUFAs, we performed gene expression profiling in the liver of mice fed diets supplemented with either fish oil or krill oil. We found that ω-3 PUFA supplements derived from a phospholipid krill fraction (krill oil) downregulated the activity of pathways involved in hepatic glucose production as well as lipid and cholesterol synthesis. The data also suggested that krill oil-supplementation increases the activity of the mitochondrial respiratory chain. Surprisingly, an equimolar dose of EPA and DHA derived from fish oil modulated fewer pathways than a krill oil-supplemented diet and did not modulate key metabolic pathways regulated by krill oil, including glucose metabolism, lipid metabolism and the mitochondrial respiratory chain. Moreover, fish oil upregulated the cholesterol synthesis pathway, which was the opposite effect of krill supplementation. Neither diet elicited changes in plasma levels of lipids, glucose or insulin, probably because the mice used in this study were young and were fed a low fat diet. Further studies of krill oil supplementation using animal models of metabolic disorders and/or diets with a higher level of fat may be required to observe these effects.
Project description:Krill oil is a dietary supplement derived from Antarctic krill; a small crustacean found in the ocean. Krill oil is a rich source of omega-3 fatty acids, specifically eicosapentaenoic acid and docosahexaenoic acid, as well as the antioxidant astaxanthin. The aim of this study was to investigate the effects of krill oil supplementation, compared to placebo oil (high oleic sunflower oil added astaxanthin), in vivo on energy metabolism and substrate turnover in skeletal muscle cells. Skeletal muscle cells (myotubes) were obtained before and after a 7-week krill oil or placebo oil intervention, and glucose and oleic acid metabolism and leucine accumulation, as well as effects of different stimuli in vitro, were studied in the myotubes. In vivo intervention with krill oil increased oleic acid oxidation and leucine accumulation in skeletal muscle cells, however no effects were observed on glucose metabolism. The krill oil-intervention-induced increase in oleic acid oxidation correlated negatively with changes in serum low-density lipoprotein (LDL) concentration. In addition, myotubes were also exposed to krill oil in vitro. The in vitro study revealed that 24 h of krill oil treatment increased both glucose and oleic acid metabolism, enhancing energy substrate utilization. Transcriptomic analysis comparing myotubes obtained before and after krill oil-supplementation identified differentially expressed genes associated with e.g. glycolysis/gluconeogenesis, metabolic pathways and calcium signaling pathway, while proteomic analysis demonstrated upregulation of e.g. LDL-receptor in myotubes obtained after krill oil intervention. These findings suggest that krill oil intervention promotes increased fuel metabolism and protein synthesis in human skeletal muscle cells, with potential implications for metabolic health.
Project description:Antarctic krill (Euphausia superba) is a high latitude pelagic organism which plays a central role in the Southern Ocean ecosystem. E. superba shows daily and seasonal rhythms in physiology and behaviour, which are synchronized with the environmental cycles of its habitat. Recently, the main components of the krill circadian machinery have been identified and characterized. However, the exact mechanisms through which the endogenous timing system operates the control and regulation of the overt rhythms remains only partially understood. Here we investigate the involvement of the circadian clock in the temporal orchestration of gene expression by using a newly developed version of a krill microarray platform. The analysis of transcriptome data from krill exposed to both light-dark cycles (LD 18:6) and constant darkness (DD), has led to the identification of 1,564 putative clock-controlled genes. A remarkably large proportion of such genes, including several clock components (clock, period, cry2, vrille, and slimb), show oscillatory expression patterns in DD, with a periodicity shorter than 24 hours. Energy-storage pathways appear to be regulated by the endogenous clock in accordance with their ecological relevance in daily energy managing and overwintering. Our results provide the first representation of the krill circadian transcriptome under laboratory, free-running conditions. This SuperSeries is composed of the SubSeries listed below.
Project description:Dietary supplementation with ω-3 polyunsaturated fatty acids (ω-3 PUFAs), specifically the fatty acids docosahexaenoic acid (DHA; 22:6 ω-3) and eicosapentaenoic acid (EPA; 20:5 ω-3), is known to have beneficial health effects including improvements in glucose and lipid homeostasis and modulation of inflammation. To evaluate the efficacy of two different sources of ω-3 PUFAs, we performed gene expression profiling in the liver of mice fed diets supplemented with either fish oil or krill oil. We found that ω-3 PUFA supplements derived from a phospholipid krill fraction (krill oil) downregulated the activity of pathways involved in hepatic glucose production as well as lipid and cholesterol synthesis. The data also suggested that krill oil-supplementation increases the activity of the mitochondrial respiratory chain. Surprisingly, an equimolar dose of EPA and DHA derived from fish oil modulated fewer pathways than a krill oil-supplemented diet and did not modulate key metabolic pathways regulated by krill oil, including glucose metabolism, lipid metabolism and the mitochondrial respiratory chain. Moreover, fish oil upregulated the cholesterol synthesis pathway, which was the opposite effect of krill supplementation. Neither diet elicited changes in plasma levels of lipids, glucose or insulin, probably because the mice used in this study were young and were fed a low fat diet. Further studies of krill oil supplementation using animal models of metabolic disorders and/or diets with a higher level of fat may be required to observe these effects. Twenty-one microarrays: three diets (CO, FO, KO) x seven mice per diet x one microarray per mouse
Project description:Purpose: Supplementation with krill oil has shown effects on whole-body lipid and glucose metabolism, as well as on skeletal muscle strength and function. We previously showed that krill oil intervention in vivo promoted fatty acid metabolism and protein synthesis in cultured human myotubes in a two-dimensional (2D) model. The aim of this study was to explore the effects of krill oil supplementation in vivo in a 3D myosphere model and to compare the 3D and 2D models. Methods: Myospheres were formed from myoblasts obtained before and after 7 weeks of in vivo krill oil intervention. Glucose and oleic acid metabolism were assessed, and transcriptomic and proteomic analyses were performed. Results: In vivo intervention with krill oil increased glucose metabolism in myospheres, while no effect was observed on fatty acid metabolism. Transcriptomic analyses of myospheres after krill oil intervention showed increased expression of genes involved in pathways like motor proteins and hypertrophy, as well as in calcium signaling, of which motor proteins and hypertrophy pathways have not been described in 2D myotube cultures. Proteomic analyses after krill oil intervention showed increased expression of proteins in glycolysis/gluconeogenesis and fatty acid degradation. Comparison of proteins expressed in the 3D myosphere model and a 2D myotube model at the basal level showed that in myospheres, mitochondrial gene expression and translation dominated, while in 2D cultures, mitochondrial organization and response to oxidative stress were more important. Conclusion: These findings suggest that in vivo krill oil intervention induces different metabolic effects when comparing 3D and 2D cultures. In contrast to the 2D model, data obtained with the 3D model showed gene expression changes that are more compatible with previously observed results in vivo concerning skeletal muscle motoric function. Hence, the 3D model might better reflect krill oil-induced modifications in skeletal muscle performance in vivo than the 2D model.