Phenotyping of Drosophila Melanogaster-A Nutritional Perspective

The model organism Drosophila melanogaster was increasingly applied in nutrition research in recent years. A range of methods are available for the phenotyping of D. melanogaster, which are outlined in the first part of this review. The methods include determinations of body weight, body composition, food intake, lifespan, locomotor activity, reproductive capacity and stress tolerance. In the second part, the practical application of the phenotyping of flies is demonstrated via a discussion of obese phenotypes in response to high-sugar diet (HSD) and high-fat diet (HFD) feeding. HSD feeding and HFD feeding are dietary interventions that lead to an increase in fat storage and affect carbohydrate-insulin homeostasis, lifespan, locomotor activity, reproductive capacity and stress tolerance. Furthermore, studies regarding the impacts of HSD and HFD on the transcriptome and metabolome of D. melanogaster are important for relating phenotypic changes to underlying molecular mechanisms. Overall, D. melanogaster was demonstrated to be a valuable model organism with which to examine the pathogeneses and underlying molecular mechanisms of common chronic metabolic diseases in a nutritional context

Screening dietary biochanin A, daidzein, equol and genistein for their potential to increase DHA biosynthesis in rainbow trout (Oncorhynchus mykiss).

Plant oil utilization in aquafeeds is still the most practical option, although it decreases the content of the nutritionally highly valuable omega-3 fatty acids eicosapentaenoic acid (20:5n-3, EPA) and docosahexaenoic acid (22:6n-3, DHA) in fish. Phytoestrogens and their metabolites are putatively able to affect genes encoding proteins centrally involved in the biosynthesis of EPA and DHA due to their estrogenic potential. Thus, the aim of the study was to screen the potential of the phytoestrogens to stimulate the biosynthesis of EPA and DHA in rainbow trout (Oncorhynchus mykiss). Additionally, the potential effects on growth performance, nutrient composition and hepatic lipid metabolism in rainbow trout were investigated. For that, a vegetable oil based diet served as a control diet (C) and was supplemented with 15 g/kg dry matter of biochanin A (BA), daidzein (DA), genistein (G) and equol (EQ), respectively. These five diets were fed to rainbow trout (initial body weight 83.3 ± 0.4 g) for 52 days. Growth performance and nutrient composition of whole body homogenates were not affected by the dietary treatments. Furthermore, feeding EQ to rainbow trout significantly increased DHA levels by +8% in whole body homogenates compared to samples of fish fed the diet C. A tendency towards increased DHA levels in whole body homogenates was found for fish fed the diet G. Fish fed diets BA and DA lacked these effects. Moreover, EQ and G fed fish showed significantly decreased hepatic mRNA steady state levels for fatty acyl desaturase 2a (delta-6) (fads2a(d6)). In contrast, carnitine palmitoyl transferases 1 (cpt1) hepatic mRNA steady state levels and hepatic Fads2a(d6) protein contents were not affected by the dietary treatment. In conclusion, when combined with dietary vegetable oils, equol and genistein seem to stimulate the biosynthesis of DHA and thereby increase tissue DHA levels in rainbow trout, however, only to a moderate extent

Engineering of a functional γ-tocopherol transfer protein

α-tocopherol transfer protein (TTP) was previously reported to self-aggregate into 24-meric spheres (α-TTPS) and to possess transcytotic potency across mono-layers of human umbilical vein endothelial cells (HUVECs). In this work, we describe the characterisation of a functional TTP variant with its vitamer selectivity shifted towards γ-tocopherol. The shift was obtained by introducing an alanine to leucine substitution into the substrate-binding pocket at position 156 through site directed mutagenesis. We report here the X-ray crystal structure of the γ-tocopherol specific particle (γ-TTPS) at 2.24 Å resolution. γ-TTPS features full functionality compared to its α-tocopherol specific parent including self-aggregation potency and transcytotic activity in trans-well experiments using primary HUVEC cells. The impact of the A156L mutation on TTP function is quantified in vitro by measuring the affinity towards γ-tocopherol through micro-differential scanning calorimetry and by determining its ligand-transfer activity. Finally, cell culture experiments using adherently grown HUVEC cells indicate that the protomers of γ-TTP, in contrast to α-TTP, do not counteract cytokine-mediated inflammation at a transcriptional level. Our results suggest that the A156L substitution in TTP is fully functional and has the potential to pave the way for further experiments towards the understanding of α-tocopherol homeostasis in humans

Endogenous n-3 fatty acid synthesis and digestion in rainbow trout Oncorhynchus mykiss are influenced by dietary supplementation of the phytochemicals resveratrol and genistein

Resumen del trabajo presentado al 19th Aquaculture Europe Meeting, celebrado en Berlin (alemania) del 7 al 10 de octubre de 2017.[Introduction]: In order to spare natural marine resources, namely fish oil and fishmeal, a general trend in aquaculture is the dietary inclusion of alternative plant based products. This, however, may lead to decreased nutritional value of the produced fish, especially regarding the fatty acid (FA) composition. Therefore, using phytochemicals in plant based fish feed may be a promising approach to ensure an end product rich in omega-3 (n-3) FA (Trattner et al. 2008; Schiller Vestergren et al. 2012). Resveratrol (RV) and genistein (G) are phytochemicals that, among other modes of action, interact with ∆6-desaturase, a key enzyme in FA synthesis. In two trials, the combined effects of predominantly vegetable diets and dietary RV and G on fish performance, digestion and endogenous FA synthesis were evaluated. [Materials and methods]: In the first feeding trial, rainbow trout (Oncorhynchus mykiss) (36.35±0.03g) were fed nine experimental diets with reduced fish oil levels (F4 = 4%, F2 = 2% and F0 = 0%) and inclusion of either RV (F4+RV, F2+RV and F0+RV) or G (F4+G, F2+G and F0+G) for eight weeks. Analyses were performed based on fish growth, FA composition of fish whole body homogenates, hepatic mRNA levels of ∆6-desaturase, PPARα and target genes, and hepatic ∆6-desaturase protein levels. In the second trial, rainbow trout (144.15±0.06g) were fed again the three experimental diets F0, F0+RV and F0+G for three weeks. Feces were collected by daily stripping of fish and analyzed for macronutrient composition. Additionally, histology of the hind gut was performed at the end of the trial. [Results]: RV and G affected FA composition of whole fish. 20:5 n-3 (EPA) and 22:6 n-3 (DHA) were significantly increased (Figure 1) whereas precursor FA were significantly reduced in fish fed the more vegetable diets F2 and F0 supplemented with RV. At the same time, protein levels of ∆6-desaturase were significantly elevated in fish fed diets supplemented with RV, especially F0+RV. mRNA expression of ∆6-desaturase remained largely unaffected by dietary fish oil inclusion or phytochemical supplementation. Expression of PPARα and the target genes CPT1a and CPT1c were significantly influenced by different dietary fish oil levels only when RV or G was supplemented. In the digestion trial, growth and performance of fish was neither influenced by experimental diet nor supplement type. The apparent digestibility coefficient (ADC) of macronutrients was significantly reduced when dietary G was administered. Additionally, ADC of gross energy was significantly reduced in both feeding groups with supplemented diets (F0+RV and F0+G). Histology of the hindgut revealed no influence of the daily stripping or dietary phytochemical. [Discussion and conclusion]: The combined use of a diet containing 0% fish oil and the supplementation with RV and G revealed positive results concerning fatty acid composition of rainbow trout. EPA and DHA levels were significantly increased when dietary RV was administered which most likely was mediated due to elevated hepatic ∆6-desaturase. Influence of dietary RV and G on mRNA expression of ∆6-desaturase, PPARα and target genes indicates a time or dose dependency of these phytochemicals (Schiller Vestergren et al. 2011). Decreased ADC of especially crude lipid and gross energy in the presence of dietary RV and G are possibly due to antinutritive effects which can be more pronounced at high phytochemical doses (Petrovski et al. 2011). Taken both trials together, there is evidence that both, RV and G, impact lipid metabolism and modulate genes encoding proteins centrally involved in FA synthesis in rainbow trout. This study shows the potential of using especially RV in aquaculture diets low in fish oil. Exact concentrations of the phytochemical used are yet to be determined.Peer Reviewe

Fatty Acid Profile Is Modulated by Dietary Resveratrol in Rainbow Trout (Oncorhynchus mykiss)

To produce fish of a high quality that are rich in omega-3 fatty acids (n-3 FA) and simultaneously generate more sustainable aquaculture, the combined use of phytochemicals and vegetable oils in fish feed seems to be a promising approach. Resveratrol (RV) potentially induces endogenous fatty acid synthesis, resulting in elevated n-3 FA levels in fish. RV putatively influences ∆6-desaturase, the key enzyme in FA metabolism, and serves as a ligand for PPARα, a transcription factor regulating β-oxidation. Rainbow trout (36.35 ± 0.03 g) were randomly allocated into six groups and fed diets with reduced fish oil levels (F4 = 4%, F2 = 2% and F0 = 0% of dry matter) supplemented with 0.3% (w/w) RV (F4 + RV, F2 + RV and F0 + RV). RV significantly affected FA composition in liver tissue and whole fish homogenates. 20:5n-3 (EPA) and 22:6n-3 (DHA) were significantly increased whereas precursor FA were diminished in fish fed the F2 + RV and F0 + RV diets when compared to F4 + RV and F0. RV significantly elevated ∆6-desaturase protein levels in the livers of F0 + RV fed animals. Hepatic mRNA expression of ∆6-desaturase, PPARα, and its target genes were affected by the dietary fish oil level and not by dietary RV. The results of this study indicated a potential benefit of supplementing RV in fish oil deprived diets elevating n-3 FA levels in rainbow trout

Effects of resveratrol and genistein on growth, nutrient utilization and fatty acid composition of rainbow trout

This Article constitutes part of the PhD thesis of Claudia Torno.The replacement of the finite and costly resource fish oil is an important task for aquaculture nutrition. A promising approach could be the use of plant bioactives that may have the potential to influence the metabolism and the synthesis of n-3 long chain polyunsaturated fatty acids, especially EPA (20:5n-3) and DHA (22:6n-3). In this study, the two phytochemicals resveratrol (RV) and genistein (G) were investigated for their effects on fish growth, nutrient utilization and body nutrient composition alongside their effects on whole body fatty acid (FA) composition. In a feeding trial lasting 8 weeks, rainbow trout (initial BW: 81.4±0.5 g) were held in a recirculating aquaculture system and fed six experimental diets with varying fish oil levels as plain variants or supplemented with 0.3% of dry matter (DM) of either RV or G. The six diets were as follows: diet F4 had 4% DM fish oil, diet F0 had 0% DM fish oil, diets F4+RV, F4+G, F0+RV and F0+G were equal to the diets F4 and F0, respectively, and supplemented with the phytochemicals RV and G. The feeding of the F0+RV diet resulted in reduced feed intake, growth rate and slightly reduced whole body lipid levels. At the same time, the amount of polyunsaturated FA and the n-3/n-6 ratio were significantly increased in whole body homogenates of rainbow trout fed diet F0+RV in comparison to the F0 control. The feeding of the F0+G diet led to reduced feed intake, slightly increased protein utilization but did not significantly affect the whole body FA composition. Overall, feeding the fish oil-free diet supplemented with the phytochemicals resulted in more pronounced effects on fish performance and FA composition than the single factors per se (dietary fish oil level or phytochemical). Present data indicate that G might not be of profitable use for trout nutrition. In terms of FA composition, RV could be a potentially useful complement for fish oil. However, the impairment of growth and performance parameters as observed in the present study discourages its use in trout diets.This work was supported by the DFG – Deutsche Forschungsgemeinschaft (grant nos: RI 884/8-1; SCHU 2308/4-1). We are grateful to the Analysis Service Unit facilities of ICTAN for the GC-FID analysis and Spanish Ministerio de Economía, Industria y Competitividad for grant AGL2016-76832-R.Peer reviewe

Fat Quality Impacts the Effect of a High-Fat Diet on the Fatty Acid Profile, Life History Traits and Gene Expression in Drosophila melanogaster

Feeding a high-fat diet (HFD) has been shown to alter phenotypic and metabolic parameters in Drosophila melanogaster. However, the impact of fat quantity and quality remains uncertain. We first used butterfat (BF) as an example to investigate the effects of increasing dietary fat content (3–12%) on male and female fruit flies. Although body weight and body composition were not altered by any BF concentration, health parameters, such as lifespan, fecundity and larval development, were negatively affected in a dose-dependent manner. When fruit flies were fed various 12% HFDs (BF, sunflower oil, olive oil, linseed oil, fish oil), their fatty acid profiles shifted according to the dietary fat qualities. Moreover, fat quality was found to determine the effect size of the response to an HFD for traits, such as lifespan, climbing activity, or fertility. Consistently, we also found a highly fat quality-specific transcriptional response to three exemplary HFD qualities with a small overlap of only 30 differentially expressed genes associated with the immune/stress response and fatty acid metabolism. In conclusion, our data indicate that not only the fat content but also the fat quality is a crucial factor in terms of life-history traits when applying an HFD in D. melanogaster

Does the bioactive resveratrol modulate the fatty acid composition of gilthead sea bream (Sparus aurata)?

Resumen del trabajo presentao al 18th International Symposium on Fish Nutrition and Feeding (ISFNF), celebrado en Las Palmas de Gran Canaria (España) del 3 al 7 de junio de 2018.Possibilities to improve the lipid quality of fish in favor of omega-3 long chain polyunsaturated fatty acids (n-3 LCPUFA) are increasingly important in times of fish oil supply restriction. A promising approach is the use of bioactive phytochemicals with LCPUFA increasing potential in diets of cultured fish. The objective of this study was to evaluate the bioactive resveratrol (RV) and its effects on the marine species gilthead sea bream. A three-factorial approach was chosen to investigate whether effects of RV also depend on dietary fish oil level and temperature of the rearing water. Juvenile gilthead sea bream were fed four different experimental diets over the duration of two months. The diets were formulated to contain two different fish oil levels, 6% DM (F6) and 2% DM (F2). These diets were either supplemented with 0.15% DM resveratrol (+RV) or remained un-supplemented, resulting in four diets (F6, F2, F6+RV, F2+RV). The experiment was carried out in a triplicate approach per dietary treatment, simultaneously at 19 °C and 23 °C rearing temperature. Dietary RV supplementation exhibited none or only minor effects on fish growth, performance and body composition, whereas effects of the rearing temperature and dietary fish oil level were present. Similarly, the fatty acid composition of gilthead sea bream whole body and fillet was rather affected by the rearing temperature and the dietary fish oil level than RV supplementation. In contrast, the liver fatty acid composition was modified by RV supplementation depending on the dietary fish oil level, but only at 19 °C rearing temperature. Most interestingly, the contents of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were increased when fish were fed diet F6+RV in comparison to diet F6, whereas EPA and DHA were decreased in livers of fish fed diet F2+RV in comparison to diet F2. Overall, dietary RV neither had beneficial, nor detrimental effects on fish growth, performance, and fatty acid composition of gilthead sea bream. The modification of EPA and DHA levels in livers of fish held at the low water temperature might indicate possible RV mediated mechanisms affecting fatty acids, which remain to be elucidated.Peer Reviewe

S2 Dataset

Immune-inflammatory response of pigs and macrophages treated with an olive-oil bioactive extract (OBE) and challenged with LP

S4 Dataset

Concentrations of permeability markers in plasma and relative concentrations of CDH1, OCLN, and ZO-1 in the ileal mucosa of pigs challenged chronically with LPS and fed an olive-oil bioactive extract (OBE)