Effects of dietary zinc level on growth performance, lipolysis and expression of genes involved in the calcium/calmodulin-dependent protein kinase kinase-β/AMP-activated protein kinase pathway in juvenile Pacific white shrimp

The present study evaluated the effects of dietary zinc level on growth performance, serum and hepatopancreas metabolites, and expression of genes involved in lipid and energy metabolism, and the signal pathway of dietary Zn-induced lipolysis. Five isonitrogenous and isolipidic diets were formulated to contain different zinc levels: 46.4 (basal diet), 77.2, 87.0, 117.1, and 136.8 mg kg-1, respectively. The results indicated that shrimp fed the diet containing zinc at 117.1 mg kg-1 had higher weight gain and specific growth rate, and the lowest feed intake and feed conversion rate, than shrimp fed the other diets. The deposition rate of Zn in whole body significantly decreased with increasing dietary zinc level. Dietary Zn prevented the accumulation of free radicals and improved antioxidant activities by increasing Cu/Zn superoxide dismutase and reducing malonaldehyde in hepatopancreas. Dietary Zn supplementation enhanced lipase activity and adiponectin, which could promote triglyceride breakdown and fatty acid oxidation and lead to reduced lipid in hepatopancreas. The mRNA expressions of ob-rb, adipor, camkkβ, ampk, cd36, mcd, cpt1 involved in Zn-induced lipid catabolism were up-regulated, and expressions of srebp, acc, fas and scd1 were down-regulated. The mRNA levels of SLC39 family genes (zip3, zip9, zip11, zip14) in hepatopancreas were up-regulated with increasing dietary Zn level. The results demonstrated that dietary Zn level could significantly affect growth performance, tissue deposition of zinc, lipid metabolites and expression of genes involved in lipogenesis and lipolysis in Litopenaeus vannamei

Dietary choline supplementation attenuated high-fat diet-induced inflammation through regulation of lipid metabolism and suppression of NFKB activation in juvenile black seabream (Acanthopagrus schlegelii)

The present study aimed to investigate whether dietary choline can regulate lipid metabolism and suppress NFκB activation and, consequently, attenuate inflammation induced by a high-fat diet in black sea bream (Acanthopagrus schlegelii). An 8-week feeding trial was conducted on fish with an initial weight of 8·16 ± 0·01 g. Five diets were formulated: control, low-fat diet (11 %); HFD, high-fat diet (17 %); and HFD supplemented with graded levels of choline (3, 6 or 12 g/kg) termed HFD + C1, HFD + C2 and HFD + C3, respectively. Dietary choline decreased lipid content in whole body and tissues. Highest TAG and cholesterol concentrations in serum and liver were recorded in fish fed the HFD. Similarly, compared with fish fed the HFD, dietary choline reduced vacuolar fat drops and ameliorated HFD-induced pathological changes in liver. Expression of genes of lipolysis pathways were up-regulated, and genes of lipogenesis down-regulated, by dietary choline compared with fish fed the HFD. Expression of nfκb and pro-inflammatory cytokines in liver and intestine was suppressed by choline supplementation, whereas expression of anti-inflammatory cytokines was promoted in fish fed choline-supplemented diets. In fish that received lipopolysaccharide to stimulate inflammatory responses, the expression of nfκb and pro-inflammatory cytokines in liver, intestine and kidney were all down-regulated by dietary choline compared with the HFD. Overall, the present study indicated that dietary choline had a lipid-lowering effect, which could protect the liver by regulating intrahepatic lipid metabolism, reducing lipid droplet accumulation and suppressing NFκB activation, consequently attenuating HFD-induced inflammation in A. schlegelii

Influence of dietary zinc on growth, zinc bioaccumulation and expression of genes involved in antioxidant and innate immune in juvenile mud crabs (Scylla paramamosain)

The aim of present study was to investigate the effects of dietary Zn level on growth performance, Zn bioaccumulation, antioxidant capacity and innate immunity in juvenile mud crab (Scylla paramamosain). Six semi-purified diets were formulated to contain dietary Zn levels of 44.5, 56.9, 68.5, 97.3, 155.6 or 254.7 mg·kg-1, respectively. Dietary Zn level significantly influenced percent weight gain (PWG), with highest observed in crab fed the diet containing 97.3 mg·kg-1 Zn. Tissue Zn concentrations significantly increased as dietary Zn levels increased from 44.5 to 254.7 mg·kg-1. Retention of Zn in hepatopancreas increased with dietary Zn levels up to 68.5 mg·kg-1 and then significantly decreased. Moreover, inadequate dietary Zn (44.5 and 56.9 mg·kg-1) reduced anti-oxidation markers including total superoxide dismutase and copper/zinc superoxide dismutase activities and total anti-oxidant level. Crabs fed the diet with 44.5 mg·kg-1 Zn also showed significantly lower expression of genes involved in antioxidant status, such as Cu/Zn sod, glutathione peroxidase, catalase and thioredoxin than those fed diets containing 68.5 and 97.3 mg·kg-1 Zn. Highest activities of phenoloxidase and alkaline phosphatase were recorded in crab fed the diets containing 68.5 and 97.3 mg·kg-1 Zn. Expression levels of prophenoloxidase and toll-like receptor 2 were higher in crab fed the 97.3 mg·kg-1 Zn diet compared to crab fed the other diets. Based on PWG alone, the optimal dietary Zn level was estimated to be 82.9 mg·kg-1, with 68.5 to 97.3 mg·kg-1 recommended for maintaining optimal Zn bioaccumulation, oxidation resistance and innate immune response of juvenile mud crab

Effects of dietary lipid level on growth, fatty acid profiles, antioxidant capacity and expression of genes involved in lipid metabolism in juvenile swimming crab, Portunus trituberculatus

The regulation of lipogenesis and lipolysis mechanisms related to consumption of lipid has not been studied in swimming crab. The aims of present study were to evaluate the effects of dietary lipid levels on growth, enzymes activities, and expression of genes of lipid metabolism in hepatopancreas of juvenile swimming crab. Three isonitrogenous diets were formulated to contain crude lipid levels at 5.8 %, 9.9 % and 15.1 %, respectively. Crabs fed the diet containing 15.1 % lipid had significantly lower weight gain, specific growth rate and survival, and higher feed conversion ratio than those fed the 5.8 % and 9.9 % lipid diets. Crabs fed 5.8 % lipid had lower malondialdehyde concentrations in the hemolymph and hepatopancreas than those fed the other diets. Highest glutathione peroxidase in hemolymph and superoxide dismutase in hepatopancreas were observed in crabs fed 5.8 % lipid. The lowest fatty acid synthase and glucose 6-phosphate dehydrogenase activities in hepatopancreas were observed in crabs fed 15.1 % lipid, whereas crabs fed 5.8 % lipid had lower carnitine palmitoyltransferase-1 activity than those fed the other diets. Crabs fed 15.1 % lipid showed lower hepatopancreas expression of genes involved in LC-PUFA biosynthesis, lipoprotein clearance, fatty acid uptake, fatty acid oxidation, lipid anabolism and lipid catabolism than those fed the other diets, whereas expression of some genes of lipoprotein assembly and fatty acid oxidation were up-regulated compared with crabs fed 5.8 % lipid. Overall, high dietary lipid level can inhibit growth, reduce feed utilization and reduce antioxidant enzyme activities. Moreover, dietary lipid influenced enzyme activities and gene expression involved in lipid metabolism of juvenile swimming crab

Modification of nutritional values and flavor qualities of muscle of swimming crab (Portunus trituberculatus): Application of a dietary lipid nutrition strategy

Lipid sources as alternatives to fish oil could alter the nutritional value and flavor quality of crab meat affecting consumer preferences. Herein, an 8-week nutritional trial was designed to investigate the effects of dietary lipid sources including fish oil (FO), krill oil (KO), palm oil, rapeseed oil, soybean oil and linseed oil on profiles of amino acids, fatty acids and volatiles in muscle of swimming crab (Portunus trituberculatus). Volatiles of crab muscle were characterized by headspace solid-phase microextraction and gas chromatography-tandem mass spectrometry. Results revealed that crabs fed FO and KO had significantly higher levels of protein, indispensable amino acids, eicosapentaenoic acid and docosahexaenoic acid in muscle. Principal component analysis and hierarchical cluster analysis demonstrated that muscle volatiles of crabs fed different dietary oils exhibited significant variations. Dietary FO and KO significantly increased the relative levels of 3-methylbutanal, heptanal, benzaldehyde and nonanal in muscle, which may produce more pleasant flavors

Transcriptomic and physiological analyses of hepatopancreas reveal the key metabolic changes in response to dietary copper level in Pacific white shrimp Litopenaeus vannamei

All living organisms require copper for growth and development, but the gene expression profiles and molecular mechanisms underpinning dietary copper are poorly investigated. Therefore, the present study aimed to determine the potential metabolic changes in response to dietary copper based on analysis of hepatopancreas transcriptome in Litopenaeus vannamei. Three practical diets were formulated to supplement 0 (control diet; Csingle bondCu) and 40 mg kg−1 inorganic Cu (CuSO4·5H2O; Isingle bondCu) and copper amino acid chelate (Osingle bondCu), with analyzed Cu being 12.4, 49.8 and 50.0 mg kg−1, respectively. Shrimp fed Isingle bondCu and Osingle bondCu diets had higher percent weight gain and Cu concentration in tissues. Some essential amino acids (lysine, methionine, isoleucine, leucine, valine) and non-essential amino acids (tyrosine, glycine, aspartic acid, proline and serine) in hepatopancreas significantly increased in shrimp fed the copper supplemented diets. Transcriptome analysis indicated a total of 742 and 912 genes were differentially expressed (q < 0.001; log2fold change ≥2) in shrimp fed the Isingle bondCu and Osingle bondCu diets, respectively, in comparison to shrimp fed the control diet. Five and eight significantly changed pathways were annotated in the Csingle bondCu vs. Isingle bondCu and Csingle bondCu vs. Osingle bondCu comparisons, with metabolism the leading category for both. Similarly, the proportion of differentially expressed genes revealed that most were enriched in the category of metabolism. Further analysis revealed that dietary copper mainly affected amino acid and glycerophospholipid metabolism. Moreover, two significantly changed pathways (phagosome and IL-17 signaling pathway) related to the immune system were identified in shrimp fed the Osingle bondCu diet. The present study analyzing the hepatopancreas transcriptome identified potential roles of dietary copper on amino acid and glycerophospholipid metabolism and provided new insight that will be valuable in future studies to further elucidate the nutritional molecular basis of copper

Dietary DHA/EPA ratio affects growth, tissue fatty acid profiles and expression of genes involved in lipid metabolism in mud crab Scylla paramamosain supplied with appropriate n-3 LC-PUFA at two lipid levels

An 8-week feeding trial was conducted to determine the optimal dietary docosahexaenoic acid/eisosapentaenoic acid (DHA/EPA) ratio of mud crab (Scylla paramamosain) supplied with optimal n-3 LC-PUFA at two dietary lipid levels. Eight isonitrogenous diets were formulated to contain 7% and 12% crude lipid, each with DHA/EPA ratios of 0.6, 1.2, 2.3 and 3.2, respectively. Each diet was randomly assigned to triplicate groups of 30 juvenile mud crabs (initial weight 20.9 ± 0.6g) that were stocked in single crab cells. In crabs fed 7% lipid, the diet with a DHA/EPA ratio of 2.3 showed significantly higher weight gain than crabs fed the other ratios while in crabs fed 12% lipid, lower weight gain and specific growth rate were observed in crabs fed the diet with a DHA/EPA ratio of 0.6 than crabs fed the other ratios. Lipid content in hepatopancreas significantly increased as dietary DHA/EPA ratio increased from 1.2 to 2.3 in crabs fed 7% lipid, while no differences were observed among crabs fed the diets with DHA/EPA ratios higher than 0.6 when fed 12% lipid. Total fatty acid and DHA contents and DHA/EPA ratio showed increasing, and EPA decreasing, trends in muscle and hepatopancreas with increased dietary DHA/EPA ratio, at both dietary lipid levels. The hemolymph triacylglycerol and total cholesterol contents were higher in crabs fed dietary DHA/PA ratios of 1.2 and 2.3 than those fed ratios of 0.6 and 3.2 at 7% dietary lipid, and lowest low and high-density lipoprotein cholesterol contents were observed in crabs fed DHA/EPA dietary ratios of 0.6 and 3.2 at 7% and 12% lipid, respectively. The expression levels of fas, aco3 and fatp4 were significantly up-regulated, and cptⅠ, hsl and ldlr were down-regulated, with increased dietary DHA/EPA ratio in crabs fed 7% lipid. In crabs fed 12% lipid, the expression levels of g6pd, 6pgd, srebp-1, aco1 and fatp4 were down-regulated, and fabp-1 was up-regulated, with increased dietary DHA/EPA ratio. The expression levels of elovl4 and Δ6 fad initially increased and then decreased as dietary DHA/EPA ratio increased from 0.6 to 3.2 in crabs fed both 7% and 12% lipid. Based on analysis of weight gain versus dietary DHA/EPA ratio, the optimal dietary DHA/EPA ratios of mud crab S. paramamosa were estimated to be 2.2 and 1.2 when supplied with optimal n-3 LC-PUFA at 7% and 12% lipid, respectively

Dietary Betaine Mitigates Hepatic Steatosis and Inflammation Induced by a High-Fat-Diet by Modulating the Sirt1/Srebp-1/Pparɑ Pathway in Juvenile Black Seabream (Acanthopagrus schlegelii)

The present study aimed to elucidate the mechanism of dietary betaine, as a lipid-lowering substance, on the regulation of lipid metabolism and inflammation in juvenile black seabream (Acanthopagrus schlegelii) fed a high fat diet. An 8-week feeding trial was conducted in black seabream with an initial weight of 8.39 ± 0.01g fed four isonitrogenous diets including Control, medium-fat diet (11%); HFD, high-fat diet (17%); and HFD supplemented with two levels (10 and 20 g/kg) of betaine, HFD+B1 and HFD+B2, respectively. SGR and FE in fish fed HFD+B2 were significantly higher than in fish fed HFD. Liver histology revealed that vacuolar fat droplets were smaller and fewer in bream fed HFD supplemented with betaine compared to fish fed HFD. Betaine promoted the mRNA and protein expression levels of silent information regulator 1 (Sirt1), up-regulated mRNA expression and protein content of lipid peroxisome proliferator-activated receptor alpha (pparα), and down-regulated mRNA expression and protein content of sterol regulatory element-binding protein-1(srebp-1). Furthermore, the mRNA expression levels of anti-inflammatory cytokines in liver and intestine were up-regulated, while nuclear factor kB (nf-kb) and pro-inflammatory cytokines were down-regulated by dietary betaine supplementation. Likewise, in fish that received lipopolysaccharide (LPS) to stimulate inflammatory responses, the expression levels of mRNAs of anti-inflammatory cytokines in liver, intestine and kidney were up-regulated in fish fed HFD supplemented with betaine compared with fish fed HFD, while nf-kb and pro-inflammatory cytokines were down-regulated. This is the first report to suggest that dietary betaine could be an effective feed additive to alleviate hepatic steatosis and attenuate inflammatory responses in black seabream fed a high fat diet by modulating the Sirt1/Srebp-1/Pparɑ pathway

Dietary lipid and n-3 long-chain PUFA levels impact growth performance and lipid metabolism of juvenile mud crab, Scylla paramamosain

An 8 weeks feeding trial was conducted to evaluate the effects of dietary n-3 LC-PUFA levels on growth performance, tissue fatty acid profiles and relative expression of genes involved in lipid metabolism of mud crab (Scylla paramamosain). Ten isonitrogenous diets were formulated to contain five n-3 LC-PUFA levels at 7 % and 12 % dietary lipid levels. Highest weight gain and specific growth rate were observed in crabs fed the diets with 19.8 and 13.2 mg g-1 n-3 LC-PUFA at 7 % and 12 % lipid, respectively. Moisture and lipid contents in hepatopancreas and muscle were significantly influenced by dietary n-3 LC-PUFA at the two lipid levels. The DHA, EPA, n-3 LC-PUFA contents and n-3/n-6 PUFA ratio in hepatopancreas and muscle significantly increased as dietary n-3 LC-PUFA levels increased at both lipid levels. The expression levels of Δ6 FAD and ACO in hepatopancreas increased significantly, and expression levels of FAS, CPTⅠ and HSL were down-regulated, with increased dietary n-3 LC-PUFA regardless of lipid level. Based on weight gain, the n-3 LC-PUFA requirements of S. paramamosain were estimated to be 20.1 mg g-1 and 12.7 mg g-1 of diet at 7 % and 12 % dietary lipid, respectively. Over all, dietary lipid level influenced lipid metabolism, and purified, high-lipid diets rich in palmitic acid reduced the n-3 LC-PUFA requirement of juvenile mud crab

Dietary organic zinc promotes growth, immune response and antioxidant capacity by modulating zinc signaling in juvenile Pacific white shrimp (Litopenaeus vannamei)

An 8-week feeding trial was conducted to evaluate effects of dietary organic zinc (zinc amino acid chelate) on growth performance, mineral bioaccumulation in whole body, hepatopancreas and carapace, innate immune response and antioxidant capacity of juvenile Pacific white shrimp Litopenaeus vannamei. Five isonitrogenous and isolipidic diets were formulated to contain different zinc levels of 46.4 (basal diet), 65.5, 85.9, 108.4 and 130.6 mg kg−1. Dietary zinc level significantly influenced growth and feed utilization, with the lowest weight gain and highest feed conversion ratio observed in shrimp fed the basal diet. The optimal dietary zinc requirement was estimated to be 104.8 mg kg-1 for juvenile Pacific white shrimp. Shrimp fed the diet containing 130.6 mg kg−1 Zn had the highest zinc concentration in hepatopancreas and carapace, but there were no significant differences in calcium or phosphorus concentration in tissues. Dietary Zn increased the activities of lysozyme, alkaline phosphatase and polyphenol oxidase in hepatopancreas. Shrimp fed the diets supplemented with zinc had significantly higher activity of Cu/Zn SOD and lower content of malondialdehyde in hepatopancreas. The expression levels of toll, imd, lzm, proPO and alp involved in immunity and Cu/Zn sod related to oxidation resistance were up-regulated. Zinc also promoted the expression levels of mt and mtf-1, and up-regulated the expression of SLC39 family genes (zip3, zip9, zip11, zip14) in hepatopancreas. These data provided novel insights in the potential mechanism of organic zinc-induced enhancement of immunity and antioxidant capacity in Pacific white shrimp