Muscle Lipid Content Research Articles

Effects of an alternating linseed oil-fish oil feeding strategy on growth, fatty acid restoration and expression of lipid related genes in black seabream (A. schlegelii)

An eight-week feeding trial was conducted to evaluate the influence of an alternating linseed oil (LO) and fish oil (FO) feeding strategy in black seabream A. schlegelii (initial weight, 8.49 ± 0.01 g). Two isonitrogenous and isolipidic feeds were formulated to contain FO or LO, and used to enable three feeding strategy treatments termed FO (feeding the FO diet for 8 weeks), LO (feeding the LO diet for 8 weeks) and FO re-feeding (feeding LO for 4 weeks then FO for 4 weeks). Fish in the FO re-feeding and FO groups had significantly higher final body weights (FBW), weight gains (WG), specific growth rates (SGR) but lower muscle lipid content than fish in the LO group. In muscle, the FO re-feeding strategy restored eicosapentaenoic and docosahexaenoic acid contents to 82.67% and 83.84%, respectively, of those in fish fed the FO treatment. In addition, the FO re-feeding strategy significantly down-regulated the expression levels of genes related to long-chain polyunsaturated fatty acid (LC-PUFA) biosynthesis and lipogenesis, including fatty acyl desaturase (fads2), elongase of very long-chain fatty acids 4a (elovl4a) and sterol regulatory element-binding protein-1 (srebp-1) compared to fish fed the LO treatment. Similarly, the hepatic Srebp-1c concentration in fish in the FO re-feeding group was markedly lower than in fish in the LO treatment group. Expression of the lipid catabolism gene adipose triglyceride lipase (atgl) was up-regulated in fish in the FO re-feeding group compared with fish in the LO group. Overall, the present study indicated that a strategy of re-feeding FO following feeding LO for four-week promoted growth, mitigated lipid accumulation in muscle, and effectively restored muscle n-3 LC-PUFA levels in A. schlegelii.

Effect of lipid sources on growth performance, muscle composition, haemolymph biochemical indices and digestive enzyme activities of red swamp crayfish ( Procambarus clarkii )

This study was conducted to determine the effects of different dietary lipid sources on red swamp crayfish (Procambarus clarkii). Six diets were formulated with the same lipid level (85 g/kg) to contain fish oil (FO), soybean oil (SO), corn oil (CO), palm oil (PO), lecithin oil (LO) and pork lard (PL) respectively. Each diet was fed to triplicate of 18 crayfish with an initial weight of (13.05 ± 0.60) g for 8 weeks. The results showed that crayfish fed diet SO had a significantly higher weight gain rate and specific growth rate than those fed diet CO, PO and PL, but there was no significant difference among crayfish fed diet FO, SO and LO. Crayfish fed diet PL had the highest feed conversion ratio and the lowest survival rate. Significantly increased muscle lipid contents were observed in groups PO and PL compared with other groups. Group FO had the highest values of EPA, DHA and n-3/n-6 ratio in muscle, followed by groups LO and SO. The haemolymph triacylglycerol content was the highest, whereas alkaline phosphatase activity was the lowest in crayfish fed diet PL. Moreover, a significant increase of total protein content was observed in the haemolymph of crayfish fed diet FO, SO and LO. In conclusion, crayfish fed diet FO, SO and LO showed better growth than those fed diet PL and PO without any signs of essential fatty acid deficiency.

Genomic and Phenotypic Agreement Defines the Use of Microwave Dielectric Spectroscopy for Recording Muscle Lipid Content in European Seabass (Dicentrarchus labrax).

Recording the fillet lipid percentage in European seabass is crucial to control lipid deposition as a means toward improving production efficiency and product quality. The reference method for recording lipid content is solvent lipid extraction and is the most accurate and precise method available. However, it is costly, requires sacrificing the fish and grinding the fillet sample which limits the scope of applications, for example grading of fillets, recording live fish or selective breeding of fish with own phenotypes are all limited. We tested a rapid, cost effective and non-destructive handheld microwave dielectric spectrometer (namely the Distell fat meter) against the reference method by recording both methods on 313 European seabass (Dicentrarchus labrax). The total method agreement between the dielectric spectrometer and the reference method was assessed by Lin’s concordance correlation coefficient (CCC), which was low to moderate CCC = 0.36–0.63. We detected a significant underestimation in accuracy of lipid percentage 22–26% by the dielectric spectrometer and increased imprecision resulting in the coefficient of variation (CV) doubling for dielectric spectrometer CV = 40.7–46% as compared to the reference method 27–31%. Substantial genetic variation for fillet lipid percentage was found for both the reference method (h2 = 0.59) and dielectric spectroscopy (h2 = 0.38–0.58), demonstrating that selective breeding is a promising method for controlling fillet lipid content. Importantly, the genetic correlation (rg) between the dielectric spectrometer and the reference method was positive and close to unity (rg = 0.96), demonstrating the dielectric spectrometer captures practically all the genetic variation in the reference method. These findings form the basis of defining the scope of applications and experimental design for using dielectric spectroscopy for recording fillet lipid content in European seabass and validate its use for selective breeding.

Dietary zinc levels affects lipid and fatty acid metabolism in hepatopancreas of mud crab (Scylla paramamosain)

This study investigated the influences of dietary zinc (Zn) on lipid and fatty acid metabolism of Scylla paramamosain. Three diets containing analyzed Zn levels including 44.5 (low Zn), 68.5 (medium Zn) and 254.7 (high Zn) mg/kg were prepared and fed to mud crab for 10 weeks, respectively. Medium dietary Zn levels improved the growth of mud crab than those fed the high Zn diet. The concentration of Zn in tissues was positively correlated with dietary Zn levels. Crabs fed with high Zn diet significantly decreased lipid content in hepatopancreas and muscle when compared to those fed the medium Zn diet. The lowest diameter, area and number of R cell in hepatopancreas histology were observed in those fed the high Zn diet. Furthermore, medium levels of dietary Zn significantly increased docosahexaenoic acid (DHA) and n-3 polyunsaturated fatty acid (PUFA) contents in hepatopancreas. Crabs fed high Zn diet dramatically down-regulated expression of acc, fas, g6pd, 6pgd and srebp, but up-regulated expression of aco3, cpt1 and fabp1 in hepatopancreas. Crabs fed with medium Zn diet significantly increased the mRNA levels of fad in hepatopancreas. In summary, the results of present study emphasized the adverse effects of excess dietary Zn (254.7 mg/kg) on suppress hepatopancreatic lipid and n-3 PUFA accumulation, dietary 68.5 mg/kg Zn level was recommended to maintain optimal lipid and fatty acid metabolism of mud crab.

Effects of Dietary Protein and Lipid Levels on Growth, Body Composition, Blood Biochemistry, Antioxidant Capacity and Ammonia Excretion of European Grayling (Thymallus thymallus)

This study evaluated growth, body composition, antioxidant capacity, innate immunity and ammonia excretion of European grayling (Thymallus thymallus) fed diets containing different protein and lipid contents. Six diets were produced to contain 30, 40, or 50% protein and 10 or 20% lipid. Juvenile fish averaging 25.2 ± 0.28 g were stocked into eighteen 450-L circular tanks in a recirculating aquaculture system (RAS) and fed the test diets to satiation twice daily for 12 weeks. Fish weight gain (WG) was enhanced (P < 0.05) as dietary protein increased from 30% (229% WG) to 40% (262% WG) and plateaued thereafter. Enhancing protein and lipid content of diet led to reduced feed intake. Also, feed efficiency was improved by increasing dietary protein (by 40.8%) and lipid (by 16.5%) levels. An interaction of protein and lipid was found on whole-body lipid, and muscle lipid content increased as dietary lipid level increased. Muscle arachidonic acid (ARA), eicosapentaenoic acid (EPA, 20:5n-3) and total n-6 long-chain polyunsaturated fatty acids (LC-PUFA) contents enhanced by increasing dietary protein level. Moreover, increasing fat content of diet led to enhanced muscle linoleic acid, linolenic acid, total monounsaturated fatty acids (MUFA), total n-6, ratio of docosahexaenoic acid (DHA, 22:6n-3) to EPA and n-6/n-3. However, EPA, DHA, total n-6 LC-PUFA, total n-3, total n-3 LC-PUFA, and EPA/ARA ratio decreased at higher dietary lipid level. Serum triglyceride (TG) level and lactate dehydrogenase (LDH) activity decreased as dietary protein level increased. Increasing fat content of diet led to enhanced serum TG, cholesterol and glucose concentrations and reduced alanine aminotransferase, aspartate amino transferase and LDH activities. Serum malondialdehyde concentration was enhanced by increasing both dietary protein and lipid. Furthermore, serum myeloperoxidase activity was enhanced at higher dietary lipid level. Water ammonium nitrogen (NH4+-N) concentration was measured after 5 and 24 h of last feeding, and the results indicated the reduction of ammonia excretion as dietary lipid content increased. These findings suggest that 40% dietary protein can support optimal growth of juvenile European grayling reared in RAS and increasing lipid content from 10 to 20% can improve feed utilization and reduce ammonia excretion to the rearing water.

Optimizing the fatty acid profile of novel terrestrial oil blends in low fishmeal diets of rainbow trout (Oncorhynchus mykiss) yields comparable fish growth, total fillet n-3 LC-PUFA content, and health performance relative to fish oil

Identifying and effectively utilizing suitable, novel, terrestrial oil sources either alone or as blends to replace fish oil (FO) is a prerequisite for improving the sustainability of global aquaculture. Therefore, the present study evaluates several novel terrestrial oil blends (TOBs), optimized for their fatty acid profile, as alternatives to FO in low fishmeal diets fed to rainbow trout (Oncorhynchus mykiss) and describes the subsequent effects on fish growth, fatty acid composition and health. Insect oil (IO), genetically modified canola oil (CO), palm oil (PO) and linseed oil (LO) were used for the formulation of three TOBs viz., TOB-1 (30%IO+36%CO + 34%LO), TOB-2 (40%PO + 20%CO + 40%LO) and TOB-3 (50%TOB-1 + 50%TOB-2). Formulas TOB-1 and TOB-2 considered the total fatty acid profile based upon the general FO fatty acid profile, published fatty acid research for rainbow trout, and the fatty acid requirements of rainbow trout. A low fishmeal based basal diet containing 44% crude protein was formulated, and FO, TOB-1, TOB-2 and TOB-3 were incorporated in the basal diet to prepare the experimental diet groups, Control, TOB-1, TOB-2 and TOB-3, respectively. All experimental diets were fed to triplicate groups of rainbow trout juveniles (initial weight 7.9 ± 0.02 g) for 9 weeks. Growth performance (final weight, percent weight gain and specific growth rate) in TOBs fed groups were equal to the FO-based control group. Fish fed the TOB-3 diet consumed more feed followed by the control and TOB-1 diet groups. Significantly lower feed intake was observed in the TOB-2 diet group. Feed conversion ratio and protein efficiency ratio were not significantly influenced by dietary oil sources. Fish fed the control diet showed significantly higher hepatic lipid content compared to TOB groups, followed by TOB-2, TOB-3, and TOB-1, which was significantly lower in hepatic lipid content. Muscle lipid content and whole-body major nutrient compositions were not significantly influenced by the dietary oil sources. Fatty acid composition of muscle and liver reflected that of the diets. Maximum values for n3 LC-PUFAs (EPA and DHA), lauric acid (C12:0) and C18:3n-3 were observed in the FO, TOB-1 and TOB-2 groups, respectively. Except for C12:0, muscle saturated fatty acid contents were significantly lower in TOBs-based diet compared to the FO-based control diet fish. As expected, muscle C12:0 content was significantly higher in the TOB-1 group followed by the TOB-3 group. TOB-2 and control groups had significantly lower content of C12:0. The fillet total n-3 LC-PUFA was significantly higher in fish fed the control diet group followed by TOB-3 and TOB-2 groups, TOB-1 showed significantly lower content of total n-3 LC- PUFA. Hepatic delta-5 desaturase (Δ5fad), delta-6 desaturase (Δ 6fad) and fatty acid elongase-2 (Elovl-2) gene expressions were significantly influenced by dietary oil sources, where TOB-based groups showed higher Δ6fad and Elovl-2 expressions. Measured innate immunity and antioxidant markers were not affected by TOBs. Finally, we concluded that TOBs could serve as a substitute for FO in rainbow trout feed without negatively impacting performance. Moreover, fillet total n-3 LC-PUFA of TOB-fed fish satisfies the suggested daily serving for humans.

Effects of dietary inorganic phosphorus levels on growth, liver and intestinal morphology and digestive enzymes in fingerling obscure puffer (Takifugu obscurus)

Phosphorus (P) is involved in extensive metabolism and fish attain most of P from their diets. However, little is known about the optimal supplemented amount of P in diet for Takifugu obscurus (obscure puffer). To explore the effects of P on growth performance, tissues mineralization, digestive organs structure, and digestive capability, six diets supplemented with at 0, 2, 4, 6, 8 and 12 g/kg P were prepared and fed to obscure puffer (11.92 ± 0.19 g) for 56 days. The results showed that the highest final body weight, specific weight gain rate and protein efficiency ratio were observed in puffer fed diet supplemented with 6, 8 and 12 g/kg P. Dietary inorganic P supplements markedly increased P and calcium concentrations of the whole-body, muscle and vertebrae. The crude lipid content of whole body and muscle, plasma cholesterol and triglyceride content were reduced with increasing inorganic P supplement. For digestive capability, hepatic and intestinal structure and villi length of intestine were also significantly improved in puffer fed 6, 8 and 12 g/kg inorganic P diet. Moreover, hepatic and intestinal lipase activities were significantly enhanced in fish with raising inorganic P supplement in diet. Hepatic and intestinal amylase activities were markedly increased in puffer fed 8 g/kg inorganic P diet. The present study indicated that optimal dietary inorganic P level could promote growth by improving liver and intestinal morphology, vertebrae mineral deposition and increasing digestive capability in obscure puffer, which suggested that the range of supplemental inorganic P is estimated to be 4.5–6.4 g/kg based on the broken-line analysis of whole body and vertebrae P content.

ФИЗИОЛОГО-БИОХИМИЧЕСКИЕ ИЗМЕНЕНИЯ КАСПИЙСКОЙ ОБЫКНОВЕННОЙ КИЛЬКИ (CLUPEONELLA DELICATULA CASPIA SVETOVIDOV) В РАЗЛИЧНЫЕ ПЕРИОДЫ ГОДОВОГО ЦИКЛА

The article considers studying the physiological and biochemical parameters of the common sprat (Clupeonella delicatula caspia Svetovidov) taken in the western part of the Middle Caspian Sea at different periods of the annual cycle. There were studied the species in the pre-spawning state, at the beginning of spawning, at the feeding stage and at the pre-wintering stage. 
 In fish muscle tissue the content of water-soluble protein and total lipids was determined. In the pre-spawning period, in male common sprat was recorded a positive correlation (p < 0.05) between the weight of fishes, fishing length and content of total lipids in muscles (r = +0.5206) and (r = +0.5039), respectively. In females no statistically significant dependence of the size-weight parameters and lipid content in muscles were recorded, which is probably due to the fact that lipids in their bodies were spent for energy needs, and to a greater extent than in males - for the generative function. In a comparative aspect, in the muscles of males and females no significant differences in the content of total lipids and water-soluble protein in the pre-spawning period were found. At the stage of the beginning of spawning, a decrease in total lipids and water-soluble protein was noted in the muscle tissue of the studied fishes, which is associated with an increase in energy consumption for sweeping out sexual products. During the feeding period the common sprat was characterized by an intensive accumulation of lipid reserves; the content of total lipids and water-soluble protein in the muscles increased with increasing length of individuals. In the pre-winter period stabilization of muscle lipid and increase in protein reserves were recorded, which is necessary for fish to ensure a normal existence 
 in the subsequent stages of the annual cycle.

Feeding habitat and silvering stage affect lipid content and fatty acid composition of European eel Anguilla anguilla tissues.

Lipids, particularly fatty acids (FAs), are major sources of energy and nutrients in aquatic ecosystems and play key roles during vertebrate development. The European eel Anguilla anguilla goes through major biochemical and physiological changes throughout its lifecycle as it inhabits sea- (SW), and/or brackish- (BW) and/or freshwater (FW) habitats. With the ultimate goal being to understand the reasons for eels adopting a certain life history strategy (FW or SW residency vs. 'habitat shifting'), we explored differences in lipid content and FA composition of muscle, liver and eyes from eels collected across Norwegian SW, BW and FW habitats, and at different lifecycle stages (yellow to silver). FW and SW eels had a higher lipid content overall compared to BW eels, reflecting differences in food availability and life history strategies. SW eels had higher proportions of certain monounsaturated FAs (MUFAs; 18:1n-9, 20:1n-9), and of the essential polyunsaturated FAs 20:5n-3 (eicosapentaenoic acid, EPA) and 22:6n-3 (docosahexaenoic acid) than FW eels, reflecting a marine-based diet. In contrast, the muscle of FW eels had higher proportions of 18:3n-3, 18:2n-6 and 20:4n-6 (arachidonic acid), as is typical of FW organisms. MUFA proportions increased in later stage eels, consistent with the hypothesis that the eels accumulate energy stores prior to migration. In addition, the decrease of EPA with advancing stage may be associated with the critical role that this FA plays in eel sexual development. Lipid and FA information provided further understanding of the habitat use and overall ecology of this critically endangered species.

Mitochondrial Adaptation to Diet and Swimming Activity in Gilthead Seabream: Improved Nutritional Efficiency.

Sustained exercise promotes growth in different fish species, and in gilthead seabream we have demonstrated that it improves nutrient use efficiency. This study assesses for differences in growth rate, tissue composition and energy metabolism in gilthead seabream juveniles fed two diets: high-protein (HP; 54% protein, 15% lipid) or high energy (HE; 50% protein, 20% lipid), under voluntary swimming (VS) or moderate-to-low-intensity sustained swimming (SS) for 6 weeks. HE fed fish under VS conditions showed lower body weight and higher muscle lipid content than HP fed fish, but no differences between the two groups were observed under SS conditions. Irrespective of the swimming regime, the white muscle stable isotopes profile of the HE group revealed increased nitrogen and carbon turnovers. Nitrogen fractionation increased in the HP fed fish under SS, indicating enhanced dietary protein oxidation. Hepatic gene expression markers of energy metabolism and mitochondrial biogenesis showed clear differences between the two diets under VS: a significant shift in the COX/CS ratio, modifications in UCPs, and downregulation of PGC1a in the HE-fed fish. Swimming induced mitochondrial remodeling through upregulation of fusion and fission markers, and removing almost all the differences observed under VS. In the HE-fed fish, white skeletal muscle benefited from the increased energy demand, amending the oxidative uncoupling produced under the VS condition by an excess of lipids and the pro-fission state observed in mitochondria. Contrarily, red muscle revealed more tolerant to the energy content of the HE diet, even under VS conditions, with higher expression of oxidative enzymes (COX and CS) without any sign of mitochondrial stress or mitochondrial biogenesis induction. Furthermore, this tissue had enough plasticity to shift its metabolism under higher energy demand (SS), again equalizing the differences observed between diets under VS condition. Globally, the balance between dietary nutrients affects mitochondrial regulation due to their use as energy fuels, but exercise corrects imbalances allowing practical diets with lower protein and higher lipid content without detrimental effects.

The Effect of Obstructive Sleep Apnea and Continuous Positive Airway Pressure Therapy on Skeletal Muscle Lipid Content in Obese and Nonobese Men.

Obstructive sleep apnea (OSA), independently of obesity (OBS), predisposes to insulin resistance (IR) for largely unknown reasons. Because OSA-related intermittent hypoxia triggers lipolysis, overnight increases in circulating free fatty acids (FFAs) including palmitic acid (PA) may lead to ectopic intramuscular lipid accumulation potentially contributing to IR. Using 3-T-1H-magnetic resonance spectroscopy, we therefore compared intramyocellular and extramyocellular lipid (IMCL and EMCL) in the vastus lateralis muscle at approximately 7 am between 26 male patients with moderate-to-severe OSA (17 obese, 9 nonobese) and 23 healthy male controls (12 obese, 11 nonobese). Fiber type composition was evaluated by muscle biopsies. Moreover, we measured fasted FFAs including PA, glycated hemoglobin A1c, thigh subcutaneous fat volume (ScFAT, 1.5-T magnetic resonance tomography), and maximal oxygen uptake (VO2max). Fourteen patients were reassessed after continuous positive airway pressure (CPAP) therapy. Total FFAs and PA were significantly (by 178% and 166%) higher in OSA patients vs controls and correlated with the apnea-hypopnea index (AHI) (r ≥ 0.45, P < .01). Moreover, IMCL and EMCL were 55% (P < .05) and 40% (P < .05) higher in OSA patients, that is, 114% and 103% in nonobese, 24.4% and 8.4% in obese participants (with higher control levels). Overall, PA, FFAs (minus PA), and ScFAT significantly contributed to IMCL (multiple r = 0.568, P = .002). CPAP significantly decreased EMCL (–26%) and, by trend only, IMCL, total FFAs, and PA. Muscle fiber composition was unaffected by OSA or CPAP. Increases in IMCL and EMCL are detectable at approximately 7 am in OSA patients and are partly attributable to overnight FFA excesses and high ScFAT or body mass index. CPAP decreases FFAs and IMCL by trend but significantly reduces EMCL.

Dietary phosphatidylcholine affects growth performance, antioxidant capacity and lipid metabolism of Chinese mitten crab (Eriocheir sinensis)

This study determined the effects of dietary phosphatidylcholine (PC) levels on growth performance, antioxidant capacity and lipid metabolism of juvenile Eriocheir sinensis. Six isolipidic and isonitrogenous diets were formulated with six graded levels of PC (0%, 1.36%, 2.76%, 4.34%, 5.74% and 7.10%) and fed to juvenile E. sinensis (0.52 ± 0.01 g) for eight weeks. The crabs in the PC-added groups had a better feed conversion ratio and higher final body weight, weight gain and specific growth rate than those in the PC-devoid group. The dietary PC supplement increased antioxidant capacity and reduced lipid peroxidation in the hepatopancreas of E. sinensis. The crabs fed the diet with PC addition showed lower whole-body total lipid contents than those fed the diet without PC addition. The diets supplemented with moderate PC promoted whole-body protein deposition. The total lipid content of the hepatopancreas was also markedly decreased in the PC-added groups, while the total lipid content in muscle showed an opposite trend in the hepatopancreas. In addition, the appropriate dietary PC facilitated the deposition of long-chain polyunsaturated fatty acids (especially C20:5n-3 and C22:6n-3) in muscle and hepatopancreas. The quantitative real-time PCR exhibited that the dietary PC reduced lipid deposition in the hepatopancreas of E. sinensis possibly through inhibiting lipid synthesis as well as facilitating lipid oxidation and transport. Based on the weight gain and specific growth rate, the broken-line regression analysis suggested that the optimum PC requirement of juvenile E. sinensis should be in the range of 2.89% - 2.95% of the diet by weight.

Rapid Phenotypic Stock Identification of Chinook Salmon in Recreational Fishery Management

AbstractRapid phenotypic stock identification in mixed‐stock fisheries can provide a useful alternative to more time‐intensive methods (e.g., coded wire tags, genetics) in assessing harvest and informing management decisions. We leveraged local ecological knowledge, existing stock identification methods, and understanding of life history differences to develop rapid stock identification tools for fall‐run Chinook Salmon Oncorhynchus tshawytscha encountered in the Buoy 10 recreational fishery at the mouth of the Columbia River. Specifically, we sought to differentiate between the fishery’s two dominant genetic lineages: lower river tules and upriver brights. We sampled recreationally landed Chinook Salmon in 2017, 2018, and 2019, assigned sampled individuals to functional reporting groups using a single‐nucleotide‐polymorphism‐based genetic baseline, and collected measurements on phenotypic traits. Using traits including pigmentation patterns (e.g., spotting), fin morphology, characteristics indicative of sexual maturity, and muscle lipid content, random forest classification models provided consistently high classification success across and within genetic groups (i.e., up to 90%). Classification success remained consistent over time within fishery seasons and between years but showed meaningful bias between sexes. Based on observed classification success, we developed and evaluated a categorical visual identification guide capable of facilitating more rapid trait observations and on‐site stock identification. The resulting classification key, built using classification trees and visual guide observations from 2019, achieved slightly lower classification success across and within genetic groups and had variable success among samplers. Compared with the existing use of coded wire tags in harvest assessment, phenotypic stock identification methods can provide more rapid and more numerous assignments, albeit with a greater degree of individual assignment error. Applied as a complement to standard methods like coded wire tags, the use of rapid phenotypic stock identification methods offers the potential for increased overall precision and timeliness in harvest assessments.

A comparative evaluation of the nutritional quality of three wild populations of female mitten crabs (Eriocheir sensu stricto) in northern China

Abstract There are three major wild populations of mitten crab (Eriocheir sensu stricto), Suifenhe River (SF), Tumenjiang River (TM) and Liaohe River (LH) in northern China. However, the information on the nutritional quality of these three populations of crabs is still scarce. Thus, we investigated and compared the tissue indices, total edible yield, proximate composition, fatty acid compositions and amino acid contents of these wild crab populations. We showed that: (1) TM population had the highest meat yield among the three populations; (2) TM recorded the highest moisture and the lowest total lipid content in ovary and muscle; (3) a higher level of total n-3 poly-unsaturated fatty acids was found in TM, except for the ovary in SF; (4) the three populations had similar essential amino acids scores. In conclusion, Eriocheir s.s. from these three populations all showed a high nutritional quality suitable for humans, especially the TM, which contains more eicosapentaenoic acid and docosahexaenoic acid.

Nano‑selenium supplements in high-fat diets relieve hepatopancreas injury and improve survival of grass carp Ctenopharyngodon Idella by reducing lipid deposition

To investigate the effects of supplementing nano‑selenium (Se) in high-fat diet (HFD) on hepatopancreas health and survival of grass carp, six types of experimental diets including low-fat diet (LFD), HFD and HFD supplemented with four levels (0.3 mg kg−1, 0.6 mg kg−1, 0.9 mg kg−1 and 1.2 mg kg−1) of nano-Se were used. After 10 weeks of feeding, growth, survival rate (SR), serum biochemical parameters, lipid contents of hepatopancreas and muscle, hepatopancreas and intraperitoneal fat histology, expression of genes related to lipid metabolism and AMPK activity in grass carp were determined. Results showed that the concentration of ALT and AST (indices for hepatopancreas injury) in serum significantly increased in grass carp fed with HFD, and the SR of grass carp fed with HFD significantly decreased compared to those fed with LFD, indicating the harmful effects of the HFD on grass carp. However, addition of 0.3 mg kg−1-1.2 mg kg−1 and 0.6 mg kg−1-1.2 mg kg−1 of nano-Se significantly reduced the levels of AST and ALT in grass carp compared to the HFD only group, respectively. As such, the improved SR was found in the grass carp fed with HFD supplied with nano-Se. Further, addition of 0.3 mg kg−1-1.2 mg kg−1 nano-Se in the diet significantly decreased the levels of serum triglyceride and total cholesterol, but improved the high-density lipoprotein cholesterol contents of grass carp, compared with the HFD group. The dietary nano-Se also increased the expression of genes related to fatty acid oxidation and triglyceride hydrolyses, such as PPARα, CPT1, ATGL, and LPL in the hepatopancreas which were suppressed by the HFD. A similar trend was observed in the muscle and intraperitoneal fat. Consequently, the decrease in the lipid contents and size of lipid drops in the hepatopancreas, the hepatosomatic index and the intraperitoneal fat index were observed in the grass carp fed with diets containing nano-Se. The alleviated hepatopancreas injury and improved SR of grass carp may be owing to the reduced lipid deposition by the dietary nano-Se. In addition, supplementation of 0.6 mg kg−1-0.9 mg kg−1 nano-Se in diets significantly enhanced the AMPK (key regulatory molecules of lipid metabolism) activity, which was inhibited by the HFD. In conclusion, supplementing 0.3 mg kg−1-0.6 mg kg−1 of nano-Se in diets relieved hepatopancreas injury and improved survival of grass carp by reducing lipid deposition. This could be due to the regulation of the expression of the genes related to lipid metabolism via the AMPK pathway.

Sex-specific lipid profiles in the muscle of Atlantic salmon juveniles

Energy allocation in juvenile fish can have important implications for future life-history progression. Inherited and environmental factors determine when and where individuals allocate energy, and timely and sufficient energy reserves are crucial for reaching key life stages involved in the timing of maturation and sea migration. In Atlantic salmon, lipid reserves are predominantly found in the viscera and myosepta in the muscle and have been shown to play a key role in determining the timing of maturity. This life-history trait is tightly linked to fitness in many species and can be different between males and females, however, the details of relative energy allocation in juveniles of different sexes is not well understood. Therefore, the aim of this study was to investigate the effects of sex, genetics and environment during juvenile development of salmon on the amount and composition of their lipid reserves. To do so, juvenile salmon were fed one of two different lipid food contents during their first summer and autumn under common-garden conditions. Muscle lipid composition and concentrations were determined by thin layer chromatography. The muscle lipid class concentrations covaried negatively with body length and males showed higher concentrations than females for phosphatidylcholine, cholesterol, sphingomyelin, and triacylglycerol. This sex-specific difference in major lipid classes presents a new scope for understanding the regulation of lipids during juvenile development and gives direction for understanding how lipids may interact and influence major life-history traits in Atlantic salmon.

Systemic oxidative stress is associated with lower aerobic capacity and impaired skeletal muscle energy metabolism in heart failure patients

Oxidative stress plays a role in the progression of chronic heart failure (CHF). We investigated whether systemic oxidative stress is linked to exercise intolerance and skeletal muscle abnormalities in patients with CHF. We recruited 30 males: 17 CHF patients, 13 healthy controls. All participants underwent blood testing, cardiopulmonary exercise testing, and magnetic resonance spectroscopy (MRS). The serum thiobarbituric acid reactive substances (TBARS; lipid peroxides) were significantly higher (5.1 ± 1.1 vs. 3.4 ± 0.7 μmol/L, p < 0.01) and the serum activities of superoxide dismutase (SOD), an antioxidant, were significantly lower (9.2 ± 7.1 vs. 29.4 ± 9.7 units/L, p < 0.01) in the CHF cohort versus the controls. The oxygen uptake (VO2) at both peak exercise and anaerobic threshold was significantly depressed in the CHF patients; the parameters of aerobic capacity were inversely correlated with serum TBARS and positively correlated with serum SOD activity. The phosphocreatine loss during plantar-flexion exercise and intramyocellular lipid content in the participants' leg muscle measured by 31phosphorus- and 1proton-MRS, respectively, were significantly elevated in the CHF patients, indicating abnormal intramuscular energy metabolism. Notably, the skeletal muscle abnormalities were related to the enhanced systemic oxidative stress. Our analyses revealed that systemic oxidative stress is related to lowered whole-body aerobic capacity and skeletal muscle dysfunction in CHF patients.

Reduced fatty acid β-oxidation improves glucose catabolism and liver health in Nile tilapia (Oreochromis niloticus) juveniles fed a high-starch diet

Fish are poor users of dietary carbohydrates and often display prolonged hyperglycemia and fat deposition after feeding high digestible carbohydrate diets. Recently, fatty acid β-oxidation (FAO) inhibition has been reported to increase glucose oxidation in fish. Therefore, this study tested the assumption that the inhibition of FAO with mildronate (MD, a carnitine synthesis inhibitor) might also increase glucose utilization and alleviate adverse effects induced by high starch diet (HSD) in Nile tilapia, Oreochromis niloticus. Nile tilapia juveniles (6.13 ± 0.11 g) were cultured in nine 200-L tanks (30 fish per tank) and divided into three groups (three tanks per group). The fish were fed twice a day (9:00 and 18:30) at 4% body weight by using a normal starch diet (NSD, 30% corn starch), a HSD (45% corn starch), or a HSD supplemented with MD (25 g/kg of diet, HSD + MD) for eight weeks. These three feeds contained approximately 35.8% protein and 6.4% lipid. The fish each tank were weighed every two weeks, and the feeding amount was adjusted accordingly. After the feeding trial, the fish fed on HSD showed higher hepatosomatic index (HSI), visceral somatic index (VSI), serum triglyceride concentration and whole-body and tissue (liver and muscle) lipid contents than those fed on NSD. The fish fed on HSD also had higher relative area of vacuolation in the liver, hepatic malondialdehyde (MDA) content, and aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities in the serum than those fed on NSD. Moreover, the fish fed on HSD increased serum glucose and insulin concentrations, and hepatic lactate, pyruvate and glycogen contents, but reduced whole-body protein content and dietary protein utilization than those fed on NSD, indicating that HSD induced fat deposition, liver damage, glucose intolerance and lowered protein-sparing effect. However, the fish fed on HSD + MD decreased hepatic carnitine content and FAO activity, attenuated the indexes related to fat deposition and liver damage, improved blood glucose clearance and whole-body protein deposition than those fed on HSD, suggesting that the adverse effects caused by HSD were reversed after FAO inhibition. Furthermore, the fish fed on HSD down-regulated the expression of genes associated with glucose uptake, glycolysis, FAO process, and lipolysis compared to those fed on HSD + MD and NSD, yet up-regulated lipogenic and proteolytic genes. These data suggested that inhibition of FAO improved glucose utilization and alleviated the HSD-induced adverse effects in Nile tilapia. This work demonstrates that, modifying mitochondrial FAO activity regulates the ability of fish to adapt to HSD intake through remodeling energy homeostasis. Our study provides new insights into improving carbohydrate utilization in aquatic animals.

Histological Evidence of Multiple Spawning in Wild Female Japanese Eel Anguilla japonica.

The post ovulatory follicle (POF) is an important and reliable tissue structure used to investigate the spawning history in teleost fish. Fresh POFs shortly after spawning are comprised of cellular (follicular cells) and acellular (basement membrane and fibrils such as elastic fibers) components. The cellular components are quickly disintegrated by means of apoptosis, while the acellular components persist for a longer period. Since cellular components are well visualized by conventional hematoxylin-eosin (HE) staining but acellular components are not stained well, old POFs that have lost cellular components are difficult to identify. In this study, periodic acid-Schiff and Victoria blue staining, which can distinctly visualize acellular POF components, were applied to the ovarian tissues of Japanese eel (Anguilla japonica) (n = 9) captured from June to August of 2008, 2009, and 2013 at the southern West Mariana Ridge, a spawning area for Japanese eels. Only new POFs were observed in seven females caught in June, and these females had ovaries with early-to mid-vitellogenic stage oocytes. Both fresh and old POFs were observed in a female caught in July, and only mid-vitellogenic stage oocytes were observed. Only old POFs and no vitellogenic stage oocyte were observed in a female caught in August. A progressive decrease in muscle lipid content, gonad somatic index, and condition factors was observed from June to August. Thus, the female Japanese eel can spawn at least twice or three times at most during spawning season, depending on energy reserve.

The interaction effects of dietary lipid, vitamin E and vitamin C on growth performance, feed utilization, muscle proximate composition and antioxidant enzyme activity of white leg shrimp ( Litopenaeus vannamei )

This study aimed at evaluating the interactive effects of dietary lipid, vitamin E and vitamin C on growth performance, feed efficiency, muscle composition and antioxidant enzyme activity of Litopenaeus vannamei for a period of 56 days. A total of 384 shrimp with an initial weight of 5.3 ± 1.1 g were stocked in 24 tanks. Eight experimental treatments were designed with two different levels of lipid (70 and 140 g kg−1), VitC (0.5 and 1.0 g kg−1) and VitE (0.1 and 0.3 g kg−1). The results showed that high levels of dietary VitE and VitC improved the survival rate and the growth, feed and antioxidant indices in shrimp. The best shrimp growth performance was observed at 70 g kg−1 of lipid, 1.0 g kg−1 of VitC and 0.3 g kg−1 of VitE. Dietary lipid levels had a significant effect on muscle lipid, moisture and VitE contents. Furthermore, the interaction between dietary lipid, VitC and VitE had a significant effect on VitC and VitE contents of muscle. The lowest T-AOC, SOD, CAT and GPX activity was observed at 70, 1.0 and 0.3 g kg−1 of dietary lipid, VitC and VitE respectively. The results also showed that the interaction of dietary VitE and VitC had a significant effect on growth and antioxidant enzyme activity of shrimp and improved their growth indices by reducing dietary lipid levels. Dietary lipid level of 70 g kg−1, in interaction with 1.0 g kg−1 VitC and 0.3 g kg−1 VitE, resulted in better growth and antioxidant status in L. vannamei.