Sturgeon Muscle Research Articles

Polyculture of pikeperch (Sander lucioperca) and Russian sturgeon (Acipenser gueldenstaedtii) using an artificial common pellet – Implications on feed to fish nutrient transfers in recirculating aquaculture system (RAS)

The purpose of this research was to investigate the effects of monoculture and polyculture on the utilization of an artificial common pellet to produce nutritious products, specifically pikeperch and Russian sturgeon, in a recirculating aquaculture system (RAS) for 84 days. The experiment was conducted under controlled conditions, with specific parameters for: water temperature (21.8±0.4 °C), initial weight of the fish (pikeperch: 18.17±2.65 g; sturgeon: 18.23±3.62 g), volume of the containers (working volume of 272 litres) and feeding rate (1.5 %). Five experimental groups were tested in triplicates, including monoculture groups (pikeperch: 63.46±18.49 g; sturgeon: 93.52±50.40 g) and three polyculture combinations [P90: 90 % pikeperch (68.63±13.79 g) + 10 % sturgeon (86.10±33.38 g); P80: 80 % pikeperch (76.88±18.06 g) + 20 % sturgeon (103.53±44.60 g); P70: 70 % pikeperch (81.51±19.24 g) + 30 % Russian sturgeon (94.48±33.25 g)]. The results indicated that the addition of Russian sturgeon to pikeperch tanks could lead to efficient transfer of feed lipid to fish biomass through sturgeons, but not pikeperch. Polycultures showed better lipid absorption (P70 lipid-ADC 96.06±1.96 %) from the common pellet than monocultures (pikeperch: lipid-ADC 91.93±6.37 %; sturgeon: lipid-ADC 97.08±2.07 %). Fillet lipid content of pikeperch remained unaltered across RAS monocultures and polycultures but changed positively in Russian sturgeon in polyculture (P70 2.64±0.71 % > P0 1.75±0.75 %). In both species, polyculture fillets accumulated 5–7 % higher MUFA (oleic acid, C18:1n-9) than monoculture fillets. The major conclusions drawn from this research are that polyculture group P90 had both fish species flesh with highest muscle reserves of glycine and proline. In polyculture, critically indispensable muscle lysine reserves depleted in pikeperch, but Russian sturgeon muscle amino acid profile was stable. Given the global constraints on land availability, the study proposes RAS polyculture as a potentially productive and nutritious aquaculture system of the future. The research also suggests that resilient species for RAS polyculture need to be identified, proposing Russian sturgeon as a possible candidate.

Dietary resveratrol improves the flesh quality of Siberian sturgeon (Acipenser baerii) by enhancing myofiber growth, nutrient accumulation and antioxidant capacity

BackgroundIn aquaculture, sturgeons are generally maintained in the confined spaces, which not only hinders sturgeon movement, but also threatens their flesh quality that seriously concerned by aquaculture industry. As a typical antioxidant, resveratrol can improve the flesh quality of livestock and poultry. However, the mechanism of resveratrol’s effect on the muscle of Siberian sturgeon is still unclear.ResultsIn this study, the dietary resveratrol increased the myofiber diameter, the content of the amino acids, antioxidant capacity markers (CAT, LDH and SOD) levels and the expression levels of mTORC1 and MYH9 in muscle of Siberian sturgeon. Further transcriptome analysis displayed that ROS production-related pathways (“Oxidative phosphorylation” and “Chemical carcinogenes-reactive oxygen species”) were enriched in KEGG analysis, and the expression levels of genes related to the production of ROS (COX4, COX6A, ATPeF1A, etc.) in mitochondria were significantly down-regulated, while the expression levels of genes related to scavenging ROS (SOD1) were up-regulated.ConclusionsIn summary, this study reveals that resveratrol may promote the flesh quality of Siberian sturgeon probably by enhancing myofiber growth, nutritional value and the antioxidant capacity of muscle, which has certain reference significance for the development of a new type of feed for Siberian sturgeon.

Potential Assessment of Sturgeon Muscle Tissue as a Development Basis for Specialized Athletes Nutrition

Specialized food products use in the athlete diet developed considering the needs for nutrients is one of the most important factors in achieving high sports results and rapid recovery after physical activity. The study aims at possibility assessment of the muscle tissue use of sturgeon fish as a basis for the specialized food products development for athletes. Total chemical composition analysis of 13 sturgeon muscle tissue samples demonstrated that these fish species belong to the protein one with 15.73–19.38% protein content. According to the fat content, there are two groups to be identified: Sib×Sevr, BS×AO, bester Burtsevsky, bester vnirovsky, RO×L belong to fatty fish species (8.22–13.49% fat), and bester Aksai, K, K×A, St×K, AO – to medium-fat fish (4.70–7.92% fat). The study of the amino acid score of muscle tissue proteins has shown their high biological value. Only Burtsevsky bester and Siberian sturgeon differed in the presence of a limiting amino acid (valine), the rest of the samples studied had an amino acid score of more than 100%. The highest content of carnosine dipeptide is observed in hybrids between Siberian sturgeon and stellate sturgeon (385 mg/100 g), between Kaluga and Amur sturgeon (382.6 mg/100 g), as well as in bester vnirovsky (331.2 mg/100 g) and Amur sturgeon (308.8 mg/100 g). The fatty acid composition analysis of lipids showed the unsaturated fatty acids prevalence in it and a high total content of polyunsaturated eicosapentanoic and docosahexaenoic fatty acids (5.79–12.70%). A comprehensive assessment of the chemical composition coefficient and structural and mechanical characteristics of minced meat based on sturgeon muscle tissue revealed that this type of raw material is efficient in product manufacture for athletes.

Squalene Supplementation as a Novel to Increase PUFA Content in Fish Tissues.

Squalene is an antioxidant that plays an essential role in fat metabolism. The study aimed to assess the effect of squalene supplied in feed on the growth performance, health status, and fatty acid profiles of muscle and liver of Siberian sturgeon, rainbow trout, and Eurasian perch. The experimental feeds containing 0%, 0.5%, and 1.0% squalene were prepared for each fish species. Hematological and biochemical indices, liver histology, and fatty acid profiling of muscle and liver were analyzed. Squalene supplementation was safe for fish, and no negative influence on growth status was observed. However, changes in the values of hematological and biochemical indicators were found, including the level of triglycerides in the blood of rainbow trout, and cholesterol in the blood of Eurasian perch. The addition of squalene influences the nucleocytoplasmic index values in all fish offered feed containing 1% squalene. The retention of squalene in the liver and muscle of experimental Siberian sturgeon was observed in both 0.5% and 1.0% squalene levels of feed. The PUFA and docosahexaenoic acid increase was observed in all fish in groups with squalene addition. Dietary squalene increases the content of PUFAs in tissues of the examined species.

Peptide fraction from sturgeon muscle by pepsin hydrolysis exerts anti-inflammatory effects in LPS-stimulated RAW264.7 macrophages via MAPK and NF-κB pathways

Previous studies have suggested that polypeptides extracted from milk, soybean, fish, eggs, and meat possess potential anti-inflammatory effects. To date, few studies have reported the anti-inflammatory function of sturgeon peptides and their underlying mechanisms are unknown. The current study was therefore to determine the anti-inflammatory potential of sturgeon peptides with lipopolysaccharide (LPS)-induced RAW264.7 inflammatory model. Pepsin hydrolysate (PeH) was purified by ultrafiltration and Sephadex G-15 gel filtration chromatography. PeH significantly reduced the inflammatory mediator (NO) and inflammatory cytokines (IL-6、TNF-α and IL-1β) expression in a dose-dependent manner. Moreover, the purified sturgeon peptide (F2) possessed strong antioxidant potential and effectively inhibited DPPH and ABTS free radicals. F2 significantly suppressed the expression of MAPKs, IκBα, and NF-κB p65, indicating that F2 exerted anti-inflammatory influence by the inhibition of MAPK and NF-κB pathways.

Satellite cell division and fiber hypertrophy alternate with new fiber formation during indeterminate muscle growth in juvenile lake sturgeon (Acipenser fulvescens)

Age-dependent changes in muscle fiber size, myonuclear domain volume, fiber-end-terminal configuration, fiber and fish growth, and stem cell or satellite cell (SC) number and proliferation were investigated in developing lake sturgeon (Acipenser fulvescens Rafinesque, 1817) to characterize indeterminate muscle growth during early life. We hypothesized that up to 29 months post hatch (MPH), SC numbers and mitotic activity, the mitotic cycle duration of SCs, fiber morphology, and the volume of cytoplasmic domains around fiber nuclei would change during periods of fiber hypertrophy and hyperplasia. Single-fiber cultures were used in pulse-chase studies of SC division and the Pax7+ SC population. The number of SCs per fiber increased until 17 MPH, peaking as a proportion of fiber nuclei at 3 and 17 MPH. SC cycle time decreased in duration with age after peaks at 3 and 5 MPH. Domain volume was high at 1 and 29 MPH and low from 2 to 6 MPH. Fibers with uniformly tapered ends were most frequent at 4 MPH. Results suggest 3 and 6–17 MPH as intervals for both SC proliferation and fiber hypertrophy, and that fiber growth alternated with new fiber formation (termed fiber hyperplasia) from 4 to 5 MPH and from 17 to 29 MPH. These patterns of cellular dynamics in lake sturgeon muscle growth advance our understanding of indeterminate growth.

Sturgeon protein-derived peptides exert anti-inflammatory effects in LPS-stimulated RAW264.7 macrophages via the MAPK pathway

• KIWHHTF, VHYAGTVDY and HLDDALRGQE are novel anti-inflammatory peptides derived from sturgeon muscle. • Three novel peptides suppress the release of NO、IL-1β, and IL-6. • Three novel peptides increase the SOD activity in the LPS-induced RAW264.7 cells. • Three novel peptides can down-regulate the MAPK pathway. Previous studies have demonstrated that polypeptides extracted from fish protein possess potential anti-inflammatory effects, but few studies have reported the underlying anti-inflammatory mechanism of sturgeon peptides. Hence, the goal of this study was to explore the peptide sequences with potential anti-inflammatory activity derived from sturgeon muscle protein in the lipopolysaccharide (LPS)-induced RAW264.7 inflammatory model. Fourteen novel peptides were identified in major muscle proteins by mass spectrometry, and three synthetic peptides – KIWHHTF, VHYAGTVDY, and HLDDALRGQE - decreased the release of inflammatory mediators and inflammatory cytokines (NO, IL-6, and IL-1β), while increasing SOD activity significantly in the LPS-induced RAW264.7 inflammatory model. Western blotting analysis revealed that these peptides suppressed the phosphorylation levels of MAPKs, indicating that these peptides exerted anti-inflammatory effects by inhibiting the MAPK pathway. The novel peptides potentially have application prospects as functional food ingredients.

Sturgeon hydrolysates alleviate DSS-induced colon colitis in mice by modulating NF-κB, MAPK, and microbiota composition.

Sturgeon muscle byproduct collected after caviar production is usually not fully utilized, and sometimes may be discarded, thus causing a lot of waste. Yet dietary protein hydrolysates, which may be derived from sturgeon muscle, have been reported to have versatile beneficial biological activities. Studying the biological activities of sturgeon muscle-derived hydrolysates holds much promise for adding value to sturgeon. The current study aimed to study the therapeutic anti-inflammatory effects of sturgeon muscle-derived hydrolysates and the underlying mechanisms. The administration of sturgeon hydrolysates (SH) significantly decreased the severity of DSS-induced damage, evidenced by increased body weight, colon length, and decreased disease activity index (DAI) and histological scores. SH also inhibited myeloperoxidase (MPO) activity and reduced the serum levels of IL-6, IL-1β, and TNF-α. Western blotting results revealed that SH suppressed DSS-induced activation of the NF-κB and MAPK pathways in the colon. Furthermore, SH partially restored the alteration of the gut microbiota in colitic mice. SH increased the Bacteroidetes/Firmicutes ratio and the relative abundance of Ruminococcaceae, Porphyromonadaceae, and Bacteroidetes S24-7, while decreased the abundance of potentially harmful bacteria Erysipelotrichaceae and Enterococcaceae. These results suggest that SH inhibited DSS-induced colitis by regulating the NF-κB and MAPK pathways and modulating microbiota composition.

Sex-related gene expression profiles in various tissues of juvenile Russian sturgeon (Acipenser gueldenstaedtii)

The expression profiles of key genes associated with sex differentiation in vertebrates, namely, amh, ar, cyp19, dmrt1, erα, erβ, foxl2, sox9, star, and vtg, were analyzed in the gonads, liver, muscle, and brain of Russian sturgeon (Acipenser gueldenstaedtii). The aims of this study were to determine in which tissue the signal for sex differentiation primarily occurs, and which factors are most important for gonadal differentiation. The sturgeons included in the study (180 days post-hatching; n = 20) were at the beginning of gonadal differentiation; five females, seven males, and eight individuals with disturbed germinal tissue development were identified. All of the examined genes except for star had diverse sex-related expression profiles in the brain. By contrast, in the gonads, only foxl2 expression was sex-dependent. With the exception of star and cyp19, all of the other genes were expressed in the muscle and liver, but there were no significant differences between sexes. The expression profiles of the analyzed genes in the brain were atypical, indicating feminization. This finding was in agreement with the high occurrence of individuals sharing female and male germinal tissue characteristics. The data presented here suggest that the sturgeon brain is the primary organ that stimulates other organs and tissues to differentiate into male or female, and that dmrt1 and foxl2 play major roles in sex differentiation in this species.

Effects of dietary α-ketoglutarate supplementation on the growth performance, glutamine synthesis and amino acid concentrations of juvenile hybrid sturgeon Acipenser schrenckii ♀ × Acipenser baerii ♂ fed high levels of soy protein concentrate

The present study was conducted to determine the effects of dietary α-ketoglutarate (AKG) supplementation on the growth performance, glutamine synthesis and amino acid concentrations of juvenile hybrid sturgeon Acipenser schrenckii ♀×Acipenser baerii ♂ fed high levels of soy protein concentrate (SPC). The study consisted of four isoproteic and isolipidic diets (including 100g of fish meal (FM)/kg or 0FM) with or without 10g AKG/kg supplementation. The results showed that the SPC diet had no effect (P>0.05) on the weight gain rate (WGR), feed conversion ratio (FCR), protein efficiency ratio (PER), condition factor (CF) or viscerosomatic index (VSI) compared with the FM diet. The WGR and PER were increased (P<0.05) by the addition of AKG compared with the FM and SPC diets. However, the FCR was decreased (P<0.05) by the addition of AKG. The concentration of ammonia in serum was decreased (P<0.05) by the addition of AKG compared with the FM and SPC diets. The Gln and activity of GS in the intestine of sturgeon fed the SPC+A and FM+A diets were significantly higher (P<0.05) than in sturgeon fed the SPC and FM diets. The concentrations of methionine, leucine and lysine in the muscle of sturgeon fed the SPC diet were significantly lower (P<0.05) than those of muscles in sturgeon fed the FM diet. The concentration of arginine was increased (P<0.05) by the SPC diet or the addition of AKG. The concentrations of aspartate and glutamate were increased (P<0.05) by the addition of AKG compared with the FM and SPC diets. These findings indicate that the SPC diet had no negative effect on growth performance compared with the FM diet (100gFM/kg), and that dietary AKG supplementation improved the growth performance and glutamine synthesis of the juvenile hybrid sturgeon.

Feeding Rates Affect Expression of Heat‐Shock Protein 70 in Green Sturgeon Fry

AbstractTwo growth trials were conducted to determine the effect of feeding rate on the responses of a heat‐shock protein (hsp70) in the fry of Green Sturgeon Acipenser medirostris. Four tanks were randomly assigned to each feeding treatment: 2.5, 5.0, 7.5, 10.0, 12.5 and 15.0% of body weight/d in trial I and 2.0, 3.0, 4.0, 5.0, 6.0 and 7.0% of body weight/d for trial II. The fry were raised indoor at 18°C and fed a commercial salmonid soft‐moist diet. Densities were 50 fry/tank in trial I fed for 49 d posthatch (dph) and 30 fry/tank in trial II fed for 70 dph. At the end of 1 week of feeding, five fish from each tank were subjected to heat shock by increasing the water temperature from 18°C to 28°C at a rate of 4°C/h and then holding at 28°C thereafter for 4 h before tissue samples were collected. Heat shock induced significant changes in the levels of hsp70 in the liver and white muscle of fish in all feeding treatments. However, feeding rate treatments had no significant effect on the basal and heat‐shocked levels of hsp70 in the liver of these fish. The lowest feeding rate significantly depressed the induced level of hsp70 in the muscle of Green Sturgeon. A feeding rate of 10.0% of body weight/d is suggested for Green Sturgeon at 49 dph and 6.0% at 70 dph, based on their maximum responses of hsp70 in white muscle tissue. This study indicates that the response of hsp70 in the liver and muscle of Green Sturgeon is sensitive to heat‐shock stress. The effect of different feeding rates on the response of hsp70 is also tissue‐dependent. This variation should be considered when hsp70 is used as a biomarker to evaluate heat‐shock response.

Isolation and characterization of collagen from the muscle of Amur sturgeon (Acipenser schrenckii)

The collagen in Amur sturgeon muscle was isolated using sodium chloride (salt-solubilized collagen, SSC, 3.02%), followed by acetic acid (acid-solubilized collagen, ASC, 31.56%) and then pepsin (pepsin-solubilized collagen, PSC, 58.49%). The collagens appeared to be dense sheet-like film linked by random-coiled filaments under SEM. There was no obvious difference in denaturation temperature (about 33°C) assessed by CD, while the melting temperature of SSC (115.82°C) was significantly lower than ASC and PSC (120.23 and 118.80°C, respectively) determined by DSC. SDS-PAGE showed that the collagens were mainly type I with similar amino acid profiles. FTIR confirmed the triple helical structure of the collagens, and indicated more hydrogen bond in PSC and more intermolecular crosslinks in ASC. These results provide some basis for elucidating the function of collagen in the development of meat texture during postmortem aging and processing.

Determination of pesticide residues in fish tissues by modified QuEChERS method and dual-d-SPE clean-up coupled to gas chromatography-mass spectrometry.

The aim of this research was to modify the Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) method for the determination of organochlorine and organophosphate pesticides in fatty animal matrices such as fish muscle tissues of carp and sturgeon collected from Carp Valley, Lesser Poland. Pesticides extraction effectiveness was evaluated at 0.030 mg kg(-1) spiking level and efficiency of the dispersive-solid-phase extraction (d-SPE) clean-up step was evaluated by comparison testing two different d-SPE clean-up stages, first the addition of the d-SPE sorbent combination (PSA + SAX + NH2), and secondly the addition of C18 after extracts enrichment with the d-SPE sorbent combination (PSA + SAX + NH2), introducing a novel concept of clean-up named dual-d-SPE clean-up. Analysis of pesticide residues was performed by Gas Chromatography Quadrupole Mass Spectrometry (GC/Q-MS) working in selected-ion monitoring (SIM) mode. Linear relation was observed from 0 to 200 ng mL(-1) and determination coefficient R(2) > 0.997 in all instances for all target analytes. Better recoveries and cleanliness of extracts in both samples, carp and sturgeon tissues, were obtained after C18 addition during the dual-d-SPE clean-up step. Recoveries were in the range 70-120%, with relative standard deviation lower than 10% at 0.030 mg kg(-1) spiking level for most pesticides. LODs ranged 0.001-0.003 mg kg(-1), while LOQs ranged 0.004-0.009 mg kg(-1). The proposed method was successfully applied analyzing pesticide residues in real carp and sturgeon muscle samples; detectable pesticide residues were observed, but in all of the cases contamination level was lower than the default maximum residue levels (MRLs) set by the European Union (EU), Regulation (EC) N 396/2005.

Characteristic Changes of Protein Occurring in Brine Salting Sturgeon at Different Levels of NaCl

The effects of brine salting on sturgeon muscle proteins were studied during the processing of salting at different levels of NaCl . The aim was to observe conformational stability and possible degradation or denaturation of sturgeon protein by determining the biochemical characteristics of protein using Fourier-transform-infrared spectroscopy( FTIR), sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), fluorescence and other means. The salting process significantly decreased the actomyosin content, Ca2+-ATPase activity,total and reactive sulfhydryls (SHs) and increased surface hydrophobicity of actomyosin. The results showed that the processing of salting salting induced the degradation or denaturation of actomyosin. From SDS–PAGE, actin was affected by salt to a lesser extent by the process than myosin heavy chain (MHC). From the FTIR, the secondary structure of protein changed significantly ,especiallyα-helix, at different levels of NaCl .

Fatty acid composition in tissues of the farmed Siberian sturgeon (Acipenser baerii)

The fatty acid (FA) compositions of the diet and diverse tissues of the farmed Siberian sturgeon (Acipenser baerii) were analyzed in detail to assess their nutritional quality. Twelve male fish were sampled for muscle, fat, liver, brain, gill, kidney and gonad and the tissue FA measured by gas–liquid chromatography. The FA profile of the diet diverged from the FA signatures of the tissues, where the sturgeons accumulated particular highly-unsaturated FA (HUFA). They were probably derived from the diet but, as previous studies have shown that fish can also have desaturase enzymes, endogenous synthesis of these FA cannot be excluded. The sturgeon muscle tissue contained HUFA in proportions comparable to those of other fish species that are considered good sources of n-3 polyunsaturated FA. The indices of atherogenicity and thrombogenicity were also within the values considered to be health-promoting.

Extraction of Fish Oil from the Muscle of Sturgeon Using Supercritical Fluids

This study evaluated the extraction of oil from sturgeon (Acipenser baeri) muscle using supercritical fluids. Response surface methodology (RSM) was used to identify and quantify the variables, namely extraction pressure, extraction time and CO2 flow rate on the yield of oil. Statistical analysis indicated that for all three variables, the quadratic terms and interactions between the variables had significant effects on yield (p &lt; 0.05). Polynomial regression model predictions were in good agreement with the experimental results, with a coefficient of determination of 0.9936 for yield. Maximum yield from sturgeon muscle was 26.83% with a pressure of 315.8 bar, extraction time of 10.8 min and CO2 flow rate of 3.5 l/min, which closely matched the predicted value (26.70%). The characteristics of the fish oil extracted with the supercritical fluids were superior to those of oil obtained by other methods.

Dietary fat content and feed supply influence growth and body composition in juvenile beluga sturgeon (Huso huso)

This study is to evaluate the impacts of two levels of fat on the fish growth, feed intake, and compositions of muscle, liver, and viscera on the juvenile Huso huso. There were four treatments: two experimental diets (high-fat: 30% and low-fat: 15%) and two feeding levels (100 or 60% of satiation). The treatments were assigned to 16 tanks each with 15 fish, with four replicates for each treatment. Beluga sturgeon juveniles with an initial weight of 61.3 ± 4.4 g were reared for 3 months. Increasing fat content of the diets resulted in an increased final weight (621.8 vs. 467.5 g for high-fat and low-fat diets, respectively, at 100% feeding level; p 0.05). Total feed intake was increased by the use of high-fat diet (487.8 vs. 365.0 g for high-fat and low-fat diets, respectively, at 100% feeding level; p < 0.01). Results also showed no interactions between fat level of the diets and feeding level in final weight and FCR. Beluga sturgeon muscle and liver fed high-fat diets contained higher fat than those fed low-fat diets (186.5 and 329.6 vs. 144.1 and 261.9 g kg−1 for high-fat and low-fat diets, respectively, at 100% feeding level; p < 0.01), and feeding levels did not change protein content of the examined organs. In conclusion, beluga sturgeon shows an enhanced growth on high-fat diet, and feed intake does not reduce by the use of high-fat diets.

Histopathological alterations of juvenile green (Acipenser medirostris) and white sturgeon (Acipenser transmontanus) exposed to graded levels of dietary methylmercury

Triplicate groups of juvenile green and white sturgeon (average weight of 30±2g) were exposed to one of four concentrations of dietary methylmercury (MeHg; 0, 25, 50, and 100mg MeHg/kg diet) for 8 weeks to determine and compare the sensitivity of the two sturgeon species from a histopathological perspective. After 4- and 8-week exposure, histological changes were examined in the kidney, liver, gill, skeletal muscle, and heart muscle of both species using light microscopy. Marked abnormalities were observed in the kidney and liver of both sturgeon species after each exposure period; the abnormalities showed progressive histological alterations in severity with increasing doses and duration of exposure. Renal lesions included tubular epithelium degeneration and necrosis, renal corpuscular disintegration, and interstitial tissue degeneration. The changes observed in the livers of both sturgeon species were glycogen depletion and vacuolar degeneration. In the gill and skeletal and heart muscle of green and white sturgeon fed MeHg-added diets, mild histological changes were observed but did not show pronounced difference between the two species. Although the lowest observed effect concentration in both species was the 25mg MeHg/kg diet, the histological changes in the kidney and liver were more pronounced at all treatments groups of green sturgeon than those of white sturgeon. The current results on structural changes of kidney and liver (i.e., more severe glycogen depletion and tubular epithelium degeneration in green sturgeon) confirmed our previous results, in that green sturgeon exhibited a higher mortality, lower growth rate, and lower protein, lipid, and energy contents in their whole body than white sturgeon under the same MeHg exposures.

Effect of vacuum‐packaging on the changes of Russian sturgeon muscle lipids during frozen storage

AbstractThe changes in fatty acid composition, non‐polar (triglycerols) and polar lipids (phospholipids), total free fatty acids and total cholesterol of Russian sturgeon (Acipenser gueldenstaedtii) were studied during 360 days of storage at −18°C. It was established that total neutral lipids and phospholipids content decreased and total free fatty acids concentration increased significantly during the frozen storage. Lower non‐polar and polar lipids content and higher free fatty acids concentration of vacuum‐packaged samples in comparison with air‐packaged samples were found. The changes in total cholesterol concentration and phospholipid classes of frozen stored sturgeon were not influenced by the frozen storage period and the type of packaging. It was established that the sturgeon polar lipids consisted mainly of phosphatidylcholine – 54.98 ± 0.85%, phosphatidylethanolamine – 28.42 ± 0.61%, and phosphatidylserine – 8.64 ± 0.45%. The increase of the total free fatty acids concentration was associated with the free n − 3 PUFA accumulation as a result of hydrolysis of non‐polar and polar lipids. During the frozen storage DHA percentage of non‐polar lipids and phospholipids decreased approximately 3 and 1.75%, respectively. After 360 days of storage at −18°C the n − 3/n − 6 PUFA ratio of total lipids decreased 4.9%.

Metabolic organization of the sturgeon Acipenser naccarii: A comparative study with rainbow trout Oncorhynchus mykiss

In order to assess the metabolic organization of Acipenser naccarii, a representative species of the ancient ancipenserid chondrosteans, the activity of key enzymes of the main metabolic pathways in the liver, white muscle, and heart, as well as the levels of plasma and tissue metabolites of this sturgeon species have been evaluated and compared to those of the advanced teleost Oncorhynchus mykiss. In general, the epibenthic character of A. naccarii is reflected in the lower specific activity of most enzymes evaluated, in comparison to those of the more active O. mykiss. However, the metabolic organization of this sturgeon species shows some particularities that clearly differed from that of teleosts. Whereas the liver is the main gluconeogenic organ in rainbow trout, both the liver and white muscle of sturgeon possess the same capacity for glucose synthesis, with glycerol being the more suitable glucose precursor. Unlike teleosts, the liver is the main site for lipid storage in sturgeon which would be related to its lower capacity to transport metabolites involved in lipid metabolism. Although the capacity to transport free fatty acids (FFA) is lower in sturgeon than in trout, HOAD activity shows that this acipenserid is able to oxidize fatty acids in extrahepatic tissues such as the heart. Also, both sturgeon and trout showed the same hepatic capacity to oxidize fatty acids. The liver of sturgeon possesses a higher capacity to synthesize ketone bodies than trout which would be a primitive trait to export these compounds as fuels for peripheral tissues in order to offset the low ability to transport FFA in the blood.