Siberian Sturgeon Research Articles

Comparative proteomic analysis of the ovarian fluid and eggs of Siberian sturgeon

BackgroundSturgeon species are living fossils that exhibit unique reproductive characteristics, and elucidation of the molecular processes governing the formation and quality of sturgeon eggs is crucial. However, comprehensive data on the protein composition of sturgeon ovarian fluid (OF) and eggs and their functional significance are lacking. To address this knowledge gap, the aim of the present study was to conduct a comprehensive comparative proteomic analysis of Siberian sturgeon OF and eggs using liquid chromatography–mass spectrometry (LC–MS/MS).ResultsA total of 617 proteins were identified in OF, and 565 proteins were identified in eggs. A total of 772 proteins showed differential abundance. Among the differentially abundant proteins, 365 were more abundant in OFs, while 407 were more abundant in eggs. We identified 339 proteins unique to OFs and 287 proteins specific to eggs, and further investigated the top 10 most abundant proteins in each. The functional annotation of the OF proteins highlighted their predominant association with immune system processes, including the complement and coagulation cascade, neutrophil and leukocyte-mediated immunity, cholesterol metabolism, and regulation of the actin cytoskeleton. Analysis of egg proteins revealed enrichment in metabolic pathways, such as oxidative phosphorylation and fatty acid metabolism, and protein ubiquitination and translation. OF-specific proteins included extracellular matrix and secretory vesicles, and eggs were enriched in proteins localized to mitochondria and ribosome components.ConclusionsThis study presents the first comprehensive characterization of the protein composition of sturgeon OF and eggs and elucidates their distinct functional roles. These findings advance our understanding of sturgeon reproduction, OF-egg signaling and the origin of OF proteins. The mass spectrometry proteomics data have been deposited in the ProteomeXchange Consortium with the dataset identifier PXD044168 to ensure accessibility for further research.

Dietary Protein Optimization for Growth and Immune Enhancement in Juvenile Hybrid Sturgeon (Acipenser baerii × A. schrenckii): Balancing Growth Performance, Serum Biochemistry, and Expression of Immune-Related Genes.

This study aimed to evaluate the effects of dietary protein levels on growth performance, serum indices, body amino acid composition, and intestinal gene expression in juvenile hybrid sturgeon (Acipenser baerii × A. schrenckii). Hybrid sturgeons (initial weight 29.21 ± 2.04 g) were fed isolipidic diets containing 30%, 33%, 36%, 39%, 42% or 45% crude protein for 12 weeks (n = 18 tanks, 30 fish/tank). Results showed significant differences between treatments, where weight gain and protein efficiency ratio peaked optimally between 35.9% and 38.3% dietary protein. Serum parameters such as glucose, alanine aminotransferase, aspartate aminotransferase, superoxide dismutase, and lipid peroxidation levels varied significantly with changes in dietary protein levels. Specifically, the highest enzymatic activities and growth parameters were observed in groups fed with 33% to 39% protein, enhancing whole-body concentrations of lysine, leucine, phenylalanine, proline, and glutamic acid. Immune parameters such as immunoglobulin M and lysozyme activity also showed peak levels at higher protein concentrations, particularly notable at 42% for lysozyme and 36% for both component 3 and immunoglobulin M. Gene expression related to immune and growth pathways, including MyD88, TLR1, IL-8, IL-6, NF-κB, and IL1β, was significantly upregulated at protein levels of 33% to 36%, with a noted peak in expression at 39% for TLR1, IL-10, and TOR signaling genes, before diminishing at higher protein levels. Overall, the dietary protein requirement for juvenile hybrid sturgeon ranges from 35.9% to 38.3% crude protein.

Tissue-specific Biomarker Metabolites of Meat, Fat and Egg of Siberian Sturgeon

Tissue-specific Biomarker Metabolites of Meat, Fat and Egg of Siberian Sturgeon

Immunomodulatory effect of potassium diformate and sodium diformate on humoral immunity and antioxidant capacity in Acipenser baerii: Cytokine and high-mobility group protein gene induction

The research examined the impact of adding potassium diformate (KDF) and sodium diformate (NDF) to the diet of Siberian sturgeon (Acipenser baerii) and how it influenced their antioxidant levels and immune responses. The fish (n = 315; 17.85 ± 0.2 g initial weight) were fed with seven diets for 56 days, including a control group (unsupplemented diet) and groups with varying levels of KDF (0.15, 0.3, and 0.5%) and NDF (0.15, 0.3, and 0.5%). After the feeding trial, the groups that consumed KDF or NDF demonstrated a dose-responsive elevation in serum superoxide dismutase, catalase, and glutathione peroxidase levels, along with an overall increase in total antioxidant capacity compared to the control group (P < 0.05). These groups also had lower malondialdehyde levels (P < 0.05) and improved immune functions, including higher levels of immunoglobulin M, total protein, albumin, globulin, the activities of lysozyme, respiratory burst, and alternative complement (P < 0.05). Also, the serum bactericidal activity experienced a significant increase (maximum in 0.5% NDF treatment) in the groups subjected to experimental feeding compared to the control group (P < 0.05). The transcription levels of interleukin-1 beta (IL-1β), interleukin 8 (IL-8), tumor necrosis factor-alpha (TNF-α), high mobility group box 1 (AbHMGB1), and high mobility group box 2 (AbHMGB2) genes in the head kidney were significantly upregulated in fish fed with different doses of KDF or NDF compared to the control group (P < 0.05). The most significant upregulation was observed in the group that received 0.5% NDF. Moreover, the experimental groups demonstrated a lower cumulative mortality rate of the fish following exposure to Aeromonas hydrophila AB005 infection compared to the control group (P < 0.05), with the lowest mortality rate observed in the 0.5% NDF or KDF group. Overall, the results suggest that dietary KDF or NDF, especially 0.5% NDF, are promising as environmentally friendly options and sustainable immunostimulants in Siberian sturgeon aquaculture.

Влияние смещения половых циклов на репродуктивные характеристики самок сибирского осетра и рыбоводно-биологические характеристики молоди

Modern industrial fish farms have specialised fish-breeding equipment that allows them to artificially regulate fish rearing, such as getting spawners into a pre-spawning stage at the time required by fish farmers. In this context, there has been some interest in determining the effect of rearing conditions and husbandry of Siberian sturgeon spawners on the progeny. Various abiotic and biotic environmental factors were modelled using the test sites of the Branch for Freshwater Fisheries of the Russian Federal Research Institute of Fisheries and Oceanography (RFRIFO). Female Siberian sturgeons of the sixth domestication generation of 2008 were used in the experiments. Weight gain has a positive effect on relative and individual fecundity in females. Relative fecundity decreases after resorption. Female eggs get larger with age, however the difference in body weight of juveniles produced from smaller eggs after growing is only 13%. Throughout the rearing period, the condition factor in juveniles ranges from 0.088 to 0.094, representing 46.3-49.4% of the maximum value. When comparing the rearing conditions in all groups of females, no correlation was found between the duration of interspawning interval (285 or 600 days) and the thermal constant during this period (4.970-5.124 and 10.095 degree days) and relative fecundity. According to the studies, a shift in the timing of gametogenesis caused by a force majeure has no effect on reproductive product quality and the ensuing progeny.

Preliminary rearing outcomes of Siberian sturgeon, Acipenser baerii Brandt, juveniles in autonomous hatching and rearing modules

Abstract This study analyzed the rearing indicators of Siberian sturgeon (Acipenser baerii) juveniles reared in tanks of different shapes and at various stocking densities. Rearing was conducted in autonomous hatching and rearing modules. Fish of an average body weight of 47.3±1.0 g were divided into four experimental groups: CL, RL, CH, and RH, which differed in stocking density (20 specimens and 50 specimens) and tank shape (C – circular, R – rectangular). The experiment ran for 28 days. Two-factor analysis indicated that lower stocking density significantly affected the final body weight of juvenile Siberian sturgeon, while tank shape had no effect on growth. The results of the current study on rearing Siberian sturgeon juveniles indicated that tanks of different shapes can be applied, but faster growth was obtained at a lower stocking density.

The effect of bisphenol A on antioxidant defense and the structure and function of the liver of Siberian sturgeon (Acipenser baerii).

The present study was conducted to investigate the biochemical and histological changes of liver tissue in Siberian sturgeon (Acipenser baerii) exposed to different doses of bisphenol A (BPA). One hundred and eighty pieces of 1-year-old A. baerii with an average weight of 200-250 g bought and randomly distributed in 18 tanks (n = 10). After 2 weeks of adaptation, the fish received intraperitoneal injections of 1, 10, and 100 μg/g/week BPA and μg/g/week of 17β-estradiol intraperitoneally. The solvent control group received only peanut oil, while the control group did not receive any injections. In order to investigate histological changes of the liver, after 2 weeks the liver samples were taken, fixed in 10% formalin solution and slides prepared by routine histological methods. For assaying antioxidant defense status, the liver tissue from three fish of each replicates was captured and after homogenization, activity of catalase, superoxide dismutase, and glutathione peroxidase and malondialdehyde measured. The most important histological changes observed in the liver tissue were: vacuolation of hepatocytes, nuclear hypertrophy, necrosis of liver cells, expansion of sinusoids, and accumulation of fat cells. In the highest dose, the intensity of tissue changes increased. Activity of antioxidant enzymes and malondialdehyde content increased in fish exposed to 100 μg/g/week BPA in compare with other groups (p < .05). According to our findings, it could be concluded that liver histology was affected by BPA and tissue damage had occurred, which had led to changes in blood parameters. Also, the obtained results showed that the high concentrations of BPA used in this study stimulate the antioxidant defense. RESEARCH HIGHLIGHTS: BPA evoke oxidative stress in Siberian sturgeons in high dose of exposure. Severity of liver histologic lesions was dose dependent.

Neglected function of gastrin to reduce feeding in Siberian sturgeon (Acipenser baerii) via cholecystokinin receptor B.

Gastrin is an important intragastrointestinal hormone, but reports on its regulation of feeding behavior in fish are still scarce. This study aimed to determine the feeding regulatory function of gastrin in sturgeon. In this study, a gastrin/cholecystokinin-like peptide was identified in the genomes of sturgeon and proved to be gastrin by evolutionary tree analysis. Tissue distribution of gastrin and its receptor, cholecystokinin receptor B (CCKRB), showed that both had high mRNA abundance in the hypothalamus and gastrointestinal tract. In the duodenum, gastrin and CCKRB mRNAs were reduced at 1h of fasting, and both were also observed in the stomach and hypothalamus in response to changes in feeding status. Sulfated gastrin 17 is the major form of gastrin in vivo. Therefore, we investigated the effect of sulfated gastrin 17 on feeding by intraperitoneal injection into Siberian sturgeon using sulfated gastrin 17. The results showed that gastrin 17 significantly reduced the cumulative feeding of Siberian sturgeon in the short term (1, 3 and 6h) and long term (1, 2, 3, 4, 5 and 7days). Finally, we explored the potential mechanism of feeding inhibition after intraperitoneal injection of gastrin 17 for 7 consecutive days. The results showed that gastrin 17 treatment significantly increased the mRNA levels of anorexigenic peptides (cart, cck and pyy), while it had no significant effect on the mRNA abundance of orexigenic peptides (npy and agrp). In addition, gastrin 17 treatment significantly affected the expression of appetite signaling pathways in the hypothalamus, such that the mRNA expression of ampkα1 was significantly reduced, whereas the mRNA abundance of stat3, mtor and s6k was significantly increased. In conclusion, the present study confirmed the anorectic effect of gastrin on Siberian sturgeon.

Distribution of gamma-aminobutyric acid immunoreactivity in the brain of the Siberian sturgeon (Acipenser baeri): Comparison with other fishes.

Gamma-aminobutyric acid (GABA) is the main inhibitory neurotransmitter in the central nervous system (CNS) of vertebrates. Immunohistochemical techniques with specific antibodies against GABA or against its synthesizing enzyme, glutamic acid decarboxylase (GAD) allowed characterizing GABAergic neurons and fibers in the CNS. However, studies on the CNS distribution of GABAergic neurons and fibers of bony fishes are scant and were done in teleost species. With the aim of understanding the early evolution of this system in bony vertebrates, we analyzed the distribution of GABA-immunoreactive (-ir) and GAD-ir neurons and fibers in the CNS of a basal ray-finned fish, the Siberian sturgeon (Chondrostei, Acipenseriformes), using immunohistochemical techniques. Our results revealed the presence and distribution of GABA/GAD-ir cells in different regions of the CNS such as olfactory bulbs, pallium and subpallium, hypothalamus, thalamus, pretectum, optic tectum, tegmentum, cerebellum, central grey, octavolateralis area, vagal lobe, rhombencephalic reticular areas, and the spinal cord. Abundant GABAergic innervation was observed in most brain regions, and GABAergic fibers were very abundant in the hypothalamic floor along the hypothalamo-hypophyseal tract and neurohypophysis. In addition, GABA-ir cerebrospinal fluid-contacting cells were observed in the alar and basal hypothalamus, saccus vasculosus, and spinal cord central canal. The distribution of GABAergic systems in the sturgeon brain shows numerous similarities to that observed in lampreys, but also to those of teleosts and tetrapods.

Evaluation of the effectiveness of the use of a complex of antibacterial drugs for the treatment of bacterial hemorrhagic septicemia in fish

The aim of the study was to develop therapeutic measures to combat bacterial hemorrhagic septicemia of fish using a complex of antibacterial drugs “Levofloxacin” and “Chlortetracycline”.Methods used: experiments were carried out in aquarium conditions on juvenile carp and hybrids «Siberian sturgeon×Kaluga» (hereinafter hybrid SO×K) infected with a mixed culture of pathogens: highly pathogenic strains of Aeromonas sp., strains of R.R. Acinetobacter and Citrobacter. In the experiment, 2 variants of the use of antibiotics for a course of 7 days were tested. Bacteriological seeding of fish parenchymal organ samples was carried out on nutrient and differential diagnostic media.Novelty: it consists in working out the scheme of application for fish of a complex of new antibiotics for aquaculture.Results: the results of the evaluation of the therapeutic effect of antibiotics “Levofloxacin” + “Chlortetracycline” in the treatment of bacterial hemorrhagic septicemia are presented. The cessation of fish death was noted the next day after the start of therapy. Positive results were obtained in carp — with a combination of levofloxacin at a dosage of 1000 mg/kg of ichthyomass and chlortetracycline — 100 mg/kg of ichthyomass, in a hybrid of SO×K — 500 mg/kg of ichthyomass of levofloxacin + 200 mg/kg of ichthyomass of chlortetracycline. Evaluation of their combinations with different dosages did not show 100% effect. The difficulties of therapy have been identified, which are associated with the spread of strains of microorganisms resistant to antibacterial drugs.Practical significance: the developed method of therapy is effective, reduces the damage from the disease and can be recommended when developing measures to combat bacterial hemorrhagic septicemia in fish in aquaculture.

State of the Siberian sturgeon population in the Middle Lena in summer

The purpose: to obtain modern data on the distribution, abundance, size composition and biological state of the sturgeon in the middle reaches of the Lena River.Material: data of scientific accounting survey using bottom drift nets in summer 2022.The results: Siberien sturgeon is dstributed irregularly on a 400‑kilometer stretch of the river from the city of Yakutsk to the Vilyui River, with the highest average density near the Vilyui River mouth 163 ind./km2, while sturgeon densities in the areas of Yakutsk and the Aldan River mouth were 71 and 44 ind./km2 respectively. The highest density of fish with the smallest average size in the area near the Vilyui mouth indirectly indicates the presence of a separate herd in the Vilyui River. The average density of fish over the entire 400‑km area was 93 ind./km2. The sturgeon length to the end of the middle rays (ac) was from 21 to 86 cm; on average 43.4 ± 10.7 cm. The modal size class for the sturgeon in catches in 2022 was 41–50 cm (44% of the total catch). The fish weight ranged from 40 to 3800 g. The average weight of individuals was 0.557. More than 80% of fish from all catches weighed up to 700 g. The weight of fish with a length ac 62–71 cm ranged from 0,400 to 1.415 kg, on average 1.0 kg. There were only 2.5% of commercial individuals in the total harvest. Sexually mature females were noted only near the Aldan mouth, where their share was 11% that may indicate the presence of spawning grounds in its channel. In the sample of fish that underwent a complete biological analysis (one third of the catches), sexually mature males were not observed. Estimated number of sturgeon: in Yakutsk city area — 17000 ind., in the Aldan mouth area — 47000 ind., in the Vilyui mouth area — 55000 ind. The total number of Siberian sturgeon on a 400‑kilometer stretch of the Lena River was at least 120000 ind. The state and structure of sturgeon population corresponds to the average statistical retrospective data.Practical value: the results obtained will improve the efficiency of assessing the distribution and stock of sturgeon in the Lena River.

Identification of C1q/TNF-related protein 4 as a novel appetite-regulating peptide that reduces food intake in Siberian sturgeon (Acipenser baerii)

Emerging findings point to a role for C1q/TNF-related protein 4 (CTRP4) in feeding in mammals. However, it remains unknown whether CTRP4 regulates feeding in fish. This study aimed to determine the feeding regulation function of CTRP4 in Siberian sturgeon (Acipenser baerii). In this study, the Siberian sturgeon ctrp4 (Abctrp4) gene was cloned, and Abctrp4 mRNA was shown to be highly expressed in the hypothalamus. In the hypothalamus, Abctrp4 mRNA decreased during fasting and reversed after refeeding. Subsequently, we obtained the AbCTRP4 recombinant protein by prokaryotic expression and optimized the expression and purification conditions. Siberian sturgeon (81.28 ± 14.75 g) were injected intraperitoneally using 30, 100, and 300 ng/g Body weight (BW) AbCTRP4 to investigate its effect on feeding. The results showed that 30, 100, and 300 ng/g BW of the AbCTRP4 significantly reduced the cumulative food intake of Siberian sturgeon at 1, 3, and 6 h. Finally, to investigate the potential mechanism of CTRP4 feeding inhibition, 300 ng/g BW AbCTRP4 was injected intraperitoneally. The findings demonstrated that AbCTRP4 treatment for 1 h significantly promoted the mRNA levels of anorexigenic peptides (pomc, cart, and leptin) while suppressing the mRNA abundances of orexigenic peptides (npy and agrp).In addition, the jak2/stat3 pathway in the hypothalamus was significantly activated after 1 h of AbCTRP4 treatment. In conclusion., this study confirms the anorexigenic effect of CTRP4 in Siberian sturgeon.

Identification, characterization and the inflammatory regulating effect of NOD1/2 in sturgeon

As an ancient species with both conservation and commercial value, Sturgeon's inflammatory regulation mechanism is a research point. Nucleotide-binding and oligomerization domain-containing proteins 1 and 2 (NOD1/2) are classical intracellular pattern recognition receptors (PRRs) in immunity of anti-bacterial infection. However, the characterization and function of NOD1/2 in Sturgeon are still unclear. In this study, we analyzed the synteny relationship of NOD1/2 genes between Acipenser ruthenus and representative fishes at the genome-level. Results showed that the ArNOD2 collinear genes pair was present in all representative fishes. The duplicated ArNOD1/2 genes were under purifying selection during evolution as indicated by their Ka/Ks values. To explore the function of NOD1/2, we further investigated their expression patterns and the effects of pathogenic infection, PAMPs treatment, and siRNA interference in Acipenser baerii, the sibling species of A. ruthenus. Results showed that both AbNOD1/2 were expressed at early developmental stages and in different tissues. Pathogenic infection in vivo and PAMPs treatment in vitro demonstrated that AbNOD1/2 could respond to pathogen stimulation. siRNA interference with AbNOD1/2 inhibited expression levels of RIPK2 and inflammatory cytokines compared to the control group after iE-DAP or MDP treatment. This study hinted that the AbNOD1/2 could stimulate the inflammatory cytokines response during evolutionary processes.

Hsd17b1 is a key gene for ovarian differentiation of the Siberian sturgeon.

This is the first work using gonads from undifferentiated, genetically-sexed Siberian sturgeon describing expression changes in genes related to steroid synthesis and female and male sex differentiation. One factor identified as relevant for ovarian differentiation was the gene coding for the enzyme Hsd17b1, which converts estrone into estradiol-17β. hsd17b1 was highly activated in female gonads at 2.5 months of age, around the onset of sex differentiation, preceding activation of two other genes involved in estrogen production (cyp19a1 and foxl2). hsd17b1 was also strongly repressed in males. Two known foxl2 paralogs are found in Siberian sturgeon-foxl2 and foxl2l-but only foxl2 appeared to be associated with ovarian differentiation. With regard to the male pathway, neither 11-oxygenated androgens nor classic male genes (amh, dmrt1, sox9, and dhh) were found to be involved in male sex differentiation, leaving open the question of which genes participate in early male gonad development in this ancient fish. Taken together, these results indicate an estrogen-dependence of female sex differentiation and 11-oxygenated androgen-independence of male sex differentiation.

Use of ultrasonic screening in aquaculture for the directed formation sturgeon and salmon fish mature stocks

The results of research work for the period from 2018 to 2023 on the use of early non-invasive functional ultrasound screening for the purpose of targeted formation of highly productive mature-brood stocks of Siberian sturgeon of the Ob, Yenisei, Baikal, Lena populations, European sterlet of the Kama population, Siberian sterlet of the Ob, Yenisei, Irtysh populations on main full-cycle industrial fish-breeding farms of Eastern and Western Siberia using water recirculation systems are presented in the article. Biotechnological methods for the formation of highly productive mature stocks using ultrasound monitoring are described. The number of individuals with pathologies and anomalies in the development of the reproductive system, liver, gallbladder and other internal organs were estimated; treatment methods were proposed. For the first time studies on the use of ultrasound for visualizing the gonads, determining the stages of maturity, detecting diseases of the heart, liver, gallbladder in salmon fish (trout, Atlantic salmon) grown in aquaculture have been carried out. For the first time ultrasound and histological studies were carried out to study the nature of “ink spots” on the skin of Siberian sturgeon Lena population from natural habitat. It was found that in the skin of sturgeon during pathology there was a growth of epidermal cells. Melanin melanocytes increased in both epidermis and dermis. At the same time there were no elastic fibers of the epidermis after painted according to Van-Gison. All these changes may indicate melanoma.

Результати отримання ікри від вперше дозрілих плідників осетра (Acipenser baerii Brandt, 1869), вирощених в індустріальних умовах

Purpose. To determine and evaluate productive parameters in the process of artificially obtaining ovulated eggs in different seasons from brood Siberian sturgeon Acipenser baerii Brandt, 1869 at first maturity grown in conditions of floating cage systems with a natural water temperature of the forest-steppe of Ukraine. Methodology. The material for the study were 65 individuals of age-8+ to 10+ sturgeon females with a body weight of 6.02‒8.64 kg firstly used in breeding works, which were grown using intensive technology in floating cages installed in a water body with a natural temperature regime of the forest-steppe zone. Experiments on obtaining mature eggs were conducted in non-traditional breeding periods — in winter (February) and at the end of spring (the last decade of May). In the winter, a recirculation aquaculture system was used with the use of special methods of preparing brood fish in the process of obtaining mature eggs. Collection of ovulated eggs was carried out with the preservation of life of brood fish after hormonal stimulation of gonad maturation using a carp pituitary preparation. Determination of productive parameters and study of physicochemical factors of the environment were carried out according to generally accepted methods. Findings. In different seasons of the year at a water temperature of 14–21°C, high efficiency of gonad maturation was registered in both groups of brood fish. The average weight of mature eggs obtained in separate groups of sturgeon females was 1.02–1.15 kg with an average gonadosomatic index of 13.92–15.42%. 94–97% of fish responded to pituitary stimulation in different groups of brood fish. The duration of brood fish maturation after the second (decisive) injection with a total dose of a gonadotropic substance of 3.5–4.0 mg/kg of fish weight varied within 14–25 hours. The survival rate of brood fish after egg collection was close to 94%. Originality. The results of obtaining mature eggs from Siberian sturgeon (Acipenser baerii) females at first maturity using the industrial fish farming technology, which is not common for aquaculture in Ukraine, were determined and analyzed. Practical value. The study results are of interest for the development of modern sturgeon aquaculture technologies in the conditions of industrial-type farms, primarily for the organization of caviar production. Keywords: brood sturgeon (Acipenser baerii), industrial fish farming, oocyte ovulation, productive parameters, caviar production.

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.

The effects of diets containing rapeseed meal on Siberian sturgeon (Acipenser baerii) growth, muscle composition, and physiological performance

Sturgeon farming is a rapidly developing aquaculture sector which requires high-quality feeds. As an ingredient of animal feeds, fishmeal is often replaced with cheaper plant-based protein sources, such as rapeseed cake meal, a by-product of canola oil pressing. The aim of the present study is to evaluate the effects of diets containing various levels of rapeseed cake meal on the juvenile Siberian sturgeon (Acipenser baerii) growth, hematological and biochemical parameters, as well as muscle composition. An 8-week feeding trial was conducted on fish with average body weight of 216.2 ± 45.7 g. Fish were fed diets were 0%, 10%, 20%, and 30% of fish meal and soybean meal were replaced with rapeseed meal (groups A, B, C, and D, respectively). Additionally in E diet (30% rapeseed meal) effects of phytase addition RENOZYME® HiPhos 20000 in concentration 2000 IU was tested. During the experiment, no mortalities were observed in each of the studied groups. Similar values of morphometric and breeding parameters were observed in groups A, B, C, D and E. No hematological effects of rapeseed diets occurred, except for significantly lower erythroblast levels in groups B, C, D, and E compared to A. Group B showed a higher plasma glucose concentration compared to the other groups. ALT activity in groups D and E were lower than in groups A, B, and C. The muscles of individuals from group B showed the highest dry matter and fat content, while the highest protein content occurred in group C. Despite significant differences in the values of some parameters, the obtained results indicate that the replacement of 10–30% of fishmeal with rapeseed meal in the feed for the juvenile Siberian sturgeon did not compromise fish survivability, growth performance, health, or body composition, although phytase addition did not improve the effects of administering rapeseed-containing feed.

Dietary Mentha piperita essential oil loaded in chitosan nanoparticles mediated the growth performance and humoral immune responses in Siberian sturgeon (Acipenserbaerii)

Siberian sturgeon (Acipenser baerii) fry often face environmental stressors that can compromise their immune system, rendering them susceptible to opportunistic pathogens in intensive aquaculture systems. In this study, we explored the innovative use of chitosan nanoparticles loaded with Mentha piperita essential oil (MPO/CNPs) as a dietary supplement to improve the growth and immune responses of A. baerii. The results demonstrated that the addition of MPO/CNPs to the diet led to significant improvements in growth, as evidenced by increased red blood cell count, hematocrit, haemoglobin concentration, and reduced triglyceride levels. Furthermore, significant differences were observed in the immune parameters for the treatment groups receiving Mentha piperita essential oil loaded in chitosan nanoparticles (MPO/CNPs), including enhanced lysozyme activity, immunoglobulin M (IgM) levels, respiratory burst activity, and ACH50 activity. Additionally, gene expression analysis revealed upregulation of key immune-related genes in the MPO/CNPs-treated groups. These findings suggest that the use of MPO/CNPs can enhance the growth and bolster the immune defences of Siberian sturgeon fry, contributing to more sustainable production in intensive aquaculture environments.

Effects of Chronic Heat Stress on Kidney Damage, Apoptosis, Inflammation, and Heat Shock Proteins of Siberian Sturgeon (Acipenser baerii)

Chronic heat stress caused by global warming can have serious implications for fish survival. The kidney plays a central role in many homeostatic functions, including water and electrolyte regulation. However, there is limited knowledge about the effect of heat stress on fish kidneys. In this study, water temperatures were increased from 20 °C to 24 °C and 28 °C in 8 days at a warming rate of 1 °C/d, and then maintained for 12 days. We investigated the effects of mild heat stress (24 °C) and high heat stress (28 °C) on Siberian Sturgeon (Acipenser baerii) kidneys using histological observation, flow cytometry detection, and RT-qPCR. Our histological observations revealed that heat stress caused significant infiltration of inflammatory cells in the kidney, especially at 28 °C. The flow cytometry assay demonstrated a significant increase in the number of apoptotic cells after heat stress at 28 °C compared to a control group at 20 °C (p = 0.033). The level of plasma creatinine was significantly increased in the 28 °C group compared to the control group (p = 0.001). In addition, the mRNA expression levels of heat shock protein GRP75 increased (p = 0.009). The results indicate that heat stress at 28 °C caused damage to the kidneys of A. baerii and triggered the protective response of heat shock proteins. In conclusion, this study contributes to the understanding of the coping strategies of the kidney of A. baerii for chronic heat stress.