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The purpose of this work was to assess the degree of genotoxic influence of the habitat on individuals of Russian sturgeon and sterlet raised in cage farming conditions in the Volga delta, using micronucleus and DNA comet tests.The blood of the individual Russian sturgeon and sterlet was shaved off during their lifetime. A comet DNA test was performed using the alkaline method. The number of erythrocytes with micronuclei was determined microscopically. To assess the physiological state of sturgeons, conventional hematological and biochemical methods were used.In the samples of fish blood smears studied, the average proportion of erythrocytes with micronuclei was 3.20 ± 1.24 ‰ in Russian sturgeon and 5.25 ± 1.18 ‰ in sterlet. The proportion of DNA in the comet tail in erythrocytes of Russian sturgeon was 3,99 %, and in sterlet 6, 48 %. The values of tail moment and Olivet moment were also lower in Russian sturgeon. Among sterlet erythrocytes, a more heterogeneous pattern of DNA damage can be noted. The length of the comet tail in starlet individuals turned out to be lower than in Russian sturgeon: apparently, larger fragments of these molecules were formed when the DNA of starlet erythrocytes was damaged. The physiological state of sterlet individuals can be characterised as normal, and that of the Russian sturgeon as satisfactory, due to the deviations identified in the values of some hematological and biochemical blood parameters.Having studied the influence of the environment on individual sturgeon kept in cage aquaculture conditions in the Volga delta using micronuclear and DNA comet tests, we can conclude that there was no acute genotoxic effect at the time of the study.

The ecological niches (ENM) and spatial distribution (SDM) models of the Russian sturgeon Acipenser gueldenstaedtii Brandt et Ratzeburg (1833), as well as zoobenthos—the main components of this species feeding (Annelida, Mollusca and Crustacea) in the northern part of the Caspian Sea based on long-term monitoring data (1992–2011) and raster layers of the marine environment are presented. The constructed ENM using PCA within the framework of two concepts COUE and ECOUE allowed us to test the hypothesis of conservatism of ecological niches of the Russian sturgeon over time. It was shown that, while under the COUE concept the hypothesis of niche conservatism was fulfilled for one time period of monitoring, under the expanded ECOUE concept, this hypothesis is fulfilled for all monitoring periods. The SDM built by MaxEnt showed that trophic relationships between Russian sturgeon and Azov-Black Sea invaders from different taxonomic groups (Annelida, Mollusca, and Crustacea) in the northern part of the Caspian Sea are quite closely reflected in their spatial distribution. High biomass values of molluscs, crustaceans and ringworms (Annelida) as the main component in the feeding of Russian sturgeon in the western part of the Northern Caspian Sea create preferred conditions for feeding of Russian sturgeon in summer. It has been established that, in the eastern and shallow parts of the Northern Caspian the main components of the feeding are mollusks and crustaceans. [ABSTRACT FROM AUTHOR]

The experiment aimed to evaluate the plasticity of juvenile Russian sturgeon (Acipenser gueldenstaedtii, J. F. Brandt & Ratzeburg, 1833) reared in a floating cage located on a pond. The biological material was 1400 juvenile Russian sturgeon with a mean weight of 9 g/fish and 40 days of age. The intensive rearing system was a 5x5x3 m floating cage in a pond. The fish were fed NUTRA MP-L extruded feed containing 52% crude protein and 20% fat three times a day. The experimental results showed a 64% survival of Russian sturgeon juveniles and the evaluation of productive bioindicators demonstrates high technological plasticity at 50% of the tested group. From the analysis of rearing conditions (environmental and technological), it was concluded that Russian sturgeon juveniles show a certain degree of plasticity depending on the adaptability of the Russian sturgeon to the different environmental conditions which depend principally on the anatomy and physiology of the species Acipenser gueldenstaedtii. [ABSTRACT FROM AUTHOR]

Russian sturgeon (Acipenser gueldenstaedtii) is an endangered fish species and also an important resource for the sturgeon aquaculture industry in Turkiye. Recently, a fatal and persistent bacterial disease occurred in the reared sturgeon kept in a trout farm in Turkiye. The disease outbreak has been with notable external signs including petechial hemorrhages and systemic anemia. This outbreak lasted for six weeks, and cumulative mortality reached around 35.00 - 40.00%. In this study, no parasitic and viral agents were observed in the sturgeons. Citrobacter gillenii was isolated from the diseased fish and identified by biochemical and molecular methods including API 20E and 20NE and 16S rRNA gene region sequencing, respectively. As a result, C. gillenii was identified for the first time in Russian sturgeon in Turkiye. The sequence was also deposited under the Genbank with MW057770 accession number. According to the result of disc diffusion method, bacteria were sensitive to enrofloxacin, streptomycin, amoxicillin and oxytetracycline and resistant to penicillin, trimethoprim/sulfamethoxazole, florfenicol and erythromycin. Also, ampC, sul1 and floR resistance genes were detected in the isolated bacteria. The results of this study provide important information for the diagnosis and treatment of this newly emerged disease of Russian sturgeon. [ABSTRACT FROM AUTHOR]

Simple Summary: The decline in sturgeon populations, including Russian sturgeons, has reached alarming levels, threatening these species with extinction. The requirements for the meat of these fish, caviar and other products used in the textile, medical and food industries are constant or even on the rise. Reproductive biotechnologies seem to be the main solution to these problems, but the many unknowns related to the particularities of the species still place them far from the efficiency reached in some species of domestic animals. The development of fish farms for sturgeons and the intensification of reproductive biotechnologies is the main way in which the natural habitats affected by depopulation can be repopulated and to respond to the consumption and industrial requirements of the population. Our purpose is to contribute with additional novel information on the cryopreservation of sturgeon spermatozoa, as well as the evaluation of semen quality with the aim of developing a cryopreservation technique suitable for commercial breeding facilities. The alarming decline in sturgeon populations doubled by growing demands for sturgeon products, urge us to prevent the loss of these species. Fish stocking in natural habitats and developing fish farms are viable solutions, which can be successfully implemented with the help of reproductive biotechnologies. Despite the fact that semen cryopreservation is admittedly an important step for saving the Russian sturgeon, a reproducible standard method with good results has yet to be identified. Sperm quality assessment is essential for quantifying the impact of cryopreservation on spermatozoa. The purpose of our study was to provide additional information regarding semen cryopreservation and semen quality evaluation for the Russian sturgeon. Our study method is based on the use of two yolk-free extenders (with different cryoprotectants: DMSO and methanol) for freezing semen, using a simple freezing protocol. Parameters such as volume, concentration, motility, morphology and membrane integrity were evaluated. In conclusion, cryopreservation of Russian sturgeon spermatozoa using an extender containing methanol as cryoprotectant led to high egg fertilization percentages (72.67 ± 5.4%) even if the total motility values recorded for thawed semen were quite low (18–25%). Additionally, we identified two optimal stains for morphological studies and morphometry (Spermac stain kit and Trypan Blue Solution). [ABSTRACT FROM AUTHOR]

The present study describes the first case of staphylococcosis causing Staphylococcus pasteuri in Russian sturgeon (Acipenser gueldenstaedtii) in Bulgaria. Clinically, diseased three sturgeons showed hemorrhagic ulcerative skin lesions at the all body surface and internally hyperemia and hemorrhages in the visceral organs and muscle, necrosis in the liver and swollen spleen were observed. Biochemical tests and Vitek 2 system were used to determine the phenotypic characteristics of isolated bacteria in samples taken from liver, spleen and kidney. The isolated bacteria were identified as Staphylococcus sp. Furthermore, 16S rRNA gene of one isolate was partially sequenced and showed 98% identity with the Genbank sequences of Staphylococcus pasteuri. The isolates were determined to be sensitive to sulfamethoxazoletrimethoprim, enrofloxacin and florfenicol, they were resistant to erythromycin, ampicillin and ciprofloxacin. Histopathologically, hemorrhage and lymphocyte groups in the epicardium; intense necrotic areas in the heart; melonomacrophage centers, lymphocyte infiltration around the necrotic hepatocyte cells; necrosis in the kidney; hyperemia and intense hemorrhagic areas in the spleen and melonomacrophage foci, hyperplasia and increase in the number of the goblet cells in the gills were observed. This study represents the first report of S. pasteuri isolation and identification as an agent of diseased Russian sturgeon. [ABSTRACT FROM AUTHOR]

Currently, cryopreservation of sperm is recognized as one of the promising ways to preserve the genetic diversity of fish, not only rare and endangered species, but also aquaculture objects. Scientific research was carried out in the scientific research center "Fisheries" of the S. Seifullin Kazakh Agro Technical University and the JSC "Republican Center for livestock breeding "Asyl Tulik" in 2022. The purpose of the research was to study methods of cryopreservation of Russian sturgeon sperm using cryoprotectors using dimethyl sulfide oxide with a concentration of 5% and 10% and methanol with a concentration of 3% and 8%. In the course of the research, generally accepted methods for assessing and freezing the sperm of the studied object were used. During the experimental work, the method of freezing the reproductive cells of the Russian sturgeon with a 15-minute exposure to -21°C in a box with subsequent immersion in a Dewar vessel was studied. The survival and lifetime of spermatozoa after defrosting were also studied. According to the results of the assessment of the quality of defrosted sperm of the Russian sturgeon, it was found that the most effective cryoprotective medium for cryopreservation is based on methanol with a concentration of 8%. The number of spermatozoa with translational movements in the three groups ranged from 23.8% to 31.2%. At the same time, the lifetime of spermatozoa in this cryoprotective medium was 118s. Methanol with a concentration of 8% provides the best resistance to oxidative stress experienced by cells during freezing. The results of the research make it possible to create a cryobank of the Russian sturgeon gene pool at fish hatcheries to preserve genetic diversity. [ABSTRACT FROM AUTHOR]

The effects of feeding strategies on cytological and biochemical indices in juvenile Russian sturgeon were studied. For this, 180 Russian sturgeons (77 ± 0.33 g) were stocked in three treatments with 20 fish in each tank and three replicates. Different feeding strategies including starvation, restricted feeding and feeding to satiation were assessed. At the beginning, middle and at the end of experiment, blood samples were collected to assay the blood indices. The results showed that at the end of the experimental period, starvation caused a significant decrease in the number of white blood cells (WBC) and mean corpuscular volume (MCV; p0.05). Moreover, the results exhibited that starvation leads to a significant decrease in the plasma glucose and total protein, while a significant increase in cholesterol and triglycerides compared to the other treatments (p

Sturgeons are chondrostean fish critically endangered due to anthropogenic loss and degradation of natural habitat and overfishing for meat and caviar production. Consequently, sturgeon aquaculture has extensively developed lately, being Russian sturgeon (Acipenser gueldenstaedtii) the second most important species reared for caviar production. However, Russian sturgeon aquaculture in subtropical countries, such as Uruguay, confronts difficulties because fish have to endure excessive summertime warm temperatures, which weaken their innate defences facilitating opportunistic infections. To address this problem, we look for identifying putative acute phase proteins (APPs), which might be robust serum biomarkers of both infection and chronic thermal stress, applied to monitoring Russian sturgeon health status in farms. We focused on the C-Reactive Protein/Serum Amyloid P (CRP/SAP) pentraxin since the pentraxin family includes well-known APPs, better characterised in mammals than fish. We identified A. gueldenstaedtii CRP/SAP (Ag CRP/SAP), as a member of the universal CRP/SAP pentraxin sub-family, and studied Ag CRP/SAP involvement in sturgeon response to bacterial challenge and chronic thermal stress, in comparison with A. gueldenstaedtii Serum Amyloid A (Ag SAA), a previously described positive APP. Results showed that Ag CRP/SAP is a constitutive serum component that remained constant upon Aeromonas hydrophila challenge and chronic thermal stress. Contrastingly, serum Ag SAA was subjected to regulation by bacterial and thermal stress challenges, showing a 50-fold increase and 3-fold decline in serum levels, respectively. Overall, results highlight the potential value of Ag SAA, but not of Ag CRP/SAP, as a biomarker of bacterial infection and the need to continue searching for robust chronic thermal stress biomarkers in sturgeons. [Display omitted] • We identified a CRP/SAP pentraxin in Acipenser gueldenstaedtii (Ag CRP/SAP). • Ag CRP/SAP does not act as an APP during bacterial challenge, in contrast with Ag SAA. • Ag CRP/SAP is unchanged, while Ag SAA is down-regulated during chronic thermal stress. • Ag SAA, but not Ag CRP/SAP, is a good candidate for monitoring sturgeon infection. • Neither Ag SAA nor Ag CRP/SAP are good candidates to detect chronic thermal stress. [ABSTRACT FROM AUTHOR]

Purpose.To determine the main parameters of economic efficiency of the use of inactivated baker's yeast as a biologically active additive in the diet of early juveniles of Russian sturgeon. Methodology.The calculations were carried out according to generally accepted methods for economic studies. For economic analysis, we used the actual parameters of economic activity in current industrial aquaculture of Ukraine with the use of RAS, as well as prices for 2015-2016 on relevant materials, products and means of production. Findings. The economic efficiency of introducing 5% and 15% (by weight of the main feed) inactivated baker's yeast into the diet of early juvenile Russian sturgeon grown in the RAS has been established. These concentrations allow achieving more than 70% profitability and reducing the prime cost of onefish to 1.72-1.74 UAH, thereby ensuring high, as compared with other options for feeding, parameters as net (372.96 UAH and 366.86 UAH ) and attributable profit (873.0 UAH and 876.0 UAH). Originality.For the first time, the parameters of economic efficiency of introducing 4 (5%, 10%, 15%, 40% of the weight of the main feed) concentrations of inactivated baker's yeast into the diet of juvenile Russian sturgeon for 28 days, from 25 to 53 days after hatching were analyzed. Practical Value. The study results have both theoretical and practical importance and can be used in further studies aimed at optimizing the cultivation of juvenile sturgeons in RAS and adjusting existing feeding schemes on fish farms.

The alarming decline in sturgeon populations doubled by growing demands for sturgeon products, urge us to prevent the loss of these species. Fish stocking in natural habitats and developing fish farms are viable solutions, which can be successfully implemented with the help of reproductive biotechnologies. Despite the fact that semen cryopreservation is admittedly an important step for saving the Russian sturgeon, a reproducible standard method with good results has yet to be identified. Sperm quality assessment is essential for quantifying the impact of cryopreservation on spermatozoa. The purpose of our study was to provide additional information regarding semen cryopreservation and semen quality evaluation for the Russian sturgeon. Our study method is based on the use of two yolk-free extenders (with different cryoprotectants: DMSO and methanol) for freezing semen, using a simple freezing protocol. Parameters such as volume, concentration, motility, morphology and membrane integrity were evaluated. In conclusion, cryopreservation of Russian sturgeon spermatozoa using an extender containing methanol as cryoprotectant led to high egg fertilization percentages (72.67 ± 5.4%) even if the total motility values recorded for thawed semen were quite low (18–25%). Additionally, we identified two optimal stains for morphological studies and morphometry (Spermac stain kit and Trypan Blue Solution).

The Caspian is a unique drainless water body with no connection to the ocean. This study of the peculiarities of blood cell composition of the Russian sturgeon (Acipenser güldenstädtii) and sevruga (Acipenser stellatus) revealed minor destructive disorders of the blood cells. The number of blood cells also deviated from conditional norms. The study of the leukocyte profile of sturgeons showed the granular forms of leukocytes, band neutrophils and eosinophils, and segmentonuclear neutrophils and eosinophils. The total number of granulocytes in the blood of the Russian sturgeon was increased, which indicated the activation of the body's protective systems in response to the anthropogenic load. In cytomorphological terms, the destructive disorders were revealed. Such phenomena are associated with the ever-increasing anthropogenic load on the biocenoses of natural reservoirs. Summarizing the results, it can be concluded that the quantitative indicators of red blood in the Russian sturgeon (Acipenser gueldenstaedtii) and sevruga (Acipenser stellatus) caught off of the Dagestan coast of the Caspian Sea were reduced in the spring of 2018 compared to 2016, but were in the normal range given in the literature. The concentration of hemoglobin in the Russian sturgeon and sevruga in 2016 was 13% and 15% higher than in 2014, respectively. This phenomenon could be a measure to compensate for the lack of oxygen in various fish tissues and organs. [ABSTRACT FROM AUTHOR]

The goal of this research is to determine temperature threshold limits and duration of overwintering in spawners of beluga (great sturgeon) and Russian sturgeon in the aquaculture farms that would preclude impairment of the generative function. The study performs the assessment of temperature conditions and outcome of overwintering of spawners, egg incubation, and holding of yolk sac larva in beluga and Russian sturgeon in the farms using the warm discharge water from power-producing facilities. The examined parameters have been compared with data obtained from spawners from natural populations in the lower reaches of the Volga River. It has been established that spawners of studied species can survive up to 9 months under conditions of food deprivation at a mean water temperature of 2.2–2.4°С. Both studied species have exhibited an increase in duration of incubation to 24 h and longer compared with individuals from natural populations under conditions of shortened and "comfortable" warm-water overwintering. The duration of egg incubation and holding of yolk sac larva nearest to the conditional norm has been obtained under more severe overwintering conditions of spawners. Desirable conditions include mean water temperature of 3°С and duration of 3–6 months for overwintering of beluga spawners and gradual increase in water temperature from 11 to 14°С and holding of yolk sac larva from 14 to 18°С for the egg incubation. Preferable conditions for overwintering of spawners of Russian sturgeon are mean water temperature of 4°С and duration of 4.5–6.5 months. Preferable conditions for egg incubation of the latter are gradual increase in water temperature from 13 to 16°С and holding of yolk sac larva from 16 to 20°С. [ABSTRACT FROM AUTHOR]

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Length-weight relationships (LWRs), Fulton (K) and relative (Krel) condition factors for Acipenser ruthenus Linnaeus, 1758, Acipenser gueldenstaedtii Brandt & Ratzeburg, 1833 and Acipenser stellatus Pallas, 1771 from the Danube River were estimated. Fish were captured by bottom drifting trammel nets in the period June - August, 2015-2019. A total of 790 specimens were measured and analyzed. More than 80% of the specimens were young of the year (YOY) fish with total length (TL) up to 35 cm. The values of the parameter b of the weight - length relationship for fish with lengths up to 35 cm ranged from 2.433 (A. ruthenus) to 2.859 (A. gueldenstaedtii). For specimens with TL > 35 cm the values of parameter b ranged from 3.227 (A. stellatus) to 3.668 (A. ruthenus). Relative condition factor (Krel) ranged from 1.003 ± 0.020 (A. gueldenstaedtii) to 1.144 ± 0.018 for A. ruthenus. Fulton's condition factor (K) ranged from 0.300 ± 0.003 for A. stellatus to 0.514 ± 0.011 for A. gueldenstaedtii. [ABSTRACT FROM AUTHOR]

Abstract Background Russian sturgeon (Acipenser gueldenstaedtii) is an emerging candidate species in the Korean aquaculture domain owing to its highly valued caviar. Although the embryonic development of this species was previously described, the complete image data on the morphological differentiation of developing embryos have not been yet fully available. Further, with the viewpoint of larval production in hatchery, the effects of temperature on embryonic viability and the temporal window of hatching event have not been extensively studied. Hence, the objective of this study was to provide a complete set of photographic image data on the embryogenesis and also to examine the effects of incubation temperatures on embryonic viability and hatching event in farm-bred Russian sturgeon. Results Typical characteristics of embryonic development including uneven, holoblastic cleavages with unequal blastomeres, followed by the formation of germ layer, neurulation, and organogenesis until hatching, were documented. Under different temperature conditions (12, 16, or 20 °C), viability of embryos incubated at 12 °C was significantly lower as relative to those of 16 and 20 °C incubated embryos. Hatchability of embryos was higher, and the timing of hatching event was more synchronized at 20 °C than at 12 and 16 °C. Conclusion Data from this study suggest that the incubation of Russian sturgeon embryos at 20 °C would be desirable in the hatchery practice with respect to the good hatchability of embryos and the synchronization of hatching events. Additionally, the updated image data for complete embryonic development could be a useful reference guide for not only developmental researches but also artificial propagation of Russian sturgeon in farms.

The antioxidant and cryoprotective efficiencies of a 3,5-di- tert -butyl-4-hydroxyphenyl)methylenediphosphonic acid (MDPA) differ significantly for sperm cells of various species of sturgeon fish (Russian sturgeon, beluga and Stellate sturgeon). The ability of phosphorus-containing phenol MDPA to decrease the level of lipid peroxidation of sperm, beneficial effect on the activity indicators of the sperm of native sturgeon and of the defrosted one after deep freezing as well as on the fertility of sperm cells was shown. [ABSTRACT FROM AUTHOR]

The determination of the carnosine level in fish muscle tissues is helpful for the purposes of general biology and comparative muscle physiology of various fish species; it may be also useful for estimation of the nutritional value of fish products. The mass-spectrometric method of the determination of carnosine in muscle tissues has been improved and tested in this work. The carnosine levels in the muscles of the Russian sturgeon, Siberian sturgeon, sterlet, hybrid of sterlet and kaluga, hybrid of Siberian sturgeon and kaluga have been determined for the first time with this method. The starlet-and-kaluga hybrid, regardless of sex, contains 3.33 times more carnosine than the sterlet (p < 0.01). The female hybrid of Siberian sturgeon and kaluga contains 1.50 times less carnosine than the female Siberian sturgeon (p < 0.1). Since carnosine consumption is important for carnosine biosynthesis in human muscles, the hybridization of sterlet with kaluga is more efficient in terms of nutrition value than pure sterlet breeding, and the hybridization of Siberian sturgeon with kaluga is less effective than sturgeon breeding. [ABSTRACT FROM AUTHOR]

Objective: to determine the levels of essential elements (copper, zinc and manganese) in the liver of Russian and Persian sturgeon and their basic food sites, as well as in the liver of the Caspian seal, which is a functional depot for many metals. Methods. Sampling was carried out according to generally accepted methods, determination of heavy metals produced by atomic-absorption spectroscopy using atomic absorption spectrometer with connection atomizaciej MGA-MD 915. Results. The concentration of zinc in all investigated sites exceed-valid, while zinc is not able to accumulate up the food chain. The level of accumulation of copper was higher than the maximum prescribed only in the liver of the Caspian seal as the holder of a faster metabolism. Manganese in maximum concentration has been found in the liver of the Caspian seal, but does not exceed the permissible values. Since the liver is the primary organ, concentrating this trace element. Conclusions. Accumulation of trace elements depends on the physiological characteristics of an organism, the properties of the trace element and from Wednesday.

Purpose. Determination of the peculiarities of intraspecific genetic polymorphism of Russian sturgeon based on microsatellite DNA markers. Methodology. The polymerase chain reaction (PCR) with the detection of results based on capillary electrophoresis was used for the determination of intraspecific polymorphism of microsatellite DNA Russian sturgeon. Findings. On microsatellite DNA markers was investigated genetic polymorphism of Russian sturgeon (Acipenser gueldenstaedtii Brandt) Black Sea and Dnieper population. It was identified of 56 allelic variants of such DNA-markers investigated as LS-19, LS-68, LS-39, Aox-27, LS-54 and Aox-45. On locus LS-19 allelic variants have been identified, the locus LS-68 was the most polymorphic and consisted of 21 alleles, 11 allelic variants have been identified by the LS-39 locus, and 16 allelic variants have been identified for the LS-54 locus. Aox-27 locus was the least polymorphic microsatellite markers among the study and consisted of 7 allelic variants. For Aox-45 locus 16 allelic variants have been identified. A study of the genetic structure of the Russian Black Sea-Dnieper sturgeon population is not currently been carried out in full and reduced only to the evaluation of the number of identified allelic variants and relative frequency of alleles. Calculations of heterozygosity parameters for Russian sturgeon became complicated definition tetraploid genetic structure of this species on the studied DNA markers. Such studies are an important component in the further work on the conservation of genetic diversity of sturgeon, which will provide an opportunity to carry out the state control over reproduction and preservation of valuable and endangered species under increased anthropogenic impact on natural populations. Originality. For the first time, new data of the peculiarities of the intraspecific genetic polymorphism of Russian sturgeon was obtained using species-specific microsatellite DNA markers. Practical value. The data obtained can be used to control the genetic processes in the populations of Russian sturgeon, as well as to develop a complex of measures to improve the efficiency of breeding and conservation of the structure and species diversity of this sturgeon species.

In the past 50 years, habitat conditions and distribution of sturgeons in the Caspian Sea have significantly changed. The longest term records of sturgeon distribution are obtained for the northern part of the sea, which is extremely important for the feeding of these species. In the present review, we summarize and analyze changes in the distribution of the beluga Huso huso L., 1758; Russian sturgeon Acipenser gueldenstaedtii Brandt, 1833; and stellate sturgeon Acipenser stellatus Pallas, 1771 in the northern part of the sea from 1970 until 2014 and the biotic and abiotic factors of these changes. The effect of the sea-level fluctuations, the biomass of food organisms, and the total abundance of the studied fish species on their distribution is demonstrated. [ABSTRACT FROM AUTHOR]

Albinism is a genetically inherited condition that is caused by a series of genetic abnormalities leading to a reduction in melanin production. Russian sturgeon is one of the most valuable freshwater fish species worldwide, and albino individuals have been found in fish farms. Due to its complicated genome and scarce genome-wide genetic resources, the underlying molecular basis of albinism in Russian sturgeon is unknown. In the present study, we first generated transcriptome profile of Acipenser gueldenstaedtii using pooled tissues, which provided reliable reference sequences for future molecular genetic studies. A total of 369,441 contigs were assembled, corresponding to 32,965 unique genes. A comparative analysis of the transcripts from the skin of albino and wildtype individuals was conducted afterwards. A total of 785 unique genes were differentially expressed, including the upregulation of 385 genes and the downregulation of 400 genes in albino individuals. The expression pattern of 16 selected differentially expressed genes was validated using qRT-PCR. Additional annotation, GO enrichment analysis and gene pathway analysis indicated that the melanogenesis pathway may be interrupted in albinism. Eight potential causative genes that were highly likely to be responsible for sturgeon albinism were identified, including Dct , Tyrp1b , Slc45a2 , Ctns , Pmela , Pmelb , Cd63 , and Bloc1s3 , which were found to be significantly down-regulated in albino Russian sturgeon. Moreover, a sliding window analysis of the ratio of nonsynonymous to synonymous nucleotide substitution rates (Ka/Ks) ratios indicated that seven out of the eight genes underwent positive selection during evolution. Our results provide a valuable basis for understanding the molecular mechanism of albinism in fish species and will facilitate future genetic selection and breeding of sturgeon with market-favored traits in aquaculture. [ABSTRACT FROM AUTHOR]

Abstract 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. Graphical abstract Interaction pathways between key genes involved in sex differentiation. The dotted arrows indicate indirect influences, the solid arrows indicate up-regulation of the factor, the solid lines with a vertical end indicate down-regulation of the factor, blue text indicates genes associated with male sex differentiation, and pink text indicates genes associated with female sex differentiation. Unlabelled Image Highlights • The brain is a central player in initiating sex differentiation in sturgeon. • Dmrt1 and foxl2 play major roles in early sex differentiation. • Atypical gene expression profiles were observed in the brains of the Russian sturgeons examined, indicating feminization. [ABSTRACT FROM AUTHOR]

Five isonitrogenous diets were formulated with graded alpha‐linolenic acid (LNA) levels (0, 5, 10, 15 and 20 g/kg) to investigate LNA requirement of juvenile Russian sturgeon Acipenser gueldenstaedtii. Weight gain and specific growth rate of fish fed LNA5 and LNA10 were significantly higher than those in other groups, while the feed conversion ratio of these two groups was lower than others. Dietary LNA increased n‐3 polyunsaturated fatty acid and n‐3/n‐6 ratio, but decreased saturated fatty acid contents in the liver. DHA in the fish tissue also increased with the increased dietary LNA. The superoxide dismutase activity was highest in fish fed LNA5. Fish fed LNA10 showed the highest catalase activity and the highest malondialdehyde content. A 459‐bp fragment of Δ6 fatty acid desaturase and a 474‐bp fragment of elongases of very long chain fatty acids 5 were cloned and analysed. The expressions of these two genes were higher in fish fed LNA15 and LNA20. The highest hepatic lipase activity occurred in fish fed LNA 20, and the malate dehydrogenase activity peaked in the LNA5 group. Based on SGR and FCR, the range of optimum dietary LNA concentration for juvenile Russian sturgeon is recommended at 6.85–10.69 g/kg. [ABSTRACT FROM AUTHOR]

Russian sturgeon (Acipenser gueldenstaedti Brandt & Ratzeburg, 1833) is one of the major commercial sturgeon species, but there is no adequate information and previous‐published about population dynamics and stock assessment of this species in the southern Caspian Sea. This paper examines the age structure, growth parameters, maturity, age at first capture, optimum length, natural and fishing mortality and amount of biomass in the southern Caspian Sea (Iranian waters), during a two decades time series period from 1990–1991 to 2008–2009. For a pooled data, the growth parameters were estimated as L∞ = 214.0 cm, K = 0.054, t0 = −4.5 year. Size at fifty percent sexual maturity was at FL = 118 cm for females and 113 cm for males. The age at first capture (tc) estimated to be 12.1 years. In the catch composition, bulk of the catch (75%) belonged to 13–17 years old. The instantaneous coefficient of natural mortality (M) was estimated as 0.120 year−1 and the instantaneous coefficient of fishing mortality (F) varied during the 19‐year period between 0.130 to 0.505 year−1. The biomass showed a descending trend from 1,941.2 mt in 1990–1991 collapsed to about 55 mt in 2004–2005, and then decreased to the lowest level and represented 18.5 mt in 2008–2009. The result revealed that, the stock of Russian sturgeon is being over‐fished. We concluded that to manage the sturgeons stocks, a coordinated regional and international effort are needed to provide immediate implementation of stock enhancement and management in the Caspian Sea. [ABSTRACT FROM AUTHOR]

By using PASS online web resource, it was predicted that phosphorus-containing derivatives of 2,6-di-tert-butylphenol had high probability to possess antioxidant activity and to act as active oxygen metabolite "traps" and heavy metal antidotes. The values of the acute toxicity index of phosphorus-containing phenols for rats, aquatic organisms, and bioaccumulation factor, calculated by the GUSAR programme, indicate potentially low toxicity. The results of the forecast are comparable with the data of experimental studies in vitro and in vivo experiments. [ABSTRACT FROM AUTHOR]

The Russian sturgeon, Acipenser gueldenstaedtii, is a critically endangered fish species. Hatcheries are operated in several countries within its natural range to produce stocking material for release into the wild and also for aquaculture purposes (caviar and meat production). An appropriate genetic broodstock management (plan or strategy) is required to avoid negative effects, e.g., admixture and hybridization of genetically differing stocks or loss of genetic variability due to inbreeding and genetic drift. Therefore, 11 tetrasomic microsatellite loci were newly isolated from the Russian sturgeon genome and arranged together with an already known locus into four multiplex PCR sets. These microsatellites were used to characterize three groups of hatchery juveniles from Germany (aquaculture production), Turkey, and Romania (production of stocking material) as well as a group of wild-caught adults from the Danube River, Romania. Based on the variability within groups, measured by the mean number of alleles per locus and expected heterozygosity, and the differentiation between groups, measured by Nei’s GST and genetic distance D, the ability of the 12 loci to detect unwanted reductions in genetic variability within hatchery juveniles and to differentiate between groups could be demonstrated. This set of loci can also be used to identify those pairs of spawners that transmit the highest possible genetic variability to the next generation. [ABSTRACT FROM AUTHOR]

ABSTRACT In the study, the immunostimulant effects of rosehip (Rosa canina) on the health indicator hematological and non-specific immune parameters of Mycobacterium salmoniphilum-infected sturgeon were investigated. The rosehip was applied in the ratios of R5 (5%), R10 (10%), and R15 (15%) in three repetitions. After a 35-day feeding period, the fish were infected with M. salmoniphilum and analyzed after day 7, when symptoms were observed at elevated levels. Erythrocyte, erythrocyte indices, hemoglobin, hematocrit, leukocyte levels and the non-specific immune parameters including lymphocyte, monocyte, eosinophil, neutrophil, cytokines, phagocytic activity levels were comparatively examined using positive and negative control groups. The evaluations revealed that the RBC, Hb, Hct and WBC counts in the R15 group were significantly higher than those of the C+ group. Moreover, depending on the level of the immune response of the fish, among the immune parameters, significant increases in the lymphocyte, monocyte, cytokine, and phagocytic activity levels were observed in the R15 group. The results showed that the hematological and immune response to M. salmoniphilum infection was stimulated significantly in the 15% rosehip-fed fish. Hence, the effective dose of rosehip in fish was determined to be 15% and rosehip is suggested as an alternative to currently recommended immunostimulants.

In work temperature adaptations of enzymes of a mucous membrane of intestines of Russian, Siberian sturgeons and their hybrid ROLO are investigated. It is confirmed that temperature adaptations of digestive system poikilothermic organisms are realised mainly thanks to reorganisations of fermental systems. The assumption that evolutionary adaptation of hydrolytic function of intestines of fishes to temperature conditions of an inhabitancy takes place, apparently, is made.

Complex research of characteristics of some enzymes which are carrying out membrane hydrolysis of food at a spoonbilled cat and Russian sturgeon is carried out. High thermostability enzymes the squirrel of all investigated enzymes is marked.

The paper presents the results of analysis of the state of Caspian sturgeon stocks in long-term aspect. The main factors causing the decline in the state of Caspian sturgeon stocks are considered. It is noted that at the present stage when natural resources of the Volga-Caspian basin have been actively developed by man such factors as human impact and geopolitical changes in the region arise in the general succession of negative factors. It is shown that measures aimed at restoration of these valuable fish populations do not fully solve the problem.

To study the role of somatotropin (ST) in osmotic regulation of anadromous acipenserids, the dynamics of hormone concentration in blood serum of juvenile Russian sturgeon Acipenser gueldenstaedtii Brandt (age 4 months, average length 16.9 cm, average weight 17.1 g) during fish adaptation to hyperosmotic medium of 12.5‰ salinity (403 mOsm/l) was evaluated for the first time. During the first 24 h after the transfer of fish from freshwater to hyperosmotic medium, an increase of ST serum concentration (up to 2.06 ± 0.09 vs. 0.98 ± 0.03 pg/ml in control fish from freshwater) was observed. This increase occurs concurrently with an increase in blood serum osmolarity (up to 386.2 ± 4.0 mOsm/l vs. 218.5 ± 4.9 mOsm/l in control) resulting from the diffusion of water from the organism under new osmotic gradient, as well as with the period of morphofunctional remodelling of the osmoregulatory system corresponding to the transition of fish to hypoosmotic regulation. 24 h after the start of the experiment, fish that have shifted to hypoosmotic regulation display the adaptive decrease in osmolarity (aimed at maintaining the relative constancy of blood serum) and the ST concentration (down to 1.18 ± 0.16 pg/ml after 120 h, comparable with that in the control fish). It is concluded that during transition of juvenile Russian sturgeon to hypoosmotic regulation, ST becomes involved in morphofunctional remodelling of the osmoregulatory system concurrently with other components of this system. ST-immunopositive cells were revealed in the dorsal part of mesoadenohypophysis of Russian sturgeon juveniles by immunochemical method. [ABSTRACT FROM AUTHOR]

The article focuses on a study based on analyzing effect of luteinizing hormone-releasing hormone analogue and carp pituitary hormones on Russian sturgeon's sperm characteristic. It mentions that Gonadotropin-Releasing Hormone (GnRH) is also called Luteinizing-Hormone Releasing Hormone (LHRH) due to the LH-releasing activity, is synthesized in a particular area of the brain and it is responsible for the regulation and the releasing of gonadotropins (GTH).

Polysubstituted derivatives of sterically hindered phenol were found to reduce accumulation of hydroperoxides in the lipid extract from fish feed after 8-week incubation. Feeding of juvenile Russian sturgeon with fish food containing these compounds showed no negative effect on hydrobionts. Both in vivo and in vitro experiments revealed inhibition of hepatic lipid oxidation in juvenile Russian sturgeon in the presence of new bis-pyrrolidine derivatives of 2,6-di-tert-butylphenol. A reliable positive correlation was observed between the concentration of hydroperoxides in the lipid extract from fish feed and accumulation level of secondary enzymatic oxidation products of hepatic lipids in hydrobionts. [ABSTRACT FROM AUTHOR]

Russian ( Acipenser gueldenstaedtii), Persian ( A. persicus) and Siberian ( A. baerii) sturgeons are closely related ‘Ponto-Caspian’ species. Investigation of their population structure is an important problem, the solution of which determines measures for conservation of these species. According to previous studies, ‘baerii-like’ mitochondrial genotypes were found in the Caspian Sea among 35% of Russian sturgeon specimens, but were not found in Persian sturgeons. This confirms genetic isolation of the Persian sturgeon from the Russian sturgeon in the Caspian Sea. However, in order to clarify the relationships of these species it is necessary to analyze nuclear DNA markers. The amplified fragment length polymorphism (method) allows estimating interpopulation and interspecific genetic distances using nuclear DNA markers. In the present study, four samples were compared: Persian sturgeons from the South Caspian Sea, Russian sturgeons from the Caspian Sea and the Sea of Azov, and Siberian sturgeons from the Ob’ River, which are close to the latter two species, but are also clearly morphologically and genetically distinct from them. For the amplified fragment length polymorphism (AFLP) method, eight pairs of selective primers were used. The analysis revealed that the Siberian sturgeon has formed a separate branch from the overall Persian-Russian sturgeons cluster, which was an expected result. In addition, the results showed that the Caspian Russian sturgeon is closer to the Persian sturgeon from the Caspian Sea than to the Russian Sturgeon from the Sea of Azov. The present DNA marker data confirm that despite the genetic isolation of the Persian sturgeon from the Russian sturgeon in the Caspian Sea, the Persian sturgeon is a young species.

Russian ( Acipenser gueldenstaedtii), Persian ( A. persicus) and Siberian ( A. baerii) sturgeons are closely related ‘Ponto-Caspian’ species. Investigation of their population structure is an important problem, the solution of which determines measures for conservation of these species. According to previous studies, ‘baerii-like’ mitotypes were found in the Caspian Sea among 35% of Russian sturgeon specimens, but were not found in Persian sturgeons. This confirms genetic isolation of the Persian sturgeon from the Russian sturgeon in the Caspian Sea. However, in order to clarify the relationships of these species it is necessary to analyze nuclear DNA markers. The amplified fragment length polymorphism (method) allows estimating interpopulation and interspecific genetic distances using nuclear DNA markers. In the present study, four samples were compared: Persian sturgeons from the South Caspian Sea, Russian sturgeons from the Caspian Sea and the Sea of Azov, and Siberian sturgeons from the Ob’ River, which are close to these two species, but are also clearly morphologically and genetically distinct from them. For the AFLP method, eight pairs of selective primers were used. The analysis revealed that the Siberian sturgeon has formed a separate branch from the overall Persian-Russian sturgeons cluster, which was an expected result. In addition, the results showed that the Caspian Russian sturgeon is closer to the Persian sturgeon from the Caspian Sea than to the Russian Sturgeon from the Sea of Azov. The present DNA marker data confirm that despite the genetic isolation of the Persian sturgeon from the Russian sturgeon in the Caspian Sea, the Persian sturgeon is a young species.

• Daidzein may have some hepatoprotective effect, although it increases apoptosis. • Genistein contributes to the development of many pathological hepatic lesions. • Coumestrol induces DNA strand breaks, but not hepatocyte apoptosis. • The key issue for sturgeon liver injuries prevention is to limit dietary lipids. In the last two decades, much controversy has grown over the use of soybean products in aquafeeds, especially for carnivorous fish like sturgeons. One point of discussion is the effect of soybean phytoestrogens on fish health. There are many aspects of phytoestrogen utilization in aquafeeds, therefore, the aim of this study is to verify if common legume phytoestrogens can affect juvenile cultured sturgeon erythrocyte and hepatocyte genotoxicity and cause liver pathology. Russian sturgeons were fed from 100 till 365 dph 1 1 Days post hutching. with daidzein, genistein, and coumestrol supplemented diets in concentrations: 10, 0.05 and 0.001 g kg−1 of feed, respectively. The SCGE 2 2 Single Cell Gel Electrophoresis (comet assay). method combined with qPCR of three genes involved in DNA repair and genome maintenance, namely cyp1a1, gaad45a and p53 were analyzed. The results were compared with histopathological evaluation of liver tissue. In fish fed with coumestrol supplemented diet, DNA strand damage was the highest in both erythrocytes and hepatocytes, however, simultaneously the lowest level of oxidative DNA damage was found. Additionally, slightly elevated expression of the p53 gene was observed along with a decreased number of apoptotic hepatocytes, which suggests that low concentration of coumestrol may support DNA repair mechanisms in the liver. Although, daidzein showed a preventive effect only against fibrosis. Isoflavones did not show a significant effect on DNA damage in studied cells. Genistein was found to increase macro- and microvesicular steatosis, portal hepatitis and fibrosis, indicating its negative role in the development of liver injuries. Daidzein alleviated some sturgeon liver damage, especially macrovesicular steatosis and interface hepatitis. However, it increased hepatocyte apoptosis, which may suggest daidzein potentially inducing liver injury, though not manifested by other histopathological lesions. Therefore, it can be concluded that at given concentrations, the tested phytoestrogens did not show clearly hepatoprotective effect in sturgeons. [Display omitted] [ABSTRACT FROM AUTHOR]

Russian sturgeon ( Acipenser gueldenstaedtii) has been successfully farmed in Uruguay for the past ten years. However, during the Uruguayan summer fish endure high water temperatures and increased bacterial infections that threaten aquaculture. Our understanding of sturgeon's immune system and its interplay with environmental factors like temperature is almost unknown. This study analysed the way in which seasonal variations affect enzymatic blood components of Russian sturgeon's innate defences, including the serum alternative complement pathway (ACP), ceruloplasmin (Cp) and lysozyme activities. Results showed that summertime conditions in the farm altered these defences in different ways, inducing a significant decrease in ACP and Cp, and an increase in lysozyme. In addition, serum levels of total protein and cortisol decreased in summer, suggesting a chronic stress response was induced in parallel. Subsequently, we analysed whether the increase in water river temperature during summer could account for the observed results. To that end, we acclimated juvenile sturgeons to mild (18 °C) or warm (24 °C) temperatures for 37 days. Like in summer, sturgeons exposed to 24 °C showed lower levels of serum ACP, Cp and total proteins, together with a progressive decrease in body weight and increased fish mortality. Administration of an immunostimulant containing Se and Zn slightly reverted the temperature-induced effects on sturgeon's defences. Altogether, our study provides novel data on various physiological parameters of the Russian sturgeon and highlights the impact warm temperature has on stress and innate immunity in this chondrostean fish. [ABSTRACT FROM AUTHOR]

The aim of this paper was to analyze some morphometric characteristics and the correlation between them for Russian sturgeon juveniles (Acipenser gueldenstaedtii) reared in a recirculating aquaculture system fed at different fed with different ratio: 1% body weight (BW), 1.5% BW, 2% BW and ad libitum feeding (which was around 2.8% BW).Fish, with an average body mass around 248.194 ± 1.59 g. Following biometric measurements were made for each fish, including weight (W), total length (TL), standard length (SL), fork length (FL), maximum body depth (last depth of caudal peduncle, H); preanal distance (AD), predorsal distance (PD), length of head (C), preorbital distance (PO), length of pectoral fin (LPF), interorbital distance (ID), maximum width of head (MH), width of mouth (WM), width of the head at the level of the mouth (WHM). The obtained results showed significant differences between all morphometric measurements (p<0.05) for all the experimental variants, emphasizing that in the ad libitum feeding all morphometric measurements were significantly higher than in the other experimental variants. In order to highlight more eloquent these differences, were developed some linear regressions between the morphometric measurements and significant positive correlation (p<0.05) between dependent and independent variables were found. [ABSTRACT FROM AUTHOR]