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The results of formation of broodstocks and commercial productive stocks of sterlet (Acipenser ruthenus Linnaeus, 1758), beluga (Huso huso Linnaeus, 1758) and bester (Huso huso × Acipenser ruthenus) on the Samukh commercial farm in Republic of Azerbaijan are presented. In 2019, for the first time in the history of fishbreeding in Azerbaijan, a progeny was received from grown “from eggs” sterlet females at age of 4 years at the Samukh fish farm using RAS. The mature eggs were stripped using minimally invasive microsurgery method by S.B. Podushka. After the egg collection sterlet females were transferred into holding basins for rehabilitation, further growing and second maturation. The total number of sterlet larvae from domestic broodstock exceeded 100 thousand. An ovulated beluga eggs were received from grown in aquaculture females at the age of 15 in December 2020. In result of fertilization of beluga eggs by sterlet sperm, hybrid (♀ Huso huso × ♂ Acipenser ruthenus) progeny was obtained and successfully grown on the farm. In future the domestic bester broodstock would be formed. The received data demonstrated that functional development of fingerlings and juveniles of sterlet “from eggs” sterlet farm took place without noticeable deviations from physiological normal physiological indices. The number of red blood cells per unit volume of blood increased in ontogenesis. On the contrary the number of white blood cells had seasonal variability and did not directly depend on the age of young sterlet.

The dynamics of physiological and biochemical parameters of blood and urine in the process of gonad maturation in females of the sterlet × beluga hybrid (Acipenser ruthenus L., 1758 × Huso huso L., 1758) grown using CWSI technology is studied. It is shown that, when this technology is applied, features in functional changes that accompany the gonadogenesis of female hybrids appear, distinguishing them from those of fish from natural populations. At the same time, the direction of the generative exchange aimed at the formation of gametes is generally the same as in females from natural populations. However, the evidence of this process, reflecting its intensity at different stages of gonad development, is not as distinct as in females migrating to spawn. Possible reasons for high levels of the studied physiological and biochemical parameters in blood of females of the hybrid after the end of their artificial wintering are discussed.

Three-year-olds (15 individuals) and eight-year-olds (15 individuals) of the sterlet × beluga hybrid (Asipenser ruthenus × Huso huso), grown in mesh cages in the Volga delta, were studied in the third decade of September 2019 in order to establish the functional state of the organism by blood parameters reflecting the state erythron and metabolism. The results of the performed study found that the erythron system differs in a smaller number of blood erythrocytes in eight-year-olds (0,76 ± 0,04 × 1012l –1) compared with three-year-olds (0,98 ± 0,04 × 1012l –1), in the absence of differences in blood hemoglobin and serum iron. Analysis of the state of protein metabolism showed that the content of total protein and the activity of ASAT in serum were the same in the groups. The serum albumin content in eight-yearolds was 17,87 ± 0,92 g/l, which was significantly less than in three-year-olds (24,15 ± 1,78) (p < 0,05). The relative content of serum albumin (as a percentage of total protein) in eightyear-olds was 51,04 ± 3,12%, which is less than in three-year-olds (72,51 ± 6,04%) (p < 0.01). The serum ALAT activity in eight-year-olds was lower than in three-year-olds (2,33 ± 0,16 and 2,93 ± 0,17 μkat/l, respectively) (p < 0,05). The results of the study of lipid metabolism revealed that serum cholesterol in eight-year-olds (2,62 ± 0,11 mmol/l) is less than in three-year-olds (1,39 ± 0,05) (p < 0,05). However, the serum triglyceride content did not differ between threeyear-olds and eight-year-olds, being 3,50 ± 0,07 and 3,26 ± 0,13 mmol/l, respectively. The glycemic values in three-year-olds and eight-year-olds are significantly different and amount to 1,80 ± 0,08 and 1,42 ± 0,11 mmol/l, respectively (p < 0.05). The results of the study can be used to assess the state of physiological adaptation of the hybrid and to determine the reference values of the parameters of the erythron system and metabolic homeostasis.

To determine the effect of coriander on beluga, Huso huso, a total of 150 fish (250 ± 2 g) were fed a diet containing 0, 5, 10, 15, or 20 g kg−1 of coriander for 60 days (Phase 1). The fish were th...

The in vivo effect of 11-ketotestosterone (11KT) on transcript levels of the gonadotropin receptors (fshr and lhr) and sex differentiation-related genes (dmrt1 and foxl2) was examined in the ovaries of immature female beluga. For this purpose, six fish were treated with implants containing 2.5 mg 11KT and a placebo group of six females of the same age and gametogenic stage were given a blank implant. The implants were intraperitoneally inserted into 4-year-old females at the previtellogenic stage (mean body weight 5580 ± 165 g) and maintained under culture conditions for 8 weeks. Ovary samples for gene expression analysis of lhr, fshr, dmrt1 and foxl2 were collected by biopsy at 3 and 8 weeks post implantation. Diameters of oocytes increased in response to 11KT treatment, both at 3 and at 8 weeks post implantation, but no obvious changes were evident in cytology. Three weeks of 11KT treatment did not affect target gene expression, but a tendency for a time-dependent decrease of lhr and dmrt1 mRNA levels was observed in both treatment and placebo groups. By 8 weeks of treatment, however, 11KT implants provoked the upregulation of fshr and foxl2 transcript levels. Furthermore, lhr and dmrt1 transcript abundances recovered by 8 weeks of exposure in both blank- and 11KT-implanted beluga. These results suggest that 11KT, either directly or indirectly, may affect gametogenesis and regulate some key components of the reproductive axis in female beluga.

There is a significant lack of data for the biological parameters of beluga or great sturgeon, the largest fish in the Caspian Sea. The age, growth and fisheries indices for the stock status of beluga was investigated in the south Caspian Basin of Iran between 1990 and 2011. Fork lengths ranged between 113-420 cm and weights from 8.0 to 725.0 kg. The growth parameters were L ∞ = 440 cm, K = 0.027 year−1, t 0 = − 5.8 years. The age at first capture (t c ) was 13.1 years. The long-term age composition data showed age up to 63 years, and the ages 12-19 years comprised 76.7% of the total catch. The generation length was 33 years. The values of “KF” were close to 1 or >1, indicating that beluga sturgeon is in a favorable condition in the southern Caspian Sea. The length distribution showed that 24.2% of the catch is comprised of juveniles. Based on the age structure and age at first maturity, recruitment and growth overfishing occurred in beluga stocks. Therefore, increased length or age at first capture in future fishery policies should be implemented. The mega-spawners represented 4.4% of the fish captured and revealed an unhealthy population structure.

The objective of the present study was to investigate the effects of dietary supplementation with zinc oxide (ZnO) and chitosan–zinc nanoparticles (chitosan–ZnO NPs) on biochemical, immunological, and antioxidant biomarkers in blood of juvenile belugas (Huso huso). The beluga juveniles with initial weight of 287 ± 46 g were fed with eight experimental diets containing 0 g kg−1 ZnO (the control diet); 10, 20, and 40 mg kg−1 ZnO; and 10, 20, and 40 mg kg−1 chitosan–ZnO NPs and 36 mg kg−1 chitosan. After 28 days of culture, the fish were fed with ZnO and chitosan–ZnO NP–supplemented diets showed a more significant increase in total antioxidant capacity (TAC), superoxide dismutase (SOD), catalase (CAT), glutathione (GSH), glutathione peroxidase (GPX), and glutathione S-transferase (GST) activity (p 0.05) in malondialdehyde (MDA) and glucose level in all treatment groups. The results showed that with increasing levels of ZnO and chitosan–ZnO NPs, alternative complement activity (ACH50), and total immunoglobulin, total protein, albumin, and lysozyme had a significant increase in fish fed with ZnO and chitosan–ZnO NP–supplemented diets compared to the control group (p 0.05), while the levels of LDH enzyme activity, urea, and creatinine decreased by increasing both ZnO and chitosan–ZnO NP levels. These results demonstrated that dietary chitosan–ZnO NPs could improve the health status, immune function, and antioxidant capacity of the cultured beluga juvenile.

The eastern part of the Black Sea and its tributaries are suitable habitats for several sturgeon species, among which Acipenser gueldenstaedtii, A. stellatus, A. nudiventris, A. persicus, A. sturio, and H. huso are well documented. However, different threats have led these species to a dramatic decline, all of them are currently listed as Critically Endangered, and some Locally Extinct, in that area. We tested 94 wild sturgeon samples from the Black Sea and Rioni River by analyzing the mitochondrial Control Region and nuclear markers for hybrid identification. The data analyses (1) assessed mitochondrial diversity among samples, (2) identified their species, as well as (3) indicated instances of hybridization. The data collected, besides confirming a sharp decrease of catches of Beluga and Stellate sturgeon in recent years, also revealed four juvenile hybrids between Russian and Stellate sturgeon, providing the first evidence of natural interspecific hybridization in the Rioni. The present communication raises concerns about the status of sturgeon species in this area and underlines the urgent need for conservation programs to restore self-sustaining populations.

The effects of different extraction methods (I, II, III, and IV), including two levels of acetic acid (0.2–2.0 N) and sodium hydroxide (0.2–2.0 N), on the skin gelatin extracted from Caspia...

In the present study, oxygen consumption of two sturgeon species, beluga (Huso huso), sterlet (Acipenser ruthenus), and their hybrid reared in a recirculating aquaculture system were compared over body intervals from 54–107 g to determine the interspecific variation of metabolic rate. Metabolic rates were measured using the intermittent-flow respirometry technique. Standard oxygen consumption rates (SMR, mg O2 h−1) of sterlet were 30% higher compared with beluga and 22% higher compared with bester hybrid. The routine metabolic rate (RMR, mg O2 h−1) averaged 1.58 ± 0.13 times the SMR for A. ruthenus, 1.59 ± 0.3 for H. huso, and 1.42 ± 0.15 for the hybrid bester. However, the study revealed no significant differences (p &gt, 0.05) between mean values of SMR and RMR for beluga and bester hybrid. The scaling coefficient reflected a closed isometry for the hybrid (b = 0.97), while for the purebred species the coefficient of 0.8 suggests a reduction in oxygen consumption with increasing body mass. These findings may contribute to understanding the differences in growth performances and oxygen requirements of the studied species reared in intensive aquaculture system.

The sturgeon group is an economically important group in the world due to the production of caviar, and they are also a suitable old species for researching on the evolution of the mitochondrial genome. In H.huso sequencing, we identified a distinct genome organization relative to other species that has never been reported before. In this specie, the mitochondrial genome consisted of 13 genes encoding proteins, 22tRNA and 2rRNA, and two non-coding regions that followed other vertebrates. In addition, H.huso had an pseudo tRNA-Glu between ND6 and Cytb and also had a 52-nucleotide tandem repeat with two replications in the 12SrRNA. This duplication event is related to the slipped strand during replication, which can remain in the strand as a result of mispairing during replication. Furthermore, an 82 bp repeat sequence with three replications was observed in the D-loop control region, which is usually visible in different species. Regulatory elements are also visible in the control region of the mitochondrial genome that include termination sequences and conserved regulatory blocks. Genomic compounds showed the highest conservation in terms of rRNA and tRNA, while protein-encoded genes and non-encoded regions had the highest divergence. The mitochondrial genome was phylogenetically assayed using 13 protein-encoding genes.

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.

The swimming ground speed and swimming depths of beluga sturgeon (Huso huso) and stellate sturgeon (Acipenser stellatus) were investigated using ultrasonic telemetry between 2011 and 2017 in the Lower Danube River (river kilometer (rkm) 0 Sulina-rkm 1075 Bazias). Acoustic telemetry receivers VR2W and V16TP tags (Vemco, Canada) were used to collect data about sturgeon migration behavior in the Lower Danube River between the Black Sea and the Iron Gate II dam. The tags, equipped with depth and temperature sensors, provided data about beluga and stellate sturgeon migration periods, swimming speeds, and depths. Twenty-three beluga sturgeon (184-245 cm TL) and twenty-one stellate sturgeon (92-135 cm TL) were ultrasonically tagged and passively tracked using hydrophone receivers installed in the river between rkm 71 and rkm 860. Three tagged beluga sturgeon returned after 2 and 5 years and two stellate sturgeon returned after 2 years since the time of their initial release in the river. This study provides, for the first time, further details concerning beluga sturgeon and stellate sturgeon migratory behavior patterns, traveled distances, swimming depths, and their swimming ground speeds during spawning migration.

Fish and fishery products are important parts of the human diet, but the microbial, chemical, and physical deteriorations limit their shelf life. Using the modified atmospheric packaging system and edible coatings is one of the main procedures to improve the shelf life of fish. In this research, the effect of chitosan nanoparticles (CNPs) loaded with fennel essential oils along with modified atmosphere packaging (MAP) system on chemical, microbial, and sensorial properties of Huso huso fish fillets during storage at fridge were evaluated. The results showed that coating fish fillets with CNPs and fennel EO significantly reduced the peroxide value, total volatile nitrogen, and thiobarbituric acid value compared with the control samples. Microbial analyses showed a lower number of mesophilic, psychotropic, pseudomonas, and lactic acid bacteria in coated fillets compared with control and MAP packaging. Fish fillets coated with CNPs and EO showed high acceptability in all sensorial attribute through the storage. It can be concluded that using CNPs and fennel EO along with MAP packaging can enhance the shelf life for H. huso fillets up to 18 days in the fridge.

All six sturgeon species naturally occurring in the Danube River from the Black Sea (BS) to the upstream reaches in Germany today are under severe pressure and classified as either vulnerable, critically endangered or already extinct in the Danube River Basin (DRB). This sharp decline of populations is the result of two major drivers: habitat alteration and unsustainable harvest. The Danube River Basin can be divided in three functionally separated sections by its hydromorphology and character: The Lower Danube (LD) and BS, now also separated ecologically from the Middle Danube (MD) by two hydropower stations at the Iron Gate gorge, 800 km from the sea, currently restricting the remaining anadromous sturgeon species (A. gueldenstaedtii, A. stellatus, Huso huso) to the LD and BS also restraining migrations of potamodromous species. The Upper Danube (UD) is nowadays disconnected from the approx. 850 km long MD by Gabcikovo Dam. The UD itself, as well as many tributaries along the Danube, are fragmented by numerous barriers, leaving no more than a total of 300 km free flowing river out of 700 km. Overharvest led to disappearance of most sturgeon species in the UD already in the Middle Ages, with populations in the MD following in the subsequent centuries. Today the potamodromous sterlet (A. ruthenus) still exists in small decreasing populations in the UD and MD basins, where its occurrence is supported by stocking. Most probably the potamodromous ship sturgeon (A. nudiventris) is extirpated in the whole basin. The Danube basin comprises 19 countries, being the most international river basin in the world, rendering coordinated conservation efforts a challenge. Strategic guidelines for the conservation of the Danube sturgeons are available in form of several action plans, but implementation remains insufficient as of yet. This paper attempts an analysis of the potential for sturgeon restoration in the UD and MD basin and highlights the need for concerted approaches when it comes to ex situ actions and reintroductions.

We studied sex and maturity stage of great sturgeon with different reproductive stages using sex steroid hormones concentrations in blood plasma, gonad histology and laparoscopic technique. One hundred sixty farmed great sturgeons at ages between 1 and +12 years and weight ranged from 0.45 to 49.65 kg (80 males and 80 females, 20 fish of each maturity stage) were selected. Mean sex steroid levels showed that testosterone (T) and 11ketotestosterone (11KT) in plasma varied significantly by sex and maturity stage. But the mean concentrations of 17B‐estradiol (E2) varied significantly only between the maturity stages I and III. All fish were sex determined by laparoscopy and histology examinations confirmed it. Our results showed, however laparoscopy was effective method for sex determination at four maturity stages, but young fish at maturity stage I required gonadal histology examinations to confirm sex. The present study results showed that some steroid sex hormones (T and 11KT) can be used to determine sex and reproductive stage in great sturgeon, especially in later maturity stages. Although the laparoscopy may be stressful and cause small scars on the body of the fish, but it is a fast, effective, and cheap method for sex and maturity stage assessment (30 to 40 s for each fish), especially at later maturity stages. Histology of gonads is a very accurate, but it is an invasive method and not a suitable technique for commercial purposes. Histology is more suited for scientific studies than commercial application. The ability to use minimally invasive methods for sex determination will assist broodstock management and conservation in sturgeons.

Since sturgeons do not show clear sexual dimorphism particularly when are small in size, attempts were made to determine the best methods to identify early sex in farmed beluga sturgeon (Huso huso). The present study describes the ultrasonography, small surgery and plasma steroid hormone methods to determine gender at 18‐month fish, which no research has been conducted yet into the fish at such small ages. Twenty one cultured beluga sturgeon's gonad were imaged using an ultrasonograph unit with a 9–13 MHz linear transducer. Overall accuracy of sex determination using ultrasonography was 80.95%. Plasma testosterone (T) levels were significantly higher in males than in females whereas 17α,20βOH‐P levels were significantly higher in females than in males. Testosterone (T) and 17α,20βOH‐P were not correlated with morphometric parameters (TL, SL, W, CF) in 18‐month beluga sturgeon. Results of this study indicated that sex could be identified by each of ultrasonography, small surgery and analysis of blood plasma in such a small size (18‐month). Although direct observation was more efficient than the other methods, ultrasonography was the simplest and cost‐effective tool in sturgeon's sex determination compared to other methods, and the least invasive.

This study has been done on evolution and morphology of hindbrain structure, during larvae life from 1 to 54 dph on Huso huso. It was concentrated on significant cerebellum and medulla oblongata. The cerebellum occupied the rostral part of dorsal wall of fourth ventricle. The fourth ventricle was visible on 1 day old and by aging was majorly. The fourth ventricle lied on the caudally and continued into central canal (cc) in spinal cord. Cortex of cerebellum had three layers, which were visible from 6 days old. Granular layer of corpus cerebelli, eminentia granularis, and less valvula cerebelli contained Golgi type II, and purkinje cells and observed from 6 days old clearly. Three sulci recognized in cerebellum on 15 days old. Medulla oblongata located at the caudal part of cerebellum and observed from 1 day old and contained eminentia granulares and crista cerebellares. Nucleuses of facial and vagal nerves were in ventral thick part of medulla oblongata. This structure, similar to cerebellum had columns of columnar cells in its gray matter. The white and gray matter, in hindbrain was visible on 1 and 3 days old, and from 6 days old the rate of white matter increased. Stereological results showed that there were significantly distinctive regional differences in the volume of different parts of hindbrain represented a correlation and was P

The effect of two feeding rates (0.5 and 1.5% of total body weight) was assessed on the growth of pectoral fin spines of captive juvenile great sturgeon, Huso huso, after second year of life. The fish received Oxytetracycline (OTC) twice in the first and second years of their lives under basic diet. During the 5‐month experimental period, juveniles (mean 1,187.4 g, 0.1 standard deviation [SD]), n = 50) were reared with two feeding rates under similar conditions in 10 fiberglass tanks (1.5 m³). The fish were fed manually with a commercial diet twice a day (35% Biomar, Nersac, France) throughout the experiment. The OTC marks were distinguished in all pectoral fin spine sections under ultraviolet light. The means of the first and second annular radii were 806.6 µm (27.2 SD) and 2,246.5 µm (50.2 SD), respectively. The marginal increment analysis beyond the second OTC mark revealed a significantly smaller marginal increment for low feeding rate treatment (143.9, 11.2 SD) as compared to the high feeding rate one (269.0, 14.6 SD). The results indicate the slower growth rate in the fish fed the low feeding treatments seen in the pectoral fin spine formation, which can be used as an indicator of recent feeding history in sturgeon juveniles. The best daily feeding rate for great sturgeon of 2,460 g was determined to be 1.5% body weight/day in this study.

The control region of mitochondrial DNA (mtDNA) in sturgeon contains one to seven tandem nucleotide repeats 78-83 bp in size. Some sturgeon species are homoplasmic by the D-loop size (Acipenser nudiventris, A. oxyrinchus, A. sturio), some are mildly heteroplasmic (A. fulvescens, Huso huso) and some are markedly heteroplasmic (A. brevirostrum, A. medirostris, A. mikadoi, A. naccarii, and A. transmontanus). This work presents a comparison of the D-loop sequences associated with the termination of mtDNA replication in fish and the conservative sequences determining the termination of replication (TAS) in these organisms. It is proposed that the D-loop heteroplasmy in sturgeon may be associated with variation in the number of tandem repeat sequences, which can form stable spatial structures during mtDNA replication. In most sturgeon species with pronounced heteroplasmy, the energy levels required for the folding of tandem repeats containing variable number of repeated units differ minimally.

The Hydro development started in the 1960s with building 3 major dams in the upstream section of the Sakarya River. During the 1980s the development of the floodplain sections of the river had its onset. Under these altered conditions Huso huso, Acipenser nudiventris , and Acipenser sturio disappeared from the river until the 1980s but Acipenser gueldenstaedtii, as well as Acipenser stellatus, were shown to still reproduce in the remaining section of the river by 2013. The construction of three additional HEPPs begun in the river section below Pamukova, blocking migration and cutting off major spawning sites. While fish passage facilities were included in the construction of the HEPPs since the 1980s, their design and location, as well as the maintenance rendered them completely dysfunctional. A survey was carried out in the remaining free flowing section of the lower river in 2014 to determine fish commun ity composition and water quality at 4 stations below Adasu HEPP. While a few A. gueldenstaedtii juveniles were observed in Sakarya River mouth close to the Black Sea, only one young-of-the- (YOY) ( A. stellatus ; W:25g; TL:28cm) was reported which was captured from the Lower Sakarya River.

—Data based on the results of published, unpublished, and questionable materials concerning the occurrence of anadromous sturgeons after damming of the Don River downstream and upstream of the Tsimlyansk hydroengineering complex are presented. Two peaks of approaches of spawners to the dam in the 1950s and 1980s were recorded. The first peak was related to the wild population that existed in these years; the second peak was a result of mass artificial propagation. At the first stage, the Russian sturgeon (Acipenser gueldenstaedtii Brandt et Ratzeburg, 1833) and the beluga sturgeon (Huso huso (Linnaeus, 1758)) prevailed downstream from the dam; at the second stage, only the Russian sturgeon was recorded. Since 1955, only 21 individuals of anadromous sturgeons have made it through the dam by a fish ladder. During the years 1952–1961, 1145 individuals were transported into the reservoir, including 218 ind. of beluga. Some individuals of beluga were transported later as well. There are data indicating the presence of juvenile beluga individuals that originated from natural spawning in the reservoir before the 1970s. The last known spawners of Russian sturgeon and stellate sturgeon (Acipenser stellatus Pallas, 1771) in the reservoir were recorded in the 1980s or 1990s. Solitary beluga individuals may occur nowadays. It is suggested that the youngest of the noted individuals belong to the generations of the early 1990s. It is concluded that the extremely innumerous landlocked form of the Azov beluga may still exist in the reservoir.

The hybrid sturgeon (Huso dauricus × Acipenser schrenckii) is an economically important species in China. With the increasing aquaculture of hybrid sturgeon, the bacterial diseases are a great concern of the industry. In this study, de novo sequencing was used to compare the difference in transcriptome in spleen of the infected and mock infected sturgeon with Aeromonas hydrophila. Among 187,244 unigenes obtained, 87,887 unigenes were annotated and 1,147 unigenes were associated with immune responses genes. Comparative expression analysis indicated that 2,723 differently expressed genes between the infected and mock-infected group were identified, including 1,420 up-regulated and 1,303 down-regulated genes. 283 differently expressed anti-bacterial immune related genes were scrutinized, including 168 up-regulated and 115 down-regulated genes. Ten of the differently expressed genes were further validated by qRT-PCR. In this study, toll like receptors (TLRs) pathway, NF-kappa B pathway, class A scavenger receptor pathway, phagocytosis pathway, mannose receptor pathway and complement pathway were shown to be up-regulated in Aeromonas hydrophila infected hybrid sturgeon. Additionally, 65,040 potential SSRs and 2,133,505 candidate SNPs were identified from the hybrid sturgeon spleen transcriptome. This study could provide an insight of host immune genes associated with bacterial infection in hybrid sturgeon.

The reintroduction of the extinct beluga sturgeon (Huso huso L.), an anadromous species with economic and traditional relevance, is a priority in next conservation strategies in Northern Italy. The EU-LIFE NATURA project aims to reintroduce the beluga sturgeon in the Po River basin through a captive breeding program. Critical requirements for the success of the program are river connectivity and knowledge of genetic diversity of the selected broodstocks to ensure self-sustainability of reintroduced populations. Here, the four broodstocks used for the reintroduction of beluga sturgeon have been genetically screened, genotyping 13 loci and sequencing mitochondrial DNA cytochrome b (Cyt b) gene and the entire mitochondrial DNA control region (D-Loop). The four broodstocks showed a medium-high level of nuclear genetic variability and the presence of two sub-populations, evidencing a total level of inbreeding coefficients able to sustain the good potential as future breeders. Mitochondrial analyses showed a genetic variability comparable to wild populations, further strengthening the positive potential of the investigated broodstock. Therefore, this study, showed how the degree of genetic diversity found within the four broodstocks used for H. huso reintroduction in the Po River basin could be suitable to ensure the success of the program, avoiding the inbreeding depression associated with founder effect and captive breeding.

The present study investigated the effect of apsozyme and betaine on growth performance, carcass composition, haemato-immunological parameters, and expression of growth hormone (GH) and insulin-like growth factor 1 (IGF1) encoding genes in beluga sturgeon (Huso huso). Fish (31.5 ± 0.5 g) were fed with different levels of multi-enzyme (i.e., 0, 250, and 500 mg) and attractant (i.e., 0.5%, 1.0%, and 1.5%). The results obtained from this study indicated that no significant difference was detected in weight gain, specific growth rate (SGR), feed conversion ratio (FCR), and growth-related genes expression with an increase in betaine in experimental treatments (P > 0.05). However, an increase in apsozyme from 250 mg to 500 mg without betaine resulted in significant elevations in weight gain, SGR, FCR, and growth-related gene expression (P 0.05). Also, the blood biochemical factors including glucose, and hepatic enzymes, i.e., alkaline phosphatase (ALP), alanine aminotransferase (ALT), and aspartate aminotransferase (AST), were not found significantly different (P > 0.05), whereas significant increases were observed in protein, albumin, and lysozyme with increased apsozyme in the diet in combined treatments (P

Sturgeon is one of the ancient fish species with the fossil records over 200 million years ago. However, the sturgeon genomes are rather complicated, owing to several rounds of genome polyploidizations, which makes it difficult to assemble a high quality genome so that only a few studies analyze their whole genome evolutions (WGDs). This study applied the PacBio sequencing technology to sequence the full-length transcriptomes of blood samples of octoploid Huso dauricus, octoploid Acipenser schrenckii and tetraploid Acipenser stellatus. A total of non-redundant 33,407 transcript assemblies of the three sturgeons were finally generated and fully annotated with different gene function databases, as well as the predictions of simple sequence repeats, transcription factors and long non-coding RNAs. Data valuation exhibited that annotations of the three transcriptomes had the higher quality than those of the previously sequenced sturgeon genomes. A phylogeny of eight typical sturgeons was constructed using the low copy genes, which illustrated that Acipenser and Huso might share a single origin. The sturgeon WGDs were parallelly timed by calculating the divergence times of 2-member gene clusters and heterozygous-SNP-carried genes, which both suggested the occurrence of the WGDs later than 150 mya. The full-length transcriptome sequences were supposed to be the reliable reference data for the study of sturgeon.

In this study, six candidate female-specific DNA sequences of octaploid Amur sturgeon (Acipenser schrenckii) were identified using comparative genomic approaches with high-throughput sequencing data. Their specificity was confirmed by traditional PCR. Two of these sex-specific sequences were also validated as female-specific in other eight sturgeon species and two hybrid sturgeons. The identified female-specific DNA fragments suggest that the family Acipenseridae has a ZZ/ZW sex-determining system. However, one of the two DNA sequences has been deleted in some sturgeons such as Sterlet sturgeon (Acipenser ruthenus), Beluga (Huso huso) and Kaluga (H. dauricus). The difference of sex-specific sequences among sturgeons indicates that there are different sex-specific regions among species of sturgeon. This study not only provided the sex-specific DNA sequences for management, conservation and studies of sex-determination mechanisms in sturgeons, but also confirmed the capability of the workflow to identify sex-specific DNA sequences in the polyploid species with complex genomes.

In this study, we isolated and characterized natural antibodies found in serum samples from Bester sturgeon (Huso huso × Acipenser ruthenus). Natural antibodies specifically detected hen egg lysozyme (HEL), keyhole limpet hemocyanin (KLH), and several species of pathogenic bacteria. Interestingly, we detected no antibodies with similar specificity in serum samples from rainbow trout (Oncorhynchus mykiss) or from Japanese flounder (Paralichthys olivaceus). Binding capacity of the sturgeon natural serum antibodies increased slightly at 7 months compared to 3 months after hatching. Antigen-specific antibodies against KLH, Aeromonas hydrophila and Streptococcus iniae were affinity-fractionated from naive sera of Bester sturgeon; specific detection of the corresponding antigens was observed. We conclude that Bester sturgeon are capable of generating unique natural antibodies including those that are pathogen-specific.

The article presents data on the cultivation of Beluga stocking material, studies of the size indicators of embryos and morphometric indicators of Beluga larvae at different stages of development, analyzes of piscicultural- biological and hematological indicators. It was found that the Beluga juveniles reached the weight corresponding to the enlarged ones of sturgeon taking as standard at this enterprise. The survival rate was slightly higher than the norm.

International audience; GnRH is a neuropeptide known to regulate reproduction in vertebrates. The purpose of this study was to design and produce recombinant gonadotropin-releasing hormone associated peptide (rGnRH/GAP) as an alternative of the previous GnRHs and native extracted hormone from tissue, to induce final maturation in fish. Decapeptide as well as GAP area sequences were compared between GnRH1, GnRH2, and mGnRH from Acipenser sp and Huso huso, respectively. Considering the conserved amino acids and the replacement of un-stable amino acids with those that were more stable against proteolytic digestion as well as had a longer half-life, the sequence was designed. The sequences of decapeptide and GAP region were synthesized and then cloned on pET28a expression vector and transformed into expression host Escherichia coli BL21(DE3). The supernatant of cultured recombinant bacteria was used for purification using TALON Metal affinity resin. The purity of the GnRH/GAP was confirmed by single 8 kDa band on SDS-PAGE and Western blot. Bioinformatics studies were performed for evaluation of homology between GnRH protein sequences and prediction of 3D protein structure using Swiss Model. The result showed that the structure prediction of the recombinant GnRH decapeptide was relatively similar to decapeptide of GnRH2 from Beluga (Huso huso). The GAP structure was similar to GAP1 of Nile tilapia (Oreochromis niloticus) and sturgeon and GnRH2 of Chinese sturgeon (Acipenser sinensis). The mass analysis showed that the sequence was exactly the same as designated sequence. Biology activity of rGnRH/GAP was tested in mature goldfish (Carassius auratus) and results showed that rGnRH/GAP had a positive effect in final maturation. Indeed 17α, 20β-dihydroxy-4-pregnen-3-one (DHP) was increased 17 h and 24 h after injection with rGnRH/GAP and spawning stemmed from that injection. These novel findings introduce the potential of utilizing rGnRH/GAP in aquaculture.