Russian Sturgeon Research Articles

ВЛИЯНИЕ СКОРОСТИ ЗАМОРАЖИВАНИЯ НА РЫБОВОДНЫЕ КАЧЕСТВА СПЕРМЫ ОСЕТРОВЫХ РЫБ

The article describes the methods of cryopreservation which provides the reliable protection of cell organelles integrity after freezing-defrosting processes, as well as the needed supply of organic substances generating metabolic process in cells and tissues after a double temperature shock, and helps to achieve a significant progress in the cell long-term storage. There are considered the aspects of low temperature preservation of sturgeon sperm. Reproductive cells of Russian sturgeon ( Acipenser gueldenstaedtii Brandt & Ratzeburg, 1833) and sterlet ( Acipenser ruthenus Linnaeus, 1758) obtained at sturgeon hatcheries of the Astrakhan region and the research-expeditionary base “Kagalnik” in the Rostov region during spawning campaign served as the material for research. The purpose of the work was to establish optimal freezing rates during sturgeon sperm cryopreservation process that could ensure saving structural components of reproductive cells. It has been found that the freezing rate is species-specific. The best freezing speed for Russian sturgeon sperm proved to be 3°C/min. When experimenting with sterlet sperm there was registered less damage after freezing and defrosting at 10°C/min. Freezing speed 3°C/min was found less effective for sterlet sperm. Staged freezing process showed worse results in both cases. However, the quality of defrosted sperm didn’t get lower the fish breeding standards in all three studied speeds, which justifies sturgeon sperm freezing at all three rates subject to different conditions of preservation.

Optimization of In Vitro Culture Conditions of Sturgeon Germ Cells for Purpose of Surrogate Production.

Simple SummaryThe sturgeon is among the most ancient of actinopterygian fishes. Most species of sturgeon are listed as critically endangered due to habitat alteration caused by damming of rivers, pollution and overharvesting. Germ cell transplant is a useful tool to save these endangered species. To expand germ cell populations and sustain the supply for long periods for transplant, we established basal culture conditions for sturgeon germ cells. Germ cell mitotic activity has been enhanced by eliminating gonad somatic cells, supplementing with growth factor and using an alternative to fetal bovine serum. The optimal condition identified was purified germ cells cultured in serum-free medium supplemented with leukemia inhibitory factor (LIF) and glial cell line-derived neurotrophic factor (GDNF) at 21 °C. Cultured sterlet germ cells showed development after transplant into Russian sturgeon. The study provided useful information for sturgeon germ cell culture.To expand germ cell populations and provide a consistent supply for transplantation, we established basal culture conditions for sturgeon germ cells and subsequently increased their mitotic activity by eliminating gonad somatic cells, supplementing with growth factor, and replacing fetal bovine serum (FBS). The initial basal culture conditions were Leibovitz’s L-15 medium (pH 8.0) supplemented with 5% FBS (p < 0.001) at 21 °C. Proliferation of germ cells was significantly enhanced and maintained for longer periods by elimination of gonad somatic cells and culture under feeder-cell free conditions, with addition of leukemia inhibitory factor and glial-cell-derived neurotrophic factor (p < 0.001). A serum-free culture medium improved germ cell proliferation compared to the L-15 with FBS (p < 0.05). Morphology remained similar to that of fresh germ cells for at least 40 d culture. Germline-specific gene expression analysis revealed no significant changes to germ cells before and after culture. Sterlet Acipenser ruthenus germ cells cultured more than 40 days showed development after transplant into Russian sturgeon Acipenser gueldenstaedtii. Polymerase chain reaction showed 33.3% of recipient gonads to contain sterlet cells after four months. This study developed optimal culture condition for sturgeon germ cells. Germ cells after 40 d culture developed in recipient gonads. This study provided useful information for culture of sturgeon germ cells.

Comparative transcriptome analysis reveals expression signatures of albino Russian sturgeon, Acipenseriformes gueldenstaedtii

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.

Influence of interspecific hybridization on fitness-related traits in Siberian sturgeon and Russian sturgeon

Polyploidy in sturgeons makes them highly susceptible to interspecific hybridization, and these interspecific hybrids have been described in nature as well as in captivity. Nevertheless, the fitness-related traits between sturgeon hybrids and pure species have been poorly compared as yet. In the present study, we compared the reproductive parameters such as fertilization rate and hatching rate, growth traits and genetic polymorphism in the artificially produced hybrids of the Siberian sturgeon (Acipenser baerii) and Russian sturgeon (A. gueldenstaedtii) with their purebreds. Fertilization and hatching rates were found to be significantly higher in Siberian sturgeon (♀) × Russian sturgeon (♂) hybrid group compared to purebreds. The highest cumulative survival rate was determined in purebred groups until 151 days post-hatch (dph); however, this trend changed and Russian sturgeon purebred showed the lowest cumulative survival rate (0.21%) by 913 dph. Similarly, the lowest average body weight was recorded in Russian sturgeon purebred group (264 g). In contrast, the highest average body weight was recorded in Russian sturgeon (♀) × Siberian sturgeon (♂) hybrids (435.3 g) and the highest cumulative survival rate was recorded in Siberian sturgeon (♀) × Russian sturgeon (♂) hybrids (12.32%) by 913 dph. No significant differences were found at heterozygosity levels among studied crosses. Our results showed that studied sturgeon hybrids had higher survival and growth if compared with the purebreds under provided hatchery conditions.

Sturgeon meat and caviar production: Global update 2017

This paper presents an update on the global sturgeon and caviar production until 2017, attempting to continue previous efforts on summarizing the global trends in these markets. For the current update, an expanded data base was derived from questionnaires sent to 86 regional contacts in 46 countries, mostly farmers or scientists, and personal interviews. A total of 2,329 commercial sturgeon farms were recorded by 2017 globally, which represented an increase by 7% compared to 2016. Of these farms 54% were located in China, followed by Russia (24%), the Middle East (8%), the Far East (7%) and Europe (6%). Among the rearing technologies flow-through (FT) systems (36%) were most common, followed by recirculation aquaculture systems (RAS) (21%), cages (18%), mix FT/RAS (11%), and ponds (6%). In total the aquaculture sturgeon biomass production peaked at about 129,608 t in the year 2015, with a decline to 119,979 t in 2016, and to 102,327 t in 2017. China contributed about 79,638 t to the overall production in 2017, followed by Russia (6,800 t), Armenia (6,000 t), Iran (2,514 t), and 52 other countries with less than 1,000 t each. This production exceeded the fishery harvest during the 1970–1980s by more than four times. Of the 25 species of Acipenseridae, 13 pure species and four hybrids were farmed for meat with Acipenser baerii dominating production in 2016 with a share of 39.5%, followed by the two hybrids, Huso dauricus × Acipenser schrenckii and A. baerii × A. schrenckii (35.6%), as well as A. schrenckii (10.2%). Global caviar production increased during the last years and the production for the year 2017 amounted to approximately 364 t. China contributed more than 100 t to the overall production in 2017, followed by Russia (49 t), Italy (43 t), France (37 t) and diverse other countries. The species composition in caviar production in 2016 was dominated by A. baerii (31% of the total volume), followed by Acipenser gueldenstaedtii (20%), the hybrid H. dauricus × A. schrenckii (13%), and Acipenser transmontanus (12%), while other species jointly contributed 24% to the overall yield. The trends of sturgeon meat and caviar productions of the last 5 years and the forecasts for the future suggest a short-term scenario in which the demand remains lower than the supply. In order to absorb the growing production, the market will have to be expanded by targeting new market segments.

Factors influencing the natural reproduction decline in the beluga ( Huso huso , Linnaeus, 1758), Russian sturgeon ( Acipenser gueldenstaedtii, Brandt &amp; Ratzeburg, 1833), and stellate sturgeon ( A. stellatus , Pallas, 1771) of the Volga–Caspian basin: A review

The review describes the changes in natural reproduction of three important sturgeon species in the Volga–Caspian basin: (a) the beluga (Huso huso Linneaus, 1758), (b) the Russian sturgeon (Acipenser gueldenstaedtii Brandt &Ratzeburg, 1833), and (c) the stellate sturgeon (Acipenser stellatus Pallas, 1771). Since the past 60 years, these species responded to severe influences of natural and anthropogenic factors. On the basis of original and published data, an analysis has been made of (a) the numbers of larvae migrating from spawning sites (according to plankton net survey), (b) fecundity and histological anomalies in gonad development, (c) the numbers of adult sturgeons in the Caspian Sea and of spawners migrating to the Volga River (according to trawl and beach seine survey), and (d) foraging resources for the sturgeons. The results show that their natural reproduction in the Volga–Caspian basin has declined drastically during the past decades under the impact of (a) fluctuations of the Caspian Sea level and flow discharge from the Volga River, (b) blockage of sturgeon migration routes and loss of spawning sites because of dam construction, (c) water pollution in the lower reaches of the Volga River and in the Caspian Sea, and (d) intensive and selective illegal and unreported fishing. The relative significance of these factors has been changing during the study period.

Ontogenetic behavior of farm-bred Russian sturgeon (Acipenser gueldenstaedtii) prelarvae in a diel photoperiodic cycle: behavioral modifications in response to light intensity

Russian sturgeon (Acipenser gueldenstaedtii) is commercially important in Korea because its caviar is highly prized. Although the early ontogeny of the species has been described, behavioral modifications in response to various light intensities or diel photoperiodicity patterns have not been studied extensively. The objective of the present study was to examine the behavioral characteristics of hatchery-produced A. gueldenstaedtii prelarvae over a diel photoperiodic cycle. During a diel light cycle comprising 16 h of daylight (450 lx), 4 h of dim light (10 lx), and 4 h of darkness (< 1 lx), newly hatched A. gueldenstaedtii prelarvae exhibited negative phototaxis in daylight (day 0–day 2), and this early behavior was not significantly affected by changes of light intensities. Rheotactic and non-rheotactic aggregation into schools was typical between days 3 and 6. Under the diel light cycle conditions described, rheotaxis was not influenced by environmental light intensity as much as non-rheotactic schooling behavior. Post-schooling behavior, which progressed from day 7 to day 8, did not change significantly during the diel light cycle. The data from the present study could be of practical value in developing a visual guide for assessing the fitness and quality of Russian sturgeon prelarvae under diel light cycle conditions in hatcheries.

Genetic monitoring of natural sturgeon spawning in the lower Volga for the period 2017-2018

Genetic monitoring of natural sturgeon spawning in the lower Volga for the period 2017-2018

Ontogenetic Behavior and Phototactic Properties of Interspecific Hybrid Prolarvae Produced by Crossing Female Siberian Sturgeon Acipenser baerii and Male Russian Sturgeon Acipenser gueldenstaedtii

Ontogenetic Behavior and Phototactic Properties of Interspecific Hybrid Prolarvae Produced by Crossing Female Siberian Sturgeon Acipenser baerii and Male Russian Sturgeon Acipenser gueldenstaedtii

PRESENT STATUS OF STURGEON IN THE LOWER SAKARYA RIVER IN TURKEY

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.

Оценка численности сеголеток русского осетра в северо-западной части Каспийского моря

Оценка численности сеголеток русского осетра в северо-западной части Каспийского моря

Порог ощущения природных аминокислот у рыб

On the example of the naive juvenile of the Russian sturgeon, thresholds of sensation (detection) of amino acids and their derivatives in fish are determined. There is a relationship between the thresholds of sensation of amino acids and their physico-chemical properties. Of the nine test amino acids, the minimum thresholds of sensation in fish are established for histidine, methionine, and tyrosine.

Analysis of the influence of ecological parameters on the results of growing fry of russian sturgeon in ponds

Analysis of the influence of ecological parameters on the results of growing fry of russian sturgeon in ponds

First review of recent records of sturgeons and paddlefishes (Acipenseriformes) in the Danube River basin in Slovenia

We present recent records of sturgeons and paddlefishes from the rivers in Danube basin in Slovenia after 2000. Strictly, only confirmed and unambiguous records (specimen, picture) were taken into account. The sterlet and the Siberian sturgeon have been occasionally found in rivers and Russian sturgeons in gravel pits, while sterlets, Siberian sturgeons, Russian sturgeons and the paddlefish are still farmed in some ponds. The Siberian sturgeons were released in the Mura and Sava River in 2016, but the species is as »exotic pet fish« present in more water bodies. The presence of sturgeons in gravel pits is unknown. The Siberian sturgeon can be relatively easily misidentified with the sterlet, so the catches in the Mura and Sora Rivers in 2009 were misidentified as sterlet, while the Siberian sturgeon was actually captured. The last sterlet in Slovenian rivers was captured in the Drava River in 2001, and even this individual had probably been released in Austria. The occurrence of sturgeons in Slovenian rivers in the last eighteen years does not seem to be connected with migration and revival of natural populations in the lower part of the Drava and Sava Rivers.

Growth Performance, Body Composition, Haematological and Serum Parameters to Fish Meal Replacement by Soybean Meal and Cottonseed Meal in Russian Sturgeon (Acipenser gueldenstaedtii)

In this study, the effects of replacement of fish meal by soybean meal and cottonseed meal on growth, body composition, blood and serum parameters of Russian sturgeon (Acipenser gueldenstaedtii) were investigated. Five experimental diets were formulated to be isonitrogenous (49 % protein) and isolipidic (20 % lipid). Diets were prepared with graded levels (20 % and 40 %) of soybean (SM) and cottonseed (CM) meals as SM20, SM40, CM20, CM40 and a control diet (FM, only fish meal with no SM and CM inclusion). Sturgeon (50.00±0.06 g) were randomly distributed into fifteen 500-L square tanks at 25 fish per tank. Fish were weighed in bulk biweekly after suspending feeding for 1 day. Fish were fed near satiation by hand at 08:00, 12:00 and 16:00 hours for 8 weeks. Sturgeon fed CM20 and CM40 diets displayed higher specific growth rate (SGR) and lower feed conversion ratio (FCR) when compared with fish fed SM40 and FM (P&amp;lt;0.05). There were no differences among groups for the percentage of blood cells, including lymphocytes, monocytes and granulocytes of sturgeons. Alkaline phosphatase (ALP) of SM20 and SM40 groups were significantly lower than that of FM group (P&amp;lt;0.05). The results of this study revealed that dietary cottonseed meal could be used for enhancement in juvenile sturgeon.

Genetic identification of two Acipenser iridovirus-European variants using high-resolution melting analysis

Acipenser iridovirus-European (AcIV-E) is an important pathogen of sturgeons. Two variants differing by single-nucleotide polymorphisms (SNP) in the Major Capsid Protein gene have been described, but without any indication as to their prevalence in farms. To facilitate epidemiological studies, we developed a high-resolution melting (HRM) assay to distinguish between two alleles (var1 and var2) differing by five point substitutions. The HRM assay detected as little as 100 copies of plasmids harboring cloned sequences of var1 and var2, which have melting temperatures (Tm) differing by only 1 °C. The assay was specific of AcIV-E as demonstrated by the absence of signal when testing a related, yet distinct, virus as well as DNA from an AcIV-E-negative sturgeon sample. Experiments with mixtures of two distinct plasmids revealed abnormal melting curve patterns, which showed dips just before the main melting peaks. These dips in the curves were interpreted as the dissociation of heteroduplexes fortuitously created during the PCR step. Screening AciV-E-positive field samples of Russian sturgeons from three farms revealed the presence of var2, based on the Tm. However, for a few samples, the melting curves showed patterns typical of var2 as the dominant viral genome, mixed with another minor variant which proved to be var1. In conclusion, HRM is a simple method to screen for AcIV-E var1 and var2 and can be used on a large scale in Europe to trace these two variants which likely represent two genetic lineages.

Sex-related gonadal gene expression differences in the Russian sturgeon (Acipenser gueldenstaedtii) grown in stable aquaculture conditions

The Russian sturgeon (Acipenser gueldenstaedtii) is a primitive freshwater fish and a source of caviar. In the present study, the gonadal transcriptomes of male and female Russian sturgeons grown in stable aquaculture conditions were analyzed. RNA sequencing of whole-gonad transcriptomes from pools of 4-year old fish (five females, four males), resulted in the identification of 28,170 unique transcripts. Of these, 16,191 could be annotated by similarity to gene sequences from other species. There were 392 transcripts that showed differential abundance by a factor of 20-fold or more between the sexes; 272 of these were annotated; of these, 175 and 97 were in greater abundance in ovaries and testes, respectively. Functional annotation and clustering of the genes with differential abundances of mRNA allowed for identification of several clusters. Thus, a group of transcriptional regulators and factors involved in cell division, especially septins, were in greater abundance in the ovaries; while a different set of transcription factors (including sox6 and sox30) and a group of protein kinases were in greater abundance in the testes. The transcript abundances of nine highly abundant candidate transcripts, as well as of two additional genes previously known to be involved in reproduction, cyp19 (p450 aromatase) and foxl2, were assessed in the individual samples by qRT-PCR. Of these, five (including cyp19 and foxl2) were in greater abundance in ovaries, while the abundance of ighm1 mRNA was greater in testes. Phylogenetic analysis based on the k1c18 keratin gene placed the sturgeon sequence nearest those of other primitive fish species, supporting the ancient origin of the sturgeon. In conclusion, this study details transcriptome differences between male and female sturgeon and identifies key genes that may contribute to sexual determination and differentiation.

Anadromous Sturgeons (Acipenseridae, Actinopterygii) of the Don River Upstream from the Tsimlyansk Hydroengineering Complex

Abstract—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.

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

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

A new marker, isolated by ddRAD sequencing, detects Siberian and Russian sturgeon in hybrids.

A new marker, isolated by ddRAD sequencing, detects Siberian and Russian sturgeon in hybrids.