Amur Sturgeon Research Articles

Enteritis in hybrid sturgeon (Acipenser schrenckii♂ × Acipenser baeri♀) caused by intestinal microbiota disorder

Intestinal microbiota is crucial for the regulation of the immune system and feeding habits in aquatic animals, as well as preventing the invasion of pathogenic microorganisms. However, disorders of the intestinal microbiota can lead to numerous, possibly life-threatening diseases. In the present study, we reported a disease occurring in cultured hybrid sturgeons (Acipenser schrenckii♂×Acipenser baeri♀) in the Sichuan province, Southwest China. The diseased fish did not exhibit obvious skin lesions, with observed symptoms including intestine dilatation with large amounts of gas and a transparent intestinal wall. Pathological examinations, microbiological tests, and the high-throughput sequencing of intestinal microbiota were performed to investigate the cause of death of diseased sturgeons. Results demonstrated that no bacteria were isolated from the liver, spleen and kidney, and no obvious changes were observed in tissues, with the exception of the intestine. The intestines demonstrated marked necrotic enteritis with lumen dilatation and a large number of bacteria attached to the base of the intestinal villus. Furthermore, observations from an electron microscope revealed the invasion by bacteria of the striated border. Results from the 16 s rRNA high-throughput sequencing of intestinal microbiota indicate variations in the relative abundance and distribution uniformity of the intestinal microbiota in the diseased group. More specifically, the intestinal microbiota abundance in the diseased group was higher in Clostridium, Cetobacterium, and Lactococcus, and lower in Mycoplasma at the genus level compared to the healthy group. Our observations suggest that the death of the hybrid sturgeons was caused by intestinal enteritis, which itself was a result of the intestinal microbiota disorder. To our knowledge, this is the first study to reveal hybrid sturgeon death via enteritis caused by an intestinal microbiota disorder.

Structural characterization and proliferation activity of chondroitin sulfate from the sturgeon, Acipenser schrenckii

The cartilages of marine fish, such as sharks and sturgeon, are important resources of the bioactive chondroitin sulfate (CS). To explore glycosaminoglycans from marine fish, polysaccharides from the cartilage of the sturgeon, Acipenser schrenckii, were extracted. Using enzyme-assisted extraction and anion-exchange chromatography, an uronic acid-containing polysaccharide, YG-1, was isolated. YG-1 is composed of GlcN, GlcUA, GalN, and Gal, in the ratio of 1.4: 3.4: 3.7: 1.0, and its molecular weight was determined to be 3.0 × 105 Da. YG-1 was confirmed to be chondroitin 4-sulfate (CS) composed of →4GlcAβ1→3GalNAc4Sβ1→ and minor →4GlcAβ1→3GalNAcβ1→, which was confirmed using IR spectroscopy, disaccharide composition analysis, and NMR. Bioactivity studies, including MTT assay and scratch-wound assays revealed that CS from Acipenser schrenckii had significant proliferation activity. The proliferation activity of the polysaccharide, YG-1, was related to Fibroblast growth factor 2 (FGF2). GalNAc 4S of YG-1 could be the binding sites of FGF2 and FGFR.

Plant protein diet-induced hypoimmunity by affecting the spiral valve intestinal microbiota and bile acid enterohepatic circulation in Amur sturgeon (Acipenser schrenckii)

An 8-week growth trial was conducted to study enterohepatic recirculation of bile acid metabolism and the intestinal microbiota of Amur sturgeon (Acipenser schrenckii) fed with three diets, including 540 g/kg, 270 g/kg or 0 g/kg fishmeal, which was correspondingly replaced by a plant protein blend (named P0, P50 and P100, respectively). The diets were designed to be isonitrogenous, isoenergetic and essential nutrients balanced. With rising levels of dietary plant protein, disruption of the spiral valve intestinal microbiota and more morbidity with liver disease were observed in the P100 group, although there were no haematological abnormalities observed. An obvious bile acids enterohepatic circulation disorder was found with phenotypes of increased liver bile acids compensatory synthesis, and reduced expression of bile acid receptors (FXR and TGR5), which induced BA accumulative toxicity. Accompanied by increased oxidative stress, it further induced hepatic lesions and hypoimmunity, which were non-negligible reasons for the high mortality and low utilization ability of plant protein by Amur sturgeon.

Growing a triple hybrid of russian, siberian and amur sturgeons in a warm-water fish farm

Biological and production indices are presented for spawning females of triple hybrid between russian sturgeon, siberian sturgeon and amur sturgeon (RS × SS) × AS and other commercial forms of sturgeon grown in cages of the warm-water fish farm in Luchegorsk, Far East of Russia. In conditions of warm-water pools, survival rate of the triple hybrid larvae and juveniles was higher than that of amur sturgeon and russian-siberian hybrid sturgeon. Weight of the triple hybrid specimens at the age of 3 and 4 years was 1.58 kg and 2.36 kg, respectively, that was higher than that of the russian-siberian hybrid sturgeon and close to the values for amur sturgeon. Fish harvest reached 94 kg/m2 of cage, or 134 kg/m2 of cage in sum with the realized fish. Up to 93 % of females matured after using of hormonal stimulation. The first female of the triple hybrid sturgeon matured at the age of 9 years, with its body weight of 13.1 kg. Other females became matured in different age, up to 16 years, but ¾ of them were matured at the age of 10–12 years. The maximum registered weight of the triple hybrid female was 29 kg (age 14 years). Inter-spawning intervals for 97 % of females were 1–2 years. Average annual yield of hard roe obtained from one female at the age of 9–16 years was 2.28 kg, average weight of one egg was 17.6 mg, average fecundity was 132 . 103 eggs/female or 7.4 . 103 eggs/kg, average oosomatic index was 12.8 %. These values of production indices for the triple hybrid females are mainly intermediate between the indices of initial species. In 3–4 spawning seasons, the yield of 5.25 kg of hard roe, on average, was harvested from one female of the triple hybrid, or 30 % of its body weight. The yield from the most productive females was 10.8–11.0 kg of roe, or 55–73 % of their body weight. These values are lower than the yeild from amur sturgeon but similar to the yield value for russian-siberian hybrid sturgeon. Caviar manufactured from the roe of triple hybrid sturgeon is distinguished by high quality. Its females are technologically advanced for the eggs harvesting and have a good survival, about 98 % during long-term exploitation. So, the triple hybrid of russian, siberian and amur sturgeon can be recommended for commercial cultivation in warm-water sturgeon farms with intensive harvesting.

Species composition and distribution of fishes and prawns in the Amur River channel

istribution of fishes and prawns in the Amur River (40–960 km from the mouth) is described on results of the beam-trawl survey conducted in September-October, 2003 (57 trawl stations at the depth of 1.5–23.0 m). In total, 2584 ind. of 22 fish species and 1077 ind. of 1 invertebrate species (prawn Palaemon modestus) were caught. The highest species richness was registered for orders Cypriniformes (13 species) and Siluriformes (4 species). The fish and prawn stocks were evaluated as 32.161 . 106 ind. (583.8 t) for bottom and near-bottom fish and 4.887 . 106 ind. (8.8 t) for prawns. Two commercial fish species were the most abundant: catfishes Tachysurus brashnikowi (16.26 . 106 ind. or 32.9 % of total biomass) and T. sinensis (4.32 . 106 ind. or 24.0 % of total biomass); other 6 fish species with considerable biomass were lizard gudgeon Saurogobio dabryi (12.6 %), ussuri catfish T. ussuriensis (9.7 %), amur white-pinned gudgeon Romanogobio tenuicorpus (7.8 %), amur sturgeon Acipenser schrenckii (5.6 %), amur gudgeon Gobio cynocephalus (2.4 %), and kaluga Huso dauricus (0.6 %). Distribution density varied in the range of 0.01–2.57 g/m2 (on average 0.45 ± 0.27 g/m2) for fish and 0.005–0.044 g/m2 (0.021 ± 0.012 g/m2) for prawns. Abundance of both fish and prawns increased multifold towards the Amur mouth that correlated with increasing of forage benthos biomass in the same direction. So, the main portion of fish biomass (82.4 %) was distributed in the Amur River downstream (40–400 km from the mouth) and the prawn stock was concentrated completely in its lowermost part (50–150 km from the mouth).

Asymmetric Hybridization of Kaluga Acipenser dauricus Georgi, 1775 and Amur Sturgeon A. schrenckii Brandt, 1869 (Acipenseridae) in Nature as Follows from Analysis of Mitochondrial and Nuclear DNA Markers

Natural hybridization of sturgeon species in sympatry area is a relatively frequent but poorly studied phenomenon. A unique picture of asymmetric hybridization for Acipenseridae has developed in the Amur River, the place of inhabitation of two endemic sturgeons of this river basin—Kaluga and Amur sturgeon. Earlier, we showed that the fraction of their hybrids in different years was about 2.5% of the abundance of parent species. All analyzed hybrids carried only one type of mtDNA—Kaluga. However, the identification of hybrids and pure individuals in this study was based on consideration of only external morphological characteristics. In the present work, the set of genetic markers was expanded to include six nuclear loci in the analysis: two introns of the ribosomal protein L8 (RP4L8, RP5L8) and microsatellites An20, Afug41, HLJSX37, and HLJSX350. As a result, it was shown that all morphologically intermediate individuals, previously classified on this basis as hybrids, for each of the nuclear loci had a mixed composition of alleles characteristic of both Kaluga and Amur sturgeon. Among those individuals which by external morphology were identified by collectors as Kaluga, there were identified three individuals that should be classified as hybrids according to their genetic characteristics. In addition, four other individuals were classified as backcrosses to Kaluga. All hybrids and backcrosses had Kaluga mtDNA type, which confirms the earlier conclusion about unidirectional hybridization of Kaluga and Amur sturgeon in nature: Kaluga (♀) × Amur sturgeon (♂). The used set of markers has the necessary resolution and can be recommended for the identification of pure Kaluga and Amur sturgeon and their hybrids. The minimum set of markers for diagnosis includes mtDNA, introns RP4L8 and RP5L8, and microsatellite HLJSX37.

Use of a paraprobiotic and postbiotic feed supplement (HWF™) improves the growth performance, composition and function of gut microbiota in hybrid sturgeon (Acipenser baerii x Acipenser schrenckii)

The contribution of cold water aquaculture for the world fish production is significant. Although sturgeon farming is an important part of China's cold water aquaculture industry, its production is less compared with the current potentiality of the country. There are many reasons for the lower production of cold water fish farming including feed and disease. The aim of the present study was to investigate the effect of a paraprobiotic and postbiotic feed supplement (Herpes Worry Free or HWF™) on the growth, feeding efficiency and gut microbiota balance of hybrid sturgeon. Besides, the effect of sturgeon gut microbiota fed on the diet supplemented with HWF™ on the expression of growth promoter, and immune regulatory genes of germ free (GF) zebrafish was evaluated. Sturgeon were fed for three weeks with HWF™ supplemented or basal diet. At the end of the experiment gut content of sturgeon, fed on either experimental diet was transferred and colonized to GF zebrafish. Sturgeon fed with HWF™ supplemented diet showed significantly higher weight gain rate and lower feed conversion ratio (FCR) as compared with the control (P < 0.05). Compared with the control group, the relative abundance of Firmicutes, were significantly higher in the HWF™ group (P < 0.05), whereas Proteobacteria, Actinobacteria and Chlamydiae were significantly higher in the control group (P < 0.05). Furthermore, at the genus level Clostridium (64.50 ± 5.99%) and Lactococcus (29.5 ± 3.05%) were the most dominant gut bacteria in the HWF™ group and the control group of sturgeon, respectively. The expression of genes related to growth, inflammation and non-specific immunity was significantly upregulated in GF zebrafish colonized with gut microbiota of HWF™ sturgeon group. In conclusion, HWF™ played significant role in growth, feed efficiency and modulation of gut microbiota of sturgeon. The gut microbiota of sturgeon fed on the diet supplemented with HWF™ upregulated the expression of genes related to growth, inflammation and non-specific immunity in GF zebrafish model.

Seasonal variation in diet of juvenile Amur sturgeon Acipenser schrenckii in the lower reaches of the Songhua River, Northeast China

We investigated seasonal variation in the diet of hatchery-reared juvenile Amur sturgeon Acipenser schrenckii in the Tongjiang reach of the Songhua River, Northeast China. The results indicated that Amur sturgeon fed mainly on Chironomidae and Ephemeroptera and secondarily on unspecified bony fish, Odonata, and Trichoptera. Diet changed throughout the year, with autumn 2017 and spring 2018 dominated by Ephemeroptera larvae, while summer 2018 prey comprised primarily Chironomidae larvae. Unspecified bony fish were observed at greater frequency in autumn 2017. Amur sturgeon captured in summer contained a greater quantity of Trichoptera larvae compared to those from autumn and spring sampling. Results were consistent with previous reports of Amur sturgeon diet in other areas of its native distribution and suggested that they may be opportunistic feeders throughout the year, although larval Chironomidae and Ephemeroptera appear to be important prey. These results represent the first reported diet composition data for juvenile Amur sturgeon in the lower Songhua River. Results of the study form part of a comprehensive investigation of feeding habits of juvenile Amur sturgeon that provides basic data for study of the biological characteristics of the species.

Dietary SWF® enhanced growth performance and disease resistance in hybrid sturgeon (Acipenser baerii x Acipenser schrenckii) mediated by the gut microbiota

The presence of healthy gut microbiota in the gastrointestinal tract of fish is important for the optimal function of gut, which plays a significant role in the host growth and health. The aim of the present study was to investigate the effect of dietary stress worry free (SWF®) on growth, feed utilization and disease resistance of hybrid sturgeon (Acipenser baerii x Acipenser schrenckii). Sturgeon were fed for three weeks with SWF® supplemented or basal diet. The weight gain and FCR of sturgeon fed on the diet supplemented with SWF® were significantly improved (P<0.05). SWF® supplemented diet provoked an increase in the resistance of sturgeon against A. veronii Hm091 (P=0.09). In terms of gut microbiota, the number of total bacteria, Fusobacteria, Firmicutes, and Proteobacteria were increased significantly in the SWF® group (P<0.05), whereas significant reduction of Actinobacteria was observed in the gut of the SWF® group compared with the control group (P<0.01). Moreover, at the end of the experiment the gut microbiota of sturgeon, were colonized to germ-free (GF) zebrafish for three days. Results indicated that, the expression of growth promoter genes mTOR, MyoD and Myogenin was significantly higher in GF zebrafish colonized with gut microbiota of SWF® group of sturgeon. Furthermore, TGF-β was increased significantly in GF zebrafish colonized with gut microbiota from SWF® group (P<0.01), whereas the expression of TNF-α was significantly decreased (P<0.05). The expression of non-specific immune related genes DEFBL-1, C3a and Lysozyme was significantly increased in GF zebrafish colonized with gut microbiota of sturgeon fed on SWF® (P<0.05). Group of GF zebrafish colonized with gut microbiota of sturgeon fed on SWF® had significantly higher survival rate against A. veronii Hm091 (P<0.05). Our study suggests that, the gut microbiota induced by SWF® played a great role in growth and disease resistance of sturgeon using GF zebrafish model.

Full-length transcriptome sequencing and comparative transcriptomic analysis to uncover genes involved in early gametogenesis in the gonads of Amur sturgeon (Acipenser schrenckii)

BackgroundSturgeons (Acipenseriformes) are polyploid chondrostean fish that constitute an important model species for studying development and evolution in vertebrates. To better understand the mechanisms of reproduction regulation in sturgeon, this study combined PacBio isoform sequencing (Iso-Seq) with Illumina short-read RNA-seq methods to discover full-length genes involved in early gametogenesis of the Amur sturgeon, Acipenser schrenckii.ResultsA total of 50.04 G subread bases were generated from two SMRT cells, and herein 164,618 nonredundant full-length transcripts (unigenes) were produced with an average length of 2782 bp from gonad tissues (three testes and four ovaries) from seven 3-year-old A. schrenckii individuals. The number of ovary-specific expressed unigenes was greater than those of testis (19,716 vs. 3028), and completely different KEGG pathways were significantly enriched between the ovary-biased and testis-biased DEUs. Importantly, 60 early gametogenesis-related genes (involving 755 unigenes) were successfully identified, and exactly 50% (30/60) genes of those showed significantly differential expression in testes and ovaries. Among these, the Amh and Gsdf with testis-biased expression, and the Foxl2 and Cyp19a with ovary-biased expression strongly suggested the important regulatory roles in spermatogenesis and oogenesis of A. schrenckii, respectively. We also found the four novel Sox9 transcript variants, which increase the numbers of regulatory genes and imply function complexity in early gametogenesis. Finally, a total of 236,672 AS events (involving 36,522 unigenes) were detected, and 10,556 putative long noncoding RNAs (lncRNAs) and 4339 predicted transcript factors (TFs) were also respectively identified, which were all significantly associated with the early gametogenesis of A. schrenckii.ConclusionsOverall, our results provide new genetic resources of full-length transcription data and information as a genomic-level reference for sturgeon. Crucially, we explored the comprehensive genetic characteristics that differ between the testes and ovaries of A. schrenckii in the early gametogenesis stage, which could provide candidate genes and theoretical basis for further the mechanisms of reproduction regulation of sturgeon.

Assessing gel properties of Amur sturgeon (Acipenser schrenckii) surimi prepared by high-temperature setting (40 °C) for different durations.

Setting effects are different for each fish species tested. There is no published literature on the response of Amur sturgeon (Acipenser schrenckii) to increased setting times. This study investigated the effects of high-temperature setting (40 °C) for different durations on the gel properties of A. schrenckii surimi. As A. schrenckii is a new surimi material, it is also necessary to conduct a sensory evaluation and to report the surimi yields. Increasing setting durations (0.5-1.5 h) significantly improved the gel properties. The best results in terms of molecular forces, gel strength, texture profile analysis (TPA), water holding capacity (WHC), and whiteness were obtained by the gels with setting durations of 1 and 1.5 h. The protein degradation detected as a result of extended setting durations (>2 h) significantly decreased the gel properties. The most inferior gel properties were shown by the gel with setting for 3 h. Protein degradation also resulted in higher cooking loss and poor microstructures. The sensory evaluation indicated that A. schrenckii surimi was generally accepted by the panelists in terms of color, texture, and aroma. The surimi yield obtained in this study was 32.4%, which was similar to commercial surimi and higher than several surimi yields in recent studies. Setting durations from 0.5 to 1.5 h can be implemented to improve the properties of A. schrenckii surimi. Extended durations (>2 h) must be avoided. Overall, this work provided some necessary information about setting response, gel properties, sensory evaluation, and surimi yield in A. schrenckii, which will be useful for further studies. © 2020 Society of Chemical Industry.

Amended diagnosis, validity and relationships of the genus Acrolichanus Ward, 1917 (Digenea: Allocreadiidae) based on the 28S rRNA gene, and observations on its lineage diversity.

Adult specimens of the allocreadiid trematode Acrolichanus auriculatus (Wedl, 1858) were collected from Acipenser schrenckii Brandt from the River Amur and Amur Estuary, Acipenser ruthenus L. from the Rivers Irtysh and Oka (Asian and European parts of Russia, respectively), and Acipenser fulvescens Rafinesque from Lake Winnebago, Wisconsin, USA, and used for phylogenetic analyses based on 28S rDNA sequence data. The results supported the monophyly of Acrolichanus populations from both continents and a clear separation of A. auriculatus from other allocreadiid taxa, thus supporting the validity of the genus Acrolichanus Ward, 1917. This study formally reestablishes the genus Acrolichanus. Species of this genus differ from other allocreadiids by the following combination of morphological features: triangular mouth opening with rounded posterior corners, simple ventral, dorsolateral and dorsomedian muscular lobes on the oral sucker, stout cirrus-sac, pars prostatica with dorsal pocket, and massive cirrus with conspicuous triradiate lumen when invaginated. Specimens of the trematode from North America and the Rivers Irtysh and Oka were more closely related to each other than to the specimens from River Amur and Amur Estuary. This reflects the evolutionary divergence among sturgeons into Pacific and Atlantic clades. The phylogenetic analyses also confirmed the paraphyly of the genus Crepidostomum Braun, 1900.

Growth of Hybrid Sturgeon Acipenser schrenckii♀×A. baeri♂ during Early Development

Growth of Hybrid Sturgeon Acipenser schrenckii♀×A. baeri♂ during Early Development

Synthesis of Tetrapeptides and Screening of their Antioxidant Properties

Background: Tetrapeptide Pro-Ala-Gly-Tyr (PAGY) is an antioxidant peptide that was isolated by Nikoo et al. (2014) from hydrolysate of skin gelatin of amur sturgeon fish (Acipenser schrenckii). This research aims to synthesize PAGY and its analogues by a solid-phase method, and to screen their antioxidant activities. Methods: PAGY and its analogues, namely, Pro-Ser-Gly-Tyr (PSGY), Pro-Ala-Phe-Tyr (PAFY), Pro- Phe-Phe-Tyr (PFFY) and Pro-Ala-Ile-Tyr (PAIY), were synthesized via a solid phase peptide synthesis method with the Fmoc/t-Bu strategy. The synthesis was undertaken on 2-chlorotritylchloride resin as solid support, and all coupling reactions were facilitated by a combination of HBTU and HOBt reagents. All peptides were cleaved from the resin by using 95% TFA in water. Results: Through the solid-phase synthesis method, all peptides were obtained in 50-85% yields. Pure peptides were analysed by analytical RP-HPLC, and were characterized by HR-TOF-ESI-MS and 1HNMR. DPPH inhibition assay was applied to all of the peptides with IC50 of 1.750; 1.116; 1.177 ;1.437; and 1.642 mg/mL for PAGY, PSGY, PAFY, PFFY, and PAIY, respectively. Conclusion: PAGY and its four analogs were successfully synthesized by solid-phase method. PSGY compound was found to have the highest activity of all in DPPH assay.

Gel properties of Amur sturgeon (Acipenser schrenckii) surimi improved by lecithin at reduced and regular-salt concentrations.

This study examined the gel properties of Acipenser schrenckii (A. schrenckii) surimi with 10 and 30 g kg−1 of added lecithin at reduced-salt (3 g kg−1 NaCl) and regular-salt (30 g kg−1 NaCl) concentrations. The results suggested that the gel properties of A. schrenckii surimi were strongly salt-dependent. Notably, regular-salt surimi gels showed better properties than reduced-salt surimi in all analyses. However, with the addition and increased levels of lecithin, the hydrogen bond formation and β-sheet content of low-salt surimi gels significantly increased (P < 0.05). The rheological patterns demonstrated higher elasticity and the gel strength, textural properties, and water holding capacity were also enhanced by lecithin (P < 0.05). The SEM analysis showed that the protein formation induced by lecithin was able to fill the empty voids and reinforce the microstructures. Unlike in reduced-salt surimi, the influence of higher salt concentration was more dominant in regular-salt surimi diminishing the effects of lecithin. The only adverse effect of lecithin found in this study was the decreasing of whiteness, especially when lecithin added up to 3% in both salt conditions. However, there was no significant damage to the overall gel properties.

Effects of waterless live transportation on survivability, physiological responses and flesh quality in Chinese farmed sturgeon (Acipenser schrenckii)

Waterless transport is an alternative method to realize the larger volume and higher survival rate of live aquatic products, this paper aims to investigate the effects of transport multi-stressors on the blood physiology and flesh quality, then optimize the setting of ambient parameters during waterless live transportation. Amur sturgeon, Acipenser schrenckii is selected as research objective because it is a representative fish of Chinese farmed sturgeon species. Fish were divided into three groups, Group I, Group II, and Group III. The fish in group I were cultured in the normal living environment (21 °C, with water), and Group II were transported in a lower temperature but normal living environment (4 °C, with water), but fish in Group III were transported in a waterless environment (4 °C, without water). Blood and muscle for assay were sampled at every 8 h intervals (0 h, 8 h, 16 h, 24 h and 32 h). The results indicate that temperature and oxygen are the critical ambient parameters in waterless live transportation, and significantly influence the fish survivability and blood physiology; blood glucose (GLU) and serum cortisol (COR) could be regarded as the representative indexes to assess the physiological stress level. Furthermore, the fish in waterless condition (Group III) exhibit no significant changes in flesh quality, such as total protein and crude fat after transport. These findings provide the theoretical evidence to understand the effects of multi-transport stressors on live fish and apply waterless transport in actual situation.

P.683 First episode psychosis outcome trajectories: The role of functioning and neurocognition

China has recently become the leader country for sturgeon aquaculture and caviar production, deeply changing the traditional geography of this market in few years. As a consequence, some species originating from the Far East Asia increased their economic relevance, joining the ones traditionally harvested for caviar. In this context, the possibility to reliably and promptly identify these species on the market has increasing importance for the enforcement of control actions against illegal trade or commercial frauds. The present study focuses on two commercially relevant species, massively reared in China not only as pure species but also as reciprocal hybrids: the Amur (Acipenser schrenckii) and Kaluga (Huso dauricus) sturgeons. We assess the identification power of two putatively diagnostic markers isolated from two predicted introns of the nuclear coding gene Ribosomal Protein L8. The markers were tested on tissue or caviar of 508 individuals of the two species and 31 hybrids. In order to compare results across loci, most individuals were also checked at two already published microsatellite markers, with a good, even if incomplete, identification efficiency for the two species. No marker showed fixed alternative alleles between Amur and Kaluga sturgeons, confirming the difficulty of distinguishing these two sympatric species in spite of the marked morphological differences and the consequent classification into different genera. So far, the multi-locus panel here used represents the more effective tool for the genetic identification of pure Amur and Kaluga sturgeons and resulted to be fully efficient to validate caviar and tissues obtained from hybrids between the two species.

Plant protein diet suppressed immune function by inhibiting spiral valve intestinal mucosal barrier integrity, anti-oxidation, apoptosis, autophagy and proliferation responses in amur sturgeon (Acipenser schrenckii)

An 8-week growth trial was conducted to investigate the effects of replacing dietary fishmeal with a plant protein blend on the growth performance, mucosal barrier integrity and the related regulation mechanism in Amur Sturgeon (Acipenser schrenckii) with initial weight of 87.48 g. Three isonitrogenous and isoenergetic diets were prepared. A basal diet containing 540 g/kg fishmeal (P0), whereas the other two diets were formulated by replacing 50% and 100% of FM with plant protein blend (soybean protein concentrate and cottonseed protein concentrate), and named as P50 and P100, respectively. Although essential amino acids, fatty acids, and available phosphorus had been balanced according to the nutrient requirement of sturgeon, compared with the fish of P0 and P50, the full plant protein diet (P100) significantly reduced growth performance and survival, and accompanied with serious spiral valve intestinal (SVI) damage. The increased tissue necrosis and failed responses in anti-oxidation, programming apoptosis, autophagy and cell proliferation system were regulated by inhibiting ERK1 phosphorylation, which indicated that SVI hypoimmunity and functional degradation were the main reasons for the high mortality and low utilization ability of plant protein in Amur sturgeon.

De novo Assembly and Analysis of Amur Sturgeon (Acipenser schrenckii) Transcriptome in Response to Mycobacterium Marinum Infection to Identify Putative Genes Involved in Immunity.

Fish mycobacteriosis is a common bacterial disease in many species of freshwater and marine fish and has caused severe loss of fish production. Mycobacterium marinum has been the most prevalent pathogen observed in several outbreaks of mycobacteriosis of farmed sturgeons in China. However, the immune responses and pathology of sturgeons in mycobacterial infection are rarely studied. Therefore, we used the Illumina RNA-seq method to analyze the transcriptome profile of Acipenser schrenckii challenged with Mycobacterium marinum. To begin, 168,220 non-redundant contigs were acquired from the infection and control groups, and among these, 33,225 contigs have acquired annotations. A total of 4,043 differently expressed (DE) contigs between the two groups were identified, and among these, 2479 were upregulated and 1564 were down-regulated in the infected fish. A total of 1,340 DE contigs with acquired annotations in KEGG were enriched for 124 pathways including the TNF signaling pathway, and the Toll-like receptor signaling pathway. The roles of DE genes involved in significant pathways and other processes were discussed. The 2,209 DE contigs that have yet to acquire proper annotation may represent candidate genes associated with infection in sturgeons and are expected to serve as immunogenetic resources for further study. To our best knowledge, this is the first transcriptome study on sturgeons under bacterial infection.

Properties of collagen extracted from Amur sturgeon Acipenser schrenckii and assessment of collagen fibrils in vitro

The objective of this study was to assess the nature of the collagens from the Amur sturgeon to determine its possibility as a potential collagen source for biomedical applications. From a sturgeon (1.22 kg), 6.0 g (dry wt) of skin collagen (SC), 4.1 g of swim bladder collagen (SBC), and 0.4 g of notochord collagen (NC) were obtained. SC and SBC were characterized as type I, and NC as type II collagen. Denaturation temperatures of SC, SBC, and NC were calculated as 28.5, 30.5, and 33.5 °C, respectively. Gene expression of the type I procollagen α2 chain of Amur sturgeon (ascol1a2) was specifically higher than ascol1a1 expression in the swim bladder, suggesting a unique composition of α chains in this organ. SC and SBC had better abilities of fibril formation with unique higher-order structures compared with porcine type I collagen. The maximum transition temperature (Tm) of reassembled fibrils formed in a buffer solution containing NaCl at 0 and 140 mM was 34.4 °C and 38.9 °C in SC, and 40.1 °C and 40.7 °C in SBC, respectively. These characteristic features suggested that sturgeon collagens could be used in the biomedical industries in future applications.