Gut Peculiarities of Feed Deprived White Sturgeons (<i>Acipenser transmontanus</i>, Richardson 1836)

In the White sturgeon fish farms, some individuals have difficulty in getting access to food: such sturgeons are called "runts", and they result in a slower growth rate than normally feeding fish. In this paper, we have studied the gut peculiarities of runt sturgeons. Utilizing in paralleling an analysis of diatom populations in both the fish gut tissues and the rearing tank waters, we hypothesized a causative relation between the occurrence of runt sturgeons and periodic diatom blooms. In fact, we have observed that the diatom species identified in the aquatic environment were also detected in organs (Fragilaria spp and Rhoicosfenia spp for both glandular body, mid-intestine) of the runt sturgeon's gut, but not in tissues of normally feeding individuals. Owing to their siliceous wall, diatoms can be responsible for areas of epithetlial detachment in the mucosal surfaces of the alimentary canal and a catharral inflammation in both the gastric pits and intestinal folds which may be the cause of secondary bacterial diseases. We suggest that diatom blooms may contribute to the occurrence of runt sturgeons in the studied Italian fish farm.

Determining the specific status of the Iberian sturgeons by means genetic analyses of old specimens

To clarify the species status of sturgeon from rivers of the Iberian Peninsula, eight molecular markers (4 nuclear and 4 mitochondrial) have been analysed in different specimens from historical museum samples and prehistoric samples from archaeological sites. These analyses indicate that one of these specimens (UGP captured in the Guadalquivir River in the 19th century) is A. sturio, based on all the eight molecular markers, four of them used from the first time in this study. In previous analyses based on 5 genetic markers, our group assigned two specimens captured in this river in the 1970-80s (EBD8173 and EBD8401) to the species A. naccarii, suggesting the presence of this species in the Iberian Peninsula. In this work, this conclusion is drawn after successfully obtaining a mitochondrial marker in a very old scute from a prehistoric site (Acinipo, about 1500 BC, from the Guadalquivir River basin). On the other hand, in the specimen EBD8174 captured in the Guadalquivir in 1975, we have obtained two new mitochondrial markers confirming that it can be considered A. sturio for all the mitochondrial markers, but nuclear ones identify it as A. naccarii. Finally, two very old samples (Nerja E-VI and Nerja N/62-63) were not successfully characterized by any molecular markers. Some aspects and consequences of our results are discussed, such as the origin of the “mosaic” specimen EBD8174 and, above all, the native status of A. naccarii in historic and prehistoric times in the southern Iberian Peninsula.

Use of electrosense in the feeding behavior of sturgeons

The electro-receptive lateral line system appeared early in the evolutionary history of fish.Sturgeons,members of the primitive Chondrostei group,are known for their electroreceptors(ampullae of Lorenzini)on the head,which are thought to be sensitive to weak electric fields in aquatic environments and involved in feeding,mating and migration.Here,we report the results of a set of behavioral and electrophysiological experiments designed to determine the function and characteristics of the electrosense in cultured sturgeons.The results showed Sibe-rian sturgeon(Acipenser baerii Brandt,1869)feeding striking at bio-electric fields produced by living feed-fish enclosed in a gel chamber and at the corrosion field produced by metal rods.With an electric stimulus that mim-ics the bio-electric fields produced by living prey,the relative discharge rate of electrosensory neurons in the dorsal octavolateralis nucleus(DON)was modulated by and phase-locked to sinusoidal stimulus and some units showed selectivity for dipolar direction in white sturgeon(Acipenser transmontanus Richardson,1836).This is the first study to provide the empirical evidence correlating with electrosensory behaviors and electrophysiolog-ical responses in cultured sturgeons,and suggesting that electrosense does play an innate role in feeding behav-ior of sturgeon.We believe this will have important implications for protecting sturgeons in the wild.

Purifi cation and identification of anti-inflammatory peptides from sturgeon (Acipenser schrenckii) cartilage

Cartilage is a nonedible byproduct with little saleable value.However,previous studies have proposed the possibility of producing peptides from cartilage with immune function modulation potential.The current study aimed to investigate the potential anti-inflammatory activity of peptides derived from sturgeon(Acipenser schrenckii)cartilage in lipopolysaccharide(LPS)-stimulated RAW264.7 macrophages.Five peptide sequences,including four novel peptides,were identified from ethanol-soluble cartilage hydrolysates.Among these five peptides,LTGP,LLLE,LLEL and VGPAGPAGP reduced the production of nitric oxide(NO)and interleukin-6(IL-6)while increasing interleukin-10(IL-10)excretion.Transcriptome analysis suggested the inhibition of activated mitogen-activated protein kinase(MAPK)and interleukin-17(IL-17)signaling pathways after LLEL intervention.MAPK,which is involved in the IL-17 signaling pathway,was further proved to be blocked by downregulating the phosphorylation of p38,extracellular-signal regulated protein kinase(ERK),and c-jun N-terminal kinase(JNK).This novel peptide offers an attractive approach to develop functional foods.

Impact of the Three Gorges Dam on the spawning stock and natural reproduction of Chinese sturgeon in the Changjiang River,China

Chinese sturgeon(Acipenser sinensis) is the flagship species of the Changjiang River.The migration route of this species is blocked by the first dam,the Gezhou Dam,and its reproduction is affected by the Three Gorges Dam(TGD),one of the largest dams in the world.We studied the impact of the impoundment of the Three Gorges Reservoir(TGR) since 2003 on the spawning stock and the natural reproduction of the Chinese sturgeon by using our monitoring data from 1997 to 2013.Results indicate that TGR impoundment has delayed the first spawning dates of the fish from middle-late October to late November,decreased the amount of spawning activities from twice to only once each year,and significantly reduced egg production.In particular,the fish did not demonstrate any spawning activities in 2013.Therefore,TGR impoundment significantly affects the natural reproduction of the fish downstream of the TGD.The spawning stock size of the fish is also predicted to further decrease in the future,which will lead to a risk of population extinction.Ecological regulations must be imposed on decreasing the water temperature to 20℃before mid-October and increasing water discharge downstream of the TGD in October to induce spawning of the Chinese sturgeon.

Isolation and Characterization of Acid-soluble Collagen and Pepsin-soluble Collagen from the Skin of Hybrid Sturgeon

By using the wastes fish skin of sturgeon processed as a raw material, a macromolecule biomaterial of collagen was extracted. Acid-soluble collagen(ASC) and pepsin-soluble collagen(PSC) were successfully isolated from the skin of hybrid sturgeon with two extraction methods. The yields of ASC and PSC based on the wet weight of skin were 5.73 ± 0.11% and 10.26 ± 0.39%, respectively. The denaturation and melting points of ASC(26.83 ℃ and 110.49 ℃) and PSC(26.54 ℃ and 102.99 ℃) were assessed by Circular dichroism(CD) and Differential scanning calorimetry(DSC). ASC and PSC appeared to be dense sheet-like film linked by random-coiled filaments under scanning electron microscopy(SEM). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis(SDS-PAGE) and Fourier transform infrared spectroscopy(FTIR) confirmed that both the ASC and PSC were Type I collagen and maintained a complete triple helix structure. These results indicated that both ASC and PSC possessed good biological activity and could be widely used in medical biomaterials and other fields.

Peptide fraction from sturgeon muscle by pepsin hydrolysis exerts anti-inflammatory effects in LPS-stimulated RAW264.7 macrophages via MAPK and NF-κB pathways

Previous studies have suggested that polypeptides extracted from milk, soybean, fish, eggs, and meat possess potential anti-inflammatory effects. To date, few studies have reported the anti-inflammatory function of sturgeon peptides and their underlying mechanisms are unknown. The current study was therefore to determine the anti-inflammatory potential of sturgeon peptides with lipopolysaccharide (LPS)-induced RAW264.7 inflammatory model. Pepsin hydrolysate (PeH) was purified by ultrafiltration and Sephadex G-15 gel filtration chromatography. PeH significantly reduced the inflammatory mediator (NO) and inflammatory cytokines (IL-6, TNF-α and IL-1β) expression in a dose-dependent manner. Moreover, the purified sturgeon peptide (F2) possessed strong antioxidant potential and effectively inhibited DPPH and ABTS free radicals. F2 significantly suppressed the expression of MAPK, IκBα, and NF-κB p65, indicating that F2 exerted anti-inflammatory influence by the inhibition of MAPK and NF-κB pathways.

A review of sturgeon virosis

Sturgeon, as a kind of rare large-scale economic fish, has high scientific research and commercial value. But virosis was a sig- nificant cause of mortality among farm-raised juvenile sturgeon, which brought tremendous loss in the last decades. In this paper, we re- viewed the studies on four sturgeon viruses: white sturgeon (Acipenser transmontanus) iridovirus (WSIV), white sturgeon herpesvirus-1,2 (WSHV-1,2) and shovelnose sturgeon (Scaphirhynchus Scaphirhynchus) iridovirus (SSIV). The content of this review were mainly focused on clinic symptom of infected fish, diagnostic method, virus isolation, prophylactic and remedy. Based on a detailed conclusion and analysis, it is reasonable that molecular biology techniques might be a potential method for sturgeon virosis diagnosis.

Stocking density affects the growth performance and metabolism of Amur sturgeon by regulating expression of genes in the GH/IGF axis

The effects of stocking density on the growth and metabolism of Amur sturgeon were assessed. Amur sturgeon were grown for 70 days at three dif ferent stocking densities(low stocking density, LSD: 5.5 kg/m^3; medium stocking density, MSD: 8.0 kg/m^3; and high stocking density, HSD: 11.0 kg/m^3), and the biometric index, muscle composition, and serum biochemical parameters were evaluated. In addition, pituitary, liver, and muscle samples were collected for gene cloning and expression analyses. After 70 days of growth, the fish maintained at HSD had significantly lower fi nal body weight and specifi c growth rate, and a higher feed conversion ratio than those of the fish in the MSD and LSD groups. The HSD group had the lowest lipid and protein concentrations in serum and muscle. The serum cortisol concentration increased significantly in the HSD group, indicating that the stress-response system was activated in these fish. There was no change in the concentration of serum insulin-like growth factor 2(IGF-2), while the concentrations of serum growth hormone(GH) and insulin-like growth factor 1(IGF-1) decreased in the HSD group. The full-length cDNAs of G H and IGF-2 genes(995-bp and 1 207-bp long, respectively), were cloned and analyzed. In the HSD group, the expressions of GH in the pituitary and growth hormone receptor( GHR) and IGF-1 in the liver were down-regulated at the end of the 70-day experiment. In the HSD group, the transcript level of IGF-2 significantly decreased in the liver, but did not change in muscle. Overall, our results indicated that a HSD negatively af fects the growth performance and leads to changes in lipid and protein metabolism in Amur sturgeon. The down-regulated expression of genes related to the GH/IGF axis may be responsible for the poor growth performance of Amur sturgeon under crowding stress.

Changes in growth and osmoregulation during acclimation to saltwater in juvenile Amur sturgeon Acipenser schrenckii

We evaluated the ability of juvenile Amur sturgeon (Acipenser schrenckii) to osmoregulate and grow in saltwater. Hatchery-reared juveniles (mean weight 106.8 g, 5-month old) were transferred from freshwater to 10, 20, and 25 salinity saltwater over a period of 20 d. We measured the growth, serum osmolality, ion concentrations, and Na+/K+-ATPase activity. In addition, we prepared samples of gill tissue to quantify morphological changes in gill ultrastructure. Rearing in up to 25 saltwater for 30 d had no significant effect on growth. Similarly, serum osmolality and ion concentrations were similar to levels reported in other teleosts following acclimation to saltwater. Serum osmolality and Na+, Cl- concentrations increased significantly with the initial increase in salinity. Afterwards, levels tended to stabilize and then decrease. Serum K+ levels did not change during acclimation to saltwater. Gill Na+/K+-ATPase activity increased initially as salinity was increased. However, the activity later decreased and, finally stabilized at 3.7±0.1 μmol Pi/mg·prot·h in 25 saltwater (1.6 times higher than the level in those in freshwater). In fish that were held only in freshwater, the chloride cells were located in the interlamellar regions of the filament and at the base of the lamella. Following acclimation to 25 saltwater for 30 d, the number and size of chloride cells increased significantly. Our results suggest that juvenile Amur sturgeon is able to tolerate, and grow in, relatively high concentrations of saltwater.

Effects of the Chinese Medicinal Herb Com plex Additives on Non-specific Immunity of Amursturgeon( Acipenser schrencki Brandt)

This study was to investigate the effects of aqueous decotion from three Chinese medicinal herb additives （ Cyrtomium fortunei, prescription I and prescription II） on non-specific immunity of 1 ＋ age old Amur sturgeon （Acipenser schrencki Brandt） by oral perfusion. Cyrtomiumfortunei, prescription I and prescription II were orally given to 15 fishes for each experimental group once a day, with the concentration of 9,175 and 36 g/S0 kg body weight, respectively. The administration was lasted for 14 days. Meanwhile, distilled water was orally given as the control. After the experiment, some of the experimental fishes were stimulated with high temperature （30 ℃ ） for two hours. Sampling was performed from fishes treated at 22 ℃ and 30 ℃ for measuring the protein content in the serum, phagocytic activity of leucocytes and the activity of the lysozyme in six tissues. The results indicated that Cyrtomiumfortunei and prescription II could help to enhance the content of various proteins and the phagocytic activity of leucocytes. There was no significant change in the effects between these two additives at either the normal temperature or high temperature. Prescription I did not show an obvious effect on the immunity of fishes at the normal temperature, but it did in promo- ting high-efficiency response and improving immunoregulation of fish shocked by some stimuli.

Effects of Norfloxacin on the Superoxide Dismutase Activities of 2 Sturgeon Species

[Objective]This study was to investigate the effect of different concentrations of Norfloxacin on the superoxide dismutase （ SOD） activities in the blood plasma and liver tissues of Amur sturgeon （ Acipenser schrencki Brandt） and sterlet （ Acipenser ruthenus Linnaeus） . [Method] Using pharmaco-toxicological evaluation method,Norfloxacin with the concentrations of 0,20,40,60,80 and 100 mg /kg,was orally delivered to the Amur sturgeon and sterlet for 5 d,respectively. The SOD activities in the blood plasma and liver tissues were measured after drug withdrawal for 2 d to explore the optimal dosing concentration of Norfloxacin during sturgeon culture,as well as the effect of Norfloxacin on liver injury. [Result] SOD existed in both two sturgeons but with different amounts,and the SOD activities were higher in the livers than in the blood plasma no matter in the control and all drug delivered groups. Under different drug delivery concentrations,the SOD activities first increased and then decreased in the 2 tissues of the 2 sturgeon species,and the SOD activities reached the maximum when the drug delivery concentration was 40 mg /kg. The drug de- livery concentration had little effect on the SOD activities in the blood plasma,which showed stable changes. When the drug delivery concentration was 40 mg /kg,the SOD activities in the blood plasma of Amur sturgeon were higher than that of sterlet,while for the other concentrations,the SOD activities in the plasma of sterlet showed higher performance. However,the SOD activities changed significantly through drug delivery in the liver tis- sues,and the SOD activities were higher in the sterlet than in the Amur sturgeon when the drug delivery concentrations were 0,40 and 100 mg /kg. The SOD activity in the sterlet was the highest under 40 mg /kg,presenting a sharp peak value. The optimal drug delivery concentration of Norfloxa- cin was 30 -50 mg /kg,under which the Norfloxacin presented best effect and had no injury effect on livers. [Conclusion]This study provides theo- retical basis for the reasonable application of Norfloxacin in aquaculture.

Nitric oxide-factor, which regulates proliferation and apoptosis in the adult brain of amur sturgeon <i>Acipenser schrenckii</i>

The distribution of proliferative zones, NO-producing cells and apoptosis areas in the medulla oblongata, cerebellum, optic tectum, thalamus and hypothalamus of Amur sturgeon Acipenser schrenckii was investigated, using techniques of immunoperoxidase staining of proliferating cell nuclear antigen (PCNA), neuronal nitric oxide synthase and TU-NEL-labeling of fragmented DNA. It has been established, that in the sturgeon brain NO can act both as a cytotoxic proapoptogenic factor, and as a factor, which stimulates cell proliferation. The presence of NO-producing elements in somato- and viscerosensory areas of medulla oblongata, tectum, cerebellum and thalamus suppose, that in these brain areas NO constitutes apoptogenic factor, which induces the cells death in a territory of postmitotic neuroblasts, renders controlling effect on development and differentiating of chemosensory, visual, motor and hypophysotropic brain areas in postnatal ontogenesis. Maximal proliferating activity and high concentration of NO-ergic cells were revealed in external layers, adjoining to the medullar, cerebellar and tectum membranes, that allow to suppose NO participation in postnatal morphogenesis of these brain structures as a factor, which regulates cell proliferation. In sensory centers (tectum and nuclei of the V, VII, and X nerves), significantly varying ratios of intensities of proliferation and apoptosis were found;this is indicative of dissimilar rates of growth and differentiation in visual and chemosensory centers of the sturgeon brain. Presence of NO-producing elements in the PCNA- immuno-labeling and TUNEL-labeling brain areas allow to consider NO as a factor, which balances processes of proliferation and apoptosis in the sturgeon brain.

Isolation of Sturgeon Peripheral Blood Lymphocytes and the Optimal Proliferation Response Conditions

In this study, sterlet （ Acipenser ruthenus ） was chosen as the model species of sturgeon, different solutions were used to isolate the sturgeon peripheral blood lymphocytes and study their optimal proliferate response condition. Phytohemagglutinin （PHA）, concanavalin A （ConA）and lipopolysaccharide （LPS） were used as lymphocyte proliferation mitogen, respectively. According to L 25 （5^6） five-factor five-level orthogonal experimental design, the conditions for sturgeons proliferation response of peripheral blood lymphocytes were optimized using enhanced cell counting Kit-8 （enhanced CCK-8 or WST-8）. Five factors were selected to explore the optimal response conditions, including culture time, culture temperature, cell concentration, fetal bovine serum （FBS） concentration, and mitogen concentration. The results showed that 70% Percoll （1.092 g/ml） used as the sturgeon lymphocyte separation solution had the best separating effect. The optimal proliferation conditions were as follows： 3.625×10 6 initial cells, 20 μg/ml PHA or 50 μg/ml ConA or 10 μg/ml LPS as mitogen, 10%-20% FBS, the temperature at 20-25 ℃, and the culture time of 2 d.

Sturgeon (Acipenser gueldenstaedtii) Acclimatization to Optimal Growth Conditions—A Case Study of Adaptation, Nutrition, Reproduction, and Sex Determination

The development of new agricultural industries is an important challenge for a region’s economic establishment. The connection between a research department at MIGAL Institute and biotechnology in aquaculture is an example (case study) of the interrelationships that also exist in other departments. This article describes the research conducted by the institute supporting the development of the aquaculture industry in Israel through the introduction of a relatively new fish species—the Russian sturgeon (Acipenser gueldenstaedtii), with the relevant information to be used for acclimatization to aquaculture conditions in northern Israel. Many aspects related to bringing a new species to Israel and working with this new industry to study its adaptation to existing conditions in the north of the country influenced the economic success of this new type of precision agriculture. This article describes the research on various aspects affecting the successful acclimatization of Russian sturgeon in northern Israel: introduction, food development, reproduction, hormone systems that control reproduction and growth, gonadal development, and molecular markers for sex determination, differentiation, and economic assessment of caviar production.

SAVING A SPECIES Conservation and breeding of the Chinese sturgeon in the Yangtze River

"Chinese sturgeons, safe journeys!""You’ve eaten well but now you’re on your own.""Keep going all the way to the sea,regardless of wind or rain!"So went real-time online comments displayed during the livestream of an April 22 event in Yichang, central China’s Hubei Province。

Whole-genome Sequencing Reveals Autooctoploidy in Chinese Sturgeon and Its Evolutionary Trajectories

The order Acipenseriformes,which includes sturgeons and paddlefishes,represents“living fossils”with complex genomes that are good models for understanding whole-genome duplication(WGD)and ploidy evolution in fishes.Here,we sequenced and assembled the first high-quality chromosome-level genome for the complex octoploid Acipenser sinensis(Chinese sturgeon),a critically endangered species that also represents a poorly understood ploidy group in Acipenseriformes.Our results show that A.sinensis is a complex autooctoploid species containing four kinds of octovalents(8n),a hexavalent(6n),two tetravalents(4n),and a divalent(2n).An analysis taking into account delayed rediploidization reveals that the octoploid genome composition of Chinese sturgeon results from two rounds of homologous WGDs,and further provides insights into the timing of its ploidy evolution.This study provides the first octoploid genome resource of Acipenseriformes for understanding ploidy compositions and evolutionary trajectories of polyploid fishes.

Sturgeon and paddlefish:Review of research on broodstock and early life stage management

Sturgeon aquaculture has taken a parallel yet unique path relative to other teleost rearing.One of the driving factors has been the fact that virtually all extant species are facing extinction;thus,laws concerning the transport and processing of sturgeon are stringent.As a result,most sturgeon companies vertically integrate the farming process from hatchery to harvest,in contrast to the production of other commercial fish species(e.g.,trout,sea bass,salmon),where farmers tend to purchase fry from producers specialized only in the production of that life stage and sell product to unaffiliated fish processors.Sturgeon aquaculture is furthermore unique in the extremely high value of the main product(caviar).The secondary product(meat)also surpasses other finfish aquaculture products’average price per weight.These expensive outputs reveal the greatest challenge in production-an exceptionally long time to market from larvae to harvestable adults.For all their rigor and robustness as juveniles and adults,sturgeon species are highly fragile during larval stages.Due to the unique legal framework around sturgeon cultivation,aquaculturists often specialize in regional species,although some hybrids have achieved global popularity.This lends to a heterogenous swath of literature on best cultivation and management practices,especially at early growth stages.Nonetheless,the role of aquaculture as both a food source and restocking program to thwart further extinction of sturgeon species has hardly been fully tapped.In light of the many challenges,this review examines recent advances in sturgeon farming with an emphasis on broodstock and early life-stage management to summarize studies that can help researchers and farmers assess the industry’s current state.

Response properties of the electrosensory neurons in hindbrain of the white sturgeon,Acipenser transmontanus

Objective The passive electrosense is a primitive sensory modality in the Chondrostei, which include sturgeon and paddlefish. Using electroreceptors, these fish detect the weak electric fields from other animals or geoelectric sources, and use this information for prey detection or other behaviors. The primary afferent fibers innervating the electroreceptors project to a single hindbrain target called the dorsal octavolateral nucleus （DON）, where the electrosensory information is first processed. Here, we investigated the electrophysiological properties of DON neurons. Methods Extracellular recording was used to investigate the response properties of DON neurons to dipole electric fields with different amplitudes and frequencies in the white sturgeon, Acipenser transmontanus. Results The DON neurons showed regular spontaneous activity and could be classified into two types： neurons with a low spontaneous rate （〈10 Hz） and those with a high spon- taneous rate （〉10 Hz）. In response to sinusoidal electric field stimuli, DON neurons showed sinusoidally-modulated and phase-locked firing. In addition, neurons showed opposite phase responses corresponding to the different directions of the dipole. Conclusion The response properties of DON neurons match the electrosensory biological function in sturgeon, as they match the characteristics of the electric fields of its prey.

Phylogeny of nucleus medianus of the posterior tubercle in ray-finned fishes

The brains of ray-finned fishes form a morphocline of increasing complexity,from cladistians through teleosts.This is particularly apparent in the posterior tubercle of the diencephalon.In cladistians,the posterior tubercle consists of a periventricular nucleus and a migrated nucleus medianus that is fused across the midline.In more advanced ray-finned fishes,such as gars and bowfins,the posterior tubercle comprises numerous additional mi-grated nuclei,termed the preglomerular complex,in addition to a more well developed nucleus medianus.In teleosts,the most derived ray-finned fishes,there is an even more elaborate preglomerular complex,but there is no recognizable nucleus medianus.In an attempt to explain the variation in the posterior tubercle of the diencephalon in ray-finned fishes,the immunohistochemistry and connections of nucleus medianus were examined in cladistians,gars and bowfins.In each of these taxa,nucleus medianus exhibits large numbers of calretinin-positive neurons and has ascending projections that terminate in several divisions of the pallium.Although teleosts,such as goldfish,also exhibit numerous cell groups in the posterior tubercle that are rich in calretinin,none of these cell groups has connections that are comparable to those of nucleus medianus in non-teleost ray-finned fishes.It is possible,therefore,that nucleus medianus was lost with the origin of teleosts.