Sturgeon Aquaculture Research Articles

Identification of genes involved in gonadal sex differentiation and the dimorphic expression pattern in undifferentiated gonads of Russian sturgeonAcipenser gueldenstaedtiiBrandt & Ratzeburg, 1833

Summary The establishment of a sexing technique at an early developmental stage is an important issue in sturgeon aquaculture, yet the mechanism of sex differentiation in sturgeons remains poorly understood. This study aimed to identify genes involved in gonadal sex differentiation and to investigate sexually dimorphic gene expression in undifferentiated gonads. RNA-seq analyses using next-generation sequencers were carried out on undifferentiated gonads of five 9-month-old juvenile Russian sturgeon Acipenser gueldenstaedtii. A total of 45 686 832 (8498 Mb) and 79 743 269 (7887 Mb) quality-controlled reads were obtained using Ion PGM and HiSeq 2000 sequencers, respectively, and were assembled into 338 648 contigs (N50: 532 b). tBLASTx analyses identified 26 transcripts potentially involved in gonadal differentiation. Read-mapping analyses were performed to obtain relative transcript levels (RPKM values). Multivariate analyses of the RPKM values of five transcripts (gsdf, dmrt1a, dmrt1b, foxl2 and cyp19a1a) showed that the five individuals could be separated into two distinct groups. One group, comprising two individuals, had increased levels of foxl2, hsd17b1 and cyp19a1a, suggesting differentiation into females. Alternatively, levels of gsdf were higher in the other three individuals, suggesting differentiation into males. We describe the levels of 26 transcripts potentially involved in gonadal differentiation in undifferentiated sturgeon gonads and suggest that levels of gsdf, foxl2, hsd17b1 and cyp19a1a are appropriate sexing markers for sturgeon at an early developmental stage.

Ontogeny of the immune system in Acipenserid juveniles

Sturgeon aquaculture has increased considerably worldwide but little is known about their immunological development and competence in early life stages. Culture of larvae is one of the most critical stages in intensive sturgeon farming, often associated with high mortality rates. The objective of this study was to characterize the developmental morphology (light and transmission electron microscopy, LM and TEM) of the meningeal myeloid tissue, spleen and thymus in Atlantic sturgeon (Acipenser oxyrinchus oxyrinchus) from hatching until 5months old (2895°C·day(dd)). The spleen was first visible on 541dd larvae LM sections and the other two immune organs in 768dd samples (approximately 400 and 600dd after onset of feeding). Generally, younger fish had significantly higher percentages of undifferentiated cells (meningeal myeloid tissue and spleen) and effective adaptive immune competence would not be expected in these fish on the onset of feeding, but further functional immune assessment is needed.

Comparing Ultrasonography and Endoscopy for Early Gender Identification of Juvenile Siberian Sturgeon

AbstractEarly gender identification is economically advantageous in sturgeon aquaculture to facilitate the targeting of food and spatial resources to females for caviar production. In addition, many species of free‐ranging sturgeon are threatened or critically endangered, and the ability to identify gender and evaluate gonads can reveal pertinent biological information that can lead to better management and recovery plans. We compared the speed and accuracy of ultrasonography and endoscopy in identifying gender in 143 juvenile Siberian Sturgeon Acipenser baeri using gonadal histology as the gold standard. The age‐3 and age‐4 sturgeon were anesthetized with buffered tricaine methanesulfonate and evaluated using ultrasonography and endoscopy; endoscopic gonadal biopsy was then done for histologic confirmation. All fish recovered normally, and there was no postprocedural morbidity or mortality. Histology confirmed the gender for 128 of the 140 (91.4%) fish. Histology and endoscopy agreed on the gender of 124 of the 128 (96.9%) fish, while histology and ultrasonography agreed on 113 of the 128 (88.3%) fish. Ultrasonography (mean time, 11.2 s) was significantly faster than endoscopy (22.3 s), while endoscopy was more accurate but more invasive. Diagnostic accuracy, speed, and invasiveness are factors to consider when selecting a method of gender identification for commercial and free‐ranging populations.

Gender Identification in Great Sturgeon (Huso huso) Using Morphology, Sex Steroids, Histology and Endoscopy

Gender identification of great sturgeon during different life stages was conducted using morphology, sex steroid concentrations, histological and endoscopic techniques. One hundred and forty great sturgeons from two sturgeon farms at ages between 3-16 years were selected for examination. Most of the morphological indices showed no significant sex-related differences except for the ratio of fork length to distance of snout to anterior of dorsal fin (PD). The urogenital opening had no difference in shapes for both sexes. Mean sex steroid concentrations showed no significant difference in levels of testosterone, estradiol and progesterone between males and females in the stage II of maturity. 95.8% of fish were correctly sexed using endoscopy at this stage. Histological investigation indicated the ovaries of 3- to 9-year-old females were at the different stages of pre-vitellogenic, and most males were at the early spermatogenesis for age 3. The result of this study suggests that endoscopy is a reliable tool for sex and stage determination after the age of 3 years. This method is useful in providing a quick discernment of sexes and stages compared with utilizing morphometric and blood indices. Direct observation of gonads can give us important information about the gonadal and maturity stages in sturgeon aquaculture and wild population management, with minimal damage or stress to this endangered species.

Transcriptome sequencing and de novo annotation of the critically endangered Adriatic sturgeon

BackgroundSturgeons are a group of Condrostean fish with very high evolutionary, economical and conservation interest. The eggs of these living fossils represent one of the most high prized foods of animal origin. The intense fishing pressure on wild stocks to harvest caviar has caused in the last decades a dramatic decline of their distribution and abundance leading the International Union for Conservation of Nature to list them as the more endangered group of species. As a direct consequence, world-wide efforts have been made to develop sturgeon aquaculture programmes for caviar production. In this context, the characterization of the genes involved in sex determination could provide relevant information for the selective farming of the more profitable females.ResultsThe 454 sequencing of two cDNA libraries from the gonads and brain of one male and one female full-sib A. naccarii, yielded 182,066 and 167,776 reads respectively, which, after strict quality control, were iterative assembled into more than 55,000 high quality ESTs. The average per-base coverage reached by assembling the two libraries was 4X. The multi-step annotation process resulted in 16% successfully annotated sequences with GO terms. We screened the transcriptome for 32 sex-related genes and highlighted 7 genes that are potentially specifically expressed, 5 in male and 2 in females, at the first life stage at which sex is histologically identifiable. In addition we identified 21,791 putative EST-linked SNPs and 5,295 SSRs.ConclusionsThis study represents the first large massive release of sturgeon transcriptome information that we organized into the public database AnaccariiBase, which is freely available at http://compgen.bio.unipd.it/anaccariibase/. This transcriptomic data represents an important source of information for further studies on sturgeon species. The hundreds of putative EST-linked molecular makers discovered in this study will be invaluable for sturgeon reintroduction and breeding programs.

Sturgeon Aquaculture--Specialized Techniques: Determining the Sex of Sturgeon by Direct Examination of the Gonad Using a Minimally Invasive Surgical Procedure

Because male sturgeon are harvested for meat at 2-4 years of age and females are retained for caviar production, being able to determine the sex of individual sturgeon has specific economical advantages. But it is difficult to tell females from males, especially when the fish are young (from hatch to 3 years old). This 5-page fact sheet describes the standard method and tools for determining the sex of sturgeon by direct examination of the gonad using a minimally invasive surgical procedure. Written by Frank A. Chapman and Joel P. Van Eenennaam, and published by the UF Department of Fisheries and Aquatic Sciences, November 2012. FA183/FA183: Sturgeon Aquaculture—Specialized Techniques: Determining the Sex of Sturgeon by Direct Examination of the Gonad Using a Minimally Invasive Surgical Procedure (ufl.edu)

Sperm biology and control of reproduction in sturgeon: (I) testicular development, sperm maturation and seminal plasma characteristics

Sturgeon (Chondrostei, Acipenseriformes) are threatened or endangered species due to overfishing and environmental degradation causing disruption of natural reproduction. Commercial sturgeon aquaculture and conservation program requires broodfish management as well as biogeographical and biological knowledge. Therefore, control of sturgeon reproduction in captivity can become as a valid tool in the field of sustainable development. The main objectives of the present review were to summarize, describe and synthesize available data about neuroendocrine control of testicular development, spermiation induction, seminal plasma characteristics and factors affecting sperm quality. In sturgeon, puberty usually occurs late in life and adult males do not spawn on an annual basis. Gonadal differentiation and spermatogonia proliferation occurs at 1–2 and 2–3 year-old, respectively. In spermatogenesis, environmental stimuli affect hypothalamus to release GnRH, which induce FSH release from pituitary stimulating testicular androgenesis, which is involved in spermatogonial proliferation and spermatogenesis. At spawning season, GnRH stimulates LH production from pituitary, regulating 17α,20β-dihydroxy-4-pregnen-3-one production in testis, which control sperm maturation. In captivity, hormonal treatment is essential to induce spermiation. Chemical and biochemical compounds of the seminal plasma are important to protect viability, motility and fertilizing capacity of spermatozoa. Several kinds of acrosomal enzymes have been identified in sturgeon seminal plasma; higher concentrations reported in the frozen/thawed than fresh sperm suggesting their origination from spermatozoa. Moreover, there are numerous factors that influence on sperm quality including temperature, methods for spermiation induction, stripping frequency and stress.

Spermatozoa motility, cryoresistance, and fertilizing ability in sterlet Acipenser ruthenus during sequential stripping

We describe spermatozoa characteristics from sequential collections in sterlet, Acipenser ruthenus, following a single dose of carp pituitary extract (CPE). Sperm production and spermatozoa fertilizing ability, percent motility, and curvilinear velocity (VCL) were investigated in fresh and frozen/thawed sperm. Sperm was collected by two procedures: (A) stripping 3 times per 24h at 3h intervals on 3 consecutive days beginning 12h after CPE treatment, and (B) stripping 3 times over 6h beginning 36h after CPE treatment. Spermatozoa motility and VCL were evaluated by video microscopy, and sperm production was measured as volume and concentration. Sperm samples were frozen by a conventional freezing procedure in a cryoprotective medium containing 10% methanol. Fertilization was conducted using a ratio of 105 spermatozoa/egg. Both sequential stripping procedures yielded larger volumes of viable spermatozoa than did a single collection. Sperm parameters such as density and volume varied widely depending on collection time. The highest numbers of spermatozoa per individual were collected 15–42h post-CPE treatment in (A) and at 42h post-CPE treatment in (B) (85±4% and 64±5% of total spermatozoa count, respectively). Median percent motility in spermatozoa before cryopreservation was 26–100% and 5–67% post-thaw. Fertilization rates obtained with frozen/thawed spermatozoa were 13–76% (median value). A significant increase in spermatozoa motility parameters and fertilizing ability at the second collection on each day was observed. Sequential stripping and spermatozoa cryopreservation in combination could improve the efficiency of sturgeon aquaculture.

Waste production and valorization in an integrated aquaponic system with bester and lettuce

The purpose of this study was to characterize the wastewater effluent emerging from sturgeon aquaculture and to evaluate its potential for hydroponic lettuce production. Bester sturgeon and Lactuca sativa were used to test both nitrogen excretion and uptake in an aquaponic system under two hydraulic regimes. In the end of the experiment, fish growth performance, lettuce yields and nutrient retention were assessed. Higher ammonia excretion for sturgeons held in higher hydraulic retention time (HRT) was found. Similarly, lettuce registered greater amount of both biomass and yield in lower flow treatment. In terms of wastewater treatment efficiency, lower nitrate removal rate and higher total ammonia nitrogen (TAN) removal rate occurred in high flow rate treatments. Key words : Phytoremediation, recirculating aquaculture, raft hydroponics, Lactuca sativa .

Management approaches and aquaculture of sturgeons in the Lower Danube region countries

Summary This paper presents the status and trends in management of sturgeon species and the development of sturgeon aquaculture in the Lower Danube countries: Romania, Bulgaria, Serbia, Ukraine and Moldova. Sturgeon fishery moratoria and aquaculture development represent first steps in the Lower Danube countries to combat extirpation. Supportive stocking was used as a compensation for the impact of sturgeon fishery and dam construction, but these efforts unfortunately lacked adequate cooperation and coordination between and among region countries. Unsolved problems remain, such as the presence of illegal sturgeon fishery, water pollution, habitat destruction and fragmentation. Construction of fish passes and habitat restoration project developments are two key issues that have yet to be tackled in the Lower Danube region.

EST dataset of pituitary and identification of somatolactin and novel genes in Chinese sturgeon, Acipenser sinensis

Chinese sturgeon (Acipenser sinensis) is a rare and endangered species and also an important resource for the sturgeon aquaculture industry, however, a few genes have been identified in this species. We report here construction of a pituitary cDNA library from a 24years old female Chinese sturgeon just after its spawning, and obtained 2,025 ESTs from the library. 885 unique sequences were identified, which were categorized into 12 functional groups. More than half of the unique sequences (57%) do not match with annotated sequences in the public databases. Three of these novel genes were further identified. Notably, a full-length of cDNA (1,143bp) encoding somatolactin of 232 amino acids was identified. Phylogenetic analysis showed 97% amino acid identity with White sturgeon somatolactin. RT-PCR analysis indicated that the somatolactin mRNA was only detected in pituitary. Pituitary-specific expression of the somatolactin suggested that the protein may play important physiological functions in pituitary-endocrine system of the Chinese sturgeon.

Sturgeon aquaculture in China: progress, strategies and prospects assessed on the basis of nation-wide surveys (2007-2009)

The authors examined the current status of sturgeon aquaculture in China, including its geographic distribution, an account on farmed species, overall production trends, state of controlled reproduction, seedling output and export. The study is based on a nationwide survey of 125 farms undertaken July and August 2009 together with data from previous studies. The census shows that: (i) the main provinces in increasing order of production are Sichuan (including Chongqing), Beijing, Hubei, Shandong and Hunan, (ii) Acipenser baerii, (and its hybrids) and A. schrenckii are the dominant cultured species, accounting for 95% of the total production, (iii) the production of farmed sturgeon has experienced a steady increase, from 17 424 t in 2006 to 21 000 t in 2009, (iv) the total reserves of captive stocks have continuously increased, reaching at present an estimated 1.22 million individuals, (v) the total supply of fertilized eggs or larvae from farmed broodstocks in China has gone up during the past 3 years, and can now basically meet the domestic demand for farming, while the number of seedlings obtained from the wild and imported from other countries gradually declined, and (vi) since 2006, China has started to export farmed caviar and the exports have been increasing year by year, meanwhile, the number of caviar processing factories has also increased. Moreover, other value-added products derived from farmed sturgeon (e.g. medical and health products, cosmetics, leather etc.) appeared in recent years on China markets. Corresponding to the sturgeon aquaculture development in China, some additional future aquaculture strategies are discussed: (i) make full use of the resources, (ii) strengthen management strategies and upgrade the culture techniques, (iii) develop and implement labeling systems for good quality control, (iv) foster deep-processing (value added products) in sturgeon farming to widen market options, (v) enhance extensive genetic studies and research on gynogenesis and cryopreservation of gametes for better resource management, (vi) improve the knowledge on early sex-differentiation in sturgeon, and (vii) prepare standards for management of sustainable sturgeon aquaculture. Considering the current progress of sturgeon aquaculture, the prospects of future sturgeon farming are assessed: (i) there will be a potential for considerable aquaculture to serve the caviar market, and farmed caviar may replace wild products, (ii) product diversification will increase and target for export markets, (iii) hatchery operations to produce juveniles from controlled reproduction will completely replace supply from wild and imported resources, and (iv) an industry chain will be gradually established to ensure sustainable sturgeon aquaculture production in China.

Acclimation to farm conditions of wild caught sturgeon species as by-catch from the North-West Turkish Black Sea coasts

Fisheries Faculty, Mugla University,Ko¨tekli, Mugla, TurkeySummaryThe objective of this study was to investigate the acclimationcondition for by-catch sturgeons taken to farming facilities,monitoring, condition factor and mortality rates of threedifferent sturgeon species (Huso huso, Linnaeus 1758;Acipenser stellatus, Pallas 1771; Acipenser gueldenstaedtii,Brand& Ratzeberk 1758) which were caught along the BlackSea coasts. A total of nine individuals from by-catch of twodifferent sites were used. First site is the mouth of SakaryaRiver (41 07¢N; 30 38¢E; Yenimahalle) which flows to theBlack Sea, and the second was side of Istanbul Bosphorus(41 11¢N; 29 07¢E; Anadolukavagi) in the Black Sea. Theseindividuals were transfered from the catching area to theland by sustenance tank with marine water. Tests to adjustfish from live feed to manufactured feed under captiveconditions were also undertaken. Live food wet feed andmanufactured feed were used in this acclimation experiment.As a live feed tubifex food and earthern worms, as a wet feedchicken liver and minced white meat and as a manufacturedand sturgeon feed were used. Five individuals from threespecies were adapted to the farm conditions and manufac-tured feed in different days. The most sensitive sturgeon wasobserved stellat sturgeon, beluga and Russian sturgeon,respectively.IntroductionSturgeons (Acipenseriformes) are one of the most ancientgroup of the Osteichthyes with 27 species distributed in thetemperate waters of the Northen Hemisphere (Birnstein, 1993).The Black Sea inhabite (Huso and Acipenser) which wereBeluga (Huso huso), sturgeon (Acipenser sturio), Russiansturgeon (Acipenser gueldenstadtii), Stellate sturgeon or Sev-ruga (Acipenser stellatus), Sterlet (Acipenser ruthenus), Ship(Acipenser nudiventris) (Memis, 2007).Environmental pressures, such as water pollution, damconstruction and development of adjacent watersheds forirrigation proposes, which have been responsible for the loss ofspawning grounds, has declined populations and their diverstyis currently threatened due to human influences (Wirgin et al.,1997; Pourkazemi et al., 1999; Vasilev, 1999; Gisbert andWilliot, 2002; Rosenthal et al., 2006).As a result of these declines, all sturgeon species worldwidewere included in Appendix II of the Convention on theInternational Trade of Endangered Species of Wild Fauna andFlora (CITES) regulations on 1 April 1998. This provided aregulatory mechanism for import and export of sturgeon andtheir products helping to control the illegal caviar trade and itsdetriment to wild populations (Mohler, 2003). Turkey also wassigned this convention in 1998. From this date catching of allsturgeon species in Black Sea are forbidden by Ministry ofAgriculture and Rural Affair.The first experiment of controlled propagation of sturgeonwas carried out with 1869 A. ruthenus eggs in 1869. Insubsequent years, insemination and incubation were alsoperformed for some other sturgeon species (Dettlaff et al.,1993).Sturgeon aquaculture can be the only solution to theconservation of wild populations through restocking and byproviding a consistent supply without exploiting wild popula-tions. The main species used in aquaculture productionworldwide are white sturgeon (A. transmontanus), Siberian(A. baeri), Russian sturgeon (A. gueldenstadtii), sterlet(A. ruthenus) and hybrid called bester (beluga female x sterletmale) (Mims et al., 2002).There was six sturgeon species in the Black Sea region ofTurkey. But recently, only three species (A. gueldenstadtii,A. steallatus and H. huso) are still occurring occesionally onsouthern Black Sea coastline. The aim of this study is caught asby-catch different species of sturgeons from Black Sea andIstanbul Bosphorus mouth were adapted to aquaculture_conditions for evaluation as future broodstock management.Materials and methodsIn this study nine specimens of three species (Huso huso,Acipenser stellatus, and Acipenser gueldenstaedtii) were usedfor application to culture conditions in order to built graduallyan initial broodstock. These specimens were from Black Sea(41 07¢N; 30 38¢E) by-catches and from those of the IstanbulBosphorus (41 11¢N; 29 07¢E). All by-catches were transferredto Istanbul University Sapanca Inland Fish AquacultureResearch and Applied Station (SIFARAS) in a 150 L tankusing water from the catch area. Two locations were about 70and 120 km distances from the culture site. Catching locationsand biometric datas of sturgeon were recorded. Every fishwere tagged and named as Russian sturgeon (G1, G2, G3),Stellate sturgeon (S1, S2, S3, S4, S5) and Beluga sturgeon (H1)(Table 2).

Importance of environmental endocrinology in fisheries management and aquaculture of sturgeons

Less is known about the reproductive endocrinology of sturgeons compared to modern teleosts. However, tools to assess the reproductive endocrinology and effects of environmental factors on reproduction do exist. This review utilizes case studies to describe the parameters involved in environmental endocrinology and the management and recovery efforts for the phylogenetically ancient sturgeon and paddlefish (Clade Chondrostei). Specifically, we discuss the use of environmental endocrinology to determine sex and stage of maturity and identify oviposition on spawning grounds, the importance of understanding endocrine disruption pathways, the challenges and benefits of assessing stress in wild populations of sturgeon, and three major physiological events in the reproductive development of farmed sturgeon understanding of which appears to be crucial for improving sturgeon aquaculture.

Molecular characterization and expression pattern of three zona pellucida 3 genes in the Chinese sturgeon, Acipenser sinensis

Chinese sturgeon (Acipenser sinensis) is a rare and endangered species and also an important resource for the sturgeon aquaculture industry. SMART cDNAs were synthesized from the ovary of A. sinensis, and the full-length cDNAs of three zona pellucida glycoprotein 3 genes (the new gene named AsZP3) were cloned and sequenced. AsZP3.1, AsZP3.2, and AsZP3.3 were 1,388 base pairs (bp), 1,288, and 1,290 bp in length, respectively, and they could be translated into proteins with 440, 394, and 398 amino acids, respectively. High level of amino acids sequence identity was seen between AsZP3.2 and AsZP3.3 (about 82%), but they share low identity with AsZP3.1 (26 and 23%, respectively). The AsZP3.1 has 42-50% amino acids sequence identity values with other fish and lower values with higher vertebrates (38%); AsZP3.2 and AsZP3.3 shared about 30-44% sequence identity with higher vertebrates and other fish. RT-PCR analysis indicated that AsZP3.1 displayed a wide tissue distribution at the mRNA levels including liver, kidney, spleen, heart, and ovary, but AsZP3.2 and AsZP3.3 mRNAs were expressed exclusively in the gonad. All three AsZP3 mRNAs were not detected during embryogenesis and early larval development; furthermore, they were not detected in the gonads of 1- and 2-year-old Chinese sturgeons. All three AsZP3 mRNAs were detected in the testes of 3-year-old males and in the ovaries of 4- and 5-year-old female Chinese sturgeons.

Sturgeon aquaculture in China: status of current difficulties as well as future strategies based on 2002–2006/2007 surveys in eleven provinces

Summary A nationwide survey in July and August 2007 employed a representative sample of Chinese sturgeon farms from 2002–2006/2007, including data from previous surveys and official statistics dating back to 1998, showing that the development of China’s sturgeon aquaculture has progressed steadily in the past few years. Acipenser baerii and Amur hybrids (Acipenser schrenckii × Huso dauricus) have become the dominant cultured species, accounting for 80% of total production. Production centers moved from the southeastern coast towards the midwestern inland provinces, where cold freshwater resources are available in abundance. The paper presents production trends as well as the price structure for commercial fish/meat and juveniles in the various provinces and also considers import and export data for products, fertilized eggs and fingerlings. Results show that: (i) production of juveniles in hatcheries has risen only slightly during the survey period; (ii) the number of larvae obtained from the wild gradually declines each year; (iii) the price for commercial fish/meat drastically declined between 1998 to 2002, but remained stable from 2002 to 2007; and (iv) total production from the 83 surveyed farms was almost stable from 2002 to 2007. Major problems influencing sustainable development of sturgeon aquaculture were identified, including: (i) insufficient domestic supply of larvae and the ban for commercial use of A. sinensis; (ii) disorganized hybridization; (iii) the potential threat to the genetics of natural stocks in the Yangtze River; (iv) diseases originating from environmental pollution and poor-quality fish feed; (v) limited domestic markets; (vi) low volume of sturgeon export due to lack of intensive processing; and (vii) lack of organizational structure in the industry.

On the history of fish husbandry of Siberian sturgeon Acipenser baerii from the Lena River for acclimatization and commercial cultivation

This paper provides a brief description of the history of home sturgeon aquaculture and the assessment of the role in its development of Russian scientists, Lebedev, in particular, whose ideas served as the scientific basis of the introduction of Siberian sturgeon Acipenser baerii in culture. The main stages of works on obtaining fertilized eggs of sturgeon under field conditions, their transportation from the spawning grounds to fish farms, as well as the elaboration of biotechniques of the introduction in culture of the species are described. Principal causes of the failure of acclimatization works with Siberian sturgeon are analyzed.

Molecular and expression characterization of two somatostatin genes in the Chinese sturgeon, Acipenser sinensis

Chinese sturgeon ( Acipenser sinensis) is a rare and endangered species and also an important resource for the sturgeon aquaculture industry. SMART cDNA was synthesized from the hypothalamus of Chinese sturgeon, and the full-length cDNAs of two somatostatin ( SS) genes were cloned and sequenced. The first cDNA ( AsSS1) encodes a 116-amino acid protein that contains the SS 14 sequence at its C-terminal extremity. AsSS1 shows high identity to that of human and other vertebrates. The second cDNA ( AsSS2) encodes a 111-amino acid protein that contains the somatostatin variant [Pro 2]-SS 14 at its C-terminal extremity. Both the two SS mRNAs were expressed in brain and pituitary with different mRNA levels. But in peripheral tissues, AsSS2 was more widely distributed than AsSS1. High mRNA levels of AsSS2 were found in liver, kidney and heart, while low mRNA levels of AsSS2 were also detected in ovary. Throughout embryogenesis and early larval development only AsSS2 mRNAs were detected. Furthermore, in the hypothalamus of one to five year-old Chinese sturgeon, AsSS2 but not AsSS1 maintained stable expression. The mRNA distribution suggests that the Chinese sturgeon AsSS2 products play important physiological functions in adult fish as well as in cell growth and organ differentiation in embryo and larva development.

Molecular characterization of Chinese sturgeon gonadotropins and cellular distribution in pituitaries of mature and immature individuals

Chinese sturgeon ( Acipenser sinensis) is a rare and endangered species, and also an important resource for the sturgeon aquaculture industry. To understand molecular characterization of Chinese sturgeon gonadotropins (GTHs), we cloned the full-length cDNAs of gonadotropin subunits common α (GTH-α), follicle-stimulating hormone (FSH) and luteinizing hormone (LH) from a pituitary cDNA library of mature female. Two subtypes of GTH-α were identified. The nucleotide sequences of A. sinensis common α I ( AsGTH-α I), common α II ( AsGTH-α II), FSHβ ( AsFSHβ) and LHβ ( AsLHβ) subunit cDNAs are 345, 363, 387 and 414 bp in length, and encode mature peptides of 115, 121, 129 and 138 aa, respectively. Then, three polyclonal antibodies were prepared from the in vitro expressed AsGTH-α I, AsFSHβ and AsLHβ mature proteins, respectively. Significant expression differences were revealed between immature and mature sturgeon pituitaries. Western blot detection and immunofluoresence localization revealed the existence of three-gonadotropin subunits ( AsGTH-α, AsFSHβ and AsLHβ) in mature sturgeon pituitaries, but only AsFSHβ was detected in immature individual pituitaries during early stages in the sturgeon life, and obvious difference was observed between males and females. In males, AsFSHβ was expressed in 4-year-old individuals, whereas in females, AsFSHβ was just expressed in 5-year-old individuals.

Sturgeon Aquaculture - Specialized Techniques Determining the Stage of Sexual Maturity in Female Sturgeon for Artificial Spawning The Egg Maturation Assay

FA-154, a 4-page illustrated fact sheet by Frank A. Chapman and Joel P. Van Eenennaam, describes a biological test to determine if sturgeon eggs are in the stage of final maturation — the principle behind the test, materials needed, and protocol. Published by the UF Department of Fisheries and Aquatic Sciences, December 2007. FA154/FA154: Sturgeon Aquaculture—Specialized Techniques: Determining the Stage of Sexual Maturity in Female Sturgeon for Artificial Spawning: The Egg Maturation Assay (ufl.edu)