Warth, Peter; Hilton, Eric J; Naumann, Benjamin; Olsson, Lennart; Konstantinidis, Peter
The head is considered the major novelty of the vertebrates and directly linked to their evolutionary success. Its form and development as well as its function, for example in feeding, is of major interest for evolutionary biologists. In this study, we describe the skeletal development of the cranium and pectoral girdle in Siberian (Acipenser baerii) and Russian sturgeon (A. gueldenstaedtii), two species that are commonly farmed in aquaculture and increasingly important in developmental studies. This study comprises the development of the neuro-, viscero- and dermatocranium and the dermal and chondral components of the pectoral girdle, from first condensation of chondrocytes in prehatchlings to the early juvenile stage and reveals a clear pattern in formation. The otic capsules, the parachordal cartilages, and the trabeculae cranii are the first centers of chondrification, at 8.4mm TL. These are followed by the mandibular, then the hyoid, and later the branchial arches. Teeth form early on the dentary, dermopalatine, and palatopterygoid, and then appear later in the buccal cavity as dorsal and ventral toothplates. With ongoing chondrification in the neurocranium a capsule around the brain and a strong rostrum are formed. Dermal ossifications start to form before closure of the dorsal neurocranial fenestrae. Perichondral ossification of cartilage bones occurs much later in ontogeny. Our results contribute data bearing on the homology of elements such as the lateral rostral canal bone that we regard homologous to the antorbital of other actinopterygians based on its sequence of formation, position and form. We further raise doubts on the homology of the posterior ceratobranchial among Actinopteri based on the formation of the hyoid arch elements. We also investigate the basibranchials and the closely associated unidentified gill-arch elements and show that they are not homologous. J. Morphol. 278:418-442, 2017. © 2017 Wiley Periodicals, Inc.
Complete mitochondrial genome sequences of Atlantic sturgeon, Acipenser oxyrinchus oxyrinchus, Gulf sturgeon, A. o. desotoi and European sturgeon A. sturio (Acipenseriformes: Acipenseridae) obtained through next generation sequencing.
Popović, Danijela; Baca, Mateusz; Panagiotopoulou, Hanna
Complete mitochondrial genome sequences of European sturgeon and two subspecies of the North American, Atlantic and Gulf sturgeons were determined using MiSeq Illumina technology. All three genomes show typical vertebrate organization. They possess 22 tRNA genes, 13 protein-coding genes, 2 rRNA (ribosomal RNA) genes and a non-coding control region. Excluding ND6, all protein-coding genes are on the heavy strand. The whole mitogenome sequences have been deposited in GenBank under accession numbers KP997216-KP997218.
Horvath, A.; Wayman, W.R.; Dean, J.C.; Urbanyi, B.; Tiersch, T.R.; Mims, S.D.; Johnson, D.; Jenkins, J.A.
Populations of sturgeon across the globe are threatened due to unregulated harvest and habitat loss, and the status varies among species across North America. Ready access to viable and functional sperm would contribute to recovery programmes for these species. In this study, we examined the motility, viability (cell membrane integrity) of cryopreserved sperm from three North American acipenseriform species and fertilizing capacity. Milt samples were collected from captive shortnose sturgeon (Acipenser brevirostrum), wild paddlefish (Polyodon spathula) and pallid sturgeon (Scaphirhynchus albus) and cryopreserved using combinations of Modified Tsvetkova's (MT) extender, Original Tsvetkova's extender, and modified Hanks' balanced salt solution, along with the cryoprotectants methanol (MeOH) or dimethyl sulfoxide (DMSO). A dual-staining technique using the fluorescent stains SYBR-14 and propidium iodide was employed with flow cytometry to determine the percentages of spermatozoa that were viable by virtue of having intact membranes. The percentage of viable spermatozoa ranged from 5% to 12% in shortnose sturgeon, 30-59% in paddlefish, and 44-58% in pallid sturgeon. In the first experiment with shortnose sturgeon sperm, methanol allowed for higher values for dependent variables than did DMSO, and sperm viability generally correlated with post-thaw motility. However, fertilization rate, neurulation, or hatching rates were independent from these factors. In the second experiment with shortnose sturgeon, 5% MeOH combined with MT yielded higher values for all parameters tested than the other combinations: viability was correlated with motility, fertilization rate, and hatching rate. Overall, viability and post-thaw motility was not affected by the use of hyperosmotic extenders (OT) or cryoprotectants (DMSO), but their use decreased fertilization percentages. For paddlefish sperm (experiment 3), MT combined with 10% MeOH was clearly a good choice for cryopreservation
Rzepkowska, Malgorzata; Ostaszewska, Teresa; Gibala, Monika; Roszko, Marek Lukasz
Among sturgeons, the occurrence of individuals with gonads containing both testis and ovary components is considered pathological, and such fish are described as intersex individuals or intersexes. Intersexes are observed in both wild and cultured populations of sturgeon, usually at low frequencies. In the present study, intersex Russian (Acipenser gueldenstaedtii) and Siberian (Acipenser baerii) sturgeons constituted 30% of the studied populations. Macroscopically, intersex gonads were recognizable from 500 days posthatching (dph). Initially, gonads with predominantly male characteristics (testis-ova) were observed, but in older fish gonads with predominantly female traits (ova-testis) were more frequent. Using microscopic analysis, intersex gonads were discernible by 130-200 dph. Observations of intersex germinal epithelium development and analysis of sex distribution in the study populations indicated that feminization was occurring. Histological analysis revealed that differentiation of the germinal epithelium in such gonads was accompanied by various morphological alterations (transformations) that were described using quantitative and localization criteria. The most common type of transformations, massive subepithelial transformations, was manifested by the presence of abundant female germinal tissue located under the gonad surface epithelium in the developing testis. These transformations were identified in the early development stage (100-200 dph). In this type of transformation, differentiation of female germinal tissue at the gonad surface and male tissue at the mesorchium/mesovarium resulted in complete formation of both male and female germinal epithelia within the same gonad.
Dinçer, Barbaros; Ekinci, Arife Pınar; Akyüz, Gülay; Kurtoğlu, İlker Zeki
An α-carbonic anhydrase (CA, EC 220.127.116.11) was purified and characterized kinetically from gill of Acipenser gueldenstaedtii as an endangered sturgeon species. The carbonic anhydrase was purified 66-folds with yield 20.7% by Sepharose-4B-l-tyrosine-sulfanilamide affinity column and the specific activity was determined as 222.2 EU/mg protein. Km and Vmax kinetic values for gill carbonic anhydrase were calculated by a Lineweaver-Burk graph using p-nitrophenol acetate (p-NPA) as a substrate, and was defined as 2.5 mM and 5 × 10(6 )μM/min, respectively. It was observed that CA from the sturgeon gill in the presence of the sulfanilamide and acetazolamide as an inhibitor had very low IC50 values such as 13.0 and 0.1 μM, respectively. In addition, it was determined that the enzyme was inhibited by Fe(2+,) Co(2+,) Ni(2+), and Zn(2+)-Ba(2+) with the IC50 values of 0.2, 1.7, 1.2, and 1.1 mM, respectively.
Moravec, František; Kuchta, Roman
Two new nematode species are described from the paddlefish Polyodon spathula (Walbaum) (Polyodontidae, Acipenseriformes) from the Mississippi River drainage, United States, based on specimens previously deposited in the U.S. National Parasite Collection. Those specimens were Camallanus polyodontis n. sp. (Camallanidae) from the host (site of infection not given) collected in the Yellowstone River, Montana in 1974 and Syngnathinema chitwoodi n. sp. (Daniconematidae) from the body cavity of fish collected in Mississippi in 1926. Camallanus polyodontis (male and female) is mainly characterized by the presence of a conspicuously large, oval, sclerotized formation at the base of tridents on the buccal capsule, by which it distinctly differs from all congeners. It also differs from other North American species of the genus by additional features such as the body size, the length of spicules, or the length of the female tail. Syngnathinema chitwoodi (a single subgravid female) differs from the only other congener, Syngnathinema californiense Moravec, Spangenberg and Frasca, 2001, a parasite of the circulatory system of the pipefish in California and British Columbia, mainly in that the posterior end of the muscular esophagus is not submerged into the anterior end of the glandular esophagus. Previous reports of Camallanus oxycephalus Ward and Magath, 1917 in P. spathula may be misidentifications of C. polyodontis.
Kuz'min, E V
Creatine kinase (E.C. 18.104.22.168) was examined in stellate sturgeon Acipenser stellatus Pallas, Russian sturgeon A. gueldenstaedtii Brandt, European sterlet A. ruthenus L., Siberian sterlet A. ruthenus marsiglii Brandt, and great sturgeon (beluga) Huso huso L., using polyacrylamide gel electrophoresis. Two loci for creatine kinase were identified: CK-A* in white skeletal muscle and CK-C* in stomach wall muscle. Most species proved to be monomorphic at the CK-A* locus, showing the same phenotype represented by a single band. Heterogeneity and polymorphism in creatine kinase, determined by the CK-A* locus, were found only in Russian sturgeon. Based on the results of densitometric analysis of band staining intensity, we have advanced a hypothesis that synthesis of subunits of the CK-A* product in this species was controlled by eight genes. However, the genotype frequencies in the sample were significantly different from those theoretically expected upon free and independent gene recombination. The results of this study support the hypothesis on the absence of heterodimeric creatine kinase molecules in the skeletal muscle of Russian sturgeon. Locus CK-C* in sterlet was revealed as a single, intensely stained, rapidly migrating fraction, whereas in Russian sturgeon, the enzyme activity in this zone was very weak. No creatine kinase was found in liver, kidneys, spleen, heart, and intestine mucous tunic.
Dillman, Casey B; Hilton, Eric J
Acipenseriformes hold an important place in the evolutionary history of bony fishes. Given their phylogenetic position as extant basal Actinopterygii, it is generally held that a thorough understanding of their morphology will greatly contribute to the knowledge of the evolutionary history and the origin of diversity for the major osteichthyan clades. To this end, we examined comparative developmental series from the pectoral girdle in Acipenser fulvescens, A. medirostris, A. transmontanus, and Scaphirhynchus albus to document, describe, and compare ontogenetic and allometric differences in the pectoral girdle. We find, not surprisingly, broad congruence between taxa in the basic pattern of development of the dermal and chondral elements of the pectoral girdle. However, we also find clear differences in the details of structure and development among the species examined in the dermal elements, including the clavicle, cleithrum, supracleithrum, posttemporal, and pectoral-fin spine. We also find differences in the internal fin elements such as the distal radials as well as in the number of fin rays and their association with the propterygium. Further, there are clear ontogenetic differences during development of the dermal and chondral elements in these species and allometric variation in the pectoral-fin spine. The characters highlighted provide a suite of elements for further examination in studies of the phylogeny of sturgeons. Determining the distribution of these characters in other sturgeons may aid in further resolution of phylogenetic relationships, and these data highlight the role that ontogenetic and comparative developmental studies provide in systematics.
Sergeev, Alexey A.
Russian ( Acipenser gueldenstaedtii), Persian ( A. persicus) and Siberian ( A. baerii) sturgeons are closely related ‘Ponto-Caspian’ species. Investigation of their population structure is an important problem, the solution of which determines measures for conservation of these species. According to previous studies, ‘baerii-like’ mitochondrial genotypes were found in the Caspian Sea among 35% of Russian sturgeon specimens, but were not found in Persian sturgeons. This confirms genetic isolation of the Persian sturgeon from the Russian sturgeon in the Caspian Sea. However, in order to clarify the relationships of these species it is necessary to analyze nuclear DNA markers. The amplified fragment length polymorphism (method) allows estimating interpopulation and interspecific genetic distances using nuclear DNA markers. In the present study, four samples were compared: Persian sturgeons from the South Caspian Sea, Russian sturgeons from the Caspian Sea and the Sea of Azov, and Siberian sturgeons from the Ob’ River, which are close to the latter two species, but are also clearly morphologically and genetically distinct from them. For the amplified fragment length polymorphism (AFLP) method, eight pairs of selective primers were used. The analysis revealed that the Siberian sturgeon has formed a separate branch from the overall Persian-Russian sturgeons cluster, which was an expected result. In addition, the results showed that the Caspian Russian sturgeon is closer to the Persian sturgeon from the Caspian Sea than to the Russian Sturgeon from the Sea of Azov. The present DNA marker data confirm that despite the genetic isolation of the Persian sturgeon from the Russian sturgeon in the Caspian Sea, the Persian sturgeon is a young species. PMID:28003882
Ciulli, S; Volpe, E; Sirri, R; Passalacqua, P L; Cesa Bianchi, F; Serratore, P; Mandrioli, L
Diseased outbreaks with high mortality in farmed sturgeon are a limiting factor to the success of this emerging aquaculture sector in Europe. Thorough investigations of outbreaks can determine the aetiological agents, identify important pathological and epidemiological pathways of infections and pave the way for effective control strategies. A thorough investigation of a mortality outbreak in Russian (Acipenser gueldenstaedtii) and Siberian (Acipenser baerii) sturgeons in Italy, demonstrated the primary involvement of a sturgeon nucleo-cytoplasmic large DNA virus (NCLDV). While, the taxonomy classification of this new virus is still uncertain, its involvement in sturgeon mortality outbreaks in Europe is, for the first time, fully investigated and described. Furthermore, the coinfection of bacteria such as motile Aeromonas spp. and Acinetobacter spp. was reported. Genetic characterisation showed the close relationship between the European sturgeon NCLDV with North American sturgeon NCLDVs. Similarly to the latter, the European sturgeon NCLDV persists in survivors. Furthermore, a systemic distribution of the European sturgeon NCLDV was evident in diseased A. baerii and A. gueldenstaedtii and in recovered A. gueldenstaedtii. These epidemiological and pathological findings will help in the identification of effective control strategies for sturgeon NCLDV infection, which afflicts an important and emerging European aquaculture sector.
Żelazowska, M; Jankowska, W; Plewniak, E; Rajek, U
Ovarian nests in the ovaries of sexually maturing Russian sturgeon Acipenser gueldenstaedtii and North American paddlefish Polyodon spathula were investigated. They comprised early previtellogenic, diplotene stage oocytes and somatic cells. In the nucleoplasm, these oocytes contained chromatin in the form of grains, threads and lampbrush chromosomes, primary nucleoli and multiple nucleoli. Two stages of oocytes in nests were distinguished by differences in the distribution of mitochondria with distorted cristae and lipid droplets in the ooplasm. These stages were as follows: pre-early stage 1 (PE 1) and early stage 1 (EP 1) previtellogenic oocytes. In PE 1 oocytes few mitochondria with distorted cristae and lipid droplets were distributed randomly. The ooplasm of PE 1 oocytes was not differentiated into homogeneous and granular compartments. In EP 1 oocytes, mitochondria with distorted cristae were more numerous and grouped in the vicinity of the nucleus, lipid droplets accumulated near these mitochondria. In the nucleoplasm of EP 1 oocytes several low electron-dense spherical bodies, possibly Cajal bodies, were present.
Chen, Yadong; Xia, Yongtao; Shao, Changwei; Han, Lei; Chen, Xuejie; Yu, Mengjun; Sha, Zhenxia
As the Russian sturgeon (Acipenser gueldenstaedtii) is an important food and is the main source of caviar, it is necessary to discover the genes associated with its sex differentiation. However, the complicated life and maturity cycles of the Russian sturgeon restrict the accurate identification of sex in early development. To generate a first look at specific sex-related genes, we sequenced the transcriptome of gonads in different development stages (1, 2, and 5 yr old stages) with next-generation RNA sequencing. We generated >60 million raw reads, and the filtered reads were assembled into 263,341 contigs, which produced 38,505 unigenes. Genes involved in signal transduction mechanisms were the most abundant, suggesting that development of sturgeon gonads is under control of signal transduction mechanisms. Differentially expressed gene analysis suggests that more genes for protein synthesis, cytochrome c oxidase subunits, and ribosomal proteins were expressed in female gonads than in male. Meanwhile, male gonads expressed more transposable element transposase, reverse transcriptase, and transposase-related genes than female. In total, 342, 782, and 7,845 genes were detected in intersex, male, and female transcriptomes, respectively. The female gonad expressed more genes than the male gonad, and more genes were involved in female gonadal development. Genes (sox9, foxl2) are differentially expressed in different sexes and may be important sex-related genes in Russian sturgeon. Sox9 genes are responsible for the development of male gonads and foxl2 for female gonads.
Background Non-tuberculous mycobacteria responsible for piscine mycobacteriosis usually produce visceral granulomas in both freshwater and marine species. In this study, the first occurrence of Mycobacterium chelonae associated with tumor-like lesions in the Russian sturgeon (Acipenser gueldenstaedtii) is reported. Fifteen sturgeons from an Italian fish farm showing skin and oral cauliflower-like masses were investigated by histopathology, bacterial culture and molecular analyses. Results A total of 20 masses different in size located in the mouth and in pectoral and caudal fins (characterized by abundant calcium deposits and by mild to moderate granulomatous inflammation) were observed with a significant different degree of histological severity. All internal organs of the fish were negative for mycobacteria, Ziehl-Neelsen was positive in only one of the oral masses, whereas bacterial and PCR analyses detected the presence of M. chelonae for almost all the skin and oral masses. Based on these results, a calcinosis of dystrophic origin associated with a chronic granulomatous inflammation was considered as a primary diagnosis consequent to tissue injury in areas susceptible to trauma. Conclusions We hypothesized that the occurrence of M. chelonae in farmed sturgeons was only a secondary event related to its presence in a stressful rearing environment and subsequent to a dystrophic calcinosis occurred in previously damaged tissues. PMID:24423126
Nelson, Troy C; Doukakis, Phaedra; Lindley, Steven T; Schreier, Andrea D; Hightower, Joseph E; Hildebrand, Larry R; Whitlock, Rebecca E; Webb, Molly A H
Worldwide, sturgeons (Acipenseridae) are among the most endangered fishes due to habitat degradation, overfishing, and inherent life history characteristics (long life span, late maturation, and infrequent spawning). As most sturgeons are anadromous, a considerable portion of their life history occurs in estuarine and marine environments where they may encounter unique threats (e.g., interception in non-target fisheries). Of the 16 marine-oriented species, 12 are designated as Critically Endangered by the IUCN, and these include species commercially harvested. We review important research tools and techniques (tagging, electronic tagging, genetics, microchemistry, observatory) and discuss the comparative utility of these techniques to investigate movements, migrations, and life-history characteristics of sturgeons. Examples are provided regarding what the applications have revealed regarding movement and migration and how this information can be used for conservation and management. Through studies that include Gulf (Acipenser oxyrinchus desotoi) and Green Sturgeon (A. medirostris), we illustrate what is known about well-studied species and then explore lesser-studied species. A more complete picture of migration is available for North American sturgeon species, while European and Asian species, which are among the most endangered sturgeons, are less understood. We put forth recommendations that encourage the support of stewardship initiatives to build awareness and provide key information for population assessment and monitoring.
Nelson, Troy C.; Doukakis, Phaedra; Lindley, Steven T.; Schreier, Andrea D.; Hightower, Joseph E.; Hildebrand, Larry R.; Whitlock, Rebecca E.; Webb, Molly A. H.
Worldwide, sturgeons (Acipenseridae) are among the most endangered fishes due to habitat degradation, overfishing, and inherent life history characteristics (long life span, late maturation, and infrequent spawning). As most sturgeons are anadromous, a considerable portion of their life history occurs in estuarine and marine environments where they may encounter unique threats (e.g., interception in non-target fisheries). Of the 16 marine-oriented species, 12 are designated as Critically Endangered by the IUCN, and these include species commercially harvested. We review important research tools and techniques (tagging, electronic tagging, genetics, microchemistry, observatory) and discuss the comparative utility of these techniques to investigate movements, migrations, and life-history characteristics of sturgeons. Examples are provided regarding what the applications have revealed regarding movement and migration and how this information can be used for conservation and management. Through studies that include Gulf (Acipenser oxyrinchus desotoi) and Green Sturgeon (A. medirostris), we illustrate what is known about well-studied species and then explore lesser-studied species. A more complete picture of migration is available for North American sturgeon species, while European and Asian species, which are among the most endangered sturgeons, are less understood. We put forth recommendations that encourage the support of stewardship initiatives to build awareness and provide key information for population assessment and monitoring. PMID:23990959
Kynard, B.; Zhuang, P.; Zhang, L.; Zhang, T.; Zhang, Z.
We conducted laboratory experiments with Volga River Russian sturgeon, Acipenser gueldenstaedtii, to develop a conceptual model of early behavior. We daily observed fish from day-0 (embryos, first life interval after hatching) to day-29 feeding larvae for preference of bright habitat and cover, swimming distance above the bottom, up- and downstream movement, and diel activity. Hatchling embryos initiated a downstream migration, which suggests that predation risk of embryos at spawning sites is high. Migration peaked on days 0-5 and ceased on day 7 (8-day migration). Migrants preferred bright, open habitat and early migrants swam-up far above the bottom (maximum daily median, 140 cm) in a vertical swim tube. Post-migrant embryos did not prefer bright illumination but continued to prefer white substrate, increased use of cover habitat, and swam on the bottom. Larvae initiated feeding on day 10 after 170.6 cumulative temperature degree-days. Larvae did not migrate, weakly preferred bright illumination, preferred white substrate and open habitat, and swam near the bottom (daily median 5-78 cm). The lack of a strong preference by larvae for bright illumination suggests foraging relies more on olfaction than vision for locating prey. A short migration by embryos would disperse wild sturgeon from a spawning area, but larvae did not migrate, so a second later migration by juveniles disperses young sturgeon to the sea (2-step migration). Embryo and larva body color was light tan and tail color was black. The migration, behavior, and light body color of Russian sturgeon embryos was similar to species of Acipenser and Scaphirhynchus in North America and to Acipenser in Asia that migrate after hatching as embryos. The similarity in migration style and body color among species with diverse phylogenies likely reflects convergence for common adaptations across biogeographic regions. ?? 2002 Kluwer Academic Publishers.
Zelazowska, Monika; Kilarski, Wincenty; Bilinski, Szczepan M; Podder, Daniel D; Kloc, Malgorzata
The oocytes of many organisms, including frogs and fish, contain a distinct cytoplasmic organelle called the Balbiani body. Because of the scarcity of published information and the tremendous variability in the appearance, ultrastructure, and composition of Balbiani bodies between species, the function of the Balbiani body and its inter-species homology remain a mystery. In Xenopus laevis, the Balbiani body is known to play a role in transporting germ cell determinants and localized RNAs to the oocyte vegetal cortex. In fish, however, the molecular composition of the Balbiani body has not been studied to date, and its function remains completely unknown. We have studied the ultrastructure and molecular composition of previtellogenic oocytes of the sturgeon, Acipenser gueldenstaedtii, by using electron microscopy, in situ hybridization, and immunostaining. We have found that sturgeon oocytes contain two distinct zones of cytoplasm: homogeneous (organelle-free) and granular (organelle-rich). We have also found that the granular ooplasm, which we term the Balbiani cytoplasm, shares important homologies, in both ultrastructure and molecular composition, with Xenopus Balbiani bodies.
Background Evolution of sturgeons and paddlefishes (order Acipenseriformes) is inherently connected with polyploidization events which resulted in differentiation of ploidy levels and chromosome numbers of present acipenseriform species. Moreover, allopolyploidization as well as autopolyploidization seems to be an ongoing process in these fishes and individuals with abnormal ploidy levels were occasionally observed within sturgeon populations. Here, we reported occurrence of Siberian sturgeon (Acipenser baerii) male with abnormal ploidy level for this species, accessed its ploidy level and chromosome number and investigate its potential sterility or fertility in comparison with normal individuals of sterlet (A. ruthenus), Russian sturgeon (A. gueldenstaedtii) and Siberian sturgeon (A. baerii). Results Acipenser ruthenus possessed 120 chromosomes, exhibiting recent diploidy (2n), A. gueldenstaedtii and A. baerii had ~245 chromosomes representing recent tetraploidy (4n), and A. baerii male with abnormal ploidy level had ~ 368 chromosomes, indicating recent hexaploidy (6n). Genealogy assessed from the mtDNA control region did not reveal genome markers of other sturgeon species and this individual was supposed to originate from spontaneous 1.5 fold increment in number of chromosome sets with respect to the number most frequently found in nature for this species. Following hormone stimulation, the spontaneous hexaploid male produced normal sperm with ability for fertilization. Fertilization of A. baerii and A. gueldenstaedtii ova from normal 4n level females with sperm of the hexaploid male produced viable, non-malformed pentaploid (5n) progeny with a ploidy level intermediate to those of the parents. Conclusion This study firstly described occurrence of hexaploid individual of A. baerii and confirmed its autopolyploid origin. In addition to that, the first detailed evidence about fertility of spontaneous hexaploid sturgeon was provided. If 1.5 fold increment in
Pracheil, Brenda M.; Chakoumakos, Bryan C.; Feygenson, Mikhail; ...
The otoliths of modern fishes are most commonly comprised of the metastable aragonite polymorph of calcium carbonate (CaCO3); however, sturgeons have otoliths reportedly comprised of the least stable of the three most-common polymorphs, vaterite. In this study, we used neutron diffraction to characterize CaCO3 polymorph composition of lake sturgeon and paddlefish otoliths. Based on previous summaries of CaCO3 composition over fish evolutionary history, we hypothesized that sturgeon and paddlefish otoliths would have similar polymorph composition. We found that despite previous reports of sturgeon otoliths being comprised entirely of vaterite, that all otoliths we examined in this study also had amore » calcite fraction that ranged from 17.9+ 6.0 wt. % to 35.9 + 2.9 wt. %. We also conducted a grinding experiment that demonstrated that calcite fractions were due to biological variation and not an artifact of polymorph transformation during preparation. Our study provides the initial characterization of the polymorph composition of the otoliths of lake sturgeon, and paddlefish and also provides the first-ever report of otoliths of Acipenserids as having a calcite fraction.« less
Pracheil, Brenda M.; Chakoumakos, Bryan C.; Feygenson, Mikhail; Whitledge, Gregory W.; Koenigs, Ryan P.; Bruch, Ronald M.
The otoliths of modern fishes are most commonly comprised of the metastable aragonite polymorph of calcium carbonate (CaCO3); however, sturgeons have otoliths reportedly comprised of the least stable of the three most-common polymorphs, vaterite. In this study, we used neutron diffraction to characterize CaCO3 polymorph composition of lake sturgeon and paddlefish otoliths. Based on previous summaries of CaCO3 composition over fish evolutionary history, we hypothesized that sturgeon and paddlefish otoliths would have similar polymorph composition. We found that despite previous reports of sturgeon otoliths being comprised entirely of vaterite, that all otoliths we examined in this study also had a calcite fraction that ranged from 17.9+ 6.0 wt. % to 35.9 + 2.9 wt. %. We also conducted a grinding experiment that demonstrated that calcite fractions were due to biological variation and not an artifact of polymorph transformation during preparation. Our study provides the initial characterization of the polymorph composition of the otoliths of lake sturgeon, and paddlefish and also provides the first-ever report of otoliths of Acipenserids as having a calcite fraction.
Żelazowska, Monika; Fopp-Bayat, Dorota
Previtellogenic and vitellogenic oocytes in ovarian follicles from cultured Siberian sturgeon Acipenser baerii were examined. In previtellogenic oocytes, granular and homogeneous zones in the cytoplasm (the ooplasm) are distinguished. Material of nuclear origin, rough endoplasmic reticulum, Golgi complexes, complexes of mitochondria with cement and round bodies are numerous in the granular ooplasm. In vitellogenic oocytes, the ooplasm comprises three zones: perinuclear area, endoplasm and periplasm. The endoplasm contains yolk platelets, lipid droplets, and aggregations of mitochondria and granules immersed in amorphous material. In the nucleoplasm, lampbrush chromosomes, nucleoli, and two types of nuclear bodies are present. The first type of nuclear bodies is initially composed of fibrillar threads only. Their ultrastructure subsequently changes and they contain threads and medium electron dense material. The second type of nuclear bodies is only composed of electron dense particles. All nuclear bodies impregnate with silver, stain with propidium iodide, and are DAPI-negative. Their possible role is discussed. All oocytes are surrounded by follicular cells and a basal lamina which is covered by thecal cells. Egg envelopes are not present in previtellogenic oocytes. In vitellogenic oocytes, the plasma membrane (the oolemma) is covered by three envelopes: vitelline envelope, chorion, and extrachorion. Vitelline envelope comprises four sublayers: filamentous layer, trabecular layer 2 (t2), homogeneous layer, and trabecular layer 1 (t1). In the chorion, porous layer 1 and porous layer 2 are distinguished in most voluminous examined oocytes. Three micropylar cells that are necessary for the formation of micropyles are present between follicular cells at the animal hemisphere. J. Morphol. 278:50-61, 2017. ©© 2016 Wiley Periodicals,Inc.
Barmintseva, A E; Mugue, N S
The genetic polymorphism often sturgeon species that inhabit the territory of the Russian Federation (Russian sturgeon, Siberian sturgeon, Amur sturgeon, Sakhalin sturgeon, Persian sturgeon, ship sturgeon, starlet, stellate sturgeon, beluga, and kaluga) was examined at five microsatellite loci (Afug41, Afug51, An20, AoxD161, AoxD165) (in total, 3821 individuals). The examined loci were successfully amplified with the same primer set in all species tested and demonstrated a high level of variation. Alleles specific to different species have been identified, which allows them to be used to identify species of sturgeon and their food products. In addition, the possibility of identifying hybrid forms was demonstrated. The assignment test performed in the STRUCTURE software program showed a high probability of correctly assigning each individual to its species based on genotyping with five microsatellite loci examined (96-98%, on average). However, for Russian and Persian sturgeon, the rate of proper species assignment was considerably lower (75 and 84%, respectively).
Dudu, Andreea; Georgescu, Sergiu Emil; Costache, Marieta
Sturgeons (Order Acipenseriformes) represent an extremely valuable natural resource that is now facing depletion. In the current study we evaluate if the traditional classification in subspecies of Acipenser gueldenstaedtii, Acipenser stellatus and Huso huso, endemic to Ponto-Caspian region is sustained by molecular analysis and if these represent Evolutionary Significant Units (ESUs) that should be managed separately in conservation programs. To examine the classification of taxonomic entities we sequenced a fragment of the mitochondrial control region in case of three sturgeon species that inhabit the North-western of Black Sea and migrate for reproduction in the Lower Danube. Beside these sequences, we used previously published sequences from sturgeon individuals sampled in the Black Sea, Azov Sea and Caspian Sea. We determined the genetic diversity and genetic differentiation, conducted a Population Aggregation Analysis (PAA) and inferred an intraspecific molecular phylogeny and haplotype network. The results indicated a low level of genetic differentiation between the geographically designated subspecies and did not support a significant divergence or reciprocal monophyly between them. Our results confirm previous genetic studies with smaller samples sizes, but additional analyses including nuclear markers should be conducted for proper recommendations aiming at the development of conservation programs. PMID:25249783
Guerrero, Alejandro; Icardo, José M; Durán, Ana C; Gallego, Alejandro; Domezain, Alberto; Colvee, Elvira; Sans-Coma, Valentín
Previous work showed that in the adult sturgeon an intrapericardial, nonmyocardial segment is interposed between the conus arteriosus of the heart and the ventral aorta. The present report illustrates the ontogeny of this intermediate segment in Acipenser naccarii. The sample studied consisted of 178 alevins between 1 and 24 days posthatching. They were examined using light and electron microscopy. Our observations indicate that the entire cardiac outflow tract displays a myocardial character during early development. Between the fourth and sixth days posthatching, the distal portion of the cardiac outflow tract undergoes a phenotypical transition, from a myocardial to a smooth muscle-like phenotype. The length of this region with regard to the whole outflow tract increases only moderately during subsequent developmental stages, becoming more and more cellularized. The cells soon organize into a pattern that resembles that of the arterial wall. Elastin appears at this site by the seventh day posthatching. Therefore, two distinct components, proximal and distal, can be recognized from the fourth day posthatching in the cardiac outflow tract of A. naccarii. The proximal component is the conus arteriosus, characterized by its myocardial nature and the presence of endocardial cushions. The distal component transforms into the intrapericardial, nonmyocardial segment mentioned above, which is unequivocally of cardiac origin. We propose to designate this segment the "bulbus arteriosus" because it is morphogenetically equivalent to the bulbus arteriosus of teleosts. The present findings, together with data from the literature, point to the possibility that cells from the cardiac neural crest are involved in the phenotypical transition that takes place at the distal portion of the cardiac outflow tract, resulting in the appearance of the bulbus arteriosus. Moreover, they suggest that the cardiac outflow tract came to be formed by a bulbus arteriosus and a conus arteriosus from an early period of the vertebrate evolutionary story. Finally, we hypothesize that the embryonic truncus of birds and mammals is homologous to the bulbus arteriosus of fish.
Saito, Taiju; Psenicka, Martin
Primordial germ cells (PGCs) are the origin of all germ cells in developing embryos. In the sturgeon embryo, PGCs develop from the vegetal hemisphere, which mainly acts as an extraembryonic source of nutrition. Current methods for studying sturgeon PGCs require either killing the fish or using costly and time-consuming histological procedures. Here, we demonstrate that visualization of sterlet (Acipenser ruthenus>) PGCs in vivo is feasible by simply labeling the vegetal hemisphere with fluorescein isothiocyanate (FITC)-dextran. We injected FITC-dextrans, with molecular weights varying between 10 000 and 2 000 000, into the vegetal pole of 1- to 4-cell stage embryos. At the neurula to tail-bud developmental stages, FITC-positive PGC-like cells appeared ventrally around the developing tail bud in the experimental group that received a high-molecular-weight FITC-dextran. The highest average number of FITC-positive PGC-like cells was observed in embryos injected with FITC-dextran having a molecular weight of 500 000 (FD-500). The pattern of migration of the labeled cells was identical to that of PGCs, clearly indicating that the FITC-positive PGC-like cells were PGCs. Labeled vegetal cells, except for the PGCs, were digested and excreted before the embryos starting feeding. FITC-labeled PGCs were observed in the developing gonads of fish for at least 3 mo after injection. We also found that FD-500 could be used to visualize PGCs in other sturgeon species. To the best of our knowledge, this report is the first to demonstrate in any animal species that PGCs can be visualized in vivo for a long period by the injection of a simple reagent.
Bullard, Stephen A; Snyder, Scott D; Jensen, Kirsten; Overstreet, Robin M
Acipensericola petersoni n. gen., n. sp. (Digenea: Aporocotylidae) infects the heart of the American paddlefish Polyodon spathula (Walbaum, 1792) in the Mississippi Delta. It has robust, spike-like body spines arranged in ventrolateral transverse rows; a bowl-shaped anterior sucker centered on the mouth and having minute spines on the inner anteroventral surface only; a pharynx; an inverse U-shaped ceca extending to near the posterior body end; intercecal testes comprising a pre-ovarian testicular column plus a single testis posteriorly; an extensively lobed ovary located medially and immediately posterior to the testicular column; a spherical ootype that is intercecal and post-ovarian; a Laurer's canal; and a common genital pore. The new species is the first-named aporocotylid collected from a basal actinopterygian. It resembles the chondrichthyan aporocotylids Chimaerohemecus trondheimensis, Orchispirium heterovitellatum, and Hyperandrotrema cetorhini in having an inverse U-shaped ceca, but it is morphologically most similar to the anguilliform aporocotylid Paracardicoloides yamagutii in having that feature plus a comparable anterior sucker, a single testis posteriorly, an intertesticular ovary, and a common genital pore. Sequence data for the complete small subunit ribosomal DNA (18S) do not refute its membership within Aporocotylidae nor its affinity to 1 of those aforementioned aporocotylids: A. petersoni was basal to the few teleost aporocotylids analyzed, and C. trondheimensis was the only taxon basal to A. petersoni. We regard the specimens of Spirorchis sp. previously reported from the shortnose sturgeon Acipenser brevirostrum Lesueur, 1818 as congeneric with the new species.
The description and histopathology of Leptorhynchoides polycristatus n. sp. (Acanthocephala: Rhadinorhynchidae) from sturgeons, Acipenser spp. (Actinopterygii: Acipenseridae) in the Caspian Sea, Iran, with emendation of the generic diagnosis.
Amin, Omar M; Heckmann, Richard A; Halajian, Ali; El-Naggar, Atif M; Tavakol, Sareh
Of the three known species of Leptorhynchoides Kostylew 1924, two are reported from North American fishes: Leptorhynchoides aphredoderi Buckner and Buckner 1976 and Leptorhynchoides thecatus (Linton 1891) Kostylew 1924. The third species, Leptorhynchoides plagicephalus (Westrumb 1821) Kostylew 1924, is commonly found in the Caspian and Black Sea from at least four species of sturgeons including Acipenser stellatus Pallas 1771 and the Acipenser nudiventris Lovetzsky 1828 from which Leptorhynchoides polycristatus n. sp. was found. No taxonomic work has been reported for L. plagicephalus for the last 90 years. L. polycristatus n. sp. can be readily confused with L. plagicephalus because of many superficial similarities. Such similarities include the general shape of the trunk, proboscis, and organ systems. However, L. polycristatus is clearly distinguished from the other three species primarily by having (1) 19-20 proboscis hooks per row; (2) the shortest hooks are anterior and the longest at the middle; the opposite is true in L. plagicephalus; (3) with a cuticular collar enveloping the base of the proboscis hooks; (4) the surface of its proboscis hooks is ribbed; (5) with a broad collar of multiple rectangular cuticular crests encircling the anterior end of the trunk; this is the only member of Leptorhynchoides with such a structure; (6) with many large ovoid uninucleated cells in the subcuticular layer of the trunk; (7) with paired glandular clusters near the male reproductive opening and of suction cup-like sensory structures on the bursa; (8) with dorsoventral ligament across the vagina; (9) cement glands are in a cluster of eight arranged in two horizontal tiers of four glands each; (10) with female gonopore near terminal; (11) with structures interpreted as possible microtriches on the surface of the trunk; (12) and with thinner eggs. L. polycristatus caused extensive histopathological damage to host intestinal layers. The armed proboscis invades and attaches to the host mucosa causing villi compression and necrosis of the epithelial lining with subsequent hemorrhaging and granulocyte migration. No encapsulation of the acanthocephalan is visible, and the worm can migrate deep into the smooth muscle layers of the muscularis extrema. The presence of L. polycristatus in the lumen of the host intestine obstructs and damages the absorbing surface of the host affecting the nutritional potential. Dead, necrotic host epithelial tissue and remnants of villi and crypts are visible.
Kröger, Ronald H H; Gustafsson, Ola S E; Tuminaite, Inga
We have investigated the apparatus suspending the crystalline lens in the eyes of basal vertebrates. Data are presented for Holocephali (Chondrichthyes) and the actinopterygians Polypteriformes, Polyodontidae (Acipenseriformes), Lepisosteiformes, Amiiformes, and one teleost species, the banded archerfish (Toxotes jaculatrix). We also studied the optical properties of the lens in Polypteriformes, Lepisosteiformes, and the archerfish. Together with previously published results, our findings show that there are three basic types of lens suspension in vertebrates. These are i) a rotationally symmetric suspension (Petromyzontida, lampreys; Ceratodontiformes, lungfishes; Tetrapoda), ii) a suspension with a dorso-ventral axis of symmetry and a ventral papilla (all Chondrichthyes and Acipenseriformes), and iii) an asymmetric suspension with a ventral muscle and a varying number of ligaments (all Actinopterygii except for Acipenseriformes). Large eyes with presumably high spatial resolution have evolved in all groups. Multifocal lenses creating well-focused color images are also present in all groups studied. Stable and exact positioning of the lens, in many cases in combination with accommodative changes in lens position or shape, is achieved by all three types of lens suspension. It is somewhat surprising that lens suspensions are strikingly similar in Chondrichthyes and Acipenseriformes (Actinopterygii), while the suspension apparatus in Polypteriformes, usually being regarded as an actinopterygian group more basal than Acipenseriformes, are considerably more teleostean-like. This study completes a series of investigations on lens suspensions in nontetrapod vertebrates, covering all major groups except for the rare and highly derived coelacanths.
Haxton, Tim J.; Sulak, Kenneth J.; Hildebrand, L.
Sturgeon and paddlefish were historically the dominant large fishes in all major Northern American Rivers. All ten species have been affected the past 150 years from anthropogenic stressors such that they are considered imperiled by various jurisdictions. Status papers have been presented for each species as part of a special publication on North American Acipenseriformes. The objective of this paper is to provide a summary of the similarities and differences in life history, habitat requirements, and stressors among the species. Optimistically, this would facilitate better management of the order as a whole if management actions for one species can inform another, especially in situations where populations are too low to obtain pertinent information.
Ludwig, A; Belfiore, N M; Pitra, C; Svirsky, V; Jenneckens, I
Sturgeon (order Acipenserformes) provide an ideal taxonomic context for examination of genome duplication events. Multiple levels of ploidy exist among these fish. In a novel microsatellite approach, data from 962 fish from 20 sturgeon species were used for analysis of ploidy in sturgeon. Allele numbers in a sample of individuals were assessed at six microsatellite loci. Species with approximately 120 chromosomes are classified as functional diploid species, species with approximately 250 chromosomes as functional tetraploid species, and with approximately 500 chromosomes as functional octaploids. A molecular phylogeny of the sturgeon was determined on the basis of sequences of the entire mitochondrial cytochrome b gene. By mapping the estimated levels of ploidy on this proposed phylogeny we demonstrate that (I) polyploidization events independently occurred in the acipenseriform radiation; (II) the process of functional genome reduction is nearly finished in species with approximately 120 chromosomes and more active in species with approximately 250 chromosomes and approximately 500 chromosomes; and (III) species with approximately 250 and approximately 500 chromosomes arose more recently than those with approximately 120 chromosomes. These results suggest that gene silencing, chromosomal rearrangements, and transposition events played an important role in the acipenseriform genome formation. Furthermore, this phylogeny is broadly consistent with previous hypotheses but reveals a highly supported oceanic (Atlantic-Pacific) subdivision within the Acipenser/Huso complex. PMID:11454768
Gustafsson, Ola S E; Ekström, Peter; Kröger, Ronald H H
Crystalline lenses with multiple focal lengths in monochromatic light (multifocal lenses) are present in many vertebrate groups. These lenses compensate for chromatic aberration and create well-focused color images. Stabilization of the lens within the eye and the ability to adjust focus are further requirements for vision in high detail. We investigated the occurrence of multifocal lenses by photorefractometry and lens suspension structures by light and electron microscopy in sturgeons (Acipenseriformes, Chondrostei) as well as sharks and rays (Elasmobranchii, Chondrichthyes). Multifocal lenses were found in two more major vertebrate groups, the Chondrostei represented by Acipenseriformes and Chondrichthyes represented by Elasmobranchii. The lens suspension structures of sturgeons, sharks, and rays are more complex than described previously. The lens is suspended by many delicate suspensory fibers in association with a ventral papilla in all groups studied. The arrangements of the suspensory fibers are most similar between sturgeons and sharks. In rays, the lens is suspended by a smaller ventral papilla and the suspensory fibers are arranged more concentrically to the lens.
Balazik, Matthew T; Garman, Greg C; Fine, Michael L; Hager, Christian H; McIninch, Stephen P
Populations of sturgeon (Acipenseridae) have experienced global declines, and in some cases extirpation, during the past century. In the current era of climate change and over-harvesting of fishery resources, climate models, based on uncertain boundary conditions, are being used to predict future effects on the Earth's biota. A collection of approximately 400-year-old Atlantic sturgeon spines from a midden in colonial Jamestown, VA, USA, allowed us to compare the age structure and growth rate for a pre-industrial population during a 'mini-ice age' with samples collected from the modern population in the same reach of the James River. Compared with modern fish, the colonial population was characterized by larger and older individuals and exhibited significantly slower growth rates, which were comparable with modern populations at higher latitudes of North America. These results may relate to higher population densities and/or colder water temperatures during colonial times.
Leprévost, Amandine; AzaÏs, Thierry; Trichet, Michael; Sire, Jean-Yves
In order to improve our knowledge on the vertebral development, structure and mineralization in Acipenseriformes, we undertook a study in a growth series of reared Siberian sturgeons (Acipenser baerii) using in toto clear and stain specimens, histological and ultrastructural observations, X-ray micro-tomography, and solid state NMR analyses. Scutes were also studied to compare the tissue structure and mineralization of endoskeletal and dermal skeletal elements. This study completes and clarifies previous investigations on vertebral development and architecture in sturgeons, and brings original data on the structure of (i) the perichondral bone that is progressively deposited around the vertebral elements during ontogeny, (ii) the typical cartilage composing these elements, and (iii) the scutes. In addition we provide data on the mineralization process, on the nature of the bone mineral phase, and on the growth dynamics of the vertebral elements. Anat Rec, 300:437-449, 2017. © 2016 Wiley Periodicals, Inc.
Eichelberger, Jennifer S.; Braaten, P. J.; Fuller, D. B.; Krampe, Matthew S.; Heist, Edward J.
Spawning of the federally endangered Pallid Sturgeon Scaphirhynchus albus is known to occur in the upper Missouri River basin, but progeny from natural reproductive events have not been observed and recruitment to juvenile or adult life stages has not been documented in recent decades. Identification of Pallid Sturgeon progeny is confounded by the fact that Shovelnose Sturgeon S. platorynchus occurs throughout the entire range of Pallid Sturgeon and the two species are essentially indistinguishable (morphometrically and meristically) during early life stages. Moreover, free embryos of sympatric Paddlefish Polyodon spathula are very similar to the two sturgeon species. In this study, three single-nucleotide polymorphism (SNP) assays were employed to screen acipenseriform free embryos and larvae collected from the upper Missouri River basin in 2011, 2012, and 2013. A mitochondrial DNA SNP discriminates Paddlefish from sturgeon, and specific multilocus genotypes at two nuclear DNA SNPs occurred in 98.9% of wild adult Pallid Sturgeon but only in 3% of Shovelnose Sturgeon sampled in the upper Missouri River. Individuals identified as potential Pallid Sturgeon based on SNP genotypes were further analyzed at 19 microsatellite loci for species discrimination. Out of 1,423 free embryos collected over 3 years of sampling, 971 Paddlefish, 446 Shovelnose Sturgeon, and 6 Pallid Sturgeon were identified. Additionally, 249 Scaphirhynchus spp. benthic larvae were screened, but no Pallid Sturgeon were detected. These SNP markers provide an efficient method of screening acipenseriform early life stages for the presence of Pallid Sturgeon in the Missouri River basin. Detection of wild Pallid Sturgeon free embryos in the upper Missouri and Yellowstone rivers supports the hypothesis that the failure of wild Pallid Sturgeon to recruit to the juvenile life stage in the upper Missouri River basin is caused by early life stage mortality rather than by lack of successful spawning.
Wu, Feixiang; Chang, Mee-mann; Sun, Yuanlin; Xu, Guanghui
Background Equipped with an effective predatory feeding mechanism enhanced by large and sharp teeth, pointed snout and elongate body, saurichthyiform fishes are considered common fish-eaters in the early Mesozoic aquatic ecosystems. Additionally, because of the similar body plan across species, saurichthyiforms are also regarded evolutionally conservative, with few morphological and ecological changes during their long history. However, their phylogenetic affinity remains unclear as to whether they are chondrostean, neopterygian or stem-actinopteran, and likewise the intrarelationships of the group have rarely been explored. Methodology/Principal Findings Here we report a new saurichthyiform from the Middle Triassic of Guizhou, China, based on the well-preserved specimens including a 3-D braincase. The new taxon, Yelangichthys macrocephalus gen. et sp. nov., is unique among saurichthyiforms in having a peculiar neurocranium with a broad orbital tectum, paired posterior myodomes, a deep, transverse fossa in the posterodorsal part of the orbit, and a feeding mechanism structured for durophagy. Phylogenetic analysis places Yelangichthys gen. nov. at the most basal position in the Saurichthyiformes as the sister to Saurichthyidae, and a new family Yelangichthyidae is erected to include only Y. macrocephalus gen. et sp. nov. The monophyly of the Chondrostei comprising [Saurichthyiformes + Acipenseriformes] Birgeriiformes is supported, but not the monophyly of Saurichthys, the type genus of Saurichthyidae. With its outstanding osteological details, Yelangichthys gen. nov. greatly increases the neurocranial variations in saurichthyiforms, and its novel feeding structure suggests the consumption of hard-preys instead of fishes. Conclusions/Significance Our findings highlight the detailed osteology of a saurichthyiform braincase and its feeding design. We suggest that saurichthyiforms are closely allied to the Acipenseriformes. Saurichthyiforms were very diverse in the
Rastorguev, Sergey M; Nedoluzhko, Artem V; Mazur, Alexander M; Gruzdeva, Natalia M; Volkov, Alexander A; Barmintseva, Anna E; Mugue, Nikolai S; Prokhortchouk, Egor B
Abstract Legally certified sturgeon fisheries require population protection and conservation methods, including DNA tests to identify the source of valuable sturgeon roe. However, the available genetic data are insufficient to distinguish between different sturgeon populations, and are even unable to distinguish between some species. We performed high-throughput single-nucleotide polymorphism (SNP)-genotyping analysis on different populations of Russian (Acipenser gueldenstaedtii), Persian (A. persicus), and Siberian (A. baerii) sturgeon species from the Caspian Sea region (Volga and Ural Rivers), the Azov Sea, and two Siberian rivers. We found that Russian sturgeons from the Volga and Ural Rivers were essentially indistinguishable, but they differed from Russian sturgeons in the Azov Sea, and from Persian and Siberian sturgeons. We identified eight SNPs that were sufficient to distinguish these sturgeon populations with 80% confidence, and allowed the development of markers to distinguish sturgeon species. Finally, on the basis of our SNP data, we propose that the A. baerii-like mitochondrial DNA found in some Russian sturgeons from the Caspian Sea arose via an introgression event during the Pleistocene glaciation. In the present study, the high-throughput genotyping analysis of several sturgeon populations was performed. SNP markers for species identification were defined. The possible explanation of the baerii-like mitotype presence in some Russian sturgeons in the Caspian Sea was suggested. PMID:24567827
Rastorguev, Sergey M; Nedoluzhko, Artem V; Mazur, Alexander M; Gruzdeva, Natalia M; Volkov, Alexander A; Barmintseva, Anna E; Mugue, Nikolai S; Prokhortchouk, Egor B
Legally certified sturgeon fisheries require population protection and conservation methods, including DNA tests to identify the source of valuable sturgeon roe. However, the available genetic data are insufficient to distinguish between different sturgeon populations, and are even unable to distinguish between some species. We performed high-throughput single-nucleotide polymorphism (SNP)-genotyping analysis on different populations of Russian (Acipenser gueldenstaedtii), Persian (A. persicus), and Siberian (A. baerii) sturgeon species from the Caspian Sea region (Volga and Ural Rivers), the Azov Sea, and two Siberian rivers. We found that Russian sturgeons from the Volga and Ural Rivers were essentially indistinguishable, but they differed from Russian sturgeons in the Azov Sea, and from Persian and Siberian sturgeons. We identified eight SNPs that were sufficient to distinguish these sturgeon populations with 80% confidence, and allowed the development of markers to distinguish sturgeon species. Finally, on the basis of our SNP data, we propose that the A. baerii-like mitochondrial DNA found in some Russian sturgeons from the Caspian Sea arose via an introgression event during the Pleistocene glaciation. In the present study, the high-throughput genotyping analysis of several sturgeon populations was performed. SNP markers for species identification were defined. The possible explanation of the baerii-like mitotype presence in some Russian sturgeons in the Caspian Sea was suggested.
Swartz, Carol D; Donnelly, K C; Islamzadeh, Arif; Rowe, Gilbert T; Rogers, William J; Palatnikov, Grigoriy M; Mekhtiev, Arif A; Kasimov, Rafik; McDonald, Thomas J; Wickliffe, Jeffery K; Presley, Bobby J; Bickham, John W
Sediment from a wetland adjacent to an industrial wastewater treatment plant in Sumgayit contained concentrations of total PAHs, total PCBs, aldrin, biphenyl, chlordane, DDT, mercury, beta-endosulfan, heptachlor, alpha-hexacyclohexane (alpha-HCH), gamma-HCH, and several individual PAH congeners that were elevated relative to published sediment quality guidelines. Chemical analyses of tissues from European pond turtles (Emys orbicularis) had increased levels of many of the same chemicals including aldrin, chlordane, heptachlor, alpha-HCH, total PCBs, total PAHs, and mercury, compared to reference turtles. In addition, turtle tissues contained elevated levels of DDD, hexachlorobenzene (HCB), and pentachlorobenzene that were not elevated in the sediment sample. Some differences were observed in contaminant levels between European pond turtles and Caspian turtles (Mauremys caspica) taken from the ponds in Sumgayit. Salmonella/microsome mutagenicity assays on pond sediments were negative or weakly positive. Micronuclei in European pond turtles were statistically correlated with tissue levels of mercury, heptachlor, DDD, HCB, and trans-nonachlor. Microcosm experiments using Russian sturgeon (Acipenser gueldenstaedtii) showed a positive dose-response relationship between exposure to suspended contaminated pond sediment and acute toxicity. Chemical and biological assays used in this study show the industrial area of Sumgayit is heavily contaminated with a complex mixture of toxic pollutants. Exposure to contaminated sediments produced acute effects in Russian sturgeon, but genotoxic effects appear to be slight.
Kynard, B.; Suciu, R.; Horgan, M.
Upstream migrant adults of stellate sturgeon, Acipenser stellatus (10 in 1998, 43 in 1999) and Russian sturgeon, A. gueldenstaedtii (three in 1999) were captured at river km (rkm) 58-137, mostly in the spring, and tagged with acoustic tags offering a reward for return. The overharvest was revealed by tag returns (38% in 1998, 28% in 1999) and by harvest within 26 days (and before reaching spawning grounds) of the six stellate sturgeon tracked upstream. A drop-back of > 50% of the tagged sturgeon, some to the Black Sea, shows a high sensitivity to interruption of migration and capture/handling/holding. Harvesting and dropback prevented tracking of sturgeon to spawning sites. Gillnetting and tracking of stellate sturgeon showed that the autumn migration ended in early October (river temperature 16??C) and identified a likely wintering area at river km (rkm) 75-76 (St George Branch). Thus, fishery harvesting after early October captures wintering fish, not migrants. Rare shoreline cliffs in the lower river likely create the only rocky habitat for sturgeon spawning. A survey for potential spawning habitats found five sites with rocky substrate and moderate water velocity, all ???rkm 258. Drift netting caught early life-stages of 17 fish species and one sturgeon, a beluga, Huso huso, larva likely spawned at ???rkm 258. All diadromous Danube sturgeons likely spawn at ???rkm 258.
Bigarré, L; Lesne, M; Lautraite, A; Chesneau, V; Leroux, A; Jamin, M; Boitard, P M; Toffan, A; Prearo, M; Labrut, S; Daniel, P
Iridoviridae are known to cause disease in sturgeons in North America. Here, histological and molecular methods were used to screen for this family of virus in sturgeons from various European farms with low-to-high morbidity. Some histological samples revealed basophilic cells in the gill and labial epithelia, strongly suggesting the accumulation of iridovirus particles. Newly developed generic PCR tests targeting the major capsid protein (MCP) gene of sturgeon iridoviruses identified in North America, namely the white sturgeon iridovirus and the Namao virus (NV), produced positive signals in most samples from four sturgeon species: Russian (Acipenser gueldenstaedtii), Siberian (A. baerii), Adriatic (A. naccarii) and beluga (Huso huso). The sequences of the PCR products were generally highly similar one another, with nucleotide identities greater than 98%. They were also related to (74-88%), although distinct from, American sturgeon iridoviruses. These European viruses were thus considered variants of a single new virus, provisionally named Acipenser iridovirus-European (AcIV-E). Moreover, three samples infected with AcIV-E showed genetic heterogeneity, with the co-existence of two sequences differing by five nucleotides. One of our European samples carried a virus distinct from AcIV-E, but closely related to NV identified in Canada (95%). This study demonstrates the presence of two distinct sturgeon iridoviruses in Europe: a new genotype AcIV-E and an NV-related virus.
Balazik, Matthew T.; Musick, John A.
Atlantic sturgeon (Acipenser oxyrinchus oxyrinchus, Acipenseridae) populations in the United States were listed as either endangered or threatened under the Endangered Species Act in 2012. Because of the endangered/threatened status, a better understanding of Atlantic sturgeon life-history behavior and habitat use is important for effective management. It has been widely documented that Atlantic sturgeon reproduction occurs from late winter to early summer, varying clinally with latitude. However, recent data show Atlantic sturgeon also spawn later in the year. The group that spawns later in the year seems to be completely separate from the spring spawning run. Recognition of the later spawning season has drastically modified estimates of the population status of Atlantic sturgeon in Virginia. With the combination of new telemetry data and historical documentation we describe a dual spawning strategy that likely occurs in various degrees along most, if not all, of the Atlantic sturgeon's range. Using new data combined with historical sources, a new spawning strategy emerges which managers and researchers should note when determining the status of Atlantic sturgeon populations and implementing conservation measures. PMID:26020631
Chalupnicki, Marc A.; Dittman, Dawn E.
Accurate expedient species identification of deceased sturgeon (Acipenseridae) when external physical characteristic analysis is inconclusive has become a high priority due to the endangered or threatened status of sturgeon species around the world. Examination of otoliths has provided useful information to aid in population management, age and size-class analysis, understanding predator–prey interactions, and archeological research in other fish species. The relationship between otolith characteristics and sturgeon species has remained unknown. Therefore, we analyzed the shape of otoliths from the eight species of sturgeon found in North America to test the utility of otolith characteristic morphology in species identification. There were distinct differences in the size and shape of the otoliths between species of sturgeon with little shape variation among individuals of the same species. The relationship between otolith length axes was linear, and most of the variability was explained by a Log (axis + 1) transformation of the x and y axes (r2 = 0.8983) using the equation y = 0.73x + 0.0612. Images of otoliths from all eight North American species are presented to assist in the identification process.
Prokopchuk, Galina; Dzyuba, Borys; Rodina, Marek; Cosson, Jacky
Spermatozoa are stored in a quiescent state in the male reproductive tract and motility is induced in response to various environmental stimuli, such as change of osmolality (general case) and a decrease of extracellular K+ in fish from Acipenseridae family. This study was aimed to investigate the relationship between osmolality and extracellular K+ concentration in controlling sperm motility in sturgeon. Pre-incubation of sturgeon sperm for 5s in hypertonic solutions of glycerol, NaCl, or sucrose (each of 335 mOsm/kg osmolality) prepares sturgeon spermatozoa to become fully motile in presence of high concentration of K+ ions (15 mM), which has previously been demonstrated to fully repress motility. Furthermore, presence of 0.5mM KCl during the high osmolality pre-incubation exposure completely prevented subsequent spermatozoa activation in a K+-rich media. Manipulating the transport of K+ ions by the presence of K+ ionophore (valinomycin), it was concluded that once an efflux of K+ ions, the precursor of sturgeon sperm motility activation, is taking place, spermatozoa then become insensitive to a large extracellular K+ concentration.
Balazik, Matthew T; Musick, John A
Atlantic sturgeon (Acipenser oxyrinchus oxyrinchus, Acipenseridae) populations in the United States were listed as either endangered or threatened under the Endangered Species Act in 2012. Because of the endangered/threatened status, a better understanding of Atlantic sturgeon life-history behavior and habitat use is important for effective management. It has been widely documented that Atlantic sturgeon reproduction occurs from late winter to early summer, varying clinally with latitude. However, recent data show Atlantic sturgeon also spawn later in the year. The group that spawns later in the year seems to be completely separate from the spring spawning run. Recognition of the later spawning season has drastically modified estimates of the population status of Atlantic sturgeon in Virginia. With the combination of new telemetry data and historical documentation we describe a dual spawning strategy that likely occurs in various degrees along most, if not all, of the Atlantic sturgeon's range. Using new data combined with historical sources, a new spawning strategy emerges which managers and researchers should note when determining the status of Atlantic sturgeon populations and implementing conservation measures.
Koch, Jeff D.; Quist, Michael C.; Pierce, Clay L.; Hansen, Kirk A.; Steuck, Michael J.
Shovelnose sturgeon Scaphirhynchus platorynchus have become an increasingly important commercial species in the upper Mississippi River (UMR) because of the collapse of foreign sturgeon (family Acipenseridae) populations and bans on imported caviar. In response to concerns about the sustainability of the commercial shovelnose sturgeon fishery in the UMR, we undertook this study to describe the demographics of the shovelnose sturgeon population and evaluate the influence of commercial harvest on shovelnose sturgeon populations in the UMR. A total of 1,682 shovelnose sturgeon were collected from eight study pools in 2006 and 2007 (Pools 4, 7, 9, 11, 13, 14, 16, and 18). Shovelnose sturgeon from upstream pools generally had greater lengths, weights, and ages than those from downstream pools. Additionally, mortality estimates were lower in upstream pools (Pools 4, 7, 9, and 11) than in downstream pools (Pools 13, 14, 16, and 18). Linear regression suggested that the slower growth of shovelnose sturgeon is a consequence of commercial harvest in the UMR. Modeling of potential management scenarios suggested that a 685-mm minimum length limit is necessary to prevent growth and recruitment overfishing of shovelnose sturgeon in the UMR.
Flowers, H. Jared; Hightower, Joseph E.
Sturgeons (Acipenseridae) are one of the most threatened taxa worldwide, including species in North Carolina and South Carolina. Populations of Atlantic Sturgeon Acipenser oxyrinchus in the Carolinas have been significantly reduced from historical levels by a combination of intense fishing and habitat loss. There is a need for estimates of current abundance, to describe status, and for estimates of historical abundance in order to provide realistic recovery goals. In this study we used N-mixture and distance models with data acquired from side-scan sonar surveys to estimate abundance of sturgeon in six major sturgeon rivers in North Carolina and South Carolina. Estimated abundances of sturgeon greater than 1 m TL in the Carolina distinct population segment (DPS) were 2,031 using the count model and 1,912 via the distance model. The Pee Dee River had the highest overall abundance of any river at 1,944 (count model) or 1,823 (distance model). These estimates do not account for sturgeon less than 1 m TL or occurring in riverine reaches not surveyed or in marine waters. Comparing the two models, the N-mixture model produced similar estimates using less data than the distance model with only a slight reduction of estimated precision.
Chalupnicki, Marc A.; Dittman, Dawn E.
Extracting the otoliths (ear bones) from fish that have very thick skulls can be difficult and very time consuming. The common practice of making a transverse vertical incision on the top of the skull with a hand or electrical saw may damage the otolith if not performed correctly. Sturgeons (Acipenseridae) are one family in particular that have a very large and thick skull. A new laboratory method entering the brain cavity from the ventral side of the fish to expose the otoliths was easier than other otolith extraction methods found in the literature. Methods reviewed in the literature are designed for the field and are more efficient at processing large quantities of fish quickly. However, this new technique was designed to be more suited for a laboratory setting when time is not pressing and successful extraction from each specimen is critical. The success of finding and removing otoliths using this technique is very high and does not compromise the structure in any manner. This alternative technique is applicable to other similar fish species for extracting the otoliths.
Fopp-Bayat, D; Ocalewicz, K; Kucinski, M; Jankun, M; Laczynska, B
Artificial mitotic gynogenesis, a chromosome set manipulation, is applied to provide the homozygous progeny with only maternal inheritance. Here, gynogenetic development was induced in the sterlet Acipenser ruthenus L. (Acipenseridae) by activation of the eggs originating from albino females with the UV-irradiated spermatozoa from wild-coloured males, followed by the heat shock applied to suppress the first mitotic division in the haploid zygotes. All experimentally obtained gynogenetic offspring possessed recessive albino coloration. Moreover, the genetic verification, based on three microsatellite DNA markers, confirmed the only maternal inheritance in the albino progeny. Cytogenetic screening enabled identification of the aneuploids, haploids, diploids, triploids, tetraploids and mosaic individuals among the gynogenetic larvae that hatched from the eggs subjected to the heat shock. Furthermore, 40% of the larvae from the haploid variants of the research that were not exposed to the temperature shock showed the diploid chromosome number. A variation of the ploidy level observed in the gynogenetic sterlets may be the consequence of the spontaneous polyploidisation that occurred in the haploid zygotes. Moreover, observation during embryogenesis showed varied stages of eggs development and the asynchronous cell cleavages that may have resulted in the chromosomal disturbances observed in the gynogenetic sterlets here.
Schwab, Ivan R; Yuen, Carlton K; Buyukmihci, Nedim C; Blankenship, Thomas N; Fitzgerald, Paul G
PURPOSE: To review, contrast, and compare current known tapetal mechanisms and review the implications for the evolution of the tapetum. METHODS: Ocular specimens of representative fish in key piscine families, including Acipenseridae, Cyprinidae, Chacidae; the reptilian family Crocodylidae; the mammalian family Felidae; and the Lepidopteran family Sphingidae were reviewed and compared histologically. All known varieties of tapeta were examined and classified and compared to the known cladogram representing the evolution of each specific family. RESULTS: Types of tapeta include tapetum cellulosum, tapetum fibrosum, retinal tapetum, invertebrate pigmented tapetum, and invertebrate thin-film tapetum. All but the invertebrate pigmented tapetum were examined histologically. Review of the evolutionary cladogram and comparison with known tapeta suggest that the tapetum evolved in the Devonian period 345 to 395 million years ago. Tapeta developed independently in at least three separate orders in invertebrates and vertebrates, and yet all have surprisingly similar mechanisms of light reflection, including thin-film interference, diffusely reflecting tapeta, Mie scattering, Rayleigh scattering, and perhaps orthogonal retroreflection. CONCLUSION: Tapeta are found in invertebrates and vertebrates and display different physical mechanisms of reflection. Each tapetum reflects the wavelengths most relevant to the species' ecological niche. With this work, we have hypothesized that the tapetum evolved independently in both invertebrates and vertebrates as early as the Devonian period and coincided with an explosion of life forms. PMID:12545693
Smith, Moya M.; Johanson, Zerina; Butts, Thomas; Ericsson, Rolf; Modrell, Melinda; Tulenko, Frank J.; Davis, Marcus C.; Fraser, Gareth J.
Ray-finned fishes (Actinopterygii) are the dominant vertebrate group today (+30 000 species, predominantly teleosts), with great morphological diversity, including their dentitions. How dental morphological variation evolved is best addressed by considering a range of taxa across actinopterygian phylogeny; here we examine the dentition of Polyodon spathula (American paddlefish), assigned to the basal group Acipenseriformes. Although teeth are present and functional in young individuals of Polyodon, they are completely absent in adults. Our current understanding of developmental genes operating in the dentition is primarily restricted to teleosts; we show that shh and bmp4, as highly conserved epithelial and mesenchymal genes for gnathostome tooth development, are similarly expressed at Polyodon tooth loci, thus extending this conserved developmental pattern within the Actinopterygii. These genes map spatio-temporal tooth initiation in Polyodon larvae and provide new data in both oral and pharyngeal tooth sites. Variation in cellular intensity of shh maps timing of tooth morphogenesis, revealing a second odontogenic wave as alternate sites within tooth rows, a dental pattern also present in more derived actinopterygians. Developmental timing for each tooth field in Polyodon follows a gradient, from rostral to caudal and ventral to dorsal, repeated during subsequent loss of teeth. The transitory Polyodon dentition is modified by cessation of tooth addition and loss. As such, Polyodon represents a basal actinopterygian model for the evolution of developmental novelty: initial conservation, followed by tooth loss, accommodating the adult trophic modification to filter-feeding. PMID:25788604
Zhu, Lin; Yan, Zhenxin; Feng, Mengyang; Peng, Dezhi; Guo, Ying; Hu, Xiaoxiang; Ren, Liming; Sun, Yi
IgD has been found in almost all jawed vertebrates, including cartilaginous and teleost fish. However, IgD is missing in acipenseriformes, a branch that is evolutionarily positioned between elasmobranchs and teleost fish. Here, by analyzing transcriptome data, we identified a transcriptionally active IgD-encoding gene in the Siberian sturgeon (Acipenser baerii). Phylogenetic analysis indicated that it is orthologous to mammalian IgD and closely related to the IgD of other fish. The lengths of sturgeon membrane-bound IgD transcripts ranged from 1.2kb to 6.2kb, encoding 3-19 CH domains. As in teleosts, the first CH domain of the sturgeon IgD transcript is also derived from μCH1 by RNA splicing. However, the variable region of the expressed sturgeon IgD shows limited V(D)J usage. In addition to IgD, three IgM variants were also identified in this species, whereas no IgT/Z-encoding genes were observed. This study bridges the gap in Ig evolution between elasmobranchs and teleosts and provides significant insight into the early evolution of immunoglobulins.
Zelazowska, Monika; Kilarski, Wincenty
The ovary of paddlefish and sturgeons (Acipenseriformes) is composed of discrete units: the ovarian nests and ovarian follicles. The ovarian nests comprise oogonia and numerous early dictyotene oocytes surrounded by somatic prefollicular cells. Each ovarian follicle consists of a spherical oocyte and a layer of follicular cells situated on a thick basal lamina, encompassed by thecal cells. The cytoplasm of previtellogenic oocytes is differentiated into two distinct zones: the homogeneous and granular zones. The homogeneous cytoplasm is organelle-free, whereas the granular cytoplasm contains numerous organelles, including mitochondria and lipid droplets. We have analyzed the cytoplasm of early dictyotene and previtellogenic oocytes ultrastructurally and histologically. In the cytoplasm of early dictyotene oocytes, two morphologically different types of mitochondria can be distinguished: (1) with well-developed cristae and (2) with distorted and fused cristae. In previtellogenic oocytes, the mitochondria of the second type show various stages of cristae distortion; they contain and release material morphologically similar to that of lipid droplets and eventually degenerate. This process of mitochondrial transformation is accompanied by an accumulation of lipid droplets that form a single large accumulation (lipid body) located in the vicinity of the oocyte nucleus (germinal vesicle). The lipid body eventually disperses in the oocyte center. The possible participation of these mitochondria in the formation of oocyte lipid droplets is discussed.
Havelka, M; Šachlová, H; Shaliutina-Kolešová, A; Rodina, M
Species may be prevented from interspecific hybridization by a number of different reproductive barriers that operate precopulatory and postcopulatory. In situation, when natural precopulatory reproductive barriers are affected by anthropogenic factors, postcopulatory reproductive barriers may be important for maintaining gametic isolation and hence preventing interspecific hybridization. This is highly topical in sturgeon (order Acipenseriformes) which exhibits remarkable ease of interspecific hybridization. The objectives of the present study were to evaluate the fertilization success of Acipenser ruthenus and Acipenser baerii spermatozoa under the interspecific competitive conditions and assessed, whether their spermatozoa tend to differentially fertilize eggs of conspecifics. We set up several in vitro fertilization experiments: (i) pooled eggs of both species were fertilized by sperm of each species separately; (ii) eggs of each species were fertilized by pooled sperm; (iii) pooled eggs were fertilized by pooled sperm and (iv) purebred and hybrid control groups. Using parental assignment by molecular markers, we found that when these species competed in pooled sperm, 78.9% of progeny were sired by A. ruthenus and 21.1% by A. baerii, demonstrating higher fertilization success for the former, irrespective of conspecificity of fertilized eggs. When pooled eggs were inseminated by A. ruthenus or A. baerii sperm separately, progeny almost equally comprised hybrid and purebred individuals. Hence, neither A. ruthenus nor A. baerii eggs showed a tendency to biased fertilization by spermatozoa of conspecific males. These findings together show that there may not be postcopulatory mechanisms preventing hybridization between A. ruthenus and A. baerii.
Faria, M T; Carvalho, R F; Sevilhano, T C A; Oliveira, N A J; Silva, C F P; Oliveira, J E; Soares, C R J; Garcez, R; Santo, P R E; Bartolini, P
The cDNAs of the α-subunit of the pituitary gonadotrophic hormones (GTHα) of fish of the order Osteoglossiformes or the superorder Osteoglossomorpha have never been sequenced. For a better understanding the phylogenetic diversity and evolution of PGHα in fish and for future biotechnological synthesis of the gonadotrophic hormones (ag-FSH and ag-LH), of Arapaima gigas, one of the largest freshwater fishes of the world, its GTHα cDNA was synthesized by reverse transcriptase and the polymerase chain reaction starting from total pituitary RNA. The ag-GTHα-subunit was found to be encoded by 348 bp, corresponding to a protein of 115 amino acids, with a putative signal peptide of 24 amino acids and a mature peptide of 91 amino acids. Ten cysteine residues, responsible for forming 5 disulfide linkages, 2 putative N-linked glycosylation sites and 3 proline residues, were found to be conserved on the basis of the known sequences of vertebrate gonadotrophic hormones. Phylogenetic analysis, based on the amino acid sequences of 38 GTHα-subunits, revealed the highest identity of A. gigas with members of the Acipenseriformes, Anguilliformes, Siluriformes and Cypriniformes (87.1-89.5 %) and the lowest with Gadiformes and Cyprinodontiformes (55.0 %). The obtained phylogenetic tree agrees with previous analysis of teleostei, since A. gigas, of the order of Osteoglossiformes, appears as the sister group of Clupeocephala, while Elopomorpha forms the most basal group of all other teleosts.
Yom-Din, Svetlana; Hollander-Cohen, Lian; Aizen, Joseph; Boehm, Benjamin; Shpilman, Michal; Golan, Matan; Hurvitz, Avshalom; Degani, Gad; Levavi-Sivan, Berta
In the reproduction process of male and female fish, pituitary derived gonadotropins (GTHs) play a key role. To be able to specifically investigate certain functions of Luteinizing (LH) and Follicle stimulating hormone (FSH) in Russian sturgeon (Acipenser gueldenstaedtii; st), we produced recombinant variants of the hormones using the yeast Pichia pastoris as a protein production system. We accomplished to create in vitro biologically active heterodimeric glycoproteins consisting of two associated α- and β-subunits in sufficient quantities. Three dimensional modelling of both GTHs was conducted in order to study the differences between the two GTHs. Antibodies were produced against the unique β-subunit of each of the GTHs, in order to be used for immunohistochemical analysis and to develop an ELISA for blood and pituitary hormone quantification. This detection technique revealed the specific localization of the LH and FSH cells in the sturgeon pituitary and pointed out that both cell types are present in substantially higher numbers in mature males and females, compared to immature fish. With the newly attained option to prevent cross-contamination when investigating on the effects of GTH administration, we compared the steroidogeneic response (estradiol and 11-Keto testosterone (11-KT) in female and males, respectively) of recombinant stLH, stFSH, and carp pituitary extract in male and female sturgeon gonads at different developmental stages. Finally, we injected commercially available gonadotropin releasing hormones analog (GnRH) to mature females, and found a moderate effect on the development of ovarian follicles. Application of only testosterone (T) resulted in a significant increase in circulating levels of 11-KT whereas the combination of GnRH + T did not affect steroid levels at all. The response pattern for estradiol demonstrated a similar situation. FSH levels showed significant increases when GnRH + T was administered, while no changes were present in
Pujolar, José Martin; Astolfi, Laura; Boscari, Elisa; Vidotto, Michele; Barbisan, Federica; Bruson, Alice; Congiu, Leonardo
We report the discovery of a new putatively active Tc1-like transposable element (Tana1) in the genome of sturgeons, an ancient group of fish considered as living fossils. The complete sequence of Tana1 was first characterized in the 454-sequenced transcriptome of the Adriatic sturgeon (Acipenser naccarii) and then isolated from the genome of the same species and from 12 additional sturgeons including three genera of the Acipenseridae (Acipenser, Huso, Scaphirhynchus). The element has a total length of 1588bp and presents inverted repeats of 210bp, one of which partially overlapping the 3' region of the transposase gene. The spacing of the DDE motif within the catalytic domain in Tana1 is unique (DD38E) and indicates that Tana1 can be considered as the first representative of a new Tc1 subfamily. The integrity of the native form (with no premature termination codons within the transposase), the presence of all expected functional domains and its occurrence in the sturgeon transcriptome suggest a current or recent activity of Tana1. The presence of Tana1 in the genome of the 13 sturgeon species in our study points to an ancient origin of the element that existed before the split of the group 170 million years ago. The dissemination of Tana1 across sturgeon genomes could be interpreted by postulating vertical transmission from an ancestral Tana1 with a particularly slow evolutionary rate Horizontal transmission might have also played a role in the dissemination of Tana1 as evidenced by the presence of a complete copy in the genome of Atlantic salmon. Vertical and horizontal transmission are not mutually exclusive and may have concurred in shaping the evolution of Tana1.
Vicenova, Monika; Reschova, Stanislava; Pokorova, Dagmar; Hulova, Jana; Vesely, Tomas
Rapid antigen detection enzyme-linked immunosorbent assay (ELISA) testing of cell cultures with organ homogenate from fish, collected from farms with a predominance of common carp or in natural aquaculture in the Czech Republic between 1995 and 2008, identified piscine vesiculovirus in 27 of 178 samples. Using reverse transcription semi-nested PCR, targeting a 550 nucleotide region of the glycoprotein (G) gene, piscine vesiculovirus was confirmed in 23 of the 27 organ samples diagnosed by ELISA as infected. PCR products were amplified and sequenced from 18 isolates from common carp Cyprinus carpio (family Cyprinidae), 2 isolates from northern pike Esox lucius (family Esocidae), and 1 isolate each from Siberian sturgeon Acipenser baerii (family Acipenseridae), common barbel Barbus barbus (family Cyprinidae), and koi carp Cyprinus carpio koi (family Cyprinidae). The sequences (based on 401 nucleotides) clustered into 2 genogroups. The majority of isolates (n = 22), including those from sturgeon and pike, grouped with the spring viraemia of carp virus (SVCV) Genogroup I and Subgroup Id. The 22 isolates could be further subdivided into 2 groups: Id1 (n = 20) and Id2 (n = 2). A marker (a non-conservative nucleotide substitution) for the Id1 SVCV group was identified. It was specifically found in all sequences of Id1 isolates when testing SVCV originating from different countries. The remaining isolate from barbel, was classified in the pike fry-like rhabdovirus Genogroup IV. This is the first confirmation of natural SVCV infection in sturgeon and pike, and pike fry-like rhabdovirus infection in barbel. In the case of the pike fry-like rhabdovirus, this is also its first identification in the Czech Republic. According to the presence/absence of evident clinical signs of rhabdoviral disease in the 3 infected hosts, only the sturgeon seemed to be susceptible to the monitored rhabdovirus.
Dwyer, F.J.; Hardesty, D.K.; Henke, C.E.; Ingersoll, C.G.; Whites, D.W.; Augspurger, T.; Canfield, T.J.; Mount, D.R.; Mayer, F.L.
Toxicity tests using standard effluent test procedures described by the U.S. Environmental Protection Agency were conducted with Ceriodaphnia dubia, fathead minnows (Pimephales promelas), and seven threatened and endangered (listed) fish species from four families: (1) Acipenseridae: shortnose sturgeon (Acipenser brevirostrum); (2) Catostomidae; razorback sucker (Xyrauchen texanus); (3) Cyprinidae: bonytail chub (Gila elegans), Cape Fear shiner (Notropis mekistocholas) Colorado pikeminnow (Ptychocheilus lucius), and spotfin chub (Cyprinella monacha); and (4) Poecillidae: Gila topminnow (Poeciliopsis occidentalis). We conducted 7-day survival and growth studies with embryo-larval fathead minnows and analogous exposures using the listed species. Survival and reproduction were also determined with C. dubia. Tests were conducted with carbaryl, ammonia-or a simulated effluent complex mixture of carbaryl, copper, 4-nonylphenol, pentachlorophenol and permethrin at equitoxic proportions. In addition, Cape Fear shiners and spotfin chub were tested using diazinon, copper, and chlorine. Toxicity tests were also conducted with field-collected effluents from domestic or industrial facilities. Bonytail chub and razorback suckers were tested with effluents collected in Arizona whereas effluent samples collected from North Carolina were tested with Cape Fear shiner, spotfin chub, and shortnose sturgeon. The fathead minnow 7-day effluent test was often a reliable estimator of toxic effects to the listed fishes. However, in 21 % of the tests, a listed species was more sensitive than fathead minnows. More sensitive species results varied by test so that usually no species was always more or less sensitive than fathead minnows. Only the Gila topminnow was consistently less sensitive than the fathead minnow. Listed fish species were protected 96% of the time when results for both fathead minnows and C. dubia were considered, thus reinforcing the value of standard whole
Dwyer, F J; Hardesty, D K; Henke, C E; Ingersoll, C G; Whites, D W; Augspurger, T; Canfield, T J; Mount, D R; Mayer, F L
Toxicity tests using standard effluent test procedures described by the U.S. Environmental Protection Agency were conducted with Ceriodaphnia dubia, fathead minnows (Pimephales promelas), and seven threatened and endangered (listed) fish species from four families: (1) Acipenseridae: shortnose sturgeon (Acipenser brevirostrum); (2) Catostomidae; razorback sucker (Xyrauchen texanus); (3) Cyprinidae: bonytail chub (Gila elegans), Cape Fear shiner (Notropis mekistocholas) Colorado pikeminnow (Ptychocheilus lucius), and spotfin chub (Cyprinella monacha); and (4) Poecillidae: Gila topminnow (Poeciliopsis occidentalis). We conducted 7-day survival and growth studies with embryo-larval fathead minnows and analogous exposures using the listed species. Survival and reproduction were also determined with C. dubia. Tests were conducted with carbaryl, ammonia--or a simulated effluent complex mixture of carbaryl, copper, 4-nonylphenol, pentachlorophenol and permethrin at equitoxic proportions. In addition, Cape Fear shiners and spotfin chub were tested using diazinon, copper, and chlorine. Toxicity tests were also conducted with field-collected effluents from domestic or industrial facilities. Bonytail chub and razorback suckers were tested with effluents collected in Arizona whereas effluent samples collected from North Carolina were tested with Cape Fear shiner, spotfin chub, and shortnose sturgeon. The fathead minnow 7-day effluent test was often a reliable estimator of toxic effects to the listed fishes. However, in 21 % of the tests, a listed species was more sensitive than fathead minnows. More sensitive species results varied by test so that usually no species was always more or less sensitive than fathead minnows. Only the Gila topminnow was consistently less sensitive than the fathead minnow. Listed fish species were protected 96% of the time when results for both fathead minnows and C. dubia were considered, thus reinforcing the value of standard whole
Vardy, David W; Tompsett, Amber R; Sigurdson, Jacinda L; Doering, Jon A; Zhang, Xiaowei; Giesy, John P; Hecker, Markus
Populations of sturgeon (Acipenseridae) are declining in many places in the world because of several potential factors, including overharvesting, habitat alteration, and pollution. In North America, populations of the white sturgeon (Acipenser transmontanus) have been experiencing poor annual recruitment in major river systems for more than three decades. Metal pollution has been hypothesized as a potential contributing factor to the poor recruitment in some of the water bodies. In general, little is known about the toxicity of metals such as Cu, Cd, and Zn to white sturgeon and their potential influence on survival of embryos and juveniles. The present study was conducted to establish baseline toxicity data for the subchronic exposure of early life stages of white sturgeon to Cu, Cd, and Zn that can be used in metal-related risk assessments. Embryos, larvae, and fry were exposed to increasing concentrations of dissolved Cu, Cd, or Zn for 66 d using laboratory-based flow-through exposure systems. Hatching success was greater than 79% for all controls, and no significant differences were observed among treatment groups or between treatments and controls. Chronic lethal concentrations at which 20% mortality occurred (LC20s) for Cd (1.5 µg/L), Cu (5.5 µg/L), and Zn (112 µg/L) obtained for white sturgeon in the present study were comparable to those of sensitive salmonid species. Based on LC20 values for 19 or 58 d posthatch white sturgeon, the United States national ambient water quality criteria and the Canadian water quality guidelines for the protection of aquatic life that have been established for Cd, Cu, and Zn protect white sturgeon early life stages.
Crow, Karen D; Smith, Christopher D; Cheng, Jan-Fang; Wagner, Günter P; Amemiya, Chris T
Vertebrates have experienced two rounds of whole-genome duplication (WGD) in the stem lineages of deep nodes within the group and a subsequent duplication event in the stem lineage of the teleosts-a highly diverse group of ray-finned fishes. Here, we present the first full Hox gene sequences for any member of the Acipenseriformes, the American paddlefish, and confirm that an independent WGD occurred in the paddlefish lineage, approximately 42 Ma based on sequences spanning the entire HoxA cluster and eight genes on the HoxD gene cluster. These clusters comprise different HOX loci and maintain conserved synteny relative to bichir, zebrafish, stickleback, and pufferfish, as well as human, mouse, and chick. We also provide a gene genealogy for the duplicated fzd8 gene in paddlefish and present evidence for the first Hox14 gene in any ray-finned fish. Taken together, these data demonstrate that the American paddlefish has an independently duplicated genome. Substitution patterns of the "alpha" paralogs on both the HoxA and HoxD gene clusters suggest transcriptional inactivation consistent with functional diploidization. Further, there are similarities in the pattern of sequence divergence among duplicated Hox genes in paddlefish and teleost lineages, even though they occurred independently approximately 200 Myr apart. We highlight implications on comparative analyses in the study of the "fin-limb transition" as well as gene and genome duplication in bony fishes, which includes all ray-finned fishes as well as the lobe-finned fishes and tetrapod vertebrates.
Sulak, Kenneth J.; Parauka, F; Slack, W. Todd; Ruth, T; Randall, Michael; Luke, K; Mette, M. F; Price, M. E
The Gulf Sturgeon, Acipenser oxyrinchus desotoi, is an anadromous species of Acipenseridae and native to North America. It currently inhabits and spawns in the upper reaches of seven natal rivers along the northern coast of the Gulf of Mexico from the Suwannee River, Florida, to the Pearl River, Louisiana, during spring to autumn. Next to the Alligator Gar (Atractosteus spatula), the Gulf Sturgeon is currently the largest fish species occurring in U.S. Gulf Coast rivers, attaining a length of 2.35 m and weights exceeding 135 kg, but historically attained a substantially larger size. Historically, the spawning populations existed in additional rivers from which the species has been wholly or nearly extirpated, such as the Mobile and Ochlockonee rivers, and possibly the Rio Grande River. Most Gulf Sturgeon populations were decimated by unrestricted commercial fishing between 1895–1910. Subsequently most populations remained unrecovered or extirpated due to continued harvest until the 1970s–1980s, and the construction of dams blocking access to ancestral upriver spawning grounds. Late 20th Century harvest bans and net bans enacted by the several Gulf Coast states have stabilized several populations and enabled the Suwannee River population to rebound substantially and naturally. Hatchery supplementation has not been necessary in this regard to date. Sturgeon are resilient and adaptable fishes with a geological history of 150 million years. Research undertaken since the 1970s has addressed many aspects of Gulf Sturgeon life history, reproduction, migration, population biology, habitat requirements, and other aspects of species biology. However, many knowledge gaps remain, prominently including the life history of early developmental stages in the first year of life. Natural population recovery is evident for the Suwannee River population, but seems promising as well for at least four other populations. The Pascagoula and Pearl River populations face a challenging
Background Based on the observation of an increased number of paralogous genes in teleost fishes compared with other vertebrates and on the conserved synteny between duplicated copies, it has been shown that a whole genome duplication (WGD) occurred during the evolution of Actinopterygian fish. Comparative phylogenetic dating of this duplication event suggests that it occurred early on, specifically in teleosts. It has been proposed that this event might have facilitated the evolutionary radiation and the phenotypic diversification of the teleost fish, notably by allowing the sub- or neo-functionalization of many duplicated genes. Results In this paper, we studied in a wide range of Actinopterygians the duplication and fate of the androgen receptor (AR, NR3C4), a nuclear receptor known to play a key role in sex-determination in vertebrates. The pattern of AR gene duplication is consistent with an early WGD event: it has been duplicated into two genes AR-A and AR-B after the split of the Acipenseriformes from the lineage leading to teleost fish but before the divergence of Osteoglossiformes. Genomic and syntenic analyses in addition to lack of PCR amplification show that one of the duplicated copies, AR-B, was lost in several basal Clupeocephala such as Cypriniformes (including the model species zebrafish), Siluriformes, Characiformes and Salmoniformes. Interestingly, we also found that, in basal teleost fish (Osteoglossiformes and Anguilliformes), the two copies remain very similar, whereas, specifically in Percomorphs, one of the copies, AR-B, has accumulated substitutions in both the ligand binding domain (LBD) and the DNA binding domain (DBD). Conclusion The comparison of the mutations present in these divergent AR-B with those known in human to be implicated in complete, partial or mild androgen insensitivity syndrome suggests that the existence of two distinct AR duplicates may be correlated to specific functional differences that may be connected to the well