Features of inheritance of several morphological characters in the hybrids between Siberian sturgeon <Emphasis Type="Italic">Acipenser baerii</Emphasis> and beluga <Emphasis Type="Italic">A. huso</Emphasis> (Acipenseridae) and in gynogenetic individuals of Siberian sturgeon

Comparative analysis of several morphological characters is conducted in experimentally obtained hybrids between Siberian sturgeon Acipenser baerii and beluga A. huso, in parental species, and in gynogenetic progeny of Siberian sturgeon. The gynogenetic individuals are similar to Siberian sturgeon by all characters used for differentiation between Siberian sturgeon and beluga that supports gynogenetic origin of these individuals. Based on the data obtained on the hybrid specimens, the features of inheritance of the studied characters in sturgeons and their variation in postlarval ontogeny are discussed.     

Siberian sturgeon <Emphasis Type="Italic">Acipenser baerii</Emphasis> in the River Pechora

The paper reports the first reliable capture since the last 150 yr of two sturgeons in the basin of the River Pechora. Both specimens had the systematic traits of the Siberian sturgeon Acipenser baerii but differed significantly in external morphology. Data on biological traits and morphological parameters of the fish are presented. It is suggested that Pechora Basin should be included into the range of the Siberian sturgeon. Occurrences of the Siberian sturgeon in Pechora are discussed.     

Sturgeon production trials in the waste-heat effluents of a pulp and paper plant in Archangelsk, Russia

Sturgeons were cultured at the Solombalsky cellulose and paper plant (CPP) in Arkhangelsk over a 3 year period. The warm-water effluents of the biological treatment unit were utilized to rear the Siberian sturgeon (Acipenser baerii) and its hybrids with the sterlet (Acipenser ruthenus). Another culture trial included the Russian sturgeon (Acipenser gueldenstädtii) and its hybrids with the beluga (Huso huso). The most profitable culture (in terms of growth rates) was with the Siberian sturgeon and its hybrids with the sterlet. After the second year of culture, Siberian sturgeon and its hybrid averaged about 2.3 kg in wet weight while Russian sturgeons gained less (1.5 kg). One- and two-year old sturgeons grown at the Solombalsky CPP met practically all requirements needed for a successful culture.     

High‐throughput SNP‐genotyping analysis of the relationships among Ponto‐Caspian sturgeon species

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.     

Natural genetic polymorphism and phylogeography of Siberian sturgeon <Emphasis Type="Italic">Acipenser baerii</Emphasis> Brandt, 1869

Five populations of Siberian sturgeon Acipenser baerii collected throughout the species distribution range (Lake Baikal, Lena, Yenisei, Kolyma, and Irtysh rivers) were examined for genetic polymorphism using five tetraploid microsatellite loci and the mitochondrial DNA control region. It was demonstrated that Siberian sturgeon was represented by genetically well-differentiated groups that corresponded to hydrographic basins, Ob–Irtysh, Baikal–Yenisei, Lena, and Kolyma. Population assignment of the Siberian sturgeon broodstock should be considered in the restocking programs.     

Advances in the larval rearing of Siberian sturgeon

Since first large-scale attempts to culture sturgeon from the larval stage were carried out in the former U.S.S.R. at the end of the nineteenth century, rearing technology has advanced considerably during the last 20 years and noticeable improvements in incubation and larval rearing techniques have been implemented in normal hatchery procedures. Siberian sturgeon eggs are incubated in MacDonald jars at 13–14° C to prevent fungal infections. Mass hatching takes place 7 days after fertilization and hatching rate can be predicted as a function of the percentage of eggs fertilized. Survival at the end of the endogenous feeding stage is correlated with hatching rate. Egg size has no direct implications for larval growth and survival of Siberian sturgeon. Experimental studies have demonstrated that behavioural observations are useful criteria to assess the quality of larvae and to synchronize the physiological state of fish with the appropriate rearing procedures. Special attention should be given to the transition to exogenous feeding, where cannibalism, difficulties in adaptation to a new diet, overfeeding and resulting bacterial infections dramatically reduces survival to the fingerling stage. Although a commercial artificial diet specifically formulated for larvae of Siberian sturgeon and other acipenserids is still lacking, commercial non-purified rainbow trout diets and starter marine fish diets are currently used and their results are reasonably acceptable in terms of larval growth and survival. Further research must be focused on the determination of egg quality indicators in order to provide the producer with the tools to estimate the viability and performance of theprogeny.     

Effect of photoperiod on growth,physiologica and hematological indices of juvenile Siberian sturgeon <Emphasis Type="Italic">Acipenser baerii</Emphasis>

The effect of photoperiod on the growth of juvenile Siberian sturgeon Acipenser baerii has been studied in aquarium experiments. The maximum growth rate of juvenile Siberian sturgeon was observed under 12, 16, and 24 h photoperiods. This was accompanied by high respiratory rate and total food consumption and conversion. Rearing in the dark significantly decreased these indices. The hematological indices were within the normal range under optimal photoperiodic conditions. Pronounced neutrophilia and leukopenia were observed in the absence of light.     

Induction of meiotic gynogenesis in ship sturgeon Acipenser nudiventris using UV-irradiated heterologous sperm

Diploid gynogenesis was induced in ship sturgeon Acipenser nudiventris using UV-irradiated sperm from Siberian sturgeon Acipenser baerii. The optimal condition for the retention of the second polar body in ship sturgeon was determined to be 10 min after activation/fertilization in experiments. The temperature of cold shock and its duration were 2.5 °C and 30 min, respectively. A total of 30 gynogens of known parentage from experimental treatments were screened using microsatellite DNA analysis, and uniparental transmission in meiogens was confirmed. The results show that heterologous Siberian sturgeon sperm is applicable as UV-irradiated sperm for the induction of gynogenesis in ship sturgeon. This technique may recover the critically endangered sturgeon species that are becoming extinct.     

Dispermic androgenesis in sturgeons with the use of cryopreserved sperm: Production of androgenetic siberian sturgeon and androgenetic hybrids between Siberian and Russian sturgeons

Dispermic androgenesis was used to produce, for the first time, an androgenetic progeny of the Siberian sturgeon (Acipenser baerii) and the androgenetic nucleo-cytoplasmic hybrids (Siberian sturgeon, A. baerii × Russian sturgeon, A. gueldenstaedtii) using cryopreserved sperm. Microsatellite DNA analysis confirmed exclusively paternal inheritance in the androgenetic progeny of Siberian sturgeon. Heterozygotes for certain microsatellite loci were detected among the androgenetic hybrids, thereby confirming a dispermic nature of androgenesis. According to the data of comparative morphological analysis, the obtained androgenetic hybrid, by the age of 15 months old, was completely identical to the paternal species. Both a female and a male were detected in the androgenetic sturgeon progenies, which is of interest for producing bisexual progenies via androgenesis. The data of this study confirm the feasibility of dispermic androgenesis using cryopreserved sperm to preserve and recover the gene pools of endangered sturgeon species.     

Ontogenetic behavior of Siberian sturgeon, Acipenser baerii: A synthesis between laboratory tests and field data

We have reviewed field data and studies on the behavior and development of Siberian sturgeon at early-life intervals and related them to different ecologically relevant environmental factors that may play a role in the distribution, recruitment, and survival of young fish. Four behavioral phases (swimming-up, rheotactism, shoaling, and foraging) are observed from hatching to the juvenile phase. Each behavior is associated with an early-life interval and might allow fish to occupy different river habitats, directly influencing their distribution, survival, and recruitment. River current intensity, substrate typology, food resources, and predation pressure seem to be the most important factors affecting the distribution of Siberian sturgeon free embryos and larvae, while juveniles and adult fish disperse and migrate according to food abundance and reproduction. Mechanisms involved in regulating downstream migration during Siberian sturgeon early life stages are different than those observed in anadromous sturgeon species. In all large Siberian rivers, with the exception of the Lake Baikal, the Siberian sturgeon is represented by population continuums, and in many cases the foraging range also includes the spawning areas. Ontogenetic changes in Siberian sturgeon behavior could be interpreted as a species-specific mechanism to maintain the population continuums described in this species without significant mixture of local populations within the river.     

Genetic Variation of the Siberian Sturgeon (<Emphasis Type="Italic">Acipenser baerii</Emphasis> Brandt, 1869) in Aquaculture

Genetic variation of aquaculture broodstocks of the Siberian sturgeon of different origin from 13 farms across the Russian Federation was assessed at five tetraploid microsatellite loci and the mitochondrial DNA control region. At present, in aquaculture stocks of Siberian sturgeon originating from the Lena and Ob rivers, a sharp decline of haplotype diversity is observed. The most part of aquaculture individuals carry two major haplotypes characteristic of the European part of Russia (the Lena aquaculture) and two haplotypes characteristic of the western part of Siberia (the Ob aquaculture). According to the results of the microsatellite analysis, in sturgeon aquaculture stock originating from the Lena River, two genetic clusters can be distinguished. One of these clusters is represented by the stocks composed of inbred individuals and, because of this, is characterized by depleted allelic variation and the loss of rare alleles.     

三种鲟科鱼类和两种鲑科鱼类卵黄免疫球蛋白性质的比较

从施氏鲟(Acipenser schrencki)、小体鲟(Acipenser ruthenus)、西伯利亚鲟(Acipenser baeri)、哲罗鲑(Hucho taimen)和金鳟(Oncorhynchus mykiss)五种鱼类卵黄中分离、纯化Ig,并对其分子结构进行了初步研究。结果表明:五种鱼类卵中Ig的分子量分别为施氏鲟524kD、小体鲟468kD、西伯利亚鲟475kD、哲罗鲑为490kD,金鳟498kD,其Ig重链的相对分子量相同,约为97kD。轻链的相对分子量各不相同,施氏鲟为27kD,小体鲟28.5kD,西伯利亚鲟30kD,哲罗鲑28.5kD和金鳟16kD。其中西伯利亚鲟、施氏鲟和小体鲟Ig等电点约为5.85,哲罗鲑和金鳟的Ig等电点约为6.55,其蛋白质结构上具有一定的相似性,且均为糖蛋白     

Dispermic androgenesis in sturgeons with the help of cryopreserved sperm: production of androgenetic hybrids between Siberian and Russian sturgeons

Dispermic androgenesis was used to produce, for the first time, an androgenetic progeny of the Siberian sturgeon (Acipenser baerii) and the androgenetic nuclear cytoplasmic hybrids (Siberian sturgeon, A. baerii x Russian sturgeon, A. gueldenstaedtii) using cryopreserved sperm. Microsatellite DNA analysis confirmed exclusively paternal inheritance in the androgenetic progeny of Siberian sturgeon. Heterozygotes for certain microsatellite loci were detected among the androgenetic hybrids, thereby confirming a dispermic nature of androgenesis. According to the data of comparative morphological analysis, the obtained androgenetic hybrid, by the age of 15 months old, was completely identical to the paternal species. Both a female and a male were detected in the androgenetic sturgeon progenies, which is of interest for producing bisexual progenies via androgenesis. The data of this study confirm the feasibility of dispermic androgenesis using cryopreserved sperm to preserve and recover the gene pools of endangered sturgeon species.     

Comparison of the Effects of Gonadotropic Preparations of the Carp and Stellate Sturgeon Pituitaries onin vivoand in vitroOocyte Maturation in the Siberian Sturgeon Acipenser baeriBrandt

Injections of 2.5 mg/kg of stellate sturgeon (Acipenser stellatusPall.) pituitary extract and 5 mg/kg of carp (Cyprinus carpioL.) pituitary extract in Siberian sturgeon (Acipenser baeriBrandt) females did not reveal significant differences in the effects of these preparations. There were no differences in the percentage of females that responded by ovulation, duration of the period from injection to ovulation, rate of ovulation, or quality of mature eggs as estimated by the percentage of fertilization or percentage of normal embryos at the small yolk plug stage. Thus, an insufficient efficiency in the artificial reproduction of the Siberian sturgeon grown in captivity is not related to the use of the carp pituitary preparation as a stimulus. Estimation of the ratio of specific activities of the pituitary extracts and purified gonadotropins of the stellate sturgeon and carp by in vitrooocyte maturation has shown that it varies within wide limits as a function of the medium composition and physiological state of follicles. Hence, the ratio of activities of the gonadotropins of different species as determined by in vitromaturation of sturgeon oocytes may markedly differ from that upon injection of these preparations in breeders.     

First evidence of hybridization between endangered sterlets (Acipenser ruthenus) and exotic Siberian sturgeons (Acipenser baerii) in the Danube River

Most natural populations of Eurasian sturgeons have declined dramatically during recent decades, reaching historic low levels today. During the same period, sturgeon has become very popular in European aquaculture. Because many hatcheries are located near rivers, their unintentional escape is often documented, especially during floods. Until now, no cases of successful hybridization of these escaped fish with wild stocks have been reported. In this study, the genetic structure of a highly threatened population of sterlets (Acipenser ruthenus) from the Upper Danube was analysed as a requirement for their conservation. Surprisingly, we observed genotypes and morphotypes of Siberian sturgeon (Acipenser baerii), as well as hybrids between this species and native sterlets. This hybridization poses a serious threat for the survival of this isolated sterlet population in the upper part of the Danube. For the first time, natural reproduction is documented for Siberian sturgeon outside their natural range in Europe. This finding demonstrates the risk of extinction by hybridisation of endangered populations. We would like to stress that taking into consideration the risks for native sturgeon populations, farmed sturgeon should not be released into the wild, and all measures should be taken to prevent their accidental escape.     

Induced androgenesis in acipenserids may be obtained by ultraviolet radiation

The results are presented on haploid androgenesis in Siberian sturgeon and sterlet induced by UV irradiation of ovicells. During irradiation, the cells in Ringer solution were rotated around a UV lamp. The efficiency of genetic inactivation of ovicells was estimated by the following parameters: manifestation of Hertwig effect, the fraction of embryos demonstrating haploid syndrome at final developmental stages, by arrest of embryonic development in hybrids Siberian sturgeon × great sturgeon, and by absence of maternal alleles of microsatellite loci in embryos. The dose-effect curve suggests that, during UV irradiation of ovicells of Siberian sturgeon, the complete genetic inactivation is attained at exposition of 120 s, while that in sterlet is 90 or 105 s. The results show a principal possibility of inactivation of ovicells by UV irradiation and use of such cells for producing androgenetic progeny of acipenserids.     

Characterization,tissue distribution of resistin gene and the effect of fasting and refeeding on resistin mRNA expression in Siberian sturgeon (Acipenser baerii)

Resistin as an adipokine identified from rodents in 2001 is involved in many biological processes. However, little is known about this gene in fish. We cloned Siberian sturgeon (Acipenser baerii) resistin cDNA of 795 base pairs, encoding 107 amino acids, which showed 38–40% identity to human and rodents. Real-time quantitative PCR showed that the resistin gene was widely distributed in tissues of Siberian sturgeon, with the highest expression in liver. After fasting for 1, 3, 6 and 10 days, the expression of the resistin gene in the liver of Siberian sturgeon decreased significantly, and after refeeding on the 10 days of fasting the resistin mRNA expression increased rapidly, suggesting that resistin may play an important role in liver in response to starvation. Taken together, these results suggest that resistin may be involved in the regulation of energy homeostasis in liver.     

西伯利亚鲟AdipoR克隆、组织分布及其对禁食的响应

为了探究西伯利亚鲟脂联素受体的表达特征及其对能量状态变化的响应,研究采用RACE方法克隆获得AdipoR1和AdipoR2的cDNA全长。西伯利亚鲟AdipoR1 cDNA全长为2013 bp,开放阅读框为1146 bp;AdipoR2 cDNA全长为1590 bp,开放阅读框为1086 bp。多重序列比对结果显示,西伯利亚鲟AdipoR1与哺乳类、鸟类、两栖类和鱼类的氨基酸一致性较高, AdipoR2与鱼类氨基酸一致性更高。系统进化树分析显示,西伯利亚鲟AdipoR1与其他硬骨鱼类聚为一支, AdipoR2与斑点雀鳝聚为一支。实时荧光定量结果显示,AdipoR1和AdipoR2 mRNA在西伯利亚鲟组织中均有表达, AdipoR1在中脑、延脑、前脑、小脑和下丘脑中的表达高于外周组织, AdipoR2在中脑、鳃、瓣肠、性腺和延脑的表达相对较高。此外,与其他硬骨鱼类似,西伯利亚鲟AdipoR1和AdipoR2在肌肉中表达较低。当禁食10d时,西伯利亚鲟幼鱼肌肉中AdipoR1和AdipoR2mRNA表达量均显著上调,复投喂后AdipoR1表达显著降低,而AdipoR2表达无显著变化。由上...     

Comparison of the effects of gonadotropic preparations of the carp and stellate sturgeon pituitaries on in vivo and in vitro oocyte maturation in the Siberian sturgeon Acipenser baeri brandt

Injections of 2.5 mg/kg of stellate sturgeon (Acipenser stellatus Pall.) pituitary extract and 5 mg/kg of carp (Cyprinus carpio L.) pituitary extract in Siberian sturgeon (Acipenser baeri Brandt) females did not reveal significant differences in the effects of these preparations. There were no differences in the percentage of females that responded by ovulation, duration of the period from injection to ovulation, rate of ovulation, or quality of mature eggs as estimated by the percentage of fertilization or percentage of normal embryos at the small yolk plug stage. Thus, an insufficient efficiency in the artificial reproduction of the Siberian sturgeon grown in captivity is not related to the use of the carp pituitary preparation as a stimulus. Estimation of the ratio of specific activities of the pituitary extracts and purified gonadotropins of the stellate sturgeon and carp by in vitro oocyte maturation has shown that it varies within wide limits as a function of the medium composition and physiological state of follicles. Hence, the ratio of activities of the gonadotropins of different species as determined by in vitro maturation of sturgeon oocytes may markedly differ from that upon injection of these preparations in breeders.     

Features of gustatory system morphology in early juveniles of Siberian sturgeon <Emphasis Type="Italic">Acipenser baerii</Emphasis> (Acipenseridae,Acipenseriformes)

Investigation of the structure of the gustatory apparatus and morphometric features of the brain in two age groups (1.5 and 6 months) of Siberian sturgeon Acipenser baerii shows a well-developed gustatory system in all studied exemplars. In the oral cavity of the sturgeon, 14 sensory zones are separated, and eight zones are supplied by gustatory receptors. During the growth of the juveniles, morphometric parameters of the zones can change. The zones of the dorsal and ventral linings of the oral cavity are similar by morphology and size, and they are complementary. The largest zone of the oral cavity of the sturgeon with a complex structure is the palate organ. The taste buds of the sturgeon are characterized by a large variation in shapes of apical protrusions of receptor cells. Weight indices of the brain parts and estimated sensory coefficients show an increasing degree of development of the gustatory and olfactory systems during growth of the juveniles. Two age groups of the juveniles are characterized by similar morphometric parameters of the gustatory receptor apparatus with external localization, but the morphology of the gustatory apparatus of the oral cavity is different. The features of the gustatory system morphology are discussed in connection with biology of the species.