Generative and somatic production of female sturgeon at a research farm in Primorsky Krai as a basis for manufacturing gastronomic caviar

The generative and somatic characteristics of female sturgeon of five species and three hybrid forms, which were reared at the TINRO Center’s warm-water cage farm at the north of Primorsky Krai and used in caviar production, are considered. Data on the somatic growth, roe output, functional fecundity, mean egg weight, and gonadosomatic index of the female Amur Sturgeon, Kaluga, Siberian Sturgeon of the Lena and the Baikal populations, Sterlet of the Volga population, hybrids of Russian Sturgeon and Siberian Sturgeon, hybrids of Siberian Sturgeon and Amur Sturgeon, and hybrids of Kaluga and Amur Sturgeon are analyzed. The sexual maturity age and interspawning intervals are defined in the studied females. Domesticated females of all the species are shown to mature a few years earlier than those in natural conditions and to have a greater body weight. The interspawning intervals shorten by a few years in domesticated females. Most female Sterlet and some females from both populations of Siberian Sturgeon spawn annually, while the remainder spawn once in 2 years. The interspawning intervals in two species of sturgeon that inhabit the Amur River and in hybrid forms usually last for 2 years. With age, values of characteristics such as roe amount, fecundity, mean egg weight, and roe output relative to body weight grow in females spawning for the second time in the warm-water farm. The maximum roe output is found in female Kalugas at the second spawning. Then the species follow in the order of decreasing of roe output: Amur Sturgeon, hybrids of Amur Sturgeon with Kaluga, hybrids of Siberian Sturgeon with Amur Sturgeon, hybrids of Russian Sturgeon with Siberian Sturgeon, Siberian Sturgeon of the Baikal population, Siberian Sturgeon of the Lena population, and Sterlet. The hybrid between the Russian Sturgeon and Siberian Sturgeon shows the best processability and survivability characteristics; the Amur Sturgeon and Sterlet follow.     

Unidirectional hybridization of kaluga <Emphasis Type="Italic">Acipenser dauricus</Emphasis> Georgi, 1775 and Amur sturgeon <Emphasis Type="Italic">Acipenser schrenckii</Emphasis> Brandt, 1869, inferred from the mitochondrial DNA genotyping of their natural hybrids

In 2009 through 2011, among 730 individuals of kaluga and Amur sturgeon collected in the lower reaches of the Amur River and the Amursky Liman, 17 morphologically intermediate individuals (hybrids) with the body length of 56 to 202 cm (median, 81 cm) were identified, including 11 individuals (4.6%) found in 2009, three individuals (1.6%) found in 2010, and three individuals (1.1%), in 2011. In 16 hybrids, 819 bp of the mtDNA control regions were sequences and 11 haplotypes were identified. Since all these haplotypes were from the mtDNA lineages of kaluga, it was concluded that hybridization occurred in one direction, kaluga (♀) × Amur sturgeon (♂). This asymmetry could be caused by the large size differences between these species. Since the earlier examined morphologically typical Amur sturgeons showed the absence of alien haplotypes (Shedko et al., 2015), the absence of the mtDNA introgression is claimed. This can be caused by low viability or sterility of the backcross females (kaluga (♀) × Amur sturgeon (♂)) × Amur sturgeon (♂). The samples of hybrids and typical kaluga individuals demonstrated no differences in the frequency spectra of the mtDNA haplotypes. However, haplotype and nucleotide diversity in the first sample was somewhat higher than in the second one (0.950 versus 0.927 and 0.0054 versus 0.0044, respectively). The data obtained will be useful for population monitoring of kaluga and Amur sturgeon, Amur River endemics, which are classified as critically endangered by the IUCN Red List of Threatened Species.     

A new strain group of common carp: The genetic differences and admixture events between Cyprinus carpio breeds

Common carp (Cyprinus carpio) has an outstanding economic importance in freshwater aquaculture due to its high adaptive capacity to both food and environment. In fact, it is the third most farmed fish species worldwide according to the Food and Agriculture Organization. More than four million tons of common carp are produced annually in aquaculture, and more than a hundred thousand tons are caught from the wild. Historically, the common carp was also the first fish species to be domesticated in ancient China, and now, there is a huge variety of domestic carp strains worldwide. In the present study, we used double digestion restriction site‐associated DNA sequencing to genotype several European common carp strains and showed that they are divided into two distinct groups. One of them includes central European common carp strains as well as Ponto–Caspian wild common carp populations, whereas the other group contains several common carp strains that originated in the Soviet Union, mostly as cold‐resistant strains. We believe that breeding with wild Amur carp and subsequent selection of the hybrids for resistance to adverse environmental conditions was the attribute of the second group. We assessed the contribution of wild Amur carp inheritance to the common carp strains and discovered discriminating genes, which differed in allele frequencies between groups. Taken together, our results improve our current understanding of the genetic variability of common carp, namely the structure of natural and artificial carp populations, and the contribution of wild carp traits to domestic strains.     

Fertility of females of sturgeon hybrids obtained from species with different levels of ploidy (Acipenser ruthenus and A. dauricus) and their cloning

Main purpose of this work is the identification of females of artificial sturgeon hybrids capable to produce unreduced oocytes. The importance of this task is due to the ability to receive clonal all-female lines. Experiments were performed on the previously obtained reciprocal hybrids of sterlet, Acipenser ruthenus (S) with ~120 chromosomes and kaluga, Acipenser dauricus (K) with ~260 chromosomes. Karyotypes of backcross hybrids of (S × K) female (obtained by crossing sterlet female with kaluga male) and sterlet male included 180 – 190 chromosomes. This means that (S × K) female produced eggs with ~125 chromosomes and its karyotype consisted of ~250 chromosomes. This number was confirmed by a comparative analysis of erythrocyte size in this female and species with different ploidy. Karyotype with ~250 chromosomes can occur in (S x K) female only as a result of fertilization of a diploid sterlet egg (120 chromosomes) with kaluga haploid sperm (~130 chromosomes). Eggs of hybrid fertile (S × K) female, inseminated with inactivated sperm of Amur sturgeon and sterlet, developed into viable gynogenetic offspring, confirmed by the analysis of five microsatellite loci in this progeny, (S x K) female, and males used for UV-inactivated sperm. These data allow us to propose a method for obtaining fertile females of sturgeon hybrids from species with different ploidy. For this, experimentally obtained diploidized eggs from diploid 120-chromosome species must be fertilized by 250–270-chromosome male. Karyotypes of backcross hybrids of (K × S) female (obtained by crossing kaluga female with sterlet male) and sterlet male included ~250 chromosomes and hybrids of this female with kaluga male had ~320 chromosomes. These results proved an ability of hybrid (K × S) female to produce unreduced eggs, resulting in triploid backcrosses. The absence of reduction during egg development is well known in clonal forms (species) of vertebrates, which are of hybrid origin, and in artificially created fish hybrids. However, this has not been reported previously for sturgeons. Insemination of eggs of (K × S) female with UV-inactivated sperm of sterlet and Amur sturgeon led to offspring generation for which the genetic identity to their mother was proved using microsatellite analysis. That is, clonal inheritance was observed. These results suggest the possibility of developing a technology to produce all-female offspring. Artificial production of clonal lines in hybrid vertebrates can be also considered as experimental reproduction of the first stages of reticular speciation in nature.     

Age structure of juvenile Amur sturgeon Acipenser schrenckii and kaluga Huso dauricus in the Fuyuan reach of the Amur River,Northeast China

Amur sturgeon Acipenser schrenckiii Brandt 1869 and kaluga Huso dauricus (Georgi 1775) are critically endangered species with populations showing significant decline from historical levels due to overexploitation, yet little is known about their population structure. Adults are not often captured in the Fuyuan reach of the Amur River, Heilongjiang Province, Northeast China, and the government prioritizes juvenile sturgeon management. This study was conducted to determine the age and length/weight relationships of juvenile Amur sturgeon and kaluga in the Fuyuan reach of the Amur River. We estimated age using pectoral fin spine sections obtained from 65 juvenile Amur sturgeon and 50 juvenile kaluga. We compared the age estimates from two readers, and found 100% between‐reader agreement in 67.7% of the Amur sturgeon and 64.0% of the kaluga. The majority of differences in estimated age were within 1 year. Length/weight relationships (LWR) were calculated, and the LWR of the Amur sturgeon and kaluga were W = 0.0025L3.106 (r² = 0.966）and W = 0.0022L3.175 (r² = 0.989), respectively. Our study provides the age structure and LWR in juveniles of two sturgeon species.     

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     

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

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

Endemic sturgeons of the Amur River: kaluga, Huso dauricus, and Amur sturgeon, Acipenser schrenckii

General biological characteristics and the contemporary status of the kaluga, Huso dauricus, and Amur sturgeon, Acipenser schrenckii, are described. Both inhabit the Amur River basin. Kaluga is the largest freshwater fish in this river system reaching more than 5.6 m in length and more than 1000 kg in weight. We recognize four populations of kaluga: the first is from the estuary of the Amur River and coastal brackish waters of the Sea of Okhotsk and Sea of Japan, the second is from the lower Amur River, the third is from the middle-Amur, and the fourth occurs in lower reaches of the Zeya and Bureya rivers. Freshwater and brackish water morphs exist in the estuary population, with the freshwater morph predominating in number. The number of individuals in the lower Amur River population at age 2 or greater was recently estimated to be 40 000, and in the middle Amur, 30 000. The population will continue to decline because of rampant overfishing. The Amur sturgeon is represented in the Amur River basin by two morphs: brown and gray. Brown morphs occur in the middle and lower parts of the Amur River; they grow more slowly than the gray ones. Today, the lower Amur River population of Amur sturgeon is made up of 95 000 fish at age 2 or greater and is approximately half as large as the population in the middle Amur River. Populations of kaluga and Amur sturgeon in the Zeya and Bureya rivers are extremely small and on the verge of extinction.     

Genetic characterization of Amur sturgeon <Emphasis Type="Italic">Acipenser schrenckii</Emphasis> and its hybrid caught around Hokkaido

Genetic characterization was performed in five individuals of wild Amur sturgeon Acipenser schrenckii, and/or its presumed hybrid caught around Hokkaido, using a mitochondrial DNA (mtDNA) marker and two markers of nuclear DNA (nDNA). Genetic analyses indicated that two of the five fish had the mtDNA haplotype of Kaluga, Huso dauricus, whereas the nDNA markers indicated signs for both A. schrenckii and H. dauricus genotypes, referring to a hybrid origin. The other three fish were plausibly pure A. schrenckii. The results indicated the importance of combined usage of mtDNA and nDNA markers for correct species identification in sturgeon.     

Genetic diversity and differentiation of Russian common carp (Cyprinus carpio L.) breeds inferred from RAPD markers

Polymorphic components of the common carp Cyprinus carpio L. genome were examined by means of polymerase chain reaction with random primers (RAPD-PCR). Using four primers, genetic diversity estimates were obtained for 12 populations and seven strains of Russian common carp breeds, as well as for European Hungarian common carp and Amur wild common carp (N = 87). The highest number of polymorphic loci was revealed in Angelinskii common carp, as well as in the samples of Altai common carp and Amur wild common carp (P = 23.8?18.7%), while the lowest number (12.8%) of polymorphic loci was in the BB strain of Ropsha common carp. The index of genetic diversity, H, was high (11%) in Amur wild common carp, as well as in Altai and Angelinskii common carps. In the remaining breeds, the value of this index varied from 4 to 8%. Based on summarized RAPD profile (132 bands), a dendrogram of genetic differences was constructed. In this dendrogram, all breeds examined grouped into two clusters. One of the clusters was formed by Hungarian and Angelinskii common carps, and the three samples of Altai common carp. The second cluster was formed by the group consisting of the representatives of Cherepetskskii, Stavropol, and Ropsha common carps, along with the differing from them Amur wild common carp. The observed differentiation was confirmed by the analysis of the polymorphic markers variance by the method of principle components. Evolutionary history and the reasons for genetic differentiation of Russian common carp breeds are discussed.     

Genetic diversity of the striped field mouse (Apodemus agrarius Pallas, 1771) in the Russian Far East as assessed by RAPD-PCR

Random amplified polymorphic DNA (RAPD) analysis based on polymerase chain reaction (PCR) with ten-nucleotide primers of arbitrary sequences (RAPD-PCR) was used to study the genetic characteristics of five samples of the striped field mouse (Apodemus agrarius Pallas, 1771) from the Russian Far East (Primorye, Khabarovsk krai, and Magadan oblast). Highly significant differentiation of the samples was demonstrated, the genetic diversity of each sample was estimated, and non-neutral loci were found. The genetic diversity was the highest in a population from the outskirts of Magadan and the lowest in populations from an island on the Amur River near Khabarovsk and from the village of Talon (Magadan oblast). These two last populations were found to be genetically close to each other. These results indicate that striped field mice have been repeatedly introduced to Magadan oblast. The Talon population is likely to have originated from the left bank of the Amur; the outskirts of Magadan are inhabited with a mixed population formed by mice from Primorye and other regions.     

The low level of differences between mitogenomes of the Sakhalin sturgeon <Emphasis Type="Italic">Acipenser mikadoi</Emphasis> Hilgendorf, 1892 and the green sturgeon <Emphasis Type="Italic">A. medirostris</Emphasis> Ayeres, 1854 (Acipenseridae) indicates their recent divergence

The complete mitochondrial genome of the Sakhalin sturgeon Acipenser mikadoi and two mitogenomes of the Amur sturgeon A. schrenckii were sequenced using Roche 454 technology. The mitogenomes of the green sturgeon A. medirostris (obtained from GenBank) and the Sakhalin sturgeon differ as much as the mitogenomes of two mtDNA haplogroups (SM and BG) found in the same population of the Amur sturgeon: 0.0042 ± 0.0006 and 0.0036 ± 0.0005 substitutions per site (Tamura–Nei distance, TrN), respectively. The differences of these mitogenome pairs from mitogenomes of sister species (kaluga A. dauricus and white sturgeon A. transmontanus) are 3–6 times larger: 0.0260 ± 0.0015 and 0.0102 ± 0.0008, respectively. Thus, the differences between the mitogenomes of the Sakhalin and green sturgeons can be attributed to the variability at the intraspecific level. The time that has passed since the divergence of the Sakhalin and green sturgeons is considered to be much shorter than was previously believed: approximately 0.16 rather than 9.60 million years.     

Stock structure of pallid sturgeon analyzed with microsatellite loci

Recovery efforts for the endangered pallid sturgeon (Scaphirhynchus albus) include supplementation of wild stocks with hatchery reared progeny. Identifying the extent of genetic stock structure, which has previously been detected in samples from the range extremes, will help to determine whether stock transfers might be harmful. DNA microsatellite genotypes were screened in pallid sturgeon from the upper Missouri River, lower Missouri River, middle Mississippi River and Atchafalaya River and analyzed using a combination of Bayesian model‐based and more traditional F‐statistic based methods to characterize genetic differentiation. Scaphirhynchus specimens were collected by researchers active in the recovery effort and genotypes were screened at 16 microsatellite loci. Because there is considerable genetic and morphological overlap between pallid sturgeon, shovelnose sturgeon, and their hybrids, a combination of morphological and genetic techniques were used to eliminate shovelnose and possible hybrids from the sample. Genetic differentiation was detected among samples (overall θ = 0.050, P = 0.001). Pairwise θ, genetic distances, and Bayesian assignment testing reveal that pallid sturgeon from the upper Missouri River are the most distinct group with pairwise comparisons of pallid sturgeon among all the remaining samples exhibiting lower θ values, higher genetic distances, and self assignment scores. Our results indicate that using local broodstock, when available, should be used for pallid sturgeon propagation. If local broodstock are not available, geographically proximate individuals would limit genetic differences between native and stocked individuals.     

Comparative Ontogenetic Behavior and Migration of Kaluga, Huso Dauricus, and Amur Sturgeon, Acipenser Schrenckii, from the Amur River

We conducted laboratory experiments with kaluga, Huso dauricus, and Amur sturgeon, Acipenser schrenckii, to develop a conceptual model of early behavior. We daily observed embryos (first life phase after hatching) and larvae (period initiating exogenous feeding) to day-30 (late larvae) for preference of bright habitat and cover, swimming distance above the bottom, up- and downstream movement, and diel activity. Day-0 embryos of both species strongly preferred bright, open habitat and initiated a strong, downstream migration that lasted 4 days (3 day peak) for kaluga and 3 days (2 day peak) for Amur sturgeon. Kaluga migrants swam far above the bottom (150cm) on only 1 day and moved day and night; Amur sturgeon migrants swam far above the bottom (median 130cm) during 3 days and were more nocturnal than kaluga. Post-migrant embryos of both species moved day and night, but Amur sturgeon used dark, cover habitat and swam closer to the bottom than kaluga. The larva period of both species began on day 7 (cumulative temperature degree-days, 192.0 for kaluga and 171.5 for Amur sturgeon). Larvae of both species preferred open habitat. Kaluga larvae strongly preferred bright habitat, initially swam far above the bottom (median 50–105cm), and migrated downstream at night during days 10–16 (7-day migration). Amur sturgeon larvae strongly avoided illumination, had a mixed response to white substrate, swam 20–30cm above the bottom during most days, and during days 12–34 (most of the larva period) moved downstream mostly at night (23-day migration). The embryo–larva migration style of the two species likely shows convergence of non-related species for a common style in response to environmental selection in the Amur River. The embryo–larva migration style of Amur sturgeon is unique among Acipenser yet studied.     

鲟分枝杆菌病及其病原研究

20092010年间,我国人工养殖的中华鲟（Acipenser sinensis）、史氏鲟（Acipenser schrencki）和杂交鲟（hybrid sturgeon:A. baeri-A. gueldenstaedtii）暴发了细菌性疾病。患病鲟通过组织切片观察,病原菌的分离、鉴定以及组织样品中病原菌的检测,结果显示从19条患病鲟中分离到49株分枝杆菌。病原菌经过多个保守基因的测序分析和部分生理生化特征的鉴定,共发现有7种分枝杆菌,分别为龟分枝杆菌（Mycobacterium chelonae）、海分枝杆菌（Mycobacterium marinum）、戈登氏分枝杆菌（Mycobacterium gordonae）、偶发分枝杆菌（Mycobacterium fortuitum）、苏尔加分枝杆菌（Mycobacterium szulgai）、猪分枝杆菌 （Mycobacterium porcinum）和Mycobacterium arpuense。在诊断过程中发现两种或三种分枝杆菌同时存在于同一样品中,分子生物学的诊断结果表明分枝杆菌复合感染十分常见,而海分枝杆菌是分枝杆菌复合感染中最为常见的分枝杆菌。分离的病原菌对斑马鱼的攻毒试验结果表明在以上7种分枝杆菌中海分枝杆菌的毒力最强。以上结果表明海分枝杆菌是鲟分枝杆菌病的主要致病菌,分枝杆菌复合感染是鲟分枝杆菌病的主要感染形式。研究中史氏鲟和中华鲟的分枝杆菌病,以及在病鱼体内分离的猪分枝杆菌和M. arupense在国内外均尚未见报道。       

RAPD variation within and among species of Melittobia westwood (Hymenoptera: Eulophidae)

The genus Melittobia Westwood comprises several species of microparasitoids and only two of them are know to occur in Brazil up to now: M. australica Girault and M. hawaiiensis Perkins. Nevertheless, the differentiation between these two species using traditional taxonomy is very difficult. In the present study, we used random amplified polymorphic DNA chain reaction (RAPD-PCR) to test for its ability to discriminate between these two species and to examine the genetic variation among the studied populations of M. australica. Most of the generated fragments were species-specific, occurring in all individuals of one species and absent in the individuals of the other species demonstrating the appropriateness of such technique to distinguish between both of the Melittobia species occurring in Brazil. RAPD-PCR also demonstrated low variability among different populations of M. australica, which may be due to a founder effect and/or high dispersion capacity of these populations. Genetic distances within (D = 1.19-3.54%) and among populations (D = 1.93-5.28%) presented very low values, reflecting the reduced genetic variation that exists among populations of M. australica.     

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.     

Molecular identification and the features of genetic diversity in interspecific hybrids of Amur sturgeon ( Acipenser schrenckii × A. baerii, A. baerii × A. schrenckii, A. schrenckii × A. ruthenus , and A. ruthenus × A. schrenckii ) based on variability of multilocus RAPD markers

The method of polymerase chain reaction with random primers (RAPD PCR) was used to identify the progeny of the crosses between three sturgeon species, Amur sturgeon (Acipenser schrenckii Brandt, 1869), Siberian sturgeon (A. baerii Brandt, 1869), and sterlet (A. ruthenus Linnaeus, 1758). Using ten primers, genetic variation in 70 yearlings, produced in seven individual crosses: Acipenser schrenckii × A. schrenckii, A. baerii × A. baerii, A. ruthenus × A. ruthenus, A. schrenckii × A. baerii, A. baerii × A. schrenckii, A. schrenckii × A. ruthenus, and A. ruthenus × A. schrenckii was described and evaluated. It was demonstrated that the samples composed of hybrids from individual crosses were more variable than the samples of parental species. On the other hand, pooled samples of hybrids from two cross directions were genetically less variable than the pooled samples of their parents. The three main features of the hybrid RAPD profiles identified included: (1) preservation of marker DNA fragments of both parents in one genome; (2) presence of specific DNA fragments, absent from both parents; and (3) dependence of the frequency of some DNA fragments from the cross direction. Multidimensional scaling clearly distinguishes in the space of three coordinates the individuals of original species and the hybrid progeny with differentiation in the groups of direct and backcross hybrids. Analysis of relationships (UPGMA and NJ) pointed to substantial differentiation between the species, as well as between the species and hybrid progeny. Close genetic relationships between direct and backcross hybrids were demonstrated. Multilocus RAPD markers in association with statistical methods are considered to be the useful tool for discrimination of interspecific hybrids of sturgeon. Possible reasons for the differences in the hybrid RAPD profiles are discussed. Original Russian Text ? K.V. Rozhkovan, G.N. Chelomina, E.I. Rachek, 2008, published in Genetika, 2008, Vol. 44, No. 11, pp. 1453–1460.     

几种鲟鱼基因组大小、倍体的特性及鲟形目细胞进化的探讨

采用Ｆｅｕｌｇｅｎ－显微分光光度计方法,以鸡红细胞为标准ＤＮＡ（３．２２ｐｇ／２Ｃ）测定了长江白鲟、达氏鲟、中华鲟、史氏鲟和北美匙吻鲟的体细胞基因组大小（ＤＮＡ含量）。结果表明,上述五种鲟鱼ＤＮＡ含量分别为４．１１、８．２６、９．０７、６．０７和３．９６ｐｇ。长江白鲟和北美匙吻鲟均属于四倍体鱼类,分布在长江水系的中华鲟和达氏鲟两种鲟属鱼类为八倍体类型。史氏鲟初步判断为八倍体,据分析可能存在四倍体的     

Species and hybrid identification of sturgeon caviar: a new molecular approach to detect illegal trade

Overexploitation of wild populations due to the high economic value of caviar has driven sturgeons to near extinction. The high prices commanded by caviar on world markets have made it a magnet for illegal and fraudulent caviar trade, often involving low‐value farmed caviar being sold as top‐quality caviar. We present a new molecular approach for the identification of pure sturgeon species and hybrids that are among the most commercialized species in Europe and North America. Our test is based on the discovery of species‐specific single nucleotide polymorphisms (SNPs) in the ribosomal protein S7, supplemented with the Vimentin gene and the mitochondrial D‐loop. Test validations performed in 702 specimens of target and nontarget sturgeon species demonstrated a 100% identification success for Acipenser naccarii, A. fulvescens, A. stellatus, A. sinensis and A. transmontanus. In addition to species identification, our approach allows the identification of Bester and AL hybrids, two of the most economically important hybrids in the world, with 80% and 100% success, respectively. Moreover, the approach has the potential to identify many other existing sturgeon hybrids. The development of a standardized sturgeon identification tool will directly benefit trade law enforcement, providing the tools to monitor and regulate the legal trade of caviar and protect sturgeon stocks from illicit producers and traders, hence contributing to safeguarding this group of heavily threatened species.