4种鲟鱼养殖亲鱼群体遗传多样性分析

近年鲟鱼人工繁殖技术促进了鲟鱼养殖业的发展,但在选育初期未对后备亲鱼进行遗传背景分析,为了抑制种质资源退化和防止近交衰退,繁育场需要对现有后备亲鱼进行遗传背景分析.本文利用线粒体控制区(D-loop)部分序列对4种养殖鲟鱼后备亲鱼群体(共120个样本)的遗传多样性进行了分析.研究发现不同种鲟鱼D-loop部分序列长度不...     

Identification of microsatellite loci in lake sturgeon,Acipenser fulvescens,and their variability in green sturgeon,A. medirostris

From (CATC)_n, (GATA)_n, (AAAC)_n, and (CA)_n–enriched libraries for the lake sturgeon Acipenser fulvescens, 254 primer pairs were developed. These primer pairs resulted in the identification of 128 microsatellite loci in either A. fulvescens or A. medirostris. Polymorphic loci were identified in both sturgeon species for 48 of the primer pairs and 14 of the primer pairs amplified polymorphic loci only in A. medirostris. Most of the identified loci appear to be tetrasomic (79.1% in A. fulvescens and 64.5% in A. medirostris). These results offer estimates of the degree of diploidization in each of these species.     

4龄中华鲟垂体的EST分析

表达序列标签 (Expressed sequence tag, EST) 是鉴定基因表达规律和发现新基因的一种有效的分子生物学手段。为了能在中华鲟(Acipenser sinensis Gray) 中发现与生长和生殖内分泌调控相关的基因,我们构建了中华鲟垂体的SMART cDNA质粒文库。垂体是调节生长和生殖内分泌的重要器官。在本研究中,通过测序筛选得到了944个EST克隆,将所得EST 与 GenBank 数据库中的序列进行比对, 结果表明,802 (84.96%) 个克隆可以找到同源序列,共代表461个基因, 其中含132个已知功能基因;而 142 (15.04%) 个克隆不能找到同源序列。研究发现,在所有基因中,阿黑皮素原基因 (Proopiomelanocortin, POMC) 是出现次数最高的基因,占总EST数的10.17%, 显示出其在垂体中的重要地位。我们还发现了7个未知功能的基因并重点研究了其在心脏、肝脏、脾脏、肾脏、肌肉、精巢、卵巢和垂体等组织中的表达特异性。结果发现,4个基因：EG009334、EG009337、EG009338 和 EG009340为垂体特异性表达或垂体和卵巢特异性表达。对这些基因进一步的功能研究将有利于我们更好地了解中华鲟生长和生殖内分泌调控的分子机制。     

Evaluation of a remnant lake sturgeon population’s utility as a source for reintroductions in the Ohio River system

The selection of an appropriate source population may be crucial to the long-term success of reintroduction programs. Appropriate source populations often are those that originate from the same genetic lineage as native populations. However, source populations also should exhibit high levels of genetic diversity to maximize their capacity to adapt to variable environmental conditions. Finally, it is preferable if source populations are genetically representative of historical lineages with little or no contamination from non-native or domesticated stocks. Here, we use nuclear (microsatellite) and cytoplasmic (mitochondrial control region) markers to assess the genetic suitability of a potential source population inhabiting the White River in Indiana: the last extant lake sturgeon population in the Ohio River drainage. The White River population exhibited slightly lower levels of genetic diversity than other lake sturgeon populations. However, the population’s two private microsatellite alleles and three private haplotypes suggest a unique evolutionary trajectory. Population assignment tests revealed only two putative migrants in the White River, indicating the population has almost completely maintained its genetic integrity. Additionally, pairwise F _ST estimates indicated significant levels of genetic divergence between the White River and seven additional lake sturgeon populations, suggesting its genetic distinctiveness. These data indicate that the White River population may be the most suitable source population for future lake sturgeon reintroductions throughout the Ohio River drainage. Furthermore, the White River population appears to be a reservoir of unique genetic information and reintroduction may be a necessary strategy to ensure the persistence of this important genetic lineage.     

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.     

Nonconcordant evolutionary history of maternal and paternal lineages in Adriatic sturgeon

Although analyses of intraspecific variability are an important prerequisite for species identification assays, only a few studies have focused on population genetics and historical biogeography of sturgeon species. Here we present the first study on genetic variability of the last remaining Adriatic sturgeon, Acipenser naccarii, derived from mitochondrial and nuclear DNA. Our mitochondrial DNA analyses arranged individuals into three distinguished mitochondrial DNA haplogroups (Po1, Po2 and Buna). Two haplogroups (Po1 and Buna) were correlated to geographical distribution, whereas the third (Po2) was not. It was, however, very closely related to one lineage of its Ponto-Caspian sister species, A. gueldenstaedtii. The distribution of nuclear markers (microsatellites and amplified fragment length polymorphism) was strongly correlated to geographical distribution. An assignment test based on nuclear data placed no specimen of A. naccarii to A. gueldenstaedtii and vice versa. Therefore, the presence of gueldenstaedtii-like haplotypes within the Po population is either the result of a postglacial introgression or an ancestral polymorphism and does not indicate a hybrid population. The most valuable tool for forensic species identification purposes is one diagnostic deletion separating all A. naccarii from A. gueldenstaedtii. As both A. naccarii populations are genetically differentiated, stocking of sturgeon from the Po River in Italy into waters of the Buna River would jeopardize the genetic differences between both populations and should thus be avoided.     

Can juvenile Baltic sturgeon (Acipenser oxyrinchus) smell the enemy?

Atlantic sturgeon (Acipenser oxyrinchus), also known as Baltic sturgeon, is considered extinct in German waters. Fish‐rearing for conservation purposes largely relies on classical hatchery technology focusing on traits like survival and growth in captivity but rarely focusing on subsequent life in the wild, lacking skills such as foraging or anti‐predation behavior. Predation is hence a major factor for mortality in newly stocked individuals. The aim of this study was to evaluate if naïve Baltic sturgeon juveniles were able to recognize a common predator—zander (Sander lucioperca)—by olfactory cues and adapt accordingly. Over a period of 30 days, Baltic sturgeons were supplied with effluent water from a rearing tank with zander (zander unit) and, as a control, carp (carp unit), three tanks each. Distribution within the tank, morphology of the dorsal scutes, stress (glucose, lactate and cortisol) and gene expression of brain plasticity and cognition were studied in comparison to the control group (carp unit). No significant differences between the zander and the carp unit were observed in any of the parameters measured. Thus, we conclude that naïve Baltic sturgeon is not able to innately recognize potential predators by olfaction alone. Therefore, future studies should focus on applying predator odor together with chemical alarm substances.     

Morphology and ultrastructure of Siberian sturgeon (Acipenser baerii) spermatozoa using scanning and transmission electron microscopy

BACKGROUND INFORMATION: Available data concerning the sperm morphology of teleost fishes demonstrate wide variation. In the present study, the spermatozoa of Siberian sturgeon (Acipenser baerii Brandt, 1869), a chondrostean fish, was investigated. In contrast with teleost fish, chondrostean spermatozoa have a head with a distinct acrosome, whereas other structures, such as a midpiece and a single flagellum, are present in spermatozoa of most species. RESULTS: The average length of the head including the acrosome and the midpiece was 7.01+/-0.83 microm. Ten posterolateral projections derived from the acrosome were present on a subacrosomal region, with mean lengths of 0.94+/-0.15 microm and widths of 0.93+/-0.11 microm. The nucleus consisted of electrodense homogeneous nuclear chromatin. Three intertwining endonuclear canals, bound by membranes, traversed the nucleus longitudinally from the acrosomal end to the basal nuclear fossa region. There were between three and six mitochondria, two types of centrioles (proximal and distal) in the midpiece and two vacuoles composed of lipid droplets. The flagellum (44.75+/-4.93 microm in length), originating from the centriolar apparatus, had a typical 9+2 eukaryotic flagellar organization. In addition, there was an extracellular cytoplasm canal between the cytoplasmic sheath and the flagellum. CONCLUSIONS: A principal components analysis explained the individual morphological variation fairly well. Of the total accumulated variance, 41.45% was accounted for by parameters related to the head and midpiece of the sperm and the length of the flagellum. Comparing the present study with previous studies of morphology of sturgeon spermatozoa, there were large inter- or intra-specific differences that could be valuable taxonomically.     

Balbiani cytoplasm in oocytes of a primitive fish,the sturgeon <Emphasis Type="Italic">Acipenser gueldenstaedtii</Emphasis>, and its potential homology to the Balbiani body (mitochondrial cloud) of <Emphasis Type="Italic">Xenopus laevis</Emphasis> oocytes

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. This work was supported by funds from the research grant BW/IZ/2005 to M.Z.