A Comment on the Siberian, Acipenser baerii, and Russian, Acipenser gueldenstaedtii, Sturgeons

Contrary to the opinion of Kynard et al. (2002), the Siberian sturgeon, Acipenser baerii, does not belong to the Ponto-Caspian species. It inhabits Siberian rivers and Lake Baikal. Acipenser baerii is a typical potamodromous species and the comparison of the behavior of its embryos and larvae with those of the anadromous Russian sturgeon, Acipenser gueldenstaedtii, should be done with understanding that these species have different life histories. The statement by Kynard et al. (2002) that larvae of the Russian sturgeon do not migrate contradicts results of previous studies.     

史氏鲟Sox9基因cDNA的克隆及在早期发育过程不同组织中的表达

利用RT-PCR和RACE的方法从史氏鲟(Acipenser schrenchii)中克隆了Sox9基因cDNA的部分序列(1140bp)。组织特异性表达分析表明Sox9基因在1^ ～3^ 年龄史氏鲟的大脑、心脏、肝脏、眼睛、胰脏、肾脏、精巢和卵巢等8种组织中均有表达,只是表达量随发育阶段和组织的不同而稍有差异。刚孵出1日龄的史氏鲟鱼苗中Sox9微量表达,而孵出15日龄的鱼苗中表达量上升。1^ ～3^ 年龄的史氏鲟精巢和卵巢中Sox9基因均表达,说明Sox9基因在史氏鲟性别分化过程中所起的作用不明显。Sox9基因在史氏鲟不同发育时期的8种组织中广泛表达,这可能与Sox9基因在脊椎动物软骨分化过程中的功能保守性有关。     

Taxonomic Relations of Russian and Persian Sturgeons (genus Acipenser,Acipenseridae): an Updated Synthesis

Journal of Ichthyology - A comparative analysis of data on the morphological, genetic and ecological features of Russian, Persian and Colchic sturgeons was carried out in order to assess their...     

South Siberian plant species in the flora of Amur oblast and their conservation

Data on 24 South Siberian plants of the Amur oblast are listed with brief taxonomic, geographical, ecocenotic analyses. Problems of conservation of rare plant species are considered. It is proposed to establish two regional refuges in the Amur Basin for the conservation of South Siberian steppe species included in the Red List.     

Diversity of Lactic Acid Bacteria Associated with Fish and the Fish Farm Environment, Established by Amplified rRNA Gene Restriction Analysis

Lactic acid bacteria have become a major source of concern for aquaculture in recent decades. In addition to true pathogenic species of worldwide significance, such as Streptococcus iniae and Lactococcus garvieae, several species have been reported to produce occasional fish mortalities in limited geographic areas, and many unidentifiable or ill-defined isolates are regularly isolated from fish or fish products. To clarify the nature and prevalence of different fish-associated bacteria belonging to the lactic acid bacterium group, a collection of 57 isolates of different origins was studied and compared with a set of 22 type strains, using amplified rRNA gene restriction analysis (ARDRA). Twelve distinct clusters were delineated on the basis of ARDRA profiles and were confirmed by sequencing of sodA and 16S rRNA genes. These clusters included the following: Lactococcus raffinolactis, L. garvieae, Lactococcus l., S. iniae, S. dysgalactiae, S. parauberis, S. agalactiae, Carnobacterium spp., the Enterococcus “faecium” group, a heterogeneous Enterococcus-like cluster comprising indiscernible representatives of Vagococcus fluvialis or the recently recognized V. carniphilus, V. salmoninarum, and Aerococcus spp. Interestingly, the L. lactis and L. raffinolactis clusters appeared to include many commensals of fish, so opportunistic infections caused by these species cannot be disregarded. The significance for fish populations and fish food processing of three or four genetic clusters of uncertain or complex definition, namely, Aerococcus and Enterococcus clusters, should be established more accurately.     

Heterogeneity and Polymorphism of Functionally Specialized Blood Proteins of Migratory Fish on the Example of the North Caspian Population of Russian Sturgeons during the Sea and River Periods of Life. 2. Hemoglobins

We carried out comparative studies of the heterogeneity and polymorphism of the most important functionally specialized blood proteins, hemoglobins. The fractional composition of hemoglobin proved to be identical during the sea and river periods of life for all main parameters (number of components, relative mobility, and protein content of each component). This puts the Russian sturgeon in a special position with reference to migratory teleostean fish, specifically salmonids, in which the specific weight of the protein of slow and fast hemoglobins undergoes changes upon change of the habitat.     

Assessing the Risk of Hydroxybenzene Contamination in Fish Raised on a Chinese Aquaculture Farm

We estimated the risk posed by hydroxybenzene in farm-raised Crucian carps (Carassius carassius) from a pond on a fish farm in Beijing, China, by analyzing a time-series of observed hydroxybenzene concentrations in fish within a culturing season in year 2006. We used the basic linear regression to model the data and forecast the probability of hydroxybenzene concentration in pond fish exceeding selected health effect criteria (the risk) using Monte Carlo simulation. The risk is highly correlated with the time a fish stays in the pond. The results indicate that the risk–days in pond relationship resembles a sigmoid function with an inflection point around 150 days. The resulting model can be used to demonstrate the benefit of improving water quality in terms of increased fish production.     

The Species Composition and Distribution of Fish and Prawn in the Bed of the Lower Amur River

Russian Journal of Marine Biology - The distribution of fish and prawn in the bed of the lower Amur River (within 40–960 km from the mouth) is described based on the results of a beam-trawl...     

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.     

Bacterial Counts and Quality of Iced Fish Retailed at a Lusaka Market, Zambia

S ummary . The counts of total viable, coliform, streptococcal and sulphite reducing anaerobic bacteria and the presence of salmonellae were determined on 134 iced fish obtained from Luburma Market, Lusaka, Zambia, during June-December 1970. The quality of the uncooked fish was also assessed by appearance and odour. The purpose of these determinations was to obtain a picture of the variations of the bacterial counts in relation to season, origin, fish species and market quality. Total viable and coliform counts were of the order of millions and tens of thousands/cm² of skin surface, respectively. Higher counts were obtained in the hot season during September-October but with little change in appearance of the fish. There was a significant correlation ( P < 0·01) of both total viable and coliform bacteria with quality scores. A maximum permissible level of 10⁷ cells/cm² of skin surface was proposed for total viable counts and 10⁵/cm² for coliform bacteria, for iced fish of acceptable quality in Zambia.     

Correlation of eustatic and biotic events in the Ordovician paleobasins of the Siberian and Russian platforms

Nine sedimentary sequences are recognized in the Ordovician of the Siberian Platform. These sequences correspond to sea level fluctuations of the 3rd order, from 1 to 6 My. Correlation with the sequences recognized in the Ordovician of the Russian Platform suggest their possible eustatic nature. Cold water nontropical carbonates are suggested in the Ordovician of the Tungus Syneclise, which may be explained by the upwelling of cold oceanic waters. The upwelling was caused by re-distribution of oceanic currents due to largescale tectonic events in the mid-Ordovician. The Ordovician evolution of the Siberian Platform was much more similar to that of the North American Platform than of the Russian Platform.     

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.     

Development of the skull and pectoral girdle in Siberian sturgeon,Acipenser baerii,and Russian sturgeon,Acipenser gueldenstaedtii (Acipenseriformes: Acipenseridae)

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.     

吉林珲春自然保护区东北虎和东北豹及其有蹄类猎物的多度与分布

珲春国家级自然保护区是东北虎(Panthera tigris altaica)、东北豹(Panthera pardus orientalis)等濒危物种在中国的核心分布区。为了探究该区域野生动物的多度水平和空间分布, 了解人类干扰情况, 我们运用相对多度指数(relative abundance index, RAI)分析了2013年4-6月设置于此的83个红外相机位点的监测数据。红外相机的总捕获天数6,060 d, 共捕获10科18种野生哺乳动物, 其中鼬科4种, 猫科动物3种, 犬科、鹿科和松鼠科各2种, 猪科、熊科、麝科、猬科和兔科各1种。研究期间共拍摄到东北虎11只个体, 东北豹13只个体。从相对多度指数来看, 东北虎的相对多度(0.84)远高于东北豹(0.48), 它们的有蹄类猎物中梅花鹿(Cervus nippon)的相对多度最高(2.18), 其次为狍(Capreolus pygargus)(1.53)和野猪(Sus scrofa)(0.92)。人类活动和放牧的相对多度水平(分别为40.64和2.76)显著高于野生动物。在空间分布上, 东北虎和梅花鹿主要在保护区的核心区分布, 且与保护区社区共管区的多度水平差异显著, 而东北豹在不同功能区之间的分布差异不显著, 狍在保护区北部的多度水平较高, 但各功能区之间差异不显著, 野猪在社区共管区的多度水平显著高于核心区。可见, 核心区频繁的人类活动和放牧活动对野生动物的保护产生了影响, 未来应加强关于人类干扰对虎、豹种群及其有蹄类猎物的影响评估。     

Evidence of mitochondrial DNA clones of Siberian sturgeon, Acipenser baerii, within Russian sturgeon, Acipenser gueldenstaedtii, caught in the River Volga

Eleven of 34 sturgeons caught in the River Volga classified morphologically as Acipenser gueldenstaedtii were identified as Acipenser baerii from sequence analysis of the mitochondrial cytochrome- b gene. The Caspian Sea and its tributaries including the Volga are not native habitats of A. baerii . No A. baerii haplotype was observed in A. gueldenstaedtii from the Sea of Azov or the South Caspian Sea. Genetic contamination of A. gueldenstaedtii with A. baerii or A. baerii hybrids has occurred in the Volga. Crosses and backcrosses of these specimens with native A. gueldenstaedtii resulted in the loss of the morphological diagnostic A. baerii features. These findings are of special concern for conservation and management programmes, as well as for specimen identification for caviar trading control.     

Isolation of Multidrug-Resistant Stenotrophomonas maltophilia from Cultured Yellowtail (Seriola quinqueradiata) from a Marine Fish Farm

Six strains of multidrug-resistant Stenotrophomonas maltophilia were isolated from cultured yellowtail. The strains were divided into two clusters based on the 16S rRNA genes, and all of them contained L1 metallo-β-lactamase and L2 β-lactamase genes. Differences in the intercluster divergence between the lactamase genes suggest that horizontal transfer of the genes occurred.