Migration and isolation during the turbulent Ponto‐Caspian Pleistocene create high diversity in the crustacean Paramysis lacustris

The Ponto‐Caspian brackish‐water fauna inhabits estuaries and rivers of the Black, Azov and Caspian seas and is fragmented by higher salinity waters and a major interbasin watershed. The fauna is known for the high levels of endemism, complex zoogeographic histories, and as a recent source of successful invasive species. It remains debated whether the Black and Azov Sea brackish‐water populations survived unfavourable Pleistocene conditions in multiple separate refugia or whether the two seas were (repeatedly) recolonized from the Caspian. Using microsatellite and mtDNA markers, we demonstrate deep among‐ and within‐basin subdivisions in a widespread Ponto‐Caspian mysid crustacean Paramysis lacustris. Five genetic clusters were identified, but their relationships did not reflect the geography of the region. The Azov cluster was the most distinct (4–5% COI divergence), despite its geographic position in the corridor between Black and Caspian seas, and may represent a new species. In the northern Black Sea area, the Dnieper cluster was closer to the Caspian cluster than to the neighbouring Danube–Dniester–Bug populations, suggesting separate colonizations of the Black Sea. Overall, the data implied a predominant gene flow from the east to the Black Sea and highlight the importance of Caspian Sea transgressions in facilitating dispersal. Yet, the presence of distinct lineages in the Black Sea points to the persistence of isolated refugial populations that have gained diagnostic differences under presumably high mutation rates and large population sizes. The unfavourable Pleistocene periods in the Black Sea therefore appear to have promoted diversification of the brackish‐water lineages, rather than extirpated them.     

Ecophysiological properties of photosynthesizing bacteria from the Black Sea chemocline zone

In May 1998, during the fifty-first voyage on board the research vessel Professor Vodyanitskii, a comparative study was conducted of the species diversity of green and purple sulfur bacteria in the water column of the chemocline zone at deep-sea stations and on the bottom surface of the Black Sea shallow regions. At three deep-sea stations, the accumulation of photosynthesizing bacteria in the chemocline zone at a depth of 85-115 m was revealed on the basis of the distribution of potential values of carbon dioxide light fixation. The location of the site of potential carbon dioxide light fixation suggests that the photosynthesis may be determined by the activity of the brown Chlorobium sp., revealed earlier at these depths. Enrichment cultures of brown sulfur bacteria were obtained from samples taken at the deep-sea stations. By morphology, these bacteria, assigned to Chlorobium sp., appear as nonmotile straight or slightly curved rods 0.3-0.5 x 0.7-1.2 microm in size; sometimes, they form short chains. Ultrathin sections show photosynthesizing antenna-like structures, chlorosomes, typical of Chlorobiaceae. The cultures depended on the presence of NaCl (20 g/l) for growth, which corresponds to the mineralization of Black Sea water. The bacteria could grow photoautotrophically, utilizing sulfide, but the Black Sea strains grew much more slowly than the known species of brown sulfur bacteria isolated from saline or freshwater meromictic lakes. The best growth of the strains studied in this work occurred in media containing ethanol (0.5 g) or sodium acetate (1 g/l) and low amounts of sulfide (0.4 mM), which is consistent with the conditions of syntrophic growth with sulfidogens. The data obtained allow us to conclude that the cultures of brown sulfur bacteria are especially adapted to developing at large depths under conditions of electron donor deficiency owing to syntrophic development with sulfate reducers. The species composition of the photosynthetic bacteria developing in the bottom sediments of shallow stations differed substantially from that observed at deep-sea stations. Pure cultures of the green Chlorobium sp. BS 1C and BS 2C (chlorobactin as the carotenoid), purple sulfur bacteria Chromatium sp. BS 1Ch (containing spirilloxanthine series pigments), and Thiocapsa marina BS 2Tc (containing the carotenoid okenone) were obtained from samples of sediments at shallow-water stations. Brown sulfur bacteria were absent in the sediment samples obtained from the Black Sea shallow-water stations 1 and 2.     

Contemporary genetic structure and postglacial demographic history of the black scorpionfish,Scorpaena porcus,in the Mediterranean and the Black Seas

Understanding the distribution of genetic diversity in the light of past demographic events linked with climatic shifts will help to forecast evolutionary trajectories of ecosystems within the current context of climate change. In this study, mitochondrial sequences and microsatellite loci were analysed using traditional population genetic approaches together with Bayesian dating and the more recent approximate Bayesian computation scenario testing. The genetic structure and demographic history of a commercial fish, the black scorpionfish, Scorpaena porcus, was investigated throughout the Mediterranean and Black Seas. The results suggest that the species recently underwent population expansions, in both seas, likely concomitant with the warming period following the Last Glacial Maximum, 20 000 years ago. A weak contemporaneous genetic differentiation was identified between the Black Sea and the Mediterranean Sea. However, the genetic diversity was similar for populations of the two seas, suggesting a high number of colonizers entered the Black Sea during the interglacial period and/or the presence of a refugial population in the Black Sea during the glacial period. Finally, within seas, an east/west genetic differentiation in the Adriatic seems to prevail, whereas the Black Sea does not show any structured spatial genetic pattern of its population. Overall, these results suggest that the Black Sea is not that isolated from the Mediterranean, and both seas revealed similar evolutionary patterns related to climate change and changes in sea level.     

Effect of salinity on vegetative growth and sexual reproduction of algae from the genus <Emphasis Type="Italic">Ardissonea</Emphasis> de Notaris (Bacillariophyta)

Effect of salinity on vegetative growth and sexual reproduction was investigated in laboratory cultures of a benthic diatom Ardissonea crystallina (C. Agardh) Grunow from the Black Sea and vegetative growth of Ardissonea sp. from the coast of Martinique, the Atlantic Ocean. Typical water salinity in the places where the populations inhabit differs two times. It was shown that the clones of both populations have a broad tolerance and great ability to adapt to changes in salinity. Cells of different size (i.e., in different stages of the life cycle) responded differently to desalination. Salinities optimal for vegetative growth of these species were not the same. Ardissonea from the coast of Martinique was more sensitive to low levels of salinity as compared with A. crystallina from the Black Sea. It was surprising that salinity optimal for vegetative growth and sexual reproduction of the Black Sea species did not coincide with the real salinity level of the Black Sea. Position of physiological optimums indicates an oceanic (or Mediterranean) origin of the Black Sea population of A. crystallina.     

Activity dynamics of proteinases and glycosidases of fish chyme with exposure in fresh and brackish water

Activity of proteinases of the content of intestines (chyme) of the benthos-eater crucian carp Carassius carassius fed different diets during prolonged exposure to water is studied. In the process of exposure of the chyme to water, the activity of proteinases decreases. Activity of glycosidases may increase, maximally during the first three days of exposure. This phenomenon suggests the important role of enzymes of the enteral microflora in processes of destruction of protein and carbohydrate components of the suspension and especially of organic detritus.     

Domoic acid production by Pseudo-nitzschia calliantha Lundholm, Moestrup et Hasle (bacillariophyta) isolated from the Black Sea

A species of Pseudo-nitzschia isolated from Sevastopol Bay, Black Sea, was examined for its toxicity. The species was identified as P. calliantha Lundholm, Moestrup et Hasle based on SEM and TEM examination. Domoic acid (DA) was detected in batch culture throughout the growth cycle of P. calliantha. The production of DA by this diatom species was confirmed by fluorenylmethoxycarbonyl (FMOC) derivatization and HPLC-fluorescence method. The cellular DA level was higher in the early exponential phase, with the maximum value of 0.95 pg DA cell⁻¹. In the stationary phase, the cellular DA levels declined. This is the first record of a DA producing diatom isolated from the Black Sea.     

Detection of anaerobic sulfate-reducing bacteria in oxygen-containing upper water layers of the Black and Baltic Seas

Fluorescent in situ hybridization (FISH) and PCR were used for analysis of phylogenetic structure of anaerobic sulfate-reducing bacterial communities in oxygen-containing upper water layers of meromictic basins: the Black Sea and the Gdansk Deep of the Baltic Sea. In the Black Sea (continental slope at depths 30–70 m), cells of sulfate-reducing bacteria (SRB) hybridizing with 16S rRNA-specific FISH-probes for Desulfotomaculum, Desulfobacter, and Desulfovibrio genera were revealed, whereas Desulfomicrobium-related bacteria were prevalent in the chemocline zone at a 150-m depth. Besides Desulfotomaculum (SRB subgroup 1), Desulfobacter (SRB subgroup 4), and Desulfovibrio-Desulfomicrobium (SRB subgroup 6), nested PCR with the use of 16S rRNA gene-specific primers detected the presence of Desulfococcus–Desulfonema–Desulfosarcina (SRB subgroup 5) in the oxygen-containing water column of the Black and Baltic seas. Active enrichment SRB culture that contained bacterium Desulfosporosinus sp. as a major component was obtained from the Black Sea water sample collected at a 70-m depth.     

Black Sea algal viruses

Monitoring of the Black Sea algal viruses in Sevastopol bays and Crimean water areas has been carried out since 2002. Based on the methods that were developed and patented by the author, more than 200 strains of algal viruses of five species of microalgae that are new to science were isolated: TvV (Tetraselmis viridis virus), DvV (Dunaliella viridis virus), PtV (Phaeodactylum tricornutum virus), PpV (Prorocentrum pusillum virus) and IgV (Isochrysis galbana virus). For the first time in the Black Sea, the Emiliania huxleyi virus (EhV) of microalgae was isolated. Using the method of electron microscopy, the Black Sea algal viruses were identified as icosahedral virions with respective sizes of 56–60, 45–48, 50–53, 88–92, and 128–132 nm, for the TvV, PtV, DvV, PpV and IgV viruses. The EhV size, as determined by the method of filtration, was within the range of 50–200 nm. In the IgV and EhV viruses we revealed a viral envelope. Based on their characters the isolated algal viruses were attributed to the Phycodnaeviridae. The maximum number of algal viruses was observed in the spring and autumn seasons, which is typical for their host phytoplankton species. The Black Sea algal viruses, TvV, PpV, IgV, and EhV, displayed no strict species specificity and have a wide range of available hosts.     

Phylogeography of the planktonic chaetognath Sagitta setosa reveals isolation in European seas

Numerous planktonic species have disjunct distribution patterns in the world's oceans. However, it is unclear whether these are truly unconnected by gene flow, or whether they are composed of morphologically cryptic species. The marine planktonic chaetognath Sagitta setosa Müller has a discontinuous geographic distribution over the continental shelf in the northeastern Atlantic, Mediterranean Sea, and Black Sea. Morphological variation between these populations has been described, but overlaps and is therefore unsuitable to determine the degree of isolation between populations. To test whether disjunct populations are also genetically disjunct, we sequenced a 504-bp fragment of mitochondrial DNA comprising the cytochrome oxidase II region of 86 individuals. Sequences were highly variable; each represented a different haplotype. Within S. setosa, sequence divergence ranged from 0.2 to 8.1% and strong phylogeographic structure was found, with four main groups corresponding to the northeastern Atlantic, Mediterranean Sea (including Ligurian Sea, Tyrrhenian Sea and Gulf of Gabes), Adriatic Sea, and Black Sea. Two of these (Atlantic and Black Sea) were resolved as monophyletic clades, thus gene flow between disjunct populations of S. setosa has been extremely limited and lineage sorting has taken place. The deepest divergence was between Atlantic and Mediterranean/Black Sea populations followed by a split between Mediterranean and Black Sea populations. The Mediterranean/Black Sea clade comprised three groups, with the Adriatic Sea as the most likely sister clade of the Black Sea. These data are consistent with a colonization of the Black Sea from the Mediterranean. Furthermore, a possible cryptic species was found in the Black Sea with 23.1% sequence divergence from S. setosa. Two possibilities for the evolutionary origin of this species are proposed, namely, that it represents a relict species from the ancient Paratethys, or that it represents another chaetognath species that colonized the Black Sea more recently. Even though the exact timing of disjunction of S. setosa populations remains unclear, on the basis of the geological and paleoclimatic history of the European basins and our estimates of net nucleotide divergence, we suggest that disjunct populations arose through vicariance resulting from the cyclical changes in temperature and sea levels during the Pleistocene. We conclude that these populations have remained disjunct, not because of limited dispersal ability, but because of the inability to maintain viable populations in suboptimal, geographically intermediate areas.     

Specific features of the feeding of larval fish of the families Blenniidae and Gobiidae in relation to changes in the coastal plankton community of the Black Sea

Data on the feeding of larvae of mass Black Sea fish species of the families Blenniidae and Gobiidae with a length of 2.2–7.0 mm from coastal waters of the Crimea (Sevastopol) are presented. Despite the tendency for an improvement in the feeding of larval fish, Mnemiopsis leidyi, in the case of a prolonged staying in the plankton in mass amounts in the absence of Beroe ovata, exerts a negative effect on the food resources and the survival of larvae. This is evidenced by the indices of food consumption and the proportion of larvae with empty intestines.     

Biogeochemical cycle of methane in the northwestern shelf of the Black Sea

Seasonal investigations of methane distribution and rates of its oxidation and generation in the water column and sediments of the Black Sea northwestern shelf were carried out within the framework of the interdisciplinary projects "European River-Ocean Systems" (EROS-2000, EROS-21) and "Biogenic Gases Exchange in the Black Sea" (BigBlack) in August 1995, May 1997, and December 1999. Experiments that involved the addition of 14CH3COONa and 14CO2 to sediment samples showed the main part of methane to be formed from CO2. Maximum values of methane production (up to 559 mumol/(m2 day)) were found in coastal sediments in summer time. In winter and spring, methane production in the same sediments did not exceed 3.6-4.2 mumol/(m2 day). The delta 13C values of methane ranged from -70.7 to -81.8@1000, demonstrating its microbial origin and contradicting the concept of the migration of methane from cold seeps or from the oil fields located at the Black Sea shelf. Experiments that involved the addition of 14CH4 to water and sediment samples showed that a considerable part of methane is oxidized in the upper horizons of bottom sediments and in the water column. Nevertheless, it was found that, in summer, part of methane (from 6.8 to 320 mumol/(m2 day)) arrives in the atmosphere.     

一株产纤溶酶菌株的分离鉴定及其纤溶组分分析

【目的】筛选性能良好的产纤溶酶菌株,对菌株进行多项分类鉴定,分析其纤溶酶系的组成特征及纤溶能力。【方法】通过酪蛋白培养基初筛,琼脂-纤维蛋白双层平板复筛,从海泥、土壤等环境中筛选纤维蛋白降解菌,以尿激酶为标准测定纤溶酶活性。通过形态学、生理生化特征研究,结合16S rDNA基因序列分析菌株种类及系统分类地位。通过SDS-PAGE和纤维蛋白酶谱法分析胞外纤溶酶系的组成特征。【结果】筛选到一株能降解纤维蛋白的细菌CNY16,鉴定其为沙福芽孢杆菌(Bacillus safensis)。该酶为胞外酶,SDS-PAGE和纤维蛋白酶谱结果表明该纤溶酶系有至少两种分子量大小不同的纤溶酶,分别约33 kD和23 kD。能有效溶解血块中纤维蛋白,并且对红细胞无降解作用。【结论】细菌CNY16是一株新的纤溶酶产生菌,纤溶酶活性及稳定性较好,具有潜在开发价值。为获取新型纤溶酶提供了一种新的菌源。     

Posidonia oceanica in the Marmara Sea

The seagrass Posidonia oceanica is a stenohaline species endemic to the Mediterranean Sea, where it normally lives at a salinity of between 36.5 and 39.5 ppt. Surveys carried out at the North-eastern distribution limits revealed large beds in the Dardanelles Strait and isolated beds in the Marmara Sea, where the salinity ranges between 21.5 and 28 ppt. Microsatellite analysis of these low-salinity tolerant P. oceanica beds, show different signs of genetic isolation: excess of heterozygosity and a presence of fixed alleles. These particularities are rarely found in the whole distributional range of the species. Moreover, all the populations considered in the analysis have a very low genetic diversity in comparison with most of the meadows sampled throughout the Mediterranean Sea. Taking into consideration the genetic data, rhizome expansion rate and the actual extent of the isolated beds in the Marmara Sea and knowing the reproductive rate and dissemination characteristics of P. oceanica, we hypothesize that the isolated population of the Marmara Sea has been established since the Middle Holocene, before the catastrophic intrusion of brackish water into the Marmara Sea and the strong and persistent flow coming from the Black Sea.     

Isolation of parahemolytic vibrions from persons with acute gastrointestinal diseases]

Galophilic vibrios were for the first time in the Soviet Union isolated from the patients with gastrointestinal diseases in Novorossiisk during the summer-autumn period of 1973. The greatest number of strains of the parahemolytic vibrios was isolated in August and September, during intensive fishing season, from the patients in whom the disease usually developed 6 to 12 hours after eating the sea fish. The parahemolytic vibrios isolated from the patients were typical by all signs and produced a marked hemolysis on the Wagatsuma medium. The halophilic vibrios are inhabitants of the Black Sea. During the years of 1972-1973 there were isolated 109 strains of V. paraheamolyticus and 133 strains of V. alginolyticus from the sea water and various hydrobionts.     

Ecophysiological properties of photosynthetic bacteria from the Black Sea chemocline zone

In May 1998, during the fifty-first voyage on board the research vessel Professor Vodyanitskii, a comparative study was conducted of the species diversity of green and purple sulfur bacteria in the water column of the chemocline zone at deep-sea stations and on the bottom surface of the Black Sea shallow regions. At three deep-sea stations, the accumulation of photosynthetic bacteria in the chemocline zone at a depth of 85–115 m was revealed on the basis of the distribution of potential values of carbon dioxide light fixation. The location of the site of potential carbon dioxide light fixation suggests that the photosynthesis may be determined by the activity of the brown Chlorobium sp., earlier revealed at these depths. Enrichment cultures of brown sulfur bacteria were obtained from samples taken at the deep-sea stations. By morphology, these bacteria, assigned to Chlorobium sp., appear as nonmotile straight or slightly curved rods 0.3–0.5 × 0.7–1.2 µm in size; sometimes, they form short chains. Ultrathin sections show photosynthetic antenna-like structures, chlorosomes, typical of Chlorobiaceae. The cultures depended on the presence of NaCl (20 g/l) for growth, which corresponds to the mineralization of Black Sea water. The bacteria could grow photoautotrophically, utilizing sulfide, but the Black Sea strains grew much more slowly than the known species of brown sulfur bacteria isolated from saline or freshwater meromictic lakes. The best growth of the strains studied in this work occurred in media containing ethanol (0.5 g) or sodium acetate (1 g/l) and low amounts of sulfide (0.4 mM), which is consistent with the conditions of syntrophic growth with sulfidogens. The data obtained allow us to conclude that the cultures of brown sulfur bacteria are especially adapted to developing at large depths under conditions of electron donor deficiency owing to syntrophic development with sulfate reducers. The species composition of the photosynthetic bacteria developing in the bottom sediments of shallow stations differed substantially from that observed at deep-sea stations. Pure cultures of the green Chlorobium sp. BS 1C and BS 2C (chlorobactin as the carotenoid), purple sulfur bacteria Chromatium sp. BS 1Ch (containing spirilloxanthine series pigments), and Thiocapsa marina BS 2Tc (containing the carotenoid okenone) were obtained from samples of sediments at shallow-water stations. Brown sulfur bacteria were absent in the sediment samples obtained from the Black Sea shallow-water stations 1 and 2.__________Translated from Mikrobiologiya, Vol. 74, No. 2, 2005, pp. 239–247.Original Russian Text Copyright © 2005 by Gorlenko, Mikheev, Rusanov, Pimenov, Ivanov.     

Anaerobic methane oxidation and sulfate reduction in bacterial mats of coral-like carbonate structures in the Black Sea

A detailed study of the processes of anaerobic methane oxidation and sulfate reduction in the bacterial mats occurring on coral-like carbonate structures in the region of methane seeps in the Black Sea, as well as of the phenotypic diversity of sulfate-reducing bacteria developing in this zone, has been performed. The use of the radioisotopic method shows the microbial mat structure to be heterogeneous. The peak activity of the two processes was revealed when a mixture of the upper (dark) and underlying (intensely pink) layers was introduced into an incubation flask, which confirms the suggestion that methanotrophic archaea and sulfate-reducing bacteria closely interact in the process of anaerobic methane oxidation. Direct correlation between the rate of anaerobic methane oxidation and the methane and electron acceptor concentrations in the medium has been experimentally demonstrated. Several enrichment and two pure cultures of sulfate-reducing bacteria have been obtained from the near-bottom water and bacterial mats. Both strains were found to completely oxidize the substrates to CO2 and H2S. The bacteria grow at temperatures ranging from -1 to 18 (24) degrees C, with an optimum in the 10-18 degrees C range, and require the presence of 1.5-2.5% NaCl and 0.07-0.2% MgCl2 x 6H2O. Regarding the aggregate of their phenotypic characteristics (cell morphology, spectrum of growth substrates, the capacity for complete oxidation), the microorganisms isolated have no analogues among the psychrophilic sulfate-reducing bacteria already described. The results obtained demonstrate the wide distribution of psychrophilic sulfate-reducing bacteria in the near-bottom water and bacterial mats covering the coral-like carbonate structures occurring in the region of methane seeps in the Black Sea, as well as the considerable catabolic potential of this physiological group of psychrophilic anaerobes in deep-sea habitats.     

Diversity and abundance of sulfate-reducing microorganisms in the sulfate and methane zones of a marine sediment, Black Sea

The Black Sea, with its highly sulfidic water column, is the largest anoxic basin in the world. Within its sediments, the mineralization of organic matter occurs essentially through sulfate reduction and methanogenesis. In this study, the sulfate-reducing community was investigated in order to understand how these microorganisms are distributed relative to the chemical zonation: in the upper sulfate zone, at the sulfate-methane transition zone, and deeply within the methane zone. Total bacteria were quantified by real-time PCR of 16S rRNA genes whereas sulfate-reducing microorganisms (SRM) were quantified by targeting their metabolic key gene, the dissimilatory (bi)sulfite reductase (dsrA). Sulfate-reducing microorganisms were predominant in the sulfate zone but occurred also in the methane zone, relative proportion was maximal around the sulfate-methane transition, c. 30%, and equally high in the sulfate and methane zones, 5-10%. The dsrAB clone library from the sulfate-methane transition zone, showed mostly sequences affiliated with the Desulfobacteraceae. While, the dsrAB clone libraries from the upper, sulfate-rich zone and the deep, sulfate-poor zone were dominated by similar, novel deeply branching sequences which might represent Gram-positive spore-forming sulfate- and/or sulfite-reducing microorganisms. We thus hypothesize that terminal carbon mineralization in surface sediments of the Black Sea is largely due to the sulfate reduction activity of previously hidden SRM. Although these novel SRM were also abundant in sulfate-poor, methanogenic areas of the Black Sea sediment, their activities and possibly very versatile metabolic capabilities remain subject of further study.     

一株产纤溶酶菌株的分离、鉴定及其酶活特征的初步研究

[目的]分离筛选并鉴定产纤溶酶的菌株.[方法]采用血粉培养基富集,琼脂糖-纤维蛋白平板筛选,从自然界中分离筛选出一株产纤溶活性物质的菌株.通过形态学特征、生理生化特征研究,并结合16S rRNA基因序列分析及分子系统发育树的构建结果,确定菌株的种类.[结果]从自然界分离筛到一株产纤溶酶的菌株EF608,经鉴定该菌株为粪肠球菌(Enterococcus faecalis). SDS-PAGE和纤维蛋白自显影表明该纤溶酶的分子量为37 kD,最适反应温度和pH分别为35℃和7.5,EDTA能完全抑制其纤溶活性,而PMSF对其活性无抑制作用.菌株EF608发酵液不仅可以直接水解纤维蛋白,而且具有体外溶栓的作用,对血红细胞没有溶解作用.[结论]筛选到一株具有纤溶活性的粪肠球菌——EF608,为获取新型纤溶酶提供了一种的新的菌源.     

一株青藏高原冻土溶栓菌的筛选及鉴定

【目的】心脑血管疾病是一种世界性疾病,严重危害人类健康,溶栓酶是治疗该病的有效药物之一。而极端环境中的溶栓微生物因其特殊的生存方式,可能分泌高效、安全的新型溶栓酶。因此,为了获得这种具有特殊功能的溶栓酶,我们从青藏高原高海拔冻土中进行了溶栓菌的筛选。【方法】首先,本文通过血粉-琼脂平板初步筛选具有血粉水解功能的菌株,然后对其进行体外溶栓试验以检验其人工血栓溶解功能,并用纤维蛋白平板法测定其纤溶活性,最后通过生理生化试验和16S rRNA基因序列分析方法对该菌进行分类鉴定。【结果】本文从青海省玉树藏族自治州海拔4300 m的冻土样品中筛选获得了菌株DR-536,不仅具有水解血粉的功能,还具有体外溶栓功能,且能够水解纤维蛋白,纤溶活性为51.80 IU/mL(以尿激酶为标准)。最后,分类鉴定结果显示菌株DR-536是一株金黄节杆菌(Arthrobacter aurescens)。【结论】本文首次从青藏高原高海拔土壤中进行了溶栓菌的筛选,并获得了一株新型溶栓菌,为进一步研究和开发高效、安全的新型溶栓酶提供了菌源。     

Genetic and morphological analyses of tub gurnard Chelidonichthys lucerna populations in Turkish marine waters

Genetic and morphological structure of tub gurnard Chelidonichthys lucerna populations in Turkish marine waters were investigated with mtDNA sequencing of 16S rRNA and morphological characters. C. lucerna samples were collected from the Black Sea, Marmara, Aegean and northeastern Mediterranean coasts of Turkey. The lowest genetic diversity was found in the northeastern Mediterranean (Iskenderun Bay) population, while the highest was in the Marmara population with overall average value of genetic diversity within populations. A total of 14 haplotypes was found, and the highest haplotype diversity was in the Black Sea whereas the lowest was in the northeastern Mediterranean population (Iskenderun Bay). The Black Sea and Iskenderun Bay populations showed the least genetic divergence (0.001081), while the highest was between the Marmara Sea and northeastern Mediterranean (Antalya Bay) populations (0.002067). Pairwise comparisons of genetic distance revealed statistically significant differences (P < 0.05) between the Marmara and both the Aegean and northeastern Mediterranean (Antalya Bay) samples. Neighbour joining tree analyses clustered the northeastern Mediterranean populations (Antalya Bay and Iskenderun Bay) as genetically more interrelated populations, whereas the Aegean Sea population was clustered as most isolated one. Discriminant function analysis of morphological characters showed that only the Black Sea population is differentiated from the other populations.