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1.
In 2013,a novel disease was detected in tilapia( Oreochromis niloticus × O.aureus) in Guangzhou,South China.To identify the causative pathogen,we conducted histological examination,bacteria isolation,and purification,and sequenced the 16 S rRNA gene of isolates.Infected fish had a large number of white granulomas in the kidney,liver,heart,and spleen.The head kidney and spleen were markedly swollen.A bacterium strain designated as gz201301 was recovered from the spleen of infected tilapia.The 16 S rRNA sequence of gz201301 revealed that it was highly similar to F.noatunensis subsp.orientalis.This is the first report of a Francisella-like infection in farmed tilapia in China.  相似文献   

2.
In this study, Pearl oyster mantle type V collagen(POMC) and tilapia scale type I collagen(TSC) were extracted and hydrolyzed by various proteases in order to obtain peptides. The antioxidant activity of the peptides was investigated by DPPH, hydroxyl radical scavenging experiments and a dynamic digestion model in vitro. The results show that there are significant differences in amino acid composition between POMC and TSC. The collagen peptides obtained from pearl oyster mantle(POMCP) by treating with alkaline protease exhibited higher antioxidant activity than that from tilapia scale(TSCP) treated with papaya protease, and both of them showed greater DPPH and hydroxyl radical scavenging activity than other peptides. After being separated via Sephadex G-25 chromatography, the M1 fraction isolated from POMCP, and the S1 fraction from TSCP with which both had higher molecular weights showed the strongest antioxidant activity than other fractions, and the M1 fraction exhibited stronger antioxidant activity than the S1 fraction in scavenging free-radicals and protecting cells from the oxidation damage. Furthermore, after treating the dynamic digestion system model in vitro, the DPPH and hydroxyl radical scavenging activity of the M1 fraction increased slightly. These results suggest that POMCP exhibits stronger antioxidant activity than TSCP, which means that PMOP may be a good candidate to be a potential natural antioxidant in the food-processing industry.  相似文献   

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1 INTRODUCTION Compensatory growth or catch-up growth is a phase of unusual rapid growth induced by a period of environmental restriction; it had been demon-strated in a wide range of fish species following food deprivation (Bilton and Robins, 1973; Dobson and Holmes, 1984; Miglavs and Jobling, 1989; Quinton and Blake, 990; Wieser et al., 1992; Reim-ers et al., 1993; Kim and Lovell, 1995; Paul et al., 1995), restricted feeding (Weatherley and Gill, 1981; Jobling and Koskela, 1996; P…  相似文献   

4.
通过测定喂食水华微囊藻的尼罗罗非鱼胃PH值、不同颜色粪便的叶綠素/脱镁叶綠素比例,发现尼罗罗非鱼具有一个与摄食相关的胃酸分泌周期。摄食旺期胃平均PH值为1.47,最低值为0.8。停食后PH值升高,最大值为6.0。用不同浓度的盐酸处理水华微囊藻和对不同颜色粪便的营养分析结果表明,高浓度的胃酸(PH<2)溶解了水华微囊藻细胞壁,为肠消化酶对细胞内含物进行消化创造了先决条件。  相似文献   

5.
Parametamorphic rocks from Arong County in southeastern Inner Mongolia- Daxinganling district are regarded as Proterozoic in age, belonging to the Wolegen Group and composed of volcanoclastic and sand- stone in origin, and have been disputed in tectonic setting. Because of the stability in metamorphism, the rare earth elements indicate the features of their protoliths. The authors integrated the petrologic methods with the geochemical parameters which include ЕREE, ЕLREE/NHREE, δCe, δEu, La/Yb, Sm/Nd, Th/Sc and the standard values of chondrite. The results show that the protoliths of Wolengen Group may be a group of volcanoclastic and continental margin clastic rocks, and their tectonic setting is the continent island arc.  相似文献   

6.
The aim of the investigation is to reveal possible causes of isolation and co-occurrence of the economically significant concentrations of gold and tin. Comparative analysis of the different-rank factors that influenced migration and concentration of these elements show that different geochemical properties of Au and Sn are responsible for isolation of their big concentrations giving rise to independent metallogenic provinces, zones, and ore nodes. These differences resulted in individualization of the element migration ways to the level of ore concentration within the fluid-magmatic columns. Three main factors influenced the Au and Sn migration activity: different patterns of metal connection with the melt structure, different relation with oxygen, and different relation with other strong oxidizers. By the moment when ore-bearing fluid became isolated from magmas, the metallogenic signature of the melts, contrasting in redox-potential, had already been defined that was confirmed by the fact that tin ores associate predominantly with the granitoids of ilmenite series and gold ores with those of magnetite series. The fluid-magmatic systemswith an intermediate degree of the melt reduction-oxidation may be considered the potential producers of the combined metal concentrations. In these cases, the combined concentrating of tin and gold is plagued by an opposite direction of the oxidation-reduction reactions when their most common minerals are formed: the main migration form of Sn+2 must be oxidized (with cassiterite portioning) , and the forms of Au+ or Au+3 must be reduced (with native gold portioning) . Probably, because of this the combined tin and gold concentrations are dominated by one of the metals with a tendency of accumulation in different-stage mineral complexes.  相似文献   

7.
To study the bioactive metabolites produced by sponge-derived uncultured symbionts, a metagenomic DNA library of the symbionts of sponge Gelliodes gracilis was constructed. The average size of DNA inserts in the library was 20 kb. This library was screened for antibiotic activity using paper disc assaying. Two clones displayed the antibacterial activity against Micrococcus tetragenus. The metabolites of these two clones were analyzed through HPLC. The result showed that their metabolites were quite different from those of the host E. coli DH5α and the host containing vector pHZ132. This study may present a new approach to exploring bioactive metabolites of sponge symbionts.  相似文献   

8.
Based on experiment data of the Sino-German comprehensive investigations in the Bohai Sea in 1998 and 1999, a simple coupled pelagic-benthic ecosystem multi-box model is used to simulate the ecosystem seasonal variation. The pelagic sub-model consists of seven state variables: phytoplankton, zooplankton, TIN, TIP, DOC, POC and dissolved oxygen (DO). The benthic sub-model includes macro-benthos, meiobenthos, bacteria, detritus, TIN and TIP in the sediment. Besides the effects of solar radiation, water temperature and the nutrient from sea bottom exudation, land-based inputs are considered. The impact of the advection terms between the boxes is also considered. Meanwhile, the effects of the micro- bial-loop are introduced with a simple parameterization. The seasonal variations and the horizontal distributions of the ecosystem state variables of the Bohai Sea are simulated. Compared with the observations, the results of the multi-box model are reasonable. The modeled results show that about 13% of the photosynthesis primary production goes to the main food loop, 20% transfers to the benthic domain, 44% is consumed by the respiration of phytoplankton, and the rest goes to DOC. Model results also show the importance of the microbial food loop in the ecosystem of the Bohai Sea, and its contribution to the annual zooplankton production can be 60%-64%.  相似文献   

9.
The changes of taxonomical composition of the Late Jurassic-Early Cretaceous palynofloras are revealed,in the upper stream of Bureya River in Bureya Basin.The palynofloras are dominated as follows:the Berriasian one by ferns(Cyatheaceae,Dicksoniaceae,Osmundaceae),Classopollis and bisaccate pollen;the Valanginian-Hauterivian one by ferns(Cyatheaceae,Dicksoniaceae),Ginkgocycadophytus and bisaccate pollen;the Barremian one by ferns(Cyatheaceae,Dicksoniaceae);the Aptian one by ferns(Cyatheaceae,Dicksoniaceae,Gleicheniaceae) and Ginkgocycadophytus;and the Albian one by ferns(Schizaeaceae) and bisaccate pollen.In the Albian the floral diversity raises with the angiosperms appearing.  相似文献   

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The study on the earthquake-resistant performance of a pile-soil-structure interaction system is a relatively complicated and primarily important issue in civil engineering practice. In this paper, a computational model and computation procedures for pile-supported structures, which can duly consider the pile-soil interaction effect, arc established by the finite clement method. Numerical implementation is made in the time domain. A simplified approximation for the seismic response analysis of pile-soil-structure systems is briefly presented. Then a comparative study is performed for an engineering example with numerical results computed respectively by the finite clement method and the simplified method. Through comparative analysis, it is shown that the results obtained by the simplified method well agree with those achieved by the finite element method. The numerical results and findings will offer instructive guidelines for earthquake-resistant analysis and design of pile-supported structures.  相似文献   

12.
To use the water resources reasonably in the midstream of Yinma River is of great significance to Changchun City which is short of water. With the runoff data of physical measuring, the paper analyses the characteristics surface rtmoff of the area, by means of the groundwater flow numerical simulation, and represents the characteristics of the groundwater runoff in the area. Based on combination analyses of the two runoffs, the authors point out the problem of the water resources use in this area and bring forward a resolution of conjunctive regulation and storage of the surface water and groundwater.  相似文献   

13.
1 Introduction The industrial location is always the focus in academic circles and any analysis on industrial location can not avoid the agglomeration mechanism formed as the result of the industrial location. The study on the industrial location has become the focus for the massive theoretical location problems about agglomeration since the 1970s, which has a great influence on the formation of the in- dustrial location. In order to make more study of its in- fluence, it is necessary to resea…  相似文献   

14.
As a very important component of a coastal system,tidal flats come to be a focus of the studies on land-ocean interaction in the coastal zone because those areas are subjected to intense human activities and are highly sensitive to the global change.The Quanzhou Bay,located along the middle part of Fujian coast of China,covers about 136.4km2,and the area of coastal wetland in the entire bay from intertidal to subtidal with 6m of water depth accounts for 96% of the total area.Seven short cores were collected and divided in situ with the interval of 5cm on the coastal wetlands of Quanzhou Bay on April 19,2006.The sediment samples were scattered and the grain sizes were measured by using Mastersizer 2000.Human beings' activities on tidal flat have disturbed the vertical distribution of sediments in stratigraphic sequence and accelerated the sedimentation rates.Grain size analysis results show that the grain size diameters increase and sediment becomes worse sorted towards the sea under the strong human disturbance;Spartina alterniflora can play a role of trapping the fine sediment;but near the bank,the sediment becomes coarse and there are two peak values on frequency curve influenced by the sandpile.The trough formed by human activities along the coastline changes the transport path of water and suspended sediment.The sediments are transported through the trough and deposit in it during the flood;the ebb flow is retarded by the flow output through the adjacent trough,and the deposited sediment can not be re-suspended;then,the sedimentation rate increases.In situ observation show that the sedimentation rate is about 8-10cm/yr.  相似文献   

15.
The changes of taxonomical composition of the Late Jurassic- Early Cretaceous palynofloras are revealed, in the upper stream of Bureya River in Bureya Basin. The palynofloras are dominated as follows: the Berriasian one by ferns (Cyatheaceae, Dicksoniaceae, Osmundaceae), Classopollis and bisaccate pollen; the Valanginiar-Hauterivian one by ferns (Cyatheaceae, Dicksoniaceae), Ginkgocycadophytus and bisaccate pollen; the Barremian one by ferns (Cyatheaceae, Dicksoniaceae); the Aptian one by ferns (Cyatheaceae, Dicksoniaceae, Gleicheniaceae) and Ginkgocycadophytus; and the Albian one by ferns (Schizaeaceae) and bisaccate pollen. In the Albian the floral diversity raises with the angiosperms appearing.  相似文献   

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The grounded theory of qualitative methods was applied to researching the social integration of tourism labor migrants in the Jiuhua Mountain of Anhui Province, China. The research was conducted based on the in-depth interviewing of 15 samples, open-consultation and the analysis of secondhand data. The integration models of tourism labor migrants in the Jiuhua Mountain were formed through four processes including theoretic sampling, coding-analysis, cross-tabulation and contextualization. The result shows that modes of production and life styles decide self-integration orientation of tourism labor migrants in the Jiuhua Mountain. Cultural differences are fundamental dissimilarity between tourism labor migrants and natives. There are three kinds of integration models including rapid, free and gradually advancing integration. The differences among different types of migrants' integration models are remarkable. Taking the working integration as the abscissa and taking the life integration as the coordinate, an "S" model of integration matrix appears in the gradually advancing integration of intermediate and high administers from the working to the life which should be paid special attention to.  相似文献   

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20.
Our study group has developed a unique combined ters from the industries of dyestuff, pharmaceutical, chemical biological technology to treat high-strength organic wastewaengineering and zymolysis by using the principles of anaerobic ecological niche and bio-phase separation. The study obtained five national invention patents and eight patent equipments. This technology contains four kernel processes - two-phase anaerobic-aerobic process, hydrolysis-acidification-oxidation process, UASBAF-oxidation process, and internal cycling-hydrolysis-oxidation process. Fifteen pilot projects were accomplished in the basins of Tai Lake, Huai River, Liao River and Songhua River, and their total capital investment reached 185.214 million Yuan (RMB). Compared to conventional wastewater treatment technology, the innovative technology is more costeffective for high-strength organic wastewater treatment, can save capital investment by 15% - 30%, lessen land usage by 20% to 40% and decrease the operating cost by 10% to 25%. The operating cost of treatment per cubic meter industrial wastewater could be below 0.6 to 1.4 Yuan (RMB).  相似文献   

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