壳聚糖酶基因在解脂耶氏酵母中的表达及重组酶性质研究   总被引：1，自引：0，他引：1  

刘万顺  王娇  杨艳  韩宝芹  董文  刘光磊  池振明 《中国海洋大学学报(自然科学版)》2011,41(12):58-62

为构建高效表达壳聚糖酶工程菌株,以Microbacteriumsp.基因组为模板扩增壳聚糖酶基因,目的基因与表达载体pINA1317连接构建重组质粒,重组质粒NotⅠ酶切线性化后转化解脂耶氏酵母Y.liPolytica Po1h。所得结果为PCR扩增得到约1000bp的特异性片段,序列分析表明含有壳聚糖酶全长基因,开放阅读框801bp,编码266个氨基酸残基。转化子酶活力为10.4U/mL,是原菌株酶活力的3.15倍。重组蛋白经DEAE-Sepharose FF分离纯化,达到电泳纯,SDS-PAGE显示单一条带,分子量约41kDa。重组酶反应最适温度为45℃,最适pH为5.6,Km和Vmax分别是0.926mg/mL和6.15U/mL。质谱分析酶解产物主要为三糖和五糖。实现了壳聚糖酶在解脂耶氏酵母中的分泌表达,为壳聚糖酶的工业化生产奠定了理论基础。  相似文献   

渤海湾西岸潮间带现代沉积速率研究   总被引：8，自引：3，他引：8  

孟伟  雷坤  郑丙辉  王福  王宏  李建芬  李勇 《海洋学报》2005,27(3):67-72

利用渤海湾西岸潮间带柱状沉积物的210Pb_ex和137Cs活度测定结果,计算了潮间带现代沉积物的平均沉积速率,结果表明,渤海湾西岸潮间带砂质区(道沟子至独流减河)1955～1963年的沉积速率为3.43～4.06cm/a,1963年以来的平均沉积速率为0.65～1.59cm/a;泥质区(歧口附近)的平均沉积速率约为1.81cm/a.上述结果说明潮间带砂质区在20世纪50～60年代发生快速沉积作用,60年代之后沉积作用变缓.这可能是由于华北地区在该时段具有丰沛的降水和入海水沙,为潮间带沉积物提供了丰富的物源.60年代以后沉积作用变缓可能是自然和人类活动引起的入海水量减少和由此导致的物源减少的结果.  相似文献   

海洋气团对沿海城市大气环境影响与识别研究     

石红旗  王霄曈  张昊阳  石博欣  张睿 《海洋科学》2018,42(12):100-108

本研究通过识别海洋气团特征及沿海城市大气受到海洋气团的影响方式与程度,为评价沿海城市空气环境质量提供科学依据。以青岛市为例,收集大气气溶胶样品中放射性核素~(210)Pb、40K数据及采集时段当地大气颗粒物数据;分析~(210)Pb活度浓度与气溶胶颗粒物浓度变化;对当地当时大气气团进行溯源分析。研究表明:(1)研究期间青岛沿岸地区2015年4月至2016年6月与2016年6月至2017年6月大气污染特征显著不同,前者~(210)Pb活度浓度与污染颗粒物浓度显著相关,而后者~(210)Pb活度浓度与污染颗粒物无相关关系;(2)穿越海洋的陆地气团呈现出高活度浓度、低颗粒物浓度的特征;来自海洋气团的气溶胶呈现出低活度浓度、低颗粒物浓度的特征;(3)海洋气团气溶胶中~(210)Pb活度浓度较低。临近大陆的海洋(黄海、东海)上层大气受到大陆气团的影响,其海洋气团的特征有所减弱。~(210)Pb活度浓度、颗粒物浓度(PM2.5)可作为判断海洋气团的指标,识别"来自海洋的气团"与"经过海洋的气团"。  相似文献   

山东半岛近岸海区现代沉积速率分析   总被引：1，自引：0，他引：1  

张荣敏  张桂林  黄博  张宪军 《海洋地质前沿》2009,25(9):15-18

对山东半岛南北两侧的6个沉积物柱状样岩心进行了^210Pb测定,绘制出了^210Pb活度垂向分布图。YZ5中^210Pb垂向分布具有混合层、衰变层、平衡层三段式特点;YZ26、YZ33在0～6cm段^210Pb呈现倒置式,6cm以下具有显著的衰变层和平衡层;YZ14、YZ38中^210Pb表现为只具有衰变层和平衡层的二段式;YZ21中^210Pb表现为一段式,从表层到底层的扎。Pb活度衰变数值均一。YZ5、YZ14、YZ38、YZ33四站的沉积速率分别为0．418cm／a、0．757cm／a、0．326cm／a、0．338cm／a,属于中高速沉积区;YZ26的沉积速率为0．159cm／a,属于低速沉积区;YZ21的沉积速率很低。结合有关资料,对影响沉积速率的主要因素进行了简要探讨分析。  相似文献   

STUDY ON ~(210) Po IN MARINE ORGANISMS IN NORTH CHINA WATERS     

邹本川  秦学祥 《中国海洋湖沼学报》1999,(4)

INTRODUCTIONWiththedevelopmentofcoastalnuclearpowerandmarinenuclearestablishments,peoplepaymoreandmoreattentiontothedistribution ,behaviorandpathwaysofsomeman maderadionuclidesinmarineenvironment.Thedischargedartificialradionuclidesoverlieabackgroundofnaturallyoccurringradionu clideswhicheitheralreadyexistedinmarineenvironmentorwasenhancedbysomeotherhumanactivi ties.Goodunderstandingofsomeman incurredradionuclides’impactsonpeopleandmarineorganismsrequiresknowledgeofsomecriticalnaturalradi…  相似文献   

Radiometric dating of lake sediments from Signy Island (maritime Antarctic): evidence of recent climatic change   总被引：4，自引：0，他引：4  

P. G. Appleby  V. J. Jones  J. C. Ellis-Evans 《Journal of Paleolimnology》1995,13(2):179-191

Sediment cores from three lakes (Moss, Sombre and Heywood) in the maritime Antarctic (Signy Island, South Orkney Islands) have been successfully dated radiometrically by²¹⁰Pb and¹³⁷Cs. The core inventories of both fallout radionuclides are an order of magnitude higher than that which can be supported by the direct atmospheric flux at this latitude. The elevated values may be explained by fallout onto the catchment during the winter being delivered directly to the lakes during the annual thaw. Two of the lakes (Sombre and Heywood) show marked increases in sediment accumulation afterc. 1950. This appears to be associated with a documented rise in temperature in the South Orkney Islands, which has caused extensive deglaciation at Signy Island.This is the tenth of a series of papers to be published by this journal following the 20 ^th anniversary of the first application of²¹⁰Pb dating of lake sediments. Dr P.G. Appleby is guest editing this series.  相似文献   

Nitrogen and sulfur species in Antarctic aerosols at Mawson,Palmer Station,and Marsh (King George Island)   总被引：4，自引：0，他引：4  

D. L. Savoie  J. M. Prospero  R. J. Larsen  F. Huang  M. A. Izaguirre  T. Huang  T. H. Snowdon  L. Custals  C. G. Sanderson 《Journal of Atmospheric Chemistry》1993,17(2):95-122

High volume bulk aerosol samples were collected continuously at three Antarctic sites: Mawson (67.60° S, 62.50° E) from 20 February 1987 to 6 January 1992; Palmer Station (64.77° S, 64.06° W) from 3 April 1990 to 15 June 1991; and Marsh (62.18° S, 58.30° W) from 28 March 1990, to 1 May 1991. All samples were analyzed for Na⁺, SO ₄ ^2– , NO ₃ ^– , methanesulfonate (MSA), NH ₄ ⁺ ,²¹⁰Pb, and⁷Be. At Mawson for which we have a multiple year data set, the annual mean concentration of each species sometimes vary significantly from one year to the next: Na⁺, 68–151 ng m^–3; NO ₃ ^– , 25–30 ng m^–3; nss SO ₄ ^2– , 81–97 ng m^–3; MSA, 19–28 ng m^–3; NH ₄ ⁺ , 16–21 ng m^–3;²¹⁰Pb, 0.75–0.86 fCi m^–3. Results from multiple variable regression of non-sea-salt (nss) SO ₄ ^2– with MSA and NO ₃ ^– as the independent variables indicates that, at Mawson, the nss SO ₄ ^2– /MSA ratio resulting from the oxidation of dimethylsulfide (DMS) is 2.80±0.13, about 13% lower than our earlier estimate (3.22) that was based on 2.5 years of data. A similar analysis indicates that the ratio at Palmer is about 40% lower, 1.71±0.10, and more comparable to previous results over the southern oceans. These results when combined with previously published data suggest that the differences in the ratio may reflect a more rapid loss of MSA relative to nss SO ₄ ^2– during transport over Antarctica from the oceanic source region. The mean²¹⁰Pb concentrations at Palmer and Marsh and the mean NO ₃ ^– concentration at Palmer are about a factor of two lower than those at Mawson. The²¹⁰Pb distributions are consistent with a²¹⁰Pb minimum in the marine boundary layer in the region of 40°–60° S. These features and the similar seasonalities of NO ₃ ^– and²¹⁰Pb at Mawson support the conclusion that the primary source regions for NO ₃ ^– are continental. In contrast, the mean concentrations of MSA, nss SO ₄ ^2– , and NH ₄ ⁺ at Palmer are all higher than those at Mawson: MSA by a factor of 2; nss SO ₄ ^2– by 10%; and NH ₄ ⁺ by more than 50%. However, the factor differences exhibit substantial seasonal variability; the largest differences generally occur during the austral summer when the concentrations of most of the species are highest. NH ₄ ⁺ /(nss SO ₄ ^2– +MSA) equivalent ratios indicate that NH₃ neutralizes about 60% of the sulfur acids during December at both Mawson and Palmer, but only about 30% at Mawson during February and March.  相似文献   

Distribution coefficients of210Pb and210Po in laboratory and natural aquatic systems     

K. Wang  R. J. Cornett 《Journal of Paleolimnology》1993,9(2):179-188

We have measured the distribution coefficient (Kd) of²¹⁰Po and²¹⁰Pb in laboratory systems and in natural freshwater systems. In the laboratory systems, an inverse relationship was observed between the particle concentration of sand or lake sediment, and the distribution coefficients of²¹⁰Po and²¹⁰Pb. The slope of the log-linearK _d vs particle concentration relation is consistent with existingK _d-particle concentration theories. These laboratory observations are consistent with similar measurements in two lakes. TheK _d values of Po and Pb for the bottom sediment-pore water system with a high particle concentration were 10 to 100 times lower than those for dilute concentrations of particles suspended in the lake water. TheK _d of²¹⁰Pb in the sediments was >10⁴ so that the diffusive transport of²¹⁰Pb has only a small influence on the interpretation of²¹⁰Pb concentration-depth profiles and the²¹⁰Pb dating of these sediments.This is the second of a series of papers to be published by this journal following the 20^th anniversary of the first application of²¹⁰Pb dating of lake sediments. Dr P. G. Appleby is guest editing.  相似文献   

How reliable is the210Pb dating method? Old and new results from Switzerland     

H. R. von Gunten  R. N. Moser 《Journal of Paleolimnology》1993,9(2):161-178

We present a historical overview of applications of²¹⁰Pb dating in Switzerland with a special emphasis on the work performed at the University of Bern. It is demonstrated that the average specific activity of²¹⁰Pb in the lower atmosphere is very constant and does not show seasonal variations. We then concentrate on new results from Lobsigensee, a very small lake, and on published and new data from Lake Zurich. Several²¹⁰Pb profiles from these lakes show obvious disturbances and a disagreement of the resulting sedimentation rate when compared to that for the 23 years defined by¹³⁷Cs peaks of 1986 (Chernobyl) and 1963 (bomb fallout).A mean sedimentation rate of about 0.14 g cm^–2 y^–1 is found in the oxic and suboxic center part of Lake Zurich. In the oxic locations, the²¹⁰Pb flux to the sediments was close to the atmospheric input of about 1/60 Bq cm^–2 y^–1. In other parts of the lake a significant deficit in the inventory of²¹⁰Pb was found in the sediments. This could be due to a chemical redissolution of²¹⁰Pb together with Mn under reducing conditions. In contrast, in the suboxic part of the lake (135 m depth) the flux of²¹⁰Pb was about twice the atmospheric input. This excess is not caused by allochthonous contributions and is tentatively explained by the transport of sediment material resulting from small slides at the very steep lake shores or more probably by reprecipitation of²¹⁰Pb together with Mn when the conditions in the lake water become locally and seasonally more oxidizing. Dissolved²¹⁰Pb may migrate from locations with reducing conditions and reprecipitate under more oxic conditions. Indeed, a correlation of Mn and²¹⁰Pb in sediments of Lake Zurich was found.This is the first of a series of papers to be published by this journal following the 20^th anniversary of the first application of²¹⁰Pb dating of lake sediments. Dr P. G. Appleby is guest editing this series.  相似文献   

Interpretation of210Pb profiles and verification of the CRS dating model in PIRLA project lake sediment cores     

Michael W. Binford  Jeffrey S. Kahl  Stephen A. Norton 《Journal of Paleolimnology》1993,9(3):275-296

This paper reports results and analysis of²¹⁰Pb-activity measurements in 51 lake-sediment cores from 32 lakes in the four PIRLA (Paleoecological Investigations of Recent Lake Acidification) project regions (Adirondack Mountains [New York], Northern New England, Northern Florida, and the Northern Great Lakes States). General application of the Constant Rate of Supply (Constant Flux) model for²¹⁰Pb dating is valid for lakes in the PIRLA study, although application of the model is equivocal in a few lakes.²¹⁰Pb inventories and profiles are replicable among closely spaced cores within a lake. Specific²¹⁰Pb activity in surface sediments is negatively correlated with bulk sediment accumulation rate in seepage lakes, but not in drainage lakes. Drainage lakes with lower pH have lower unsupported²¹⁰Pb inventories in sediments, but the relationship does not occur in seepage lakes.²¹⁰Pb profiles in only seven of the cores, all from either the Adirondacks or the northern Great Lakes states, exhibit exponential decay curves. Deviations from an exponential profile include a flattening of the profile in the top few cm or excursions of one or a few measurements away from an exponential curve.²¹⁰Pb dates typically agree with other chronostratigraphic markers, most of which are subject to greater uncertainty. Several hypotheses, including sediment mixing, hydrologic regime, sediment focusing, and acidification, are proposed to explain variation of²¹⁰Pb distribution among lakes and regions. Hydrologic factors exert control on unsupported²¹⁰Pb inventories in PIRLA lakes, and there is a strong focusing effect in drainage lakes but a weak focusing effect in seepage lakes.This is the third of a series of papers to be published by this journal following the 20^th anniversary of the first application of²¹⁰Pb dating of lake sediments. Dr P. G. Appleby is guest editing this series.  相似文献