Characterization of the artificially covalent conjugate of B-phycoerythrin and R-phycocyanin and the phycobilisome from Porphyridium cruentum

B-phycoerythrin (BPE) and R-phycocyanin (RPC) were purified from Porphyridium cruentum by Sephadex G-200 chromatography, then the BPE was attached covalently to the RPC by reacting their amino groups to form the artificially covalent BPE-RPC conjugate in which the excitation energy can transfer from the BPE to the RPC with low efficiency. Meanwhile, the intact phycobilisome (PBS) consisting of BPE, RPC, APC and L-CM was isolated and purified from Porphyridium cruentum, and the purified PBS was found to keep intact if the solution contains sucrose. Comparison of spectroscopic properties between the purified PBS and the BPE-RPC conjugate suggests that the BPE-RPC conjugate is much more stable than the purified PBS. The construction of BPE-RPC conjugate with low efficiency of the excitation energy transfer may be useful for preparing phycobiliprotein probes. (C) 2002 Elsevier Science Ireland Ltd. All rights reserved.

Construction of shuttle, expression vector of human tumor necrosis factor alpha (hTNF-alpha) gene and its expression in a cyanobacterium, Anabaena sp. PCC 7120

The construction of the shuttle, expression vector of human tumor necrosis factor alpha (hTNF-alpha) gene and its expression in a cyanobacterium Anabaena sp. PCC 7120 was reported. The 700-bp hTNF cDNA fragments have been recovered from plasmid pRL-rhTNF, then inserted downstream of the promoter PpsbA in the plasmid pRL439. The resultant intermediary plasmid pRL-TC has further been combined with the shuttle vector pDC-8 to get the shuttle, expression vector pDC-TNF. The expression of the rhTNF gene in Escherichia coil has been analyzed by SDS-PAGE and thin-layer scanning, and the results show that the expressed TNF protein with these two vectors is 16.9 percent (pRL-TC) and 15.0 percent (pDC-TNF) of the total proteins in the cells, respectively, while the expression level of TNF gene in plasmid pRL-rhTNF is only 11.8 percent. Combined with the participation of the conjugal and helper plasmids, pDC-TNF has been introduced into Anabaena sg PCC 7120 by triparental conjugative transfer, and the stable transgenic strains have been obtained. The existence of the introduced plasmid pDC-TNF in recombinant cyanobacterial cells has been demonstrated by the results of the agarose electrophoresis with the extracted plasmid samples and Southern blotting with alpha-(32)p labeled hTNF cDNA probes, while the expression of the hTNF gene in Anabaena sp. PCC 7120 has been confirmed by the results of Western blotting with extracted protein samples and human TNF-alpha monoclonal antibodies. The cytotoxicity assays using the mouse cancer cell line L929 proved the cytotoxicity of the TNF in the crude extracts from the transgenic cyanobacterium Anabaena sp. PCC 7120.

Isolation and mapping of telomeric pentanucleotide (TAACC)(n) repeats of the pacific whiteleg shrimp, Penaeus vannamei, using fluorescence in situ hybridization

To develop genetic and physical maps for shrimp, accurate information on the actual number of chromosomes and a large number of genetic markers is needed. Previous reports have shown two different chromosome numbers for the Pacific whiteleg shrimp, Penaeus vannamei, the most important penaeid shrimp species cultured in the Western hemisphere. Preliminary results obtained by direct sequencing of clones from a Sau3A-digested genomic library of P. vannamei ovary identified a large number of (TAACC/GGTTA)-containing SSRs. The objectives of this study were to (1) examine the frequency of (TAACC)(n) repeats in 662 P. vannamei genomic clones that were directly sequenced, and perform homology searches of these clones, (2) confirm the number of chromosomes in testis of P. vannamei, and (3) localize the TAACC repeats in P. vannamei chromosome spreads using fluorescence in situ hybridization (FISH). Results for objective I showed that 395 out of the 662 clones sequenced contained single or multiple SSRs with three or more repeat motifs, 199 of which contained variable tandem repeats of the pentanucleotide (TAACC/GGTTA),, with 3 to 14 copies per sequence. The frequency of (TAACC)n repeats in P. vannamei is 4.68 kb for SSRs with five or more repeat motifs. Sequence comparisons using the BLASTN nonredundant and expressed sequence tag (EST) databases indicated that most of the TAACC-containing clones were similar to either the core pentanucleotide repeat in PVPENTREP locus (GenBank accession no. X82619) or portions of 28S rRNA. Transposable elements (transposase for Tn1000 and reverse transcriptase family members), hypothetical or unnamed protein products, and genes of known function such as 18S and 28S rRNAs, heat shock protein 70, and thrombospondin were identified in non-TAACC-containing clones. For objective 2, the meiotic chromosome number of P. vannamei was confirmed as N = 44. For objective 3, four FISH probes (P1 to P4) containing different numbers of TAACC repeats produced positive signals on telomeres of P. vannamei chromosomes. A few chromosomes had positive signals interstitially. Probe signal strength and chromosome coverage differed in the general order of P1 > P2 > P3 > P4, which correlated with the length of TAACC repeats within the probes: 83, 66, 35, and 30 bp, respectively, suggesting that the TAACC repeats, and not the flanking sequences, produced the TAACC signals at chromosome ends and TAACC is likely the telomere sequence for P. vannamei.

A bioaugmentation failure caused by phage infection and weak biofilm formation ability

Two biological aerated filters (BAF) were setup for ammonia removal treatment of the circulation water in a marine aquaculture. One of the BAFs was bioaugmented with a heterotrophic nitrifying bacterium, Lutimonas sp. H10, where the ammonia removal was not improved and the massive inoculation was even followed by a nitrification breakdown from day 9 to 18. The nitrification was remained stable in control BAF operated under the same conditions. Fluorescent in situ hybridization (FISH) with rRNA-targeted probes and cultivable method revealed that Lutimonas sp. H10 almost disappeared from the bioaugomented BAF within 3 d, and this was mainly due to the infection of a specific phage as revealed by flask experiment, plaque assay and transmission electron observation. Analyses of 16S rRNA gene libraries showed that bacterial groups from two reactors evolved differently and an overgrowth of protozoa was observed in the bioaugmented BAR Therefore, phage infection and poor biofilm forming ability of the inoculated strain are the main reasons for bioaugmentation failure. In addition, gazing by protozoa of the bacteria might be the reason for the nitrification breakdown in bioaugmented BAF during day 9-18.

Characterization of eastern oyster (Crassostrea virginica Gmelin) chromosomes by fluorescence in situ hybridization with bacteriophage P1 clones

Chromosome identification is an essential step in genomic research, which so far has not been possible in oysters. We tested bacteriophage P1 clones for chromosomal identification in the eastern oyster Crassostrea virginica, using fluorescence in situ hybridization (FISH). P1 clones were labeled with digoxigenin-11-dUTP using nick translation. Hybridization was detected with fluorescein-isothiocyanate-labeled anti-digoxigenin antibodies and amplified with 2 layers of antibodies. Nine of the 21 P1 clones tested produced clear and consistent FISH signals when Cot-1 DNA was used as a blocking agent against repetitive sequences. Karyotypic analysis and cohybridization positively assigned the 9 P1 clones to 7 chromosomes. The remaining 3 chromosomes can be separated by size and arm ratio. Five of the 9 P1 clones were sequenced at both ends, providing sequence-tagged sites that can be used to integrate linkage and cytogenetic maps. One sequence is part of the bone morphogenetic protein type 1b receptor, a member of the transforming growth factor superfamily, and mapped to the telomeric region of the long arm of chromosome 2. This study shows that large-insert clones such as P1 are useful as chromosome-specific FISH probes and for gene mapping in oysters.

Chromosomal mapping of major ribosomal rRNA genes in the hard clam (Mercenaria mercenaria) using fluorescence in situ hybridization

Karyotype and chromosomal location of the major ribosomal RNA genes were studied in the hard clam (Mercenaria mercenaria Linnaeus) using fluorescence in situ hybridization (FISH). Metaphase chromosomes were obtained from early embryos. Internal transcribed spacers (ITS) between major RNA genes were amplified and used as FISH probes. The probes were labeled with digoxigenin-11-dUTP by polymerase chain reaction and detected with fluorescein-labeled anti-digoxigenin antibodies. FISH with the ITS probes produced two to four signals per nucleus or metaphase. M. mercenaria had a haploid number of 19 chromosomes with a karyotype of seven metacentric, four metacentric or submetacentric, seven submetacentric, and one submetacentric or subtelocentric chromosomes (7M + 4M/SM + 7SM + 1SM/ST). Two ITS loci were observed: one located near the centromere on the long arm of Chromosome 10 and the other at the telomere of the short arm of Chromosome 12. FISH signals on Chromosome 10 are strong and consistent, while signals on Chromosome 12 are variable. This study provides the first karyotype and chromosomal assignment of the major RNA genes in M. mercenaria. Similar studies in a wide range of species are needed to understand the role of chromosomal changes in bivalve evolution.

Chromosomal mapping of the major ribosomal RNA genes in the dwarf surfclam (Mulinia lateralis Say)

Chromosomal location of the major ribosomal RNA genes (rRNA) were studied in the dwarf surfclam (Mulinia lateralis, Say) using fluorescence in situ hybridization (FISH). FISH probes for the rRNA genes were made by polymerase chain reaction (PCR), labeled with digoxigenin-11-dUTP and detected with fluorescein-labeled antidigoxigenin antibodies. Mulinia lateralis had a diploid number of 38 chromosomes and all chromosomes were telocentric. FISH with the rRNA probe produced positive and consistent signals on two pairs of chromosomes: Chromosome 15 with a relative length of 4.6% and Chromosome 19, the shortest chromosome. Both loci were telomeric. The rRNA location provides the first physical landmark of the M. lateralis genome.

碳纳米管探针的制作方法研究

碳纳米管的小直径、高纵横比、高强度和高弹性、优良的耐磨损性能以及独特的电学和化学特性,使其成为高分辨率原子力显微镜的理想探针针尖。本文根据制作工艺的特点,综述现有碳纳米管探针的代表性研究和制作方法:组装式和生长式。组装式是通过手工、电场或磁场的方式将制备好的碳纳米管粘附到常规硅探针的末端;而生长式是在常规硅探针末端或悬臂梁上定点催化生长出一定直径和长度的CNT。最后指出这些方法目前存在的主要问题。

浅谈网络电子期刊的利用

介绍了网络电子期刊的定义和特点,论述了网络电子期刊的获取途径,探讨了网络电子期刊对图书馆等信息服务机构的影响。

波动方程模拟与偏移的实用化方法研究

Along with the widespread and in-depth applications in petroleum prospecting and development, the seismic modeling and migration technologies are proposed with a higher requirement by oil industrial, and the related practical demand is getting more and more urgent. Based on theories of modeling and migration methods for wave equation, both related with velocity model, I thoroughly research and develop some methods for the goal of highly effective and practical in this dissertation. In the first part, this dissertation probes into the layout designing by wave equations modeling, focusing on the target-oriented layout designing method guided by wave equation modeling in complicated structure areas. It is implemented by using the fourth order staggered grid finite difference (FD) method in velocity-stress 2D acoustic wave equations plus perfectly matched layer (PML) absorbing boundary condition. To design target-oriented layout: (a) match the synthetic record on the surface with events of subsurface structures by analyzing the snapshots of theoretical model; (b) determine the shot-gather distance by tracking the events of target areas and measuring the receiving range when it reaches the surface; (c) restrict the range of valid shot-gather distance by drawing seismic windows in single shot records; (d) choose the best trace distance by comparing the resolution of prospecting targets from the simulated records with different trace distance. Eventually, we obtained the observation system parameters, which achieve the design requirements. In the second part, this dissertation presents the practical method to improve the 3D Fourier Finite Difference (FFD) migration, and carefully analyzes all the factors which influence 3D FFD migration’s efficiency. In which, one of the most important parameters of migration is the extrapolating step. This dissertation presents an efficient 3D FFD migration algorithm, which use FFD propagator to extrapolate wavefields over big layers, and use Born-Kirchhoff interpolator to image wavefields over small layers between the big ones. Finally, I show the effectiveness of this hybrid migration method by comparing migration results from 3D SEG/EAGE model with different methods.

填土边坡水文作用机理与破坏过程研究—以深圳羊宝地填土滑坡为例

A full understanding of failure mechanism, critical hydrological condition, and process of mobilization and deposition of a landslide is essential for optimal design of stabilization measure and forecasting of landslide hazard. This requires a quantitative study of hydrological response of a slope to rainfall through field monitoring, laboratory test and numerical modelling. At 13:40 on September 18, 2002, a fill slope failed following a period of prolonged rain in Shenzhen, resulting in 5 fatalities and 31 injuries. The failed mass with a volume about 2.5×104m3 traveled about 140m on level ground. Field monitoring, laboratory test, theoretical analysis and numerical modelling were carried out to undestand the hydrological response and failure mechanism of this fill slope. This thesis mainly focuses on the following aspects: (1) The hydrological responses and failure processes of slopes under rainfall infiltration were reviewed. Firstly, the factors influencing on the hydrological responses of slopes were analysed. Secondly, the change of stress state of slope soil and modelling methods of slope failure under rainfall infiltration were reviewed. (2) The characteristics of the Yangbaodi landslide and associated rainfall triggering the failure were presented. The failure was characterized by shallow flowslide, due to an increase of ground water table caused by rainfall infiltration. (3) A fully automated instrumentation was carried out to monitor rainfall, and saturated – unsaturated hydrological response of the fill slope, using a raingauge, piezometers, tensiometers and moisture probes. A conceptual hydrogeological model was presented based on field monitoring and borehole data. Analysis of monitoring data showed that the high pore water pressure in fill slope was caused by upward flow of semiconfined groundwater in the moderately decomposed granite. (4) Laboratory and in-situ testing was performed to study the physical and mechanical properties of fills. Isotropically consolidated undrained compression tests and anisotropically consolidated constant shear stress tests were carried out to understand the failure mechanism of the fill slope. It is indicated that loosely compacted soil is of strain-softening behaviour under undrained conditions, accompanied with a rapid increase in excess pore water pressure. In anisotropically consolidated constant shear stress tests, a very small axial strain was required to induce the failure and the excess pore water pressure increased quickly at failure. This indicated that static liquefaction caused by rise in groundwater table due to rainfall infiltration occurred. (5) The hydraulic conductivity of the highly and moderately decomposed granite was estimated using monitering data of pore water pressure. A saturated – unsaturated flow was modeled to study the hydrological response of the fill slope using rainfall records. It was observed that the lagged failure was due to the geological conditions and the discrepancy of hydraulic conductivity of slope soils. The hydraulic conductivity of moderately decomposed granite is relatively higher than the other materials, resulting in a semiconfied groundwater flow in the moderately decomposed granite, and subsequent upward flow into the upper fill layer. When the ground water table in the fill layer was increased to the critical state, the fill slope failed. (6) Numerical exercises were conducted to replay the failure process of the fill slope, based on field monitoring, laboratory and in-situ testing. It was found that the fill slope was mobilized by a rapid transfer of the concentrated shear stress. The movement of failure mass was characterized by viscosity fluid with a gradual increase in velocity. The failure process, including mobilization and subsequent movement and deposition, was studied using numerical methods.

湛江湖光岩玛珥湖55ka以来植硅体化石记录及古环境变迁

The study of biogenic proxy of tropical and subtropical regions provides important evidence about the process and history of vegetation and environmental changes, and is of globally importance for understanding the dynamic mechanism of paleoclimatic and paleoenvironmental changes. The sediments from the Huguangyan Maar lake in Guangdong Province offer a continuous high-resolution record of the past 55 ka about environmental and vegetational changes. The studies of chronology, and physical, chemical environmental proxies have provided much important information about the paleoenvironmental and paleoclimatic histories. The phytolith, a new biogenicl proxy, has been used to determine the nature and types of plants in this area since the last 55 ka. This study presents a preliminary result about the characteristics of phytolith shapes, the variations of the fossils assemblages, and their significance for environmental changes. Moreover, the author probes the process of special specie evolution and their relationship to climatic parameters. The history of fire has been reconstructed based on the variations in charcoals. The main results and conclusions include: 28 types of phytoliths from 233 samples have been identified. Their environmental meanings are investigated in detail. Based on the variations in phytolith associations, the history and process of climatic and environmental changes in the last 55 kaBP have been established for this region. Climatic changes experienced eight intervals during this period, showing the variations of hot-humid to cool-try climate in the ten thousands years scale, and a shorter dry-hot climate condition in millennial scale. The history of palm plant has been established in this region. Two peaks appeared from 55-39 ka and since the Holocene. Plants in Bambusoideae have been growing in this area all the period, representing the impact of the East Asian summer monsoon. Bamboo plants have similar tendency in their abundance to palm plants, but with a lag of 1-2 ka BP. Panicoideae plants, the representative of C4 plants, have 6 flourishing periods occurred at 54.5, 44, 41.5, 32.5, 14, and 10 kaBP, respectively, reflecting 6 times short-term arid events. Charcoal record from the Huguang Marr lake reveals the history of nature fire, that mostly happened in dry period of last glacial from 55-10 kaBP, centered at 50-45, 40-35, 30-25, and 20-15kaBP, showing about a cycle of 10,000 years.

大港千米桥地区综合地质地球物理研究

Qianmiqiao buried hill, which is a high-yield burial hill pool, was discovered at Dagang oilfield in 1998. To employ the integrated geological and geophysical research at Qianmiqiao area, it is very valuable and meaningful for the petroleum exploration of Bohai Bay Basin and even the whole country. Based on the previous results, this paper is carried out from the research on Huanghua depression, following the law, i.e. the deep part constrains the shallow, the regional constrains the local, takes the geophysical research in Qianmiqiao oilfield, discusses the formation history of burial hills, burial history, thermal history, the generated and expelling history of hydrocarbon, and migration characteristics, probes into the formation of burial hill pool. This paper uses the gravity and magnetic methods which are based on potential field, with natural sources, configures the inner structure of the earth according to the difference in the density and magnetism of the rock. The geophysical characteristics of Dagang oil field is that it is an area with positive Buge gravity anomal. The upheaval of Moho boundary is in mirror symmetry with the depression of the basin's basement. The positive and negative anomaly distributein axis symmetry, and the orientation is NNE. The thickness of the crust gradually reduces from west to east, from land to sea. The depth gradient strip of Curie surface is similar to Moho boundary, whereas their local buried depth is different. Local fractures imply that the orientation of base rock fractures is NNE-NE, and the base rock is intersected by the fractures of the same/ later term, whose orientation is NW, so the base rock likes rhombic mosaic. The results of tomography show that there exists significant asymmetry in vertical and horizontal direction in the velocity configuration of Huanghua depression. From Dezhou to Tianjin, there exits high-speed block, which extends from south to north. The bottom of this high-speed block is in good agreement with the depth of Moho boundary. Hence we can conclude that the high-speed block is actually the crystal basement. According to seismic data, well data and outcrop data, Huanghua depression can be divided into four structure layers, i.e. Pi,2-T, Ji,2-K, E, N-Q. Qianmiqiao burial hills undergo many tectonic movement, where reverse faults in developed in inner burial hill from Indosinian stage to Yanshanian stage, the normal faults extended in Himalayan stage. Under the influence of tectonic movements, the burial hills show three layers, i.e. the reverse rushing faults in buried hills, paleo-residual hill, and extended horst block. The evolution of burial hills can be divided into four stages: steady raising period from Calenonian to early Hercynian, rushing brake drape period from Indosinian to middle Yanshanian, block tilting period in early Tertiary, and heating depression period from late Tertiary to Quaternary. The basin modeling softwares BasinMod 1-D and Basin 2-D, which are made by PRA corporation, are used in this paper, according to the requirement, corresponding geological model is designed. And we model the burial history, thermal history, hydrocarbon generation and hydrocarbon expelling history of Qianmiqiao area. The results show that present bury depth is the deepest in the geological history, the sedimentary rate of Tertiary is highest and its rising rate of temperature rate is higher. During sedimentary history, there is no large erosion, and in the Tertiary, the deeper sediment was deposited in large space, therefore it is in favor of the conservation and transformation of oil and gas. The thermal research shows that the heat primarily comes from basement of the basin, present geotherm is the highest temperature in the geological history. Major source rock is the strata of ES3, whose organic is abundant, good-typed, maturative and of high-expulsive efficiency. The organic evolution of source rock of O has come to the overmature stage, the evolving time is long and the source rock can be easily destroyed. Therefore it is more difficult for the O formation source rock to form the huge accumulation of oil and gas than Es3 formation. In the research of oil assembling, we first calculated the characteristics of the fluid pressure of single well, then analyzed the distribution of the surplus fluid pressure of each formation and profile, and probe the first hydrocarbon migration situation and the distribution of pressure system of buried hill pool. In every formation, the pressure system of each burial hill has its own characteristics, e.g. high pressure or low pressure. In the research of secondary migration, the fluid potential is calculated while the relative low potential area is figured out. In Qianmiqiao area, the west margin faults have the low potential, and hence is the favorable reconnoiter belt.

黄东海及朝鲜海峡冰后期陆架沉积物的环境磁学研究

There are four chapters in this dissertation. The first chapter briefly synthesizes the basic theories, methods and present-day applying situation of environmental magnetism. The second chapter probes into the magnetic mineral diagenesis in the post-glacial muddy sediments from the southeastern South Yellow Sea and its response to marine environmental changes, using the muddy sediment of Core YSDP103 formed in the shelf since about 13 ka BP. The third chapter illustrates the high-resolution early diagenetic processes by investigating the rapidly deposited muddy sediments during the last 6 ka in Cores SSDP-102 and SSDP-103 from the near-shore shelf of Korea Strait. The fourth chapter presents the results of detailed rock magnetic investigation of the surface sediments from the fine-grained depositional area on the outer shelf of the East China Sea in an attempt to provide environmental magnetic evidence for the provenance of the fine-grained deposit. Core YSDP103 was retrieved in the muddy deposit under the cold eddy of the southeastern South Yellow Sea, and the uppermost 29.79 m core represents the muddy sediments formed in the shelf since about 13 ka BP. The lower part from 29.79 to 13.35 m, called Unit A2, was deposited during the period from the post-glacial transgression to the middle Holocene (at about 6 ~(14)C ka BP) when the rising sea level reached its maximum, while the upper part above 13.35 m (called Unit Al) was deposited in a cold eddy associated with the formation of the Yellow Sea Warm Current just after the peak of post-glacial sea level rise. For the the uppermost 29.79 m core, detailed investigation of rock-magnetic properties and analyses of grain sizes and geochemistry were made. The experimental results indicate that the magnetic mineralogy of the core is dominated by magnetite, maghemite and hematite and that, except for the uppermost 2.35 m, the magnetic minerals were subject to reductive diagenesis leading to significant decline of magnetic mineral content and the proportion of low-coercivity component. More importantly, ferrimagnetic iron sulphide (greigite) is found in Unit A2 but absent in Unit Al, suggesting the control of marine environmental conditions on the magnetic mineral diagenesis. Magnetic parameters show abrupt changes across the boundary between the Unit Al and A2, which reflects a co-effect of environmental conditions and primary magnetic components of the sediments on the diagenesis. Alternating zones of high and low magnetic parameters are observed in Unit A2 of Core YSDP103, which is presumably due to periodic changes of the concentration and/or grain size of magnetic minerals carried into the study area. Cores SSDP-102 and SSDP-103, two studied sediment cores from the Korea Strait contain mud sequences (14 m and 32.62 m in thickness) that were deposited during the last 6,000 years. Analyses of grain sizes and geochemistry of the cores have demonstrated that the sediments have uniform lithology and geochemical properties, however, marked down-core changes in magnetic properties suggest that diagenesis has significantly impacted the magnetic properties. An expanded view of early diagenetic reactions that affect magnetic mineral assemblages is evident in these rapidly deposited continental shelf sediments compared to deep-sea sediments. The studied sediments can be divided into four descending intervals, based on magnetic property variations. Interval 1 is least affected by diagenesis and has the highest concentrations of detrital magnetite and hematite, and the lowest solid-phase sulfur contents. Interval 2 is characterized by the presence of paramagnetic pyrite and sharply decreasing magnetite and hematite concentrations, which suggest active reductive dissolution of detrital magnetic minerals, the absolute minimum abundance of magnetite is reached at the end of this interval. Interval 3 is marked by a progressive loss of hematite with depth, and at the base of this interval, 82% to 88% of the hematite component was depleted and the bulk magnetic mineral concentration was reduced to the lowest value in the entire studied mud section. Interval 4 has an increasing down-core enhancement of authigenic greigite, which is interpreted to have formed due to arrested pyritization resulting from consumption of pore water sulfate with depth. This is the first clear demonstration from an active depositional environment for a delay of thousands of years for acquisition of a magnetization carried by greigite. This detailed view of diagenetic processes in continental shelf sediments suggests that studies of geomagnetic field behavior from such sediments should be conducted with care. Paleoceanographic and paleoclimatic studies based on the magnetic properties of shelf sediments with high sedimentation rates like those in the Korea Strait are also unlikely to provide a meaningful signature associated with syn-depositional environmental processes. The rock magnetic properties of the surface sediments from the fine-grained depositional area on the outer shelf of the East China Sea, an area surrounded by sands, are investigated with a view to providing information on the sediment provenance. Multiple magnetic parameters such as magnetic susceptibility (%), anhysteretic remanent magnetization (ARM), saturation rernanent magnetization (SIRM), coercivities of SIRM (Her), and S ratios (relative abundance of low-coercivity magnetic minerals) are measured for all 179 surface samples, and partial representative samples are examined for their magnetic hysteresis parameters, temperature-dependence of magnetic susceptibility and x-ray diffraction spectra. Our research indicates that the magnetic mineralogy is dominated by magnetite with a small amount of hematite and is primarily of pseudo-single domain (PSD) to multidomain (MD) nature with a detrital origin. In the surface sediments, the granulometry of magnetic fractions is basically independent of grain sizes of the sediment containing the magnetic grains, and the composition of magnetic minerals remains almost homogeneous, that is, with a relatively constant ratio of low to high coercivity fraction throughout the area. The magnetic concentration in the study area generally decreases to the east or southeast accompanied by magnetic-particle fining to the east or to the northeast. The geographic pattern of magnetic properties is most reasonably explained by a major source of sediment jointly from the erosion of the old Huanghe River deposit and the discharge of the Changjiang River. The rock magnetic data facilitate understanding of the transport mechanism of fine-grained sediments in the outer shelf of the East China Sea.

A homogeneous DNA hybridization system by using a new luminescence terbium chelate

Homogeneous DNA hybridization assay based on the luminescence resonance energy transfer (LRET) from a new luminescence terbium chelate, N,N,N-1,N-1-[2,6-bis(3'-aminomethyl-1'-pyrazolyl)-4-phenylpyridine]tetrakis(acetic acid) (BPTA)-Tb3+ (lambda(ex) = 325 nm and lambda(em) = 545 nm) to an organic dye, Cy3 (A,. = 548 nm and A,. = 565 nm), has been developed. In the system, two DNA probes whose sequences are complementary to the two different consecutive sequences of a target DNA are used; one of the probes is labeled with the Tb3+ chelate at the T-end, and the other is with Cy3 at the 5'-end. Labeling of the Tb3+ chelate is accomplished via the linkage of a biotin-labeled DNA probe with the Tb3+ chelate-labeled streptavidin. Strong sensitized emission of Cy3 was observed upon excitation of the Tb3+ chelate at 325 run, when the two probe DNAs were hybridized with the target DNA. The sensitivity of the assay was very high compared with those of the previous homogeneous-format assays using the conventional organic dyes; the detection limit of the present assay is about 30 pM of the target DNA strand.