Characterization of the structural and functional changes of hemoglobin in dimethyl sulfoxide by spectroscopic techniques

Circular dichroism (CD), fourier transform infrared (FTIR), and fluorescence spectroscopy were used to explore the effect of dimethyl sulfoxide (DMSO) on the structure and function of hemoglobin (Hb). The native tertiary structure was disrupted completely when the concentration of DMSO reached 50% (v/v), which was determined by loss of the characteristic Soret CD spectrum. Loss of the native tertiary structure could be mainly caused by breaking the hydrogen bonds, between the heme propionate groups and nearby surface amino acid residues, and by disorganizing the hydrophobic interior of this protein. Upon exposure of Hb to 52% DMSO for ca. 12 h in a D2O medium no significant change in 1652 cm(-1) band of the FTIR spectrum was produced, which demonstrated that alpha-helical structure predominated. When the concentration of DMSO increased to 57%: (1) the band at 1652 cm(-1) disappeared with the appearance of two new bands located at 1661 and 1648 cm(-1); (2) another new band at 1623 cm(-1) was attributed to the formation of intermolecular beta-sheet or aggregation, which was the direct consequence of breaking of the polypeptide chain by the competition of S=O groups in DMSO with C=O groups in amide bonds. Further increasing the DMSO concentration to 80%, the intensity at 1623 cm(-1) increased, and the bands at 1684, 1661 and 1648 cm(-1) shifted to 1688, 1664 and 1644 cm(-1), respectively. These changes showed that the native secondary structure of Hb was last and led to further aggregation and increase of the content of 'free' amide C=O groups. In pure DMSO solvent, the major band at 1664 cm(-1) indicated that almost all of both the intermolecular beta-sheet and any residual secondary structure were completely disrupted. The red shift of the fluorescence emission maxima showed that the tryptophan residues were exposed to a greater hydrophilic environment as the DMSO content increased. GO-binding experiment suggested that the biological function of Hb was disrupted seriously even if the content of DMSO was 20%. (C) 1998 Elsevier Science B.V. All rights reserved.

Recent development of intermediate ion/neutral complexes

The fundamental aspects of ion/neutral complex as an important intermediate of unimolecular fragmentation in mass spectrometry have been summarized in this review, especially for the classified description of its formations, characteristics, reactions, investigation methods, recent achievements and application. Meanwhile, another kind of proton-bound complex, which is a special type of ion/neutral complex, has been also introduced briefly. Among them, a part of authors' work was included.

离子/中性复合物中间体研究进展

对离子／中性（碎片）复合物的形成、特征、反应、研究方法和近年来取得的重要成就及其应用进展进行了综述．简述了另一类特殊形式的离子／中性（碎片）复合物质子键合复合物.

稀土3,4-呋喃二甲酸,1,10-二氮杂菲配合物的光物理性质

研究了稀土Ｇｄ３＋、Ｅｕ３＋、Ｔｂ３＋的３，４呋喃二甲酸，１，１０二氮杂菲（Ｐｈｅｎ）配合物的合成、红外光谱、紫外光谱及光物理性质。详细讨论了配合物的分子内能量传递过程。发现分子内能量传递效率依赖于稀土中心离子的共振发射能级与配体最低三重态能级之间的相对位置。

[(t-BuCp)_2PrCl]_2的合成和晶体结构

叔丁基环戊二烯钠和无水三氯化镨在四氢味喃中反应,产物经过甲苯处理,分离得到配合物[(t-BuCp)_2PrCl]_2对该配合物进行了元素分析,红外光谱和~1HNMR表征。同时测得了它的单晶结构。该配体属正交晶系,C_(mca)空间群,晶胞参数为:a=2.378(6)nm,b=0.9565(1)nm,c=1.6455(4)nm,V=3.743nm~3,Z=4。R=0.042。Pr—Cl键长为0.2864nm。Pr-Cent(环中心)为0.2489nm。Pr-Pr(a)为0.4041nm。

聚丙烯/高密度聚乙烯高取向共混物的附生结晶

最近,聚合物之间的附生结晶引起人们的极大兴趣和关注。附生结晶是一种结晶物质在另一种结晶物质上的取向生长,二者之间有特殊的作用。这种附生作用对结晶聚合物共混体系的形态结构和性能有极为重要的影响。本工作以电子显微镜方法研究熔体拉伸直接导致等规聚丙烯(iPP)和高密度聚乙烯(HDPE)共混物附生结晶。

Bi系高温超导体中2212相和2223相的性质分析

本文对 Bi 系中可能存在一种 T_c>100K 的2212相作了进一步的论证.化学分析显示普通的2212相中 Cu~(3+)含量为～10%,而2223相和 T_c>100K 的2212相中 Cu~(3+)的含量却大于30%.从 DTA-TG 实验中观察到普通2212相和2223相失去晶格氧的量为0.8%,而含 T_c>100K 的2212相的样品失去晶格氧的量为～2%,说明这种2212相受氧含量影响更大.文中还介绍了一种简易判断样品中是否存在2223相和普通2212相的经验方法.

固体中Eu~(3+)离子能级的晶场效应

本文分析了晶场对稀土离子的影响,考虑了J混效应引起的能级位移,具体计算了20个含Eu~(3+)离子的晶体中Eu~(3+)离子的slater参数,并给出了随着基质不同的变化规律。

Sex-linked microsatellite marker detected in the female gametophytes of Undaria pinnatifida (Phaeophyta)

P>In our microsatellite analysis of three male and three female gametophytes of Undaria pinnatifida (Harv.) Suringar, a microsatellite marker (part of the locus Up-AC-2A8, GenBank accession no. AY738602.1) was only polymerase chain reaction-amplified in three female gametophytes. This putative female-specific marker was further tested by the use of 32 male and 21 female gametophytes maintained in the Marine Biological Culture Collection Centre, China. In addition, three sporophytes were included for confirmation. Results showed that the marker was present in all of the female gametophytes and sporophyte cultures, but absent in all of the male gametophytes. To our knowledge, this is the first sex-related marker ever reported in U. pinnatifida. The discovery of this marker will accelerate gender identification and shed light on our understanding of the mechanisms of sex determination at a molecular level in this commercially important seaweed.

Structural analysis of SNARE motifs from sea perch, Lateolabrax japonicus by computerized approaches

Three cDNA sequences encoding four SNARE (N-ethylmaleimide-sensitive fusion protein attachment protein receptors) motifs were cloned from sea perch, and the deduced peptide sequences were analyzed for structural prediction by using 14 different web servers and softwares. The "ionic layer" structure, the three dimensional extension and conformational characters of the SNARE 7S core complex by using bioinformatics approaches were compared respectively with those from mammalian X-ray crystallographic investigations. The result suggested that the formation and stabilization of fish SNARE core complex might be driven by hydrophobic association, hydrogen bond among R group of core amino acids and electrostatic attraction at molecular level. This revealed that the SNARE proteins interaction of the fish may share the same molecular mechanism with that of mammal, indicating the universality and solidity of SNARE core complex theory. This work is also an attempt to get the protein 3D structural information which appears to be similar to that obtained through X-ray crystallography, only by using computerized approaches. (C) 2007 Elsevier Ltd. All rights reserved.

Response of coastal marine eco-environment to river fluxes into the sea: A case study of the Huanghe (Yellow) River mouth and adjacent waters

The impact of the Huanghe (Yellow) River outflows on its estuary was investigated with river gauging and shipboard hydrographic observations. The river flux has been decreasing dramatically; the discharges of water and sediment in the 1990s dropped to 27.4% and 31.9% of those in the 1950s, respectively, resulting in frequent and lengthy events of downstream channel dry-up since the 1970s. There were accumulatively 897 zero-flow days during the 1990s in the river course below the Lijin Hydrological Station, 100 km upstream from the river mouth, which is 82.4% of that in 1972. As freshwater input decreases, river-borne nutrients to the estuarine increased significantly. Concentration of dissolved inorganic nitrogen (DIN) in the 1990s was four times of that in 1950s. Changes in amount and content of the riverine inputs have greatly affected the estuarine ecosystem. Over the past several decades, sea surface temperature and salinity in the estuary and its adjacent waters increased and their distribution pattern altered in response to the reduction of freshwater inflow. The distribution of and seasonal succession in nutrient concentrations in the surface layer have also changed with a shift of river outlet and the decrease in riverine nutrient loads. Furthermore, deterioration of estuarine ecosystem by less river input has decreased primary productivity in the deltaic region waters, and in turn depressed the fishery. (C) 2008 Published by Elsevier Ltd.

Paleoenvironmental change in the middle Okinawa Trough since the last deglaciation: Evidence from the sedimentation rate and planktonic foraminiferal record

Well-dated, high-resolution records of planktonic foraminifera and oxygen isotopes from two sediment cores, A7 and E017, in the middle Okinawa Trough reveal strong and rapid millennial-scale climate changes since similar to 18 to 17 thousand years before present (kyr B.P.). Sedimentation rate shows a sudden drop at similar to 11.2 cal. kyr B.P. due to a rapid rise of sea level after the Younger Dryas (YD) and consequently submergence of the large continental shelf on the East China Sea (ECS) and the retreat of the estuary providing sediment to the basin. During the last deglaciation, the relative abundance of warm and cold species of planktonic foraminifera fluctuates strongly, consistent with the timing of sea surface temperature (SST) variations determined from Mg/Ca measurements of planktonic foraminifera from one of the two cores. These fluctuations are coeval with climate variation recorded in the Greenland ice cores and North Atlantic sediments, namely Heinrich event 1 (H1), Bolling-Allerod (B/A) and YD events. At about 9.4 kyr B.P., a sudden change in the relative abundance of shallow to deep planktonic species probably indicates a sudden strengthening of the Kuroshio Current in the Okinawa Trough, which was synchronous with a rapid sea-level rise at 9.5-9.2 kyr B.P. in the ECS, Yellow Sea (YS) and South China Sea (SCS). The abundance of planktonic foraminiferal species, together with Mg/Ca based SST, exhibits millennial-scale oscillations during the Holocene, with 7 cold events (at about 1.7, 2.3-4.6, 6.2, 7.3, 8.2, 9.6, 10.6 cal. kyr BP) superimposed on a Holocene warming trend. This Holocene trend, together with centennial-scale SST variations superimposed on the last deglacial trend, suggests that both high and low latitude influences affected the climatology of the Okinawa Trough. (c) 2006 Elsevier B.V. All rights reserved.

海洋环流的若干数值模式研究

本文可分为较为独立的三部分，旨在研制从大洋到陆架浅海的若干海洋环流的数值模式。第一部分是大洋环流的一个全流－表层流数值模式。它是“七五”期间国家重点攻关项目76－01－02专题（海流数值预报）的部分研究工作。基于目前所能收集到的最齐全的历史资料，而建立起来的全流－表层流数值模式给出了与实测良好符合的西北太平洋季度平均表层流结果。综合海流业务预报模式的建立则是国内开创性工作，在国际上亦不多见。在没有先例可循的条件下，我们摸索了一整套解决的办法，并取得了预期的效果。第二部分是针对陆架和浅海环流特点而建立起来的一个三维海流数值模式。该模式的建立，解决了三维海流数值计算过程中必然遇到的垂直方向分层不便，浅水区垂向分辨率低等问题；将实际海域转化为平底问题处理，大大简化了程序设计的过程；由混合长度理论来确定垂直涡动粘性系数，既避免了以往对该系数取值的任意性，又能在计算量不太大的前提下给出准确、合理的数值。从而，在很大程度上改进了以往传统的海洋环流三维数值模式。第三部分则是应实际工作需要，在第二部分的基础上建立起来的一个二维和三维嵌套的水动力学数值模型。该模型的建立，可以视为第二部分所述模式在实际应用方面的继续改进。该模型的研制旨在满足三维数值计算要求的前提下，最大限度地节省计算时间，成倍地提高工作效率。

青海湖地区芨芨草群落主要种群分布格局研究

以青海省三角城种羊场地区典型的芨芨草草原为研究对象，采用相邻格子样方法取样，应用方差／均值比率法、负二项参数（K）；扩散系数（C）；Cassie指标（CA）；丛生指标（I）和聚块性指标（m^＊／m）等指标，比较了青海湖地区围栏内、外芨芨草群落主要种群的空间分布格局。结果表明，围栏内芨芨草群落优势种群的空间格局除多裂蒲公英为随机分布外，其余均为聚集分布；围栏外除西伯利亚蓼外，其余种群也全部为聚集分布，而且围栏外种群的聚集强度大于围栏内。物种的这种分布格局主要与物种本身的生态和生物学特性有关。

鹅观草属部分种的叶表皮微形态特征及其分类学意义

在过去叶表皮实验的基础上,本文从鹅观草属不同组、系中新增解剖了16 个有代表性的种。根据这些种叶片反映的表皮微形态特征,进一步证实了鹅观草属共族分属以及属下类群划分的正确性,揭示了属中各主要类群的演化水平和系统发育关系。研究结果最后表明:鹅观草属的半颖组最原始,在系统发育中它可能既派生了较进化的小颖组和大颖组,又派生了最进化的长颖组;在大颖组中,齿草系较原始,纤毛草系较进化,宽叶草系最进化,纤毛草系和宽叶草系可能相继起生于齿草系。并且,鹅观草属的这种进化关系同过去细胞学和形态学提供的证据是基本一致的。