野生与豢养长江江豚血清氨基酸含量比较

应用高效液相色谱(HPLC)技术,首次测定了湖北石首长江天鹅州白豚自然保护区野生长江江豚(Neopho-caena phocaenoides asiaeorientalis)和中国科学院水生生物研究所白豚馆人工饲养的长江江豚血清中17种氨基酸的含量。结果表明,除了脯氨酸Pro、蛋氨酸Met和组氨酸His外,人工饲养江豚血清中其余14种氨基酸(天门冬氨酸Asp、谷氨酸Glu、丝氨酸Ser、精氨酸Arg、甘氨酸Gly、苏氨酸Thr、丙氨酸Ala、异亮氨酸Ile、亮氨酸Leu、苯丙氨酸Phe、缬氨酸Val、赖氨

微囊藻毒素[Dha~7]MCRR的制备及鉴定

以野外收集的水华蓝藻为原料,经过75%甲醇溶液浸提,快速色谱分离和半制备色谱纯化,从滇池水华蓝藻中分离纯化出1种微囊藻毒素变体.电喷雾质谱、紫外分光光度计和HPLC检测结果表明,所得毒素为[Dha7]MCRR,是MCRR的1种去甲基化变体,其纯度大于95%.该毒素的分子组成为环(Ala-Arg-MeAsp-Arg-Adda-Glu-Dha),分子量为1 023,其紫外扫描光谱(200~300 nm)在239 nm处有特征吸收.[Dha7]MCRR在滇池水华蓝藻中普遍存在,有时会成为MC的主要种类.

微囊藻毒素RR的制备及鉴定

以野外收集的水华蓝藻为原料,建立了以75%甲醇溶液提取、快速色谱和半制备色谱分离为主要步骤的微囊藻毒素分离纯化方法,并用HPLC、分光光度计和电喷雾质谱对所得毒素的纯度和结构进行了鉴定.结果表明,所得毒素为MCRR,纯度大于95%,其紫外吸收光谱在239nm处有特征吸收,分子组成为环(Ala-Arg-MeAsp-Arg-Adda-Glu-Mdha),分子量为1037.

铜绿微囊藻毒株M.8641的毒素

M.8641是从武汉东湖分离培养的一株有毒的铜绿微囊藻(Microcystis aeruginosa),它产生两种环状短肽肝毒素。经凝胶过滤及HPLC等过程纯化,Waters Pico Tag系统测定,其主毒素(毒素Ⅰ)的氨基酸组成为:Glu(1),β-Masp(1),Ala(Ⅰ),Arg(2),Mdha(1),FAB-MS和MS/MS测定分子量为m/z1038,元素组成为C_(49)H_(76)O_(12)N_(13)。毒素Ⅱ的氨基酸组成,除一分子Arg为Leu取代外,其余与毒素Ⅰ相同,分子量m/z 9

用鱼血δ-氨基乙酰丙酸脱水酶指示水体中铅污染的研究

水中不同铅浓度(5—500μg/l)急性致毒使白鲢血液中δ-氨基乙酞丙酸脱水酶(ALA-D)活性随铅浓度的增加而呈线性关系下降.温度越高,铅对酶活性的抑制越明显。0.1ppm汞、镉、铜,0.008ppm滴滴涕和0.84ppm对硫磷急性致毒,除对硫磷外对草鱼血ALA-D活性皆没有显著性影响.锌、镉、铜分别与铅混合,降低铅对ALA-D酶的抑制作用,致毒四天,可恢复甚至刺激鱼血ALA-D酶活性.被重金属(包括铅)污染的S湖中白鲢血ALA-D酶表现出明显的抑制作用,但鲤鱼血ALA-D酶却测不出抑制作用

Temporal and Spatial Distributions of Rotifers in Xiangxi Bay of the Three Gorges Reservoir, China

From July 2003 to June 2005, investigations of rotifer temporal and spatial distributions were carried out in a bay of the Three Gorges Reservoir, Xiangxi Bay, which is the downstream segment of the Xiangxi River and the nearest bay to the Three Gorges Reservoir dam in Hubei Province, China. Thirteen sampling sites were selected. The results revealed a high species diversity, with 76 species, and 14 dominant species; i.e., Polyarthra vulgaris, Keratella cochlearis, Keratella valga, Synchaeta tremula, Synchaeta stylata, Trichocerca lophoessa, Trichocerca pusilla, Brachionus angularis, Brachionus calyciflorus, Brachionus forficula forficula, Ascomorpha ovalis, Conochilus unicornis, Ploesoma truncatum and Anuraeopsis fissa. After the first year of the reservoir impoundment, the rotifer community was dominated by ten species; one year later it was dominated by eight species. The community in 2003/2004 was dissimilar to that in 2004/2005, which resulted from the succession of the dominant species. The rotifer community exhibited a patchy distribution, with significant heterogeneity observed along the longitudinal axis. All rotifer communities could be divided into three groups, corresponding to the riverine, the transition and the lacustrine zone, respectively.

An Evaluation of Four Phylogenetic Markers in Nostoc: Implications for Cyanobacterial Phylogenetic Studies at the Intrageneric Level

The success of some phylogenetic markers in cyanobacteria owes to the design of cyanobacteria-specific primers, but a few studies have directly investigated the evolution "behavior" of the loci. In this study, we performed a case study in Nostoc to evaluate rpoC1, hetR, rbcLX, and 16S rRNA-tRNA(Ile)-tRNA(Ala)-23S rRNA internal transcribed spacer (ITS) as phylogenetic markers. The results indicated that the gene trees of these loci are not congruent with the phylogeny based on 16S rRNA gene. The mechanisms contributing to the incongruence include randomized variation and recombination. As the results suggested, one should be careful to choose the molecular markers for phylogenetic reconstruction at the intrageneric level in cyanobacteria.

Detection and quantitative analysis of polychlorinated biphenyls in tilapia from Hawaiian waters

The purpose of this study was to investigate polychlorinated biphenyls (PCBs) contamination in tilapia (Oreochromis mossambicus) collected from the Manna stream and Ala Wai Canal of O'ahu, an island of the geographically isolated Hawaiian archipelago. Our results show that the average concentrations of PCBs varied from 51.90 to 89.42 ng g(-1) lipid weight for the sampling sites. Relative toxic potencies (RTPs) and toxic equivalencies (TEQs) were determined to be 20.38-40.60 ng TCDD g(-1) lipid weight and 2.89-4.17 ng TEQ g(-1) lipid weight by 7-ethoxy-resorufin-O-deethylase (EROD) activity analysis and calculation of PCB concentrations based on toxic equivalency factors (TEFs), respectively. Penta-chlorinated congeners were found to be predominant, which revealed that Aroclor 1254 was a possible major source of PCBs in our fish samples. PCB 118, an indicator PCBs, constituted more than 55% and 30% of the total PCBs and TEQs, respectively. In addition, PCB 118 was found to have a linear correlation to the total PCBs (R = 0.975) and TEQs (R = 0.782). Detection of concentrated PCBs in Hawaiian waters suggests a potentially adverse impact of this pollutant on human health, as well as ecological systems, and suggests the necessity of environmental monitoring and hazard assessment of PCBs within the Hawaiian Islands. (c) 2008 Published by Elsevier Ltd.

Identification of novel SINEs from Cyprinidae and their evolutionary significance

Short interspersed nuclear elements (SINEs) are widespread among eukaryotic genomes. They are repetitive DNA sequences that have been amplified by retrotransposition. In this study, a class of SINEs were isolated from the Opsariichthys bidens genome, and named Opsar. Sequence analysis confirmed that Opsar is a new class of typical SINEs derived from tRNA molecules. With the tRNA-derived region of Opsar and through BLASTN search, we further identified Zb-SINEs from the zebrafish genome, which includes two groups: Zb-SINE-A and Zb-SINE-B. The Zb-SINE-A group comprises subfamilies of -Al--A5, and the Zb-SINE-B group is a dimer of the tRNA(Ala)-derived region and shares a similar dimeric composition to Alu. Zb-SINEs are composed of three distinct regions: a 5 end tRNA-derived region, a tRNA-unrelated region and a 3 end AT-rich region. The flanking regions are AT rich. The average length of Zb-SINEs elements is about 340 6p. Zb-SINEs account for as much as 0.1% of the whole zebrafish genome. About 70% of the Zb-SINEs are on chromosomes 11, 18, and 19. These Zb-SINEs were characterized by PCR and dot hybridization. The distribution pattern of Zb-SINEs in genome strongly supports the master genes model. The tRNA-derived regions of Opsar and Zb-SINEs were compared with the tRNA(Ala) gene, and they showed 76% similarity, indicating that Opsar and Zb-SINEs originated from an inactive tRNA(Ala) sequence or a tRNA(Ala)-like sequence. In view of the evolutionary status of zebrafish in the Cyprinidae, we deduced that Zb-SINEs were a very old class of interspersed sequences.

The impact of silver carp (Hypophthalmichthys molitrix) on the rotifer community in a eutrophic subtropical Chinese lake

From 20 April to 25 June in 1999, an enclosure experiment was conducted in Lake Donghu to assess the impact of planktivorous silver carp on the planktonic rotifer community. We set up four treatments with silver carp biomass at 0, 116, 176, and 316 g m(-2). Total rotifer density was significantly higher in the no-fish enclosure than in fish-present enclosures. Fish predation on the rotifers alleviated zooplankton competition and resulted in dominance of small zooplankton species (Anureaopsis fissa, Trichocerca pusilla and Moina micrura) in fish-present enclosures. However, some relatively larger species (Polyarthra vulgaris, Brachionus angularis, Brachionus calyciflorus, and Asplanchna spp.) showed higher densities in the no-fish enclosure than in fish-present enclosures.

Enhancement of planktonic rotifers by Microcystis aeruginosa blooms: An enclosure experiment in a shallow eutrophic lake

Enclosure experiments with three treatments (sediment addition, sediment + nitrogen enrichment, sediment + phosphorus enrichment) and unfertilized controls were performed in shallow hypereutrophic Lake Donghu during the summer of 2000. Dense Microcystis aeruginosa blooms occurred in all the enclosures during the experimental period but not in the surrounding lake water. Generally, the dominant rotifers were Polyarthra vulgalis, Filinia longiseta, Proales sp. and Asplanchna sp. at the beginning of the experiment, followed by a shift to Brachionus calyciflorus, Trichocerca similis, Cephalodella catellina and Anuraeopsis fissa, and finally to F. longiseta, Proales sp. and Keratella cochleris. M. aeruginosa blooms strongly suppressed the larger Diaphanosoma brachyurum but enhanced the development of the smaller cladocerans and rotifers that probably efficiently utilized organic matter from M. aeruginosa through the detritus food chain. The smaller cladoceran and rotifers coexisted successfully throughout the experimental period.

Long-term changes of planktonic rotifers in a subtropical Chinese lake dominated by filter-feeding fishes

1. The long-term changes (1956-1998) in density and species composition of planktonic rotifers were studied at two sampling stations (I, II) of Lake Donghu, a shallow eutrophic Chinese Lake densely stocked with filter-feeding fishes. Annual average densities of rotifers increased with an increase in fish yield and eutrophication, whilst species number decreased from 82 in 1962-1963 to 62 in 1994-1998. 2. During 1962-98, some species such as Anuraeopsis fissa, Polyarthra spp. (including P. dolichoptera & P. vulgaris), Trichocerca pusilla and Synchaeta oblonga increased their percentage in abundance remarkably, whilst the proportion of Keratella cochlearis decreased at two relatively eutrophic stations from 19 to 4.2% at Station I and from 30 to 3.2% at Station IL 3. The high r(max) of A. fissa probably made it more successful than other rotifers under high predation pressure by planktivorous fish. The decrease in the K. cochlearis population might be attributed partly to predation by Cyclops vicinus. 4. Small rotifers were less vulnerable to fish predation than large-sized cladocerans. Decreases in cladocerans coincided with increases in rotifers, suggesting that the indirect effect of fish predation on cladocerans might have partly contributed to the population development of rotifers in Lake Donghu during recent decades. 5. We also conducted surveys (1994-1998) of seasonal dynamics of rotifers at four sampling stations (I-IV) which have varied in trophic status after fragmentation of the lake in the 1960s. A total of 75 species were identified at the four stations. Both densities and biomass of rotifers were considerably higher in the two more eutrophic stations than in the two less eutrophic stations. This indicates that the population increase of rotifers at Stations I and II during recent decades might be partly attributed to eutrophication of the lake water.

5-氨基乙酰丙酸对日光温室番茄生长发育和产量品质的影响

为外源5-氨基乙酰丙酸(ALA)在日光温室蔬菜上的应用提供科学依据。【方法】研究了不同浓度ALA处理对日光温室番茄生产的影响。【结果】ALA以及ALA+N叶面施用均明显提高了番茄植株株高、叶绿素相对含量和果实产量,并改善了番茄果实品质;与对照相比,外源ALA各处理植株株高、叶绿素相对含量和单株生物产量均有明显提高,其中D处理(ALA1号肥料第1次2 kg/hm2,第2~4次1 kg/hm2)效果最佳,植株株高、叶绿素相对含量及单株生物产量分别提高27.18%,17.75%和13.93%;外源ALA对番茄果实产量和品质也有明显的提高和改善作用,其中处理B(ALA1号肥料第1次0.5 kg/hm2,第2~4次0.3 kg/hm2)对果实产量效果最明显,处理E(ALA3号肥料第1次2.5 kg/hm2,第2~4次1.5 kg/hm2)对果实品质效果最佳。【结论】处理E(ALA3号肥料第1次2.5 kg/hm2,第2~4次1.5 kg/hm2)既有利于番茄生长发育,又能增加产量并改善品质,为最佳的ALA施用量及方法。

铝及其形态的分析方法

我在研究生期间所做的论文为铝及其形态的分析方法。为什么要做这项工作呢？许多研究表明：①铝是天然水和土壤中十分重要的pH缓冲剂，②铝能影响土壤中象磷和有机碳这些重要元素的环比，③铝对动物、植物及人体都有害，这些过程都与铝的形成有关，因此弄清铝的形态及测定各种形态的浓度十分有意义。由于铝在水中含量较低，且水中含有其它共存离子，因此围绕铝形态的分析，首先建立了一种抗干扰，高灵敏的方法来测定总铝量及各种形态铝的浓度。利用铬天青s试剂测定铝的方法很多，铝与铬天青s能形成红色的二元配合物，但其灵敏度低，稳定性差。近年来人们大多采用铝－铬天青S－表面活性剂三元体系，提高了灵敏度和选择性。本文研究了铝－铬天青S－溴代＋元烷基吡啶三元显色体系，试验确定了三元显色体系的最佳显色条件。其条件如下：实验结果及选定的条件 影响因素 实验结果 选定条件 显色酸度 pH 5.5～7.5 6.0 1 * 10~(-4)M CAS溶剂用量 0.3～0.5ml 0.4ml 5 * ~(-3)M CPB的用量 0.5～1.5ml 0.9ml此三元体系十分稳定，在常温下，显色液放置40分钟才能基本发色完全，其吸光度在24小时内无变化。实验方法为于50ml容量瓶中，加入铝标准液，然后加0.4ml 1 * 10~(-4)M CAS溶液，0.9ml CPB 5 * 10~(-3)M溶液，加入用盐酸调好的pH≈6的六次甲基四胺缓冲液5ml，用水定容，放置40分钟，于644nm处，1cm比色池，以试剂空白作参电测定吸光度。当铝量为0～5ug/50ml时，有色配合物遵从电尔定律，其线性相关系数为0.9999，表观摩尔吸光系数ε_(644nm) = 1.43 * 10~5 l·mol~(-1)·cm~(-1)。本法做了三十六种共存离子的影响实验，多数常见离子不干扰铝的测定，此法主要用于水中铝的测定，家Gr~(3+), Ln~(3+), Ti~(4+), Sn~(4+), Be~(2+)这些离子对铝离子测定的干扰尽管很大，但它们在水中的含量很低，因此可以不考察其干扰作用，F~-和PO_4~(3-)都易与铝离子形成配合物，但水中F~-，PO_4~(≡)含量很小，一般情况下不干扰铝的测定。本法主要考虑了Cu~(2+), Fe~(3+)对铝测定的干扰，用硫脲掩蔽Cu~(2+), 用抗坏血酸掩蔽Fe~(3+), 得到了满意的结果。应用本法测定实际水样，五次测定结果的相对标准偏差为5％，用标准加入法测得其回收率在92～104％之间。由以上工作可以看出，由于CPB的加入，使得Al-CAS-CPB三元体系的摩尔吸光系数较Al-CAS二元配合物的大3.5 倍，最大吸收波长也产生了较大的红移，因此，有必要进一步探讨一下此三元体系的反应机理。目前，阳离子表面活性剂对显色反应作用机理的研究较多，但尚没取得一致的见解，这些研究结果可以归纳为四个方面，1．拟均相萃取模型，2．电荷胶米模型，3．双区作用模型，4．配位体－配位体相互作用的理论和协同微扰机理。本文以Al-CAS-CPB体系作为代表，通过Al-CAS-CPB三元配合物的结构、吸收光谱的变化和表面能力测定的结果探讨了CPB作用机理。利用电泳和离子交换实验说明了Al-CAS-CPB的配阴离子，利用平衡移动法和直线法测得Al：CAS的配位电为1：2，用等摩尔连续变换法测定Al：CPB的配位电为1：4，因而配合物的组成比Al：CAS：CPB＝1：2：4。最后推出此配合物的可能结构。从CAS、Al-CAS、Al-CAS-CPB的结构出发，研究了配位体之间相互作用对CAS中大共轭π键中π－电子流动难易的影响，成功地解释了Al-CAS-CPB最大吸收波长产生红移的原因。通过对CAS溶液浓度与三元配合物最大吸收波长、吸光度影响的研究，说明CPB有三个作用，一是与Al、CAS反应形成三元配合物，同时提高了Al与CAS的配位电；二能与CASi试剂产生缔合作用；三是能够形成胶米；增大了三元配合物在水中的溶解充，这三种作用相互制约，并与Al、CAS及CPB之间的摩尔比有关。通过对配合物吸光度，表面张力和表面活性剂浓度关系的研究及CMC值前后此三元体系吸光度、表面张力变化的比较，结果表明，单分子和形成胶米的表面活性剂同样具有增敏作用，这与郑用熙提出的双区作用机理相一致。在CMC值前，单分子表面活性剂与Al、CAS形成三元配合物而起增敏作用，在CMC值以后，CPB与Al、CAS形成胶米配合物而产生增敏作用。最后，讨论了三元体系的最大吸收波长与表面活性剂浓度的关系，结果表明，随CPB浓度的增大，三元体系的最大吸收波长发生蓝移。产生蓝移的原因可以从结构化学的角度得到解释，导致最大吸收波长不同的原因是在CMC前后，Al-CAS-CPB三元配合物所处的微环境不同。对稀酸性水体中铝形态的分离分析及低浓度铝的测定已有人进行研究，普遍认为无机单核铝是致毒因子，因此无机单核铝的浓度较其实际浓度对生命物质的意义更为重要。本文基本上采用Dirscoll形态分离法进行测定土壤酸性浸出液中铝的形态，用Al-CAS-CPB三元显色反应测定各部分铝形态和浓度。其各部分铝形态的分离如下：总活性铝（Al_r）：将样品用0.2um微孔滤膜过滤，用1N HCl将样品酸化为pH等于1，持续24小时，用Al-CAS-CPB测得其中铝含量。总单核态铝（Ala）：将样品用0.2um微孔膜过滤，直接用Al-CAS-CPB法测定铝量。稳定单核铝（Alo）：稳定的单核铝和不稳定的单核铝通过阳离子交换树脂分离。稳定单核铝通过阳离子树脂后，不能被树脂交换，用Al-CAS-CPB法可以直接流出液中铝量为Alo。不稳定单核铝(Alb)为Ala-Alo。在铝形态的分离过程中，我们使用了过滤和树脂交换二种分离方法。对此做了较详细的条件实验。研究了pH值对滤液中铝的影响，随pH值升高，滤液中铝量减小，这就说明，pH值升高，可能形成某些不能通过滤膜的形态，另外也可能是由膜吸附引起的。本文还比较了用静态平衡法和动态法阳离子交换分离稳定单核铝和不稳定单核铝，指出静态平衡法受到溶液pH值的制约，平衡所需时间过长，容易引起溶液中铝形态的变化和沾污，而动态法则能克服这些缺点，因此在实验中采用动态法。把形态分离的方法应用到土壤酸性浸提液中，结果表明，不稳定的单核铝形态(Alb)远远大于稳定的单核铝形态，而不稳定的单核铝形态中含有对植物的致毒因子，因而酸雨能导致森林死亡，农作物发育不良。

IL-2基因的突变及其与肠毒素融合基因的克隆和表达

由金黄色葡萄球菌分泌到胞外的单亚基蛋白中有肠毒素A和B。近年来两种毒素在肿瘤治疗研究方面取得了很大进展。白介素-2作为靶向分子，在抗肿瘤的药物中很有应用前景。本文分别对肠毒素A、肠毒素B和白介素-2进行了克隆和表达，并将白介素-2（125Ala）分别与肠毒素A227AI。肠毒素B进行了融合表达。从筛选到的天然金黄色葡萄球菌STSw的基因组中，通过PCR方法扩增出seb基因，同时突变了该基因两端几个稀有密码子。并将其克隆到7ZTS载体上进行表达，表达量占细胞总蛋白的33.5％。以seam基因为模板，通过重叠PCR将其227位天冬氨酸突变为丙氨酸，以降低其毒性。该突变基因重组到7ZTS载体中，并在JM109（DE3）中表达，表达量占细胞总蛋白的51.5％。通过重叠PCR法，对人的IL-2基因进行定点突变。共突变60个碱基，涉及51个氨基酸，其中第125位的半肤氨酸被突变为丙氨酸。该基因在大肠杆菌中表达量占总蛋白的30％。分别对上述三个工程菌的表达条件进行了探索。先制备出融合基因，再对融合基因进行表达，得到两种融合蛋白。它们是以6个甘氨酸和1个苏氨酸为链，将IL一2（125Ala）与肠毒素A227（Ala）、B分别连接起来，即IL-2（125Ala）-SEA227（Ala）和IL-2（125Ala）-SEB二者在大肠杆菌中表达量分别占总蛋白的10％和12％。以上实验结果为将几种蛋白开发成抗肿瘤靶向药物奠定了坚实基础。