Particulate peptidoglycan in seawater determined by the silkworm larvae plasma (SLP) assay

Peptidoglycan (PG) is a biopolymer found exclusively in the cell wall of bacteria. Recent chemical analysis of particulate organic matter suggests that a major amount of the muramic acid, an amino sugar present only in PG, could not be accounted for in terms of bacterial cells (Benner and Kaiser, 2003); however, data on particulate PG is quite sparse. In the present study, conducted in 1996, the PG was examined at 5 sampling sites in the northwestern Pacific Ocean, and in natural seawater cultures. Particulate PG, which was concentrated using a 96-well filtration plate equipped with Durapore filters (pore size, 0.22 μm), was measured by the silkworm larvae plasma (SLP) assay. The PG concentration generally decreased with depth and correlated significantly with bacterial abundance throughout the entire water column. However, the ratio of particulate PG to bacterial abundance varied with depth. The average ratio was 0.61 ± 0.53 (average ± SD, n = 40) between 50 and 2000 m, which agreed with the bacterial cellular PG content from 0.63 to 1.1 fg cell⁻¹ obtained in seawater cultures. On the other hand, the ratios of PG to bacteria from the surface to 50 m (3.7 ± 2.6, n = 29) and below 2,000 m (2.1 ± 1.7, n = 7) were significantly higher than that between 50 and 2,000 m. These results may suggest that, in the surface and deep layers, a significant fraction of particulate PG was present in bacterial detritus, whereas this fraction was reduced in the middle layer.     

Detection of DNA damage in mussels and sea urchins exposed to crude oil using comet assay

The single-cell microgel electrophoresis assay or the comet assay was used to evaluate DNA damage of dispersed crude oil on sea urchins (Strongylocentrotus droebachiensis) and mussels (Mytilus edulis L.). Sea urchins were exposed to 0.06 and 0.25 mg/L dispersed crude oil in a continuous flow system, while the mussels were exposed to 0.015, 0.06 and 0.25 mg/L dispersed crude oil. Sea urchin coelomocytes and mussel haemocytes were sampled after 4 and 5 weeks exposure, respectively. In the sea urchin coelomocytes, there was a significant concentration-related increase in the percentage of DNA in comet tail. In mussel haemocytes, there was a significantly higher percentage of DNA in comet tail for all treatments compared to the control. The responses were concentration-related up to 0.06 mg/L oil. The two highest exposure concentrations of mussels were not significantly different from each other. These results indicate that the comet assay can be used for biomonitoring of DNA damage in marine invertebrates following oil contamination.     

藓羽藻(Bryopsis hypnoides)核酮糖-1，5-二磷酸羧化酶／加氧酶的分离与活性测定

采用硫酸铵分部沉淀与凝胶过滤的方法，进行藓羽藻Rubisco的分离研究。结果表明，分离的藓羽藻Rubisco经SDS-聚丙烯酰胺凝胶电泳检测呈两条清晰条带，分别为Rubisco大亚基与小亚基；与菠菜相比，藓羽藻Rubisco大亚基分子量与菠菜基本相同，而小亚基较之稍大一些。藓羽藻Rubisco活力测定结果表明，Rubisco分离过程中用硫酸铵分部沉淀后活力降低许多，分离后活力有所上升，但仍比粗提液活力弱；在Rubisco活力测定过程中，藓羽藻Rubisco的活化温度与其它物种Rubisco活化的温度不同，在低温下活化效果较好。这些结果说明Rubisco的酶活力受硫酸铵的影响而且藓羽藻Rubisco相对陆地高等植物结构不稳定。     

CELLULOSE DECOMPOSTION IN TROPICAL PEAT SWAMPS

Given that organic soil is a complex substrate and there are many environmental factors which directly or indirectly control its decomposition processes, the use of standard substrate simplify the system in that the effect of substrate quality could be eliminated and influence of certain environmental conditions such as edaphic factors, acidity and moisture could be focused on. In addition to the forest floor, decomposition potential down the peat profile can also be examined. Cotton strip assay was used to estimate decomposition potentials in tropical peat swamp occupied by different Shorea Albida peat swamp forest communities, The 'Alan Batu' , the ' Alan Bunga' , the 'Alan Padang' and the ' mixed Alan' forest communities.Greatest decay rates on the peat surface took place during the wet period. The moist condition of the wet months appeared to favour the growth and stimulate activities of decomposer population and soil invertebrates. Generally, 50% of cotton tensile loss is achieved after four weeks     

山东沿海海藻抗肿瘤活性的筛选

于1997年4月和2000年5月对山东沿海海藻进行较系统的采集，对其中39种海藻的96个样品采用高通量方法进行选择性细胞毒筛选，结果表明，小粘膜藻（Leathesia dif-formes)、多管藻（Polysiphonia urcedata)、萱cytosiphon lomentarius)、海萝（Gloiopeliis fur-cata)、叉开网翼藻（Dictyopteris diuaricata)、点叶菜（Punctaria latifolia)等对KB细胞或HT-29细胞具有选择性抑制活性。局醇、氯仿的提取效率较高，多管藻的乙醇、氯仿提取物，萱藻的乙醇提取物和叉开网翼藻的正己烷提取物都有强的选择性细胞毒活性。     

镉胁迫对大弹涂鱼(Boleophthalmus pectinirostris)血细胞遗传损伤的研究

以大弹涂鱼为研究对象,应用单细胞凝胶电泳技术并结合外周血基因组DNA琼脂糖凝胶电泳,研究了镉胁迫对大弹涂鱼外周血细胞的遗传损伤。结果表明:(1)镉对大弹涂鱼外周血细胞是遗传毒性而非细胞毒性,并且产生的遗传损伤存在显著(P0.01或P0.05)的剂量效应,染毒1h的大弹涂鱼的全长和尾长与浓度的相关方程分别是y=29.592x-10.576(r2=0.9786),y=28.417x-14.859(r2=0.9857),染毒2h的大弹涂鱼的全长和尾长与浓度的相关方程分别是y=32.044x-5.0235(r2=0.941),y=29.911x-9.539(r2=0.9635)。(2)DNA的损伤程度和污染胁迫之间存在着时间效应。以上结果表明,DNA损伤可作为大弹涂鱼受镉胁迫时的生物指标。     

瘤状软骨凹顶藻化学成分研究

采用硅胶柱色谱以及Sephadex LH-20凝胶色谱手段,对海洋红藻瘤状软骨凹顶藻(Chondrophycus papillous Garbary et Harper)进行化学成分研究,分离得到5个化合物.通过MS、NMR等方法对得到的化合物进行结构确证,分别鉴定为邻苯二甲酸二丁酯(Ⅰ),邻苯二甲酸二异辛酯(Ⅱ),胆甾醇(Ⅲ),植醇(Ⅳ)和4-羟基苯甲醛(Ⅴ).所有化合物均为首次从该种海藻中分离得到.通过MTT法对得到的单体化合物进行细胞毒活性筛选,结果显示所有化合物在10 mg/L浓度下均无明显活性.     

Chemical constituents of marine medicinal mangrove plant Sonneratia caseolaris

Twenty-four compounds including eight steroids (1-8), nine triterpenoids (9-16, 24), three flavonoids (20-22), and four benzenecarboxylic derivatives (17-19, 23) were isolated and identified from stems and twigs of medicinal mangrove plant Sonneratia caseolaris. The structures of the isolated compounds were determined by extensive analysis of their spectroscopic data. Among these metabolites, compounds 1, 4-20 and 22-24 were isolated and identified for the f'urst time from S. caseolaris. In the in vitro cytotoxic assay against SMMC-7721 human hepatoma cells, compound 21 (3',4',5,7-tetrahydroxyflavone)exhibited significant activity with IC50 2.8 μg/mL, while oleanolic acid (14), 3,3'-di-O-methyl ether ellagic acid (18), and 3,3',4-O-tri-O-methyl ether ellagic acid (19) showed weak activity. None of these compounds displayed significant antibacterial activites.     

Determination of the Platinum-Group Elements and Gold in Twenty Rock Reference Materials by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) after Pre-Concentration by Nickel Sulfide Fire Assay

The platinum-group elements (PGE) and gold have been determined in twenty international rock reference materials by inductively coupled plasma-mass spectrometry (ICP-MS) after pre-concentration by a nickel sulfide fire assay. It was possible to achieve determination limits for a 50 g sample that ranged from 1 pg g^-1 (Rh) to 23 pg g^-1 (Au). Compared to published certified and recommended values for rock reference materials, the trueness of the method was found to be good. However, in some cases we observed large deviations for all elements in the sub 10 ng g^-1 range within individual reference sample splits. Our results show that the PGE and Au are inhomogeneously distributed in the reference materials analysed here, where they are present in low concentrations, using 50 g test portions.     

罗氏沼虾线粒体锰超氧化物歧化酶的克隆表达与功能研究

罗氏沼虾(Macrobrachium rosenbergii)是我国重要的经济虾类之一。近年来, 细菌性感染造成罗氏沼虾养殖业病害频发, 经济损失巨大。因此了解其免疫机制对于指导疾病防控至关重要。线粒体锰超氧化物歧化酶(mitochondrial manganese superoxide dismutase, mMnSOD)被认为是抵御氧化应激的第一道防线, 在先天性免疫中具有至关重要的作用。目前, 甲壳动物中mMnSOD的免疫功能尚不清楚。为此, 本研究克隆了罗氏沼虾mMnSOD基因(mMnSOD of M. rosenbergii, MrmMnSOD), 制备了多克隆抗体, 分析了嗜水气单胞菌(Aeromonas hydrophila)感染下, MrmMnSOD在不同组织中的表达模式。结果显示, 肝胰腺和肠组织中MrmMnSOD的基因表达水平分别在感染后3h和6h达到最大; 组织免疫荧光分析显示, 肝胰腺和肠组织中MrmMnSOD均在感染后12h达到最大荧光强度。以上结果表明, mMnSOD参与了罗氏沼虾对嗜水气单胞菌的免疫应激反应。进一步的蛋白抑菌实验表明, MrmMnSOD可显著抑制大肠杆菌(Escherichia coli)、嗜水气单胞菌、副溶血弧菌(Vibrio parahaemolyticus)、金黄色葡萄球菌(Staphylococcus aureus)和无乳链球菌(Streptococcus agalactiae)的生长, 推测该蛋白可能属于免疫相关分子, 可通过抑菌反应发挥免疫功能。当前的研究结果进一步丰富了甲壳动物先天性免疫基础理论, 也可为今后罗氏沼虾的病害防控和药物研发提供新的靶点参考。