黄海冷水团海域浮游植物磷胁迫的季节变动

The Yellow Sea is located between the China Mainland and the Korean Peninsula, representing a typical shallow epicontinental sea. The Yellow Sea Cold Water Mass（YSCWM） is one of the most important physical features in the Yellow Sea. The characteristics of vertical profiles and seasonal variations of biogenic elements in the YSCWM may lead the variations of nutrient availability（e.g., phosphorus） and phosphorus stress of phytoplankton. In this study, the authors surveyed the seasonal variations of phytoplankton phosphorus stress with emphasis on the effect of the YSCWM during the four cruises in April and October 2006, March and August 2007. Using both bulk and single-cell alkaline phosphatase activity（APA） assays, this study evaluated phosphorus status of phytoplankton community, succession of phytoplankton community and ecophysiological responses of phytoplankton to phosphorus in the typical region of the YSCWM. With the occurrence of the YSCWM, especially the variations of concentration of dissolved inorganic phosphorus（DIP）, the results of bulk APA appeared corresponding seasonal variations. Along Transects A and B, the mean APA in August was the highest, and that in March was the lowest. According to the ELF-labeled assay＇s results, seasonal variations of the ELF-labeled percentages within dominant species indicated that diatoms were dominant in March, April and October, while dinoflagellates were dominant in August. During the four cruises, the ELF-labeled percentages of diatoms except Paralia sulcata showed that diatoms were not phosphorus deficient in April 2006 at all, but suffered from severe phosphorus stress in August 2007. In comparison, the ELF-labeled percentages of dinoflagellates were all above 50% during the four time series, which meant dinoflagellates such as Alexandrium and Scrippsiella, sustained perennial phosphorus stress.     

Effect of sodium chloride and cadmium on the growth,oxidative stress and antioxidant enzyme activities of Zygosaccharomyces rouxii

Zygosaccharomyces rouxii is a salt-tolerant yeast species capable of removing cadmium(Cd) pollutant from aqueous solution. Presently, the physiological characteristics of Z. rouxii under the stress of sodium chloride(NaCl) and Cd are poorly understood. This study investigated the effects of NaCl and Cd on the growth, oxidative stress and antioxidant enzyme activities of Z. rouxii after stress treatment for 24 h. Results showed that NaCl or Cd alone negatively affected the growth of Z. rouxii, but the growth-inhibiting effect of Cd on Z. rouxii was reduced in the presence of NaCl. Flow cytometry assay showed that under Cd stress, NaCl significantly reduced the production of reactive oxygen species(ROS) and cell death of Z. rouxii compared with those in the absence of NaCl. The activities of superoxide dismutase(SOD), catalase(CAT), and peroxidase(POD) of Z. rouxii were significantly enhanced by 2%–6% NaCl, which likely contributed to the high salt tolerance of Z. rouxii. The POD activity was inhibited by 20 mg L-1Cd while the SOD and CAT activities were enhanced by 8 mg L-1 Cd and inhibited by 20 mg L-1 or 50 mg L-1 Cd. The inhibitory effect of high-level Cd on the antioxidant enzyme activities of Z. rouxii was counteracted by the combined use of NaCl, especially at 6%. This probably accounted for the decrease in Cd-induced ROS production and cell death of Z. rouxii after incubation with NaCl and Cd. Our work provided physiological clues as to the use of Z. rouxii as a biosorbent for Cd removal from seawater and liquid highly salty food.     

几种益生菌对大菱鲆幼鱼生长及消化酶活性的影响

作者以初体质量为(4.80±0.11)g 的大菱鲆(Scophthalmus maximus)为研究对象,在循环水水族箱中进行60 d 饲喂实验,研究饵料中添加单一益生菌和复合益生菌对大菱鲆生长及消化道酶活性的影响.以基础饲料为对照组,在基础饲料中分别添加枯草芽孢杆菌(Bacillus subtilis)、地衣芽孢杆菌...     

江河能“消化”生活污水吗？——记对嘉陵江段河流自净能力的研究性学习活动

在地理新课改的实践中,行为主义学习理论将地理课堂和实践操作紧密联系起来。地理作为一门实践性很强的学科,知识的获取并不能局限于课堂中的教学,我们应当跳出传统课堂的框架,结合有效的乡土资源,开设“第二课堂”,让学生通过“做中学”,获取直接经验的积累。     

温岭市“四个结合”推进消化利用批而未供、供而未用土地工作

一是调查摸底和统计分析相结合。该市要求各镇（街道）根据每年度农转用（征收）批次清单和已供建设项目台账,集中力量,落实责任人员．对1999—2010年已经办理农转用手续的土地和2007—2010年已供土地进行全面摸排：建立批而未供台账和供而未用台账。对每个批次中的未供土地逐项进行核对检查,按照绿化道路及安全间距等无法利用的土地、未供先用的违法用地和因其他原因造成的转而未供的土地等3种类型分别进行统计与处理;     

示波极谱法测定人发中的锌、铜和铁

儿童生长发育、免疫功能和智力发育与人体必需的微量元素关系密切。由于头发易于取样和保存，且毛发中元素的含量是血和尿中的10～15倍。因而，头发分析日益受到人们的重视。近年来，相继出现了分析人发中微量元素的各种方法—AAS法、NAA法、XRF法、ICP—AES法等。而在同一消解液中，进行催化示波极谱法测定人发中Zn．Cu、Fe尚未见报道。本文研究、对比了不同的湿法消化体系，在同一份消解液中，进行人发中Zn、Cu、Fe的极谱测定。     

2个重组海带α-碳酸酐酶(CA)的酶活性比较研究

为了探究海带(Saccharina japonica)α-CA1和α-CA2是否具有催化CO₂的可逆水合反应和酯酶活性,作者通过原核表达得到这两种α-CA的可溶性的异源重组蛋白。分别用电极法和酯酶活性检测法来检测重组α-CA1(rα-CA1)和rα-CA2的水合酶活性和酯酶活性,结果发现,rα-CA1的水合酶活性(1.52±0.120 U/mg)几乎是rα-CA2(0.54±0.046 U/mg)的3倍,表明rα-CA1催化CO₂的水合能力明显大于rα-CA2。而两者的酯酶活性并没有显著的差别(rα-CA1比活力:0.697±0.176 U/g,rα-CA2比活力:0.743±0.129 U/g),说明催化乙酸对硝基苯酯(p-NPA)生成对硝基苯酚(p-NP)的能力是没有显著差别的。实验结果证实这2个α-CA为功能蛋白,可能参与海带无机碳吸收和储存过程,因此,本研究为海带无机碳吸收和储存机制的解析提供了生物化学依据。     

毛乌素沙地火电厂周边不同类型生物结皮酶活性及其影响因素北大核心CSCD

选取宁东能源化工基地典型火电厂周边广泛分布的3类生物结皮作为研究对象,探究工矿区生物结皮富集大气降尘重金属对酶活性的影响及其影响深度,在对比分析富集大气降尘过程中土壤理化性质、酶活性及重金属含量变化的基础上,采用相关分析、冗余分析方法探讨了生物结皮各层次土壤酶活性与土壤重金属含量和土壤理化性质之间的相关关系。结果表明:(1)沿藻结皮—混生结皮—藓结皮的演替方向,结皮层土壤有机碳(SOC)、全氮(TN)及全磷(TP)含量显著提升,土壤容重和pH降低;随土层深度增加,土壤理化性质变化不显著。(2)3类生物结皮对源自大气降尘的重金属元素均具有显著的表层富集作用,富集量藓结皮>混生结皮>藻结皮;结皮层重金属污染程度高于下层土壤。(3)4种土壤酶活性沿藻结皮—混生结皮—藓结皮的演替方向呈现一致的规律性,表现为藓结皮>混生结皮>藻结皮。(4)部分重金属元素Zn、Pb、Cd和土壤理化性质如容重、pH、SOC、TN等是影响土壤酶活性的主要因子,但相较于重金属元素,土壤理化性质对酶活性影响更大。     

不同模式凡纳滨对虾(Litopenaeus vannamei)养殖池塘沉积物酶活性及其微生物群落结构分析

采用现场测定、磷脂脂肪酸(PLFA)法及基质脱氢酶活性测定等方法,对4种不同养殖模式的凡纳滨对虾池塘的水质、沉积物酶活性及微生物群落结构进行了分析和研究。结果表明:养殖末期,凡纳滨对虾淡水混养和海水混养池塘水质较好,海水集约化池塘水质最差;其中海水集约化池塘沉积物基质中有机质含量、微生物生物量、微生物活性和酶活性都很高,真菌、G+菌的相对含量则很低。主成分分析(PCA)表明:第一主成分主要与脲酶、有机质含量、微生物活性、总PLFA、B/F有显著的正相关关系(r>0.9),而与Gram+/Gram-、pH、18:1ω9C/T、单不饱和/支链却存在显著的负相关关系(r>0.9);第二主成分主要与脱氢酶有显著正相关关系(r>0.8),四种池塘在PCA图中分散开,说明其微生物群落结构及环境状况存在明显差异。