4种滑叶铁线莲基因组DNA提取方法比较(英文)

[目的]对4种滑叶铁线莲基因组DNA提取方法进行比较研究,建立滑叶铁线莲最适的DNA提取方法。[方法]以滑叶铁线莲叶片为材料,比较改良CTAB法Ⅰ、改良CTAB法Ⅱ、改良CTAB法Ⅲ、改良SDS法这4种基因组DNA提取法在提取的DNA纯度、浓度和提取时间等方面的不同。[结果]4种方法都可提取滑叶铁线莲基因组DNA。改良CTAB法Ⅰ提取DNA纯度最高,但浓度最低且提取时间最长;改良SDS法提取DNA浓度最高,所需时间较短,但纯度较低;改良CTAB法Ⅲ提取所需时间最短。[结论]建立了铁线莲最适DNA提取方法,为运用分子生物学手段对其研究提供支持。     

金黄色葡萄球菌基因组DNA提取方法的比较

为寻求一种较为实用的金黄色葡萄球菌（Staphylococcus aureus）基因组DNA提取方法,对酶解法、十二烷基硫酸钠（Sodium dodecyl sulfate,SDS）法、FDA法、热裂解法等常见的4种不同提取方法进行了改良和比较.结果表明,4种方法中,SDS法提取的DNA质量最好,检测灵敏度高,当金黄色葡萄球菌的DNA稀释至2.95 pg或更少时,SDS法还能够通过PCR将其检测出来;并且该方法的稳定性好,经济性高,是金黄色葡萄球菌基因组DNA理想的提取方法.     

Mesohabitat associations of the threatened San Marcos salamander (Eurycea nana) across its geographic range

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黄河水沉淀后水质对滴灌灌水器堵塞的影响

利用2013年5月—10月和2014年7月—11月的实测数据,分析了乌海市不同功能的三个典型沉淀池(如意湖、林业湖和朝阳湖)的浊度、细菌总数、叶绿素a、总氮、总磷五项水质指标的沉淀、过滤效率,利用灌水器堵塞野外调查数据并结合堵塞物电镜扫描图片,探讨了黄河水经过平流沉淀+网式过滤组合模式处理后仍会造成灌水器堵塞的原因。结果表明:各沉淀池浊度的沉淀和过滤效率均较高,其中如意湖的沉淀效率最高,平均去除率为63%;2013年朝阳湖的过滤效率最高,为60.53%,各沉淀池水质指标的过滤效果普遍较差。黄河水经沉淀过滤后仍会造成灌水器堵塞,其主要原因与细小颗粒物和微生物形成的絮状结构有关,建议对原有沉淀、过滤措施提出改进,经一、二级沉淀后在泵房内改用叠片式砂过滤器。     

Ridge to reef modelling for use within land–sea planning under data‐limited conditions

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In vivo and in vitro protein digestibility in juvenile bagrid catfish Mystus nemurus (Cuvier and Valenciennes 1840) fed soybean meal‐based diets

In vivo and in vitro protein digestibility of 0% to 60% soybean meal protein (SBM) substitution from fishmeal protein was conducted for bagrid catfish Mystus nemurus juveniles. Seven experimental diets containing 35% protein and 15% lipid were fed to bagrid catfish to determine the in vivo protein digestibility. In vitro methods were determined using pH stat, pH shift, spectrophotometric assay and sodium dodecyle sulphate polyacrylamide gel electrophoresis (SDS‐PAGE) with different enzyme mixtures (crude intestinal extract of bagrid catfish, Lazo 1‐enzyme, Hsu 3‐enzyme, Saterlee 4‐enzyme). In vivo and in vitro protein digestibility decreased with increased SBM protein substitution with highest tolerance level of 10% (in vivo). pH stat and pH drop methods showed the highest degree of hydrolysis (DH) and relative protein digestibility (RPD) using Saterlee 4‐enzyme system. However, pH stat method showed highest correlations (r² = 0.9263) with the in vivo results using crude intestinal enzyme extract compared to other enzyme systems. The highest correlation of the in vitro methods using crude intestinal enzyme extracts of bagrid catfish was determined using spectrophotometric assay (r² = 0.9284) followed by pH stat (r² = 0.9263), SDS‐PAGE (r² = 0.8348) and pH drop (r² = 0.6777). All the in vitro methods tested are suitable to rapidly determine protein digestibility for bagrid catfish except for pH drop.     

Bacterial community composition of sediments from a milkfish Chanos chanos Forsskål farm

Bacterial communities in sediments underneath milkfish cages and adjacent off‐cage areas in Bolinao, Lingayen Gulf, West Philippine Sea were characterized using PCR‐denaturing gradient gel electrophoresis to assess influence of the fish farming to the sediments. The sediments in the fish cage (FC) area showed anoxic conditions [redox potential of ?165 to ?213 mV and acid‐volatile sulphide‐sulphur (AVS‐S) of 0.55–1.88 mg g^?1 (dry weight)] compared to the relatively oxic off‐cage area [redox potential of 72–81 mV and AVS‐S of 0.09–0.14 mg g^?1 (dry weight)]. The composition of the microbial populations revealed influence of the fish feed sedimentation with higher dominance of putative sulphate‐reducing bacteria (SRB) in the FC area. Compositions of the bacterial taxa showed dominance of the Bacteroidetes group and Deltaproteobacteria. The results suggest that the fish feeds created a new suitable environment, in which reductive microorganisms such as SRB, ferric‐ion‐reducing bacteria and nitrate‐reducing bacteria can thrive. Organic load from the feed and quantity of its leftover constituents may be the key factors that influence the structure of the bacterial community in the sediments of the milkfish farms.     

不同方法从绞股蓝种子中提取基因组DNA的研究

以绞股蓝种子为研究材料,采用改良的CTAB法、改良的SDS法和高盐低pH法对绞股蓝基因组DNA进行提取,对提取效果采用紫外分光光度计检测、琼脂糖凝胶电泳和RAPD进行综合比较分析。结果表明:3种提取方法所获得的DNA,其OD260/OD280多数都在1.80~2.00,琼脂糖凝胶电泳结果也显示DNA的质量很好,改良的SDS法提取效率显著好于改良的CTAB法和高盐低pH法;而且改良的SDS法提取的DNA的RAPD图谱条带最亮、最清晰。因此,从DNA产量、质量等方面综合考虑,改良的SDS法为绞股蓝种子DNA提取的有效方法。     

平流二沉池中计及温差影响的异重流数值模拟

【目的】在同时考虑进水与池内水的污泥质量浓度差异和温度差异的条件下,对平流式二沉池内的异重流现象进行数值模拟,重点研究异重流对池内流场及污泥沉降规律的影响,为优化沉淀池结构设计及提高沉淀池工作效率提供理论支持。【方法】选取Mixture模型和RNGκ-ε2方程紊流模型,设初始时刻二沉池内水为清水,进水为含一定质量浓度污泥的污水,并通过设置池内水与进水的不同温差模拟夏季与冬季环境,利用模拟数据分析不同时刻各工况下异重流的演变规律。【结果】池内水与进水的单纯污泥质量浓度差异会产生下异重流,小温差低温水与夏季大温差低温水进入均会导致下异重流产生,温差增大,下异重流作用更为明显;高温水进入会同时产生上异重流与下异重流,冬季温差高温水进入时上异重流起主导作用,异重流产生的旋流作用明显,对沉淀池工作效率的影响很大。【结论】温差异重流与污泥质量浓度差异重流本质均为密度差异,低温水进入增强下异重流,高温水进入削弱下异重流,温度影响会消失,污泥质量浓度差异重流作用时间更长。