3种淡水环境中低核酸含量细菌的滤过性

【目的】增加低核酸含量(LNA)细菌与过滤性细菌之间的认识。【方法】采用流式细胞技术(FCM)、变性梯度凝胶电泳(DGGE)及统计学分析研究3种典型淡水环境中细菌群落与滤过性。【结果】LNA细菌与过滤性细菌在数量上具有很好的相关性(y=0.646x+22.42,R2=0.984,P0.01),细菌的滤过性不仅与细菌大小有关,还与细胞整体形状及其伸缩性有关;细菌群落组织与LNA细菌比重呈负相关性,而与HNA细菌呈正相关性。【结论】0.45μm膜过滤对水样微生物群落中的LNA细菌具有极强的筛选效果;细菌群落组织与其基于流式细胞技术测定的基因含量具有密切联系。     

饮用水微生物的安全快速检测

【目的】为了更好地分析饮用水中的微生物含量。【方法】利用流式细胞术(Flowcytometry,FCM)、ATP测定方法检测瓶装无气饮用水中的微生物数量、可同化有机碳(Assimilable organic carbon,AOC)含量以及微生物活性,并将检测结果与传统的饮用水微生物检测技术相对照。【结果】FCM方法可快速区分水样中的活性细菌和非活性细菌,AOC含量反映了水样中微生物再生能力;而ATP检测方法也能比异养细菌平板计数法(Heterotrophic plate count,HPC)更好地反映瓶装无气饮用水中的实际微生物含量。【结论】FCM、ATP测定方法要明显优于依赖于培养的传统方法。     

不同季节温升条件下余氯对桡足类的毒性

为探明桡足类对滨海电厂冷却水中余氯的忍受能力,在各季节于室内对采自乐清湾的12种桡足类进行30 min不同升温幅度(△T)(0、4.0、8.0、12.0℃)下的余氯胁迫,观察桡足类在24h后的死亡率,用概率单位法计算其余氯半致死浓度(Median lethal concentration,LC50).结果表明各季节桡足类余氯LC50随△T增大而显著降低(P＜0.001),且.多数种类呈显著线性回归关系(P＜0.05).对于哲水蚤目桡足类,余氯LC50随其粒径增大而升高.同一种桡足类在相同△T下,随适应水温升高,余氯LC50显著降低(P＜0.01).亚热带海区夏季自然水温较高,冷却系统轻微的升温即可加剧余氯对其的毒性.若以LC50×0.5来确定桡足类余氯安全浓度,则春、秋、冬季暴露时间≤30 min、△T≤12.0℃时,其余氯安全浓度分别为0.21-0.86 mg/L、0.26-0.86 mg/L、0.32-4.55 mg/L;夏季暴露时间≤30 min、△T≤8.0℃时,其余氯安全浓度为0.15-0.41 mg/L.当前电厂加氯浓度偏高对冷却水中桡足类造成较大影响,但排出水中余氯对其影响不大.基于生态安全考虑,根据对余氯较敏感的小型桡足类在不同季节下的余氯安全浓度,建议亚热带滨海电厂夏季余氯排放浓度不超过0.15 mg/L,其余季节不超过0.20 mg/L.     

球形红细菌厌氧降解2,4-二硝基甲苯

【目的】研究不同环境条件对2,4-二硝基甲苯(2,4-DNT)生物降解的影响。【方法】采用光合细菌球形红细菌在温度为30 °C的光照培养箱中厌氧降解2,4-DNT,并用高效液相色谱仪测定其浓度。【结果】去除2,4-DNT的最佳条件是初始浓度40 mg/L、初始pH 7.0和接种量15%。另外,2,4-DNT在菌体延滞期被细胞吸收,然后在指数期作为碳源被降解。2,4-DNT的去除率在72 h达到98.8%。从液相色谱图中观察到有2种中间代谢产物,但在120 h内产物被逐渐降解。2,4-DNT的去除动力学符合一级速率模型。【结论】不同条件下2,4-DNT的去除率表明球形红细菌能有效降解2,4-DNT。     

有机溶剂胁迫处理对菌株Bacillus subtilis OST23a产胞外多糖的影响

【目的】研究有机溶剂胁迫处理对菌株分泌胞外多糖的影响并确定最佳条件。【方法】利用分泌抗氧化活性胞外多糖海洋细菌Bacillus subtilis OST23a及其突变菌株UD292为出发菌株,在考察菌株有机溶剂耐受性的基础上,测定不同浓度正己烷胁迫处理不同时间后该菌株抗氧化胞外多糖产量。【结果】结果表明最佳胁迫处理浓度和时间分别为3%和6 h,此时Bacillus subtilis OST23a和菌株UD292胞外多糖分泌量分别从9.02 mg/L和43.92 mg/L显著提高到52.97 mg/L和201.81 mg/L,且胞外多糖的抗氧化性能无显著变化。Bacillus subtilis OST23a和菌株UD292连续传代试验结果表明菌株遗传性状较稳定。【结论】有机溶剂胁迫可以提高细菌分泌胞外多糖的能力,在微生物育种方面有潜在的应用。     

乙酸驱动条件下粪产碱杆菌Y5的碳氮共脱除特性

【目的】研究微生物的碳氮共脱除特性及其关键影响因素。【方法】以乙酸为唯一碳源分离获得的碳氮共脱除菌株Y5为模式菌株,分析菌株Y5的16S r RNA基因序列、碳源和氮源去除动力学,以及碳源种类、碳氮比(C/N)、溶解氧浓度(DO)、温度和p H等影响效果。【结果】菌株Y5归属于粪产碱杆菌。与葡萄糖及多种有机酸相比,菌株Y5在以乙酸为唯一碳源的条件下具有较高的TOC和NH4+-N去除速率。在好氧条件下,当起始TOC浓度为1 000 mg/L,氨氮浓度为110 mg/L时,菌株Y5的NH4+-N、TOC和总氮(TN)去除率分别达99.54%、92.95%和86.55%,最大NH4+-N、TOC和TN去除速率分别为903.58、505.81和406.03 mg/(L·d)。【结论】粪产碱杆菌Y5在以乙酸为唯一碳源的条件下具有较强的碳氮共脱除能力,其最佳反应条件为:C/N=10,p H 7.0-8.0,溶氧6.20 mg/L,反应温度为30°C。     

一株PCBs降解菌的降解特性及发酵条件优化

【目的】针对一株多氯联苯的高效降解菌,考察其对多氯联苯(PCBs)的降解特性,并对降解条件进行优化。【方法】以不同浓度的2,4,4′-TCB与3,3′,4,4′-TCB为唯一碳源,研究苜蓿中华根瘤菌(Sinorhizobium melilon)对不同多氯联苯的降解转化能力,并进行发酵条件优化以及共代谢试验。【结果】接入菌株转化7 d后,随着底物浓度的增加,该菌对2,4,4′-TCB的降解能力呈下降趋势。在最低浓度1.0 mg/L时降解率最高,为93.3%;而在最高浓度50.0 mg/L时为65.1%。对于较难降解的四氯联苯3,3′,4,4′-TCB,菌株在最低浓度1.0 mg/L时降解率为56.2%,最高浓度25.0 mg/L时为22.8%。在温度30°C、pH 7.0、接种量4.5 mL、装液量25 mL时,获得菌株转化10.0 mg/L 2,4,4′-TCB的最优发酵条件,7 d的降解率由原来的54.8%提高到83.6%。柠檬烯、香芹酮及甘露醇作为共代谢底物也可较好地提高菌株降解效果。【结论】苜蓿中华根瘤菌对PCBs有很好的降解效果,研究结果对PCBs的微生物降解及环境中PCBs的生物修复具有较好的意义和应用价值。     

磁铁矿对奥奈达希瓦氏菌MR-1厌氧还原甲基橙性能的影响

【目的】在微生物对染料的厌氧还原转化过程中,前人研究发现磁铁矿可以作为胞外电子传递介质提高或降低染料的微生物还原速率,这两种截然不同的作用结果背后的作用机制仍亟待阐明。【方法】利用水热法合成磁铁矿,选择甲基橙作为微生物胞外还原的典型偶氮染料,研究磁铁矿对奥奈达希瓦氏菌MR-1厌氧还原甲基橙(methyl orange, MO)的影响。【结果】研究发现磁铁矿对MO的降解表现出明显的浓度依赖性效应：同只添加细菌组相比,低浓度组(20-50 mg/L) MO的脱色效率提高了4.07%-10.64%,而高浓度组(100-200 mg/L)下降了3.92%-18.35%。进一步研究发现磁铁矿浓度变化对MO微生物还原的影响与染料在矿物表面的分配无关,主要体现在影响细胞表面形态、代谢活性和电子传递效率等方面。低浓度组ATP生成量提高了1.08%-7.65%,生成了0.033-0.051 mg/L Fe²⁺,而高浓度组ATP生成量降低了38.74%-60.14%,Fe²⁺浓度增至0.091 mg/L。此外,外源Fe²⁺的实验结果证明Fe²⁺对MO的厌氧还原同样表现出低浓度(0.01-0.02 mg/L)促进,高浓度(＞0.05 mg/L)抑制的影响趋势。【结论】低浓度磁铁矿未影响细菌细胞形态,提高了细胞代谢活性,体系中少量的溶解态Fe²⁺有利于MO微生物还原,而高浓度磁铁矿则表现出相反的影响趋势。本研究为全面理解磁铁矿对胞外电子传递的影响及其在有机污染物还原转化中的应用提供了参考。     

球形红细菌厌氧降解2,4-二硝基甲苯（英文）

【目的】研究不同环境条件对2,4-二硝基甲苯(2,4-DNT)生物降解的影响。【方法】采用光合细菌球形红细菌在温度为30°C的光照培养箱中厌氧降解2,4-DNT,并用高效液相色谱仪测定其浓度。【结果】去除2,4-DNT的最佳条件是初始浓度40 mg/L、初始p H 7.0和接种量15%。另外,2,4-DNT在菌体延滞期被细胞吸收,然后在指数期作为碳源被降解。2,4-DNT的去除率在72 h达到98.8%。从液相色谱图中观察到有2种中间代谢产物,但在120 h内产物被逐渐降解。2,4-DNT的去除动力学符合一级速率模型。【结论】不同条件下2,4-DNT的去除率表明球形红细菌能有效降解2,4-DNT。     

三氯乙酸(TCA)提取法与微波提取法检测活性污泥中三磷酸腺苷(ATP)

【目的】针对活性污泥法中的重要参数ATP进行研究分析,通过在不同条件下检测污泥的活性,得出以ATP为指标的污泥活性状态,为准确判定活性污泥的活性提供依据。【方法】分别运用三氯乙酸(TCA)提取法及微波提取法检测活性污泥中的ATP,并对检测ATP的影响因素(TCA浓度、冰浴时间、p H、微波频率及时间等)进行探讨与优化。【结果】运用TCA提取法检测ATP时,在1.0%-7.0%的TCA体积百分数内,活性污泥中TCA最佳体积百分数为2.5%;在2-60 min的冰浴时间内,最佳冰浴时间为10 min;三羟甲基丙烷-乙二胺四乙酸(Tris-EDTA)缓冲液的最佳p H 7.5;运用微波提取法检测ATP适宜的微波辐射条件为:功率800 W,辐射时间15 s。【结论】TCA提取法和微波提取法均可以检测活性污泥中的ATP,但与微波提取法相比,TCA提取法更能保证从细胞内释放出来的ATP的完整性,因此TCA提取法更适合用于检测活性污泥中的ATP。     

Recent advances in the study of Kaposi's sarcoma-associated herpesvirus replication and pathogenesis

It has now been over twenty years since a novel herpesviral genome was identified in Kaposi's sarcoma biopsies. Since then, the cumulative research effort by molecular biologists, virologists, clinicians, and epidemiologists alike has led to the extensive characterization of this tumor virus, Kaposi's sarcoma-associated herpesvirus(KSHV; also known as human herpesvirus 8(HHV-8)), and its associated diseases. Here we review the current knowledge of KSHV biology and pathogenesis, with a particular emphasis on new and exciting advances in the field of epigenetics. We also discuss the development and practicality of various cell culture and animal model systems to study KSHV replication and pathogenesis.     

The structure, reproduction and taxonomy of Vidalia and Osmundaria (Rhodophyta, Rhodomelaceae)

Comprises species occurring mostly in subtidal habitats in tropical, subtropical and warm-temperate areas of the world. An analysis of the type species, V. spiralis (Sonder) Lamouroux ex J. Agardh, a species from Australia, establishes basic characters for distinguishing species in the genus. These characters are (1) branching patterns of thalli, (2) flat blades that may be spiralled on their axis, (3) width of the blade, (4) primary or secondary derivation of sterile and fertile branchlets and (5) position of sterile and fertile branchlets on the thalli. Application of the latter two characters provides an important basic method for separation of species into three major groups. Osmundaria , a genus known only in southern Australia, was studied in relation to Vidalia , and its separation from the Vidalia assemblage is not accepted. Species of Vidalia therefore are transferred to the older genus name, Osmundaria. Two new species, Osmundaria papenfussii and Osmundaria oliveae are described from Natal. Confusion in the usage of the epithet, Vidalia fimbriala Brown ex Turner has been clarified, and Vidalia gregaria Falkenberg, described as an epiphyte on Osmundaria pro/ifera Lamouroux, is revealed to be young branches of the host, Osmundaria prolifera.     

New or rare chromosome counts in Artemisia L. (Asteraceae, Anthemideae) and related genera from Kazakhstan

Fifteen chromosome counts of six Artemisia taxa and one species of each of the genera Brachanthemum, Hippolytia, Kaschgaria, Lepidolopsis and Turaniphytum are reported from Kazakhstan. Three of them are new reports, two are not consistent with previous counts and the remainder are confirmations of very scarce (one to four) earlier records. All the populations studied have the same basic chromosome number, x = 9, with ploidy levels ranging from 2x to 6x. Some correlations between ploidy level, morphological characters and distribution are noted.     

肝癌中HBV和HCV基因和抗原的分布及意义

采用原位分子杂交方法检测HCV RNA及HBV X基因;采用免疫组织化学方法研究HCV核心抗原,非结构区C33c抗原及HBxAg在肝细胞肝癌中的定位及分布.结果表明(1)HCV RNA、HBV X基因在肝细胞肝癌组织检出率分别为40%(55/136)和82%(112/136).HCV RNA定位于癌细胞的胞浆内,阳性细胞呈散在、灶状及弥漫分布三种形式;HBV X基因在肝癌细胞中的分布呈胞浆型、核型及核浆型,阳性细胞也呈上述三种分布形式;(2)HCV C33c抗原、核心抗原在肝细胞肝癌中的阳性率为81%(133/164)及86%(141/164).C33c抗原定位于癌细胞及肝细胞的胞浆内;核心抗原既定位于癌细胞核中,又可定位于胞浆中.C33c抗原阳性细胞以灶状分布为主;而核心抗原阳性细     

Selection with two alleles and complete dominance

For a plant selection model with frequency-independent viabilities, fertilities and selfing rates, it is shown that apart from global fixation, for certain parameter combinations a protected polymorphism and facultative fixation (either allele may become fixed according to initial frequencies) may both occur. Facultative fixation requires different selling rates for the dominant and recessive type. Protection of the polymorphism requires resource allocation for male and female function. In this connection the problem of purely genetically caused population extinction is discussed.
For general frequency dependence and regular segregation, the chances for establishment of a completely recessive gene are compared to those of a completely dominant gene. It is proven that the process of establishment of the recessive gene, despite a fitness advantage, may be considerably endangered by drift effects if random mating prevails. The recessive gene may reach the same effectivity in establishment as a dominant gene, only if the recessive homozygote mates exclusively with its own type during the period of establishment.