产肌醇酿酒酵母基因工程菌的构建

【目的】过表达酿酒酵母肌醇合成关键酶基因INO1,促进肌醇合成,构建能够分泌肌醇的基因工程菌株。【方法】构建r DNA介导的INO1基因多拷贝整合表达载体p URIH,电转化酿酒酵母Y01菌株,构建工程菌株YI2-1和YI2-2,荧光定量PCR方法分析INO1基因表达量。敲除Kan MX抗性基因,HPLC检测重组菌发酵液中肌醇含量。【结果】获得INO1基因过表达菌株YI2-1和YI2-2,YI2-1的INO1基因表达量是出发菌Y01的16.235倍。敲除Kan MX抗性基因的菌株命名为YI2-1△KP,初步检测YI2-1△KP产肌醇量为627 mg/L。【结论】r DNA介导的INO1基因多拷贝整合表达载体p URIH能够有效地过表达目的基因;过表达菌株合成的肌醇不仅能满足自身的需要,而且能够向胞外分泌,具有潜在的工业应用价值。     

近海柴油降解菌群的构建及其对柴油的降解特性

【目的】实施近海柴油污染的生物治理。【方法】以柴油为唯一碳源,从深圳港口海域富集筛选柴油降解菌;采用复配、正交试验等方式构建混合菌群;通过单因素试验研究环境因素对菌群降解柴油的影响;使用气相色谱-氢火焰检测器(GC-FID)分析降解前后柴油各组分的变化;通过生理生化试验和16S rRNA基因序列分析对菌株进行鉴定。【结果】获得了16株柴油降解菌,7 d内对柴油的降解率最高达40.8%;选择菌株C1-8、C2-10、C3-13构建了混合菌群CQ1,投加量分别为0.5%、2.0%和1.0%,CQ1对柴油去除率比单菌提高了10%以上;CQ1的最适环境条件为：温度30 °C、pH 7.6、摇床转速220 r/min、柴油浓度20 g/L,优化后9 d内对柴油去除率达60%以上;GC-FID结果显示,菌群CQ1可降解大部分C11?C27的正构烷烃,对C21?C27的烷烃降解可达100%。经鉴定,菌株C1-8、C2-10和C3-13分别为微杆菌(Microbacterium sp.)、剑菌(Ensifer sp.)和变异棒杆菌(Corynebacterium variabile)。【结论】CQ1在近海柴油污染的生物修复中具有良好的应用前景。     

一株林可霉素降解菌的筛选鉴定及其降解机制

【背景】抗生素污染越来越引起人们的关注。利用微生物处理抗生素污染被认为是一种环境友好型的方法。【目的】筛选林可霉素高效降解菌并研究其降解机制。【方法】经形态学观察、生理生化鉴定和16S rRNA基因测序分析进行鉴定;通过PCR技术和质谱分析技术对该菌抗性基因和降解产物等进行分析。【结果】从林可霉素菌渣堆肥样本中获得一株高效降解林可霉素的假单胞菌(Pseudomonas RST-1),该菌在林可霉素浓度为3.0 g/L的牛肉膏蛋白胨培养基上培养40 h后,林可霉素降解率高达57.3%。该菌含有intI1、sul1、sul2等抗性基因,降解产物为去甲基林可霉素和2-丙基-N-甲基脯氨酸。【结论】菌株RST-1具有高效降解林可霉素的能力,推测可能的降解机制为去甲基化和酰胺键水解作用,该菌株降解特性及降解机制研究为林可霉素降解工程菌及其高效降解菌剂的研制奠定了基础。     

一株降解纤维素放线菌的产纤维素酶基因克隆与表达

【背景】纤维素在自然界中储量丰富,但天然纤维素的难降解性成为广泛应用纤维素资源的壁垒,近年来利用微生物来降解纤维素成为热点研究。【目的】筛选分离得到一株具有降解纤维素功能的放线菌菌株Lb1,通过全基因组测序确定其产纤维素酶关键基因5676,对基因5676进行克隆转化,使其在大肠杆菌中进行表达。【方法】通过基因工程技术将产纤维素基因连接到表达质粒上并导入表达菌株,对其降解纤维素生成葡萄糖的能力进行探究。【结果】将Lb1菌株的16S rRNA基因进行比对,确定菌株Lb1属于链霉菌属,命名为Streptomyces sp. Lb1。成功构建出纤维素酶表达载体,并且导入表达菌株大肠杆菌BL21(DE3),重组菌株的产纤维素酶能力大于空载菌株。【结论】通过基因工程技术成功克隆出产纤维素酶基因,从而表达纤维素酶,为今后利用微生物降解纤维素的大规模应用提供参考。     

大肠杆菌Zn2+敏感突变株构建及其功能验证

【背景】Zn²⁺在细胞解毒及许多生理过程中发挥着关键作用,Zn²⁺转运蛋白已逐渐引起人们的重视。在大肠杆菌中,zntA和zitB是2个外排Zn²⁺的关键基因。【目的】构建大肠杆菌Zn²⁺敏感突变株,并对其功能进行验证。【方法】以Escherichia coli DH5α为出发菌株,利用λ Red重组系统,通过携带卡那霉素抗性基因的同源重组片段敲除zntA基因。在单基因敲除菌株基础上,利用携带庆大霉素抗性基因的同源重组片段敲除zitB基因,获得一株敲除了zntA和zitB的双基因敲除菌株KZAB04。通过功能互补实验检测基因敲除菌株及对照菌株对不同浓度Zn²⁺的敏感程度。【结果】基因敲除菌株KZAB04比出发菌株E. coli DH5α具有更高的Zn²⁺敏感性。【结论】大肠杆菌Zn²⁺敏感突变株构建成功。该菌株的构建为zntA和zitB基因功能的研究提供了必要条件,同时也为其他Zn²⁺转运蛋白基因的功能鉴定与分析奠...     

一株对羟基苯甲酸酯海洋降解菌的关键酶基因克隆与表达

【背景】对羟基苯甲酸及其酯类常作为合成多种芳香族化合物的前体物质广泛应用于多个领域,但其难以自然降解给环境造成了污染问题,同时这些污染物随着洋流迁移到海洋中破坏海洋生态环境。【目的】从海洋环境中筛选对羟基苯甲酸酯高效降解菌,通过全基因组测序及注释分析,预测对羟基苯甲酸酯代谢通路,确定其代谢过程中的关键酶并进行功能研究。【方法】通过富集培养从海洋环境中分离对羟基苯甲酸酯降解菌,利用基因克隆技术将降解对羟基苯甲酸酯关键酶基因在大肠杆菌中高效表达,探究重组蛋白活性及酶学特征。【结果】从海底泥沙中筛选到一个菌株,经16S rRNA基因测序鉴定为硝化柠檬球菌(Citricoccus nitrophenolicus);该菌株能够利用多种对羟基苯甲酸酯类物质进行生长,在甲酯为碳源条件下生长状态最好;将羧酸酯酶基因和单加氧酶基因在大肠杆菌中进行高效表达,重组表达的羧酸酯酶最适反应条件为：pH 8.0,30℃反应30 min;重组表达的单加氧酶活性表达依赖于辅酶,Mg²⁺、Mn²⁺、Zn²⁺和Fe3+可增强该酶活性;经荧光定量PCR进一步...     

苯酚降解工程菌Bacillus subtilis dqly-2的构建

目的:构建苯酚降解工程菌Bacillus Subtilis dqly-2.方法:选取2株苯酚降解菌,分别为铜绿假单胞菌Pseudomonas aeruginosa zllf4和枯草芽孢杆菌Bacillus Subtilis BHf3-4,体外扩增Pseudomonas aeruginosa zllf4的邻苯二酚2,3双加氧酶基因(SYJ),并将此基因转入Bacillus Subtilis BHf3-4中,构建基因工程菌,并对野生菌和工程菌降解能力进行比较.结果:作用96h后,工程菌苯酚降解率为96.18％,显著高于野生菌的84.78％.结论:成功构建高效苯酚降解基因工程菌.     

血红蛋白基因在脱硫菌R-8中的表达及其在柴油脱硫中的应用

摘要：【目的】旨在构建一株优良的工程菌株,对血红蛋白基因在柴油的生物脱硫领域的应用做初步的探索。【方法】以德氏假单胞菌（Pseudomonas delafieldii） R-8为出发菌株,通过基因工程的手段,构建透明颤菌（Vitreoscilla）血红蛋白基因表达质粒并电击导入原始菌株,得到重组菌P. delafieldii R-8-2。【结果】R-8-2菌株的CO差光谱在419 nm处有特征峰出现,表明血红蛋白在脱硫菌中得到了有效表达。R-8-2菌株和R-8菌株相比,生长得到改善,相同培养条件下菌体密度比R-8提高了20%,最大脱硫活性能够达到R-8的2.4倍。在实际柴油脱硫实验中,R-8-2菌株能将柴油的硫含量降至96.6 mg/L,脱硫率达到69.9%,而R-8仅为57.2%。【结论】R-8-2是在较低溶氧条件下仍能保持较高的菌体密度和脱硫活性的基因工程菌株,具有良好的应用前景,该研究为血红蛋白基因在生物脱硫工业的应用提供参考。     

转解毒酶基因工程菌的构建及酶活性分析

实验构建了能高效降解有机磷、有机氯等四大类农药的转解毒酶基因工程菌。将抗性库蚊解毒酶酯酶B1基因片段引入融合表达载体pThioHisA中,转化入大肠杆菌DH5α,在IPTG诱导下,经过8 h,酯酶B1在大肠杆菌中的获得融合高效表达。研究了工程菌的酶酯活性,重组质粒pThioHisA-B1表达的酯酶融合蛋白具有较高的酯酶B1活性,能高效降解酯酶的特异性底物α-乙酸萘酯(-αNA)和β-乙酸萘酯(-βNA),该工程菌将为农药污染的生物治理提供新手段。     

一株深海热液环境来源的PAHs降解菌TVG9-Ⅶ的系统发育与降解基因

【目的】对一株深海热液环境来源的多环芳烃(PAHs)降解菌进行系统发育分析并对其降解特性和降解机制进行研究。【方法】对16S rRNA基因进行扩增和测序,进行基于16S rRNA基因序列的系统发育分析;利用GC-MS测定其对PAHs的降解率;通过构建基因组Fosmid文库,克隆PAHs降解基因簇;并利用RT-PCR和qPCR研究关键降解酶基因在不同PAHs诱导下的表达情况。【结果】从西南太平洋劳盆地热液沉积物中分离到一株PAHs降解菌株TVG9-Ⅶ,系统发育分析结果表明,该菌株属于新鞘氨醇杆菌属(Novosphingobium),与该属的Novosphingobium indicum H25T系统发育关系最为密切,它们的16S rRNA基因序列相似性高达99.7%。该菌株在21 d内对菲、荧蒽和芘的降解率分别为95.2%,57.3%和69.6%。从Fosmid文库中筛选得到一个负责PAHs降解的上游基因簇,包含了PAHs起始降解双加氧酶大小亚基(pheA1a/b)基因和一个脱氢酶基因;RT-PCR和qPCR实验表明,双加氧酶大亚基基因pheA1a在菲的诱导下上调表达4.2倍,而在萘及高环荧蒽和芘的诱导下无上调。【结论】菌株TVG9-Ⅶ是Novosphingobium属深海热液来源的PAHs降解菌,具有良好的降解特性,特别是对高环PAHs的降解效果较好。     

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.