子囊霉素产生菌吸水链霉菌FIM260840基因转移系统的建立

目的:建立子囊霉素产生菌吸水链霉菌FIM260840的接合基因转移体系,以便基因敲除和外源基因表达等遗传操作。方法:以整合型质粒p SET152为出发质粒,通过接合转移构建并子囊霉素产生菌FIM260840的基因转移系统。结果:12.5μg/m L安普霉素可有效筛选接合子。经PCR验证,质粒成功整合到菌株FIM260840基因组DNA中,所获接合子的安普霉素抗性高达400μg/m L以上。接合子经多次传代后,导入的质粒p SET152仍稳定整合于接合子基因组DNA上。结论:建立了高效、简便的吸水链霉菌FIM260840的基因转移系统,为该菌的生物合成基因改造奠定了基础。     

一种基于温敏质粒的新型基因敲除方法

基于温敏型质粒而不用线性DNA的方法用于快速敲除沙门氏菌染色体上的目的基因。以伤寒沙门氏菌S.ty2基因组为模板扩增得到的ssaV基因的上下游同源臂,与两端带有FRT位点的卡那霉素抗性基因片段连接到温敏型质粒pHY304,共同构建同源重组载体;然后转化S.ty2,通过筛选得到带有抗性标记的重组菌。通过转入重组酶表达质粒pCP20,去除抗性标记,得到ssaV基因缺失的重组菌,并在 DNA 水平进行了鉴定。建立了一种改进的基于温敏质粒的沙门氏菌的基因敲除方法,此方法也值得在其他革兰氏阴性菌的基因敲除中尝试应用。     

庆大霉素生物合成基因genN的研究

利用生物信息学方法分析庆大霉素生物合成特色基因gen N的功能,构建gen N缺失的基因工程菌。首先运用分子生物学技术构建同源重组质粒p FU604,其次重组质粒经接合转移导入绛红色小单孢菌M.purpurea GK1101。最后,基于同源重组机制,利用安普霉素抗性筛选及PCR鉴定,得到gen N基因缺失的工程菌(M.purpurea GKN-27)。结果显示:较岀发菌GK1101,基因工程菌GKN-27不再继续合成庆大霉素C1a和C2b,阻断庆大霉素生物合成代谢流,并积累分子量为497、524、523、503四种新的中间代谢物,新的中间代谢物将有望开发新型药物。同时,也表明gen N不是C-6'N甲基化酶编码基因。     

庆大霉素生物合成基因genA的功能

【目的】在绛红色小单孢菌G1008(Micromonospora purpurea G1008)上构建genA基因缺失工程菌,通过分析其次级代谢产物的变化,推测genA基因功能。【方法】构建用于gen A基因框内敲除的质粒pAB103,经接合转移导入绛红色小单孢菌G1008,安普抗性及PCR扩增筛选获得genA缺失工程菌GA1048。【结果】与出发菌G1008相比,工程菌GA1048不再合成庆大霉素C族组分,主要积累中间代谢产物庆大霉素A2。【结论】genA基因失活导致庆大霉素生物合成代谢流中断,暗示gen A基因参与加洛糖胺C-3″位的氨甲基化。     

Pseudomonas plecoglossicida NyZ12基因无痕敲除方法的建立

旨在建立一种适合环己胺降解菌NyZ12基因无痕敲除的可靠方法。通过overlapping PCR技术将目的基因上下游同源臂融合并克隆到自杀载体pEX18km上,将重组质粒转化到大肠杆菌S17pir中,再通过接合转移到假单胞菌NyZ12菌株内,经pEX18km质粒上sacB基因的反向筛选得到突变株并通过PCR方法和测序鉴定。结果显示,成功构建了假单胞菌NyZ12菌株orf4637的基因突变株(NyZ12Δ4637)。通过自杀载体同源重组可以成功获得敲除的无痕突变株,且突变株基因组上没有任何抗性筛选标记残留,为环己胺降解菌NyZ12基因功能研究提供了可靠的基因敲除技术。     

依尼奥小单孢菌抗性基因sisR的克隆研究

从产西索米星的依尼奥小单孢菌中克隆高抗性新基因sisR,借助计算机设计PCR引物,从西索米星的产生菌依尼奥小单孢菌的染色体DNA中,经PCR扩增获得DNA序列长度不等的DNA片段。将这些DNA片段克隆至pUC19载体质粒并导入大肠杆菌,从中筛选到5个抗西索米星的转化子(其中一个命名为sisR)显示对西索米星的高抗性(超过1000μg/mL)。经DNA测序并通过互联网Biast比对,确认对该抗性负责的DNA片段是一个未见报道的新基因。     

预防仔猪腹泻无抗性基因工程菌株的构建

以原来含热不稳定肠毒素B亚单位基因质粒DNA为载体,插入lacZ基因,构建了一个既能表达LT-B亚单位又能表达B-半乳糖苷酶的含四环索抗性基因的重组体。在该重组DNA的四环素抗性基因内再插入K 88粘附因子抗原基因,从而灭活了四环素抗性基因。经测定该重组体能表达LT－B和K88两种抗原,lacZ基因取代四环素抗性基因,成为良好筛选标记。所构建的重组质粒能稳定存在。     

抑制性消减杂交法筛选炭样小单孢菌JXNU-1中抗生素合成相关基因

为了筛选炭样小单孢菌JXNU-1中抗生素合成相关基因,本研究以培养36 h(抗生素分泌前)的炭样小单孢菌JXNU-1菌体所合成c DNA为Driver,以培养108 h(抗生素分泌后)的菌体所合成的c DNA为Tester,构建炭样小单孢菌JXNU-1分泌抗生素前后的差异c DNA消减文库,筛选差异表达基因,荧光定量PCR验证其表达量,生物信息学方法分析其功能。研究结果表明,经抑制性消减杂交筛选得到5个与抗生素合成相关的差异表达基因;比照炭样小单孢菌JXNU-1全基因组序列,将所获5个基因定位到4个生物合成基因簇中,最后确定了炭样小单孢菌JXNU-1中抗生素生物合成相关的基因簇。本研究为阐明炭样小单孢菌JXNU-1中抗生素的生物合成机制提供了实验依据。     

依尼奥小单孢菌抗性基因sisR的克隆研究

从产西索米星的依尼奥小单孢菌中克隆高抗性新基因sisR ,借助计算机设计PCR引物 ,从西索米星的产生菌依尼奥小单孢菌的染色体DNA中 ,经PCR扩增获得DNA序列长度不等的DNA片段。将这些DNA片段克隆至pUC19载体质粒并导入大肠杆菌 ,从中筛选到 5个抗西索米星的转化子 (其中一个命名为sisR)显示对西索米星的高抗性 (超过 10 0 0 μg mL)。经DNA测序并通过互联网Blast比对 ,确认对该抗性负责的DNA片段是一个未见报道的新基因。     

大肠杆菌-链霉菌高效接合载体的构建及其应用

以链霉菌质粒SCP2 的衍生质粒pHJL400为基础 ,构建了能够在大肠杆菌到链霉菌之间进行高效接合转移的质粒pGH112。pGH112含有在大肠杆菌和链霉菌中复制起始位点 ,以及分别在大肠杆菌和链霉菌中进行筛选的抗性标记。用pGH112转化EscherichiacoliET12567(pUZ8002 )后 ,与天蓝链霉菌 (StreptomycescoelicolorA3(2 ) )、除虫链霉菌 (Streptomycesavermitilis)、变铅青链霉菌 (StreptomyceslividansTK54 )、毒三素链霉菌 (StreptomycestoxytriciniNRRL15443)、委内瑞拉链霉菌 (Streptomyces.venezuelaeISP5230 )和红色糖多孢菌 (Saccharopolyporaerythraea)进行接合 ,发现本文构建的pGH112与pKC1139相比 ,接合转移效率较高 ,稳定性好 ,而且宿主范围较广。把组成型启动子ermE 与绿色荧光蛋白基因 (gfp)克隆到本文构建的pGH112 ,通过接合转移到链霉菌中 ,gfp获得表达,证明其可以用作基因接合转移的有效工具载体,这为研究链霉菌的基因功能创造了有利条件上。     

Investigation of the mechanism of temperature sensitivity of the electroreceptors of ampullae of lorenzini

In experiments on Black Sea skates (Raja clavata), the potential of the receptor epithelium of the ampullae of Lorenzini and spike activity of single nerve fibers connected to them were investigated during electrical and temperature stimulation. Usually the potential within the canal was between 0 and –2 mV, and the input resistance of the ampulla 250–400 k. Heating of the region of the receptor epithelium was accompanied by a negative wave of potential, an increase in input resistance, and inhibition of spike activity. With worsening of the animal's condition the transepithelial potential became positive (up to +10 mV) but the input resistance of the ampulla during stimulation with a positive current was nonlinear in some cases: a regenerative spike of positive polarity appeared in the channel. During heating, the spike response was sometimes reversed in sign. It is suggested that fluctuations of the transepithelial potential and spike responses to temperature stimulation reflect changes in the potential difference on the basal membrane of the receptor cells, which is described by a relationship of the Nernst's or Goldman's equation type.I. P. Pavlov Institute of Physiology, Academy of Sciences of the USSR, Leningrad. I. M. Sechenov, Institute of Evolutionary Physiology and Biochemistry, Academy of Sciences of the USSR, Leningrad. Pacific Institute of Oceanology, Far Eastern Scientific Center, Academy of Sciences of the USSR, Vladivostok. Translated from Neirofiziologiya, Vol. 12, No. 1, pp. 67–74, January–February, 1980.     

Principles of organization and evolution of systems of regulation of functions

Evolution of living organisms is closely connected with evolution of structure of the system of regulations and its mechanisms. The functional ground of regulations is chemical signalization. As early as in unicellular organisms there is a set of signal mechanisms providing their life activity and orientation in space and time. Subsequent evolution of ways of chemical signalization followed the way of development of delivery pathways of chemical signal and development of mechanisms of its regulation. The mechanism of chemical regulation of the signal interaction is discussed by the example of the specialized system of transduction of signal from neuron to neuron, of effect of hormone on the epithelial cell and modulation of this effect. These mechanisms are considered as the most important ways of the fine and precise adaptation of chemical signalization underlying functioning of physiological systems and organs of the living organism