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51.
将油桐尺蠖(Buzurasuppressaria)核多角体病毒晚期基因──多角体蛋白基因启动子及5′端编码区,以两种不同方式置于缺乏启动子的氯霉素乙酰基转移酶(CAT)基因上游,使其分别终止在不同翻译终止位点,其宿主菌具有明显不同的氯霉素抗性,最高达200mg/L LB培养基以上,表明昆虫病毒启动子能启动原核基因表达。对多角体蛋白基因启动子能在大肠杆菌中有效工作的原因进行了讨论。 相似文献
52.
Anaerobic Degradation of Propionate by a Mesophilic Acetogenic Bacterium in Coculture and Triculture with Different Methanogens 总被引:4,自引:2,他引:2 下载免费PDF全文
A mesophilic acetogenic bacterium (MPOB) oxidized propionate to acetate and CO2 in cocultures with the formate- and hydrogen-utilizing methanogens Methanospirillum hungatei and Methanobacterium formicicum. Propionate oxidation did not occur in cocultures with two Methanobrevibacter strains, which grew only with hydrogen. Tricultures consisting of MPOB, one of the Methanobrevibacter strains, and organisms which are able to convert formate into H2 plus CO2 (Desulfovibrio strain G11 or the homoacetogenic bacterium EE121) also degraded propionate. The MPOB, in the absence of methanogens, was able to couple propionate conversion to fumarate reduction. This propionate conversion was inhibited by hydrogen and by formate. Formate and hydrogen blocked the energetically unfavorable succinate oxidation to fumarate involved in propionate catabolism. Low formate and hydrogen concentrations are required for the syntrophic degradation of propionate by MPOB. In triculture with Methanospirillum hungatei and the aceticlastic Methanothrix soehngenii, propionate was degraded faster than in biculture with Methanospirillum hungatei, indicating that low acetate concentrations are favorable for propionate oxidation as well. 相似文献
53.
Capsid assembly and involved function analysis of twelve core protein mutants of duck hepatitis B virus. 总被引:6,自引:6,他引:0 下载免费PDF全文
The roles of different regions of the duck hepatitis B virus (DHBV) core protein on viral capsid assembly and related functions were examined. Twelve deletion and insertion mutations which covered 80% of the DHBV C open reading frame were constructed and expressed in Escherichia coli. The N-terminal region (amino acids 3 to 66) of DHBV core protein was important for its tertiary structure and function in E. coli. The expressed core mutants without this region apparently inhibited E. coli growth. The results of transmission electron microscopy of E. coli thin sections, capsid agarose gel, and sucrose gradient sedimentation demonstrated that a few DHBV core mutants with insertion in the N terminus and deletion in the C terminus retained the ability to form core-like particles in E. coli. However, other mutations in most of N-terminal and central regions strongly inhibited the self-assembly ability of DHBV core protein in E. coli. In addition, the mutant with a C-terminal region deletion (amino acids 181 to 228) lost most of the nucleic acid-binding activity of the DHBV core protein. 相似文献
54.
Chang-Zhi Dong Jean-Luc Montillet Christian Triantaphylidès 《Physiologia plantarum》1994,90(2):307-312
The effects of ionizing radiation, used in post-harvest treatment of fruit and vegetables. were investigated on cultured apple cells ( Pyrus malus L. cv. Royal Red) on a short-term period. Irradiation (2 kGy) induced an increase of passive ion effluxes from cells and a decrease of cell capacity to regulate external pH. These alterations are likely due to effects on plasma membrane structure and function and were further investigated by studying the effects of irradiation on plasma membrane H+ -ATPase activity. Plasma membrane-enriched vesicles were prepared and the H+ -ATPase activity was characterized. Irradiation of the vesicles induced a dose dependent inhibition of H+ -ATPase activity. The loss of enzyme activity was immediate, even at low doses (0.5 kGy), and was not reversed by the addition of 2m M dithiothreitol. This inhibition may be the result of an irreversible oxidation of enzyme sulfhydryl moieties and/or the result of changes induced within the lipid bilayer affecting the membrane-enzyme interactions. Further analysis of the H+ -ATPase activity was carried out on vesicles obtained from irradiated cells confirming the previous results. In vivo recovery of activity was not observed within 5 h following the treatment, thus explaining the decrease of cell capacity to regulate external pH.
This rapid irreversible inhibition of the plasma membrane H+ -ATPase must be considered as one of the most important primary biochemical events occurring in irradiated plant material. 相似文献
This rapid irreversible inhibition of the plasma membrane H
55.
植物细胞离析酶的制备和应用 总被引:2,自引:0,他引:2
用 Aspergillus sp.A-19菌经固体发酵研制成一种新的植物细胞离析酶(SeparatasezA—P)。其离析单细胞的酶活力平均为70 767u/g,有效作用的pH在3.0—7.0,温度为20—45℃。发酵培养基配方是麸皮:桔皮粉:(NH4)2SO4(w/w)为100:100:O.63,料水比为1 :2.0,培养适宜条件为25℃、60小时。 相似文献
56.
红毛五加叶的三萜皂甙 总被引:2,自引:0,他引:2
红毛五加(AcanthopanaxgiraldiiHarms)系五加科五加属植物,分布于河北、河南、四川、陕西、甘肃等省,有祛风湿、通关节、强筋骨、治痿痹等功效[1]。其化学成分未见报道。本文报道红毛五加叶的5个三萜皂甙(甙Ⅰ、Ⅱ、Ⅲ、Ⅳ和Ⅴ)的分离鉴定。它们均首次从该属植物发现,其结构如下: R1 R2 Ⅰ rham-(1→2)-ara H Ⅱ H rham-(1→4)-glc-(1→6)-glc … 相似文献
57.
河西走廊不同生态型芦苇核酸代谢季节动态研究 总被引:4,自引:0,他引:4
分布在甘肃河西走廊的4 种生态型芦苇(Phragm itescom m unisTrin.)的核酸代谢季节变化有差异。盐化草甸芦苇RNA 含量持续增加,DNA 含量相对稳定,其它3 种生态型芦苇的RNA 和DNA 含量以5月份为最高。过渡带芦苇的RNA 含量、沼泽芦苇及沙丘芦苇的DNA含量9 月份略有增高。盐化草甸芦苇与过渡带芦苇的DNase和RNase的活性7 月份最高,沼泽芦苇与沙丘芦苇的DNase和RNase活性5—9 月份呈增高趋势。盐化草甸芦苇的DNA 和RNA 合成活性不断升高,过渡带芦苇和沼泽芦苇的DNA 和RNA 合成活性及沙丘芦苇的RNA 合成活性5—9月份均降低,仅沙丘芦苇的DNA合成活性增强。RNA 聚丙烯酰胺梯度凝胶电泳分析结果表明,4 种生态型芦苇均含有25S、23S、18S、16S大分子量rRNA 和小分子量5.8S、5S、4.5SrRNA 及4StRNA。大分子量RNA 的含量高于小分子量RNA 含量。不同生态型及同一生态型芦苇的不同发育时期,相同的RNA 组分含量各不相同。且发育过程中23S、18S、16SrRNA 在不同月份发生不同程度的降解。由此,我们认为,核酸代谢的差异性是4 种生态型由生长转入衰 相似文献
58.
三褶脉紫菀中的新二萜甙 总被引:1,自引:0,他引:1
三褶脉紫菀(AsterageratoidesTurcz.)系菊科多年生草本植物,遍布全国,是民间常用的中药,有清热解毒、祛痰镇咳的功效[1,2]。化学工作者们曾从其同属植物紫菀(AstertararicusL.f.)中分离到紫菀酮(shionone)、槲皮素(quercetin)、无羁萜(friedelin)、表无羁萜(epifriedelinel)、毛叶醇(lachnophyllol)、乙酸毛叶酯(lachnophyllolacetate)、茴香醚(anethole)以及紫菀三萜皂甙[2—4]… 相似文献
59.
60.
L. H. Li Y. S. Dong 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1993,87(3):361-368
Trigeneric hybrids between the (Triticum aestivum ×Agropyron michnoi) F1 (CM, 2n=5x=35; ABDPP) and two winter rye (Secale cereale L., 2n=2x=14; RR) cultivars, Wugong 774 and AR-132, were synthesized. Such trigeneric hybrids could be used to transfer resistance genes for powdery mildew from rye to CM and subsequently to common wheat and to identify (1) the effects of the P genome ofAgropyron on the self-fertility of the hybrids and (2) the differences in genetic background between rye cultivars with marked differences in pollinating habit. The trigeneric hybrids varied widely in morphology and showed a high level of resistance to such diseases as barley yellow dwarf virus (BYDV), stripe rust, leaf rust, stem rust, and powdery mildew. Selfed and many backcross derivatives were obtained from the trigeneric hybrids. The results indicated that rye cvs Wugong 774 and AR132 arose from different gene pools and that the P genome ofAgropyron carries gene(s) responsible for chromosome segregation, leading to functional gamete formation and self-fertility of the hybrids. The F2 and BC1 plants could be obtained in two ways — fusion of the unreduced gametes and the assumed apomixis of unreduced female gametes in the trigeneric hybrid plant II-4 — which indicates that this trigeneric hybrid may be a special genetic stock. Chromosome pairing in the trigeneric hybrids and ways of producing wheat/rye and wheat/Agropyron translocations are discussed. 相似文献