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The BGL1 gene, encoding β-glucosidase in Saccharomycopsis fibuligera, was intracellular, secreted or cell-wall associated expressed in an industrial strain of Saccharomyces cerevisiae. The obtained recombinant strains were studied under aerobic and anaerobic conditions. The results indicated that both the wild type and recombinant strain expressing intracellular β-glucosidase cannot grow in medium using cellobiose as sole carbon source. As for the recombinant EB1 expressing secreted enzyme and WB1 expressing cell-wall associated enzyme, the maximum specific growth rates (μmax) could reach 0.03 and 0.05 h−1 under anaerobic conditions, respectively. Meanwhile, the surface-engineered S. cerevisiae utilized 5.2 g cellobiose L−1 and produced 2.3 g ethanol L−1 in 48 h, while S. cerevisiae secreting β-glucosidase into culture broth used 3.6 g cellobiose L−1 and produced 1.5 g ethanol L−1 over the same period, but no-full depletion of cellobiose were observed for both the used recombinant strains. The results suggest that S. cerevisiae used in industrial ethanol production is deficient in cellobiose transporter. However, when β-glucoside permease and β-glucosidase were co-expressed in this strain, it could uptake cellobiose and showed higher growth rate (0.11 h−1) on cellobiose. 相似文献
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植物离体培养细胞的类减数分裂 总被引:1,自引:0,他引:1
PlantSomaticMeiosis-likeDivisioninvitroChenYihuaChenZhenghua(InstituteofGeneties,TheChineseAcademyofSeienees,Beijing100101)在离休培养条件下,相物细胞染色作容易发生数目和结构变异,这些变计包括染色体信性变异、非整倍体的出现、染色体断裂、易位、缺失、落后染色体及染色体桥等[1,3—5,6—8,13,14,21,22,26,28,30),这此变异是体细胞无性系变异(somaclonalvariation)的来源之一.在众多的报道中,有一种染色体数目减少的现象被人们所注意。过去减数分裂总是与雌雄配子发生过程相连系的、在离休诱导细胞脱分… 相似文献
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Xylan is the second most abundant polysaccharide in dicot wood, and thus elucidation of the xylan biosynthetic pathway is required to understand the mechanisms controlling wood formation. Genetic and chemical studies in Arabidopsis have implicated three genes, FRAGILE FIBER8 (FRA8), IRREGULAR XYLEM8 (IRX8) and IRREGULAR XYLEM9 (IRX9), in the biosynthesis of glucuronoxylan (GX), but the biochemical functions of the encoded proteins are not known. In this study, we determined the effect of the fra8, irx8 and irx9 mutations on the activities of xylan xylosyltransferase (XylT) and glucuronyltransferase (GlcAT). We show that microsomes isolated from the stems of wild-type Arabidopsis exhibit XylT and GlcAT activities in the presence of exogenous 1,4-linked beta-d-xylooligomers. Xylooligomers ranging in size from two to six can be used as acceptors by XylT to form xylooligosaccharides with up to 12 xylosyl residues. We provide evidence that the irx9 mutation results in a substantial reduction in XylT activity but has no discernible effect on GlcAT activity. In contrast, neither XylT nor GlcAT activity is affected by fra8 and irx8 mutations. Our results provide biochemical evidence that the irx9 mutation results in a deficiency in xylan XylT activity, thus leading to a defect in the elongation of the xylan backbone. 相似文献
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Glass needles were successfully used to dissect the soybean (Glycine max L. ) single chromosome under the micromanipulator in this research. Two dissected soybean chromosomes were digested by Sau3A in two 0.5 mL Eppendorf tubes respectively. The two ends of chromosomal fragments were ligated with Sau3A linker adoptor. After two rounds of PCR amplification, smear DNA fragments ranged from 0.3 to 3 kb were acquired. Southern hybridization result showed the PCR products from the two single soybean chromosomes were homogeneous with the soybean genomic DNA, indicating that DNAs from the two single chromosomes have been successfully amplified. At the same time, the amplified products from the two of the distinguished single chromosome appeared somewhat different. The authors dissected the small chromosomes only by a traditional inverted microscope. Therefore, this research provides a plausible chance for amplification and microcloning of single small chromosomes. 相似文献
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基因调控网络表现的是大量基因受到转录因子的调控而最终转录翻译为蛋白质进而实现生物功能的复杂信息, 是人们理解生物过程和基因功能的重要内容。为了理解基因调控网络中的调控机理, 网络的拓扑结构及其组织方式是极其重要的研究内容之一。它不仅能说明网络的局部特征, 并且能揭示调控网络的构造方法, 同时还能对调控信号通路进行全面系统的分析。调控网络可分为4层结构: 调控元件、Motif、模块和整个网络。当前, 这种层次结构受到人们越来越多的认可。文中重点讨论motif和模块两层, 比较分析了近年来对网络组织结构的多方面研究内容, 阐述了各个研究结果与结论具有的生物学意义, 并指出了其中存在的问题。在此基础上, 文中还针对这些问题提出了可能存在的研究方向, 并展望了基因调控网络模块化组织的研究前景。 相似文献
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为分析外源精子对人工诱导雌核发育草鱼基因组的影响,用随机扩增多态性和微卫星技术对经两代连续人工诱导,遗传背景一致的雌核发育草鱼以及母本草鱼和父本鲤鱼的基因组DNA进行了比较分析。10个随机引物在雌核发育草鱼中共检测到104个RAPD位点,在鲤鱼中检测到103个位点。7对微卫星引物在雌核发育草鱼中共扩增出4个微卫星位点,在鲤鱼中检测到22个位点。两种方法在雌核发育草鱼和鲤鱼中所检测到的位点均没有一个相同。根据RAPD和微卫星分析数据进行的遗传相似度分析表明二代人工雌核发育草鱼群体与其一代人工诱导雌核发育草鱼母本的遗传相似度从0.9903到1.000,与父本鲤鱼的遗传相似度为0.000。这些实验结果证明在适当的紫外线处理强度下,鲤鱼精子的遗传物质能够被完全破坏,不会对雌核发育草鱼的基因组造成遗传污染。 相似文献