CO2激光辐照对酿酒酵母菌的诱变作用

应用红外ＣＯ２激光对甘蔗糖蜜工业性生产用酿酒酵母菌Ｓａｃｃｈａｒｏｍｙｃｅｓ ｃｅｒｅｖｉｓｉａｅ ＡＳ２．１１８９进行辐照处理,经酵母菌糖蜜酒精发酵试验,发现红外ＣＯ２激光对酿酒酵母菌具有诱变作用,并初步筛选到决乙醇含量有较大变化的辐照变异菌株;同时,通过对这些辐照变异菌株的乙醇脱氢酶同工酶的比较分析,进一步证实了红外ＣＯ２激光对酿酒酵母酶的诱变作用。从而为工业上利用红外ＣＯ２激光对酿酒酵母菌进     

CO2激光辐照对酿酒酵母菌的诱变作用*

应用红外ＣＯ_２激光对甘蔗糖蜜工业性生产用酿酒酵母菌Ｓａｃｃｈａｒｏｍｙｃｅｓ ｃｅｒｅｖｉｓｉａｅ ＡＳ２．１１８９进行辐照处理,经酵母菌糖蜜酒精发酵试验,发现红外ＣＯ_２激光对酿酒酵母菌具有诱变作用,并初步筛选到产乙醇含量有较大变化的辐照变异菌株;同时,通过对这些辐照变异菌株的乙醇脱氢酶同工酶的比较分析,进一步证实了红外ＣＯ_２、激光对酿酒酵母菌的诱变作用．从而为工业上利用红外ＣＯ_２激光对酿酒酵母菌进行诱变     

He-Ne激光辐照酿酒酵母菌的诱变效应

本文应用ＨｅＮｅ激光对甘蔗糖蜜工业性生产用酿酒酵母菌ＳａｃｃｈａｒｏｍｙｃｅｓｃｅｒｅｖｉｓｉａｅＡＳ２．１１８９进行辐照处理,经酵母菌糖蜜酒精发酵试验,对产乙醇含量进行了气相色谱分析,发现ＨｅＮｅ激光对酿酒酵母菌具有明显的生物刺激效应和可能的诱变作用,并初步筛选到产乙醇含量有较大变化的辐照变异菌株;同时,通过对这些辐照变异菌株的乙醇脱氢酶同工酶的分析,进一步证实了ＨｅＮｅ激光对酿酒酵母菌的诱变作用。这就为工业上利用Ｈｅ－Ｎｅ激光对酿酒酵母菌进行诱变育种展现新的前景。     

激光诱变微生物的遗传和刺激效应机理及育种研究 Ⅰ.CO_2激光对酒精酵母菌的诱变效应

本文选择甘蔗糖蜜酒精工业性生产用酿酒酵母菌SaccharomycescerevisiaeAS2.1189作为出发菌株,利用CO2激光对其进行辐照处理．制定出该菌最佳致死量的基础上,从A、B……E等5个不同照射剂量中,共挑取辐照菌639株．经糖蜜发酵后,对产乙醇含量进行了气相色谱分析．结果筛选出乙醇含量高于出发菌株5％～11％范围的辐照菌有5株;而低于10％～33％之间的为9株．表明CO2激光对该酵母菌产乙醇含量的高低有刺激效应．亦提示了CO2激光对酵母菌乙醇脱氢酶系的激活有刺激作用．     

清酒酵母与酿酒醇母原生质体融合的研究

清酒酵母（ＳａｃｃｈａｒｏｍｙｃｅｓｓａｋｅＹａｂｅ）是日本清酒的生产菌株．耐酒精能力强;Ｋ氏酿酒酵母（ＳａｃｃｈａｒｏｍｙｃｅｓｃｅｒｅｖｉｓｉａｅＫ）是酒精生产的常用菌株,发酵力强。本文应用原生质体融合技术进行了二菌株原生质体融合的研究。通过硫酸二乙酯（ＤＥＳ）诱变得到营养缺隐型菌株Ｑ（ａｒｇ－）和Ｋ（ｌｙｓ－,ρ－）,其融合率为１．２５×１０－５。检出的融合子其酒精发酵特性、细胞形态、体积大小都不同于双亲菌株。比较了在２８℃培养条件下,出发余株清酒酵母,Ｋ氏酿酒酵母和融合子Ｆ１、Ｆ２的发酵速度曲线、乙醇产量和酒精耐量等,得到一株在２８℃培养条件下,乙醇产量为７．４％（Ｖ／Ｖ）,酒精耐量为１５％的融合株Ｆ１。     

木糖代谢基因表达水平对酿酒酵母重组菌株产物形成的影响

以Ｅ．ｃｏｌｉ－Ｓ．ｃｅｒｅｖｉｓｉａｅ穿梭质粒ＹＥｐ２４为骨架,将树干毕赤酵母（Ｐｉｃｈｉａ ｓｔｉｐｉｔｉｓ ＣＢＳ６０５４）的木糖还原酶（ＸＲ）基因ＸＹＬ１及木糖醇脱氢酶（ＸＤＨ）基因ＸＹＬ１分别以不同的相对表达方向置于酿酒酵母的乙醇脱氢酶Ｉ（ＡＤＨ１）启动子和磷酸甘油激酶（ＰＧＫ）启动子下,构建不同ＸＹＬ１及ＸＹＬ２的重组质粒。这些重组质粒分别转化酿酒酵母（Ｈ１５８）受体菌。得到的重组菌株     

新生儿颊粘膜定植菌株的拮抗性研究

本文分离在新生儿颊粘膜上皮细胞表面形成微菌落、且初代培养时菌落较纯的１５株ａ溶血细菌,进行对Ｂ链球菌、金黄色葡萄球菌、绿脓杆菌、大肠杆菌４种共７株菌的体外拮抗实验。１５株菌中包括８株ａＳｔｒｅｐ．,其中Ｓｔｒｅｐ．ｍｉｔｉｓ４株,Ｓｔｒｅｐ．ｏｒａｌｉｓ２株、Ｓｔｒｅｐ．Ｓａｌｉｖ．Ｓａｌｉｖａｒｉｕｓ１株、Ｓｔｒｅｐ．ｉｎｔｅｒｍｅｄｉｕｓ１株;ＬＣ．ｌａｃｔｉｓ．ｃｒｅｍｏｒｉｓ５株、Ｇｅｍｅｌａｍｏｒｂｉｌｏｒｕｍ１株、Ｇｅｍｅｌａｈａｅｍｏｌｙｓａｎｓ１株。结果约６０％（９／１５）的颊粘膜定植株对两株及两株以上的病原菌株或阴性杆菌株有拮抗作用,只对１株菌有损坏抗作用的ａ溶血菌４株,完全无拮抗作用的菌株２株;ａＳｔｒｅｐ．、ＬＣ．ｌａｃｔｉｓ．ｃｒｅｍｏｒｉｓ的拮抗作用较强;拮抗作用的有无、强弱有很强的菌株特异性     

金属硫蛋白产生菌的诱变育种

采用亚硝基胍和紫外线诱变,自金属硫蛋白（ＭＴ）产生菌酿酒酵母（ｄｅｃｃｈａｒｏｍｙｃｅｓｃｅｒｅｖｉｓｉａｅ）ＢＤ１０１－２５单倍体中获得遗传稳定的高Ｃｕ２＋、Ｃｄ２＋抗性突变株ＢＤ１０１－６９和ＢＤ１０１－３０。并对其重金属解毒、桔抗ｕ．ｖ．和６０Ｃｏ辐射效应、清除羟基自由基能力等生物学功能进行了研究。与出发菌株相比,上述生物学活性与酵母细胞对Ｃｉ２＋抗性、ＭＴ表达量表现出正相关性。两个突变株类ＭＴ表达量与生物学活性皆有所提高,为酿酒酵母ＭＴ的理论和应用研究打下了基础。     

黑木耳电泳核型分析

采用等高锁状均质电场（ＣＨＥＦ）凝胶电泳技术,对黑木耳（Ａｕｒｉｃｕｌａｒｉａ ａｕｒｉｃｕｌａ）电泳核型进行分析,以酿酒酵母（Ｓａｃｃｈａｒｏｍｙｃｅｓ ｃｅｒｅｖｉｓｉａｅ）菌株ＹＰＨ７５５和粟酒裂殖酵母（Ｓｃｈｉｚｏｓａｃｃｈａｒｏｍｙｃｅｓ ｐｏｍｂｅ）菌株ＡＳ２．２１４的染色体ＤＮＡ大小作为分子量标记,估计黑木耳基因组中至少包含９条ＤＮＡ分子量在８５０ｋｂ至５８００ｋｂ之间的染色体,     

CO_2激光与γ射线辐照花生的效应研究

ＣＯ￣２激光对花生的诱变效应跟￣５０Ｃｏ－γ射线对花生的诱变效应相仿,能诱发花生根尖细胞染色体畸变,且畸变率随辐照剂量的增加而上升;也能使花生的一些生物学特征发生变异,其变异性状能向继代遗传。     

我国植物激光诱变育种的概况

我国植物激光育种１９７２年以来,共用１４种激光器处理了４５种植物,育成了４２个新品种,激光器的诱变效果,以Ｈｅ－Ｎｅ和ＣＯ２激光最好。     

CO_2激光辐射提高蔬菜种子活力的研究

本文总结了 CO2 激光辐射提高蔬菜种子活力的研究成果 ,适量 CO2 激光辐射蔬菜种子可增强种子活力 ,提高幼苗素质 ,增加产量 ,促进早熟 ,加强生理机能 ,改善解剖结构 ,提出一些需要解决的问题和对其进行的初步研究。     

紫外-激光复合诱变选育天冬氨酸转氨酶高产菌株

对天冬氨酸转氨酶产生菌大肠杆菌XJ-1原生质体进行紫外-激光复合诱变筛选,结果表明,复合诱变对该菌的原生质体有明显的致死作用。以致死率和正突变率为指标,确定了紫外和He-Ne激光照射的最佳时间分别为45 s和40min。在此条件下对大肠杆菌原生质体进行紫外-激光复合诱变,得到3株高产菌株,分别命名为XJ-1-45、XJ-1-86和XJ-1-99,酶活较出发菌株XJ-1分别提高了12.82%、17.37%和26.27%。传代培养表明突变株生产性能稳定。     

CO_2激光照射对石刁柏种子活力指标的数学模拟

本文在 CO2 激光对石刁桕种子活力影响的研究基础上 ,应用多项式回归对种子活力指标进行了数学模拟。分别得到了发芽种子的胚根长、下胚轴长、发芽率、发芽指数、活力指数、出苗率与 CO2 激光照射时间的数学模型。     

Deficiencies of double-strand break repair factors and effects on mutagenesis in directly gamma-irradiated and medium-mediated bystander human lymphoblastoid cells

Using RNA interference techniques to knock down key proteins in two major double-strand break (DSB) repair pathways (DNA-PKcs for nonhomologous end joining, NHEJ, and Rad54 for homologous recombination, HR), we investigated the influence of DSB repair factors on radiation mutagenesis at the autosomal thymidine kinase (TK) locus both in directly irradiated cells and in unirradiated bystander cells. We also examined the role of p53 (TP53) in these processes by using cells of three human lymphoblastoid cell lines from the same donor but with differing p53 status (TK6 is p53 wild-type, NH32 is p53 null, and WTK1 is p53 mutant). Our results indicated that p53 status did not affect either the production of radiation bystander mutagenic signals or the response to these signals. In directly irradiated cells, knockdown of DNA-PKcs led to an increased mutant fraction in WTK1 cells and decreased mutant fractions in TK6 and NH32 cells. In contrast, knockdown of DNA-PKcs led to increased mutagenesis in bystander cells regardless of p53 status. In directly irradiated cells, knockdown of Rad54 led to increased induced mutant fractions in WTK1 and NH32 cells, but the knockdown did not affect mutagenesis in p53 wild-type TK6 cells. In all cell lines, Rad54 knockdown had no effect on the magnitude of bystander mutagenesis. Studies with extracellular catalase confirmed the involvement of H2O2 in bystander signaling. Our results demonstrate that DSB repair factors have different roles in mediating mutagenesis in irradiated and bystander cells.     

CO2激光对蚕豆诱变效应试验研究

７０年代以来,全国已有２０多个省市,近百个单位开展激光在农业上应用的研究,并对２０多种作物２００多个品种进行激光育种的研究。试验表明：激光在刺激作物生长,早熟增产以及诱发变异、改良品种等都有一定的效果,并培育出一些新品种应用于生产。然而,激光对作物的作用机制,特别是遗传机理方面的研究报道尚少。本试验目的是探讨ＣＯ２激光对蚕豆根尖细胞染色体畸变的影响及田间农艺性状的变异情况,分析细胞染色体畸变与农艺性状变异的相关性及其遗传传递情况,为作物激光诱变育种提供依据。本试验采用功率密度为３９４ｍＷ／ｃｍ２的ＣＯ２激光照射蚕豆萌动种子,观察其对蚕豆根尖细胞染色体畸变及幼苗生长的影响,探讨ＣＯ２激光照射后蚕豆植株农艺性状的变异及其遗传传递情况。试验结果表明：ＣＯ２激光不同时间照射蚕豆萌动种子,均能使根尖细胞产生染色体畸变,且畸变类型相似;同时,对Ｌ１幼苗生长有明显的抑制作用,Ｌ２植株高度、分枝数及结荚数等农艺性状均产生不同程度的变异。其中分枝数这一性状的变异能传递给Ｌ３,其余性状的变异则属生理损伤所致。     

Conformational modulation of human cytochrome P450 2E1 by ethanol and other substrates: a CO flash photolysis study

The alcohol-inducible cytochrome P450 2E1 is a major human hepatic P450 which metabolizes a broad array of endogenous and exogenous compounds, including ethanol, low-molecular weight toxins, and fatty acids. Several substrates are known to stabilize this P450 and inhibit its cellular degradation. Furthermore, ethanol is a known modulator of P450 2E1 substrate metabolism. We examined the CO binding kinetics of P450 2E1 after laser flash photolysis of the heme-CO bond, to probe the effects of ethanol and other substrates on protein conformation and dynamics. Ethanol had an effect on the two kinetic parameters that describe CO binding: it decreased the rate of CO binding, suggesting a decrease in the protein's conformational flexibility, and increased the photosensitivity, which indicates a local effect in the active site region such as strengthening of the heme-CO bond. Other substrates decreased the CO binding rate to varying degrees. Of particular interest is the effect of arachidonic acid, which abolished photodissociation in the absence of ethanol but had no effect in the presence of ethanol. These results are consistent with a model of P450 2E1 whereby arachidonic acid binds along a long hydrophobic binding pocket and blocks exit of CO from the heme region.     

Non-targeted mutagenesis of unirradiated lambda phage in Escherichia coli host cells irradiated with ultraviolet light

Non-targeted mutagenesis of lambda phage by ultraviolet light is the increase over background mutagenesis when non-irradiated phage are grown in irradiated Escherichia coli host cells. Such mutagenesis is caused by different processes from targeted mutagenesis, in which mutations in irradiated phage are correlated with photoproducts in the phage DNA. Non-irradiated phage grown in heavily irradiated uvr+ host cells showed non-targeted mutations, which were 3/4 frameshifts, whereas targeted mutations were 2/3 transitions. For non-targeted mutagenesis in heavily irradiated host cells, there were one to two mutant phage per mutant burst. From this and the pathways of lambda DNA synthesis, it can be argued that non-targeted mutagenesis involves a loss of fidelity in semiconservative DNA replication. A series of experiments with various mutant host cells showed a major pathway of non-targeted mutagenesis by ultraviolet light, which acts in addition to "SOS induction" (where cleavage of the LexA repressor by RecA protease leads to din gene induction): (1) the induction of mutants has the same dependence on irradiation for wild-type and for umuC host cells; (2) a strain in which the SOS pathway is constitutively induced requires irradiation to the same level as wild-type cells in order to fully activate non-targeted mutagenesis; (3) non-targeted mutagenesis occurs to some extent in irradiated recA recB cells. In cells with very low levels of PolI, the induction of non-targeted mutagenesis by ultraviolet light is enhanced. We propose that the major pathway for non-targeted mutagenesis in irradiated host cells involves binding of the enzyme DNA polymerase I to damaged genomic DNA, and that the low polymerase activity leads to frameshift mutations during semiconservative DNA replication. The data suggest that this process will play a much smaller role in ultraviolet mutagenesis of the bacterial genome than it does in the mutagenesis of lambda phage.