Efficient method for selection of auxotrophic mutants of Neurospora

A technique for the selection of induced and spontaneous auxotrophic mutants of Neurospora in relatively high frequency is described. The method takes advantage of the reduced rate of death of germinating conidia of an inositol-requiring strain when a secondary mutation is imposed.     

Selecting bacterial mutants by the penicillin method

Certain improvements are described in the use of penicillin for isolating auxotrophic mutants of bacteria. By obtaining exponential growth before the penicillin is added, and by minimizing the duration of the treatment, cross-feeding is decreased and much denser populations can be screened. These modifications have made it possible to obtain, with regularity, mutants of Escherichia coli blocked in a desired step in arginine biosynthesis.     

Tryptophan- and indole-excreting bacterial mutants

Prototrophic mutants of Escherichia coli capable of producing indole and tryptophan were obtained by selecting for resistance to antimetabolites. An anthranilic acid auxotroph grown under conditions which would derepress the tryptophan synthetase system would also accumulate substantial quantities of L-tryptophan.     

茄子抗黄萎病突变体离体筛选Ⅱ.突变体筛选

针对茄子黄萎病育种中缺乏高抗材料，作者利用生物技术和理化诱变技术，开展了茄子抗黄萎病突变体的离体筛选，并获得得一株黄萎病抗性为中抗(病情指数为23．0)、农艺性状较好的“三月茄”突变体(142-E)，其自交群体的染色体也与三月茄野生型相同。     

EMS诱变处理定向筛选杨树耐盐突变体研究

应用EMS(甲基磺酸乙酯)处理杨树胚性愈伤组织,通过组织培养方法定向筛选杨树耐盐变异体。对EMS处理"加引"杨树胚性愈伤组织的浓度和时间进行了研究,结果表明:在同一EMS浓度下,随着处理时间的增加,胚性愈伤组织分化芽的比率降低;处理相同时间,随着EMS浓度增加,胚性愈伤组织分化芽的比率降低;不同EMS浓度处理后的胚性愈伤组织分化芽的比率与处理时间呈线性关系。约200万胚性细胞经4‰(V/V)浓度EMS处理36 h,并经逐级耐盐定向筛选,可得在含NaCl 0.5%(m/V)的培养基上生根的组培苗40株。经筛选优系,组培成再生植株,进行植株水平的试管内耐盐性检测,结果表明:诱变处理所得植株与对照相比,其耐盐性明显提高。同时,在未经耐盐定向筛选实验中得到29株叶片颜色发生变异的畸变植株,耐盐定向筛选试验中也得到4株同类型畸变植株。     

Sparing of folinic acid by thymidine

Thymidine, which is inactive when added alone to Pediococcus cerevisiae (Leuconostoc citrovorum) 8081, was found to increase its growth in the presence of folinic acid. The addition of thymidine increased both the sensitivity of the folinic acid assay and the total growth yield. The mechanism of the synergistic effect of thymidine is briefly discussed.     

农杆菌介导法构建里氏木霉ura3基因突变体的研究

构建了ura3缺失基因载体pEMT-△ura3,采用农杆菌介导法转化里氏木霉QM9414,在含尿嘧啶核苷(1.87 mg.mL-1)和五氟乳氰酸(5-FOA,5 mg.mL-1)的筛选培养基上筛选转化子,经表型验证和PCR检测,获得ura3基因缺失突变体1株,ura3基因的同源重组率为16.6%。采用农杆菌介导法将黑曲霉的pyrA基因导入ura3基因缺失突变体中,使其回复野生型表型,从而建立了以pyrA基因作为筛选标记的里氏木霉受体菌株。     

Selection of Trichoderma mutants with enhanced cellulase production and resistant to catabolite repression

Due to high cost and relatively low efficiency of cellulase enzymes used for the saccharification of pretreated lignocelluloses, the improvement of cellulase secreting microorganisms is of vital importance. Trichoderma reesei QM 6a, an excellent source of cellulase was selected in the late 1960's. at Natick Laboratories by its performance on pure cellulose (Solka Floc, Avicel) . QM 6a is the wild parent strain of best existing hypercellulolytic mutants such as Rut C30, VTT-D-80133, L…     

Axonal transport of tritium-labeled putrescinein the embryonic visual system of zebrafish

The transport of [(3)H]putrescine is demonstrated by autoradiography in the retino-tectal tract of Brachydanio rerio embryos. Transport of [(3)H]putrescine appears to be more rapid than that of tritium-labeled protein and is not inhibited by a colchicine effect on axonal neurotubules as is protein transport. The radioactivity transported to the brain is found, on electrophoresis, in the putrescine fraction.     

香椿细菌性叶斑病药剂筛选及毒力测定

香椿叶斑病是近年来在山东香椿种植地发现的一种新的细菌性病害,经初步鉴定引起该病害的病原菌有黄单胞杆菌群（Xanthomonas）和短小杆菌群（Curtobacterium）两种。为控制该病害的扩展蔓延,采用抑菌圈法从44种杀菌剂中筛选出具有较好抑菌作用的药剂12种。室内药剂筛选及毒力测定结果表明：50％福美双、12．5％消斑灵、50％复方硫菌灵、50％代森锰锌对香椿细菌性叶斑病菌抑制的有效中浓度最小,抑菌效果最好,EC50分别为：380．2477、368．0665、477．3424、827．0339mg／L;其次为25％戊唑醇、70％甲基托布津、40％福美砷、抗菌1号、50％多菌灵,EC∞分别为：3145．7695、3251．2780、5711．1100、5928．0692、6724．3608mg／L。     

Uptake of tritium-labeled norepinephrine in brain and other tissues of cat in vitro

Slices of cat cerebral cortex, heart, and spleen that have been incubated in media containing approximately 5 to 25 mmicrog of dl-norepinephrine-7H(8) per milliliter contain levels of isotopic amine greater than those in the medium. The effects of norepinephrine concentration, reserpine, and ouabain on the uptake suggest that the amine enters cells both by diffusion and by a concentrating miechanism that is saturated at low levels of norepinephrine. The drugs inhibit the latter.     

茄子抗黄萎病突变体离体筛选Ⅰ.粗毒素制备

茄子黄萎病在世界各地均有发生，且危害严重。研究表明：缺乏抗源已成为制约茄子抗黄萎病育种的瓶颈，突变体筛选是创造新的茄子黄萎病抗材料重要方法之一。获得强致病力的粗毒素是该技术体系中的关键。本文采用茄子茎尖接种法开展茄子黄萎病粗毒素的致病力研究，并获得了致病力强的粗毒素用于抗性突变体的离体筛选。     

海南甜瓜细菌性角斑病防治药剂筛选试验

进行6种药剂对甜瓜细菌性角斑病防治效果试验.结果显示,6种药剂中表现最好的是20%二氯异氰尿酸钠可湿性粉剂750倍液,其药后5d对甜瓜细菌性角斑病的防治效果为69.3%,53.8%可杀得2000干悬浮剂1000倍液和20%叶青双可湿性粉剂750倍液对甜瓜细菌性角斑病也有一定的防治效果,而其他3种供试药剂防效较差,基本上没有表现出对该病害的控制作用.因此,生产中主要以20%二氯异氰尿酸钠可湿性粉剂为推荐药剂,但在使用过程中该药剂的可溶性较差,建议各生产厂家对该药剂进行改良.     

中华鳖细菌疫苗免疫佐剂的筛选及其初步应用

将分离自中华鳖Trionyx sinensis主要细菌性疾病—肠道出血性败血症、鳖穿孔病（疖疮病）、红脖子红底板病、鳖腐皮病的4株病原菌,在体积分数为3．5％的福尔马林溶液中灭活24h。在灭活的4株菌中添加不同佐剂,充分混匀后分别制备成总含菌量为6×10^9个／mL的4价菌苗,分别免疫8只ICR小鼠,并设不加佐剂免疫组及空白组作为对照。经3次免疫后,随机选3只小鼠抽血制备血清,用间接ELISA方法测定抗体效价,除空白对照组外,其它4组小鼠的免疫血清效价为1：1．6×10^4-1：2．56×10^5,各免疫组的效价依次为弗氏佐剂〉白油佐剂〉蜂胶佐剂〉不加佐剂。另外5只小鼠用于免疫保护性试验。结果表明：3种佐剂的免疫保护率均为100％,而不加佐剂组免疫保护率为80％,空白对照组死亡率为100％。考虑到弗氏佐剂的成本较高且白油佐剂有副作用,故选择蜂胶作为免疫佐剂,制备了中华鳖4价菌苗。用该菌苗免疫接种50只体重为100～150g／只的健康中华鳖,注射剂量为0．2mL／只,并设置对照组（注射等量的生理盐水）,共接种20只健康中华鳖。分别于免疫后第20、30、40、50天随机采集3只受免疫的中华鳖和对照组的1只中华鳖血液并制备血清,用浙江省淡水水产研究所制备的针对中华鳖IgM的单抗3H3介导的ELISA方法,测定血清中的抗体效价。结果表明：当中华鳖免疫后40d,血清中抗体效价达到最高,为1：6．4×10^4;免疫后50d将受免中华鳖分成4组,分别用4种菌株以5LD50（9×10^6个／mL）进行攻毒试验（0．5mL／只）,结果免疫保护率均达到100％,而对照组死亡率均为100％。     

中华鳖细菌疫苗免疫佐剂的筛选及其初步应用

将分离自中华鳖Trionyxsinensis主要细菌性疾病——肠道出血性败血症、鳖穿孔病(疖疮病)、红脖子红底板病、鳖腐皮病的4株病原菌,在体积分数为3.5%的福尔马林溶液中灭活24 h。在灭活的4株菌中添加不同佐剂,充分混匀后分别制备成总含菌量为6×109个/mL的4价菌苗,分别免疫8只ICR小鼠,并设不加佐剂免疫组及空白组作为对照。经3次免疫后,随机选3只小鼠抽血制备血清,用间接ELISA方法测定抗体效价,除空白对照组外,其它4组小鼠的免疫血清效价为1∶1.6×104～1∶2.56×105,各免疫组的效价依次为弗氏佐剂>白油佐剂>蜂胶佐剂>不加佐剂。另外5只小鼠用于免疫保护性试验。结果表明:3种佐剂的免疫保护率均为100%,而不加佐剂组免疫保护率为80%,空白对照组死亡率为100%。考虑到弗氏佐剂的成本较高且白油佐剂有副作用,故选择蜂胶作为免疫佐剂,制备了中华鳖4价菌苗。用该菌苗免疫接种50只体重为100～150 g/只的健康中华鳖,注射剂量为0.2 mL/只,并设置对照组(注射等量的生理盐水),共接种20只健康中华鳖。分别于免疫后第20、30、40、50天随机采集3只受免疫的中华鳖和对照组的1只中华鳖血液并制备血清,用浙江省淡水水产研究所制备的针对中华鳖IgM的单抗3H3介导的ELISA方法,测定血清中的抗体效价。结果表明:当中华鳖免疫后40 d,血清中抗体效价达到最高,为1∶6.4×104;免疫后50 d将受免中华鳖分成4组,分别用4种菌株以5LD50(9×106个/mL)进行攻毒试验(0.5 mL/只),结果免疫保护率均达到100%,而对照组死亡率均为100%。     

Bacterial growth rate in the sea: direct analysis by thymidine autoradiography

Autoradiography with tritiated thymidine was used to study microbial growth directly in nature. The epiphyte Leucothrix mucor was used since it is a large filamentous bacterium with a characteristic morphology making it recognizable in natural collections. The technique was developed initially with pure cultures. The relation between growth rate and the rate of accumulation of radioactive cells permitted derivation of a constant for use in calculating growth rate in natural material and in two-membered cultures of L. mucor growing epiphytically on pure cultures of marine algae. The growth rate (generation time) in two-membered cultures with the red alga Antithamnion sarniense was 94 minutes under the conditions used. In nature the growth rate of a sample from Iceland was 685 minutes; that of a sample from Long Island Sound was 660 minutes. There was no evidence of preferential growth in the basal portion of bacterial filaments nearest the algal surface. However, filamentous growth in nature, but not in pure or two-membered culture, was nonrandom, growth being clustered in some regions.     

Screening and identification of mutants of Magnaporthe grisea by REMI

The plasmid pUCATPH was used to establish a transformation system in wild-type isolate M131 of Magnaporthe grisea. Six hundred and thirty-nine transformants were obtained by restriction enzyme-mediated integration (REMI) with hygromycin B (hyg B) resistance as a tag. Morphological analysis of two of the REMI mutants confirmed that they produced little melanin under black light and continued for three generations. Pathogenicity identification of six mutants screened proved that they made pathogenicity changes on three sets of differential varieties with different resistance genes. Rep-PCR analyses showed that two morphological mutants and two pathogenicity mutants differed from wild-type isolate M131 at the molecular level. RFLP analyses were performed to study the four mutants at the molecular level and the integration sites of the plasmid DNA. The results showed that the plasmid was inserted into all four mutants and that the insertion sites were random. Translated from Journal of Yangzhou University (Agricultural and Life Science Edition), 2006, 27(2): 91–94 [译自: 扬州大学学报]     

稻瘟病菌REMI突变体的筛选和鉴定

利用构建的含潮霉素(HygB)抗性标记的质粒pUCATPH在稻瘟病菌菌株M 131中建立一个转化体系,通过限制酶介导整合(REM I)插入诱变技术,以HygB抗性作为突变体筛选标记,获得639个转化子。对其中200个转化子进行表型和致病性测定后,通过点杂交鉴定分别获得6个致病性突变菌株和部分表型突变菌株。对2个表型突变菌株和rep-PCR图谱差异性较大的2个致病性突变菌株进行RFLP分析,结果表明:突变体中均已插入质粒,但转化质粒在M 131中整合具有一定的随机性。