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991.
通过使用噬斑形成试验、透射电镜及检测志贺菌蛋白表达等方法,研究志贺菌对Hela细胞的侵袭能力。研究发现:37℃培养条件下,胞质内出现成堆的志贺菌;30℃培养条件下,细菌主要分布在细胞外。SDS-PAGE显示,与30℃培养条件相比,在37℃培养下,志贺菌表达蛋白质的种类和数量明显增加。噬斑形成发现,12株福氏志贺菌强毒株,有9株噬斑数>1000个/ml,而2株弱毒株噬斑数则在50个/ml以下。透射电镜证实了志贺菌对细胞的黏附、侵入和释放过程。结果表明:志贺菌对细胞的侵袭能力受温度的影响;不同志贺菌流行株对细胞的侵袭力存在着差异:实验也显示,应用HeLa细胞研究志贺菌侵袭力是一种简便易行且价廉的方法。 相似文献
992.
菜籽饼粕粗蛋白降解菌的筛选、初步鉴定与发酵条件摸索 总被引:1,自引:0,他引:1
在接种了本实验室保存的诱变菌株A的未灭菌的菜籽饼粕发酵样品中筛选得到3株能以 菜籽饼粕为原料生长的菌株,编号为S1、S2、S3,菌株A和这3株菌种通过鉴定确定为凝结芽孢杆 菌、圆孢芽孢杆菌、短小芽孢杆菌和球形芽孢杆菌。通过设计正交实验摸索出这4株菌种的最佳 培养条件。并对饼粕固体混合菌发酵进行了初步摸索和探讨。 相似文献
993.
对建兰规模化生产体系,包括园区建设、繁殖与栽培、日常管理、病虫害防治等主要环节进行规范化探讨,以期为建兰商品化生产提供参考。 相似文献
994.
Determining uptake of 'non-labile' soil
cadmium by Thlaspi caerulescens using
isotopic dilution techniques 总被引:3,自引:0,他引:3
JULIAN J. HUTCHINSON SCOTT D. YOUNG STEVE P. MCGRATH HELEN M. WEST COLIN R. BLACK & ALAN J. M. BAKER 《The New phytologist》2000,146(3):453-460
We assessed the ability of several populations of the metal-hyperaccumulator species, Thlaspi caerulescens , to mobilize non-labile cadmium in soils historically contaminated by Pb/Zn mine spoil or sewage sludge. Radio- labile Cd was determined chemically as an ' E -value', [Cd E ], and biologically as an ' L -value', [Cd L ]. For comparison, chloride-extractable Cd, [Cdchlor ], was also determined using 1 M CaCl2 as a single-step soil extractant. Values of [Cd L ] were measured for six populations of T. caerulescens that varied substantially in their ability to assimilate soil Cd, and a non-accumulator species with a similar growth habit, Lepidium heterophyllum . Seeds were sown in soil spiked with 109 Cd and grown for 9–12 wk in a controlled environment room. Values of [Cd L ] were determined from the specific activity of 109 Cd and concentration of Cd in the plant leaves. For the six soils studied, [Cd E ] ranged from 4.9 to 49% of total soil Cd [CdT ]. Values of [Cd L ] were, in general, in close agreement with both [Cd E ] and [Cdchlor ] and substantially less than [CdT ]. However, [Cd L ] showed no correlation with the concentration of Cd in plant tissue, [Cdshoot ]. This suggests that, in the soils studied, T. caerulescens did not mobilize non-labile soil Cd by producing root exudates or altering rhizosphere pH. The results imply that there may be significant restrictions to metal bioavailability, even to hyperaccumulator species, in heavily contaminated soils in which a large proportion of the metal may be present in 'non-labile' forms. 相似文献
995.
A novel protocol, based on biolistics and regeneration via organogenesis, was developed for genetic transformation of cassava
(Manihot esculenta Crantz). The in vitro performance of cassava cultivars CMC40, MPer183 and MCol22 was evaluated, and the regeneration protocol was modified to improve
shoot production from explants for transformation experiments. Somatic cotyledons were used as a target tissue in the transformation
experiments using the Particle Inflow Gun and a plasmid containing the uidA gene in transient assays. The effect of different parameters for particle bombardment efficiency, including the amount of
DNA used, the flying distance of the projectiles and the pre- and post-plasmolysis time of the target tissue, was evaluated
and the conditions were partially optimised. Stably transformed cassava plants of cvs. MCol22 and TMS60444 were produced using
the partially optimised conditions and two different vector constructs carrying the hpt gene as the selectable marker. The selection protocol was optimised further, and a rooting test was developed for screening
the regenerants for antibiotic resistance to reduce the number of escapes obtained after primary selection. The production
of stably transformed cassava lines and the expression of the transgenes was verified by Southern blot analysis and RT-PCR.
Received: 10 December 1999 / Revision received: 12 January 2000 / Accepted: 7 February 2000 相似文献
996.
José Brandão-Neto Carlos A. B Silva Nancy B. Figueiredo T. Shuhama Michele B.S. Holanda Juliana M.M. Diniz 《Biometals》2000,13(2):141-145
Zinc has an important role in the control of carbohydrate metabolism, and diabetic patients are at risk for zinc deficiency. However, there are conflicting data concerning nutritional zinc status. In order to investigate this topic, 10 normal and 10 insulin-dependent diabetic patients were studied following venous zinc tolerance test. Our results found no evidence of zinc deficiency or of changes on the kinetic parameters of zinc in patients with insulin-dependent diabetes mellitus following a venous zinc tolerance test. 相似文献
997.
998.
诸葛菜茎叶中黄酮类化合物的研究 总被引:4,自引:0,他引:4
诸葛菜茎叶乙醇提取物用Mg+HCl,Zn+HCl,1%FeCl3-乙醇液,1%NaOH进行显色反应,呈现黄酮类化合物性质特征颜色。又以槲皮素,山柰酚,异鼠李素为对照品,采用HPLC法分析测定了其茎叶中黄酮醇的含量。结果表明干品中总黄酮含量(以甙元计)为0.568%。 相似文献
999.
Kerstin Tegethoff Bernd A. Herbold Ernst M. Bomhard 《Mutation Research - Genetic Toxicology and Environmental Mutagenesis》2000,470(2):275
The genotoxic potential of 1,4-dichlorobenzene (1,4-DCB) has been extensively evaluated in vitro and in vivo. The majority of the studies demonstrated the absence of a genotoxic potential for 1,4-DCB. At variance are a bone marrow micronucleus test (MNT) after intraperitoneal (i.p.) treatment of NMRI mice [Mohtashamipur et al., Mutagenesis 2 (1987) 111–113] and a gene mutation assay on mouse lymphoma cells [McGregor et al., Environ. Mol. Mutagen. 12 (1988) 85–145]. Therefore, we investigated 1,4-DCB and its main metabolite 2,5-dichlorophenol (2,5-DCP) for both endpoints. In an MNT, male and female NMRI mice were treated orally with single doses of 2500 mg/kg 1,4-DCB and 1500 mg/kg 2,5-DCP, respectively. Smears were prepared 24, 48 and 72 h thereafter. No induction of micronuclei was detected for both compounds. Also under the conditions of Mohtashamipur et al. (1987), intraperitoneal treatments of male and female mice with 2 × 177.5 and 2 × 355 mg/kg 1,4-DCB failed to induce micronuclei. In addition, CHO/HPRT-gene mutation tests with 1,4-DCB and 2,5-DCP yielded negative results for both compounds with and without metabolic activation system. Therefore, 1,4-DCB and 2,5-DCP are considered to be non-mutagenic in these test systems. 相似文献
1000.
从千层塔中微波协助提取石杉碱甲和石杉碱乙 总被引:7,自引:0,他引:7
首先从 8种溶剂中筛选出硫酸作为微波协助提取的浸提溶剂 ,然后用正交试验确立了千层塔生物碱的最佳提取条件。以石杉碱甲和石杉碱乙回收率为指标 ,考察了溶剂倍数、溶剂浓度、微波处理时间等因素。结果表明 ,在室温下微波协助提取的最优条件为 :酸浓度 0.8% (v/v) ,液固比例 2 5∶1 ,微波处理时间 90s。 3次重复实验所得石杉碱甲和石杉碱乙回收率分别是 93.7%和 93.9% ,相对标准偏差分别为 1.79%和 1.5 6% (n =3)。与传统的回流提取工艺相比 ,过程时间从 2h缩短为 90s,回收率提高了 1 0 %以上。 相似文献