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101.
利用人粒细胞集落刺激因子(hG-CSF)cDNA3′端非翻译区(3′-UTR)中存在的DraⅠ酶切位点,通过部分酶切与完全酶切,删除3′-UTR不同长度,构建了四种hG-CSFcDNA瞬时重组表达质粒。转染COS-7细胞后,生物活性测定结果提示,hG-CSFcDNA3′-UTR对其表达起负调控作用,其关键性序列位于紧接终止密码子TGA下游的65bp范围内,3′-UTR对hG-CSFcDNA表达的影响与转录水平的差别有一定关系。 相似文献
102.
利用KCN、H_2O2和SDS的选择性反应引起的SOD同工酶谱带变化即可鉴别粗抽提液中的SOD同工酶类型;用这种方法对五株不同种根霉的鉴别实验表明,它们均不同程度地含有Cu,Zn型和Mn型两种SOD,前者约占80%左右,后者只占20%左右。用邻苯三酚自氧化法对样品中SOD活性测定结果与在同工酶谱上的鉴别结果基本一致。 相似文献
103.
Gloria Giacomini Santo V. Nicosia Beatriz O. Saunders Caroline Fultz X. Sun Valerio M. Jasonni 《In vitro cellular & developmental biology. Animal》1995,31(4):300-309
Summary The ovarian mesothelium (OM) represents the tissue of origin of ovarian epithelial cancer. To gain insight into the regulation
of this tissue, OM organoids and submesothelial ovarian stromal cells (SC) were isolated from New Zealand White rabbits by
a stepwise tissue dispersal technique, while granulosa cells (GC) were aspirated from mature follicles (14±4 groups/animal).
OM and SC dispersal were sequentially accomplished by: a) 1-h incubation in collagenase type I (300 U/ml), gentle scraping
of the ovarian surface, and 1 g sedimentation of OM organoids (equivalent to 0.93±0.40 × 106 cells/animal) on 5% bovine serum albumin (BSA); b) 2-h incubation in pronase-collagenase (0.5%–300 U/ml) under periodical
resuspension and gentle scraping of SC (1.40±0.25 × 106/animal) from OM-denuded ovaries. After a week-long in vitro expansion, OM cells (OMC) were cultured alone and with SC or
GC within monocameral vessels or bicameral transfilter vessels in serumless, fibronectinrich (4μg/ml) HL-1 medium. After 7
d of contact cell-cell interaction, cytokeratin-positive OMC became surrounded by fibroblastoid, vimentin-positive SC or by
cytokeratin and vimentin-weakly positive GC. Filter-bound OMC humorally interacting with underlying SC or GC displayed a biphasic,
epithelioid and spindle, morphology with universal cytokeratin expression. Bromo-2′-deoxyuridine (BrdU) immunoperoxidase revealed
mean cell proliferation indices of 14.88% for OMC cultured alone, 11.21% and 19.39% for OMC cultured with GC or SC in monocameral
dishes, and 15.25% or 22.47% for OMC cultured in bicameral vessels over GC or SC, respectively. This model provides an experimental
tool for investigating the unexplored role of stromal-mesothelial interaction in OM pathobiology. 相似文献
104.
Caroline D. Perkins A.Michael Davidson Martin J. Day John C. Fry 《FEMS microbiology ecology》1994,15(1-2):33-44
Abstract The kinetics of conjugation, retrotransfer and mobilisation were studied at 5–15 min intervals between strains of Pseudomonas putida using plasmid pQKH6, isolated from river epilithon, and R300B. Transconjugants from the direct conjugation of pQKH6 and mobilisation of R300B by pQKH6 appeared rapidly, reaching maximum densities within 30–60 min of the start of both filter and liquid mating experiments. However, retrotransconjugants only appeared after a delay. This delay was short (approx. 45–60 min) in filter mating and much longer (2–5 h) for liquid mating experiments. Attempts at predicting the time course of retrotransconjugant development from (1) numbers of transconjugants from the conjugation and mobilisation experiments and (ii) mathematical models based on a mass action approach, both failed to reproduce the observed delay. It was concluded that retrotransfer did not proceed by either a one-step mechanism occuring early in conjugation or two separate conjugation and mobilisation steps. The clear demonstration of a delay in retrotransconjugant formation implies that a new mechanism must be sought. The likely importance of retrotransfer in the environment is discussed. 相似文献
105.
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
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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
106.
Simultaneous occurrence of fumonisin B1 and other mycotoxins in moldy corn collected from the People's Republic of China in regions with high incidences of esophageal cancer. 总被引:7,自引:1,他引:6
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A total of 31 corn samples collected from households in the counties of Cixian and Linxian of the People's Republic of China, where high incidences of esophageal cancer have been reported, were analyzed for fumonisin B1 (FB1), aflatoxin, and total trichothecene mycotoxins. High levels of FB1 (18 to 155 ppm; mean, 74 ppm) were found in 16 of the samples that showed heavy mold contamination. FB1, at lower levels (20 to 60 ppm; mean, 35.3 ppm), was also found in 15 samples, collected from the same households, that did not show any visible mold contamination. The levels of aflatoxin in the samples were low (1 to 38.4 ppb; mean, 8.61 ppb). High levels of total type-A trichothecenes were also found in the moldy corn samples (139 to 2,030 ppb; mean, 627 ppb). Immunochromatography of selected samples revealed that these samples contained T-2 toxin, HT-2 toxin, iso-neosolaniol, monoacetoxyscirpenol, and several other type-A trichothecenes. The concentration of total type-B trichothecenes in 15 moldy corn samples was in the range of 470 to 5,826 ppb (mean, 2,359 ppb). High levels (3.7 to 5.0 mg/g) of FB1 were produced in corn in the laboratory by five Fusarium moniliforme strains isolated from the moldy corn. These fungi were also capable of forming various nitrosamines (5 to 16 micrograms per flask) in the presence of nitrate and precursor amines.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
107.
108.
109.
Konieczny and Ausubel have described a technique whereby Arabidopsis thaliana loci can be rapidly mapped to one of the ten chromosome arms using a small number of F2 progeny from crosses between the ecotypes Landsberg erecta and Columbia. The technique involves the use of 18 co-dominant, cleaved amplified polymorphic sequence (CAPS) markers which are evenly distributed throughout the Arabidopsis genome. We have mapped these 18 markers using recombinant inbred (RI) lines generated in our laboratory. These data enable a better integration of loci mapped relative to the CAPS markers into the restriction fragment length polymorphism (RFLP) map generated using Arabidopsis RI lines. 相似文献
110.
Dong-Her Wu Chiou-Yen Wen Long-Liu Lin Wen-Shen Chu Wen-Hwei Hsu 《Letters in applied microbiology》1994,19(2):67-69
The isoamylase activity of Pseudomonas amyloderamosa WU 5315 was stable over the pH range from 5.5 to 6.25 while only about 30% of the activity remained at pH 6.5. Low isoamylase activity (418 U ml-1 ) was produced by the cells grown at high pH. Activity reached almost 3000 U ml-1 when pH was kept below 6.0 during the fermentation. With 1% glucose plus 2% maltose instead of 3% maltose as carbon source, however, no pH control was required and the isoamylase activity of Ps. amyloderamosa WU 5315 increased to 3400 U ml-1 . 相似文献