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51.
DNaseⅠ超敏感位点的研究能够发现潜在的调控基因转录活化的位点,比较正常人外周血有核细胞,淋巴瘤细胞株P3HR1和人鼻咽癌低分化磷癌细胞株HOnE1和HNE2中Ha-ras-1瘤基因的DNaseⅠ超敏感位点发现,只有HONE1和HNE2细胞基因组中存在一个DNaseⅠ超敏感位点,位于第一个外显子上游0.37kb处,上述结果提示正常白细胞和P3HR1细胞中Ha-ras-1基因处于失活状态,而在鼻咽癌细胞基因组中则处于活化状态,它的活化可能与0.37kb处的DNA序列有密切的关系。 相似文献
52.
Margarete Traiser Bernd Diener Dietmar Utesch Franz Oesch 《In vitro cellular & developmental biology. Animal》1995,31(4):266-273
Summary In primary monocultures of adult rat liver parenchymal cells (PC), the activities of the xenobiotic metabolizing enzymes microsomal
epoxide hydrolase (mEHb), soluble epoxide hydrolase (sEH), glutathione S-transferases (GST), and phenolsulfotransferase (ST) were reduced after 7
d to values below 33% of the initial activities. Furthermore, the gap junctional intercellular communication (GJIC), measured
after microinjection by dye transfer, decreased from 90% on Day 1 to undetectable values after 5 d in monoculture. Co-culture
of PC with nonparenchymal rat liver epithelial cells (NEC) increased (98% on Day 1) and stabilized (82% on Day 7) the homotypic
GJIC of PC. Additionally, most of the measured xenobiotic metabolizing enzyme activities were well stabilized over 1 wk in
co-culture. Because GJIC is one of several mechanisms playing an important role in cell differentiation, the importance of
GJIC for the stabilization of xenobiotic metabolizing enzymes in PC was investigated. PC in monoculture were, therefore, treated
with 2% dimethyl sulfoxide (DMSO), a differentiation promoting factor, and 1,1,1-trichloro-2,2,-bis (p-chlorophenyl) ethane
(DDT) (10 μg/ml), a liver tumor promotor and inhibitor of GJIC, was given to co-cultures of PC with NEC. DMSO significantly
stabilized (68% on Day 7), while DDT significantly inhibited (8% on Day 7) homotypic GJIC of PC in the respective culture
systems. In contrast, the activities of mEHb, sEH, GST, and ST were not affected in the presence of DMSO or DDT. These results lead to the assumption that the differentiation
parameters measured in this study (i.e., homotypic GJIC and the activities of xenobiotic metabolizing enzymes) are independently
regulated in adult rat liver PC. 相似文献
53.
Peter E. Molloy Barbara M. Graham Pauline M. Cupit Steven D. Grant Andrew J. R. Porter Charles Cunningham 《Molecular biotechnology》1995,4(3):239-245
This work describes protocols for the production of single-chain antibody and T-cell receptor fragments inE. coli. A choice of methods is given for the purification of the recombinant fragments that rely on the use of either immunoaffinity
or metal chelate affinity chromatography. The TCR fragments may have to be denatured and refolded before the fragments attain
their proper conformation. 相似文献
54.
Ingrid Ahrenholtz Michael G. Lorenz Wilfried Wackernagel 《Archives of microbiology》1994,161(2):176-183
A quantitative endonuclease assay, which relies on the introduction of single and double strand breaks into supercoiled plasmid DNA, was used to study the activity of the extracellular nuclease of Serratia marcescens SM6 in buffer and in groundwater. The parallel enzyme concentration-dependent production of relaxed and linear plasmid molecules suggests that the nuclease produces single and double strand breaks in duplex DNA. Bovine serum albumin stimulated the nuclease activity towards DNA and RNA and increased the stability of the enzyme against thermal inactivation. The DNase activity at 4 °C and 50 °C was almost half of that at the optimum temperature (37 °C). The nuclease was active in groundwater, although the specific activity was lower than in buffer. In a groundwater aquifer microcosm, mineral-adsorbed transforming DNA was substantially less accessible to the nuclease than was dissolved DNA. The data suggest that the extracellular nuclease of Serratia marcescens may contribute to DNA turnover in the environment and that adsorption of DNA to minerals provides protection against the nuclease.Abbreviations GW groundwater
GWA groundwater aquifer 相似文献
55.
The extremely thermophilic, obligately aerobic bacterium Sulfolobus solfataricus forms the tetrapyrrole precursor, -aminolevulinic acid (ALA), from glutamate by the tRNA-dependent five-carbon pathway. This pathway has been previously shown to occur in plants, algae, and most prokaryotes with the exception of the -group of proteobacteria (purple bacteria). An alternative mode of ALA formation by condensation of glycine and succinyl-CoA occurs in animals, yeasts, fungi, and the -proteobacteria. Sulfolobus and several other thermophilic, sulfur-dependent bacteria, have been variously placed within a subgroup of archaea (archaebacteria) named crenarchaeotes, or have been proposed to comprise a distinct prokaryotic group designated eocytes. On the basis of ribosomal structure and certain other criteria, eocytes have been proposed as predecessors of the nuclear-cytoplasmic descent line of eukaryotes. Because aplastidic eukaryotes differ from most prokaryotes in their mode of ALA formation, and in view of the proposed affiliation of eocytes to eukaryotes, it was of interest to determine how eocytes form ALA. Sulfolobus extracts were able to incorporate label from [1-14C]glutamate, but not from [2-14C]glycine, into ALA. Glutamate incorporation was abolished by preincubation of the extract with RNase. Sulfolobus extracts contained glutamate-1-semialdehyde aminotransferase activity, which is indicative of the five-carbon pathway. Growth of Sulfolobus was inhibited by gabaculine, a mechanism-based inhibitor of glutamate-1-semialdehyde aminotransferase, an enzyme of the five-carbon ALA biosynthetic pathway. These results indicate that Sulfolobus uses the five-carbon pathway for ALA formation.Abbreviations AHA
4-amino-5-hexynoic acid
- ALA
-aminolevulinic acid, Gabaculine, 3-amino-2,3-dihydrobenzoic acid
- GSA
glutamate 1-semialdehyde 相似文献
56.
Aphid activities during sieve element punctures 总被引:13,自引:0,他引:13
Aphid salivation in sieve elements and phloem sap ingestion were linked to waveforms in the Electrical Penetration Graph (EPG).
Non-viruliferousRhopalosiphum padi (L.) (Hemiptera, Aphididae) on barley yellow dwarf virus (BYDV) infected wheat could acquire the virus, which was used as
an indication for phloem sap ingestion, whereas virus inoculation by viruliferous aphids on healthy plants was associated
with salivation in sieve elements or other phloem cells. Probing was monitored and the waveforms recorded were related to
ELISA results of test plants. The EPG patterns A, B, and C are indicative of the stylet pathway phase, whereas patterns E1
and E2 reflect the phloem (sieve element) phase with an unknown activity (E1) or with ingestion and concurrent salivation
(E2). Aphids showing pathway and E1 rarely acquired virus, suggesting that little or no phloem sap ingestion can occur during
these patterns, whereas those showing additionally pattern E2 did so substantially, indicating phloem sap ingestion. The main
pattern related to virus inoculation was E1, although some aphids were able to inoculate plants during pathway. Pattern E1
clearly reflects the most important salivation into sieve elements. Pattern E2 had no clear contribution to virus inoculation,
supporting the present hypothesis that during this pattern the saliva is mixed with the phloem sap in the single canal at
the stylet tips and ingested immediately, without reaching the plant tissue. Sustained sap ingestion did not affect virus
inoculation. So, BYDV inoculation mainly occurs during the first period of a sieve element puncture which is always formed
by E1. Implications on persistent virus transmission are discussed. 相似文献
57.
Mark L. Carpenter Sarah A. Cassidy Keith R. Fox 《Journal of molecular recognition : JMR》1994,7(3):189-197
We have studied the interaction of the GC-specific, minor groove-binding ligand, mithramycin, with cloned DNA inserts containing isolated GC and CG sites flanked by regions of (AT)n and An · Tn using DNase I and hydroxyl radical footprinting. We find that mithramycin binds to GC better than CG and that AGCT is a better site than TGCA. Sites flanked by (AT)n appear to be bound better than those surrounded by An · Tn. Although no footprints are produced at T9GCA9 and T15CGA15, DNase I cleavage is enhanced with the GC sites suggesting that there is some interaction with the ligand. Mithramycin also alters the DNase I cleavage of (GA)n · (CT)n. 相似文献
58.
Four out of 187 strains, from enrichment cultures of dibenzothiophene (DBT), grew on DBT or thiophene 2-carboxylate as S sources. The four isolates, presumptively identified as Agrobacterium sp., Xanthomonas sp. and Corynebacterium spp., individually and together desulphurized DBT, producing 2-hydroxybiphenyl and sulphate.M. Constanti and A. Bordons are with the Departament de Bioquímica i Biotecnologia, and J. Giralt is with the Departament d'Enginyeria Química, both of the Universitat Rovira i Virgili, Pl. Imperial Tarraco 1, 43005 Tarragona, Catatonia, Spain 相似文献
59.
G. León M. A. Martinez J. P. Etchegaray M. I. Vera J. Figueroa M. Krauskopf 《World journal of microbiology & biotechnology》1994,10(2):149-153
To obtain specific DNA probes for the identification of the fish pathogen, Renibacterium salmoninarum, a discriminatory recombinant DNA library was constructed using selective fragments of the bacterial genome. Three renibacterial clones, pMAM29, pMAM46 and pMAM77, containing 149, 73, and 154 bp respectively, were isolated and characterized. The specificity of the probes was confirmed by dot-blot and Southern hybridization analyses. Bacterial hybridization experiments revealed that pMAM29 discriminates the R. salmoninarum genome from that of other fish pathogens such as Aeromonas salmonicida, Yersinia ruckeri, Flexibacter columnaris, Lactobacillus piscicola, Vibrio ordalii, Vibrio anguillarum and Aeromonas hydrophila. Thus, this probe may provide a new means to diagnose bacterial kidney disease in asymptomatic fish and ova.The authors are with the instituto de Bioquímica, Universidad Austral de Chile, P.O. Box 567, Valdivia, Chile 相似文献
60.
Viability of spores of Bacillus cereus was totally inhibited at 85°C over 30 min by adding 0.4% (w/v) potassium sorbate with 6% (w/v) NaCl at pH 4.5. Viability of B. stearothermophilus spores was totally inhibited at 95°C for 45 min in a buffer at pH 4.2 containing 0.8% (w/v) potassium sorbate and 8% (w/v) NaCl. A synergistic inhibitory effect was demonstrated in some of the combinations. The inhibition may be due to interference with the heat-resistance apparatus of the spores.O.B. Oloyede was and J. Scholefield is with the Department of Bioscience & Biotechnology, Food Science Division, University of Strathclyde, Glasgow G1 1SD, UK. O.B. Oloyede is now with the Department of Biochemistry, University of Ilorin, Ilorin, Nigeria. 相似文献