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The metabolism and mutagenic activation of 2-acetylaminofluorene by human and rat hepatocytes and kidney cells were measured. High performance liquid chromatography was used to separate the 2-acetylaminofluorene metabolites, and a cell-mediated Salmonella typhimurium mutagenesis assay was used to detect mutagenic intermediates. Rat and human differences were observed with cells from both organs and levels of metabolism and mutagenesis were higher in human cells. Within a species, liver and kidney cell differences were also evident, with levels of hepatocyte-mediated metabolism and mutagenesis being greater than kidney cells. Human inter-individual variation was apparent with cells from both organs, but the variation observed was significantly greater in hepatocytes than kidney cells. A knowledge of such differences, including an understanding that they may vary with the chemical being studied, should be useful in the extrapolation of rodent carcinogenesis data to humans.Abbreviations AAF
2-acetylaminofluorene
- AF
2-aminofluorene
- DMSO
dimethylsulfoxide
- HPLC
high performance liquid chromatography
- N-OH-AAF
N-hydroxy-2-acetylaminofluorene
- 1-OH-AAF
1-hydroxy-2-acetylaminofluorene
- 3-OH-AAF
3-hydroxy-2-acetylaminofluorene
- 5/9-OH-AAF
a combination of 5 and 9-hydroxy-2-acetylaminofluorene
- 7-OH-AAF
7-hydroxy-2-acetylaminofluorene
- 8-OH-AAF
8-hydroxy-2-acetylaminofluorene 相似文献
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Reconstitution of a surface transferrin binding complex in insect form Trypanosoma brucei. 总被引:9,自引:1,他引:8 下载免费PDF全文
M J Ligtenberg W Bitter R Kieft D Steverding H Janssen J Calafat P Borst 《The EMBO journal》1994,13(11):2565-2573
In the bloodstream of the mammalian host, Trypanosoma brucei takes up host transferrin by means of a high-affinity uptake system, presumably a transferrin receptor. Transferrin-binding activity is seen in the flagellar pocket and is absent in insect form trypanosomes. By transfection we have reconstituted a transferrin-binding complex in insect form trypanosomes. Formation of this complex requires the products of two genes that are part of a variant surface glycoprotein expression site, expression site-associated gene (ESAG) 6 (encoding a protein with GPI-anchor) and ESAG 7 (encoding a protein without any obvious membrane attachment). This complex can be precipitated by transferrin-Sepharose and by an antibody directed only against the ESAG 6 protein. Transfection of ESAG 6 or 7 alone did not result in transferrin binding. In the transfected trypanosomes, the products of ESAG 6 alone and the combination of ESAG 6 and 7 did not exclusively localize to the flagellar pocket, but were present all over the surface of the trypanosome. The reconstituted transferrin-binding complex also did not result in the uptake of transferrin. Additional proteins present in bloodstream trypanosomes, but not in sufficient amounts in insect form trypanosomes, may therefore be required for the correct routing of the transferrin-binding complex to the flagellar pocket, and for its rapid internalization after ligand binding. 相似文献
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Growth and attachment rates of Thermothrix thiopara on calcite and pyrite were quantitated in a thiosulfate‐limited chemostat and in the thermal spring where the organism is found in nature. Surface growth rates were quantitated by using the surface colonization and exponential growth equations. These two models were compared as means of determining surface growth rates. In the chemostat, T. thiopara cells colonizing calcite and pyrite surfaces grew at approximately one‐third the rate of suspended cells. However, T. thiopara attached to pyrite faster than to calcite. In the thermal spring, growth and attachment rates were equal on calcite and pyrite. It was concluded that the exponential growth equation overestimates in‐situ surface growth rates and that T. thiopara grows more slowly when colonizing mineral surfaces than when growing in suspension. Lower growth rates on surfaces may be due to a reduced cell surface area for nutrient uptake or an increased specific maintenance rate. 相似文献
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Kieft IE Broers JL Caubet-Hilloutou V Slaaf DW Ramaekers FC Stoffels E 《Bioelectromagnetics》2004,25(5):362-368
Non-thermal plasmas can be generated by electric discharges in gases. These plasmas are reactive media, capable of superficial treatment of various materials. A novel non-thermal atmospheric plasma source (plasma needle) has been developed and tested. Plasma appears at the end of a metal pin as a submillimetre glow. We investigate the possibility of applying the plasma needle directly to living tissues; the final goal is controlled cell treatment in microsurgery. To resolve plasma effects on cells, we study cultured Chinese hamster ovarian cells (CHO-K1) as a model system. When these are exposed to the plasma, instantaneous detachment of cells from the surface and loss of cell-cell interaction is observed. This occurs in the power range 0.1-0.2 W. Cell viability is assessed using propidium iodide (PI) and cell tracker green (CTG) fluorescent staining utilizing confocal laser scanning microscopy (CLSM). Detached cells remain alive. Use of higher doses (plasma power >0.2 W) results in cell necrosis. In all cases, plasma-influenced cells are strictly localized in submillimetre areas, while no reaction in surrounding cells is observed. Due to its extreme precision, plasma treatment may be applicable in refined tissue modification. 相似文献
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The nuclear DNA of Trypanosoma brucei and other kinetoplastid flagellates contains the unusual base beta-d-glucosyl-hydroxymethyluracil, called J, replacing part of the thymine in repetitive sequences. We have described a 100 kDa protein that specifically binds to J in duplex DNA. We have now disrupted the genes for this J-binding protein (JBP) in T. brucei. The disruption does not affect growth, gene expression or the stability of some repetitive DNA sequences. Unexpectedly, however, the JBP KO trypanosomes contain only about 5% of the wild-type level of J in their DNA. Excess J, randomly introduced into T. brucei DNA by growing the cells in the presence of the J precursor 5-hydroxymethyldeoxyuridine, is lost by simple dilution as the KO trypanosomes multiply, showing that JBP does not protect J against removal. In contrast, cells containing JBP lose excess J only sluggishly. We conclude that JBP is able to activate the thymine modification enzymes to introduce additional J in regions of DNA already containing a basal level of J. We propose that JBP is a novel DNA modification maintenance protein. 相似文献
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Hepatitis C virus internal ribosome entry site (IRES) stem loop IIId contains a phylogenetically conserved GGG triplet essential for translation and IRES folding 总被引:7,自引:0,他引:7 下载免费PDF全文
Jubin R Vantuno NE Kieft JS Murray MG Doudna JA Lau JY Baroudy BM 《Journal of virology》2000,74(22):10430-10437
The hepatitis C virus (HCV) internal ribosome entry site (IRES) is a highly structured RNA element that directs cap-independent translation of the viral polyprotein. Morpholino antisense oligonucleotides directed towards stem loop IIId drastically reduced HCV IRES activity. Mutagenesis studies of this region showed that the GGG triplet (nucleotides 266 through 268) of the hexanucleotide apical loop of stem loop IIId is essential for IRES activity both in vitro and in vivo. Sequence comparison showed that apical loop nucleotides (UUGGGU) were absolutely conserved across HCV genotypes and the GGG triplet was strongly conserved among related Flavivirus and Pestivirus nontranslated regions. Chimeric IRES elements with IIId derived from GB virus B (GBV-B) in the context of the HCV IRES possess translational activity. Mutations within the IIId stem loop that abolish IRES activity also affect the RNA structure in RNase T(1)-probing studies, demonstrating the importance of correct RNA folding to IRES function. 相似文献
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