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1.
The metabolism of the polycyclic aromatic hydrocarbon (PAH) carcinogen benzo[a]pyrene (BaP) was studied using microsomes prepared from the skin of the mouse and rat. Topical application of the polychlorinated biphenyl (PCB) Aroclor 1254 or the PAH 3-methylcholanthrene (3-MC) to the skin of the C57BL/6N and DBA/2N mouse and the Sprague-Dawley rat caused statistically significant enhancement of cutaneous microsomal aryl hydrocarbon hydroxylase (AHH) activity in each animal. PCB was a more potent inducer of the enzyme than was 3-MC. BaP metabolism by skin microsomes from the same animals was assessed using high performance liquid chromatography (HPLC). The skin of untreated animals metabolized BaP into 9,10-, 7,8- and 4,5-dihydrodiols, phenols and quinones. Skin application of PCB caused greater than 16–18-fold enhancement of BaP metabolism in the C57BL/6N mouse and the rat and 2–5-fold enhancement in the DBA/2N mouse. Skin application of 3-MC enhanced BaP metabolism 2–8-fold in the C57BL/6N mouse and 5–10-fold in the rat and had no effect in the DBA/2N mouse. The formation of procarcinogenic metabolite BaP-7, 8-diol was greatly enhanced (4–12-fold) by treatment with the PCB and 3-MC in the tumor susceptible C57BL/6N mouse and in the tumor-resistant neonatal Sprague-Dawley rat. In contrast, the formation of BaP-7,8-diol was either slightly enhanced (2-fold) or unaffected by treatment with the PCB or 3-MC in the tumor-resistant DBA/2N mouse. Our data indicate that neither the patterns of metabolism nor the amount of BaP-7,8-diol formation in the skin are reliable predictors of tumor susceptibility to the PAH in rodent skin. 相似文献
2.
Jane Stratford Michael A. Wright Walter Reineke Heiner Mokross Jurgen Havel Christopher J. Knowles Gary K. Robinson 《Archives of microbiology》1996,165(3):213-218
Chlorobenzoates (CBA) arise as intermediates during the degradation of polychlorinated biphenyls (PCBs) and some chlorinated herbicides. Since PCBs were produced as complex mixtures, a range of mono-, di-, and possibly trichloro-substituted benzoates would be formed. Chlorobenzoate degradation has been proposed to be one of the rate-limiting steps in the overall PCB-degradation process. Three hybrid bacteria constructed to have the ability to completely mineralise 2-, 3-, or 4-monochlorobiphenyl respectively, have been studied to establish the range of mono- and diCBAs that can be utilised. The three strains were able to mineralise one or more of the following CBAs: 2-, 3-, and 4-monochlorobenzoate and 3,5-dichlorobenzoate. No utilisation of 2,3-, 2,5-, 2,6-, or 3,4-diCBA was observed, and only a low concentration (0.11 mM) of 2,4-diCBA was mineralised. When the strain with the widest substrate range (Burkholderia cepacia JHR22) was simultaneously supplied with two CBAs, one that it could utilise plus one that it was unable to utilise, inhibitory effects were observed. The utilisation of 2-CBA (2.5 mM) by this strain was inhibited by 2,3-CBA (200 M) and 3,4-CBA (50 M). Although 2,5-CBA and 2,6-CBA were not utilised as carbon sources by strain JHR22, they did not inhibit 2-CBA utilisation at the concentrations studied, whereas 2,4-CBA was co-metabolised with 2-CBA. The utilisation of 2-, 3-, and 4-chlorobiphenyl by strain JHR22 was also inhibited by the presence of 2,3- or 3,4-diCBA. We conclude that the effect of the formation of toxic intermediates is an important consideration when designing remediation strategies.Abbreviations
PCB
Polychlorinated biphenyl
-
CBA
Chlorobenzoate 相似文献
3.
Laetitia C. M. Commandeur Ralph J. May Heinrich Mokross Donna L. Bedard Walter Reineke Harrie A. J. Govers John R. Parsons 《Biodegradation》1996,7(6):435-443
In contrast to the degradation of penta-and hexachlorobiphenyls in chemostat cultures, the metabolism of PCBs by Alcaligenes sp. JB1 was shown to be restricted to PCBs with up to four chlorine substituents in resting-cell assays. Among these, the PCB congeners containing ortho chlorine substituents on both phenyl rings were found to be least degraded. Monochloro-benzoates and dichlorobenzoates were detected as metabolites. Resting cell assays with chlorobenzoates showed that JB1 could metabolize all three monochlorobenzoates and dichlorobenzoates containing only meta and para chlorine substituents, but not dichlorobenzoates possessing an ortho chlorine substituent. In enzyme activity assays, meta cleaving 2,3-dihydroxybiphenyl 1,2-dioxygenase and catechol 2,3-dioxygenase activities were constitutive, whereas benzoate dioxygenase and ortho cleaving catechol 1,2-dioxygenase activities were induced by their substrates. No activity was found for pyrocatechase II, the enzyme that is specific for chlorocatechols. The data suggest that complete mineralization of PCBs with three or more chlorine substituents by Alcaligenes sp. JB1 is unlikely.Abbreviations PCB
polychlorinated biphenyls
- CBA
chlorobenzoate
- D
di
- Tr
tri
- Te
tetra
- Pe
penta-
- H
hexa 相似文献
4.
The enantiomers of rac-2,2′-diiodobiphenyl were separated by liquid chromatography on microcrystalline triacetylcellulose. The conformational lability, a large separation factor α, and a suitable capacity factor k′(+) of this biphenyl allowed us to convert the racemate into 90% of enantiomerically pure (-)-2,2′-diiodobiphenyl and 10% of pure (+)-2,2′-diiodobiphenyl, respectively, by a series of in situ racemization-elution cycles. The much better retained (+)-enantiomer was racemized on the chromatographic column at 50°C after the less retained (-)-enantiomer has already been eluted at 8°C. © 1995 Wiley-Liss, Inc. 相似文献
5.
The growth dry weight, fatty acid weight and fatty acid composition of two clones of Thalassiosira pseudonana Hasle & Heimdal were measured under several growth conditions. Determinations of total cellular fatty acids were made using chemical ionization mass spectrometry. Both clones had the same fatty acids, dominated by C14:0, C16:0, C16:1, C16:3, C16:4, C18:4 and C20:5, though in different relative amounts. Fatty acids typically represented 5–10% the dry weight of a cell during log Phase growth and up to 22% during stationary Phase. The C16 fatty acids of both clones changed as the cultures aged, though much more markedly in the Sargasso Sea done (13–1) than in the estuarine one (3H). The C16:0 and C16:1 acids of both clones declined sharply in the dark and were replenished in the light. Cells maintained in constant illumination, but with no cell division. produced large quantities of these acids. Cells of done 13–1 treated with polychlorinated biphenyl (PCB) initially grew more slowly than control cells, weighed more, and had higher relative amounts of C16:0 and C16:1. Fatty acid studies may provide useful indicators of ecologically important energy reserves and membrane adaptations in the algae. 相似文献
6.
Prolactin modifies the prostaglandin synthesis, prolactin binding and fluidity of mouse liver membranes 总被引:1,自引:0,他引:1
J R Dave N V Brown R A Knazek 《Biochemical and biophysical research communications》1982,108(1):193-199
The objective of these studies was to determine if prolactin, known to induce its own receptors, alters the prostaglandin (PG) synthesis which could, in turn, modify the fluidity of the membrane and thus alter the functionality of prolactin receptors. Adult male C3H mice were injected subcutaneously with 100 μg of oPRL every 4 h for 0, 24 or 48 h and sacrificed 8 h after receiving the last injection. Liver 100,000 × membrane pellets were used in the measurement of these parameters. The amount of binding of prolactin to these membranes increased with the duration of injections, the values being 179 and 244% of control values after 24 and 48 h of injections, respectively. The amounts of PGF2α and PGE synthesized also increased after these injections, the values being 127 and 270% of control for PGF2α and 634 and 695% of control values for PGE after 24 and 48 h of injections, respectively. Fluorescence polarization, an index of microviscosity, was decreased by 14 and 20% after 24 and 48 h of PRL administration, respectively. Previous studies have demonstrated simultaneous in vitro effects of prostaglandin on both prolactin receptors and membrane fluidity. The current data are in agreement with those observations and suggest that prolactin may modulate its own receptor by increasing the fluidity of the membrane in which it exists by alterations within the PG cascade. Such biochemical changes may then modify existing restraints and allow the hormone receptor to assume a more functional configuration. 相似文献
7.
Metabolism of naphthalene by the biphenyl-degrading bacterium Pseudomonas paucimobilis Q1 总被引:7,自引:0,他引:7
Pseudomonas paucimobilis Q1 originally isolated as biphenyl degrading organism (Furukawa et al. 1983), was shown to grow with naphthalene. After growth with biphenyl or naphthalene the strain synthesized the same enzyme for the ring cleavage of 2,3-dihydroxybiphenyl or 1,2-dihydroxynaphthalene. The enzyme, although characterized as 2,3-dihydroxybiphenyl dioxygenase (Taira et al. 1988), exhibited considerably higher relative activity with 1,2-dihydroxynaphthalene. These results demonstrate that this enzyme can function both in the naphthalene and biphenyl degradative pathway.Abbreviations DHBP
dihydroxybiphenyl
- DHBPDO
2,3-dihydroxybiphenyl dioxygenase
- DHDHNDH
1,2-dihydroxy-1,2-dihydronaphthalene dehydrogenase
- DHN
1,2-dihydroxynaphthalene
- DHNDO
1,2-dihydroxynaphthalene dioxygenase
- HBP
cis-2-hydroxybenzalpyruvate
- HOPDA
2-hydroxy-6-oxo-6-phenylhexa-2,4-dienoate
- PCB
polychlorinated biphenyl
- 2NS
naphthalene-2-sulfonic acid 相似文献
8.
Incubation in the presence of NADPH and molecular oxygen of 14C-labeled polychlorinated biphenyls (PCBs) and two tetrachlorobiphenyl (TCB) isomers with a reconstituted system containing NADPH-cytochrome P-450 reductase and cytochrome P-450, both purified from liver microsomes of phenobarbital(PB)-pretreated rabbits, led to covalent binding of radioactive metabolites of PCBs and TCBs to the protein components of the system. A rabbit liver cytosol fraction added to the system provided more binding sites for the activated metabolites and thus increased the extent of binding markedly. The binding reaction depended absolutely on the reductase, cytochrome P-450 and NADPH, and required dilauroyl phosphatidylcholine and sodium cholate for maximal activity. A further stimulation of the binding was attained by including cytochrome b5 in the reconstituted system. Four forms of cytochrome P-450, purified from liver microsomes of PB- and 3-methylcholanthrene(MC)-treated rabbits and rats, were used to reconstitute the PCB- and TCB-metabolizing systems, and it was found that PB-inducible forms of the cytochrome from both animals were more active than those inducible by MC in catalyzing the PCB- and TCB-binding reaction. Sodium dodecyl sulfate(SDS)-polyacrylamide gel electrophoresis indicated that, in the system containing the reductase, cytochrome P-450 and cytochrome b5, PCB metabolites bound to the reductase and cytochrome P-450, but not to cytochrome b5. In the presence of the liver cytosol fraction, the binding took place to many cytosolic proteins in addition to the reductase and cytochrome P-450. 相似文献
9.
10.
A number of highly purified polychlorinated biphenyl (PCB) isomers and congeners were synthesized and administered to male Wistar rats at dosage levels of 30 and 150 μmol · kg−1. The effects of this in vivo treatment on the drug-metabolizing enzymes were determined by measuring the microsomal benzo[a]pyrene (B[a]P) hydroxylase, dimethylaminoantipyrine (DMAP) N-demethylase and NADPH-cytochrome c reductase enzyme activities, the cytochrome b5 content and the relative peak intensities and spectral shifts of the reduced microsomal cytochrome P-450: CO and ethylisocyanide (EIC) binding difference spectra. The results were compared to the effects of administering phenobarbitone (PB), 3-methylcholanthrene (MC) and PB plus MC (coadministered) to the test animals. The synthetic PCB congeners used in this study included 3,4,4′,5-tetrachlorobiphenyl (TCBP-1), 2,3′,4,4′-tetrachlorobiphenyl (TCBP-2), 2,3′,4,4′,5′-pentachlorobiphenyl (PCBP-1), 2,3,4,4′,5-pentachlorobiphenyl (PCBP-2), 2,3,3′,4,4′,5-hexachlorobiphenyl (HCBP-1), 2,3,3′,4′,5,6-hexachlorobiphenyl (HCBP-2), 2,3,3′,5,5′,6-hexachlorobiphenyl (HCBP-3), 2,2′,3,5,5′,6-hexachlorobiphenyl (HCBP-4) and 2,3,3′,4,5,5′-hexachlorobiphenyl (HCBP-5) and were used to reappraise the structure-activity rules for PCBs as hepatic microsomal enzyme inducers. The results suggested that (a) PCBs which induce MC or mixed-type activity must be substituted at both para positions, at least two meta positions but not necessarily on the same phenyl ring and can also contain one ortho chloro substituent; (b) due to the considerable structural diversity of the PB-type inducers the rules for induction of this activity by PCB congeners are not readily defined. 相似文献