Mouse strain differences in the induction of micronuclei by polycyclic aromatic hydrocarbons

The frequency of micronucleated erythrocytes (MNE) in 3 inbred mouse strains and 2 of their hybrids (C57BL/6, BALB/c, DBA/2, BDF1 and CDF1) were examined after polycyclic aromatic hydrocarbons (PAHs; 7,12-dimethylbenz[a]anthracene (DMBA), 3-methylcholanthrene (3-MC), benzo[a]pyrene (BaP), benzo[e]pyrene (BeP) and anthracene (ANT] were injected i.p. PAHs are thought to form active metabolites after being administered to mammals. In mouse strains with inducible PAH activating enzymes, such as C57BL/6 or BALB/c, MNE were significantly induced, as compared to control mice, 48 h after DMBA, BaP, or 3-MC was injected. No increase in the frequency of MNE occurred in the DBA/2 strain which cannot induce the activating enzymes. BeP and ANT did not increase the frequency of MNE in any mouse used. The levels of MNE induction in BDF1 or CDF1 hybrids were similar to those in C57BL/6 or BALB/c. These results support the view that the genetic capacity to metabolize PAHs is strongly associated with micronucleus induction as in the case of PAH carcinogenesis.     

Reaction of solid carrier-adsorbed polycyclic aromatic hydrocarbons with gaseous low-concentrated nitrogen dioxide

The interaction of gaseous NO2 with solid carrier-adsorbed polycyclic aromatic hydrocarbons was studied under laboratory conditions with a specific attention to factors that might possibly influence this reaction, such as type of carrier lighting conditions, NO2 concentration, exposure time, and temperature. At the NO2 concentration of 1.33 ppm there were detected the following nitro derivatives: nitroanthracene, nitropyrene, nitrochrysene, two mononitro derivatives of benzo/a/pyrene, and dinitrobenzo/a/pyrene. The experimental data suggest that the formation of nitroaromates in atmospheric environment is to be expected, provided that there are present, besides polycyclic aromatic hydrocarbons and nitrogen oxides, also suitable types of sorbents, such as silica gel or fly ash.     

DNA adducts formation and induction of apoptosis in rat liver epithelial 'stem-like' cells exposed to carcinogenic polycyclic aromatic hydrocarbons

The bipotent liver progenitor cells, so called oval cells, may participate at the early stages of hepatocarcinogenesis induced by chemical carcinogens. Unlike in mature parenchymal cells, little is known about formation of DNA adducts and other genotoxic events in oval cells. In the present study, we employed spontaneously immortalized rat liver WB-F344 cell line, which is an established in vitro model of oval cells, in order to study genotoxic effects of selected carcinogenic polycyclic aromatic hydrocarbons (PAHs). With exception of dibenzo[a,l]pyrene, and partly also benzo[g]chrysene and benz[a]anthracene, all other PAHs under the study induced high levels of CYP1A1 and CYP1B1 mRNA. In contrast, we observed distinct genotoxic and cytotoxic potencies of PAHs. Dibenzo[a,l]pyrene, and to a lesser extent also benzo[a]pyrene, benzo[g]chrysene and dibenzo[a,e]pyrene, formed high levels of DNA adducts. This was accompanied with accumulation of Ser-15 phosphorylated form of p53 protein and induction of apoptosis. Contrary to that, benz[a]anthracene, chrysene, benzo[b]fluoranthene and dibenzo[a,h]anthracene induced only low amounts of DNA adducts formation and minimal apoptosis, without exerting significant effects on p53 phosphorylation. Finally, we studied effects of 2,4,3',5'-tetramethoxystilbene and fluoranthene, inhibitors of CYP1B1 activity, which plays a central role in metabolic activation of dibenzo[a,l]pyrene. In a dose-dependent manner, both compounds inhibited apoptosis induced by dibenzo[a,l]pyrene, suggesting that it interferes with the metabolic activation of the latter one. The present data show that in model cell line sharing phenotypic properties with oval cells, PAHs can be efficiently metabolized to form ultimate genotoxic metabolites. Liver progenitor cells could be thus susceptible to this type of genotoxic insult, which makes WB-F344 cell line a useful tool for studies of genotoxic effects of organic contaminants in liver cells. Our results also suggest that, unlike in mature hepatocytes, CYP1B1 might be a primary enzyme responsible for formation of DNA adducts in liver progenitor cells.     

In vitro effects of certain polycyclic aromatic hydrocarbons on mitogen activation of mouse T-lymphocytes: action of histamine

T lymphocytes were isolated from the spleens, thymuses, and bone marrow of three inbred mice strains, and the effects of two carcinogenic polycyclic aromatic hydrocarbons (PAH) on the mitogen activation of these cells were assessed. Benzanthracene (BA) and 3-methylcholanthrene (MCA) enhanced mitogen activation of splenic T cells in a strain-related fashion: C3H greater than C57BL greater than DBA/2 (P less than 0.025). This pattern of strain relatedness was not observed in T cells from the other lymphoid organs. Mitogen activation was suppressed by histamine to a greater degree in T cells from PAH-responsive mice (C3H and C57BL) than in the nonresponsive strain (DBA/2). Histamine inhibited rosette formation between T cells and histamine-conjugated sheep red blood cells. A histamine suppressor factor (HSF), isolated from splenic lymphocytes grown in the presence of histamine or histamine plus MCA, was significantly higher in activity in culture supernatants from T cells derived from responsive mice than from nonresponsive mice. With the use of Lyt 1 and Lyt 2 monoclonal antibodies, it is shown that the baseline percentage of T helper and T suppressor cells was not significantly different in all three strains. Further, histamine and MCA had no effect on the expression of the Lyt 1 and Lyt 2 surface antigens on splenic lymphocytes. These results suggest that PAH-responsive mice may have more T-cell H2 receptors than T cells from nonresponsive mice. Histamine and PAH compounds may act on the same T-cell subsets, as evidenced by the fact that BA and MCA enhance blastogenesis, histamine suppresses mitogen activation, and these PAH compounds enhance histamine and HSF activity.     

多环芳烃对植物的影响

介绍了植物体中多环芳烃(PAHs)的来源,并阐述了PAHs对植物生长的影响及植物对PAHs胁迫的生理响应。     

多环芳烃类化合物在土壤上的吸附

研究了几种多环芳烃化合物在土壤上的吸附行为．通过一个连续投药－取样试验装置,在没有任何其它有机试剂干扰的情况下,测定了荧蒽与菲在土壤上的吸附量．研究表明,这两种多环芳烃化合物在土壤上的吸附量与土壤有机质含量之间呈显著相关．对多环芳烃化合物的分子结构及理化特性,如辛醇－水分配系数、溶解度等参数与ＬｏｇＫｏｃ关系的研究发现多环芳烃化合物的ＬｏｇＫｏｃ与化合物的水溶性、辛酸－水分配系数以及分子结构中的苯环数线性相关．     

Biodegradation of polycyclic aromatic hydrocarbons

The intent of this review is to provide an outline of the microbial degradation of polycyclic aromatic hydrocarbons. A catabolically diverse microbial community, consisting of bacteria, fungi and algae, metabolizes aromatic compounds. Molecular oxygen is essential for the initial hydroxylation of polycyclic aromatic hydrocarbons by microorganisms. In contrast to bacteria, filamentous fungi use hydroxylation as a prelude to detoxification rather than to catabolism and assimilation. The biochemical principles underlying the degradation of polycyclic aromatic hydrocarbons are examined in some detail. The pathways of polycyclic aromatic hydrocarbon catabolism are discussed. Studies are presented on the relationship between the chemical structure of the polycyclic aromatic hydrocarbon and the rate of polycyclic aromatic hydrocarbon biodegradation in aquatic and terrestrial ecosystems.     

Porphinatoiron-mediated oxidation of polycyclic aromatic hydrocarbons

Although porphinatoiron complexes have been used extensively as biomimetic catalysts for oxidation of aliphatic and olefinic hydrocarbons, few oxidations of polycyclic aromatic hydrocarbons (PAH) have been reported. In all cases, heterogeneous iodosobenzene/tetraphenylporphinatoiron(III) systems were employed, oxidations were inefficient and control experiments demonstrating the requirement for catalyst were not described. The current study investigates the oxidation of pyrene, benzo[a]pyrene and benzanthracene in a homogeneous m-chloroperoxybenzoic acid/bifacially hindered porphinatoiron system in which the peroxyacid was shown to be unreactive in the absence of catalyst. Pyrene and benzo[a]pyrene were oxidized efficiently, with pyrene yielding mixtures of 1.6- and 1.8-quinones and benzo[a]pyrene yielding mixtures of phenols and quinones. Benzanthracene was oxidized less efficiently, primarily at the meso positions, to give 7.12-quinone. Initial oxidation of meso carbons of benzo[a]pyrene (confirmed by the presence of the 6-hydroxy derivative as a product) and benzanthracene indicates that PAH-to-catalyst charge transfer may be an important oxidation pathway. Oxidation of pyrene was performed by addition of pyrene to observable oxo iron(V) species as well as in a catalytic reaction where excess peroxyacid was added to a solution of pyrene and catalyst and oxo iron(V) is not generated as an observable intermediate. Yields (based on oxidant consumed), were identical under both conditions, strongly supporting oxo iron(V) as a common intermediate.