Sticky windows: chemical and biological characteristics of the organic film derived from particulate and gas-phase air contaminants found on an urban impervious surface

A novel environmentally derived mixture that integrates exposure to atmospherically derived gas- and particle-phase compounds in urban areas-namely, the organic film that develops as a thin layer on urban impervious surfaces-was investigated for its ability to induce gene expression via the aryl hydrocarbon receptor (AhR). The organic film on window glass from 21 sites in downtown Toronto (Ontario, Canada) was found to contain a complex mixture of environmental contaminants typical of urban environments, notably PAHs, n-alkanes, PCBs, organochlorine (OC) pesticides, and polar constituents. Using a stably transfected reporter cell line, we found that the crude extract of organic film induces AhR-dependent gene expression in a dose-dependent fashion. Three subfractions of the crude extract induced significant luciferase expression: nonpolar aromatic > polar aromatic > nonpolar aliphatic. Recombination of the fractions did not lead to recovery of the full activity of the crude extract, which may indicate that some of the compounds lost during fractionation were significant contributors to the induction observed with the crude extract. The interactions between a tonic dose of B[ a]P (10(-7) M) and each of the aromatic fractions were determined to be antagonistic following analysis by the method of isoboles. Our results suggest that organic film makes up a diverse array of compounds active at the AhR and that these compounds may not interact in a strictly additive manner.

Atmospherically derived organic surface films along an urban-rural gradient

Atmospherically derived organic films have been found on an impervious surface along an urban-rural gradient in the Toronto, Ontario, Canada area. Film thickness and concentrations, expressed on an aerial basis, of sigman-alkanes, sigmaPCB, sigmaPAH, and sigmaOC (organochlorine) pesticides decrease along this gradient, coincident with lower atmospheric emissions (PCB and PAH) and less accumulation in thinner rural films (OC pesticides). For PCBs and some OC pesticides, patterns of chemical abundance also shift, indicating a "fresh" pattern near emission sources (downtown) versus aged patterns at rural locations that are indicative of atmospheric transport. Plant-derived n-alkane concentrations were greater at urban than rural sites, and we hypothesize greater urban plant wax production and erosion due to air pollution. As expected, along the urban-rural gradient the concentration of particle-phase PAH decreased more rapidly than that of gas-phase compounds, but unexpectedly the contribution of alkylated PAH increased from urban to rural locations. Distances over which concentrations decline by 63% vary from 50 km for persistent gas-phase compounds (e.g., P1,2CB) to 10-20 km for reactive gas-phase compounds (e.g., naphthalene, fluoranthene) to <5-10 km for particle-phase compounds (e.g., P6-10CB, benzo[b]fluoranthene, benzo[e]pyrene).

Benzyl isothiocyanate is the chief or sole anthelmintic in papaya seed extracts

Papaya (Carica papaya) seeds were extracted in an aqueous buffer or in organic solvents, fractionated by chromatography on silica and aliquots tested for anthelmintic activity by viability assays using Caenorhabditis elegans. For all preparations and fractions tested, anthelmintic activity and benzyl isothiocyanate content correlated positively. Aqueous extracts prepared from heat-treated seeds had no anthelmintic activity or benzyl isothiocyanate content although both appeared when these extracts were incubated with a myrosinase-containing fraction prepared from papaya seeds. A 10 h incubation of crude seed extracts at room temperature led to a decrease in anthelmintic activity and fractionated samples showed a lower benzyl isothiocyanate content relative to non-incubated controls. Benzyl thiocyanate, benzyl cyanide, and benzonitrile were not detected in any preparations and cyanogenic glucosides. which were present, could not account for the anthelmintic activity detected. Thus, our results are best explained if benzyl isothiocyanate is the predominant or sole anthelmintic agent in papaya seed extracts regardless of how seeds are extracted.

Chemical and biological profiles of sediments as indicators of sources of genotoxic contamination in Hamilton Harbour. Part I: analysis of polycyclic aromatic hydrocarbons and thia-arene compounds

Bottom sediment and suspended sediment samples from Hamilton Harbour (western Lake Ontario) and from a major tributary were profiled using polycyclic aromatic hydrocarbons (PAH) and thia-arenes as source apportionment tracers. Ratios of selected PAH and ratios of monomethyl and dimethyl/ethyl dibenzothiophenes to the parent dibenzothiophenes were calculated. Thia-arene and PAH profiles of Standard Reference Material SRM 1649 (urban dust/organics), SRM 1650 (diesel), SRM 1597 (coal tar), Hamilton coal tar and a composite Hamilton air particulate sample provided source sample data. The gas chromatography-mass spectrometry (GC-MS) chromatograms of all sample extracts were dominated by homocyclic PAH but interpretation of PAH profiles with respect to source was difficult. In contrast, thia-arene analyses revealed more distinct differences in profiles of samples collected in different areas of the harbour, including the tributary. These results indicated that areas of coal tar-contaminated sediment are potential contributors to the overall contaminant burden of sediments and suspended sediments in Hamilton Harbour. These data also indicated that contaminants related to mobile combustion sources were entering the harbour via a major tributary.

Chemical and biological profiles of sediments as indicators of sources of contamination in Hamilton Harbour. Part II: bioassay-directed fractionation using the Ames Salmonella/microsome assay

Bottom sediment and suspended sediment samples from Hamilton Harbour (western Lake Ontario) and from a major tributary were profiled using a bioassay-directed fractionation approach. Sample extracts were fractionated using an alumina/Sephadex gel clean-up procedure to afford non-polar aromatic fractions which were characterized using chemical analyses and the Ames/microsome bacterial assay in Salmonella typhimurium strains YG1025 with the addition of oxidative metabolism (S9), and YG1024 without S9. Non-polar aromatic fractions of selected samples were separated by normal phase HPLC into 1-min fractions which were subjected to bioassay analyses. The bioassays using strain YG1025+S9, a TA100-type strain, were performed to assess genotoxicity arising from the presence of polycyclic aromatic hydrocarbons (PAH). Fractions which exhibited mutagenic activity contained PAH with molecular masses of 252, 276 and 278 amu; these fractions contained over 80% of the genotoxicity attributable to PAH. Individual compounds identified using Gas Chromatography-Mass Spectrometry analyses in these active fractions included benzo[a]pyrene, indeno[cd]pyrene and dibenz[a,h]anthracene. The YG1025+S9 mutagenic activity profiles were similar for all samples. Mutagenic activity profiles generated using strain YG1024-S9, a TA98-type strain sensitive to compounds characteristic of mobile source emissions, were very different. The mutagenic activities in strain YG1024-S9 were greatest for harbour-suspended sediment samples collected from sites impacted by a major tributary. Suspended sediments collected near areas known to contain high levels of coal tar-contamination in the bottom sediments contained higher levels of genotoxic PAH than suspended sediments collected from other areas of the harbour.

Induced minisatellite germline mutations in herring gulls (Larus argentatus) living near steel mills

Despite widespread industrial release of genotoxic contaminants, little is understood of their role in inducing germline mutations in natural populations. We used multilocus DNA fingerprinting to quantify germline minisatellite mutations in families of herring gulls (Larus argentatus) in three nesting categories: (a) near cities with large steel mills operating coking ovens; (b) near cities without steel mills; and (c) in rural locations removed from point sources of contamination. Gulls nesting near integrated steel mills showed significantly higher mutation rates than gulls from rural locations (Fisher's exact, P=0.0004); urban sites without steel mills fell midway between steel and rural sites (difference from rural; Fisher's exact, P=0.19). Distance of the nesting location of herring gulls from the steel industries' coking ovens was negatively correlated with minisatellite mutation rate demonstrating significant risk for induced germline mutations in cities with steel operations (Kendall Tau; tau=0.119; P<0.0001).

Characterization of ginseng saponins using electrospray mass spectrometry and collision-induced dissociation experiments of metal-attachment ions

Electrospray mass spectrometry (ESMS) and collision-induced dissociation (CID) methodologies have been developed for the structural characterization of ginseng saponins (ginsenosides). Ginsenosides are terpene glycosides containing a triterpene core to which one to four sugars may be attached. They are neutral molecules which readily form molecular metal-attachment ions in positive ion ESMS experiments. In the presence of ammonium hydroxide intense deprotonated ions are generated. Both positive and negative ion ESMS experiments were found to be useful for molecular mass and structure determination of ten ginsenoside standards. Negative ion experiments made possible the determination of the molecular mass of each ginsenoside standard, the mass of the triterpene core and the masses and sequences of the sugar residues. Positive ion ESMS experiments with the alkali metal cations Li+ or Na+ and the transition metal cations Co2+, Ni2+ and Zn2+ were also useful in determining molecular masses. These alkali and transition metal cations form strongly bonded attachment ions with the ginsenosides. As a result, the CID mass spectra of the metal attachment ions show a variety of (structure characteristic) fragmentations. These experiments can be used to determine the identity of the triterpene core, the types and attachment points of sugars to the core and the nature of the O-glycosidic linkages in the appended disaccharides. Combining the results from the negative and positive ion experiments provides a promising approach to the structure analysis of this class of natural products.

Structural analysis of diols by electrospray mass spectrometry on boric acid complexes

A method is presented to characterize diols using negative ion electrospray (ES) mass spectrometry in combination with collision-induced dissociation tandem mass spectrometry (MS/MS). The analyte diol is added to a solution containing an ethylene glycol/boric acid [2:1] complex and then subjected to infusion ES. The following boric acid complexes are formed: (i) a complex with two ethylene glycol molecules, (ii) a mixed ethylene glycol/analyte complex, and (iii) a complex with two analyte molecules. The first complex serves as a reference for the assessment of the extent of complex formation with the analyte. The ES mass spectra of acyclic vicinal diols all feature intense mixed complex signals, indicative of efficient complex formation. Chemical fine tuning is achieved by MS/MS experiments. Thus, although the (2R,3R)-(-)-2,3-butanediol and meso-2,3-butanediol stereo-isomers show the same complexation efficiency, MS/MS experiments reveal pronounced structure characteristic differences. By contrast, 1,3- and 1,4-diols are less prone to complex formation as they give only weak signals relative to the reference. For cyclic vicinal diols only the cis isomer produces an intense mixed complex, whose MS/MS spectrum is characteristically different from that of the trans form. The above procedure does not permit an unambiguous differentiation of acyclic polyhydroxy compounds like mannitol and sorbitol. However, structurally related methyl glycosides show characteristic MS/MS spectra. Our findings indicate that the above simple procedure may be useful to probe the presence and structure of diols and other polyols in aqueous solutions. Copyright 1999 John Wiley & Sons, Ltd.

Analysis of high-molecular-mass polycyclic aromatic hydrocarbons in environmental samples using liquid chromatography-atmospheric pressure chemical ionization mass spectrometry

Polycyclic aromatic hydrocarbons (PAHs) with molecular masses higher than 300 u were analysed using LC-atmospheric pressure chemical ionization (APCI) MS in extracts of environmental samples from Hamilton, Canada including zebra mussels from Hamilton Harbour, air particulate and coal tar. The LC-APCI-MS profiles of three molecular mass classes of PAHs (326 u, 350 u and 374 u) were compared to identify potential sources of PAH contamination in Hamilton Harbour. The Hamilton air particulate profile was also compared with an urban air reference standard (NIST SRM 1649) from Washington, DC, USA. Profiles of all extracts were similar and suggested an environmental predominance of PAHs within the three isomeric molecular mass classes studied. However, PAHs of molecular mass 326 u and 350 u were detected in extracts of coal tar and zebra mussels from Hamilton Harbour but were not detected in Hamilton air. These results indicated that some high-molecular-mass PAHs may be characteristic of contamination by coal tar.

Bioassay-directed fractionation of PAH of molecular mass 302 in coal tar-contaminated sediment

Bioassay-directed fractionation was used to characterise genotoxic polycyclic aromatic hydrocarbons (PAH) of molecular mass 302 amu in organic solvent extracts of coal tar-contaminated sediment from Sydney Harbour, Nova Scotia. A normal phase HPLC technique was employed to separate PAH-rich solvent extracts into fractions containing PAH of single molecular mass classes. The 302 amu molecular mass fraction was isolated and further separated using reversed phase HPLC; subfractions were collected every 30 s and subjected to bioassay analyses with Salmonella typhimurium strain YG1025 with the addition of oxidative metabolism (4% S9). Compounds eluting in the most active subfractions included naphtho[2,1-alpha]pyrene and naphtho[2,3-alpha]pyrene. The results of this study underscore the significant contribution that molecular mass 302 PAH make to the biological activity of complex environmental mixtures.

The Synthesis, NMR Spectroscopy, and X-ray Structure of a New Rhenium N(2)S(2) Chelate Complex

A new chelate, mercaptoacetyl-L-histidinyl-S-benzyl-L-cysteine methyl ester was synthesized by standard peptide coupling techniques and reacted with ReOCl(3)(PPh(3))(2) to give two diastereomers, 7a and 7b. The two isomers were separated by reversed-phase HPLC and characterized by NMR spectroscopy and electrospray mass spectrometry. An X-ray structure of one isomer, 7a, confirmed that the chelated complex was analogous to other Re-N(2)S(2) compounds in that it formed a square pyramidal complex where the four donor atoms were the base of the pyramid and the oxygen attached to the rhenium was at the apex. The S-benzyl group, as expected, was cleaved during the formation of 7, and the resulting complex was a zwitterion where the rhenium was formally -1 and the counterion was the protonated imidazole ring.

Covalent affinity labeling of brain catecholamine-absorbing proteins using a high-specific-activity substituted tetrahydronaphthalene

The recently described catecholamine-absorbing proteins (CATNAPs) are expressed within the CNS and have been shown to participate in neurochemical processes involving dopamine and several structurally related catecholamines. Specifically, CATNAPs have been implicated in participating directly in oxidative mechanisms involving reactive species (such as free radicals) derived from these compounds. Toxic free radicals generated from endogenous catecholamines have been identified as a major cause of neuronal tissue injury and are implicated in several disease processes. CATNAPs were first identified by their ability to react covalently with tritiated dopaminergic compounds, incorporating low levels of radioactivity under appropriate reaction conditions. The biochemical characterization of CATNAPs has until now been hampered by the lack of a suitable high-specific-activity probe to allow the rapid detection of these proteins. We describe here the synthesis and labeling characteristics of a high-specific-activity substituted tetrahydronaphthalene derivative (6-hydroxy-[125I]iodo-[N-(N-2',4'- dinitrophenyl)aminopropyl]-2-amino-1,2,3,4-tetrahydronaphthalene), which covalently incorporates into CATNAPs with the same tissue distribution, molecular weight patterns, and pharmacology as observed for the previously studied tritiated catecholamines. This compound greatly enhances the detection of CATNAPs and will facilitate further biochemical characterization of these proteins.

Identification of novel catecholamine absorbing proteins in the central nervous system

Several pharmacologically active catecholamines have been shown to react covalently with CNS proteins, namely species of 47, 40, 22, and 20 kDa. Of these, the 47-kDa protein showed the greatest incorporation of tritium following treatment with [3H]dopamine, [3H]ADTN, or [3H]N-propyl-norapomorphine. Labeling was accomplished by incubating the tritiated ligands with crude membrane preparations in the absence of reducing agents. These proteins displayed several unique characteristics: 1. The proteins are distributed throughout the CNS, but no evidence was found for their presence in other tissues; 2. The proteins have a unique pharmacological profile, interacting with dopamine, ADTN, N-propyl-norapomorphine, and apomorphine, but not with ligands specific for other proteins known to interact with these compounds; 3. The labeling of these proteins is not inhibited by several similar catecholamines and other catechols, suggesting specific structural requirements; and 4. These proteins exhibited stereoselectivity with respect to this labeling. These results demonstrate the existence of novel CNS proteins capable of covalently absorbing several physiologically important catecholamines in vitro.

Chemico/biological investigation of contaminated sediment from the Hamilton Harbour area of western Lake Ontario

Highly contaminated sediment from the Hamilton Harbour area of western Lake Ontario was examined using a bioassay-directed fractionation methodology. A sediment sample was extracted using a Soxhlet apparatus and the resulting extract was fractionated into compound classes using an alumina clean-up step and high performance liquid chromatographic techniques. The resulting fractions were subjected to bioassays using TA98- and TA100-like strains modified by the inclusion of genes for the activating enzymes nitroreductase and O-acetyl-transferase. The majority of the mutagenic activity displayed by the sample extract was found to be present in the fraction containing the polycyclic aromatic hydrocarbons (PAH). Extracts of the PAH-containing fraction displayed dramatically higher responses with the TA100 type strains with metabolic activation. Further separation of the PAH-containing fraction showed the majority of the biological activity coeluted with PAH having molecular masses of 276, 278, and 302 amu.

Metabolic activation of 3-nitroperylene in the Salmonella/S9 assay

The mutagenicity of 3-nitroperylene (nitroPer), a nitrated polycyclic aromatic hydrocarbon (PAH) has been extensively studied using the Ames Salmonella test. In accord with previous work, nitroPer proved to be a potent frameshift mutagen which requires activation by mixed function oxidases (MFOs) in the microsomes of rat liver S9 preparations. The concentration of S9 required for optimal activation of this mutagen is several times lower than that recommended for routine screening by the Ames test. Studies with the MFO inducers Aroclor 1254, phenobarbital, 3-methylcholanthrene and beta-naphthoflavone, as well as with some MFO inhibitors indicate that both P450b and P450c appear to be involved in the activation of nitroPer. Two non-mutagenic PAHs (perylene and benzo[e]pyrene) inhibited the mutagenicity of nitroPer in a competitive fashion. The mutagenic activity of nitroPer was greatly decreased in a strain of bacteria (TA98/1,8-DNP6) that lacks an acetyltransferase needed for the activation of many nitroarenes. Incubation of nitroPer with microsomes from Aroclor-treated rats plus appropriate cofactors led to the formation of several metabolites which could be separated from one another and from nitroPer by h.p.l.c. Three of these were direct-acting mutagens with Salmonella typhimurium strain TA98, while another required microsomal activation. We postulate that the metabolic activation of nitroPer requires three steps: (i) metabolism by MOF enzymes to yield a ring-oxidized compound which is absorbed by the bacteria; (ii) reduction of this compound to the hydroxylamine by a bacterial nitroreductase; and (iii) O-acetylation of the hydroxylamine to yield a reactive ultimate mutagen.

Identification of the DNA adduct formed by metabolism of 1,8-dinitropyrene in Salmonella typhimurium

The incubation of [3H]1,8-dinitropyrene with Salmonella typhimurium TA98NR followed by isolation of the DNA from these cells, hydrolysis of the DNA to nucleosides, butanol extraction of the hydrolysate and purification by reversed-phase liquid chromatography afforded a single product. Calf thymus DNA, after treatment with N-hydroxyl-1-amino-8-nitro-pyrene, was hydrolyzed, extracted and purified in a similar fashion to give a single compound which was shown to be the deoxyguanosine derivative 1-N-(2'-deoxyguanosin-8-yl)-amino-8-nitropyrene by a combination of proton n.m.r. and u.v.-vis. spectroscopy and fast atom bombardment mass spectrometry. The DNA adducts formed in vivo and in vitro exhibited identical chromatographic and chemical behavior. Under acidic or basic conditions in the vivo and in vitro adducts were converted to identical products. Reduction of the adduct gave a new, highly fluorescent product that had a fluorescence emission spectrum identical to that of 1,8-diaminopyrene.

Metabolism of 1,8-dinitropyrene by Salmonella typhimurium

Earlier work has shown that many nitroaromatic and nitroheterocyclic compounds are directly 'activated' to their ultimate mutagenic forms through the action of bacterial nitroreductase enzymes. However, in the case of 1,8-dinitropyrene (DNP) and certain other nitroarenes the pathway of activation is more complex and neither the identity of the ultimate mutagens nor the nature of the DNA adducts formed are known. We now show that Salmonella typhimurium strains TA98 and TA1538, which are sensitive to DNP and have wild type nitroreductase complements, do metabolize DNP to 1-amino-8-nitropyrene (ANP) and 1,8- diaminopyrene (DAP) but that these compounds are much weaker mutagens than DNP. These two strains (TA98 and TA1538) contain two separable components of nitroreductase activity as determined using nitrofurazone as the substrate. The major component, at least, is capable of reducing both 1-nitropyrene (NP) and DNP although the rates are much lower than with nitrofurazone. TA98NR , a mutant of TA98 that is resistant to nitrofurazone and NP but not to DNP, lacked the major nitroreductase but retained two minor components. In contrast, a mutant ( DNP6 ) which is resistant to DNP (but not to NP) contained a full complement of nitroreductases. When the metabolism of [3H]DNP by crude extracts of TA98 was re-examined, previously undetected metabolites were found. These were more polar than DAP and ANP and were also seen when TA98NR was used as the source of enzyme. These metabolites were not formed when enzymes from TA98DNP6 or TA98NR / DNP6 were used. This work supports the notion that some enzymic activity other than (or in addition to) nitroreductase is required for the activation of DNP and that the new polar metabolites may be related to this process.

The 1-nitropyrene reductase of Salmonella typhimurium

We have devised a sensitive fluorimetric assay to monitor the conversion of 1-nitropyrene to 1-aminopyrene. Application of this assay to extracts of Salmonella typhimurium strains TA98 and TA100 (which are sensitive to the mutagenic and lethal effects of 1-nitropyrene) has shown that these bacteria contain 'nitropyrene reductase' activity at the low level of 10(-11) mol/min/mg protein. NADPH and NADH serve equally well as reducing agents. The nitropyrene reductase activity of strain TA100 F50 (a mutant resistant to 1-nitropyrene) was found to be considerably lower.

Metabolism of 1-nitropyrene and formation of DNA adducts in Salmonella typhimurium

1-Nitropyrene is slowly reduced by intact cells of Salmonella typhimurium to yield 1-aminopyrene and N-acetyl-1-aminopyrene plus six unidentified minor products. When the bacteria are exposed to tritiated 1-nitropyrene, increasing amounts of radioactivity become bound to DNA as the nitropyrene is metabolized. Enzymatic hydrolysis of the labelled DNA yields low molecular weight labelled compounds which probably represent nucleoside adducts formed by the reaction of nitropyrene metabolites with DNA. Results with appropriate mutant strains indicate that bacterial nitroreductases are involved in activating nitropyrene to a reactive intermediate that binds to DNA and that nitropyrene adducts in DNA are subject to excision repair.