Response of sedimentary bacteria in a Louisiana salt marsh to contamination by diesel fuel

In a 28 d microcosm study, we examined the effects of diesel-contaminated sediment on the sedimentary bacterial community of a Louisiana (USA) salt marsh that has been chronically exposed to petroleum hydrocarbons for decades. Diesel contaminants in microcosms as determined from polycyclic aromatic hydrocarbon (PAH) concentration ranged from 0.55 to 55 ppm (dry weight). Bacterial metabolism (incorporation of 14C-acetate and 3H-leucine) and bacterial abundance were not affected by diesel-contaminated sediment at any concentration. Bacterial degradation of 14C-phenanthrene, however, increased in direct proportion to the amount of diesel- contaminated sediment added. Ambient sediment also exhibited significant capacity to degrade PAH. The half life of phenanthrene (based on 14C-phenanthrene-degradation experiments) ranged from 137 d in ambient sediments to 4.5 d in sediment chronically exposed to high levels of diesel-contaminated sediments for 28 d. Two- and three-ring PAH, including naphthalenes, phenanthrenes, and dibenzothiophenes, constituted the bulk of PAH composition of diesel and were rapidly metabolized. Alkylated PAH were also readily metabolized. The rapid removal of PAH suggests that even if the marsh were exposed to chronically high levels of petroleum hydrocarbons, chemical evidence of the contaminants would not be detected in sediments. Collectively, these results are consistent with the hypothesis that the bacterial community in this salt marsh has adapted to chronic exposure to petroleum hydrocarbons

Development of an isotope dilution liquid chromatography/tandem mass spectrometry detection method for DNA adducts of selected aromatic amines

AbstractPolycyclic aromatic amines (arylamines) are a class of chemical carcinogens that are prevalent in environmental and industrial settings. They are metabolically activated to covalently bond to DNA, forming mutagenic adducts. In order to study the mechanisms of their toxicity, sensitive and selective quantitative LC/MS/MS detection methods were developed to measure the N-(adenin-8-yl)-benzidine adduct and N-(adenin-8-yl)-2-aminofluorene in total DNA extract samples. A novel synthetic method using a palladium catalyst was previously developed to prepare authentic and deuterated arylamine-adenine adducts to serve as standards. These standards were then used to develop an HPLC electrospray ionization tandem mass spectrometry, isotope dilution method. Sample detection limits in DNA samples were 22 pg on-column and 51 pg on-column for the N-(adenin-8-yl)-benzidine- and N-(adenin-8-yl)-2-aminofluorene-adenine adducts, respectively. This method has applications for the study of DNA adduct formation as a biological marker of exposure to carcinogens and for environmental and workplace monitoring of these aromatic amines

Development of methods for the detection of trace amounts of selected carcinogenic and mutagenic amines in water

A great deal of concern exists over the presence of potentially carcinogenic and/or mutagenic substances in drinking water supplies. The general analytical schemes currently applied to water are less suited than specific methods for the detection of certain classes of organic contaminants such as aromatic amines because of their reactivity. We have concentrated our efforts at developing analytical schemes by which we are able to reliably detect, separate, and quantitate trace levels of a number of aromatic and heterocyclic amines. Both liquid and gas chromatographic methods have been developed. The relative strengths and limitations of the methods are discussed. Field evaluations of the final methods were carried out and reported.U.S. Department of the InteriorU.S. Geological SurveyOpe

Time-Dependent Regulation of Apoptosis by Aen and Bax in Response to 2-Aminoanthracene Dietary Consumption

Background/Objective: The modulation of the toxic effects of 2-aminoanthracene (2AA) on the liver by apoptosis was investigated. Fisher-344 (F344) rats were exposed to various concentrations of 2AA for 14 and 28 days. The arylamine 2AA is an aromatic hydrocarbon employed in manufacturing chemicals, dyes, inks, and it is also a curing agent in epoxy resins and polyurethanes. 2AA has been detected in tobacco smoke and cooked foods. Methods: Analysis of total messenger ribonucleic acid (mRNA) extracts from liver for apoptosis-related gene expression changes in apoptosis enhancing nuclease (AEN), Bcl2-associated X protein (BAX), CASP3, Jun proto-oncogene (JUN), murine double minute-2 p53 binding protein homolog (MDM2), tumor protein p53 (p53), and GAPDH genes by quantitative real-time polymerase chain reaction (qRT-PCR) was coupled with terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) and caspase-3 (Casp3) activity assays. Results: Specific apoptosis staining result does not seem to show significant difference between control and treated animals. This may be due to freeze-thaw artifacts observed in the liver samples. However, there appears to be a greater level of apoptosis in medium- and high-dose (MD and HD) 2AA treated animals. Analyses of apoptosis-related genes seem to show AEN and BAX as the main targets in the induction of apoptosis in response to 2AA exposure, though p53, MDM2, and JUN may play supporting roles. Conclusion: Dose-dependent increases in mRNA expression were observed in all genes except Casp3. BAX was very highly expressed in the HD rats belonging to the 2-week exposure group. This trend was not observed in the animals treated for 4 weeks. Instead, AEN was rather very highly expressed in the liver of the MD animals that were treated with 2AA for 28 days

Sorption properties of sediments and energy-related pollutants

"Department of Agronomy, University of Illinois at Urbana-Champaign.""Environmental Processes Branch, Environmental Research Laboratory.""April 1980.""Contract no. 68-03-2555.""Institute for Environmental Studies, University of Illinois at Urbana-Champaign."Includes bibliographical references

2-AA Anthracene Pancreatic Toxicity in Fisher 344 Rats

Abstract The mutagen 2-aminoanthracene (2-AA) is an aromatic amine or arylamine, which belongs to a class of polycyclic aromatic hydrocarbons. 2-AA is used in the manufacturing of a wide variety of chemicals, drugs, dyes, and polymers. Non-occupational sources include tobacco smoking and cooked foods. The goal of this study is to evaluate pancreatic gene expression patterns in Fischer-344 (F-344) male rats exposed to 2-AA. As a first step the effects of 2-aminoanthracene exposure on the pancreas with particular interest in genes that relate to insulin and insulin metabolism. To achieve this goal, twenty-four post-weaning, 3-4 week old F-344 male rats were exposed to 0 mg/kg-diet (control), 50 mg/kg-diet (low dose), 75 mg/kg-diet (medium dose) and 100 mg/kg-diet (high dose) 2-AA for 14 and 28 days followed by analysis of the pancreas for broad gene expression changes. Results obtained from our study suggest most of the mRNA transcripts that were differentially expressed are involved in energy metabolism in the pancreas, protein digestion and some that play an active role in pancreatitis and pancreatic cancer. Some of these genes include: insulin, colipase pancreatic, carboxypeptidase, chymotrypsinogen B1 and chymotrypsin C (caldecrin). Quantitative PCR determination of fold changes in selected genes show similar trends to global expression determined via microarray analyses

Profile of Six Hepatic Insulin Signaling Pathway Genes in Response to 2-Aminoanthracene Dietary Ingestion

Six genes that regulate various processes in the insulin signaling pathway were profiled. These transcripts were reported to regulate other genes that are essential for glucose metabolism, fatty acid and lipid biosynthesis. In a previous he-patic global gene expression analysis followed by DAVID bioinformatics analytics showed ampk, g6pc, gck, pp1, srebp-1C and socs2 to be likely modulated by 2-aminoanthracene (2AA) dietary consumption. The goal of the current study is to evaluate the responses of these proteins in the liver of Fisher-344 (F344) rats exposed to 2AA. 2AA belongs to a class of compounds referred to as polycyclic aromatic hydrocarbons (PAHs). This compound has been detected in broiled food and tobacco smoke. F344 rats were fed 2AA adulterated diets of 0 mg/kg, 50 mg/kg, 75 mg/kg and 100 mg/kg for 14- and 28-days. Differential gene expression of ampk (Prkab1), g6pc, gck, pp1, srebp-1C, socs2 and gapdh were be carried out by qRT-PCR. Results seem to suggest 2AA modulates different genes related to energy metabolism in the liver. Relative quantification of these products indicated an up-regulation of the ampk and socs in animals treated to 100 mg/kg-diet and 50 mg/kg-diet respectively during 14 days of feeding. The rest of the mRNA transcripts were down-regulated in the treated rats relative to the control group. G6pc gene was highly up-regulated in all animals that ingested 2AA for 28 days. Pp1 protein was also up-regulated in the 75 mg/kg-diet rats. The rest of the genes tested were not differentially altered. This result will be followed by a protein immunoblot assay to examine the expression of g6pc and ampk

Time-Dependent Regulation of Apoptosis by Aen and Bax in Response to 2-Aminoanthracene Dietary Consumption

The modulation of the toxic effects of 2AA on the liver by apoptosis was investigated. The arylamine 2-aminoanthracene (2AA) is an aromatic hydrocarbon employed in manufacturing chemicals, dyes, inks, and as curing agents in epoxy resins and polyurethanes. 2AA has been detected in tobacco smoke and cooked foods. Analysis of total mRNA extracts from liver for apoptosis-related gene expression changes was coupled with liver tissue histology (H&E staining), TUNEL and Caspase-3 activity assays. Specific apoptosis staining showed greater level of apoptosis in medium- and high-dose 2AA treated animals. Apoptosis does not seem to occur directly via caspase-3 activation mechanism. Analyses of apoptosis-related genes seem to show AEN and BAX as the main targets in the induction of apoptosis in response to 2AA exposure. Dose-dependent increases in mRNA expression were observed in all genes except caspase 3. Bax was highly expressed in the high-dose rats belonging to the 2-week exposure group

Apoptosis Modulates Hepatotoxic Effects of 2-Aminoanthracene in Fisher 344 Rat

The arylamine 2-amino-anthracene (2-AA) is an aromatic hydrocarbon employed in manufacturing of chemicals, dyes, inks, and as curing agents in epoxy resins and polyurethanes. 2-AA has been detected tobacco smoke and cooked foods. The modulation of the toxic effects of 2-AA on the liver by apoptosis was investigated on twenty four post-weaning 3-4 week old F-344 male rats exposed to 0 mg/kg-diet (control), 50 mg/kg-diet (LD), 75 mg/kg-diet (MD) and 100 mg/kg-diet (HD) 2-AA for 14 [2WK] and 28 days [4WK]. Analysis of total mRNA extracts from liver for apoptosis-related gene expression changes in AEN, BAX, CASP3, JUN, MDM2, P53, and GAPDH genes by qRT-PCR was coupled with liver tissue histology (H&E staining), TUNEL (Terminal deoxynucleotidyl transferase dUTP nick end-labeling) assay and Caspase (Caspase Glo assay) activity. Dose-related histological changes in liver cell architecture were observed at the highest doses in both 2WK and 4WK exposures. Dose-related increases in TUNEL-positive staining were also observed. Caspase3 assays showed dose-dependent increases (2WK) but suppression in LD and MD [4WK] rat livers and an increase in HD rats. Dose-related increases in expression were observed in all genes measured