The methods for detecting carcinogens and mutagens with the Salmonella mutagenicity test were described previously (Ames et al., 1975b). The present paper is a revision of the methods. Two new tester strains, a frameshift strain (TA97) and a strain carrying an ochre mutation on a multicopy plasmid (TA102), are added to the standard tester set. TA97 replaces TA1537. TA1535 and TA1538 are removed from the recommended set but can be retained at the option of the investigator. TA98 and TA100 are retained. We discuss other special purpose strains and present some minor changes in procedure, principally in the growth, storage, and preservation of the tester strains. Two substitutions are made in diagnostic mutagens to eliminate MNNG and 9-aminoacridine. Some test modifications are discussed.

Revised methods for the salmonella mutagenicity test

Graphene quantum dots (GQDs) have various alluring properties and potential applications, but their large-scale applications are limited by current synthetic methods that commonly produce GQDs in small amounts. Moreover, GQDs usually exhibit polycrystalline or highly defective structures and thus poor optical properties. Here we report the gram-scale synthesis of single-crystalline GQDs by a facile molecular fusion route under mild and green hydrothermal conditions. The synthesis involves the nitration of pyrene followed by hydrothermal treatment in alkaline aqueous solutions, where alkaline species play a crucial role in tuning their size, functionalization and optical properties. The single-crystalline GQDs are bestowed with excellent optical properties such as bright excitonic fluorescence, strong excitonic absorption bands extending to the visible region, large molar extinction coefficients and long-term photostability. These high-quality GQDs can find a large array of novel applications in bioimaging, biosensing, light emitting diodes, solar cells, hydrogen production, fuel cells and supercapacitors.

/pdf/gram-scale-synthesis-of-single-crystalline-graphene-quantum-1r7399salb.pdf

Gram-scale synthesis of single-crystalline graphene quantum dots with superior optical properties

The nitrated polycyclic aromatic hydrocarbons constitute a group of chemicals of environmental concern which display a broad spectrum of mutagenic, genotoxic and carcinogenic properties. Some members of the group are the most potent direct-acting bacterial mutagens while others exhibit low levels of potencies which require metabolic activation mixtures. Bacterial mutagenicity is dependent upon reduction of the nitro function. In mammalian cell systems the genetic and genotoxic effects of these nitrated chemicals include the induction of unscheduled DNA synthesis, sister-chromatid exchanges, chromosomal aberrations, gene mutations and cell transformation. The qualitative as well as quantitative expression of these effects is dependent upon the species and tissue of origin as well as culture history of the cell which in turn determine their enzymic capabilities and the conversion of these nitroarenes to ultimate mutagens and genotoxicants. In eukaryotic cells the following bioactivation pathways have been recognized: (a) reduction of the nitro moiety, (b) ring oxidation (the nature of which is influenced by the nitro function) followed by reduction of the nitro group, and (c) ring oxidation without concomitant reduction of the nitro moiety.

Mutagenicity and genotoxicity of nitroarenes: All nitro-containing chemicals were not created equal

Representative dilution tube sampling techniques for particulate and gas phase vehicle emissions are described using Teflon filter media and XAD-2 resin. More than 90% of the total gas (C8-C18) and particulate direct acting Ames assay mutagenicity (TA 98) was found in the particulate phase. The gas and particulate phase material was fractionated by HPLC into nonpolar, moderately polar and highly polar chemical fractions. The moderately polar chemical fraction of the particulates contained more than 50% of the direct acting Ames assay mutagenicity for the total extract. The concentration of oxygenated polynuclear aromatic hydrocarbons (oxy-PAH) and nitrated PAH (nitro-PAH) identified in the moderately polar particulate fractions are given. Nitro-PAH account for most of the direct-acting (TA 98) Ames assay mutagenicity in these moderately polar fractions. Reactions and kinetic expressions for chemical conversion of PAH are presented. Chemical conversion of PAH to nitro-PAH during dilution tube sampling of particulates on Teflon filters and gases on XAD-2 resin is a minor problem (representing 10-20%, on the average, of the 1-nitropyrene found in extracts) at short (46 min) sampling times, at low sampling temperatures (42 degrees C), and in diluted exhaust containing 3 ppm NO2. Particulate emissions collected from dilution tubes on filter media appear to be representative of what is emitted in the environment as based upon a comparison of highway and laboratory studies.

/pdf/sampling-of-vehicle-emissions-for-chemical-analysis-and-2egertb4md.pdf

Sampling of vehicle emissions for chemical analysis and biological testing.

Nitroarenes are postulated to play a principal part among mutagens/carcinogens which are induced in the combustion process and, in addition, are widely distributed in the environment. This review deals with the following points concerning nitroarene toxicity. Data on the mutagenicity of nitroarenes obtained by short-term bioassays are expected to provide us with sufficient information for us to determine their genotoxicity and carcinogenicity. Therefore, mutagenicity detected with Salmonella, Escherichia, and yeast test systems is discussed. Genotoxicity in mammalian cells is also important for determining the mutagenic properties of nitroarenes. In this article, mutagenicity in Chinese hamster ovary cells, sister chromatid exchanges, and cell transformation is summarized. The metabolism of nitroarenes in vivo and in vitro is of importance for determining their behavior and active forms. Therefore, current studies regarding metabolism of nitroarenes are described. Carcinogenicity of nitroarenes for animals has been reported by many workers. In this review, the incidence and histological features of tumors induced by nitroarenes are described. Furthermore, the possible association between human lung cancer and nitroarenes is discussed. Sources of nitroarenes in the environment are given. The results of various chemical tests for identifying nitroarenes are summarized, and speculation on the risk of nitroarenes for humans is presented.

Mutagenicity and Carcinogenicity of Nitroarenes and Their Sources in the Environment

Extracts of selected xerographic toners and copies were found to be mutagenic in the Salmonella assay. The activity was independent of the xerographic hardware and process and was traced to nitropyrenes present as impurities in the carbon black, the toner colorant. Manufacturing process changes resulted in a substantial reduction of the nitropyrene content of the carbon black and thus in the mutagenicity of the corresponding toners. Nitropyrenes are potent frameshift mutagens, and possible mechanisms for their biological action are discussed.

http://science.sciencemag.org/content/sci/209/4460/1039.full.pdf

Nitropyrenes: isolation, identificaton, and reduction of mutagenic impurities in carbon black and toners.

Nitropyrenes cause frameshift mutations in Salmonella typhimurium . This activity which is restricted to frameshift mutations is unusual in several respects: (a) Nitropyrenes, as a class, are the most mutagenic chemicals reported in the literature; (b) The mutagenicity depends upon the formation of adducts between DNA and nitropyrene metabolites; (c) The penultimate intermediates responsible for mutagenic activity (hydroxylamines) are not obtained in all instances by reduction of the nitro function by the “classical” nitroreductase (the one that acts on nitrofurans and other simple nitrated polycyclic aromatic hydrocarbons) but by another nitroreductase which appears to be specific for higher nitrated polycyclic aromatic hydrocarbons; (d) The mutagenicity of nitropyrenes is enhanced when resting rather than growing bacterial cultures are used.

The extraordinary mutagenicity of nitropyrenes in bacteria.

An apparatus for the mixing of toner and a material to form a toner mixture is provided. The apparatus includes a grinder having a grinding chamber within the grinder and a material adder for adding the material into the grinding chamber. The apparatus further includes a mixer for mixing the toner and the material within the grinding chamber to form the toner mixture.

Injection blending of toner during grinding

Compositional analysis of 2,6-dimethyl-1,4-phenylene oxide (PPO) and styrene homopolymer blends was accomplished using infrared spectrometry and pyrolysis gas chromatography. In infrared measurements the 1030/700 cm−1 absorption ratio provides percent PPO in the blends within ±3% of the actual value but with a σ% of ±10. In pyrolysis GC measurements, four peaks resulting from the fragmentation of the PPO molecule have been investigated for quantitation. One of these peaks provides results with ±2% of the PPO present with a σ% of 7 when the percent PPO in the blend is above 20.

Compositional determination of 2,6-dimethyl-1,4-phenylene oxide and styreen hompolymer blends by infrared spectrometry and pyrolysis gas chromatography

Marsha A. Butler

Papers

Nitropyrenes: isolation, identificaton, and reduction of mutagenic impurities in carbon black and toners.

The extraordinary mutagenicity of nitropyrenes in bacteria.

Injection blending of toner during grinding

Compositional determination of 2,6-dimethyl-1,4-phenylene oxide and styreen hompolymer blends by infrared spectrometry and pyrolysis gas chromatography