Comparative extraction of genotoxic components of air particulates with several solvent systems

Bird song, ecology and speciation

The study of bird song dialects was once considered the most promising approach for investigating the role of behaviour in reproductive divergence and speciation. However, after a series of studies yielding conflicting results, research in the field slowed significantly. Recent findings, on how ecological factors may lead to divergence in both song and morphology, necessitate a re-examination. We focus primarily on species with learned song, examine conflicting results in the literature and propose some potential new directions for future studies. We believe an integrative approach, including an examination of the role of ecology in divergent selection, is essential for gaining insight into the role of song in the evolution of assortative mating. Habitat-dependent selection on both song and fitness-related characteristics can lead to parallel divergence in these traits. Song may, therefore, provide females with acoustic cues to find males that are most fit for a particular habitat. In analysing the role of song learning in reproductive divergence, we focus on post-dispersal plasticity in a conceptual framework. We argue that song learning may initially constrain reproductive divergence, while in the later stages of population divergence it may promote speciation.

Mutagenicity and carcinogenicity of nitroarenes and their sources in the environment

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.

The assessment of the mutagenic potential of vehicle engine exhaust in the Ames Salmonella assay using a direct exposure method

A method for the assessment of the mutagenic activity of vehicle engine exhaust in the Ames assay is described in which the bacterial strains used (TA98 and TA98/DNP) are exposed to the freshly produced engine exhaust using a "Cassella' slit sampler. The method is found to be effective both in the presence and absence of metabolic activation, using Aroclor-1254-induced rat liver S9 fractions. A comparison is made between the direct exposure method and the standard methods involving the collection of particulate samples on glass fibre filters and the testing of various extracts of these samples. Possible uses of the direct exposure testing method are suggested and the effect of sampling techniques on the results obtained in the Ames assay is also discussed.