Concentrations of PAHs,and nitro- and methyl- derivatives associated with a size-segregated urban aerosol

Size-segregated atmospheric particles were collected in Rome, Italy, using a low-pressure impactor.Twelve sampling campaigns were conducted under different meteorological conditions over a whole year covering 155 not consecutive days. The samples were analyzed for polycyclic aromatic hydrocarbons (PAHs) and their nitro- and methyl- derivatives known for their toxicity. An assessment of the carcinogenic potency of the particles known to penetrate into lungs, liver, heart and nervous system was performed.The distribution of the classes of compounds was unimodal and centrated at 0.4 μm size fraction for PAHs and bimodal and centrated at 0.1 and 0.4 μm for methyl- and nitro- derivatives. The 18% of toxic organic compounds we analyzed was distributed into the ultrafine fraction (PM_0.1) and 76% in the fine fraction; but substituted PAH distribution in the ultrafine particles shifted toward higher values during warm periods. In July, the 50% of the total nitro-PAHs was found in PM_0.1 and an average of 42% of the total methyl-PAHs was found in the same fraction in summer and intermediate seasons.An evaluation of the potential toxicity of the measured compounds was tentatively assessed based on Potency Equivalency Factors (PEF).     

Immunotoxicity in ascidians: Antifouling compounds alternative to organotins – II. The case of Diuron and TCMS pyridine

Using short-term hemocyte cultures of the colonial ascidian Botryllus schlosseri exposed to various sublethal concentrations of Diuron (3-(3,4-diclorophenyl)-1,1-dimethylurea) and TCMS pyridine (2,3,5,6-tetrachloro-4-(metylsulphonyl)pyridine), we evaluated their immunotoxic effects through a series of cytochemical assays previously used for organotin compounds. At concentrations higher than 250 μ M and 10 μ M for Diuron and TCMS pyridine, respectively, both biocides exerted immunosuppressant effects on Botryllus hemocytes, causing i) deep changes in the cytoskeleton that irreversibly affect cell morphology and phagocytosis, ii) induction of DNA damage, iii) leakage of oxidative and hydrolytic enzymes due to membrane alteration. Unlike organotin compounds, Diuron and TCMS pyridine do not inhibit cytochrome-c-oxidase, and only TCMS pyridine triggers oxidative stress. When co-present, they exert an antagonistic interaction on cytoskeletal components.     

Conceptual Frameworks and Methods for Advancing Invasion Ecology

Invasion ecology has much advanced since its early beginnings. Nevertheless, explanation, prediction, and management of biological invasions remain difficult. We argue that progress in invasion research can be accelerated by, first, pointing out difficulties this field is currently facing and, second, looking for measures to overcome them. We see basic and applied research in invasion ecology confronted with difficulties arising from (A) societal issues, e.g., disparate perceptions of invasive species; (B) the peculiarity of the invasion process, e.g., its complexity and context dependency; and (C) the scientific methodology, e.g., imprecise hypotheses. To overcome these difficulties, we propose three key measures: (1) a checklist for definitions to encourage explicit definitions; (2) implementation of a hierarchy of hypotheses (HoH), where general hypotheses branch into specific and precisely testable hypotheses; and (3) platforms for improved communication. These measures may significantly increase conceptual clarity and enhance communication, thus advancing invasion ecology.