Nanomolar Levels Of Pahs In Extracts From Urban Air Induce Mapk Signaling In Hepg2 Cells.

Polycyclic aromatic hydrocarbons (PAHs) are common environmental pollutants that occur naturally in complex mixtures. Many of the adverse health effects of PAHs including cancer are linked to the activation of intracellular stress response signaling. This study has investigated intracellular MAPK signaling in response to PAHs in extracts from urban air collected in Stockholm, Sweden and Limeira, Brazil, in comparison to BP in HepG2 cells. Nanomolar concentrations of PAHs in the extracts induced activation of MEK4 signaling with down-stream increased gene expression of several important stress response mediators. Involvement of the MEK4/JNK pathway was confirmed using siRNA and an inhibitor of JNK signaling resulting in significantly reduced MAPK signaling transactivated by the AP-1 transcription factors ATF2 and c-Jun. ATF2 was also identified as a sensitive stress responsive protein with activation observed at extract concentrations equivalent to 0.1 nM BP. We show that exposure to low levels of environmental PAH mixtures more strongly activates these signaling pathways compared to BP alone suggesting effects due to interactions. Taken together, this is the first study showing the involvement of MEK4/JNK/AP-1 pathway in regulating the intracellular stress response after exposure to nanomolar levels of PAHs in environmental mixtures.

Dispersão de sementes de Vismia cayennensis (Jacq.) Pers. (Guttiferae) por morcegos na região de Manaus, Amazonas

We studied the feeding behavior of bats and their role in the seed dispersal of Vismia cayennensis in Manaus region, Amazonas State, northern Brazil. The characteristics of the plant and its fruits fit the chiropterocory syndrome. Five species of phyllostomid bats fed on Vismia fruits: Sturnira lilium, Sturnira tildae, Artibeus concolor, Carollia perspicillata and Rhinophylla pumilio. Apparently there is a relationship between flock foraging behavior and fruit availability in early night. The feeding behavior was similar for all bat species, varying with the presentation mode of the fruits. Seed germination tests and the distributional patterns of the plants indicate that bats are the dispersers of V. cayennensis.