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.

Characterisation Of The Membrane Transport Of Pilocarpine In Cell Suspension Cultures Of Pilocarpus Microphyllus.

Pilocarpine is an alkaloid obtained from the leaves of Pilocarpus genus, with important pharmaceutical applications. Previous reports have investigated the production of pilocarpine by Pilocarpus microphyllus cell cultures and tried to establish the alkaloid biosynthetic route. However, the site of pilocarpine accumulation inside of the cell and its exchange to the medium culture is still unknown. Therefore, the aim of this study was to determine the intracellular accumulation of pilocarpine and characterise its transport across membranes in cell suspension cultures of P. microphyllus. Histochemical analysis and toxicity assays indicated that pilocarpine is most likely stored in the vacuoles probably to avoid cell toxicity. Assays with exogenous pilocarpine supplementation to the culture medium showed that the alkaloid is promptly uptaken but it is rapidly metabolised. Treatment with specific ABC protein transporter inhibitors and substances that disturb the activity of secondary active transporters suppressed pilocarpine uptake and release suggesting that both proteins may participate in the traffic of pilocarpine to inside and outside of the cells. As bafilomicin A1, a specific V-type ATPase inhibitor, had little effect and NH4Cl (induces membrane proton gradient dissipation) had moderate effect, while cyclosporin A and nifedipine (ABC proteins inhibitors) strongly inhibited the transport of pilocarpine, it is believed that ABC proteins play a major role in the alkaloid transport across membranes but it is not the exclusive one. Kinetic studies supported these results.

Eficiência do processo de recobrimento de sementes de brócolos recobertas com polímero em leito de jorro

Broccoli seeds were coated in a conical-cylindrical spouted bed with an aqueous suspension of hydroxy ethyl cellulose aiming to improve the seeds coating technique using a fluid-dynamic process. An experimental design was applied to investigate the effects of the operating variables: gas temperature, atomizing air pressure and suspension flow rate on the germination of the seeds and on the process efficiency. Results indicated that the operating variables affect both the coating process efficiency and the germination ability. However, the analysis didn t identify differences between the germination potential of coated and uncoated seeds. Coated seeds absorbed up to 10 percent less moisture than the uncoated ones, when the environment temperature and humidity were controlled over a period of time.

Antioxidative responses of cell suspension cultures of two Coffea arabica varieties to low aluminum levels at pH 5.8

The effects of aluminum (Al) on the activities of antioxidant enzymes and ferritin expression were studied in cell suspension cultures of two varieties of Coffea arabica, Mundo Novo and Icatu, in medium with pH at 5.8. The cells were incubated with 300 µM Al3+, and the Al speciation as Al3+ was 1.45% of the mole fraction. The activities of superoxide dismutase (SOD), catalase (CAT), and glutathione S-transferase (GST) were increased in Mundo Novo, whereas glutathione reductase (GR) and guaiacol peroxidase (GPOX) activities remained unchanged. SOD, GR, and GST activities were increased in Icatu, while CAT activity was not changed, and GPOX activity decreased. The expression of two ferritin genes (CaFer1 and CaFer2) were analyzed by Real-Time PCR. Al caused a downregulation of CaFER1 expression and no changes of CaFER2 expression in both varieties. The Western blot showed no alteration in ferritin protein levels in Mundo Novo and a decrease in Icatu. The differential enzymes responses indicate that the response to Al is variety-dependent.

Risco, corpo e socialidade no voo livre

Universidade Estadual de Campinas . Faculdade de Educação Física