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With the aim of examining the response of plant cells to extremely low frequency (ELF) electromagnetic fields (EMF), we investigated the behaviour of the phosphatidylinositol 4,5 bisphosphate (PtdIns 4,5-P2) molecule (the precursor of the phosphoinositide signal transduction cascade) by exposing callus cells from Peganum harmala to 50 Hz, 1 gauss EMF for 10 min and by examining the level and the fatty acid composition of PtdIns 4,5-P2 after the exposure. Our results evidenced a statistically significant decrease in PtdIns 4,5-P2 concentrations and a different involvement of the constituting fatty acids in the induced breakdown. The manipulation of the lipid-based signalling pathway by phosphoinositide-phospholipase C (PI-PLC) inhibitors (i.e., neomycin, U-73122 and ET-18-OCH3) seems to support the hypothesis that, as in animals, also in plants, the cell membrane is the primary impact site of ELF electromagnetic stimulus and that this interaction could probably involve the activation of PI signal transduction pathway including a heterotrimeric G protein. [Copyright &y& Elsevier]

The effects of the exposure to a static magnetic field (sMF) of 0.3 ± 0.03 T on the Fusarium culmorum were investigated in vitro. sMF inhibition of mycelia growth was accompanied by morphological and biochemical changes. Fungal conidia germination and cell viability were also reduced. We provide evidence of the influence of sMF on Ca2+-dependent signal transduction pathways involved in conidia germination. Perturbation of these pathways by adding different compounds (i.e. CaCl2, phorbol 12-myristate 13-acetate, neomycin, EGTA, LiCl) to the medium, suggested that exposed conidia are unable to mobilise calcium from intracellular stores and that the hindered mechanism may be IP3-dependent. [Copyright &y& Elsevier]