Effects of 50-Hz magnetic fields on the signalling pathways of fMLP-induced shape changes in invertebrate immunocytes: the activation of an alternative stress pathway

N-formyl-Meth-Leu-Phe (fMLP)-induced immunocyte shape changes in the mussel Mytilus galloprovincialis through both the phosphatidylinositol and the cAMP pathways are studied. Fifteen- and thirty-minute exposures of mussels to 50-Hz magnetic fields (MFs) at intensities of 300 and 400 muT do not provoke permanent cell damage, since immunocytes maintain the capacity to respond to fMLP. This avoidance of external insult seems to be achieved through the activation of a stress pathway which is not functionally detectable in nonexposed animals and which involves mitogen activated protein (MAP) kinase members. This phenomenon is clearly evident at 400 muT. Contemporaneously, a different expression of Jun transcriptional regulatory proteins is also found. (C) 2002 Elsevier Science B.V. All rights reserved.