Mitogen-activated protein kinases (MAPKs) are a group of cytoplasmic phosphoproteins that constitute the central core of the signalling network to respond to stress in most organisms. Their role in stress response in micro- and macroalgae is being studied by our research group in the recent years. In this study, it is demonstrated via short experiments (1 h in duration), the rapid activation of two MAPKs similar to p38 and JNK of mammalian cells, in the Arctic kelps Laminaria solidungula and Saccharina latissima exposed to temperature and UV stress. These MAPKs are highly phosphorylated in response to temperature and UV light. In S. latissima, both p38 and the JNK showed higher phosphorylation at 2° C than at 7° C, while the reverse response was shown for L. solidungula. In addition, a significant increase in phosphorylation of both kinases was found following exposure to UV radiation (UVR). Exposure to PAR + UVA + UVB induced higher phosphorylation than PAR + UVA in L. solidungula, especially at 7° C. In S. latissima, this response occurred only with JNK, and no differences in p38 phosphorylation between PAR + UVA and PAR + UVA + UVB at any temperature were observed. These results indicate the possible involvement of MAPK-like proteins in response to different kind of stress in Arctic kelps, and that their activation is species-specific. Results are discussed in the frame of global change, confronting the response of endemic Arctic species and Arctic cold-temperate species. New experiments of one week in duration and the use of specific inhibitors of MAPKs phosphorylation will allow to determine the cause-effect relationship between these phosphoproteins and survival in a warmer and higher UVR Arctic scenario.
