Seasonal changes in proteomic profiles of Japanese kelp: Saccharina japonica (Laminariales, Phaeophyceae)

The seasonal variation in protein expression in the sporophyte of Saccharina japonica (Areschoug) Lane, Mays, Druehl and Saunders was investigated. High-quality proteins that are available for protein profiling were extracted by the ethanol/phenol extraction method, and 564 protein spots in total were detected. Proteins were identified through database search by combining Mascot and MS BLAST for 100 spots, and significant difference of expression level between the samples collected in winter and in summer was observed in the case of 95 spots. Within 67 spots upregulated in the samples collected in summer, vanadium-dependent bromoperoxidase (vBPO) were identified for 21spots. It is thought that the elevation of expression level of vBPO in summer depend on the activation of the functions: (1) elimination of active oxygen species and protection of the algal body from oxygen injury, (2) prevention of the growth inhibition due to the adherence of attached organisms, in the season.