Role of stress in expression of eicosanoids in the red alga Murrayella periclados (C. Agardh) Schmitz (Rhodophyta, Rhodomelaceae)

Analyses of the concentration of the eicosanoid 12-hydroxyeicosatrienoic acid (12-HETE) and heat shock proteins in response to stress conditions were studied in the common Caribbean benthic marine alga Murrayella periclados (C. Agardh) Schmitz, after experimentally exposing the alga to different conditions of temperature and salinity. The eicosanoid concentration in lipid extracts and presence of stress proteins in protein extracts were evaluated in field-collected (wild) and cultured M. periclados. Cultured M. periclados was experimentally exposed to low and high temperature (15°C and 35°C) and low and high salinity (10 and 65 ppt) treatments. Control cultures were maintained at 25 °C and 35 ppt. Average values of eicosanoid concentration in field-collected M. periclados ranged from 575 to 750 ng/g, while under culture control conditions they ranged from 304.5 to 325.0 ng/g. Effect of treatments was evaluated immediately (time = 0) and at 10, 30 and 60 minutes after cessation of treatments. A significant increase in eicosanoid concentration was observed 10 minutes after cessation of high temperature and high salinity treatment periods, where average values of eicosanoid concentration ranged from 400 to 510 ng/g. The eicosanoid concentration in samples from low temperature and low salinity treatments was not different from control, and there was no evidence of stress protein expression in these samples. Stress protein 70 and stress protein 25 were the common stress proteins expressed in M. periclados following 30 and 60 minute exposures to high temperature and high salinity and analyzed immediately after treatment (time = 0). The observation of subsequent induction of heat shock proteins in treatments before the increase in 12-HETE concentration, provides an undefined role of this compound in stress response during treatment. However, the eventual increase in 12 HETE, 10 minutes after cessation of treatments, may be is related to the sustained presence of stress protein 25 after 30 and 60 minutes following high salinity and high temperature stress cessation. This study recognized, for the first time, the expression of stress protein 25 in a florideophycean algae.