Possible physiological mechanisms for production of hydrogen peroxide by the ichthyotoxic flagellate Heterosigma akashiwo |
| |
Authors: | Twiner Michael J; Trick Charles G |
| |
Institution: | Department of Plant Sciences, University of Western Ontario, London, Ontario, Canada N6A 5B7 |
| |
Abstract: | Blooms of the toxic red tide phytoplankton Heterosigma akashiwo(Raphidophyceae) are responsible for substantial losses withinthe aquaculture industry. The toxicological mechanisms of H.akashiwoblooms are complex and to date, heavily debated. One putativetype of ichthyotoxin includes the production of reactive oxygenspecies (ROS) that could alter gill structure and function,resulting in asphyxiation. In this study, we investigated thepotential of H.akashiwo to produce extracellular hydrogen peroxide,and have investigated which cellular processes are responsiblefor this production. Within all experiments, H.akashiwo producedsubstantial amounts of hydrogen peroxide (up to 7.6 pmol min1104 cells1), resulting in extracellular concentrationsof ~0.5 µmol l1 H2O2. Measured rates of hydrogenperoxide production were directly proportional to cell density,but at higher cell densities, accuracy of H2O2 detection wasreduced. Whereas light intensity did not alter H2O2 production,rates of production were stimulated when temperature was elevated.Hydrogen peroxide production was not only dependent on growthphase, but also was regulated by the availability of iron inthe medium. Reduction of total iron to 1 nmol l1 enhancedthe production of H2O2 relative to iron replete conditions (10µmol l1 iron). From this, we collectively concludethat production of extracellular H2O2 by H.akashiwo occurs througha metabolic pathway that is not directly linked to photosynthesis. |
| |
Keywords: | |
本文献已被 Oxford 等数据库收录! |
|