Iron-dependent oxidative stress in Chlorella

ESTEVEZ MS; MALANGA G; PUNTARULO S

PLANT SCIENCE

ELSEVIER IRELAND LTD

Lugar: Amsterdam; Año: 2001 vol. 161 p. 9 - 17

0168-9452

The role of iron as catalyst for oxidative stress was studied during the development of Chlorella ulgaris cells. Increases on iron availability beyond 200 M led to a decrease in the growth rate of the cultures of C. ulgaris. Quantification of the EPR signals of POBN/lipid radicals adducts indicated that iron addition increased lipid radical content in the membranes (more than three-fold at 500 M Fe). The ratio of ascorbyl radical content/ascorbate content was increased in cells exposed to 500 M iron as compared to standard conditions (90 M Fe). -Carotene content was not affected by iron addition, however, -tocopherol, ascorbate and total thiol content in C. ulgaris cells was increased when iron supply was higher than 90 M. The morphology of the cells developed under 500 M iron showed a decreased number of ribosomes and alterations in the cellular starch deposits as compared to the cells grown at 90 M iron. Exposure to UV-B increased the content of lipid radicals and affected cellular internal structure as compared to non-irradiated cells developed at 500 M iron. Even though results from model systems cannot be directly used to predict ecological effects, these data suggest that oxidative stress triggered by an excess of iron could affect cellular growth and have a negative impact to phytoplankton.