Protection of negative gravitaxis in Euglena gracilis Z against gamma-ray irradiation by Trolox C.

The protective effects of Trolox on the inhibition of negative gravitaxis in Euglena gracilis exposed to 200 Gy 60Co gamma-rays were examined using different concentrations (1, 10 and 100 microM). The orientation precision of the negative gravitaxis was quantified using the r-value. A significant decrease in the r-value was observed in gamma-irradiated samples (0.18+/-0.03) compared to those of non-irradiated samples (0.47+/-0.03). There were no significant changes in the r-value of cells exposed to 200 Gy gamma-rays by the addition of 1 or 10 microM of Trolox. A significant increase (0.19) in the r-value of cells exposed to 200 Gy with 100 microM Trolox was observed. The results indicates that Trolox at a concentration of 100 microM protects negative gravitaxis against 60Co gamma-ray irradiation at a dose of 200 Gy. It also suggests that the negative gravitaxis of Euglena gracilis is affected by free radicals.