Effects of gamma-ray and high energy carbon ion irradiation on swimming velocity of Euglena gracilis.
The effects of gamma-ray and high energy carbon ion irradiation on the swimming velocity of the photosynthetic flagellate Euglena gracilis strain Z were studied, focusing on a dose-effect relationship. Cells were exposed to 60Co gamma-rays at 6 doses of 10, 15, 20, 40, 100 and 200 Gy for water, and also to 290 MeV/amu carbon ions from the Heavy Ion Medical Accelerator in Chiba at 7 doses (5, 10, 15, 20, 50, 100 and 200 Gy for water). The swimming velocity was measured by a biomonitoring system, called ECOTOX. The swimming velocities of Euglena gracilis cells were significantly decreased by >40 Gy gamma-rays and >5 Gy carbon ions, respectively. The 50% effective doses for inhibition, 34 +/- 4 Gy (gamma-rays) and 13 +/- 1 Gy (290 MeV/amu carbon ions), were estimated from the best fit to data of the logistic model. The relative biological effectiveness (2.6 +/- 0.4) was calculated by the ratio of 50% effective doses. The inhibition of the swimming velocity of the cells irradiated with gamma-rays was still present after 3 days, while recovery of the swimming velocity was shown in the cells exposed to 290 MeV/amu carbon ions. It is suggested that ionizing radiation inhibits ATP production and/or increases frictional drag on beating of the flagellum, thus decreasing swimming velocity.
Sakashita
T
T
National Institute of Radiological Sciences, Inage, Chiba, Japan. tetsuya@nirs.go.jp
Doi
M
M
Yasuda
H
H
Fuma
S
S
Hader
D-P
DP
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002244:Carbon; D004307:Dose-Response Relationship, Radiation; D005056:Euglena gracilis / Q000378:metabolism / Q000528:radiation effects*; D005720:Gamma Rays; D020450:Heavy Ions; D016015:Logistic Models; D009043:Motor Activity / Q000528:radiation effects; D012062:Relative Biological Effectiveness; D013550:Swimming
D002244:Carbon; D000255:Adenosine Triphosphate