Euglena gracilis is susceptible to cadmium (Cd) at high concentrations. The
re are no comparative data on cytotoxicity or abnormality of CdCl2 to E. gr
acilis Z and its achlorophyllous mutant SMZ. The present study examined the
cytotoxicity of CdCl2 under continual exposure at levels ranging from sub-
ppm to ppm, and assessed the effects of zinc (Zn) or cyanocobalamin (VB,,)
supplementation on the suppression of Cd-induced abnormal cell proliferatio
n and hypertrophy. With Zn levels restricted to I ppm [as Zn++], cell growt
h of both E. gracilis strains was reduced in proportion to Cd concentration
. More abnormal cells (hypertrophied, V-shape and starfish-shape) were obse
rved in both strains at sub-ppm levels of Cd. ZnSO4 supplementation from 2
to 63 ppm significantly suppressed the incidence of Cd-induced abnormality.
However, a significant increase in abnormal cells was observed following Z
n supplementation at levels of 125 and 250 ppm, which produced remarkable d
ifferences in cell morphology. The incidence of abnormal cells varied with
supplemented VB12 levels ranging from 4 to 250 ppb in both E. gracilis stra
ins. (C) 2001 Elsevier Science Inc. All rights reserved.