Masumi Watanabe

Oxidative stress-induced cellular damage caused by UV and methyl viologen in Euglena gracilis and its suppression with rutin.

The effects of ultraviolet radiation (UV-A: 320-400 nm and UV-B: 280-320 nm) and methyl viologen (MV) single or combined exposure, on the cell growth, viability and morphology of two strains of the unicellular flagellate Euglena gracilis, using the Z strain as a plant model and the achlorophyllous mutant SMZ strain as an animal model were investigated. Cell growth was not affected by MV only, whereas UV-A or UV-B single and combined exposure with MV inhibited the cell growth or decreased the viability. The SMZ strain had a higher number of abnormal cells than the Z strain after the third dose of UV-B was delivered simultaneously with MV. The abnormal cell number decreased when E. gracilis SMZ cells were preincubated with 100 microM rutin prior to the UV-B and MV exposure. There were higher abnormal cell numbers with groups exposed to UV rather than MV single exposure. Combined exposure to UV-B and 200 microM MV induced the highest levels of TBARS in both strains, and with the supplementation of rutin these high levels were suppressed. These results suggest that UV-A or UV-B irradiation alone or combined with MV cause considerable oxidative damage in E. gracilis cells, and rutin supplementation may suppress their adverse effects.

Cadmium-induced abnormality in strains of Euglena gracilis: morphological alteration and its prevention by zinc and cyanocobalamin.

Euglena gracilis is susceptible to cadmium (Cd) at high concentrations. There are no comparative data on cytotoxicity or abnormality of CdCl2 to E. gracilis 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 (VB12) supplementation on the suppression of Cd-induced abnormal cell proliferation and hypertrophy. With Zn levels restricted to 1 ppm [as Zn++], cell growth of both E. gracilis strains was reduced in proportion to Cd concentration. More abnormal cells (hypertrophied, V-shape and starfish-shape) were observed 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 Zn supplementation at levels of 125 and 250 ppm, which produced remarkable differences in cell morphology. The incidence of abnormal cells varied with supplemented VB12 levels ranging from 4 to 250 ppb in both E. gracilis strains.

Cadmium-induced synthesis of HSP70 and a role of glutathione in Euglena gracilis

Abstract The effect of cadmium-induced oxidative stress, with or without glutathione supplementation, was investigated in the single cell eukaryotic phytoflagellate, Euglena gracilis strains Z and its achlorophyllous mutant SMZ as experimental models. Both these strains actively synthesize thiols to prevent or resist cadmium toxicity. The content of glutathione, as a representative antioxidant, was also examined in both strains. Exposure to cadmium induced heat-shock protein 70 (HSP70) synthesis in both strains of E. gracilis. Glutathione supplementation also induced HSP70. Overall, these results indicate that glutathione was closely linked to the induction of stress-related proteins. The sensitivity to cadmium-stress was higher in strain Z than SMZ. The results suggest that chloroplasts may have a role in the regulation of HSP70 expression. The relationship between HSP70 and GSH levels is still far from understood, and further research may shed light upon their up-regulation in the presence of Cd.

Robust speech recognition for similar pronunciation phrases using MMSE under noise environments

In this paper, we propose a robust speech recognition method for similar pronunciation phrases. Along with the popularization of information devices such as personal computers and smart-phones, many applications controlled by voice have spread in the society. In order to increase the speech accuracy under a real environment, it is extremely important to discriminate similar pronunciation phrases. In the proposed method, linear prediction theory (LPC) is used for spectral analysis while cepstrum mean subtraction (CMS) and dynamic range adjustment (DRA) is used for a noise reduction method. The speech accuracy was recorded 68.7 % in SNR 10 dB by using the proposed methods. In conclusion, LPC+CMS/DRA is the most effective method to discriminate similar pronunciation phrases.