Résumé
The aim of the study was to examine the liver tissue damage induced by nanosized-TiO2 in mouse. The biochemical parameters of liver, namely glutamic-oxaloacetic transaminase, glutamic-pyruvic transaminase and alkaline phosphatase were enhanced approximately 18%, 35% and 69% by exposure to nanosized-TiO2, respectively. The nanosized-TiO2 accumulated in the periphery of sinusoid in liver when the ultrastructure was examined through transmission electron microscopy. Enzymes, such as superoxide dismutase, catalase and aldehyde dehydrogenase were significantly inhibited by 22%, 38% and 15%, respectively, whereas glutathione peroxidase was constant following exposure to nanosized-TiO2.
Résumé
Benz[a]anthracene is a ubiquitous environmental contaminant formed during the incomplete combustion of organic material. Some of the metabolites of benz[a]anthracene are known to be toxic and carcinogenic. In this investigation, benz[a]anthracene-induced oxidative damage to lymphocyte DNA was evaluated with the Comet assay (single cell gel electrophoresis). The level of oxidative DNA damage caused by benz[a]anthracene increased in a dose-dependent manner (24, 49) and oxidative DNA damage was significantly inhibited by 5 and 10 μg ml-1 ascorbate, 5 μg ml-1 polyphenols, as well as 5 and 10 μg ml-1 curcumin. Moreover, traditional Korean medicinal herbs such as Acanthopanax and ginseng significantly reduced DNA damage. The results demonstrate that antioxidant supplementation to lymphocytes inhibits oxidative DNA damage in vitro, supporting an inhibitory effect against oxidative DNA damage, probably due to reduction of reactive oxygen species production induced by benz[a]anthracene.
Résumé
The effects of gibberellin (GA) on the expression of GA-20 oxidase gene homolog were examined in light-grown seedlings and dark-grown seedlings of DongJinByeo. The growth rates of the stems of etiolated seedlings were faster than those of green seedlings. However, upon addition of GA to these seedlings, the stem growth rates of green seedlings were faster than those of etiolated seedlings. To understand the molecular mechanism of GA gene regulation in DongJinByeo, total RNA from DongJinByeo was hybridized with cDNA of GA-20 oxidase gene homolog. Greater accumulation of transcript of GA-20 oxidase gene homolog was observed in green seedlings than in etiolated seedlings. However, upon addition of GA, higher accumulation of the gene transcript was found in etiolated seedlings than in green seedlings, indicating that expression of the transcript of GA-20 oxidase gene homolog might be inhibited by light. These results suggest that light might regulate feedback control of the transcript of GA-20 oxidase gene homolog in DongJinByeo.
Sujets)
Séquence nucléotidique , Amorces ADN , Rétroaction/effets des radiations , Lumière , Mixed function oxygenases/génétique , Oryza/enzymologie , Réaction de polymérisation en chaîneRésumé
The effects of salicylic acid (SA) on the activity of total peroxidase and the patterns of isoperoxidases of cultured tobacco cells were investigated. The total peroxidase activity of tobacco cells was inhibited by 70% when the cells were treated with 5 mM SA for one week. The peroxidase activity of tobacco cells is declined by 90% in the presence of 30 mM SA. Moreover, the activity of isoperoxidases C3, A1, and A3 decreased dramatically with increasing SA concentration, while, one of the anodic isoperoxidases, A2, was somewhat resistant to SA treatment. When isoperoxidase C3 was isolated, SA inhibited the activity of purified C3 in a concentration-dependent manner. The IC50 of isoperoxidase C3 was approximately 0.45 mM. However, the inhibition of isoperoxidase C3 activity was removed by the addition of Fe2+ ion. The possible mechanism of inhibition of peroxidase by SA is discussed.