A novel oxidant fumigation (NOF) is a commercial bleaching and disinfection agent. Recent study indicates its insecticidal activity. However, its exact mode of action to kill insects is not known. This study sets up a hypothesis that reactive oxygen species released from NOF is a main factor to kill insects. Plodia interpunctella is a lepidopteran insect pest infesting various stored grains. Both larvae and adults were susceptive to NOF. To test the hypothesis, we needed to identify antioxidant genes in P. interpunctella. Superoxide dismutase (SOD) and thioredoxin-peroxidase (Trx) were identified from P. interpunctella EST library using ortholog sequences of Bombyx mori. Both SOD and Trx were expressed in larvae of P. interpunctella expecially against oxidative stress induced by bacterial challenge. The bacterial challenge also induced some heat shock protein (HSP) genes. Similarly, different doses of NOF significantly induced both SOD and Trx genes. There results suggest that NOF at sublethal doses releases reactive oxygen species, which may be detoxified by the antioxidant activities of SOD and Trx of P. interpunctella.

Linuron is a pesticide with a weak anti-androgenic property, which impacts male reproductive organs. In this study, to clarify whether linuron affects the cellular antioxidant system of ventral prostate, gene expression patterns of the representative antioxidant enzymes such as glutathione peroxidase (GPx), selenoprotein P (SePP), and superoxide dismutase (SOD) were investigated in the rat ventral prostates exposed to linuron using real-time RT-PCR analyses. Sprague-Dawley rats castrated at 6 weeks old were treated with linuron (25, 50, or 100 mg/kg per oral) daily for 10 days after testosterone propionate administration (0.4 mg/kg) subcutaneously. As compared to normal control animals, mRNA levels of phospholipid hydroperoxide GPx (PHGPx), SePP, and Mn SOD significantly increased in the prostates exposed to linuron (25, 50, and 100 mg/kg). However, cytosolic GPx (100 mg/kg) and Cu/Zn SOD (25, 50, and 100 mg/kg) mRNA levels significantly decreased in the ventral prostates. These results indicate that linuron upregulates the expressions of PHGPx, SePP, and Mn SOD mRNAs, but down-regulates the expressions of cytosolic GPx and Cu/Zn SOD in rat prostates, suggesting that linuron may have dual effects in the cellular antioxidant system of prostate.

We isolated low temperature inducible genes using suppression subtractive hybridization (SSH) method and were able to obtain to cloneMLT107 gene encoding peroxiredoxin and aminotransferase. The full-length cDNA of MLT107 is 1,049 bp with an open reading frame (ORF) consisting of 261 amino acid (aa). Genomic southern blot confirmed that mungbean genome has two copies of MLT107 gene. Northern blot analysis was also carried out for the gene expression during ABA, NaCl, drought, wounding and H2O2 stresses. The expression of MLT107 gene significantly decreased by ABA, NaCl and drought stress, but wounding and H2O2 stress significantly induced MLT107 gene expression. Especially, H2O2 strongly induced the MLT107 gene expression. The expression of MLT107gene during low temperature stress started to increase in 3 h after treatment, and than slightly decreased and again increased at 24 h. Using GFP fusion vector, smGFP-MLT107 was targeted both to mitochondria and chloroplast. However, it was mostly targeted to mitochondria and partially targeted to chloroplast. For the functional analysis of MLT107, MLT107 recombinant protein was heterologously expressed in E.coli. The MLT107 recombinant cells showed enhanced antioxidant activity compared to that of vector control cells.