| Alcohol is a major component of the wine. In organisms ethanol molecules can get into blood circulation quickly after ingestion by oral, esophageal, stomach, intestine and other organs. And it can be transported to the tissues and organs for metabolism rapidly. The ethanol will enter into the liver after absorpted by stomach and intestine through the blood circulation, approximately95%will be metabolized in the liver. Studies have shown that ethanol reaching the liver are primary metabolized by alcohol dehydrogenase system. In this process, alcohol dehydrogenase is one of the important rate-limiting enzyme. Alcohol dehydrogenase is the NAD-dependent metalloenzyme, which widely expressed in different tissues of various biological, can reversibly catalyze the oxidation reaction of various alcohols and aldehydes. Reserches have demonstrated that the body’s metabolism of ethanol is closely related of alcohol dehydrogenase activity, and the blood’s alcohol concentration is closely related to ethanol metabolism pharmacokinetics. So we can come to understand the ethanol metabolism by assaying the activity of alcohol dehydrogenase and the blood’s ethanol concentration. At present, the researches about ethanol metabolism of mammalian are more clearly. There are also many reserches on ethanol metabolism of drosophila because of their special living environment. Silkworm as a mode of insects of the Lepidoptera, the study of ethanol metabolism has not been reported.This study focuses on the ethanol metabolism of silkworm. Bioinformatics analysis showed that there are7ADH coding genes in the silkworm genome. The expression profiles of BmADH genes in various tissues from Day-3,5th instar larvae indicated that BmADH1, BmADH6, BmADH7genes have high expression level in fatbody. In order to study the ethanol metabolism of silkworm, we treated the silkworm larvae by two methods, namely, injection and feeding ethanol to larvae. We then investigated the metabolism of ethanol in silkworm larvae using the gas chromatography and activity assay of ADH enzymes. In the present study, we found that the expression of BmADHl, BmADH6, BmADH7genes were up-regulated after being treated by injection of56%(v/v) ethanol. The results of enzyme assay revealed that the ADH enzyme activities were predominantly increased after1h treatment. The gas chromatography analysis showed that ethanol converted quickly into acetaldehyde in the larval hemolymph. Our study indicated that ethanol stimulation would induce the expression of the BmADH genes and increase the ADH enzyme activities, so ADH enzymes would participate the ethanol-metabolism quickly to protect the silkworm from the damage caused by high concentration of ethanol. |
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