Enhancement of the attractiveness of mice as mosquito bait by injection of methionine and its metabolites

Abstract

In the preceding experiments, methionine was found to enhance the attractiveness of mice for mosquito biting when an aqueous solution was inpregnated on the body surface. Further experimentation on this was conducted by injection of 0.1ml. of 0.5% methionine into a mouse intraperitoneally. Since there was no significant increase of methionine in the blood serum of the treated mice, and since blocking the metabolic pathways of methionine by addition of ethionine cancelled the enhanced attractiveness, some metabolites rather than the intact methionine were suspected to be responsible for this effect. Following the metabolic pathways of methionine in vivo, various probable metabolites were tested, and glycine was found to enhance attractiveness significantly, and cysteine and pyruvic acid somewhat less. Other probable metabolic compounds, creatine, choline and cystine, and taurine and urea actually detected by chromatographic analysis of the blood serum did not contribute to increased attractiveness. Since the contents of glycine and cysteine did not increase significantly in the blood serum when treated mice exhibited the enhanced effect, further metabolic compounds of these are suspected to be responsible for this. The desulfulization process of cysteine to pyruvic acid could not be related to this effect.