Polyamine composition and expression of genes related to polyamine biosynthesis in an aphid endosymbiont, Buchnera

Polyamine composition in an aphid endosymbiotic bacterium, Buchnera sp., was determined by high-performance liquid chromatographic analysis. We found that Buchnera contained virtually only a single polyamine, spermidine. The spermidine content of Buchnera was considerably higher in young aphids and tended to decrease with the age of the host. Expression of speD and speE, whose gene products are key enzymes in the synthesis of spermidine, was analyzed by real-time quantitative reverse transcription-PCR. It was shown that the levels of their mRNAs fluctuated in line with the spermidine content.