Differential display of mRNAs related to amino acid metabolism in the endosymbiotic system of aphids.

Bacteriocytes harbouring Buchnera endosymbionts were isolated from young and old aphids, Acyrthosiphon pisum, and their mRNA populations were examined by the differential cDNA display and quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) technique. It was suggested that several gene products are produced when the symbiotic system is well organized in the young insect, whereas others are produced after the system becomes degenerate in old aphids. Among the gene products that were actively synthesized in the symbiotic system of the young host were putative aspartate aminotransferase, homoserine kinase and N-acetylglutamate synthase. These findings were consistent with the hypothesis that the symbiotic system utilizes glutamate to produce essential amino acids.