Diagnostic PCR using DNA extracted during purification of the bacterial endosymbiont. A. When PCR was performed using a template prepared from the fat bodies, DNA fragments of B. cuenoti (b), mitochondria (m) and host Panesthia nuclei (h) were observed. B. Although the host DNA was disappeared after the Percoll centrifugation, only a trace of contamination of mitochondrial DNA was amplified. C. When the B. cuenoti DNA was digested with I-Ceu I separated using PFGE, no contaminations of mitochondrial and host's DNAs were detected. D. As PCR cycles were increased to be 35 cycles, no contaminations were detectable. M: 100-bp ladder.