[DNA polymorphism analysis and some hints for oral presentation in English at the international meeting]

DNA workers are increasingly using short tandem repeat (STR) markers for parentage or identity testing because of the ease and rapidity of their typing and their high informativeness. We have been using simple, time-saving, cost-effective methods for STR polymorphism analysis. Using triplex-affinity-captured DNA from 5 microliters of whole blood for quintuplex PCR, we can type the FGA, D8S320, D11S554, TH01, and D16S537 loci simultaneously in 20 hours by Southern blotting with digoxigenin-labeled (AAAG)6. To further simplify allele detection, we produced a monoclonal anti-thymine-dimer antibody and successfully used it for detecting CTTT strands of STR amplicons that had been UV irradiated. DNA is readily available from buccal swabs. We were able to analyze STR polymorphisms in buccal cells that had been simply frozen and thawed. The procedure provides the best means of typing infants and bone-marrow-transplanted subjects. In addition, we were able to identify the human host of blood DNA extracted from a mosquito. We have demonstrated that STR analysis exhibits enormous power in solving deficiency cases of disputed parentage mostly because of the abundance of alleles and partly because of the existence of gender-specific markers. Revolutionizing molecular biology, the polymerase chain reaction (PCR) has enabled DNA workers to analyze STR loci. The Nobel-laureated Mullis hit on PCR in 1983 while driving his car along a moonlight mountain road, after he had had a fair amount of time available to think and putter as the result of the advent of automated oligonucleotide synthesis. This episode gives one an important lesson: maybe one should not be too busy with bench work to have time to putter around outside. Finally, some hints may be usefully added here for young forensic scientists who are anxious to improve their oral presentations in English at international medical conferences.