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The detection of restriction fragment length polymorphisms (RFLP) (1) in DNA extracted from forensic samples remains impossible in a significant number of cases due to deterioration and contamination of the biological material and the extremely low quantities of DNA isolated. The polymerase chain reaction (PCR) is a recent and particularly convenient method for analysing and typing very small amounts (10-20 ng) of degraded human DNA. DNA analysis at the level of a few cells present in forensic samples such as bloodstains, semen stains, vaginal swabs and head hair bulbs now appears possible using DNA amplification. A PCR protocol was adapted to simultaneously amplify a Y-specific DNA repeat sequence from the DYZ1 locus and an X-specific DNA repeat sequence from the DXS424 locus. The co-amplified Y-specific DNA fragment (102 bp) and X-specific DNA fragments (181-199 bp) were visualized on an ethidium bromide-stained 4% agarose gel. The male or female type of the amplified DNA extracted from blood samples, bloodstains, semen stains, vaginal swabs, brain tissue and 1, 2, 5, or 10 head hair bulbs was determined.

DNA fingerprinting analysis was used to investigate genetic variability within and between three wild populations of Eulemur macaco living on two islands and on the mainland. The analyses revealed that the genetic variability of the population from the smaller island was, as expected, lower than that from the larger island. Surprisingly, on the larger island the genetic variability was greater than on the mainland. These results, in agreement with those previously obtained from blood markers, are discussed in relation to the history of these populations. In addition, the study suggests that settlement of the smallest island was not only by animals originating from the mainland, as previously proposed on the basis of blood marker data, but also by lemurs from the nearby, larger, island. Evidence is presented that reliable information about population structure can be derived only from studies using different genetic markers. This information is important to enable appropriate conservation programmes to be designed.

After a rape, women who are pregnant often elect to abort the fetus. The authors describe ten cases in which deoxyribonucleic acid (DNA) typing was performed on the aborted fetal material to provide evidence of the genetic constitution of the suspect. The problems encountered with this new technique are discussed.

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