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The recent technology of amplification of DNA sequences by the polymerase chain reaction (PCR) has already proved to be a very useful tool for the analysis of variable number of tandem repeat (VNTR) loci. Short tandem repeat (STR) loci appear as other promising PCR-based identification systems. In fact, DNA typing based on PCR amplification of STRs is very sensitive and allows to overcome major problems encountered when using the RFLP method, such as typing of very small amounts of DNA, highly degraded DNA or mixtures of DNA from more than one individual.Two STR systems, HUMTH01 (a tetranucleotide repeat (AATG) sequence located on chromosome 11) and HUMFES/FPS (a tetranucleotide repeat (ATTT) sequence located on chromosome 15) were investigated in order to determine allele and genotype frequencies for a French caucasian population sample.HUMTH01 and HUMFES/FPS alleles were amplified by the use of PCR and amplified STR sequences were analyzed on 6% Hydrolink Long Ranger gels and visualized by silver staining.The study was conducted on a sample of unrelated individuals (N ≈ 190) randomly selected from the French caucasian population. The genotype distributions met Hardy-Weinberg expectations for both HUMTH01 and HUMFES/FPS STR systems. Furthermore, an additional allele, never reported before was observed at the HUMFES/FPS locus: it migrates as an allele containing 7 repeat units and corresponds to the smallest allele identified for this locus.

The polymerase chain reaction (PCR) amplification of short tandem repeat (STR) loci has already proven to be a method of choice for large scale typing of DNA samples in which the conventional restriction fragment length polymorphism (RFLP) technique is ineffective.A quadruplex PCR including HUMvWFA31A, HUMF13A01, HUMTH01, and HUMFESPFS STR loci is used successfully for routine forensic applications in our laboratory. However, the need to increase the discrimination power of the PCR systems used prompted us to develop a second system of a pentaplex PCR for the analysis of 4 additional STR loci (HUMD8S1179, HUMD18S51, HUMD21S11, and HUMFIBRA) and the sex determination by amplification of a segment of the X-Y homologous Amelogenin gene. Allele and phenotype frequencies for these 4 STR systems were obtained by multiplex amplification, from approximately 200 randomly selected and unrelated French Caucasian individuals. Statistical calculations for these phenotype distributions met expectations for Hardy-Weinberg equilibrium. Furthermore, the French allelic frequencies of D18S51, D21S11, and HUMFIBRA loci were compared with the data obtained by the Forensic Science Service (UK) for the British Caucasian population and proved to be similar.

Bean (Phaseolus vulgaris cv. Saxa) chloroplasts contain two tRNAPhe species, namely tRNAPhe1 and tRNAPhe2. By sequence determination, we show that tRNAPhe2 is identical to the previously sequenced tRNAPhe1 except for two undermodified nucleotides. By reversed-phase chromatography analyses, we demonstrate that the relative amounts of these two chloroplast tRNAsPhe vary during leaf development: in etiolated leaves the undermodified tRNAPhe2 only represents 15% of total chloroplast tRNAPhe, during development and greening it increases to reach 60% in 8-day-old leaves, and it then decreases to 9% in senescing leaves.

DNA typing is a useful tool in forensic cases for determining the identity of remains of humans who have been dead for various periods of time. DNA fingerprinting can be achieved only if high molecular weight DNA (HMWDNA) is extracted from the tissue samples of the bodies even after a long postmortem delay. Analyses were performed on various tissues collected during forensic autopsies of 24 bodies known postmortem ages. Tissues such as blood and kidney were found to be unsuitable for DNA fingerprinting because of a rapid degradation of the DNA after a period of one week. HMWDNA could be successfully extracted from brain cortex regardless of postmortem age.