[Quantification of human DNA from forensic samples via real time PCR by the help of a telomerase assay]. / Quantifizierung humaner DNA aus forensischen Proben mittels Real-time PCR unter Verwendung eines Telomerase-Assays.

Quantitative data concerning the content of human DNA and the effect of PCR inhibitors in a sample would provide very important information within a forensic DNA analysis. With the help of real-time PCR it is possible to test DNA samples for these influencing factors. However, the amplified DNA segments detected by means of usual TaqMan DNA probes are longer than most of the short tandem repeats to be investigated. Because of possible DNA degradation, a DNA probe located in the human telomerase transcriptase gene was successfully tested on forensic samples in the present study. Its amplified DNA segment is only 94 bases in length and, thus, shorter than the short tandem repeats. Therefore, it seems perfectly suited for the examination of degraded DNA. With the telomerase probe it was possible to obtain accurate results of the influence factors mentioned above. Based on the findings of this examination and on a case example, in which the poorly preserved remains of a baby were subjected to paternity testing, the possible uses of the telomerase assay are discussed.

Saccharomyces cerevisiae translational activator Cbs1p is associated with translationally active mitochondrial ribosomes.

In the yeast Saccharomyces cerevisiae, mitochondrial translation of most, if not all, mitochondrially encoded genes is regulated by an individual set of gene-specific activators. Translation of the COB mRNA encoding cytochrome b requires the function of two nuclearly encoded proteins, Cbs1p and Cbs2p. Genetic data revealed that the 5'-untranslated region of COB mRNA is the target of both proteins. Recently, we provided evidence for an interaction of Cbs2p with mitochondrial ribosomes. We demonstrate here by means of blue native gel electrophoresis, density gradient centrifugation and tandem affinity purification that a portion of Cbs1p is also associated with mitochondrial ribosomes. In addition, we demonstrate that the amount of ribosome-associated Cbs1p is elevated in the presence of chloramphenicol, which is known to stall ribosomes on mRNAs. In the presence of puromycin, which strips off the mRNA and nascent protein chains from ribosomes, Cbs1p is no longer associated with ribosomes. Our data indicate that the observed interaction is mediated by ribosome-bound mRNA, thus restricting the association to ribosomes actively translating cytochrome b.