Are the DMs the result of gene amplification of the telomerase components after irradiation?

Full text: The main objective is to test the hypothesis that considers the DM (double minutes) as the cytological sign of telomerase gene amplification after irradiation, on human, in vivo and in vitro. Irradiations were performed at Electron Accelerators Laboratory, National Institute for Laser, Plasma and Radiation Physics, Magurele-Bucharest, Romania. The samples were irradiated using an ALIN 10 linear electron accelerator. The peripheral blood for in vitro studies was collected from an aged 25, healthy, non-smoker donor and for in vivo studies from five subjects who are working in a potentially mutagenic environment. The doses used to irradiate in vitro human blood were: 4, 6, 8, 10 Gy. For FISH the probes were: one probe for revealing the telomeres and the second one for the RNA telomerase compound. For the molecular analyses, we used the TRAPeze Telomerase detection kit. The most informative dose for the appearance of DM (frequency 26%) was at 8 Gy, so we have chosen this dose in order to perform further experiments. In vivo tests did not revealed any DMs. Because of that, in our further studies, no more experimental work was done on this samples. After the in vitro irradiation, in cases of chromosomal interchanges or translocations, we did not identify the telomeric fluorescent signal at the chromosomal ends. This observation and the fact that we found the signal on different acentric fragments revealed that the radiation generates important destruction at the level of chromosomal ends. From the FISH analysis, we detect the RNA telomerase component on chromosome 3 q, at the two homologous chromosomes in normal probes and also in irradiated one. The fact that we did not found additional signals after irradiation revealed that the telomerase is not amplified in order to repair the broken telomeres. We have tried to detect changes in expression of the telomerase enzyme normal/irradiated sample by the TRAPeze detection kit, all the samples analyzed revealing the same reaction - no amplified activity of the telomerase enzyme in normal/irradiated samples was detected. We can conclude that, in spite of the DM appearance, the telomerase enzyme seems to be not over expressed or reactivated in any of the irradiated samples, so the initial theory might be questioned