Genomic stability following exposure of human lymphocytes to THz radiation and Rafi Korenstein1 ,Avi Gover2 Avital Korenstein-Ilan1 This paper has been carried out with financial support from the Commission of the European Communities, specific RTD programme "Quality of Life and Management of Living Resources", QLK4-2000-00129  "Tera-Hertz Radiation In Biological Research, Investigation on Diagnostics and study on potential Genotoxic Effects". It does not necessarily reflects its view and in no way anticipates the Commission's future policy in this area

Genomic instability is characterized by: Aneuploidy - Loss or gain of genetic material - chromosomes (numerical aberrations) Asynchronous replication – loss of the temporal order of coordinated replication, indicative of changes in gene expression Replication timing – changes in the time during s-phase that the sequence is replicated

Interphase FISH analysis for aneuploidy

Genomic instability is characterized by: Aneuploidy - Loss or gain of genetic material - chromosomes (numerical aberrations) Asynchronous replication – loss of the temporal order of coordinated replication, indicative of changes in gene expression Replication timing – changes in the time during s-phase that the sequence is replicated

 

FISH analysis of replication timing and coordination

Experimental System Cellular model system - Human peripheral blood cells (T-lymphocytes). 1.5 ml of PB were placed into each of 5 small culture flasks to give a 1.6mm layer. Exposure system – a home-made incubator adapted for THz radiation Exposure parameters – Exposure to CW 100MHz source at a power density of 0.06mW/cm2 for 20, 40 and 60 min.

I = I0e-αx SAR(x=0) = -α (dI/dx).(1/ρ) = I0/(1/α).(1/ρ) I0 = 0.06 mW/cm², 1/α = 0.013 cm , ρ = 1 SAR (x=0) = 4.6 mW/gr SAR Power Density 4.6 mW/gr 0.06 mW/cm² Experiment (100MHz) 4.0 mW/gr (0.01-10 GHz) 1.0 mW/cm² (2-300 GHz) IRPA based general public exposure limit

exposure set-up

Human cell cultures After the relevant exposure, 15ml of medium were added to each flask and the contents divided between three flasks. Cells were harvested following 72 hours in culture using a standard cytogenetic protocol.

Chromosomal Aneuploidy

Asynchronous replication ** * * p<0.002; ** p<0.0003

Early replication * * p<0.002

Late replication * * p<0.03

Results: There were no changes in chromosome 11 in any of the assays applied. While there was no numerical changes to chromosome 17, functionally related aberrations were observed (replication timing and coordination) when the exposure system was on for the longest time tested.

conclusions: There seem to be some epigenetic effects of the THZ radiation, at the parameters studied, on chromosome 17. the observed effects seem to have a dose effect. Further studies are needed to validate our preliminary results.

Relevance to cancer ** * * * * p<10-4 ; ** p<10-3

metaphase index

replication timing * * p<0.007