The Cosmic Silence Experiment Rome, November 26 th 2007Massimo Pinto Junior Grants F. Antonelli, C. Carbone, M. Pinto

What is it? A unique experiment on the biological effects of background environmental radiation on living human cells

Presentation Sequence Rationale Before Cosmic Silence Cosmic Silence experimental model Results Developments

Biological responses to low doses of ionizing radiation look more complex than originally thought. Once DNA damage-centred... Rationale Now broadened to include non (DNA)-targeted effects: Bystander effects Genomic Instability Adaptive Responses Ionising radiation

Adaptive Responses conditioning dosechallenge dose Effect +

Adaptive Responses - II Cronic conditioning with 3 H β-particles challenge dose Olivieri, Bodycote and Wolff Science, 1984 Effect +

Radiation is everywhere Cosmic Inhaled Radon Rocks Radioactive Elements Plants Bodies Adapted from:

Most background radiation is natural. It has always been here. People have always lived with it. In fact, the body has developed repair mechanisms to deal with negative effects of background radiation Background Radiation Adapted from:

Rationale What if background radiation was significantly reduced? Would living organisms lose their adaptation? Would we be less prepared to an insult of ionizing radiation?

Two laboratories for two different background radiation levels ISS Rome Roma Gran Sasso d’Italia Teramo INFN Lab km 1400 m INFN-LNGS Is background radiation a conditioning agent?

240 µGy/month 222 Rn  (Earth and cosmic) Cosmic n, p 222 Rn  (Earth) 3 µGy/month 1 Gy = 1 Joule / kg In vitro dosimetry

Our past results Yeast (S. Cerevisiae), 1995 Chinese Hamster cells, 2002

3 months Chinese hamster cells 9 months Low background Rome t0

So, good news for all Yeast cells and Chinese Hamsters in the audience. But please, don’t go live inside any mountain.

Working hypothesis Natural background environmental radiation can adapt human cells in vitro to acute doses of ionizing radiation

The Human lymphoblastoid line TK6 Cosmic Silence Experiment Immortalised - goes on for long times 2 independent genetic loci for mutation experiments for two functionally distinct DNA repair mechanisms Frequent criopreservations in LN 2 Everything rigorously identical

Culture Monitoring

Measurements – Year 1 DNA damage –Micronuclei induction Parallel gene expression analysis Apoptosis “Reactive Oxygen Species” (ROS)

DNA damage, 6 th month conditioning + + = 2.0 Gy Micronuclei induction (%)

DNA damage, 6 mo. + + = 2 Gy

Cancer Risk A-Bomb survivors and nuclear industry workers, epidemiological data Radiation Dose (Gy) or dose rate Excess cancer risk from radiatoin LNT model extrapolation to low doses Cosmic silence experiment

Coming up next Human cells – LNGS cells back to Rome after 12 months. Searching for re- adaptation in vivo systems such as C. Elegans are being considered

Massimo P. Francesca A. Cristina C.