The Cosmic Silence experiment: on the putative adaptive role of environmental ionizing radiation.
Previously we reported that yeast and Chinese hamster V79 cells cultured under reduced levels of background environmental ionizing radiation show enhanced susceptibility to damage caused by acute doses of genotoxic agents. Reduction of environmental radiation dose rate was achieved by setting up an underground laboratory at Laboratori Nazionali del Gran Sasso, central Italy. We now report on the extension of our studies to a human cell line. Human lymphoblastoid TK6 cells were maintained under identical in vitro culture conditions for six continuous months, at different environmental ionizing radiation levels. Compared to "reference" environmental radiation conditions, we found that cells cultured in the underground laboratories were more sensitive to acute exposures to radiation, as measured both at the level of DNA damage and oxidative metabolism. Our results are compatible with the hypothesis that ultra-low dose rate ionizing radiation, i.e. environmental radiation, may act as a conditioning agent in the radiation-induced adaptive response.
Carbone
M C
MC
Museo Storico della Fisica e Centro Studi e Ricerche "Enrico Fermi", Rome, Italy.
Pinto
M
M
Antonelli
F
F
Amicarelli
F
F
Balata
M
M
Belli
M
M
Conti Devirgiliis
L
L
Ioannucci
L
L
Nisi
S
S
Sapora
O
O
Satta
L
L
Simone
Giustina
G
Sorrentino
E
E
Tabocchini
M A
MA
D000975:Antioxidants / Q000378:metabolism; D001417:Background Radiation; D002374:Catalase / Q000378:metabolism; D002460:Cell Line; D049109:Cell Proliferation / Q000528:radiation effects; D004249:DNA Damage; D004307:Dose-Response Relationship, Radiation; D004781:Environmental Exposure; D006801:Humans; D008214:Lymphocytes / Q000528:radiation effects*; D015162:Micronucleus Tests; D011839:Radiation, Ionizing; D011874:Radiometry; D014965:X-Rays
D000975:Antioxidants; D002374:Catalase