Underground Radiobiology: A Perspective at Gran Sasso National Laboratory

Abstract

Scientific community and institutions (e. g., ICRP) consider that the Linear No-Threshold (LNT) model, which extrapolates stochastic risk at low dose/low dose rate from the risk at moderate/high doses, provides a prudent basis for practical purposes of radiological protection. However, biological low dose/dose rate responses that challenge the LNT model have been highlighted and important dowels came from radiobiology studies conducted in Deep Underground Laboratories (DULs). These extreme ultra-low radiation environments are ideal locations to conduct below-background radiobiology experiments, interesting from basic and applied science. The INFN Gran Sasso National Laboratory (LNGS) (Italy) is the site where most of the underground radiobiological data has been collected so far and where the first in vivo underground experiment was carried out using Drosophila melanogaster as model organism. Presently, many DULs around the world have implemented dedicated programs, meetings and proposals. The general message coming from studies conducted in DULs using protozoan, bacteria, mammalian cells and organisms (flies, worms, fishes) is that environmental radiation may trigger biological mechanisms that can increase the capability to cope against stress. However, several issues are still open, among them: the role of the quality of the radiation spectrum in modulating the biological response, the dependence on the biological endpoint and on the model system considered, the overall effect at organism level (detrimental or beneficial). At LNGS, we recently launched the RENOIR experiment aimed at improving knowledge on the environmental radiation spectrum and to investigate the specific role of the gamma component on the biological response of Drosophila melanogaster.

Editorial: The Genetic and Epigenetic Bases of Cellular Response to Ionizing Radiation

“…Many studies reported that people in high level background radiation area above 10 mSv/year showed no health risks for cancers or life-shortening, compared to the residents in other areas (Hendry et al, 2009). Furthermore, underground biology studies in Deep Underground Laboratories (DULs) characterized by substantial reduction of the exposure to environmental radiation background showed that background level of radiation could influence the sustaining the life of organisms, modulating the expression of several genes involved in protein metabolism and stress response (Esposito et al, 2020;Castillo et al).…”

Reduced Environmental Dose Rates Are Responsible for the Increased Susceptibility to Radiation-Induced DNA Damage in Larval Neuroblasts of Drosophila Grown inside the LNGS Underground Laboratory

“…The Gran Sasso National Laboratory (LNGS) at Assergi (L’Aquila, Italy) is one of the largest DULs in the world, hosting the largest number of biological experiments performed to date. Due to the 1400-m coverage of dolomitic rocks poor in uranium and thorium, at LNGS the flux of cosmic rays is considered negligible as it is reduced by approximately 6 orders of magnitude, while the neutron flux is 1000 times reduced with respect to the external environment [ 12 , 13 ]. The setting up of two dedicated facilities, namely, PULEX and COSMIC SILENCE for cell culture and animal housing, respectively, allowed researchers to gather several pieces of evidence on the influence of the deprivation of a natural level of environmental radiation in different model systems [ 12 , 14 ].…”

“…Due to the 1400-m coverage of dolomitic rocks poor in uranium and thorium, at LNGS the flux of cosmic rays is considered negligible as it is reduced by approximately 6 orders of magnitude, while the neutron flux is 1000 times reduced with respect to the external environment [ 12 , 13 ]. The setting up of two dedicated facilities, namely, PULEX and COSMIC SILENCE for cell culture and animal housing, respectively, allowed researchers to gather several pieces of evidence on the influence of the deprivation of a natural level of environmental radiation in different model systems [ 12 , 14 ]. In particular, a few years ago, we launched the FLYINGLOW project that aimed to determine whether the LNGS’s underground environment could affect the growth and development of the well-established model organism, Drosophila melanogaster .…”

“…The characterization of the radiation field remains a crucial point for the interpretation of the biological effects, and dosimetric measurements should be constantly carried out not only underground but also in the reference laboratory. Furthermore, the modulation of the radiation field inside the DULs through the implementation of devices that could modulate some of these components could provide insights into the mechanisms underpinning the observed biological effects [ 12 , 18 ].…”

First transcriptome profiling of D. melanogaster after development in a deep underground low radiation background laboratory

“…Growth rate inhibition, increased sensitivity to radiation, delayed recovery after return to natural background conditions, alteration in expression of several genes concerned with ribosomal proteins, membrane transport, respiration, reparation and antioxidant regulation for increased ROS removal were observed in experiments on mammalian cell cultures (TK6, V79, M10, L5178Y, FD-LSC-1) and unicellular organisms ( Paramecium tetraurelia , Synechococcus lividus , Shewanella oneidensis , Deinococcus radiodiodurans , Saccharomyces cerevisiae ) [ 11 , 12 , 14 , 17 , 18 , 24 , 25 ]. The first multicellular organism used for determination of the effects of low-radiation background was the fruit fly in projects FLYINGLOW and RENOIR [ 20 , 26 ]. These experiments established that D .…”