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

Mikhail Zarubin,Yuri Gavriljuk,Elena Kravchenko,Vladimir Kazalov,Albert Gangapshev,Gayle E Woloschak

doi:10.1371/journal.pone.0255066

Mikhail Zarubin, Yuri Gavriljuk + Show 4 more

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https://doi.org/10.1371/journal.pone.0255066

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Abstract

Natural background radiation is a permanent multicomponent factor. It has an influence on biological organisms, but effects of its deprivation still remain unclear. The aim of our work was to study for the first time responses of D. melanogaster to conditions of the Deep Underground Low-Background Laboratory DULB-4900 (BNO, INR, RAS, Russia) at the transcriptome level by RNA-seq profiling. Overall 77 transcripts demonstrated differential abundance between flies exposed to low and natural background radiation. Enriched biological process functional categories were established for all genes with differential expression. The results showed down-regulation of primary metabolic processes and up-regulation of both the immune system process and the response to stimuli. The comparative analysis of our data and publicly available transcriptome data on D. melanogaster exposed to low and high doses of ionizing radiation did not reveal common DEGs in them. We hypothesize that the observed changes in gene expression can be explained by the influence of the underground conditions in DULB-4900, in particular, by the lack of stimuli. Thus, our study challenges the validity of the LNT model for the region of background radiation doses below a certain level (~16.4 nGy h-1) and the presence of a dose threshold for D. melanogaster.

Highlights

All living organisms have been affected by natural background radiation since the time when life on the Earth began
Estimation of the total background radiation in DULB-4900 and in the laboratory of the ground institute building of Baksan Neutrino Observatory (BNO) (INR, RAS). As it has been already demonstrated for biological experiments in deep underground lowbackground laboratories [11, 21, 23] exceptional shielding of such laboratories reduce the muon, neutron and gamma fluxes by ~103 times (Table 1) and some components may be assumed to be negligible in our calculations of total background radiation
D. melanogaster had been already efficiently used for biological studies as an animal model for non-human natural background dosimetry [20, 51]

Summary

Introduction

All living organisms have been affected by natural background radiation since the time when life on the Earth began. The background radiation on the surface of the Earth consists of γrays, α- and β-particles, neutrons, radon, cosmic particles etc. The dose rate of this background radiation varies in the range of 10−7–10−5 Gy h-1. Throughout life, all living organisms are constantly exposed to low doses of natural background radiation which induces generation of reactive oxygen species (ROS) and radicals in biological matter as well as destruction of biomolecules and cell structures. NGy h-1 Neutrons, nGy h-1 (cm-2s-1) Muons and cosmic rays, nGy h-1 (cm-2s-1) Radon, nGy h-1 (Bq m-3). Ground laboratory in the institute building, BNO (INR, RAS). Chamber of DULB-4900, BNO (INR, RAS) 1.19 (35) NaI(Tl) crystal scintillation detector [32] Helium proportional counter [32, 33]

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