Gamma radiation induces dose-dependent oxidative stress and transcriptional alterations in the freshwater crustacean Daphnia magna

Abstract

Among aquatic organisms, invertebrate species such as the freshwater crustacean Daphnia magna are believed to be sensitive to gamma radiation, although information on responses at the individual, biochemical and molecular level is scarce. Following gamma radiation exposure, biological effects are attributed to the formation of free radicals, formation of reactive oxygen species (ROS) and subsequently oxidative damage to lipids, proteins and DNA in exposed organisms. Thus, in the present study, effects and modes of action (MoA) have been investigated in D. magna exposed to gamma radiation (dose rates: 0.41, 1.1, 4.3, 10.7, 42.9 and 106 mGy/h) after short-term exposure (24 and 48 h). Several individual, cellular and molecular endpoints were addressed, such as ROS formation, lipid peroxidation, DNA damage and global transcriptional changes. The results showed that oxidative stress is one of the main toxic effects in gamma radiation exposed D. magna, mediated by the dose-dependent increase in ROS formation and consequently oxidative damage to lipids and DNA over time. Global transcriptional analysis verified oxidative stress as one of the main MoA of gamma radiation at high dose rates, and identified a number of additional MoAs that may be of toxicological relevance. The present study confirmed that acute exposure to gamma radiation caused a range of cellular and molecular effects in D. magna exposed to intermediate dose rates, and highlights the need for assessing effects at longer and more environmentally relevant exposure durations in future studies.

De Novo Development of a Quantitative Adverse Outcome Pathway (qAOP) Network for Ultraviolet B (UVB) Radiation Using Targeted Laboratory Tests and Automated Data Mining

“…magna after 2 days of exposure, according to the established method. , Fluorometric measurements of cellular ROS (cROS, n = 3), mitochondrial ROS (mROS, n = 3), and lipid peroxidation (LPO)-associated ROS (lpoROS, n = 3) in D. magna after 2 days of exposure were performed using the probes 2′,7′-dichlorodihydrofluorescein diacetate (H 2 DCFDA), dihydrorhodamine 123 (DHR123) and 4,4-difluoro-3a,4adiaza-s-indacene (BODIPY), respectively, as previously described. , 8-Oxo-2′-deoxyguanosine (8-OHdG) was used as a biomarker to indicate oxidative DNA damage in D. magna after 2 days of exposure to UVB.…”

Gamma Radiation Induced Changes in the Biochemical Composition of Aquatic Primary Producers and Their Effect on Grazers

“…Eustigmatophyceae, such as E. magnus, are known to be rich in PUFAs and are therefore regarded as high-quality food for zooplankton, while Chlorophyceae, such as R. subcapitata, generally lack PUFAs and are therefore regarded as poorer quality food (Lang et al, 2011). Additionally, R. subcapitata serves as a model species in many ecotoxicology studies and has been used in effect studies of È-radiation and effects of radionuclide exposure (Neves et al, 2015;; (Gomes et al, 2018).…”

Assessing relative biomarker responses in marine and freshwater bivalve molluscs following exposure to phosphorus 32 (32P): Application of genotoxicological and molecular biomarkers

“…given that the earliest observable signs of biological stress can be transcriptional alteration of the genes (Bahrami and Drabløs, 2016). To date, there is limited information available on IR induced mRNA alterations in aquatic invertebrates (Gomes et al, 2018;Han et al, 2014a, b;Farcy et al, 2007Farcy et al, , 2011AlAmri et al, 2012;Devos et al, 2015;Dallas et al, 2016). More studies are required, particularly as most of the information available in the literature have evaluated expression of genes and other biological responses following exposure of organisms to acute, external radiation sources (i.e.…”