Multigenerational Effects of Graphene Oxide Nanoparticles on Acheta domesticus DNA Stability

Abstract

The use of nanoparticles like graphene oxide (GO) in nanocomposite industries is growing very fast. There is a strong concern that GO can enter the environment and become nanopollutatnt. Environmental pollutants' exposure usually relates to low concentrations but may last for a long time and impact following generations. Attention should be paid to the effects of nanoparticles, especially on the DNA stability passed on to the offspring. We investigated the multigenerational effects on two strains (wild and long-lived) of house cricket intoxicated with low GO concentrations over five generations, followed by one recovery generation. Our investigation focused on oxidative stress parameters, specifically AP sites (apurinic/apyrimidinic sites) and 8-OHdG (8-hydroxy-2'-deoxyguanosine), and examined the global DNA methylation pattern. Five intoxicated generations were able to overcome the oxidative stress, showing that relatively low doses of GO have a moderate effect on the house cricket (8-OHdG and AP sites). The last recovery generation that experienced a transition from contaminated to uncontaminated food presented greater DNA damage. The pattern of DNA methylation was comparable in every generation, suggesting that other epigenetic mechanisms might be involved.

Keywords: 8-OHdG; AP sites; DNA damage; DNA methylation; epigenetics; graphene oxide; invertebrate; multigenerational effects; nanotoxicity; oxidative stress.

Figure 1

Image of graphene oxide (a) SEM magnification: 10000x; scale bar 10 µm; (b) AFM.

Figure 2

Zeta potential of GO dispersion in water.

Figure 3

DNA stability parameters in the wild-type strain (H) of A. domesticus that had been chronically intoxicated with graphene oxide: (a) AP sites (apurinic/apyrimidinic sites); (b) 8-OHdG (8-hydroxy-2′-deoxyguanosine); (c) Global DNA methylation in the gut cells. Abbreviations: Generation 1–5 (G1–G5): Control animals fed uncontaminated food; lower and higher groups of animals fed GO-contaminated food at a concentration of 0.02 or 0.2 mg∙kg⁻¹ of dry food, respectively; G6—animals fed uncontaminated food; n = 5; the data were normalized using Box–Cox transformation; significant differences were measured using ANOVA (Fisher test; p < 0.05); different letters denote differences among the experimental groups in the generation.

Figure 4

DNA stability parameters in the long-lived strain (D) of A. domesticus that had been chronically intoxicated with graphene oxide: (a) AP sites (apurinic/apyrimidinic sites), (b) 8-OHdG (8-hydroxy-2′-deoxyguanosine), (c) global DNA methylation in the gut cells of the long-living strain (D). Abbreviations: in Figure 3. Different letters denote differences among the experimental groups in the generation.

Figure 5

Simplified scheme of oxidative damage in the cell. Hydroxyl radicals can cause damage to proteins, membranes, and DNA. The HO· attacks DNA and oxidized products are formed. Mostly 2′-deoxyguanosine (2′-dG) in reaction with hydroxyl radical leads to the formation of 8-hydroxy-2′-deoxyguanosine (8-OHdG) or its tautomer 8-oxo-7-hydro-2′-deoxyguanosine (8-oxodG). Both changes can be promutagenic. In the process of Base Excision Repair (BER), the 8-oxoguanine glycosylase (OGG1) enzyme can cut out and exchange damaged bases.

Figure 6

Principal component analysis (PCA) of the investigated DNA stability parameters: AP sites (pentagon), 8-OHdG (square), and global DNA methylation (circle) were analyzed in each strain and treatment group separately.

Figure 7

Scheme of the experimental model. See materials and methods (experimental model).