Publication Abstract

Global genomic methylation in the liver and gonads of the three-spined stickleback (Gasterosteus aculeatus) after exposure to hexabromocyclododecane and 17-beta oestradiol

Global genomic methylation in the liver and gonads of the three-spined stickleback (Gasterosteus aculeatus) after exposure to hexabromocyclododecane and 17-beta oestradiol

S.O. Aniagu, T.D. Williams, Y. Allen, I. Katsiadaki and J.K. Chipman

Alteration of DNA methylation is a major epigenetic mechanism associated with the effects of nongenotoxic carcinogens. We evaluated the effects of hexabromocyclododecane (HBCD), 17-b oestradiol (E₂) and 5-aza 2’ deoxycytidine (5AdC) on global DNA methylation levels (5-methyl 2’ deoxycytidine) in the liver and gonads of the three-spine stickleback (Gasterosteus aculeatus). HBCD at 30ng and 300ng/L of water did not produce statistically significant differences in global genomic methylation in liver of female stickleback. On the other hand, the methylation inhibitor, 5-aza-2’-deoxycytidine, significantly lowered hepatic global methylation levels in these fish by 13% (p<0.05). The naturally occurring oestrogen, 17-b oestradiol (E₂) at 100ng/L also decreased global DNA methylation levels in female liver but this effect was not statistically significant. In contrast, both E₂ and 5AdC caused statistically significant (p<0.001 and p<0.01 respectively) global genomic hypermethylation in the gonads of male sticklebacks although the increase seen in the female gonads was not statistically significant. The male gonad effect though unexplained may potentially be an indirect response to hypomethylation in other tissues (such as the liver) and may have important implications regarding oestrogenic effects in fish. The contrasting effects of HBCD and E₂ on global DNA methylation in stickleback should contribute to the integrated risk assessment of these environmental chemicals.

Reference:

S.O. Aniagu, T.D. Williams, Y. Allen, I. Katsiadaki and J.K. Chipman (not yet published) Global genomic methylation in the liver and gonads of the three-spined stickleback (Gasterosteus aculeatus) after exposure to hexabromocyclododecane and 17-beta oestradiol. Environment International, 34; 310-317

S.O. Aniagu, T.D. Williams, Y. Allen*, I. Katsiadaki* and J.K. Chipman

Environment International, 34; 310-317