Abstract: Cerium (Ce) is the most abundant rare-earth element. Using RAPD-PCR (random amplified polymorphic DNA-PCR) and MSAP-PCR (methylation-sensitive amplified polymorphism-PCR), the effects of Ce on genomic DNA damage and DNA methylation in zebrafish (Daniorerio) were examined. The results showed that, after the fish was exposed to different concentrations of Ce³⁺ (0, 5, 10 and 20 μmol·L^-1) for 28 days, Ce³⁺ was mainly enriched in the liver (bioconcentration factors BCF: 5.49-9.33), followed by gill (BCF: 3.58-4.49) and muscle (BCF: 0.13-0.25). The results of RAPD-PCR showed that Ce³⁺ (>10 μmol·L^-1) could induce DNA damage in zebrafish livers. The results of MSAP-PCR showed that the change rates of total genomic DNA methylation of zebrafish livers caused by Ce³⁺ stress were 8.93% (CK), 9.12% (5 μmol·L^-1), 15.56% (10 μmol·L^-1), and 28.83% (20 μmol·L^-1), respectively. The demethylation (D) of genomic DNA in zebrafish livers significantly increased under the low concentration of Ce³⁺, while the methylation (M) significantly increased under the high concentration of Ce³⁺. Meanwhile, the methylation polymorphism increased with the increases of Ce³⁺ concentration. Results from sequencing analysis showed that these specific bands had high homo logy with the genes of zinc finger protein STZ/ZAT10, ABC transporter 1, and cell cycle control phosphatase superfamily protein. Compared to RAPD markers, DNA methylation markers were highly sensitive to Ce³⁺ stress. These results contribute to our understanding of the biological effects of rare earth elements.

Key words: nitrogen translocation, dryland wheat, water consumption, seeding rate, sowing date