Prevention of La^3＋ on DNA Damage Caused by Hg^2＋ from Fish Intestines

Recent studies have shown that heavy metals havebecome the most important contaminants in the environ-ment.Some heavy metals ,such as Pb, Cd, Hg, As ,Co,and Cr have genetic toxicity. They disturb DNAmetabolismand lead to aberrance of chromosome andDNA1].…

Prevention of La on DNA Damage Caused by Hg from Fish Intestines

The aim of this study was to investigate the effects of rare earth elements (REEs) in preventing Hg²⁺ pollution, using fish intestinal DNA in vitro and study the mechanism of the interactions between Hg²⁺, La³⁺, the mixture of La³⁺ and Hg²⁺ and DNA by spectroscopy. The interactions between Hg²⁺, La³⁺, the mixture of La³⁺ and Hg^2- and DNA from fish intestine in vitro was investigate by using absorption spectrum and fluorescence emission spectrum. Ultraviolet absorption spectra indicated that the addition of Hg²⁺, La³⁺, and the mixture of La³⁺ and Hg²⁺ to DNA generated obvious hypochromic effect. Meanwhile, the 205.2 nm peak of DNA blue and the 258.2 nm peak of DNA red shifted. The hypochromic effect and peak shift was caused by these ions in an order of Hg²⁺ > Hg²⁺ + La³⁺ > La^3-. The fluorescence emission spectra showed that as the addition of Hg²⁺, La³⁺, and the mixture of La³⁺ and Hg²⁺. the emission peak at about 416.2 nm of DNA did not obviously change, but the fluorescence intensity reduced gradually with the order in treatment was Hg²⁺ > Hg²⁺ + La³⁺ > La³⁺. Hg²⁺, La³⁺, and the mixture of La³⁺ and Hg²⁺ had 1.12, 0.58, and 0.81 binding sites to DNA, the fluorescence quenching of DNA caused by them all attributed to static quenching. The binding constants K_A of binding sites were 3.82 × 10⁴ and 4.22 × 10² L·mol⁻¹; 2.50 × 10⁴ and 2.95 × 10³ L·mol⁻¹; 3.05 × 10⁴ and 1.00 × 10³ L·mol^−1. The results showed that La³⁺ could relieve destruction caused by Hg²⁺ on the DNA structure.