Complex Toxicity Of Metal And PFOS Or PFOA On Cynoglossus Semilaevis Liver Cells

Perfluorooctane sulfonate（PFOS） and perfluorooctanoic acid（PFOA） are commonly used in industrial production. It is also a common pollutant in the water, which is highly toxic to aquatic organisms. Copper and cadmium are another important pollutants in the water environment, and the heavy metals are easy to be enriched in organisms, which cause chronic toxicity to aquatic organisms. In the water environment, heavy metals and PFCs have the potential to coexist, and the biological effects of PFCs on the transformation, metabolism and toxicity of the organisms may be affected by the coexistence of heavy metals. Therefore, it is of great significance to study the joint toxicity effects of two kinds of pollutants on aquatic organisms. In this study, the typical nearshore marine fish cynoglossus semilaevis liver cells（HTLC） were used as the experimental object, the experiment studied PFOS/PFOA, Cu²⁺ and Cd²⁺ single and combined exposure conditions cell viability and cell injury situation, and analyzed the changes in the content of hydroxyl radical（OH-） and metal sulfur protein（MT）, the complex toxicity effect and its mechanism of PFOS/PFOA, Cu²⁺ and Cd²⁺ on HTLC were studied from the molecular level.The acute toxicity test results of PFOS/PFOA, Cu²⁺, Cd²⁺ on HTLC showed that the half inhibition rate（IC50） value of these four kinds of chemicals were 322.22 uM、583.46 uM、341.26 uM and 72.42 uM. The single effect of 100⁷00 uM PFOS/PFOA, 25⁶30 uM Cu²⁺ and 10¹00 uM Cd²⁺ has a significant inhibitory effect on HTLC（p<0.05）. After the combined effects of ≤600 μM PFOS/PFOA and Cu²⁺, the cell metabolism was enhanced and the cell proliferation was promoted. However, 500 μM PFOS/PFOA and 100 μM Cd²⁺ significantly inhibited cell proliferation（p<0.05）. The results of electron microscope showed that the cell membrane system of 500 μM PFOS/PFOA and 100 μM Cd²⁺ were damaged, and the mitochondria and endoplasmic reticulum were edema. Meanwhile, the rate of abnormal nucleus was increased, and the apoptosis and even death occurred. After the compound action of 300⁵00 uM PFOS/PFOA and Cu²⁺ or 32 μM Cd²⁺, HTLC OH· content increased, PFOS/PFOA and 100 μM Cd²⁺ can significantly inhibited the OH· produced（p<0.05）, and the complex toxicity effects and cell oxidative damage related. After the compound action of PFOS/PFOA and Cu²⁺ or 32 μM Cd²⁺, HTLC MT content increased, and the compound action of 500 uM PFOS/PFOA and 100 uM Cd²⁺, MT expression was inhibited（P < 0.05）, the combined toxicity effects and metal detoxification capacity. This study showed that PFOS/PFOA and high concentration of Cd²⁺ combined exposure toxicity of the enhancement may be due to the combined effect of PFOS/PFOA、Cd²⁺ caused the increase of cellular oxidative damage, cell activity decreased, organelles damage degree increases, OH· and MT content reduced, resulting in metal detoxification capacity decreased, cell death. In the end, the complex toxicity enhanced. This study provided a scientific basis for assessing the environmental risks of the two kinds of pollutants.