Copper-induced oxidative stress inhibits asexual reproduction of Aurelia coerulea polyps

Objective: Our research aims to investigate the specific mechanisms by which copper inhibits the asexual proliferation of Aurelia coerulea polyps. Methods: Aurelia coerulea polyps were exposed to various CuSO4 concentrations to study metamorphosis and budding proliferation. Oxidative stress markers (ROS, MDA, CAT, H2O2, T-AOC, SOD) were measured in polyps and early strobilae. Transcriptomic analysis were used to compare differences in gene expression and enrichment pathways between untreated and copper-exposed polyps. Additionally, RT-qPCR was used to analyze the expression of key molecules. Antioxidant L-Ascorbic acid was applied to determine the role of oxidative stress in asexual reproduction of Aurelia coerulea polyps when exposed to copper. Results: Copper inhibited strobilization and budding of Aurelia coerulea polyps in a dose-dependent manner, in which oxidative stress was involved. Transcriptomic data suggested that the DNA replication pathway was significantly enriched in early strobilae compared to polyps. However, copper treatment repealed the difference of DNA replication pathway between early strobilae compared and polyps. Transcriptomic data suggested that alanine, aspartate, and glutamate metabolism pathways were enriched in untreated budding polyps compared to copper-exposed polyps. After applying the antioxidant L-Ascorbic acid to copper-exposed polyps, various oxidative indicators changed to different extents, with increases in ROS, MDA, CAT, H2O2, and SOD and a decrease in T-AOC. Further more, the time required for polyps to develop into early strobila was shortened, indicating that the delay in metamorphosis caused by copper exposure was effectively alleviated. And the budding rate increased, indicating that the inhibition of budding proliferation caused by copper exposure was effectively alleviated. The expression of key genes were consist with the transcriptomic sequencing results. Conclusion: Copper exposure causes oxidative stress resulting in the inhibition of asexual reproduction in Aurelia coerulea polyps, including metamorphosis and budding.