Effects of Microcystis aeruginosa on the expression of nuclear receptor genes in Daphnia similoides sinensis

Nuclear receptor (NR) genes form a conserved superfamily, which is involved in organism metabolism, reproduction, development, homeostasis, and resource allocation. Microcystis aeruginosa can inhibit the growth and reproduction of Daphnia. However, whether M. aeruginosa can affect the expression of Daphnia NR genes is unknown. In total, 18 NRs were identified in this study based on previous Daphnia similoides sinensis transcriptome data. In treatments containing M. aeruginosa, the gene expression of the NR1 subfamily (E75a, E75b, HR3, HR96, NHR-1, HR97a, HR97g, and NHR97) and the NR2 subfamily (RXR, TLL, PNR, and SVP) were down-regulated 59% and 79%, respectively. In treatments containing M. aeruginosa, although the expression of 78% of the genes showed a similar trend in clones 1 and 2, the expression of 42% of the genes in clone 3 showed the opposite trend compared to clones 1 and 2, suggesting that the adaptability and molecular mechanism differ in individuals with different Microcystis tolerance genotypes.