Parental transfer of titanium dioxide nanoparticle aggravated MCLR-induced developmental toxicity in zebrafish offspring†
This work focuses on the transgenerational effects of titanium dioxide nanoparticles (n-TiO2) and microcystin-LR (MCLR) on the development of F1 zebrafish offspring. Wild-type adult zebrafish (4 months old) were exposed to various MCLR concentrations (0, 0.5, 4, and 32 μg L−1) with and without n-TiO2 (100 μg L−1) for 45 days. F1 zebrafish embryos from the above-mentioned parents were collected and cultured in clean water for 120 hours post-fertilization (hpf). Our results showed that n-TiO2 could potentially be transferred from parents to offspring, which further led to the increase in the accumulation of MCLR content in F1 zebrafish embryos. Hypoactivity and indistinct retinal layers in F1 larvae were observed, and the presence of n-TiO2 intensified these adverse effects in co-exposure groups. The parental transfer of MCLR and n-TiO2 further increased the formation of reactive oxygen species (ROS) in F1 larvae, which contributed to more apoptotic cells in and around the eyes of F1 larvae. Furthermore, we detected altered gene expression (p53, Bax, Bid, Bcl-2, puma, and Apaf-1), protein expression (P53, Bax, Bcl-2, and cytochrome c) and enzyme activities (caspase-3, caspase-8, and caspase-9), indicating that parental transfer of n-TiO2 could aggravate MCLR-induced apoptosis in F1 offspring through the mitochondria-mediated apoptosis pathway. In summary, this research studied the bioaccumulation, parental transfer, and developmental toxicity of MCLR and n-TiO2 to examine their interactions, revealing that the health risks of co-exposure should not be ignored.