Endocrine disruptor responses in the embryos of marine medaka (Oryzias melastigma) after exposure to aged plastic leachates

The issue of the additives leached from plastics has attracted widespread attention. More crucially, endocrine disruptor status for several leached additives has been established. However, little is known about the overall endocrine disrupting effects of aged plastic leachates. Therefore, the transcriptional responses of endocrinerelated genes were assessed in the embryos of marine medaka (Oryzias melastigma), which were exposed to the leachates from aged plastics that were immersed into the simulated seawater (SW) or fish digest (FD). The results revealed that there was a great difference between the SW and FD leachates in the transcripts of endocrine-related genes. With the exception of cyp1a, all target genes had their transcripts potentially downregulated by the FD leachates. Chgl (a biomarker for estrogens), ppar & beta; (related to lipid metabolism), and cyp19a (related to sexual differentiation and reproduction) transcripts tended to be repressed by the SW leachates, while ppar & alpha;, ppar & gamma; and cyp1a (mediating metabolism of xenobiotics) transcripts were stimulated. In addition, a redundancy analysis was carried out to determine the relationship between the leached additives and the transcriptional changes. However, the additives only partially explained the variation in the transcripts of endocrine-related genes (24.8%), indicating that other leached additives may have an impact on target gene transcription. This study provided molecular evidence of the aged plastic leachates' endocrine disrupting effects. Exploring the primary factors that affect the transcriptional alterations would require more research.

Automated summary

The issue of additives leached from plastics and their endocrine disrupting effects have attracted attention. This study assessed the transcriptional responses of endocrinerelated genes in marine medaka embryos exposed to leachates from aged plastics immersed in simulated seawater or fish digest. The results showed significant differences in gene transcripts between the two types of leachates, and other leached additives may also impact gene transcription. This study provides molecular evidence of the endocrine disrupting effects of aged plastic leachates and calls for further research on the primary factors affecting transcriptional alterations.