Photoaged
Polystyrene Nanoplastics Result in Transgenerational
Reproductive Toxicity Associated with the Methylation of Histone H3K4
and H3K9 in Caenorhabditis elegans
posted on 2023-11-07, 19:34authored byHaibo Chen, Yulun Gu, Yongqi Jiang, Jun Yu, Chao Chen, Chongli Shi, Hui Li
Polystyrene
nanoplastics (PS-NPs) are emerging environmental contaminants
that are ubiquitously detected in various environments and have toxic
effects on various organisms. Nevertheless, the transgenerational
reproductive toxicity and underlying mechanisms of PS-NPs remain largely
unknown, especially for photoaged PS-NPs under ultraviolet irradiation.
In this study, only the parental generation (P0) was exposed to virgin
and aged PS-NPs at environmentally relevant concentrations (0.1–100
μg/L), and subsequent generations (F1–F4) were cultured
under normal conditions. Ultraviolet irradiation induced the generation
of environmentally persistent free radicals and reactive oxygen species,
which altered the physical and chemical characteristics of PS-NPs.
The results of toxicity testing suggested that exposure to aged PS-NPs
caused a more severe decrease in brood size, egg ejection rate, number
of fertilized eggs, and hatchability than did the virgin PS-NPs in
the P0, F1, and F2 generations. Additionally, a single maternal exposure
to aged PS-NPs resulted in transgenerational effects on fertility
in the F1 and F2 generations. Increased levels of H3K4 and H3K9 methylation
were observed in the F1 and F2 generations, which were concomitant
with the transgenerational downregulation of the expression of associated
genes, such as spr-5, set-17, and met-2. On the basis of correlation analyses, the levels
of histone methylation and the expression of these genes were significantly
correlated to transgenerational reproductive effects. Further research
showed that transgenerational effects on fertility were not observed
in spr-5(by134), met-2(n4256), and set-17(n5017) mutants. Overall, maternal exposure to aged
PS-NPs induced transgenerational reproductive effects via H3K4 and
H3K9 methylation, and the spr-5, met-2, and set-17 genes were involved in the regulation
of transgenerational toxicity. This study provides new insights into
the potential risks of photoaging PS-NPs in the environment.