Histopathological and ultrastructural alterations reveal the toxicity of particulate matter (PM2.5) in adult zebrafish

Abstract

The exposure of fine particulate matter (PM2.5) can lead to developmental toxicity in organs. However, the underlying specific mechanisms are still unclear. Especially, the toxic effects of PM2.5 on adult zebrafish are still obscure. In this study, for the first time, the toxic effects of PM2.5 on zebrafish (Danio rerio) as well as the changes in cellular and subcellular traits of multi-organs were investigated. The treatment groups were exposed to 100 mg/L PM2.5 for 5 days. The pathological and ultrastructural changes in multi-organs of the treatment and control (without PM2.5) groups were subsequently examined. As a result, histopathological alterations were obviously noted the exposed multi-organs (gill, liver, intestine, heart and gonads) of adult zebrafish. Especially, marked changes were observed after the exposure of PM2.5 in intestine images of X-ray micro CT. In addition, when typical ultrastructural arrangements of multi-organs (gill, liver and intestine) were examined, their contours were unclear, and organelles were dissolved, necrotized and almost degenerated in the treated zebrafish group. These adverse effects of PM2.5 on multi-organs might raise a potential concern for zebrafish development and reproduction. Furthermore, these multi-organ alterations could be used as a sensitive biomarker in the toxicity assessment of PM2.5. In addition, the present results would be useful for better understanding of PM2.5-induced toxicity to organisms, and the cellular and subcellular impairments in multi-organs may affect aquatic organisms.