Histopathological changes in zebrafish exposed to sublethal concentrations of 89 nm silver nanoparticles for application in environmental diagnostics

Abstract

The use of biomarkers as indicators of environmental contamination has been shown to be an excellent indicator of changes in biota. Histopathological lesions are commonly used in biomonitoring studies as they provide information regarding both acute and chronic exposure. The use of nanoparticle materials has been widespread in recent years. However, not much is known about their ecological effects on the natural environment. Thus, the aim of this study was to assess the sublethal effects of silver nanoparticles (AgNP) with mean diameters of 89 nm in the zebrafish Danio rerio by the determination of the LC₅₀; 48 h and histopathological assays in gills. The obtained LC₅₀; 48 h was 8.18 µgL⁻¹. The histopathological gill assessment showed primary responses indicative of acute damage as aneurysms (32.76%), hyperplasia (20.69%) and partial (30.17%) and total lamellar fusion (6.9%) of secondary lamellae. No deposition of AgNP was observed in any tested sample gills, suggesting other organs target to absorption and detoxification. In fact, the AgNP causes sublethal damage in the gills of zebrafish but is not able to accumulate in this tissue. Finally, the data shown in this study contribute to the construction of a database on the AgNP exposure in aquatic organisms.

Keywords:

• biomarkers
• Danio rerio
• environmental health
• gills
• deposition

Acknowledgments

The authors would like to thank the Mr Jonny Ross from Khemia for the donation of AgNP sample. The Institute of Energy and Nuclear Research and the Federal University of São Paulo for supporting this research. The Laboratory of Ecology of Reproduction and Recruitment of Marine Organisms-Oceanography Institute of University of São Paulo (ECORREP-IO/USP) by the use of the microtome and microscope required to process the histological samples.

Compliance with ethical standard

Rogero J. S. and Rogero S. O. have received research grants from the Institute of Energy and Nuclear. The authors declares that they has no conflict of interest. All organisms used during this study were collected and treated in accordance with the rules issued by the National Council for Control of Animal Experimentation (CONCEA)/Brazil, and was approved by the Ethic Committee on Animal Use of the Federal University of Sao Paulo, Brazil (CEUA/UNIFESP), registered by the protocol number CEUA 7854090614. This article does not contain any studies with human participants performed by any of the authors.