Lead and lead–arsenic combined exposure induces mortality and developmental impairments in zebrafish embryos: a study using wild-caught zebrafish from Bangladesh

Abstract

Heavy metal toxicity has become a global health burden, exerting various physiological effects on aquatic animals and humans. Zebrafish (Danio rerio) has emerged as a real-time model system for toxicological study. We previously reported the effects of arsenic on the embryonic development of zebrafish. The current study aimed to get deep insights into the toxic effects of another heavy metal, lead, on the early embryonic development of wild-caught zebrafish. We exposed freshly collected zebrafish embryos to different lead concentrations and studied different developmental and morphological changes using an inverted microscope. In a separate experiment, embryos were exposed to a combination of lead and arsenic to evaluate the combined effects of the elements. Lead concentration of as low as 0.25 mM resulted in developmental and morphological abnormalities in the zebrafish embryos. Exposure to different concentrations (0.25 mM, 0.5 mM, and 0.75 mM) caused a higher mortality rate of the embryos. Besides, an increased rate of arrested hatching, irregularities in size and shape of the yolk sac, deformed otic vesicle, and body curvature were observed in a dose-dependent manner. Lead exposure also resulted in reduced heart rate and severe pericardial edema. The combined effect of minimum concentrations of lead and arsenic that causes toxicity individually (0.25 mM and 1.0 mM, respectively) revealed a more severe effect than the individual treatments. This study's findings explain the association of heavy metal exposure with an increased rate of miscarriage/abortion incidences in highly polluted areas assisting in proper management and creating public awareness.

Keywords:

• Lead
• zebrafish
• embryonic development
• mortality
• lead–arsenic combined effect

Acknowledgements

The authors wholeheartedly acknowledge Prof. Golam Rabbane (Department of Fisheries, University of Dhaka) for supplying wild-caught zebrafish models. Also, we thank Mr. Jakir Hossain (Department of Fisheries and Oceanography, Sher-e-Bangla Agricultural University) for his unconditional help. We sincerely appreciate Ms. Jarin Taslem Mourosi for taking care of and maintaining the zebrafish facility lab during the course of this study.

Ethics approval and consent to participate: The Institutional Ethical Committee, School of Life Sciences and School of Agriculture and Mineral Sciences, Shahjalal University of Science & Technology, Sylhet 3114, Bangladesh critically reviewed the protocols and approved this study (reference: LS-07-29-19).

Author contributions

NJ: investigation, data curation, formal analysis, validation, writing – original draft. SA: investigation, methodology, validation, formal analysis, software, visualization, writing – original draft, writing – review and editing. TK: investigation, formal analysis. MH: conceptualization, methodology, resources, supervision, project administration, funding acquisition.

Disclosure statement

The authors declare that they have no competing interests.

Data availability statement

All data are provided with the manuscript.

Additional information

Funding

MH received grant supports from the University Grant Commission (UGC) of Bangladesh (Grant ID: Med-17/2016/6467) and the Research Center, Shahjalal University of Science and Technology (Grant ID: LS-2017/06).