Developmental toxicity from exposure to various forms of mercury compounds in medaka fish (Oryzias latipes) embryos.

Wu Dong,Lixin Wei,David E. Hinton,Jie Liu,Yang Jingfeng,Melissa Chernick

doi:10.7717/peerj.2282

Abstract

This study examined developmental toxicity of different mercury compounds, including some used in traditional medicines. Medaka (Oryzias latipes) embryos were exposed to 0.001–10 µM concentrations of MeHg, HgCl2, α-HgS (Zhu Sha), and β-HgS (Zuotai) from stage 10 (6–7 hpf) to 10 days post fertilization (dpf). Of the forms of mercury in this study, the organic form (MeHg) proved the most toxic followed by inorganic mercury (HgCl2), both producing embryo developmental toxicity. Altered phenotypes included pericardial edema with elongated or tube heart, reduction of eye pigmentation, and failure of swim bladder inflation. Both α-HgS and β-HgS were less toxic than MeHg and HgCl2. Total RNA was extracted from survivors three days after exposure to MeHg (0.1 µM), HgCl2 (1 µM), α-HgS (10 µM), or β-HgS (10 µM) to examine toxicity-related gene expression. MeHg and HgCl2 markedly induced metallothionein (MT) and heme oxygenase-1 (Ho-1), while α-HgS and β-HgS failed to induce either gene. Chemical forms of mercury compounds proved to be a major determinant in their developmental toxicity.

Highlights

Mercury-based traditional medicines are an important consideration in public health of specific countries
While control mortality exceeded that of the 0.001 μM group, this was due to the loss of a single control individual (Table S2)
Numerous aquatic organisms have been studied with respect to the toxicity of mercury; most studies were focused on organic mercury (e.g., MeHg) (Liao et al, 2007; Cuello et al, 2012) and/or inorganic HgCl2 (Ismail & Yusof, 2011; Wang et al, 2011; Wang et al, 2013)

Summary

Introduction

Mercury-based traditional medicines are an important consideration in public health of specific countries. In traditional Indian Ayurvedic (Kamath et al, 2012), Chinese (Pharmacopeia of China, 2015) and Tibetan medicines (Chen et al, 2012; Kan, 2013; Li et al, 2014; Wu et al, 2016), mercuric sulfides are frequently included in the treatment of various disorders, with the result that health concerns for public safety are increasing (Liu et al, 2008; Kamath et al, 2012) This form of mercury, from the naturally occurring minerals, cinnabar and. This distinction is important because it is the total mercury content rather than specific chemical forms that are commonly used to assess risk of traditional medicines, and this approach may be inaccurate

Methods

Results

Discussion

Conclusion