Sublethal effects of methylmercury on lateral line sensory and ion-regulatory functions in zebrafish embryos.

Giun-Yi Hung, Yu-Chin Pan, Jiun-Lin Horng, Li-Yih Lin

Comparative biochemistry and physiology. Toxicology & pharmacology : CBP 2023 Sep

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Methylmercury can interfere with the normal functioning of the nervous system, causing a variety of behavioral and physiological changes in fish. However, the influence of MeHg on the lateral line sensory and ion-regulatory functions of fish is not clear. Zebrafish embryos were utilized as a model to address this question. After exposure to water-borne MeHg (5, 10, 50, or 100 ppb) for 96 h (4-100 h post-fertilization), the survival rate declined by ca. 50 % at 100 ppb. However, MeHg at sublethal concentrations delayed hatching and decreased heart rates and body length. As to effects on the lateral line sensory system, MeHg at ≥10 ppb decreased the number of hair cells and impaired hair bundles and Ca2+-mediated mechanical transduction. As to ion regulation, MeHg at ≥10 ppb decreased the densities of skin stem cells and ionocytes, leading to declines in ion (Na+, K+, and Ca2+) contents and H+/NH4+ excretion levels. A gene expression analysis also revealed declines in messenger RNA levels of several ion-regulatory genes (ncc2b, trpv6v1a, trpv5/6, ncx1b, and rhcg1). This study demonstrated that the lateral line sensory and ion regulatory functions of fish are extremely sensitive to MeHg. Copyright © 2023 Elsevier Inc. All rights reserved.

Citation

Giun-Yi Hung, Yu-Chin Pan, Jiun-Lin Horng, Li-Yih Lin. Sublethal effects of methylmercury on lateral line sensory and ion-regulatory functions in zebrafish embryos. Comparative biochemistry and physiology. Toxicology & pharmacology : CBP. 2023 Sep;271:109700