Copper Toxicity and Calcium Supplementation on nkx2.5 and mt2 Gene Expression in Zebrafish Embryos
Sahib Mohammad bakir 1*, Theodore B. Henry 2, Richard D. Handy 3
Journal of Angiotherapy 8(4) 1-9 https://doi.org/10.25163/angiotherapy.849516
Submitted: 29 February 2024 Revised: 02 April 2024 Published: 04 April 2024
This study determined how copper toxicity and calcium supplementation affect gene expression in early zebrafish embryos to inform aquatic environmental health and developmental biology.
Abstract
Background: Heavy metals are pervasive pollutants in aquatic ecosystems, posing significant threats to the survival and development of aquatic organisms, particularly during their early life stages. These pollutants have the capacity to interfere with the expression of critical genes involved in organogenesis and physiological processes essential for embryonic development, including water balance and electrolyte regulation in fish. While copper is necessary for fish growth and maturation, elevated levels of dissolved copper in water can lead to adverse effects on early developmental stages. The aim of this study was to evaluate the expression pattern of the nkx2.5 gene throughout various phases of embryonic development and investigate the impact of dissolved copper (Cu) toxicity on cardiac development. Additionally, the study aimed to explore the potential of Mt2 expression as a biomarker for metal toxicity. Methods:
The study assessed the expression levels of the nkx2.5 gene at different time points during embryonic development, focusing particularly on its peak expression time. Zebrafish embryos were exposed to dissolved copper, either alone or in combination with calcium (Cu+Ca), to examine the effects on nkx2.5 expression. The expression of Mt2, a potential marker for metal toxicity, was also analyzed under copper exposure conditions. Results: The experimental results revealed that nkx2.5 gene expression peaked at 16 hours post-fertilization (hpf), a critical time period for heart formation and development in zebrafish embryos. Exposure to both copper and calcium (Cu+Ca) significantly increased nkx2.5 expression by nearly tenfold compared to control conditions or exposure to copper alone. Furthermore, the expression of Mt2 showed a substantial sixfold increase under copper exposure conditions in the absence of additional calcium (Ca2+), indicating metal-induced stress. Conclusion: The findings of this study underscore the heightened susceptibility of zebrafish embryos to metal exposure during early developmental stages. Metal exposure during these critical periods leads to disruptions in cellular biology, particularly in heart development, impacting the survival and health of fish. The study highlights the importance of understanding the temporal dynamics of metal toxicity in embryonic development for effective environmental management and conservation efforts.
Keywords: Zebrafish, Heavy metals, Embryonic development, nkx2.5 gene expression, Copper toxicity, Mt2 biomarker, Calcium.
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