Innovative transgenic zebrafish biosensor for heavy metal detection.

Area of Science:

• Environmental Science
• Biotechnology
• Toxicology

Background:

• Heavy metal contamination poses significant risks to ecosystems and human health.
• Developing sensitive and specific biosensors is crucial for effective environmental monitoring.
• Zebrafish offer a viable model organism for toxicity and biosensing studies.

Purpose of the Study:

• To engineer zebrafish as biosensors for detecting cadmium (Cd²⁺) and zinc (Zn²⁺).
• To evaluate the biosensor's sensitivity, specificity, and detection limits for heavy metals.
• To assess the toxicity of heavy metals on zebrafish early developmental stages.

Main Methods:

• Synthesized a novel heavy metal-sensitive gene construct (metallothionine 2 promoter with DsRed reporter gene).
• Integrated the construct into zebrafish embryos using a Tol2 transposon transposase system.
• Applied the transgenic zebrafish line for biosensing Cd²⁺ and Zn²⁺ and assessed toxicity via a modified OECD Fish Embryo Toxicity test.

Main Results:

• The mt2-DsRed2 zebrafish biosensor demonstrated a linear correlation between heavy metal concentration and DsRed fluorescence for Cd²⁺ and Zn²⁺ (p < 0.01).
• Achieved a minimum detection limit of 4 ppb for Cd²⁺ and Zn²⁺, with no cross-reactivity to Ni²⁺.
• Cd²⁺, Zn²⁺, and Ni²⁺ showed no significant toxicity to zebrafish embryos at concentrations up to 10 ppb.

Conclusions:

• The developed transgenic zebrafish line serves as an accurate and specific biosensor for low-concentration Cd²⁺ and Zn²⁺.
• This biosensor is suitable for laboratory-based heavy metal assessment assays and environmental monitoring.
• The findings confirm the biocompatibility of the transgenic zebrafish for heavy metal sensing applications.