Development of a non-lethal method for evaluating transcriptomic endpoints in Arctic grayling (Thymallus arcticus)

Area of Science:

• Environmental Science
• Molecular Biology
• Ecotoxicology

Background:

• Mining activities in the Canadian Yukon pose risks to watershed health.
• Existing environmental assessments use non-Arctic sentinel species, limiting their effectiveness.
• There is a need for Arctic-specific, non-lethal monitoring methods.

Purpose of the Study:

• To develop a quantitative real-time polymerase chain reaction (qPCR) assay for Arctic grayling (Thymallus arcticus).
• To evaluate the feasibility of using non-lethal caudal fin sampling for mRNA analysis.
• To assess mRNA profiles as indicators of environmental conditions, specifically metal contamination.

Main Methods:

• Developed a qPCR assay targeting Arctic grayling (Thymallus arcticus).
• Collected non-lethal caudal fin and liver tissue samples from fish in contaminated and reference sites.
• Measured mRNA abundance of metallothionein (mta/mtb), heat shock protein 70 (hsp70), and catalase (cat) genes.
• Assessed fish condition factor and body burdens of cadmium (Cd), zinc (Zn), and lead (Pb).

Main Results:

• Fish from the contaminated site showed lower condition factor.
• Elevated hepatic and caudal fin metallothionein (mta/mtb) mRNA abundance was observed in fish from the test site.
• Liver samples revealed increased heat shock protein 70 (hsp70) and catalase (cat) mRNA levels.
• A strong positive correlation existed between metal body burden and caudal fin mta/mtb mRNA.

Conclusions:

• The developed qPCR assay is effective for monitoring Arctic grayling health.
• Non-lethal caudal fin sampling is a viable method for environmental assessment.
• The Arctic grayling assay shows high potential for non-lethal environmental monitoring of mining impacts in the Yukon.