Inconsistent transcriptomic responses to hexabromocyclododecane in Japanese quail: a comparative analysis of results...

Area of Science:

• Environmental Toxicology
• Genomics
• Chemical Safety Assessment

Background:

• Transcriptomics is increasingly used in New Approach Methods (NAMs) for toxicity testing.
• Classical toxicity testing relies on consistent, characteristic transcriptomic signatures.
• Comparative analysis of transcriptomic responses across different methodologies is crucial for regulatory acceptance.

Purpose of the Study:

• To investigate the consistency of transcriptomic responses to hexabromocyclododecane (HBCD) across different exposure scenarios and life stages in Japanese quail.
• To evaluate the comparability of transcriptomic data generated by various test methodologies, including a NAM.

Main Methods:

• Japanese quail (Coturnix japonica) were exposed to sublethal doses of HBCD via egg injection (early-life stage), oral gavage (adult), and maternal transfer with dietary exposure (early-life stage and nestling).
• Differential gene expression analysis was performed on liver tissues from four distinct exposure studies.
• The number of differentially expressed genes (DEGs) and shared DEGs between studies were compared.

Main Results:

• A variable number of DEGs were detected across the four studies (ranging from 3 to 550).
• Only 19 DEGs were common between the two studies with the most significant findings (Study 1 and Study 2).
• Factors such as dose, exposure route, life stage, sampling time, and chemical composition influenced transcriptomic responses.

Conclusions:

• Transcriptomic responses to HBCD are not consistently conserved across different test methodologies and life stages in Japanese quail.
• Significant challenges exist in comparing transcriptomic data generated by diverse experimental designs.
• Further research is needed to understand and standardize transcriptomics-based toxicity testing for regulatory applications.