Multifunctional murrel caspase 1, 2, 3, 8 and 9: Conservation, uniqueness and their pathogen-induced expression...

Area of Science:

• Molecular Biology
• Fish Immunology
• Protease Function

Background:

• Caspases are crucial proteases regulating apoptosis and inflammation.
• Epizootic Ulcerative Syndrome (EUS), caused by Aphanomyces invadans and secondary bacterial infections, devastates striped murrel (Channa striatus) populations.
• Understanding caspase roles is vital for managing fish diseases and economic losses.

Purpose of the Study:

• To analyze the physicochemical and structural characteristics of five striped murrel caspase genes (CsCasp 1, 2, 3, 8, and 9).
• To investigate the tissue distribution of these caspase genes in C. striatus.
• To examine the expression patterns of caspase genes following fungal and bacterial infections to elucidate their roles in disease response.

Main Methods:

• Physicochemical and structural analysis of cDNA and protein sequences of five C. striatus caspases.
• Tissue distribution analysis of caspase gene expression in immune organs.
• Gene expression analysis of caspases after experimental induction of fungal (Aphanomyces invadans) and bacterial (Aeromonas hydrophila) infections.

Main Results:

• Murrel caspases exhibit conserved CASC domains but possess unique features, suggesting functional diversity.
• All five caspase genes are highly expressed in key immune tissues like liver, kidney, spleen, and blood cells.
• Caspase gene expression peaked at 24 hours post-infection for bacterial and 48 hours for fungal infections, with varied initiation times indicating distinct roles (pro-inflammatory, initiator, executioner).

Conclusions:

• Striped murrel caspases display structural and functional diversity.
• These caspases are integral components of the immune response in C. striatus, with differential activation patterns against specific pathogens.
• The findings provide insights into the molecular mechanisms of fish immunity and disease pathogenesis.