Transcriptomic Insights into Post-Spawning Death and Muscle Atrophy in Ayu (Plecoglossus altivelis)

Area of Science:

• Molecular Biology
• Fish Physiology
• Genomics

Background:

• Semelparous species, such as ayu (Plecoglossus altivelis), exhibit post-spawning mortality.
• The molecular underpinnings of this rapid physiological decline and death are not well understood.

Purpose of the Study:

• To investigate transcriptomic alterations in ayu skeletal muscle before and after spawning.
• To identify key genes and pathways involved in post-spawning muscle atrophy and metabolic dysfunction.

Main Methods:

• RNA sequencing was employed to analyze gene expression profiles.
• Differential Gene Expression (DEG) analysis, Gene Set Enrichment Analysis (GSEA), KEGG pathway analysis, and Protein-Protein Interaction (PPI) network analysis were performed.

Main Results:

• Over 3000 differentially expressed genes (DEGs) were identified.
• Significant downregulation of energy metabolism and protein degradation pathways was observed.
• Post-spawning ayu showed decreased body weight, reduced myosin heavy chain gene expression, and signs of muscle atrophy.
• Decreased expression of AP-1 transcription factors and the identification of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) as a key factor in muscle atrophy and aging were noted.

Conclusions:

• Ayu skeletal muscle undergoes severe metabolic disorders and cellular stress responses post-spawning.
• These molecular changes provide insights into the mechanisms driving post-spawning death in ayu.
• GAPDH may play a critical role in the accelerated aging and muscle atrophy observed.