Transcriptome Profiling of Tiger Pufferfish (takifugu Rubripes) Gills in Response to Acute Hypoxia

Hypoxia is thought to suppress the immune response and lead to severe mortality of marine organisms. In recent years, hypoxic stress has become a serious problem in Takifugu rubripes culture due to the increase in culture density. Gills, as the primary organ of physiological exchange with the surrounding environment, play a key role in the response of fish facing hypoxic stress. To understand the biological processes and complex molecular mechanisms of hypoxia in T. rubripes, we performed a transcriptomic analysis of hypoxic stress in the gills of T. rubripes. Twenty-four healthy fish weighing 461.75 +/- 40.66 g were randomly divided into four groups according to oxygen concentration. [a control group (ppm5.4) and three experimental groups (ppm4, ppm2, ppm0)]. RNA sequencing (RNA-seq) data revealed 620 significantly differentially expressed genes (DEGs) in the control and experimental groups. By GO annotation and KEGG enrichment analysis, we found that hypoxia significantly downregulated genes associated with the immune system and inflammation, and actively maintained dissolved oxygen uptake through angiogenesis. In addition, the expression patterns of genes involved in the inhibition of cell growth and proliferation were altered under hypoxic conditions. All those mechanisms may represent a particularly important strategy for energy conservation. This study also laid the foundation for further research on the conditions associated with hypoxia in T. rubripes culture, and was helpful to the selective breeding of T. rubripes for stress tolerance.