Comparative Transcriptome Analysis of Heart Tissue in Response to Hypoxia in Silver Sillago (Sillago sihama)

Sillago sihama,commonly known as silver sillago,is considered as an economically important fish species in China.It is sensitive to hypoxia stress in the larval stage,and the mechanism has not been understood thoroughly.In this study,we investigated the transcriptome change in heart tissues under hypoxia stress.The fish were divided into four groups,including 1 h of hypoxia(hypoxia1h,dissolved oxygen(DO)=1.5±0.1 mg L^(−1)),4h of hypoxia(hypoxia4h,DO=1.5±0.1 mg L^(−1)),4h of reoxygen(reoxygen4h,DO=8.0±0.2 mg L^(−1))after 4h of hypoxia(DO=1.5 mg L^(−1))and normoxia or control(DO=8.0±0.2 mg L^(−1))groups.The results showed that a total of 3068 genes were identified as differentially expressed genes(DEGs)based on the criteria∣log2(Fold change)∣>1.0 and adjusted P-value<0.05.A total of 7761141 and 1151 DEGs were obtained from hypoxia1h,hypoxia4h and reoxygen4h groups,respectively.The enrichment pathway analysis showed that the DEGs were significantly enriched in ribosome biogenesis in eukaryotes,retinol metabolism,DNA replication and the oxidative phosphorylation(OXPHOS)pathways.Thirteen DEGs from the RNA-seq results were validated by quantitative real-time polymerase chain reaction(qRT-PCR).These candidate genes are considered as important regulatory factors involved in the hypoxia stress response in S.sihama.