Global warming affects marine organisms by increasing water temperature. Starry flounder, Platichthys stellatus, is an economically important species widely distributed throughout the North Pacific Ocean. P. stellatus exhibits relatively poor thermal tolerance, which frequently suffers from mass mortality during summer in an aquaculture system. This study provides transcriptomes for profiling the gene expression responses to heat stress in the liver of P. stellatus, and several target genes involved in functional categories related to heat responses were identified. The experiment was conducted that moderate heat stress was applied by increasing the temperature at a constant rate (increments of 1°C per 12 h) from 16°C to 28°C.
A total of 18,774,222 raw reads in the 16°C group and 16,121,503 raw reads in the 28°C group were obtained from three libraries, and the number of clean reads was 18,254,358 in the 16°C group and 15,677,787 in 28°C group. The genes expressed differentially upregulated and downregulated in P. stellatus under heat stress from 16? to 28? were identified. Of the total DEGs, 1,196 genes were downregulated, and 1,779 genes were upregulated depending on water temperature. Among the total DEGs of 2,975, 1,944 genes were enriched with 30 GO terms (corrected p < 0.05), cellular process (GO:0009987, 303), metabolic process (GO:0008152, 244), and biological regulation (GO:0065007, 128) were highest enriched in biological process. In addition, cellular anatomical entity (GO:0110165, 301) was the highest classified in a cellular component, and catalytic activity (GO:0003824, 184) was the highest enriched in the category of molecular function. In the analysis of 47 KEGG pathways, signal transduction (723) belonging to the category of environmental information processing was classified with the highest number of upregulated DEGs, and the highest number of downregulated DEGs was found in global and overview maps (240) belonging to metabolism. In addition, WASF3, CTSE, UGT, TLR5, EGR2, GLT25D, HERC4, DNAJB1, EGR1, FOS, JUNB, IL13RA1, FKBP4_5, FOSL2, MTHFD2, HSPB1, and Hsp90A were the most differentially expressed genes between the 16°C group and 28°C group.