Molecular Processes and Hub Genes of Acropora palmata in Response to Thermal Stress and Bleaching

Among many environmental factors, high temperature is the main factor that causes coral bleaching. Thus, analyses of the bleaching mechanism and important genes involved in coral responses to thermal stress and bleaching are important. This study explored the gene expression profiling data (GSE16151) from the Gene Expression Omnibus database by using bioinformatics analysis to study the molecular processes and hub genes involved in the thermal stress and bleaching responses of the coral Acropora palmata. The results suggest that thermal stress down-regulated the snoRNP genes, which led to a reduction of some ribosomal proteins, and then decreased biosynthesis, resulting in disruption of a series of biological processes such as the glyoxylate cycle and vitamin metabolic processes. Moreover, the coral cytoskeleton showed breakdown because the CCT7 gene was down-regulated and because of insufficient adenosine triphosphate production caused by the thermal stress. All these responses will destroy the P53 pathway and initiate apoptosis and ultimately necrosis. In addition, 107 differentially expressed genes were detected between the normal and bleached corals, indicating that snoRNPs, CCT7, RPL37, and RPS27A may be the hub genes responsible for thermal stress and bleaching responses. These genes can be used as new biomarkers to help solve the problem of coral bleaching.