Dynamic molecular responses of the sea urchin Strongylocentrotus intermedius to pathogen infection: Insights from a serial comparative transcriptome analysis

Abstract

To explore the dynamic molecular responses to pathogen infection in sea urchins, the sea urchin Strongylocentrotus intermedius were infected by a causative pathogen strain of sea urchin black peristomial membrane disease. Specimens were collected at 0, 6, 12, 24, 48, 72, and 96 h post–infection (hpi), and comparative transcriptome analysis were performed. The results showed that 1) a total of 771, 1437, 3477, 8417, 1566, and 2171 differentially expressed genes (DEGs) were identified at 6, 12, 24, 48, 72, and 96 hpi compared with the 0 hpi (as the control), respectively. 2) The number of upregulated DEGs was higher than that of downregulated DEGs at each time point after infection. The largest number of DEGs was obtained at 48 hpi. 3) Among identified DEGs, percent cellular process, binding, and metabolic process related DEGs account for 57.9 %, 49.9 %, and 45.5 %, respectively. Main Rho–GTPase family members (RhoA, Rac1, and Cdc42) exhibited a general upregulated expression trend during the examined infection process, the same as Caspase family members (Casp3, Casp6 and Casp7). 4) Cell cycle and apoptosis pathways are the most affected pathways, the DEG enrichment level of which remained in the top 30 (cell cycle pathways) and top 50 (apoptosis pathways) throughout the whole examined infection process. To sum up, all findings from this study will not only deepen our understanding of the dynamic molecular expression mechanisms of sea urchins in response to pathogen infection, but also provide new clues for elutriating the profound mechanisms of serial gene expression in innate immunity.