Gene Expression as a Molecular Component of the Physiological Response to Mechanical Shell Damage in the Pacific Oyster Magallana gigas

Shell damage is common in bivalves and initiates repair processes that may affect the physiological state of the organism. We examined temporal changes in the expression of genes related to energy metabolism, antioxidant defense, and innate immunity in the mantle and gills of the Pacific oyster Magallana gigas during 14 days following experimental shell damage. In the mantle, PDK1 expression increased on day 1, while on day 7 both PDK1 and IDH expression decreased. The latter period was also characterized by decreased expression of the antioxidant defense-related genes Mn-SOD and GPx and the immune-related gene TNF-2. In the gills, fewer changes were observed: IDH and IL-17-3 expression decreased on day 1, whereas Toll-1 expression decreased on day 14. No significant differences were detected for the remaining analyzed genes. Thus, significant gene expression differences between shell-damaged and control oysters were detected at different sampling times and showed distinct patterns in the mantle and gills. The mantle showed an early change in the expression of an energy metabolism-related gene, followed by concurrent changes in the expression of genes associated with energy metabolism, antioxidant defense, and immune regulation on day 7. By day 14, no significant differences in the expression of the analyzed mantle genes were detected between shell-damaged and control oysters. The more limited and temporally distinct changes observed in the gills indicate that the gene expression response to shell damage differed between the mantle and gills.