Molecular analysis of stress in Sydney Rock oysters (Saccostrea glomerata)

Oysters are an ecologically and economically important marine species that have contributed over AU$107 million (edible oysters only) to the Australian economy in 2011-2012. However, as other marine organisms, cultivated and wild oysters are challenged by a variety of environmental stressors that are quite likely to be exacerbated by anthropogenic and climate influences (e.g. CO2, extreme weather events). These stressors in general have the potential to weaken oysters, lowering their ability to cope with additional stress, such as disease or pollution. In an aquaculture environment, this could impact on the productivity and profitability of the industry. To maintain and potentially improve the health and resilience of oysters, knowledge needs to be gained regarding not only the physiological but also molecular responses to stress. This study aims to determine which genes are actively expressed in stressed and non-stressed Sydney Rock oysters and to highlight genes potentially involved in the molecular stress response of these oysters. Adult Sydney Rock oysters (economic value of nearly AU$ 30 million in 2012-13) were exposed to a range of environmental stressors (CO2, temperature, salinity, copper and polycyclic aromatic hydrocarbons [PAH]) in a laboratory environment and pools of six tissues (haemolymph, gill, mantle, adductor muscle, digestive system and gonad) of all experimental animals examined with RNA-seq. Furthermore, 48 individuals exposed to CO2 and temperature, salinity and temperature or PAH were closely examined for differential gene expression in response to the stressors. Genes actively expressed in stressed and non-stressed Sydney Rock oysters are involved in a variety of biological processes, including immune responses and known responses to stress