2011/718 Molecular analysis of the effect of stressors on oysters

By Nicole Ertl

During their life-time, cultivated and wild oysters are exposed to a variety of environmental stressors, including salinity and temperature fluctuations, pollution and pathogens in their natural habitat. These stressors are quite likely to act synergistically and can be exacerbated by anthropogenic and climate influences (e.g. CO2, extreme weather events). They also have the potential to weaken the oysters, causing them to succumb to disease or predation pressures. In an aquaculture environment, this could impact on the productivity and profitability of the industry.

For this study, wild Sydney Rock Oysters (Saccostrea glomerata) were challenged with sub-optimal levels of a) CO2 and temperature, b) copper, c) salinity and temperature and d) polycyclic aromatic hydrocarbons (PAHs) to mimic oil contamination. Collected tissues (haemolymph, gill, mantle, adductor muscle, digestive system and gonad) of all experimental animals were used to generate a S. glomerata transcriptome. Close examination of the transcriptome revealed a wide range of transcripts believed to be involved in innate immunity, with some of them appearing to be largely conserved between mammals and invertebrates (e.g. oysters). Furthermore, a few selected transcripts were observed to be expressed in specific tissues (e.g. only in the haemolymph).

This project was the first large scale transcriptomics study carried out in S. glomerata, showing that these oysters have the potential to protect themselves against a range of pathogens and stressors. The molecular response to a variety of stressors appears to be complex, with some transcripts appearing to respond to more than one environmental stressor. In addition, specific transcripts and their expression pattern displayed a unique profile across stressors. Overall, this study adds to the current knowledge on immunity and stress response in molluscs in general and in the commercially important S. glomerata in particular.