Sydney Rock oysters (SRO) reflect the Australian way of life. Their limited distribution along the coast of NSW makes them precious from both an ecological and economic point of view. In recent years, especially since the 1990s, a few diseases such as winter mortality (WM) and Queensland Unknown (QX) have impacted SRO farming greatly. Selective breeding has provided a temporary relief by reducing the mortality rate of the oysters. The selection, however, is not backed by the knowledge of genes helping the cause. In this attempt to unravel the phenomenon underlying the mechanisms of selection we have performed a proteomic analysis of WM and QX disease resistant selected oysters.
We approached the WM study using traditional 2DE in conjunction with LC-MS/MS. The results showed cytoskeletal breakdown as a result of disease stress, and we also identified novel proteins such as proteasome subunit alpha type-6 and calcium-dependent protein kinase 31. These proteins have not been reported previously in the context of disease resistance in oysters. Result from this study added to the knowledge of stress response pathways of SRO.
For the QX study, oysters sampled at different time points were used to generate proteome information and to get an idea about disease progression as well. The shotgun proteomics study identified at very high stringency ~150 reproducibly identified proteins. We have observed a notable increase in enzymes associated with energy consumption (ATP synthase), proteolysis (proteasome) in the case of non-selected oysters, which supports the previous observation regarding cytoskeletal breakdown pathway. A few proteins identified in this study, such as HMGB1, are known to be involved in immune response and inflammation, and represent promising candidates for further study.
The general idea from this study is to identify the underlying mechanism involved in selective breeding.