p26 Knockdown Modifies the Diapause Proteome of Artemia franciscana

Abstract

The brine shrimp, Artemia franciscana, produces diapausing embryos (cysts), in which biological processes are arrested. Cysts are an excellent model for studying the regulation of diapause because they remain in this state for prolonged periods showing remarkable resistant to harsh environmental conditions and they terminate diapause in response to specific stimuli. p26 is the most abundant diapause protein in the cyst proteome, playing a critical role in embryo development, diapause maintenance, and cyst stress tolerance, the latter presumably by preventing irreversible protein denaturation during stress. p26 is therefore likely to influence many proteins in the cyst diapause proteome. However, the identity of p26 substrates remained largely unknown as did the effect of p26 on protein synthesis. This study represents the first global characterization of the A. franciscana diapause proteome, identifies putative p26 substrates and shows that p26 regulates the synthesis of specific proteins. Advantage was taken of modern proteomic techniques, including 2D-LC MS/MS to analyze and quantify the proteome of the cyst, and RNAi was used to evaluate the affects of knocking down p26 on the diapause proteome. 3212 proteins were detected by MS/MS. Those proteins that varied significantly upon p26 knockdown either have the potential to be p26 substrates or possibly have their synthesis affected by p26.The functional categorization of the proteins was considered using the PANTHER classification system yielding catalysts, binding proteins, structural proteins, transporters, translation factors, receptors, antioxidants, signal transducers, and a channel regulator. This proteomics approach has added valuable information to the global picture of the diapause proteome, making a contribution to understanding p26 influence on diapause and the molecular mechanisms of diapause in A. franciscana.