| Summary: | The foundations of this thesis were based on synthesising a cDNA library from a mixture of S. parasitica zoospores, cysts and germinating cysts. From this library, 978 ESTs were generated and bioinformatics analysis was performed on these. A range of interesting candidates were identified with putative functions including: sterol metabolites, which are always found in oomyctes; fungal type I cellulose binding domains that may aid in the attachment of S. parasitica to the host surface; and disintegrin, which in general have anti-coagulation properties. A putative kazal-like serine protease inhibitor, termed Kaz1, was identified from the cDNA library. It is anticipated that it may play a role in the virulence of S. parasitica by blocking the actions of proteolytic enzymes released by the threatened fish, thus acting in a defence-counter-defence strategy. A putative host targeting system has been identified in oomycetes, which is dependent on the RxLR-dEER motif. This thesis describes the over-expression and purification of a FLAG-tagged fusion protein of RxLR2, an RxLR protein from S. parasitica. Two putative SNARE proteins, termed Syntax1 and Synap1 were also identified in the pre-infective cDNA library. These candidate proteins may be involved in the development of S. parasitica. The bioinformatics characterisation of these proteins is described, and their expression throughout the lifecycle of S. parasitica analysed. This thesis provides the first insight into what genes and proteins are involved in the development and pathogenicity of S. parasitica, and proposes methods that may be used by the pathogen for successful infection of its host.
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