Genetic Mainpulation of Silica Morphogenesis in the Diatom Thalassiosira pseudonana

• Applicant: Professor Dr. André Scheffel
• Subject Area: Plant Genetics and Genomics
• Term: from 2008 to 2011
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 79131977

The intricate species specific, siliceous cell walls of diatoms (microalgae) are one of the most fascinating examples for the widespread biological phenomenon of controlled mineral formation by organisms. The silaffins, a unique family of phosphoproteins entrapped in the biosilica cell walls, are suspected to play an important role in diatom cell wall formation. However, the in vivo role of the silaffins has not been investigated, yet. To clarify the role of the silaffins in diatom cell wall formation in vivo, is the primary goal of this project. Therefore the project proposed here, attempts for the first time ever, to down-regulate silaffin expression in the model diatom Thalassiosira pseudonana through genetic engineering. Downregulation of silaffin expression will be attempted in two independent projects by post-transcriptional silencing using silaffin-specific ribozymes and silaffin antisense RNAs, and by targeting the silaffin genes for replacement via homologous recombination. Methods for post-transcriptional silencing and for homologous gene targeting in diatoms will be developed in this project as they are not established, yet. Resulting mutants will be analyzed for silaffin down-regulation and for structural changes in the cell wall that are expected to occur in case of substantial silaffin down-regulation. This project will make a significant contribution to the quest for solving the enigma of biological cell wall morphogenesis in diatoms and will expand the molecular tool kit for making diatoms amenable for functional genetic analysis.

• DFG Programme: Research Fellowships
• International Connection: USA
• Host: Professor Dr. Nils Kröger