FG 504: Molecular mechanisms of gene silencing and positional effects in green algae

Albeit being a popular model organism for several biological questions Chlamydomonas transgenics still face some challenges for a full exploitation of its potential both in basic science and biotechnology. One parameter under investigation in this study is the positional effect of random transgene integration into the nuclear genome. A molecular marker system has been created that can be used to monitor activity of phage recombinases in the cell?s nucleus. Information about the influence of flanking genomic regions on transgene expression will be generated from this approach. A second issue addressed in this proposal deals with the recognition and destruction of transgene derived RNA by endogenous defense mechanisms of PTGS. DNA-tagged mutants have been isolated upon insertional mutagenesis that possibly are affected in single components of the PTGS system. In the next step the targeted genes will be identified and characterized by complementation and heterologous expression assays. Combination of molecular genetics and biochemistry with the power of mass-spectrometric protein analysis are going to refine the current picture of PTGS in C. reinhardtii.