Endoreplication Controls Cell Fate Maintenance

Cell-fate specification is typically thought to precede and determine cell-cycle regulation during differentiation. Here we show that endoreplication, also known as endoreduplication, a specialized cell-cycle variant often associated with cell differentiation but also frequently occurring in malignant cells, plays a role in maintaining cell fate. For our study we have used Arabidopsis trichomes as a model system and have manipulated endoreplication levels via mutants of cell-cycle regulators and overexpression of cell-cycle inhibitors under a trichome-specific promoter. Strikingly, a reduction of endoreplication resulted in reduced trichome numbers and caused trichomes to lose their identity. Live observations of young Arabidopsis leaves revealed that dedifferentiating trichomes re-entered mitosis and were re-integrated into the epidermal pavement-cell layer, acquiring the typical characteristics of the surrounding epidermal cells. Conversely, when we promoted endoreplication in glabrous patterning mutants, trichome fate could be restored, demonstrating that endoreplication is an important determinant of cell identity. Our data lead to a new model of cell-fate control and tissue integrity during development by revealing a cell-fate quality control system at the tissue level

Pharmasquare (Pharma²)

The project Pharmasquare (Pharma2) is based on the regular course 'Pharmaceutical Chemistry: Drug Effects on the Molecular Level' alternately presented in Zürich and Basel using the videoconferencing system Telepoly. The course is part of an open learning environment, which is currently complemented by distant learning facilities including a virtual learning environment. Pharma2 receives financial support from the Swiss Virtual Campus, the ETHZ, and matching funds by the Universities of Basel and Neuchâtel. In its final form, the virtual learning environment will offer web-based training modules, a virtual laboratory, the adaptive self-assessment system PharmAskYou, scripts of the Telepoly lectures including learning objectives, a glossary in pharmaceutical sciences, a news-platform, a discussion forum and the 'Question of the Week'