Seminar Lucia Poggi e Matthias Carl

Venue: Edificio Povo 2, via Sommarive nr. 9, Povo (Tn) - Room B105
 at 2:00 p.m.

• Lucia Poggi -  Department of Developmental Biology & Physiology,Universität Heidelberg, Heidelberg, Germany

Understanding Cell Division and Lineage-Progression of Fate­‐Restricted Retinal Progenitor Cells In Vivo

The molecular mechanisms of neuronal diversification and lineage progression of neural progenitor cells in vivo remain rather unknown. To understand this we apply time-­lapse imaging in the retinal neuroepithelium of the optically transparent Zebrafish embryo in combination with genetics and cell biology. This allows us to concurrently trace the history of a progenitor cell from its emergence to its extinction, monitor temporal patterns of gene expression and elucidate the underlying molecular regulatory processes. We collected evidence that particular subtypes of molecularly identified progenitor cells with restricted fate choices display invariable lineage patterns consisting of asymmetric cell divisions and lineage-­restricted gene expression. This suggests that cell-­autonomous mechanisms might be at the heart of these lineage-­ patterns. In addition, extrinsic negative feedback signals and cell-­cell interactions,  such as the ones mediated by Notch signaling can modify modes of division and neural fate decisions in these progenitors. Thus, both cell-­autonomous mechanisms (e.g. transcription factors and chromatin regulators) and highly reproducible cell­‐cell interactions might contribute to such invariant division patterns in vivo. We now collected evidence suggesting that the F­‐actin binding protein Anillin might be an important bridging factor at the intersection of intrinsic cell fate determinants and cell polarity cues, essential for the asymmetry of cell division and lineage progression. These insights lay the groundwork whereby we can advance our integrated molecular understanding of how intrinsic and extrinsic signals might intersect during cell division to balance diversity and order within specific neural lineages.

Venue: Edificio Povo 2, via Sommarive nr. 9, Povo (Tn) - Room B105
 at 2:45 p.m.

• Matthias Carl -  Department of Cell and Molecular Biology, University of Heidelberg, Mannheim, Germany

Dissecting the genetics and function of left-right brain asymmetries

Neuroanatomical and functional differences between the left and right brain hemisphere are characteristics of every vertebrate brain. If and how these are linked and influence our daily life and behavior is however a long-standing question in neuroscience. Recent progress in establishing the conserved habenular neural circuit as a model system now nourishes hopes to elucidate this enigma. Habenular function regulates various behaviors and aberrations have been implicated in pathophysiological syndromes. Like in many vertebrates, this neurotransmitter system in the zebrafish forebrain exhibits pronounced left-right differences in the size of neuronal populations and axonal connectivity patterns. On the molecular level, we have identified the Wnt/beta-catenin signaling pathway as a major regulator of the establishment of this asymmetry. On the network level, combinations of in vivo time-lapse analysis and computational depth color coding let us discover a mechanism by which habenular efferent axons find their way through the brain to innervate their targets in the midbrain. Our investigations further established a link between anatomical and functional habenular asymmetry, which now gives us a headstart to generate a functional connectome for the relay of sensory information in the asymmetric brain.