Cell Biology Seminars and Progress Reports

A neural stem cell in mitosis DNA

Microcephaly is a rare neurodevelopmental disease that leads to reduced brain size. The disease can have numerous causes such as an infection by the infamous Zika virus and genetic defects. Rohan Chippalkatti and Beat Suter from the ICB (UniBE) collaborated with Boris Egger (Biology, University of Fribourg) to find out what such a genetic factor really does to ensure that the brain develops to its normal size. Their work in the fruit fly Drosophila melanogaster revealed that the gene Mms19 helps the neural stem cells to divide and proliferate rapidly and precisely.  Misregulation of these mechanisms during fly brain development leads to reduced brain growth, but can also cause tumorous overgrowth

Tissue-Specific Transcription Footprinting Using RNA PoI DamID (RAPID) in Caenorhabditis elegans

Differential gene expression across cell types underlies the development and cell physiology in multicellular organisms. C. elegans is a powerful, extensively used model to address these biological questions. A remaining bottleneck relates, however, to the difficulty to obtain comprehensive tissue-specific gene transcription data, since available methods are still challenging to execute and/or require large worm populations. Here, we introduce the RNA Pol DamID (RAPID) approach, in which the Dam methyltransferase is fused to a ubiquitous RNA polymerase subunit in order to create transcriptional footprints via methyl marks on the DNA of transcribed genes. To validate the method, we determined the polymerase footprints in whole animals, sorted embryonic blastomeres and in different tissues from intact young adults by driving Dam fusion expression tissue-specifically. We obtained meaningful transcriptional footprints in line with RNA-seq studies in whole animals or specific tissues. To challenge the sensitivity of RAPID and demonstrate its utility to determine novel tissue-specific transcriptional profiles, we determined the transcriptional footprints of the pair of XXX neuroendocrine cells, representing 0.2% of the somatic cell content of the animals. We identified 2362 candidate genes with putatively active transcription in XXX cells, among which the few known markers for these cells. Using transcriptional reporters for a subset of new hits, we confirmed that the majority of them were expressed in XXX and identified novel XXX-specific markers. Taken together, our work establishes RAPID as a valid method for the determination of polymerase footprints in specific tissues of C. elegans without the need for cell sorting or RNA tagging.

New study from the Ochsenreiter lab on different methods to analyse mitochondrial biogenesis aspects in Trypanosoma brucei.

Trypanosoma brucei is a single celled eukaryotic parasite and the causative agent of human African trypanosomiasis and nagana in cattle. Aside from its medical relevance, T. brucei has also been key to the discovery of several general biological principles including GPI-anchoring, RNA-editing and trans-splicing. The parasite contains a single mitochondrion with a singular genome. Recent studies have identified several molecular components of the mitochondrial genome segregation machinery (tripartite attachment complex, TAC), which connects the basal body of the flagellum to the mitochondrial DNA of T. brucei. The TAC component in closest proximity to the mitochondrial DNA is TAC102. Here we apply and compare three different approaches (proximity labelling, immunoprecipitation and yeast two-hybrid) to identify novel interactors of TAC102 and subsequently verify their localisation. Furthermore, we establish the direct interaction of TAC102 and p166 in the unilateral filaments of the TAC

Wir haben keine Angst vor tausend Experimenten

Der Zellbiologe Olivier Pertz hat in den vergangenen vier Jahren in Bern ein sehr erfolgreiches, interdisziplinäres Team aufgebaut, das Signalnetzwerke in Zellpopulationen untersucht. Im Interview spricht er über die Schwarmintelligenz von Zellen, «gepimpte» Mikroskope und warum sein Team keine Angst vor Big Data hat.

The pursuit of a professorship requires hard work, courage and patience

Carmen Faso is one of the first recipients of an SNSF PRIMA grant which target outstanding female researchers who have professorial potential. The cell biologist recently started her research project on intestinal parasites at the Institute of Cell Biology of the University of Bern.

Targeting Plasmodium Plasmepsin V: Hitting Two Birds with One Stone

Researchers from the ICB and the Swiss Tropical and Public Health Institute in Basel highlight the finding of a potential drug target against Malaria. A recent report by Jennison et al. from the Walter and Eliza Hall Institute in Melbourne, Australia, reveals an important role for plasmepsin V in the development of malaria transmission stages. The authors showed that plasmepsin V activity is critical for protein export in these stages and that specific inhibitors block parasite transmission to mosquitoes.

Breakthrough in malaria research

An international scientific consortium led by the cell biologists Volker Heussler from the University of Bern and Oliver Billker from the Umeå University in Sweden has for the first time systematically investigated the genome of the malaria parasite Plasmodium throughout its life cycle in a large-scale experiment. The researchers were able to identify hundreds of targets that are urgently needed in drug and vaccine development to eradicate the disease.

Roles of Phosphoinositides and Their binding Proteins in Parasitic Protozoa

Phosphoinositides (or phosphatidylinositol phosphates, PIPs) are low-abundance embrane
phospholipids that act, in conjunction with their binding partners, as important constitutive signals defining biochemical organelle identity as well as membrane trafficking and signal transduction at eukaryotic cellular membranes. In this review, we present roles for PIP residues and PIPbinding proteins in endocytosis and autophagy in protist parasites such as Trypanosoma brucei, Toxoplasma gondii, Plasmodium falciparum, Entamoeba histolytica,andGiardia lamblia.Molec-ular parasitologists with an interest in comparative cell and molecular biology of membrane traf-ficking in protist lineages beyond the phylum Apicomplexa, along with cell and molecular biologists generally interested in the diversification of membrane trafficking in eukaryotes, will hopefully find this review to be a useful resource.