@article{BrehmHemerKonradetal.2014, author = {Brehm, Klaus and Hemer, Sarah and Konrad, Christian and Spiliotis, Markus and Koziol, Uriel and Schaack, Dominik and F{\"o}rster, Sabine and Gelmedin, Verena and Stadelmann, Britta and Dandekar, Thomas and Hemphill, Andrew}, title = {Host insulin stimulates Echinococcus multilocularis insulin signalling pathways and larval development}, doi = {10.1186/1741-7007-12-5}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-110357}, year = {2014}, abstract = {Background The metacestode of the tapeworm Echinococcus multilocularis is the causative agent of alveolar echinococcosis, a lethal zoonosis. Infections are initiated through establishment of parasite larvae within the intermediate host's liver, where high concentrations of insulin are present, followed by tumour-like growth of the metacestode in host organs. The molecular mechanisms determining the organ tropism of E. multilocularis or the influences of host hormones on parasite proliferation are poorly understood. Results Using in vitro cultivation systems for parasite larvae we show that physiological concentrations (10 nM) of human insulin significantly stimulate the formation of metacestode larvae from parasite stem cells and promote asexual growth of the metacestode. Addition of human insulin to parasite larvae led to increased glucose uptake and enhanced phosphorylation of Echinococcus insulin signalling components, including an insulin receptor-like kinase, EmIR1, for which we demonstrate predominant expression in the parasite's glycogen storage cells. We also characterized a second insulin receptor family member, EmIR2, and demonstrated interaction of its ligand binding domain with human insulin in the yeast two-hybrid system. Addition of an insulin receptor inhibitor resulted in metacestode killing, prevented metacestode development from parasite stem cells, and impaired the activation of insulin signalling pathways through host insulin. Conclusions Our data indicate that host insulin acts as a stimulant for parasite development within the host liver and that E. multilocularis senses the host hormone through an evolutionarily conserved insulin signalling pathway. Hormonal host-parasite cross-communication, facilitated by the relatively close phylogenetic relationship between E. multilocularis and its mammalian hosts, thus appears to be important in the pathology of alveolar echinococcosis. This contributes to a closer understanding of organ tropism and parasite persistence in larval cestode infections. Furthermore, our data show that Echinococcus insulin signalling pathways are promising targets for the development of novel drugs.}, language = {en} } @article{RufFraunholzOechsneretal.2017, author = {Ruf, Franziska and Fraunholz, Martin and {\"O}chsner, Konrad and Kaderschabeck, Johann and Wegener, Christian}, title = {WEclMon - A simple and robust camera-based system to monitor Drosophila eclosion under optogenetic manipulation and natural conditions}, series = {PLoS ONE}, volume = {12}, journal = {PLoS ONE}, number = {6}, doi = {10.1371/journal.pone.0180238}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-170755}, pages = {e0180238}, year = {2017}, abstract = {Eclosion in flies and other insects is a circadian-gated behaviour under control of a central and a peripheral clock. It is not influenced by the motivational state of an animal, and thus presents an ideal paradigm to study the relation and signalling pathways between central and peripheral clocks, and downstream peptidergic regulatory systems. Little is known, however, about eclosion rhythmicity under natural conditions, and research into this direction is hampered by the physically closed design of current eclosion monitoring systems. We describe a novel open eclosion monitoring system (WEclMon) that allows the puparia to come into direct contact with light, temperature and humidity. We demonstrate that the system can be used both in the laboratory and outdoors, and shows a performance similar to commercial closed funnel-type monitors. Data analysis is semi-automated based on a macro toolset for the open imaging software Fiji. Due to its open design, the WEclMon is also well suited for optogenetic experiments. A small screen to identify putative neuroendocrine signals mediating time from the central clock to initiate eclosion showed that optogenetic activation of ETH-, EH and myosuppressin neurons can induce precocious eclosion. Genetic ablation of myosuppressin-expressing neurons did, however, not affect eclosion rhythmicity.}, language = {en} } @article{MuellerCosentinoFoerstneretal.2018, author = {M{\"u}ller, Laura S. M. and Cosentino, Ra{\´u}l O. and F{\"o}rstner, Konrad U. and Guizetti, Julien and Wedel, Carolin and Kaplan, Noam and Janzen, Christian J. and Arampatzi, Panagiota and Vogel, J{\"o}rg and Steinbiss, Sascha and Otto, Thomas D. and Saliba, Antoine-Emmanuel and Sebra, Robert P. and Siegel, T. Nicolai}, title = {Genome organization and DNA accessibility control antigenic variation in trypanosomes}, series = {Nature}, volume = {563}, journal = {Nature}, doi = {10.1038/s41586-018-0619-8}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-224265}, pages = {121-125}, year = {2018}, abstract = {Many evolutionarily distant pathogenic organisms have evolved similar survival strategies to evade the immune responses of their hosts. These include antigenic variation, through which an infecting organism prevents clearance by periodically altering the identity of proteins that are visible to the immune system of the host1. Antigenic variation requires large reservoirs of immunologically diverse antigen genes, which are often generated through homologous recombination, as well as mechanisms to ensure the expression of one or very few antigens at any given time. Both homologous recombination and gene expression are affected by three-dimensional genome architecture and local DNA accessibility2,3. Factors that link three-dimensional genome architecture, local chromatin conformation and antigenic variation have, to our knowledge, not yet been identified in any organism. One of the major obstacles to studying the role of genome architecture in antigenic variation has been the highly repetitive nature and heterozygosity of antigen-gene arrays, which has precluded complete genome assembly in many pathogens. Here we report the de novo haplotype-specific assembly and scaffolding of the long antigen-gene arrays of the model protozoan parasite Trypanosoma brucei, using long-read sequencing technology and conserved features of chromosome folding4. Genome-wide chromosome conformation capture (Hi-C) reveals a distinct partitioning of the genome, with antigen-encoding subtelomeric regions that are folded into distinct, highly compact compartments. In addition, we performed a range of analyses—Hi-C, fluorescence in situ hybridization, assays for transposase-accessible chromatin using sequencing and single-cell RNA sequencing—that showed that deletion of the histone variants H3.V and H4.V increases antigen-gene clustering, DNA accessibility across sites of antigen expression and switching of the expressed antigen isoform, via homologous recombination. Our analyses identify histone variants as a molecular link between global genome architecture, local chromatin conformation and antigenic variation.}, language = {en} }