TY  - JOUR
A1  - Batram, Christopher
A1  - Jones, Nivola G.
A1  - Janzen, Christian J.
A1  - Markert, Sebastian M.
A1  - Engstler, Markus
T1  - Expression site attenuation mechanistically links antigenic variation and development in Trypanosoma brucei
JF  - eLife
N2  - We have discovered a new mechanism of monoallelic gene expression that links antigenic variation, cell cycle, and development in the model parasite Trypanosoma brucei. African trypanosomes possess hundreds of variant surface glycoprotein (VSG) genes, but only one is expressed from a telomeric expression site (ES) at any given time. We found that the expression of a second VSG alone is sufficient to silence the active VSG gene and directionally attenuate the ES by disruptor of telomeric silencing-1B (DOT1B)-mediated histone methylation. Three conserved expression-site-associated genes (ESAGs) appear to serve as signal for ES attenuation. Their depletion causes G1-phase dormancy and reversible initiation of the slender-to-stumpy differentiation pathway. ES-attenuated slender bloodstream trypanosomes gain full developmental competence for transformation to the tsetse fly stage. This surprising connection between antigenic variation and developmental progression provides an unexpected point of attack against the deadly sleeping sickness.
KW  - antigenic variation
KW  - expression site attenuation
KW  - developmental reprogramming
KW  - cell biology
KW  - genes and chromosomes
KW  - Trypanosoma brucei
KW  - variant surface glycoprotein (VSG)
KW  - monoallelic expression
Y1  - 2014
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-119727
SN  - 2050-084X
VL  - 3
IS  - e02324
ER  - 
TY  - JOUR
A1  - Markert, Sebastian M.
A1  - Skoruppa, Michael
A1  - Yu, Bin
A1  - Mulcahy, Ben
A1  - Zhen, Mai
A1  - Gao, Shangbang
A1  - Sendtner, Michael
A1  - Stigloher, Christian
T1  - Overexpression of an ALS-associated FUS mutation in C. elegans disrupts NMJ morphology and leads to defective neuromuscular transmission
JF  - Biology Open
N2  - The amyotrophic lateral sclerosis (ALS) neurodegenerative disorder has been associated with multiple genetic lesions, including mutations in the gene for fused in sarcoma (FUS), a nuclear-localized RNA/DNA-binding protein. Neuronal expression of the pathological form of FUS proteins in Caenorhabditis elegans results in mislocalization and aggregation of FUS in the cytoplasm, and leads to impairment of motility. However, the mechanisms by which the mutant FUS disrupts neuronal health and function remain unclear. Here we investigated the impact of ALS-associated FUS on motor neuron health using correlative light and electron microscopy, electron tomography, and electrophysiology. We show that ectopic expression of wild-type or ALS-associated human FUS impairs synaptic vesicle docking at neuromuscular junctions. ALS-associated FUS led to the emergence of a population of large, electron-dense, and filament-filled endosomes. Electrophysiological recording revealed reduced transmission from motor neurons to muscles. Together, these results suggest a pathological effect of ALS-causing FUS at synaptic structure and function organization.
KW  - C. elegans
KW  - fused in sarcoma
KW  - amyotrophic lateral sclerosis
KW  - uper-resolution array tomography
KW  - electron tomography
KW  - neuromuscular junction
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-230662
VL  - 9
ER  - 
TY  - JOUR
A1  - Jahn, Martin T.
A1  - Markert, Sebastian M.
A1  - Ryu, Taewoo
A1  - Ravasi, Timothy
A1  - Stigloher, Christian
A1  - Hentschel, Ute
A1  - Moitinho-Silva, Lucas
T1  - Shedding light on cell compartmentation in the candidate phylum Poribacteria by high resolution visualisation and transcriptional profiling
JF  - Scientific Reports
N2  - Assigning functions to uncultivated environmental microorganisms continues to be a challenging endeavour. Here, we present a new microscopy protocol for fluorescence in situ hybridisation-correlative light and electron microscopy (FISH-CLEM) that enabled, to our knowledge for the first time, the identification of single cells within their complex microenvironment at electron microscopy resolution. Members of the candidate phylum Poribacteria, common and uncultivated symbionts of marine sponges, were used towards this goal. Cellular 3D reconstructions revealed bipolar, spherical granules of low electron density, which likely represent carbon reserves. Poribacterial activity profiles were retrieved from prokaryotic enriched sponge metatranscriptomes using simulation-based optimised mapping. We observed high transcriptional activity for proteins related to bacterial microcompartments (BMC) and we resolved their subcellular localisation by combining FISH-CLEM with immunohistochemistry (IHC) on ultra-thin sponge tissue sections. In terms of functional relevance, we propose that the BMC-A region may be involved in 1,2-propanediol degradation. The FISH-IHC-CLEM approach was proven an effective toolkit to combine -omics approaches with functional studies and it should be widely applicable in environmental microbiology.
KW  - high resolution visualisation
KW  - transcriptional profiling
KW  - FISH-CLEM
KW  - cell compartmentation
Y1  - 2016
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-167513
VL  - 6
IS  - 35860
ER  -