Refine
Has Fulltext
- yes (187)
Is part of the Bibliography
- yes (187)
Year of publication
- 2021 (187) (remove)
Document Type
- Journal article (147)
- Doctoral Thesis (37)
- Preprint (2)
- Working Paper (1)
Keywords
- climate change (5)
- Apis mellifera (4)
- Trypanosoma brucei (4)
- biodiversity (4)
- insects (4)
- Neisseria gonorrhoeae (3)
- SARS-CoV-2 (3)
- Staphylococcus aureus (3)
- cancer (3)
- deadwood (3)
- distribution (3)
- evolution (3)
- genome (3)
- meiosis (3)
- metabolism (3)
- neuropeptides (3)
- super-resolution microscopy (3)
- Bordetella pertussis (2)
- COVID-19 (2)
- CSF (2)
- Cataglyphis (2)
- Einzelmolekülspektroskopie (2)
- Fluoreszenzmikroskopie (2)
- Fluoreszenzspektroskopie (2)
- Formicidae (2)
- Genregulation (2)
- Kinetoplastida (2)
- Klimawandel (2)
- LC/MS (2)
- MYCN (2)
- Melanom (2)
- Parkinson's disease (2)
- Photoinduzierter Elektronentransfer (2)
- Proteinsynthese (2)
- abscisic acid (ABA) (2)
- active zone (2)
- adaptation (2)
- antennal lobe (2)
- apoptosis (2)
- behavior (2)
- beta diversity (2)
- biological techniques (2)
- biomarker (2)
- caloric restriction (2)
- central complex (2)
- cerebrospinal fluid (2)
- circadian clock (2)
- cosmology (2)
- dSTORM (2)
- ecology (2)
- endocytosis (2)
- flooding (2)
- fluorescence spectroscopy (2)
- forensic neuropathology (2)
- forensic neurotraumatology (2)
- forest management (2)
- functional diversity (2)
- genomics (2)
- global change (2)
- habitat (2)
- honeybee (2)
- host-pathogen interaction (2)
- imaging (2)
- infection (2)
- isothermal titration calorimetry (2)
- land use (2)
- loop quantum gravity (2)
- mass spectrometry (2)
- methionine restriction (2)
- mitochondria (2)
- nature conservation (2)
- neuroanatomy (2)
- neuromodulation (2)
- nutrients (2)
- nutrition (2)
- p53 (2)
- pH (2)
- photoinduced electron transfer (2)
- plasticity (2)
- proboscis extension response (2)
- proteins (2)
- sturgeon (2)
- time series (2)
- transcriptomics (2)
- trypanosoma (2)
- tsetse fly (2)
- 3D reconstruction (1)
- A2a-R receptor (1)
- ALPH (1)
- ALPH1 (1)
- ATP-DnaA complex (1)
- Abbe-Limit (1)
- African agriculture (1)
- African trypanosome (1)
- African trypanosomes (1)
- Agrarumweltmaßnahmen (1)
- Agro-ecology (1)
- Antagonismus (1)
- Antioxidantien (1)
- ApaH (1)
- ApaH like phosphatase (1)
- Artenvielfalt (1)
- Arthropod (1)
- Aspergillus (1)
- Aspergillus fumigatus (1)
- Aureobasidium (1)
- Aurora-A (1)
- B-cell (1)
- BM (1)
- Basal Ganglia (1)
- Basalganglien (1)
- BayPass (1)
- Biene <Gattung> (1)
- Bienen (1)
- Biodiversität (1)
- Bombus terrestris (1)
- Brain-derived neurotrophic factor (1)
- Bruchpilot (1)
- CA2+ channels (1)
- CA3 pyrimidal cells (1)
- CCR7 (1)
- CD28 (1)
- CETCH cycle (1)
- CO2-sequestration (1)
- COI (1)
- CRC (1)
- CRISPR-Cas9 (1)
- CXCR4 (1)
- Cadherin-13 (CDH13) (1)
- Caenorhabditis elegans (1)
- Caenorhabditis elegans (C. elegans) (1)
- Calciumkanal (1)
- Carabidae (1)
- Cardiomyocyte (1)
- Cdu1 (1)
- Chimpanzee (1)
- ChlaDUB1 (1)
- Chlamydia (1)
- Chlamydia trachomatis (1)
- Chromatin (1)
- Chronobiologie (1)
- Chrysomelidae (1)
- Click-Chemie (1)
- Common Agricultural Policy (1)
- Comoé National Park (1)
- Cortico-striatal projection neurons (1)
- Cryptic species (1)
- Curculionidae (1)
- Cystein (1)
- DNA damage (1)
- DNA nanotechnology (1)
- DNA repair (1)
- DNA replication initiation (1)
- DNA-PK (1)
- DOT1 (1)
- DOT1B (1)
- DUB inhibitor (1)
- DeepSqueak (1)
- Dopaminergic PAM cluster neurons (1)
- Drosophila (1)
- ERG (1)
- ERK-Kaskade (1)
- ERK-cascade (1)
- Ecosystem services (1)
- Einzelmolekül-Lokalisationsmikroskopie (1)
- Elektronenmikroskopie (1)
- Emotional behavior (1)
- Europe (1)
- European beech (1)
- Evolution (1)
- Expansionsmikroskopie (1)
- FBXW7 (1)
- FIB-SEM (1)
- Fluorescence spectroscopy (1)
- Fluoreszenzkorrelationsspektroskopie (1)
- Fluoreszenzsonden (1)
- Fungal traits (1)
- GABA-A receptor (1)
- GDNF5 (1)
- GPI-anchor (1)
- GWAS (1)
- Gallium-68 Pentixafor (1)
- Genexpression (1)
- Genotype-phenotype relationship (1)
- Glutamatrezeptor (1)
- Glutathion (1)
- Golgi (1)
- HHV-6 (1)
- HIV (1)
- Halictidae (1)
- HeLa cells (1)
- Heart development (1)
- Hepatitis B Virus (1)
- Herpesvirus (1)
- Herzhypertrophie (1)
- Herzmuskelzelle (1)
- Heterogenität (1)
- High-End-Mikroskopie (1)
- Hill numbers (1)
- Hippo pathway (1)
- Histon-Methyltransferase (1)
- Histone gamma H2AX (1)
- Hitzeschock-Proteine (1)
- Hochaufgelöste Fluoreszenzmikroskopie (1)
- Hsp90 (1)
- Hurwitz-Theorem (1)
- IL2 branching (1)
- In vitro (1)
- In-silico Modell (1)
- IncuCyte\(^®\)S3 (1)
- Insect pests (1)
- Insektenstaaten (1)
- Interaktion (1)
- Ionotrope Glutamatrezeptoren (1)
- Ips typographus (1)
- JUN (1)
- Ki67 (1)
- Kinetoplastea (1)
- Klimaerwärmung (1)
- Klimaneutralität (1)
- Klimapflanzen (1)
- Klimaänderung (1)
- Kosmologie (1)
- Krebsforschung (1)
- L929 (1)
- Landnutzung (1)
- Landscape ecology (1)
- Lebensraum (1)
- Legume crops (1)
- Leishmania (1)
- Lepidoptera (1)
- Lichtheimia (1)
- Life expectancy (1)
- Ligandenbindedomäne (1)
- LysR-type (1)
- MALDI imaging (1)
- MAX (1)
- MHC I (1)
- MHC II (1)
- MSCI (1)
- MYC (1)
- Mauerbiene (1)
- Mbt (1)
- Medium spiny neurons (1)
- Membrane receptor (1)
- Membranrezeptor (1)
- Modul (1)
- Module search (1)
- Modulsuche (1)
- Motilität (1)
- Motor learning (1)
- Motorisches Lernen (1)
- Multiples Myelom (1)
- Mutualismus (1)
- Myatrophische Lateralsklerose (1)
- Myb-MuvB complex (1)
- NRF2 (1)
- Negative geotaxis (1)
- Neisseria (1)
- Neuroanatomie (1)
- Neuroblastom (1)
- Neuroethologie (1)
- Neuropeptide (1)
- Non-coding RNA (1)
- Nuclear export control (1)
- Nuclear periphery granules (1)
- Olea (1)
- Oxidativer Stress (1)
- PAK4 (1)
- PALM (1)
- PER (1)
- Pacific Ocean (1)
- Pangenom (1)
- Parasit (1)
- Parasitoid (1)
- Parc National de la Comoé (1)
- Parkinson Krankheit (1)
- Persistence (1)
- Pflanzen (1)
- Phenotypic switch (1)
- Phänologie (1)
- Pilze (1)
- PknB (1)
- Plant-insect interactions (1)
- Plasmozytom (1)
- Plastizität (1)
- Pollen (1)
- Pollination (1)
- Promotor <Genetik> (1)
- Proteinmarkierungen (1)
- Pseudotsuga menziesii (1)
- Quantenschleifen-Gravitation (1)
- Qubits (1)
- R-loop (1)
- RET6 (1)
- RIM-binding protein (1)
- RNA (1)
- RNA Motivsuche (1)
- RNA granules (1)
- RNA motiv serach (1)
- RNA polymerase II (1)
- RNAseq (1)
- RRID: AB_2315425 (1)
- RRID: AB_2337244 (1)
- Rab (1)
- Radiation sensitivity (1)
- Ribonuclease H2 (1)
- Rnsstoffwechsel (1)
- S-type anion channel (1)
- SCC (1)
- SIM (1)
- SLAH3 (1)
- SMART (1)
- SMART version 9 (1)
- SPRED (1)
- SPRED2 (1)
- Schimpanse (1)
- Sentinel-2 (1)
- Sleep fragmentation (1)
- Small-holder agriculture (1)
- Sphingosinanaloga (1)
- Sphingosinkinase (1)
- Spider Silk (1)
- Spinnenseide (1)
- Stammvielfalt (1)
- Staphylococcal infection (1)
- Stp (1)
- Striatum (1)
- Super-resolution microscopy (1)
- Superagonistic antibody (1)
- Synapse (1)
- Synaptic plasticity (1)
- Synaptonemaler Komplex (1)
- Synchronisation (1)
- Systembiologie (1)
- T-cell (1)
- TERB1-TERB2-MAJIN (1)
- Tanzania (1)
- Terminal domains (1)
- Terminale Domaine (1)
- Th1 cells (1)
- Theranostik (1)
- Tp63 (1)
- Transkriptionsfaktor (1)
- TreM monitoring (1)
- Triple co-culture (1)
- Triton X 100 (1)
- TrkB (1)
- Tropical agriculture (1)
- Trypanosomen (1)
- Trypanosomes (1)
- Tsetsefliege (1)
- USP25 (1)
- USP28 (1)
- Verhalten (1)
- Verschränkung (1)
- Wald (1)
- Waldstruktur (1)
- Wespen (1)
- Wilms tumor (1)
- Zellzyklus (1)
- Zentriolen (1)
- abandonment (1)
- abiotic (1)
- acid sphingomyelinase (1)
- acipenseridae (1)
- actin (1)
- acute appendicitis (1)
- acute myeloid leukaemia (1)
- adaptive traits (1)
- adenylate cyclase toxin (1)
- adrenal tumors (1)
- adrenocortical carcinoma (1)
- agri-environment schemes (1)
- agricultural soils (1)
- agriculture (1)
- airway epithelia (1)
- allatostatin‐A (1)
- altitudinal gradient (1)
- alveolar fibrosis (1)
- alveolar regeneration (1)
- alzheimer's disease (1)
- ambrosia beetle (1)
- ambrosia fungi (1)
- amino acid (1)
- amino acid analogues (1)
- amphids (1)
- amphimixis (1)
- ant brain (1)
- antenna (1)
- anthropogenic drivers (1)
- antibiotics (1)
- anticancer activity (1)
- antigenic variation (1)
- antimicrobials (1)
- antiproliferative (1)
- aphids (1)
- apomixis (1)
- approved drugs (1)
- arginine metabolism (1)
- artificial rearing (1)
- automixis (1)
- autophagosomes (1)
- bacteriology (1)
- barcoding (1)
- bark and ambrosia beetles (1)
- bee pollinator (1)
- bees (1)
- behaviour (1)
- biodiversity response (1)
- biodiversity-friendly forest management (1)
- biofluid (1)
- biofuel (1)
- biogenic amines (1)
- biological fluorescence (1)
- biology (1)
- biomanufacturing (1)
- biomimetic 3D tissue model (1)
- bioreactor culture (1)
- biospecies (1)
- birds (1)
- black yeast (1)
- bodies (1)
- body size (1)
- bohemian forest ecosystem (1)
- brain (1)
- brain metastases (1)
- breed predisposition (1)
- bumblebee*s (1)
- butterflies (1)
- c-MYC (1)
- calcium (1)
- calcofluor white staining (1)
- cancer genomics (1)
- cancer predisposition syndromes (1)
- cancer therapy (1)
- cancers (1)
- canine (1)
- carboxylation (1)
- cardiac hypertrophy (1)
- cell biology (1)
- cell surface (1)
- cell surface proteome (1)
- cellular signalling networks (1)
- ceramides (1)
- cerebral metastases (1)
- chaperones (1)
- chemical similarity (1)
- chemokine receptor (1)
- chemotypes (1)
- chlamydia (1)
- chordotonal organ (1)
- chromatin structure (1)
- chromosomes telomere-led movement (1)
- ciliostasis (1)
- circadian rhythms (1)
- clathrin (1)
- click-chemistry (1)
- clinical malformations (1)
- collections (1)
- color lightness (1)
- colorectal cancer (1)
- colour patterns (1)
- combinatorial drug predictions (1)
- community ecology (1)
- compaction (1)
- compatible solutes and other metabolites (1)
- complexome (1)
- computational (1)
- computational biology and bioinformatics (1)
- conformational restriction (1)
- connectomics (1)
- copy numbers (1)
- corazonin (1)
- crop management (1)
- cross pollination (1)
- cryptochrome (1)
- crystallization (1)
- cuticular chemistry (1)
- cuticular hydrocarbons (1)
- cyanine dyes (1)
- cysteine restriction (1)
- cysteine synthase inhibitor (1)
- cytokine release (1)
- cytokinin kinetin (1)
- cytoskeleton (1)
- cytosolic acidification (1)
- cytotoxicity (1)
- data pool (1)
- date palm (1)
- dauer (1)
- deadwood enrichment (1)
- decay (1)
- decoherence (1)
- deep learning–artificial neural network (DL-ANN) (1)
- design (1)
- detoxification (1)
- development (1)
- developmental biology (1)
- developmental differentiation (1)
- diet (1)
- disease (1)
- disturbance gradient (1)
- disturbed humid area (1)
- diversity gradients (1)
- division of labor (1)
- docking (1)
- drug delivery (1)
- drug repurposing (1)
- dry-mounted samples (1)
- ecological intensification (1)
- ecological stoichiometry (1)
- ecosystem services (1)
- ecosystem services; (1)
- electron cryo microscopy (1)
- electron cryo-microscopy (1)
- element translocation (1)
- elementary modes (1)
- elevation (1)
- elevation gradient (1)
- elevational gradient (1)
- encapsulation (1)
- endosomes (1)
- engineering (1)
- entanglement (1)
- enteric glial cells (1)
- enteric nervous system (1)
- entomology (1)
- envelopment (1)
- environmental association analysis (1)
- environmental impact (1)
- environmental justice (1)
- environmental variability (1)
- enzyme (1)
- epithelial cells (1)
- epitope mapping (1)
- ethanol (1)
- evolution; (1)
- evolutionary genetics (1)
- exocytosis (1)
- exotic species (1)
- expansion microscopy (1)
- experiment (1)
- extinction risk (1)
- female reproductive tract (1)
- female-specific (1)
- fertility (1)
- flagellar pocket (1)
- flagellar pocket collar (1)
- flg22 (1)
- flight characteristics (1)
- fluid collectives (1)
- fluorescence imaging (1)
- fluorescent dyes (1)
- fluorescent recombinant vaccinia virus (1)
- flux balance analysis (1)
- flux measurements (1)
- focused ion-beam scanning electron microscopy (1)
- foraging (1)
- foraging activities (1)
- forest biodiversity (1)
- forest ecosystem science (1)
- forestry (1)
- fuel wood (1)
- fullerene (1)
- functional diversity analysis; (1)
- functional traits (1)
- fungal infection model (1)
- fungal rhodopsins (1)
- fusion and fission (1)
- gametogenesis (1)
- gene prediction (1)
- genetic code expansion (1)
- genetic diversity (1)
- genetic markers (1)
- genomic integrity (1)
- genomic traits (1)
- genus Aspergillus (1)
- germination speed (1)
- glioblastoma (1)
- global biomes (1)
- glycophyte Arabidopsis (1)
- glycosphingolipids (1)
- grassland ecology (1)
- graviception (1)
- grazing (1)
- greenhouse gases (1)
- guard cell (1)
- guard cells (1)
- gut barrier (1)
- gynogenesis (1)
- habitat availability (1)
- half-lives (1)
- halophyte Thellungiella/Eutrema (1)
- hemiptera (1)
- hepatitis B core protein (1)
- hepatitis B virus (1)
- herbivorous beetles (1)
- herbivory (1)
- heterogeneous background (1)
- high-confidence proteome (1)
- high-resolution imaging (1)
- hippocampal (1)
- homeostasis (1)
- homocysteine (1)
- honey bee (1)
- honey bees and native bees (1)
- honeybee*s (1)
- hook complex (1)
- host cells (1)
- host specificity (1)
- host–parasitoid interaction (1)
- human airway mucosa tissue models (1)
- human cells (1)
- human genomics (1)
- human induced pluripotent stem cell (hiPSC) (1)
- human nasal epithelial cells (1)
- human pathogenic fungi (1)
- human tracheo-bronchial epithelial cells (1)
- hybridogenesis (1)
- hypoxia (1)
- imaging the immune system (1)
- immune epitope mapping (1)
- immune genes (1)
- immune organs (1)
- immune system (1)
- immunotherapies (1)
- immunotherapy (1)
- in vitro (1)
- in vivo toxicity (1)
- in-silico model (1)
- infection spread (1)
- infectious diseases (1)
- inflammation (1)
- inflammatory bowel disease (1)
- insect (1)
- insect brain (1)
- insect decline (1)
- insect standard brain atlas (1)
- insect tracking (1)
- insights (1)
- interactome (1)
- intercellular junctions (1)
- interferon γ (1)
- intestinal epithelial barrier (1)
- intracellular (1)
- intracellular bacterial pathogens (1)
- intracellular pathogens (1)
- invasiveness (1)
- ion signaling (1)
- ion transport (1)
- ionotropic glutamate receptors (1)
- island biogeography (1)
- iterative shape averaging (1)
- juvenile hormone (1)
- kinetics (1)
- land use intensification (1)
- landscape heterogeneity (1)
- laparoscopic appendectomy (1)
- latency (1)
- latitudinal gradient (1)
- learning and memory (1)
- lethality rate (1)
- life cycle (1)
- ligand binding domain (1)
- ligand-gated ion channels (1)
- light stimuli (1)
- limiting dilution cloning (1)
- liquid chromatography/mass spectrometry (1)
- lncRNAs (1)
- local adaptation (1)
- long non-coding RNA (1)
- low-secretion phenotype mutants (1)
- lung cancer (1)
- lysosomal recruitment (1)
- m7G cap (1)
- mRNA (1)
- mRNA cap (1)
- mRNA decapping (1)
- macro moths (1)
- macro- and micro-elements (1)
- magnetic compass (1)
- malignant tumors (1)
- maturation signal (1)
- mean fruit body size (1)
- measles (1)
- mechanisms of persister formation (1)
- mechanistic model (1)
- medaka (1)
- median and dorsal raphe (1)
- meiotic prophase (1)
- melanoma (1)
- melanoma dedifferentiation (1)
- membrane fission (1)
- membrane recycling (1)
- membrane trafficking (1)
- menstrual cycles (1)
- meta-analysis (1)
- metabolic adaptation (1)
- metabolic modeling (1)
- metabolome (1)
- metabolomic profiling (1)
- metabolomics (1)
- metagenomics (1)
- methylation (1)
- miR-30 (1)
- miRNA processing (1)
- mice (1)
- microbes (1)
- microbial community abundance and compositions (1)
- microbial ecology and evolution (1)
- microbial rhodopsins (1)
- microbiology (1)
- microbiology techniques (1)
- microbiome (1)
- microbiome metabarcoding (1)
- microhabitats (1)
- microscopy (1)
- microswimming (1)
- microtubule cytoskeleton (1)
- mikrobielle Ökologie und Evolution (1)
- mikroskopische Untersuchung (1)
- mixed-species forestry (1)
- model (1)
- modular tumor tissue models (1)
- modulation (1)
- modulatory effects (1)
- module search (1)
- molecular biology (1)
- molecular conformation (1)
- molecular dynamics simulation (1)
- molecular evolution (1)
- molecular modeling (1)
- molecular neuroscience (1)
- monoclonal stable cell (1)
- monolayer (1)
- moon (1)
- more-individuals hypothesis (1)
- morphometry (1)
- mossy fiber synapses (1)
- motile behaviour (1)
- motility (1)
- mouse model (1)
- movement ecology (1)
- multisensory integration (1)
- multispecies studies (1)
- mushroom bodies (1)
- mushroom body (1)
- mushroom body calyx (1)
- mutation screening (1)
- mutualism (1)
- nanocarrier (1)
- nanotube formation (1)
- nanovesicle formation (1)
- natural enemies (1)
- natural enemy (1)
- natural environment (1)
- naturalized species (1)
- navigation (1)
- ncuCyte\(^®\)S3 (1)
- neo-Y (1)
- nephroblastoma (1)
- nephroblastomatosis (1)
- nesting ecology (1)
- network biology (1)
- neural networks (1)
- neuroblast growth (1)
- neuroblastoma (1)
- neuroethology (1)
- neuropeptidomics (1)
- neuropils (1)
- neuropsychiatric disorders (1)
- neuroscience (1)
- neurospheres (1)
- neurotransmitter (1)
- neurotrophic factors (1)
- neutral theory (1)
- neutrophil transmigration (1)
- niche partitioning (1)
- non-small cell lung cancer (1)
- novel disturbance (1)
- nucleolus (1)
- nursing (1)
- octopamine (1)
- oil bees (1)
- olfactory learning (1)
- olive (1)
- open appendectomy (1)
- optic lobes (1)
- optogenetics (1)
- organic amendment (1)
- organoid (1)
- organoids (1)
- outcome (1)
- overstory (1)
- painted nest preference (1)
- pangenome (1)
- parabiosis (1)
- parallel evolution (1)
- parasite evolution (1)
- parasite genetics (1)
- parthenogenesis (1)
- pathogenicity (1)
- patient-derived organoid (PDOs) (1)
- patient-derived tumor organoid (PDTO) (1)
- pediatric adrenocortical adenoma (1)
- pediatric adrenocortical cancer (1)
- pediatric adrenocortical tumor (1)
- peptide inhibitor of envelopment (1)
- peptide microarray (1)
- perception (1)
- perfusion-based bioreactor system (1)
- period (1)
- persistence (1)
- pests (1)
- phenological escape (1)
- phenology (1)
- phosphorylation (1)
- photodynamic therapy (1)
- photoperiodism (1)
- photoreceptor (1)
- photorespiration (1)
- phototaxis (1)
- phylogenetic analysis (1)
- phylogenetic inertia (1)
- phylogenetische Trägheit (1)
- phytophagous beetles (1)
- plant ecology (1)
- plant functional traits (1)
- plant growth (1)
- plant invasion (1)
- plant–pollinator interaction (1)
- plaque assay (1)
- plaque isolation (1)
- platform (1)
- pocket factor (1)
- policy (1)
- pollen (1)
- pollen limitation (1)
- pollen metabarcoding (1)
- pollen tube (1)
- pollination (1)
- pollinator (1)
- polyethism (1)
- polymorphism (1)
- polyploidy (1)
- population coverage (1)
- population divergence (1)
- positive selection (1)
- post-disturbance logging (1)
- predation (1)
- pregnancy (1)
- presynaptic plasticity (1)
- primate (1)
- pro-oxidant (1)
- prognostic factors (1)
- proliferation (1)
- prolonged survival (1)
- protein crowding (1)
- protein domain architectures (1)
- protein domains (1)
- protein translocation (1)
- proton channel (1)
- protozoan (1)
- pyrazolo[3,4-d]pyrimidine (1)
- quantum computing (1)
- qubit (1)
- rapid evolution (1)
- real-time (1)
- reception (1)
- recombination (1)
- reconstruction (1)
- red lists (1)
- regime shift (1)
- regulation (1)
- regulation of gene expression (1)
- release (1)
- remote sensing (1)
- remote sensing‐enabled essential biodiversity variables (1)
- reproductive health (1)
- respiratory chain (1)
- retinoic acid (1)
- retrotransposons (1)
- reveals (1)
- ribosome biogenesis (1)
- riboswitch (1)
- risk management (1)
- rocus sieberi (1)
- salinity (1)
- salt stress (1)
- saprobic and ectomycorrhizal basidiomycetes (1)
- saproxylic beetles (1)
- scaffold search (1)
- secondary site infection (1)
- serotonin-specific neurons (1)
- sex chromosomes (1)
- sex determination (1)
- shoot–root interaction (1)
- short‐rotation coppice (1)
- shrub‐cover (1)
- signaling pathway (1)
- silkworm (1)
- single molecule localization microscopy (1)
- single strand blocking (1)
- single-molecule biophysics (1)
- single-molecule fluorescence spectroscopy (1)
- sky compass (1)
- sleeping sickness (1)
- smORFs (1)
- social insect (1)
- social insects (1)
- soil (1)
- soil characteristics (1)
- spanlastic (1)
- specialists (1)
- specialization (1)
- species as individuals (1)
- species as natural kinds (1)
- species coexistence mechanism (1)
- species concept (1)
- species diversity (1)
- species problem (1)
- species richness (1)
- spermatogenesis (1)
- spermatogenic cell sorting (1)
- sphingolipids (1)
- sphingomyelinase (1)
- sphingomyelinase release (1)
- sphingosine (1)
- sphingosine 1-phosphate (1)
- spotted knifejaw (1)
- squamous (1)
- standing variation (1)
- staphylococcal alpha-toxin (1)
- stoichiometry (1)
- stomata (1)
- stomatal conductance (1)
- strain diversity (1)
- stress conditions (1)
- structural biology (1)
- structural synaptic plasticity (1)
- subungual (1)
- sucrose responsiveness (1)
- sulfate (1)
- super-resolution (1)
- super-resolution array tomography (1)
- super-resolution microscopy (SRM) (1)
- sustainable intensification (1)
- symbiont selection (1)
- synapse formation (1)
- synaptic complexes (1)
- synaptic plasticity (1)
- synthetic pathways (1)
- systematic review (1)
- systems biology (1)
- tachykinin (1)
- temperature (1)
- temporal development (1)
- temporal mismatch (1)
- therapy (1)
- tight junction (1)
- time lapse cameras (1)
- tissue model (1)
- toe (1)
- tool (1)
- tool-use (1)
- total internal reflection microscopy (1)
- tracheal cytotoxin (1)
- trachomatis (1)
- trade‐offs (1)
- trait-based management (1)
- transcriptional regulation (1)
- transcriptome (1)
- transmission (1)
- transposable elements (1)
- triglycerides (1)
- trypanosome (1)
- tumor (1)
- tumor disease (1)
- tumor surveillance (1)
- tumour immunology (1)
- type I interferon (1)
- tyramine (1)
- ultrasound vocalizations (1)
- understory (1)
- urban greening (1)
- variant surface glycoproteins (1)
- vascular plants (1)
- vector-parasite interaction (1)
- vertical mismatch (1)
- vesicles (1)
- virus reactivation (1)
- visual system (1)
- wasps (1)
- water quality (1)
- wheat yield (1)
- whole-genome analysis (1)
- wind compass (1)
- yvcK/glmR operon (1)
- Ökologie (1)
- Ökosystemdienstleistung (1)
- ΔNp63 (1)
Institute
- Theodor-Boveri-Institut für Biowissenschaften (187) (remove)
Sonstige beteiligte Institutionen
Chlamydia trachomatis, an obligate intracellular human pathogen, is the world’s leading cause of infection related blindness and the most common, bacterial sexually transmitted disease. In order to establish an optimal replicative niche, the pathogen extensively interferes with the physiology of the host cell. Chlamydia switches in its complex developmental cycle between the infectious non-replicative elementary bodies (EBs) and the non-infectious replicative reticulate bodies (RBs). The transformation to RBs, shortly after entering a host cell, is a crucial process in infection to start chlamydial replication. Currently it is unknown how the transition from EBs to RBs is initiated. In this thesis, we could show that, in an axenic media approach, L glutamine uptake by the pathogen is crucial to initiate the EB to RB transition. L-glutamine is converted to amino acids which are used by the bacteria to synthesize peptidoglycan. Peptidoglycan inturn is believed to function in separating dividing Chlamydia. The glutamine metabolism is reprogrammed in infected cells in a c-Myc-dependent manner, in order to accomplish the increased requirement for L-glutamine. Upon a chlamydial infection, the proto-oncogene c-Myc gets upregulated to promote host cell glutaminolysis via glutaminase GLS1 and the L-glutamine transporter SLC1A5/ASCT2. Interference with this metabolic reprogramming leads to limited growth of C. trachomatis. Besides the active infection, Chlamydia can persist over a long period of time within the host cell whereby chronic and recurrent infections establish. C. trachomatis acquire a persistent state during an immune attack in response to elevated interferon-γ (IFN-γ) levels. It has been shown that IFN-γ activates the catabolic depletion of L-tryptophan via indoleamine 2,3-dioxygenase (IDO), resulting in the formation of non-infectious atypical chlamydial forms. In this thesis, we could show that IFN-γ depletes the key metabolic regulator c-Myc, which has been demonstrated to be a prerequisite for chlamydial development and growth, in a STAT1-dependent manner. Moreover, metabolic analyses revealed that the pathogen de routs the host cell TCA cycle to enrich pyrimidine biosynthesis. Supplementing pyrimidines or a-ketoglutarate helps the bacteria to partially overcome the persistent state. Together, the results indicate a central role of c-Myc induced host glutamine metabolism reprogramming and L-glutamine for the development of C. trachomatis, which may provide a basis for anti-infectious strategies. Furthermore, they challenge the longstanding hypothesis of L-tryptophan shortage as the sole reason for IFN-γ induced persistence and suggest a pivotal role of c-Myc in the control of the C. trachomatis dormancy.
The Myb-MuvB (MMB) complex plays an essential role in the time-dependent transcriptional activation of mitotic genes. Recently, our laboratory identified a novel crosstalk between the MMB-complex and YAP, the transcriptional coactivator of the Hippo pathway, to coregulate a subset of mitotic genes (Pattschull et al., 2019). Several genetic studies have shown that the Hippo-YAP pathway is essential to drive cardiomyocyte proliferation during cardiac development (von Gise et al., 2012; Heallen et al., 2011; Xin et al., 2011). However, the exact mechanisms of how YAP activates proliferation of cardiomyocytes is not known. This doctoral thesis addresses the physiological role of the MMB-Hippo crosstalk within the heart and characterizes the YAP-B-MYB interaction with the overall aim to identify a potent inhibitor of YAP.
The results reported in this thesis indicate that complete loss of the MMB scaffold protein LIN9 in heart progenitor cells results in thinning of ventricular walls, reduced cardiomyocyte proliferation and early embryonic lethality. Moreover, genetic experiments using mice deficient in SAV1, a core component of the Hippo pathway, and LIN9-deficient mice revealed that the correct function of the MMB complex is critical for proliferation of cardiomyocytes due to Hippo-deficiency. Whole genome transcriptome profiling as well as genome wide binding studies identified a subset of Hippo-regulated cell cycle genes as direct targets of MMB. By proximity ligation assay (PLA), YAP and B-MYB were discovered to interact in embryonal cardiomyocytes. Biochemical approaches, such as co-immunoprecipitation assays, GST-pulldown assays, and µSPOT-based peptide arrays were employed to characterize the YAP-B-MYB interaction. Here, a PY motif within the N-terminus of B-MYB was found to directly interact with the YAP WW-domains. Consequently, the YAP WW-domains were important for the ability of YAP to drive proliferation in cardiomyocytes and to activate MMB target genes in differentiated C2C12 cells. The biochemical information obtained from the interaction studies was utilized to develop a novel competitive inhibitor of YAP called MY-COMP (Myb-YAP competition). In MY-COMP, the protein fragment of B-MYB containing the YAP binding domain is fused to a nuclear localization signal. Co-immunoprecipitation studies as well as PLA revealed that the YAP-B-MYB interaction is robustly blocked by expression of MY-COMP. Adenoviral overexpression of MY-COMP in embryonal cardiomyocytes suppressed entry into mitosis and blocked the pro-proliferative function of YAP. Strikingly, characterization of the cellular phenotype showed that ectopic expression of MY-COMP led to growth defects, nuclear abnormalities and polyploidization in HeLa cells.
Taken together, the results of this thesis reveal the mechanism of the crosstalk between the Hippo signaling pathway and the MMB complex in the heart and form the basis for interference with the oncogenic activity of the Hippo coactivator YAP.
Nutrition facts of pollen: nutritional quality and how it affects reception and perception in bees
(2021)
Nutrients belong to the key elements enabling life and influencing an organism’s fitness. The intake of nutrients in the right amounts and ratios can increase fitness; strong deviations from the optimal intake target can decrease fitness. Hence, the ability to assess the nutritional profile of food would benefit animals. To achieve this, they need the according nutrient receptors, the ability to interpret the receptor information via perceptive mechanisms, and the ability to adjust their foraging behavior accordingly. Additionally, eventually existing correlations between the nutrient groups and single nutrient compounds in food could help them to achieve this adjustment. A prominent interaction between food and consumer is the interaction between flowering plants (angiosperms) and animal pollinators. Usually both of the interacting partners benefit from this mutualistic interaction. Plants are pollinated while pollinators get a (most of the times) nutritional reward in form of nectar and/or pollen. As similar interactions between plants and animals seem to have existed even before the emergence of angiosperms, these interactions between insects and angiosperms very likely have co-evolved right from their evolutionary origin. Therefore, insect pollinators with the ability to assess the nutritional profile may have shaped the nutritional profile of plant species depending on them for their reproduction via selection pressure. In Chapter I of this thesis the pollen nutritional profile of many plant species was analyzed in the context of their phylogeny and their dependence on insect pollinators. In addition, correlations between the nutrients were investigated. While the impact of phylogeny on the pollen protein content was little, the mutual outcome of both of the studies included in this chapter is that protein content of pollen is mostly influenced by the plant’s dependence on insect pollinators. Several correlations found between nutrients within and between the nutrient groups could additionally help the pollinators to assess the nutrient profile of pollen. An important prerequisite for this assessment would be that the pollinators are able to differentiate between pollen of different plant species. Therefore, in Chapter II it was investigated whether bees have this ability. Specifically, it was investigated whether honeybees are able to differentiate between pollen of two different, but closely related plant species and whether bumblebees prefer one out of three pollen mixes, when they were fed with only one of them as larvae. Honeybees indeed were able to differentiate between the pollen species and bumblebees preferred one of the pollen mixes to the pollen mix they were fed as larvae, possibly due to its nutritional content. Therefore, the basis for pollen nutrient assessment is given in bees. However, there also was a slight preference for the pollen fed as larvae compared to another non-preferred pollen mix, at least hinting at the retention of larval memory in adult bumblebees. Chapter III looks into nutrient perception of bumblebees more in detail. Here it was shown that they are principally able to perceive amino acids and differentiate between them as well as different concentrations of the same amino acid. However, they do not seem to be able to assess the amino acid content in pollen or do not focus on it, but instead seem to focus on fatty acids, for which they could not only perceive concentration differences, but also were able to differentiate between. These findings were supported by feeding experiments in which the bumblebees did not prefer any of the pollen diets containing less or more amino acids but preferred pollen with less fatty acids. In no choice feeding experiments, bumblebees receiving a diet with high fatty acid content accepted undereating other nutrients instead of overeating fat, leading to increased mortality and the inability to reproduce. Hence, the importance of fat in pollen needs to be looked into further. In conclusion, this thesis shows that the co-evolution of flowering plants and pollinating insects could be even more pronounced than thought before. Insects do not only pressure the plants to produce high quality nectar, but also pressure those plants depending on insect pollination to produce high quality pollen. The reason could be the insects’ ability to receive and perceive certain nutrients, which enables them to forage selectively leading to a higher reproductive success of plants with a pollinator-suitable nutritional pollen profile.
Insects are responsible for the major part of the ecosystem services pollination and natural pest control. If insects decline, these ecosystem services can not longer be reliably delivered. Agricultural intensification and the subsequent loss and fragmentation of habitats has among others been identified to cause insect decline. Ecological intensification aims to promote alternative and sustainable management practices in agricultural farming, for example to decrease the use of external inputs such as pesticides. Agri-environment schemes make amends for farmers if they integrate ecologically beneficial measures into their farming regime and can therefore promote ecological intensification. There is a wide variety of agri-environment schemes, but the implementation of sown flower fields on crop fields is often included. Flower fields offer foraging resources as well as nesting sites for many different insect species and should be able to support insect populations as well as to increase ecosystem services to adjacent fields. However, the potential of flower fields to exhibit these effects is depending on many factors. Among others, the age and size of the flower field can influence if and how different insects profit from the measure. Additionally, the complexity of the surrounding landscape and therefore the existing biodiversity is influencing the potential of flower fields to increase ecosystem services locally. The goal of this study is to disentangle to which degree these factors influence the ecosystem services pollination and natural pest control and if these factors interact with each other. Furthermore, it will be examined if and how flower fields and ecosystem services influence crop yield. Additional factors examined in this study are distance decay and pesticide use. The abundance of beneficial insects can decrease strongly with increasing distance to suitable habitats. Pesticide use in turn could abrogate positive effects of flower fields on beneficial insects.
To examine these different aspects and to be able to make recommendations for flower field implementation, field experiments were conducted on differently composed sown flower fields and adjacent oilseed rape fields. Flower fields differed in their age and continuity as well as in their size. Additionally, flower and oilseed rape fields were chosen in landscapes with different amounts of semi-natural habitat. Oilseed rape fields adjacent to calcareous grasslands and conventional crop fields served as controls. Pollinator observations and pollen beetle and parasitism surveys were conducted in the oilseed rape fields. Additionally, different yield parameters of the oilseed rape plants were recorded. Observations were conducted and samples taken in increasing distance to the flower fields to examine distance decay functions. Spray windows were established to inspect the influence of pesticides on ecosystem services and crop yields. Linear mixed models were used for statistical analysis.
The results show, that newly established flower fields with high amounts of flower cover are very attractive for pollinators. If the flower fields reached a certain size (> 1.5ha), the pollinators tended to stay in these fields and did not distribute into the surroundings. High amounts of semi-natural habitat in the surrounding landscape increased the value of small flower fields as starting points for pollinators and their subsequent spillover into crop fields. Additionally, high amounts of semi-natural habitat decreased the decay of pollinators with increasing distance to the flower fields. Based on these results, it can be recommended to establish many small flower fields in landscapes with high amounts of semi-natural habitat and large flower fields in landscapes with low amounts of semi-natural habitat. However, it is mentionable that flower fields are no substitute for perennial semi-natural habitats. These still must be actively conserved to increase pollination to crop fields.
Furthermore, the lowest amount of pollen beetle infestation was found on oilseed rape fields adjacent to continuous flower fields aged older than 6 years. Flower fields and calcareous grasslands in general increased pollen beetle parasitism in adjacent oilseed rape fields compared to conventional crop fields. The threshold for effective natural pest control could only be reached in the pesticide free areas in the oilseed rape fields adjacent to continuous flower fields and calcareous grasslands. Parasitism and superparasitism declined with increasing distance to the adjacent fields in pesticide treated areas of the oilseed rape fields. However, they remained on a similar level in spray windows without pesticides. Large flower fields increased parasitism and superparasitism more than small flower fields. Flower fields generally have the potential to increase pollen beetle parasitism rates, but pesticides can abrogate these positive effects of flower fields on natural pest control.
Last but not least, effects of flower fields and ecosystem services on oilseed rape yield were examined. No positive effects of pollination on oilseed rape yield could be found. Old and continuous flower fields increased natural pest control in oilseed rape fields, which in turn increased seed set and total seed weight of oilseed rape plants. The pesticide treatment had negative effects on natural pest control, but positive effects on crop yield. Pollination and natural pest control decreased with increasing distance to the field edge, but fruit set slightly increased. The quality of the field in terms of soil and climatic conditions did not influence the yield parameters examined in this study. Yield formation in oilseed rape plants is a complex process with many factors involved, and it is difficult to disentangle indirect effects of flower fields on yield. However, perennial flower fields can promote ecological intensification by increasing crop yield via natural pest control. This study contributes to a better understanding of the effects of differently composed flower fields on pollination, natural pest control and oilseed rape yield.
Analysis of \(Trypanosoma\) \(brucei\) motility and the infection process in the tsetse fly vector
(2021)
African trypanosomes are protist pathogens that are infective for a wide spectrum of mammalian hosts. Motility has been shown to be essential for their survival and represents an important virulence factor. Trypanosoma brucei is transmitted by the bite of the bloodsucking tsetse fly, the only vector for these parasites. The voyage through the fly is complex and requires several migration, proliferation and differentiation steps, which take place in a defined order and in specific fly tissues.
The first part of this doctoral thesis deals with the establishment of the trypanosome tsetse system as a new model for microswimmer analysis. There is an increasing interdisciplinary interest in microbial motility, but a lack of accessible model systems. Therefore, this work introduces the first enclosed in vivo host parasite system that is suitable for analysis of diverse microswimmer types in specific microenvironments. Several methods were used and adapted to gain unprecedented insights into trypanosome motion, the fly´s interior architecture and the physical interaction between host and parasite. This work provides a detailed overview on trypanosome motile behavior as a function of development in diverse host surroundings. In additional, the potential use of artificial environments is shown. This can be used to partly abstract the complex fly architecture and analyze trypanosome motion in defined nature inspired geometries.
In the second part of the thesis, the infection of the tsetse fly is under investigation. Two different trypanosome forms exist in the blood: proliferative slender cells and cell cycle arrested stumpy cells. Previous literature states that stumpy cells are pre adapted to survive inside the fly, whereas slender cells die shortly after ingestion. However, infection experiments in our laboratory showed that slender cells were also potentially infective. During this work, infections were set up so as to minimize the possibility of stumpy cells being ingested, corroborating the observation that slender cells are able to infect flies. Using live cell microscopy and fluorescent reporter cell lines, a comparative analysis of the early development following infection with either slender or stumpy cells was performed. The experiments showed, for the first time, the survival of slender trypanosomes and their direct differentiation to the procyclic midgut stage, contradicting the current view in the field of research. Therefore, we can shift perspectives in trypanosome biology by proposing a revised life cycle model of T. brucei, where both bloodstream stages are infective for the vector.
Insight into molecular mechanisms of folding and self-association of spider silk protein domains
(2021)
Spider silk is a biomaterial of extraordinary toughness paired with elasticity. The assembly of silk proteins, so-called spidroins (from “spider” and “fibroin”), generates the silk threads we typically see in our garden or the corners of our houses. Although spider webs from different species vary considerably in geometry and size, many sections of spidroin sequences are conserved. Highly conserved regions, found in all spidroins, relate to the terminal domains of the protein, i.e., the N-terminal (NTD) and C-terminal domains (CTD). Both have an essential function in the silk fibre association and polymerisation.
The NTD is a 14 kDa five-helix bundle, which self-associates via a pH-driven mechanism. This process is critical for starting the polymerisation of the fibre. However, detailed insights into how conserved this mechanism is in different species and the quantitative thermodynamic comparison between homologous NTDs was missing. For this reason, four homologous NTDs of the major ampullate gland (MaSp) from spider species Euprosthenops australis, Nephila clavipes, Latrodectus hesperus, and Latrodectus geometricus were investigated. I analysed and quantified equilibrium thermodynamics, kinetics of folding, and self-association. Methods involved dynamic light scattering (MALS), stopped-flow fluorescence and circular dichroism spectroscopy in combination with thermal and chemical denaturation experiments. The results showed conserved, cooperative two-state folding on a sub-millisecond time scale. All homologous NTDs showed a similarly fast association in the order of 10^9 M^−1 s^−1, while the resulting equilibrium dissociation constants were in the low nanomolar range. Electrostatic forces were found to be of great importance for protein association. Monomeric protein stability increased with salt concentration while enhancing its folding speed. However, due to Debye-Hückel effects, we found intermolecular electrostatics to be shielded, which reduced the NTDs association capacity significantly at high ionic strength. Altogether, the energetics and kinetics of the NTD dimerisation was conserved for all analysed homologs.
Comparable to the NTD, the spider silks CTD is also a α-helix bundle, which covalently links two spidroins. The orientation of the domains predetermines the future fibre geometry. Here again, the detailed quantitative characterisation of the folding and dimerisation was missing. Therefore, the CTD from the E. australis was analysed in-depth. The protein folded via a three-state mechanism and was placed in the family of knotted proteins.
By analysing the amino acid composition of the NTD of the MaSp1 of the Euprosthenops australis, we found an unusually high content of methionine residues (Met). To elucidate why this protein exhibits so many Met residues, I mutated all core Mets simultaneously to leucine (Leu). Results revealed a dramatically stabilised NTD, which now folded 50 times faster. After solving the tertiary structure of the mutant by NMR (nuclear magnetic resonance) spectroscopy, the structure of the monomeric mutant was found to be identical with the wild-type protein. However, when probing the dimerisation of the NTD, I could show that the association capacity was substantially impaired for the mutant. Our findings lead to the conclusion that Met provides the NTD with enhanced conformational dynamics and thus mobilises the protein, which results in tightly associated dimers. In additional experiments, I first re-introduced new Met residues into the Met-depleted protein at sequence positions containing native Leu. Hence, the mutated NTD protein was provided with the same number of Leu, which were previously removed by mutation. However, the protein did not regain wild-type characteristics. The functionality was not restored, but its stability was decreased as expected. To probe our hypothesis gained from the MaSp NTD, I transferred the experiment to another protein, namely the Hsp90 chaperone. Therefore, I incorporated methionine residues in the protein, which resulted in a slight improvement of its function.
Finally, trial experiments were performed aiming at the synthesis of shortened spidroin constructs containing less repetitive middle-segments than the wild-type protein. The objective was to study the findings of the terminal domains in the context of an intact spidroin. The synthesis of these engineered spidroins was challenging. Nevertheless, preliminary results encourage the assumption that the characteristics observed in the isolated domains hold true in the context of a full-length spidroin.
Because of its complexity and intricacy, studying the nervous system is often challenging. Fortunately, the small nematode roundworm Caenorhabditis elegans is well established as a model system for basic neurobiological research. The C. elegans model is also the only organism with a supposedly complete connectome, an organism-wide map of synaptic connectivity resolved by electron microscopy, which provides some understanding of how the nervous system works as a whole. However, the number of available data-sets is small and the connectome contains errors and gaps. One example of this concerns electrical synapses. Electrical synapses are formed by gap junctions and difficult to map due to their often ambiguous morphology in electron micrographs, leading to misclassification or omission. On the other hand, chemical synapses are more easily mapped, but many aspects of their mode of operation remain elusive and their role in the C. elegans connectome is oversimplified. A comprehensive understanding of signal transduction of neurons between each other and other cells will be indispensable for a comprehensive understanding of the nervous system. In this thesis, I approach these challenges with a combination of advanced light and electron microscopy techniques.
First, this thesis describes a strategy to increase synaptic specificity in connectomics. Specifically, I classify gap junctions with a high degree of confidence. To achieve this, I utilized array tomography (AT). In this thesis, AT is adapted for high-pressure freezing to optimize for structure preservation and for super-resolution light microscopy; in this manner, I aim to bridge the gap between light and electron microscopy resolutions. I call this adaptation super-resolution array tomography (srAT). The srAT approach made it possible to clearly identify and map gap junctions with high precision and accuracy. The results from this study showcased the feasibility of incorporating electrical synapses into connectomes in a systematic manner, and subsequent studies have used srAT for other models and questions.
As mentioned above, the C. elegans connectomic model suffers from a shortage of datasets. For most larval stages, including the special dauer larval stage, connectome data is completely missing up to now. To obtain the first partial connectome data-set of the C. elegans dauer larva, we used focused ion-beam scanning electron microscopy (FIB-SEM). This technique offers an excellent axial resolution and is useful for acquiring large volumes for connectomics. Together with our collaborators, I acquired several data-sets which enable the analysis of dauer stage-specific “re-wiring” of the nervous system and thus offer valuable insights into connectome plasticity/variability.
While chemical synapses are easy to map relative to electrical synapses, signal transduction via chemical transmitters requires a large number of different proteins and molecular processes acting in conjunction in a highly constricted space. Because of the small spatial scale of the synapse, investigating protein function requires very high resolution, which electron tomography provides. I analyzed electron tomograms of a worm-line with a mutant synaptic protein, the serine/threonine kinase SAD-1, and found remarkable alterations in several architectural features. My results confirm and re-contextualize previous findings and provide new insight into the functions of this protein at the chemical synapse.
Finally, I investigated the effectiveness of our methods on “malfunctioning,” synapses, using an amyotrophic lateral sclerosis (ALS) model. In the putative synaptopathy ALS, the mechanisms of motor neuron death are mostly unknown. However, mutations in the gene FUS (Fused in Sarcoma) are one known cause of the disease. The expression of the mutated human FUS in C. elegans was recently shown to produce an ALS-like phenotype in the worms, rendering C. elegans an attractive disease model for ALS. Together with our collaboration partners, I applied both srAT and electron tomography methods to “ALS worms” and found effects on vesicle docking. These findings help to explain electrophysiological recordings that revealed a decrease in frequency of mini excitatory synaptic currents, but not amplitudes, in ALS worms compared to controls. In addition, synaptic endosomes appeared larger and contained electron-dense filaments in our tomograms. These results substantiate the idea that mutated FUS impairs vesicle docking and also offer new insights into further molecular mechanisms of disease development in FUS-dependent ALS. Furthermore, we demonstrated the broader applicability of our methods by successfully using them on cultured mouse motor neurons.
Overall, using the C. elegans model and a combination of light and electron microscopy methods, this thesis helps to elucidate the structure and function of neuronal synapses, towards the aim of obtaining a comprehensive model of the nervous system.
The human pathogen Chlamydia trachomatis is the main cause of sexually transmitted infections worldwide. The obligate intracellular bacteria are the causative agent of several diseases that reach from conjunctivitis causing trachoma and blindness as well as salpingitis and urethritis which can lead to infertility if left untreated.
In order to gain genetically engineered Chlamydia that inducible knock down specific gene expression, the CRISPRi system was established in C. trachomatis. In a proof of principle experiment it was shown that C. trachomatis pCRISPRi:gCdu1III target ChlaDUB1 expression and reduce the protein amount up to 50 %. Knock-down of the DUB did not influence protein levels of anti-apoptotic Mcl-1 and did not make cells susceptible for apoptosis. However, reduced dCas9 protein size, bacterial growth impairment and off target effects interfering with the GFP signal, form obstacles in CRISPRi system in Chlamydia. For routinely use of the CRISPRi method in C. trachomatis further investigation is needed.
Since the bacterial life cycle includes two morphological and functional distinct forms, it is essential for chlamydial spread to complete the development cycle and form infectious progeny. Therefore, Chlamydia has evolved strategies to evade the host immune system in order to stay undetected throughout the developmental cycle. The bacteria prevent host cell apoptosis via stabilization of anti-apoptotic proteins like Mcl-1, Survivin and HIF-1α and activate pro-survival pathways, inhibiting invasion of immune cells to the site of infection. The host cell itself can destroy intruders via cell specific defense systems that involve autophagy and recruitment of professional immune cells. In this thesis the role of the chlamydial deubiuqitinase ChlaDUB1 upon immune evasion was elucidated. With the mutant strain Ctr Tn-cdu1 that encodes for a truncated DUB due to transposon insertion, it was possible to identify ChlaDUB1 as a potent opponent of the autophagic system. Mutant inclusions were targeted by K48 and K63 chain ubiquitination. Subsequently the inclusion was recognized by autophagic receptors like p62, NBR1 and NDP52 that was reversed again by complementation with the active DUB. Xenophagy was promoted so far as LC3 positive phagosomes formed around the inclusion of Ctr Tn-cdu1, which did not fuse with the lysosome. The detected growth defect in human primary cells of Chlamydia missing the active DUB was not traced back to autophagy, but was due to impaired development and replication. It was possible to identify Ankib1, the E3 ligase, that ubiquitinates the chlamydial inclusion in a siRNA based screen. The activating enzyme Ube1 and the conjugating enzyme Ube2L3 are also essential in this process. Chlamydia have a reduced genome and depend on lipids and nutrients that are translocated from the host cell to the inclusion to proliferate. Recruitment of fragmented Golgi stacks to the inclusion surface was prevented when ChlaDUB1 was inactive, probably causing diminished bacterial growth. Additionally, the modification of the inclusion by Ankib1 and subsequent decoration by autophagic markers was not only present in human but also murine cells. Comparison of other Chlamydia strains and species revealed Ankib1 to be located at the proximity of the inclusion in C. trachomatis strains only but not in C. muridarum or C. pneumoniae, indicating that Ankib1 is specifically the E3 ligase of C. trachomatis. Moreover, the role of ChlaDUB1 in infected tissue was of interest, since ChlaDUB1 protein was also found in early EB stage and so might get in contact with invading immune cells after cell lysis. While bacteria spread and infect new host cells, Chlamydia can also infect immune cells. Infection of human neutrophils with Ctr Tn-cdu1 shows less bacterial survival and affirms the importance of the DUB for bacterial fitness in these cells.
One of the fascinating features of meiotic prophase I, is the highly conserved
vigorous movements of homologous chromosomes. These movements are
critical for the success of essential events as homologs alignment, synapsis and
recombination. Several organisms studied so far, including mammals, worms,
yeast and plants achieve these movements by anchoring the chromosome ends
to specialized sites in the nuclear envelope (NE). This attachment requires
telomere adaptor proteins which have to date been identified in fission yeast
and mice.
The mouse meiosis-specific telomere adaptor proteins TERB1, TERB2, and
MAJIN are involved in the attachment of ubiquitous shelterin telomere to the
LINC complex, in an analogous mechanism as those described in fission yeast.
Despite the essential role of meiosis-specific telomere adaptor proteins, the
precise mechanism of anchorage of telomeres to the nuclear envelope, as well
as their evolutionary history, are still not well understood. Therefore, the main
aim of this thesis is to investigate the organization of the mouse meiosis-specific
telomere adaptor complex TERB1-TERB2-MAJIN and its evolutionary history.
In the first part of this thesis high-resolution Structured Illumination Microscopy
(SIM), indirect immunofluorescence and Telo-FISH on mouse spermatocytes
were used to determine precisely how the telomere complex proteins are
localized with relation to the shelterin telomeric TRF1 protein and telomeric
DNA. During zygotene and pachytene stages staining patterns revealed
extensively overlapping of meiotic telomere complex proteins distributions in
which TERB2 organization is more heterogeneous than TERB1 and MAJIN at
the chromosome ends. Further, TRF1 localization was shown at the side of
lateral elements (LEs) ends with grasp-like distribution surrounding the TERB1
and MAJIN signals in zygotene and pachytene stages. Interestingly, telomeric
DNA was shown to be laterally distributed and partially overlapping with the
more central distribution displayed by meiotic telomere complex proteins of LEs
ends. The combination of these results allowed to describe an alternative model
of the telomere attachment to the NE during meiotic prophase I. The second part of this thesis, analyses mouse TERB1, TERB2, and MAJIN
evolutionary history. The lack of similarity between mouse and fission yeast
meiotic-specific telomere adaptor proteins has raised the question about the
origin of this specific complex through evolution. To identify mouse TERB1,
TERB2, and MAJIN putative orthologues, computational approaches and
phylogenetic analyses were performed. Besides, to test their potential function
during meiosis, expression studies were conducted. From these analyses, it was
revealed that mouse meiosis-specific telomere complex is ancient, as it
originated as early as eumetazoans pointing to a single origin. The absence of
any homologs in Nematoda and only a few candidates detected in Arthropoda
for meiosis-specific telomere complex, seemed, that these proteins have been
lost/replaced or highly diversified in these lineages. Remarkably, TERB1, TERB2,
and MAJIN protein domains involved in the formation of the complex as well as
those required for the interaction with the telomere shelterin protein and the
LINC complexes revealed high sequence similarity across all clades. Finally,
gene expression in the cnidarian Hydra Vulgaris provided evidence that the
TERB1-TERB2-MAJIN complex is selectively expressed in the germline
suggesting conservation of meiotic functions across metazoan evolution.
In summary, this thesis provides significant insights into the meiosis-specific
telomere complex mechanism to engage telomeres to the nuclear envelope and
the elucidation of its origin in metazoans.
Neuroblastoma is the most abundant, solid, extracranial tumor in early childhood and the leading cause of cancer-related childhood deaths worldwide. Patients with high-risk neuroblastoma often show MYCN-amplification and elevated levels of Aurora-A. They have a low overall survival and despite multimodal therapy options a poor therapeutic prognosis. MYCN-amplified neuroblastoma cells depend on Aurora-A functionality. Aurora-A stabilizes MYCN and prevents it from proteasomal degradation by competing with the E3 ligase SCFFBXW7. Interaction between Aurora-A and MYCN can be observed only in S phase of the cell cycle and activation of Aurora-A can be induced by MYCN in vitro. These findings suggest the existence of a profound interconnection between Aurora-A and MYCN in S phase. Nevertheless, the details remain elusive and were investigated in this study.
Fractionation experiments show that Aurora-A is recruited to chromatin in S phase in a MYCN-dependent manner. Albeit being unphosphorylated on the activating T288 residue, Aurora-A kinase activity was still present in S phase and several putative, novel targets were identified by phosphoproteomic analysis. Particularly, eight phosphosites dependent on MYCN-activated Aurora-A were identified. Additionally, phosphorylation of serine 10 on histone 3 was verified as a target of this complex in S phase. ChIP-sequencing experiments reveal that Aurora-A regulates transcription elongation as well as histone H3.3 variant incorporation in S phase. 4sU-sequencing as well as immunoblotting demonstrated that Aurora-A activity impacts splicing. PLA measurements between the transcription and replication machinery revealed that Aurora-A prevents the formation of transcription-replication conflicts, which activate of kinase ATR.
Aurora-A inhibitors are already used to treat neuroblastoma but display dose-limiting toxicity. To further improve Aurora-A based therapies, we investigated whether low doses of Aurora-A inhibitor combined with ATR inhibitor could increase the efficacy of the treatment albeit reducing toxicity. The study shows that the combination of both drugs leads to a reduction in cell growth as well as an increase in apoptosis in MYCN-amplified neuroblastoma cells, which is not observable in MYCN non-amplified neuroblastoma cells. This new approach was also tested by a collaboration partner in vivo resulting in a decrease in tumor burden, an increase in overall survival and a cure of 25% of TH-MYCN mice. These findings indicate indeed a therapeutic window for targeting MYCN-amplified neuroblastoma.
Die Regulation der Genexpression steht am Anfang vieler zellbiologischer Prozesse wie beispielsweise dem Zellwachstum oder der Differenzierung. Gene werden an Promotoren transkribiert, wobei ein Promotor selbst aus vielen logischen Einheiten aufgebaut ist, den Transkriptionsfaktorbindestellen (TFBSs). Diese können sehr nah beieinander liegen, aber auch weit entfernt voneinander sein. Sie werden spezifisch von Transkriptionsfaktoren (TFs) gebunden, die die Transkritptionsrate z.B. verstärken (Enhancer) oder schwächen (Silencer) können. Zwei oder mehr dieser TFBSs mit bestimmtem Abstand werden als "Module" zusammengefasst, die über Spezies hinweg konserviert sein können. Typischerweise findet man Module in Zellen mit einem Zellkern. Spezies mit gemeinsamen Modulen können ein Hinweis auf die gemeinsame phylogenetische Abstammung darstellen, aber auch gemeinsame Funktionsmechanismen von TFs über Gene hinweg aufdecken. Heutzutage sind verschiedene Anwendungen verfügbar, mit denen nach TFBSs in DNA gesucht werden kann. Zum Zeitpunkt des Verfassens dieser Arbeit sind aber nur zwei kommerzielle Produkte bekannt, die nicht nur TFBSs, sondern auch Module erkennen. Deshalb stellen wir hier die freie und quelloffene Lösung "AIModules" vor, die diese Lücke füllt und einen Webservice zur Verfügung stellt, der es erlaubt nach TFBSs sowie nach Modulen auf DNA- und auf RNA-Abschnitten zu suchen. Für die Motivesuche werden entweder Matrizen aus der Jaspar Datenbank oder Matrizen vom Anwender verwendet. Darüberhinaus zeigen wir, dass unser Tool für die TF Suche nur Sekunden benötigt, wohingegen conTraV3 mindestens eine Stunde für dieselbe Analyse braucht. Zusätzlich kann der Anwender bei unserem Tool den Grad der Konserviertheit für TFs mit angeben und wir zeigen, dass wir mit unserer Lösung, die die Jaspar Datenbank heranzieht, mehr Module finden, als ein kommerziell verfügbares Produkt. Weiterhin kann mit unserer Lösung auch auf RNA-Sequenzen nach regulatorischen Motiven gesucht werden, wenn der Anwender die dafür nötigen Matrizen liefert. Wir zeigen dies am Beispiel von Polyadenylierungsstellen. Zusammenfassend stellen wir ein Werkzeug vor, das erstens frei und quelloffen ist und zweitens entweder auf Servern veröffentlicht werden kann oder On-Site auf einem Notebook läuft. Unser Tool erlaubt es Promotoren zu analysieren und nach konservierten Modulen sowie TFBSs in Genfamilien sowie nach regulatorischen Elementen in mRNA wie z.B. Polyadenylierungsstellen oder andere regulatorische Elemente wie beispielsweise Enhancern oder Silencern in genomischer DNA zu suchen.
Im Zuge der Bemühungen um neue, tumorspezifische Therapieansätze für die Myelomerkrankung hat sich der C-X-C-Chemokinrezeptor 4 (CXCR4) aufgrund seiner zentralen Rolle in der Tumorgenese als vielversprechender Angriffspunkt hervorgetan. Im Sinne eines theranostischen Konzepts wird der Rezeptor mithilfe eines radioaktiv markierten Liganden quantifiziert und anschließend von rezeptorspezifischen Radiotherapeutika als Zielstruktur genutzt. Die CXCR4-Expression ist allerdings ein höchst dynamischer Prozess mit großer inter- und intraindividueller Heterogenität, der u.a. durch eine begleitende Chemotherapie beeinflusst werden kann. Ob sich therapieinduzierte Veränderungen der Rezeptorexpression gezielt nutzen lassen, um die CXCR4-Expression zu optimieren und so die Effektivität der CXCR4-gerichteten Strategien zu steigern, wurde bislang nicht untersucht.
Vor diesem Hintergrund wurden in der vorliegenden Arbeit verschiedene, in der Myelomtherapie etablierte Substanzen sowohl einzeln als auch in Kombination hinsichtlich ihres Einflusses auf die CXCR4-Expression von MM-Zelllinien und primären MM-Zellen unter in vitro Bedingungen analysiert.
In den durchgeführten Experimenten zeigte sich eine hohe Variabilität der CXCR4-Expression der MM-Zellen nach Therapieinduktion, die sich als substanz-, dosis- und zeitabhängig herausstellte. Die Ergebnisse bestätigten das große Potenzial der therapieinduzierten Modulation der CXCR4-Expression. Im weiteren Verlauf sind translationale Forschungsansätze gerechtfertigt, die die Übertragbarkeit der in vitro gewonnenen Ergebnisse auf die komplexen Vorgänge im lebenden Organismus überprüfen. Langfristiges Ziel ist der Entwurf eines patientenzentrierten, multimodalen Therapiekonzepts, welches das CXCR4-gerichtete theranostische Konzept mit einer individuell angepassten, medikamentösen MM-Therapie kombiniert.
Comparing the appetitive learning performance of six European honeybee subspecies in a common apiary
(2021)
The Western honeybee (Apis mellifera L.) is one of the most widespread insects with numerous subspecies in its native range. How far adaptation to local habitats has affected the cognitive skills of the different subspecies is an intriguing question that we investigate in this study. Naturally mated queens of the following five subspecies from different parts of Europe were transferred to Southern Germany: A. m. iberiensis from Portugal, A. m. mellifera from Belgium, A. m. macedonica from Greece, A. m. ligustica from Italy, and A. m. ruttneri from Malta. We also included the local subspecies A. m. carnica in our study. New colonies were built up in a common apiary where the respective queens were introduced. Worker offspring from the different subspecies were compared in classical olfactory learning performance using the proboscis extension response. Prior to conditioning, we measured individual sucrose responsiveness to investigate whether possible differences in learning performances were due to differential responsiveness to the sugar water reward. Most subspecies did not differ in their appetitive learning performance. However, foragers of the Iberian honeybee, A. m. iberiensis, performed significantly more poorly, despite having a similar sucrose responsiveness. We discuss possible causes for the poor performance of the Iberian honeybees, which may have been shaped by adaptation to the local habitat.
Our universe may have started by Qubit decoherence:
In quantum computers, qubits have all their states undefined during calculation and become defined as output (“decoherence”). We study the transition from an uncontrolled, chaotic quantum vacuum (“before”) to a clearly interacting “real world”. In such a cosmology, the Big Bang singularity is replaced by a condensation event of interacting strings. This triggers a crystallization process. This avoids inflation, not fitting current observations: increasing long-range interactions limit growth and crystal symmetries ensure the same laws of nature and basic symmetries over the whole crystal. Tiny mis-arrangements provide nuclei of superclusters and galaxies and crystal structure allows arrangement of dark (halo regions) and normal matter (galaxy nuclei) for galaxy formation. Crystals come and go: an evolutionary cosmology is explored: entropic forces from the quantum soup “outside” of the crystal try to dissolve it. This corresponds to dark energy and leads to a “big rip” in 70 Gigayears. Selection for best growth and condensation events over generations of crystals favors multiple self-organizing processes within the crystal including life or even conscious observers in our universe. Philosophically this theory shows harmony with nature and replaces absurd perspectives of current cosmology.
Independent of cosmology, we suggest that a “real world” (so our everyday macroscopic world) happens only inside a crystal. “Outside” there is wild quantum foam and superposition of all possibilities. In our crystallized world the vacuum no longer boils but is cooled down by the crystallization event, space-time exists and general relativity holds. Vacuum energy becomes 10**20 smaller, exactly as observed in our everyday world. We live in a “solid” state, within a crystal, the n quanta which build our world have all their different m states nicely separated. There are only nm states available for this local “multiverse”. The arrow of entropy for each edge of the crystal forms one fate, one world-line or clear development of our world, while layers of the crystal are different system states. Mathematical leads from loop quantum gravity (LQG) point to required interactions and potentials. Interaction potentials for strings or loop quanta of any dimension allow a solid, decoherent state of quanta challenging to calculate. However, if we introduce here the heuristic that any type of physical interaction of strings corresponds just to a type of calculation, there is already since 1898 the Hurwitz theorem showing that then only 1D, 2D, 4D and 8D (octonions) allow complex or hypercomplex number calculations. No other hypercomplex numbers and hence dimensions or symmetries are possible to allow calculations without yielding divisions by zero. However, the richest solution allowed by the Hurwitz theorem, octonions, is actually the observed symmetry of our universe, E8. Standard physics such as condensation, crystallization and magnetization but also solid-state physics and quantum computing allow us to show an initial mathematical treatment of our new theory by LQG to describe the cosmological state transformations by equations, and, most importantly, point out routes to parametrization of free parameters looking at testable phenomena, experiments and formulas that describe processes of crystallization, protein folding, magnetization, solid-state physics and quantum computing. This is presented here for LQG, for string theory it would be more elegant but was too demanding to be shown here.
Note: While my previous Opus server preprint “A new cosmology of a crystallization process (decoherence) from the surrounding quantum soup provides heuristics to unify general relativity and quantum physics by solid state physics” (https://doi.org/10.25972/OPUS-23076) deals with the same topics and basic formulas, this new version is improved: clearer in title, better introduction, more stringent in its mathematics and improved discussion of the implications including quantum computing, hints for parametrization and connections to LQG and other current cosmological efforts.
This 5th of June 2021 version is again an OPUS preprint, but this will next be edited for Archives https://arxiv.org.
The nuclear envelope serves as important mRNA surveillance system. In yeast and humans, several control mechanisms act in parallel to prevent nuclear export of unprocessed mRNAs. However, trypanosomes lack homologues to most of the proteins involved. In addition, gene expression in trypanosomes relies almost completely on post-transcriptional regulation as they transcribe mRNAs as long polycistrons, which are subsequently processed into individual mRNA molecules by trans-splicing. As trans-splicing is not error-free, unspliced mRNAs may be recognized and prevented from reaching the cytoplasm by a yet unknown mechanism.
When trans-splicing is inhibited in trypanosomes, the formation of a novel RNA granule type at the cytoplasmic periphery of the nucleus, so called nuclear periphery granules (NPGs) was previously observed. To identify potential regulators of nuclear export control, changes in protein localization which occur when trans-splicing is inhibited, were globally analyzed during this work. For this, trypanosome nuclei were purified under conditions maintaining NPG attachment to the nucleus, in the absence and presence of trans-splicing. Mass spectrometry analyses identified 128 proteins which are specifically enriched in nuclear preparations of cells inhibited for trans-splicing. Amongst them are proteins, which change their localization to the nucleus or to the nuclear pores as well as many proteins that move into NPGs. Some of these proteins are promising candidates for nuclear export control proteins, as the changes in localization (to the nucleus or nuclear pores) were specific to the accumulation of unspliced mRNAs. The NPG proteome almost exclusively contains proteins involved in mRNA metabolism, mostly unique to trypanosomes, notably major translation initiation factors were absent. These data indicate that NPGs are RNP complexes which have started or completed nuclear export, but not yet entered translation. As a byproduct of these proteomic studies, a high-quality dataset of the yet unknown T. brucei nuclear proteome is provided, closing an important gap in knowledge to study trypanosome biology, in particular nuclear related processes.
NPGs were characterized in more detail by microscopy. The granules are cytoplasmic and present in at least two different trypanosome life cycle stages. There are at least two distinct granule subsets, with differences in protein composition. A closer analysis of NPGs by electron microscopy revealed that the granules are electron dense structures, which are connected to nuclear pores by string-like structures.
In order to approach the function of NPGs, on the one hand, the hypothesis that NPGs might be related to perinuclear germ granules of adult gonads of C. elegans was tested: we found no relation between the two granule types. On the other hand, initial single molecule mRNA FISH experiments performed in trypanosomes showed no accumulation of unspliced transcripts in NPGs, arguing against an involvement of the granules in mRNA quality control.
ERK1/2 are known key players in the pathophysiology of heart failure, but the members of the ERK cascade, in particular Raf1, can also protect the heart from cell death and ischemic injury. An additional autophosphorylation (ERK1 at Thr208, ERK2 at Thr188) empowers ERK1/2 translocation to the nucleus and phosphorylation of nuclear targets which take part in the development of cardiac hypertrophy. Thereby, targeting this additional phosphorylation is a promising pharmacological approach.
In this thesis, an in silico model of ERK cascade in the cardiomyocyte is introduced. The model is a semi-quantitive model and its behavior was tested with different softwares (SQUAD and CellNetAnalyzer). Different phosphorylation states of ERK1/2 as well as different stimuli can be reproduced. The different types of stimuli include hypertrophic as well as non-hypertrophic stimuli. With the introduced in-silico model time courses and synergistic as well as antagonistic receptor stimuli combinations can be predicted. The simulated time courses were experimentally validated. SQUAD was mainly used to make predictions about time courses and thresholds, whereas CNA was used to analyze steady states and feedback loops.
Furthermore, new targets of ERK1/2 which partially contribute, also in the formation of cardiac hypertrophy, were identified and the most promising of them were illuminated. Important further targets are Caspase 8, GAB2, Mxi-2, SMAD2, FHL2 and SPIN90.
Cardiomyocyte gene expression data sets were analyzed to verify involved components and to find further significantly altered genes after induced hypertrophy with TAC (transverse aortic constriction). Changes in the ultrastructure of the cardiomyocyte are the final result of induced hypertrophy.
Olfactory circuits change structurally and physiologically during development and adult life. This allows insects to respond to olfactory cues in an appropriate and adaptive way according to their physiological and behavioral state, and to adapt to their specific abiotic and biotic natural environment. We highlight here findings on olfactory plasticity and modulation in various model and non-model insects with an emphasis on moths and social Hymenoptera. Different categories of plasticity occur in the olfactory systems of insects. One type relates to the reproductive or feeding state, as well as to adult age. Another type of plasticity is context-dependent and includes influences of the immediate sensory and abiotic environment, but also environmental conditions during postembryonic development, periods of adult behavioral maturation, and short- and long-term sensory experience. Finally, plasticity in olfactory circuits is linked to associative learning and memory formation. The vast majority of the available literature summarized here deals with plasticity in primary and secondary olfactory brain centers, but also peripheral modulation is treated. The described molecular, physiological, and structural neuronal changes occur under the influence of neuromodulators such as biogenic amines, neuropeptides, and hormones, but the mechanisms through which they act are only beginning to be analyzed.
The transcription factor NRF2 is considered as the master regulator of cytoprotective and ROS-detoxifying gene expression. Due to their vulnerability to accumulating reactive oxygen species, melanomas are dependent on an efficient oxidative stress response, but to what extent melanomas rely on NRF2 is only scarcely investigated so far. In tumor entities harboring activating mutations of NRF2, such as lung adenocarcinoma, NRF2 activation is closely connected to therapy resistance. In melanoma, activating mutations are rare and triggers and effectors of NRF2 are less well characterized.
This work revealed that NRF2 is activated by oncogenic signaling, cytokines and pro-oxidant triggers, released cell-autonomously or by the tumor microenvironment. Moreover, silencing of NRF2 significantly reduced melanoma cell proliferation and repressed well-known NRF2 target genes, indicating basal transcriptional activity of NRF2 in melanoma. Transcriptomic analysis showed a large set of deregulated gene sets, besides the well-known antioxidant effectors. NRF2 suppressed the activity of MITF, a marker for the melanocyte lineage, and induced expression of epidermal growth factor receptor (EGFR), thereby stabilizing the dedifferentiated melanoma phenotype and limiting pigmentation markers and melanoma-associated antigens. In general, the dedifferentiated melanoma phenotype is associated with a reduced tumor immunogenicity. Furthermore, stress-inducible cyclooxygenase 2 (COX2) expression, a crucial immune-modulating gene, was regulated by NRF2 in an ATF4-dependent manner. Only in presence of both transcription factors was COX2 robustly induced by H2O2 or TNFα. COX2 catalyzes the first step of the prostaglandin E2 (PGE2) synthesis, which was described to be associated with tumor immune evasion and reduction of the innate immune response.
In accordance with these potentially immune-suppressive features, immunocompetent mice injected with NRF2 knockout melanoma cells had a strikingly longer tumor-free survival compared to NRF2-proficient cells. In line with the in vitro data, NRF2-deficient tumors showed suppression of COX2 and induction of MITF. Furthermore, transcriptomic analyses of available tumors revealed a strong induction of genes belonging to the innate immune response, such as RSAD2 and IFIH1. The expression of these genes strongly correlated with immune evasion parameters in human melanoma datasets and NRF2 activation or PGE2 supplementation limited the innate immune response in vitro.
In summary, the stress dependent NRF2 activation stabilizes the dedifferentiated melanoma phenotype and facilitates the synthesis of PGE2. As a result, NRF2 reduces gene expression of the innate immune response and promotes the generation of an immune-cold tumor microenvironment. Therefore, NRF2 not only elevated the ROS resilience, but also strongly contributed to tumor growth, maintenance, and immune control in cutaneous melanoma.
Background: The chemokine receptor CCR7 is crucial for an intact immune function, but its expression is also associated with clinical outcome in several malignancies. No data exist on the expression of CCR7 in adrenocortical tumors. Methods: CCR7 expression was investigated by qRT-PCR and immunohistochemistry in 4 normal adrenal glands, 59 adrenocortical adenomas, and 181 adrenocortical carcinoma (ACC) samples. Results: CCR7 is highly expressed in the outer adrenocortical zones and medulla. Aldosterone-producing adenomas showed lower CCR7 protein levels (H-score 1.3 ± 1.0) compared to non-functioning (2.4 ± 0.5) and cortisol-producing adenomas (2.3 ± 0.6), whereas protein expression was variable in ACC (1.8 ± 0.8). In ACC, CCR7 protein expression was significantly higher in lymph node metastases (2.5 ± 0.5) compared to primary tumors (1.8±0.8) or distant metastases (2.0 ± 0.4; p < 0.01). mRNA levels of CCR7 were not significantly different between ACCs, normal adrenals, and adrenocortical adenomas. In contrast to other tumor entities, neither CCR7 protein nor mRNA expression significantly impacted patients' survival. Conclusion: We show that CCR7 is expressed on mRNA and protein level across normal adrenals, benign adrenocortical tumors, as well as ACCs. Given that CCR7 did not influence survival in ACC, it is probably not involved in tumor progression, but it could play a role in adrenocortical homeostasis.
The unusual occurrence and developmental diversity of asexual eukaryotes remain a puzzle. De novo formation of a functioning asexual genome requires a unique assembly of sets of genes or gene states to disrupt cellular mechanisms of meiosis and gametogenesis, and to affect discrete components of sexuality and produce clonal or hemiclonal offspring. We highlight two usually overlooked but essential conditions to understand the molecular nature of clonal organisms, that is, a nonrecombinant genomic assemblage retaining modifiers of the sexual program, and a complementation between altered reproductive components. These subtle conditions are the basis for physiologically viable and genetically balanced transitions between generations. Genomic and developmental evidence from asexual animals and plants indicates the lack of complementation of molecular changes in the sexual reproductive program is likely the main cause of asexuals' rarity, and can provide an explanatory frame for the developmental diversity and lability of developmental patterns in some asexuals as well as for the discordant time to extinction estimations.