The extracellular matrix (ECM) plays crucial roles in animal development and diseases. Here, we report that Wnt/β-catenin signaling induces the ECM remodeling during Hydra axis formation. We ...determined the micro- and nanoscopic arrangement of fibrillar type I collagen along Hydra’s body axis using high-resolution microscopy and X-ray scattering. Elasticity mapping of the ECM ex vivo revealed distinctive elasticity patterns along the body axis. A proteomic analysis of the ECM showed that these elasticity patterns correlate with a gradient-like distribution of metalloproteases along the body axis. Activation of the Wnt/β-catenin pathway in wild-type and transgenic animals alters these patterns toward low ECM elasticity patterns. This suggests a mechanism whereby high protease activity under control of Wnt/β-catenin signaling causes remodeling and softening of the ECM. This Wnt-dependent spatiotemporal coordination of biochemical and biomechanical cues in ECM formation was likely a central evolutionary innovation for animal tissue morphogenesis.
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•Hierarchical structural order of Hydra ECM correlates with tissue morphogenesis•Elasticity patterns and structural order are tightly connected to tissue patterning•Gradients of matrix protease govern elasticity patterns of Hydra ECM•Wnt/β-catenin signaling acts on Hydra ECM structural order and elasticity
Histology; Microscopic anatomy; Zoology; Molecular biology
•The Co–Nb and Al–Nb were updated to get a reasonable description of Co–Al–Nb system.•A consistent thermodynamic description of Co–Al–Nb system is obtained basing on rich experimental data.•Alkemade ...theorem could not decide the saddle point of two congruently melting phase.
The Co–Al–Nb ternary system and its two binary subsystems Co–Nb and Al–Nb were thermodynamically modeled by the Calphad method based on own experimental results and critically assessed literature data. A characteristic of the Co–Nb and Co–Al–Nb system is the coexistence of three polytypes of Laves phases: hexagonal C14 and C36 as well as cubic C15. Two-sublattice models were used for the three Laves phases to enable a realistic description of their homogeneity ranges in the Co–Nb and Co–Al–Nb system. A re-assessment was needed for the Al–Nb system to obtain a better description of the homogeneity range of Nb2Al and the liquidus projection of the Co–Al–Nb system. The comparison between calculated and experimental values shows that the optimized set of thermodynamic parameters gives a very good description of most of the experimental data resulting in a complete, consistent thermodynamic description of the three systems Co–Nb, Al–Nb and Co–Al–Nb.
High-melting Nb-based alloys hold significant promise for the development of novel high-temperature materials for structural applications. In order to understand the effect of alloying elements Al ...and Fe, the Nb-rich part of the ternary Nb-Al-Fe system was investigated. A series of Nb-rich ternary alloys were synthesized from high-purity Nb, Al, and Fe metals by arc melting. Solidification paths were identified and the liquidus surface of the Nb corner of the ternary system was established by analysis of the as-melted microstructures and thermal analysis. Complementary analysis of heat-treated samples yielded isothermal sections at 1723 K and 1873 K (1450 °C and 1600 °C).
Alloys based on titanium aluminides received a lot of attention because of their capability to substitute Ni‐based superalloys in high‐temperature applications. However, the phase equilibria between ...the main microstructure constituents (αTi), (βTi), γ (TiAl) and α2 (Ti3Al) can be shifted significantly by impurities such as oxygen especially at high temperatures. This behavior is investigated on the tie‐triangle (αTi) + (βTi) + γ (TiAl) in the ternary Ti‐Al‐Nb system at 1300 °C. An explanation for this behavior could be the occupation of octahedral voids by impurities in certain phases.
Regarding the effect of composition on the mechanical properties of intermetallic phases such as Laves phases, there is conflicting information in the literature. Some authors observed defect ...hardening when deviating from stoichiometric Laves phase composition, whereas others find defect softening. Here, we present a systematic investigation of the defect state, hardness, and elastic modulus of cubic and hexagonal NbCo
2
Laves phases as a function of crystal structure and composition. For this purpose, diffusion couples were prepared which exhibit diffusion layers of the cubic C15 and hexagonal C14 and C36 NbCo
2
Laves phases, with concentration gradients covering their entire homogeneity ranges from 24 to 37 at.% Nb. Direct observations of dislocations and stacking faults in the diffusion layers as a function of composition were performed by electron channeling contrast imaging, and the hardness and elastic modulus were probed in the diffusion layers along the concentration gradients by nanoindentation.
Increasing antibiotic resistance urges for new technologies for studying microbes and antimicrobial mechanism of action. We adapted thermal proteome profiling (TPP) to probe the thermostability of ...Escherichia coli proteins in vivo. E. coli had a more thermostable proteome than human cells, with protein thermostability depending on subcellular location—forming a high‐to‐low gradient from the cell surface to the cytoplasm. While subunits of protein complexes residing in one compartment melted similarly, protein complexes spanning compartments often had their subunits melting in a location‐wise manner. Monitoring the E. coli meltome and proteome at different growth phases captured changes in metabolism. Cells lacking TolC, a component of multiple efflux pumps, exhibited major physiological changes, including differential thermostability and levels of its interaction partners, signaling cascades, and periplasmic quality control. Finally, we combined in vitro and in vivo TPP to identify targets of known antimicrobial drugs and to map their downstream effects. In conclusion, we demonstrate that TPP can be used in bacteria to probe protein complex architecture, metabolic pathways, and intracellular drug target engagement.
Synopsis
Thermal proteome profiling is adapted to Escherichia coli to probe the thermostability of proteins in vivo, yielding insights into protein complex architecture, protein activity, cellular metabolic state, intracellular drug target engagement and drug downstream effects.
The E. coli proteome is more thermostable than the human one, with protein thermostability depending on protein subcellular location.
Subunits of protein complexes residing in one compartment melt similarly, while protein complexes spanning compartments often have their subunits melting in a location‐wise manner.
Knockout of tolC led to the thermal destabilization of its interaction partners, the downregulation of a major porin (OmpF), and increased periplasmic stress.
Thermal proteome profiling is adapted to Escherichia coli to probe the thermostability of proteins in vivo, yielding insights into protein complex architecture, protein activity, cellular metabolic state, intracellular drug target engagement and drug downstream effects.
The Co–Ti system is one of the important systems for the development of Co-based superalloys and it is the only binary Co-X system where the characteristic, fine-scaled γ/γ′ microstructures (fcc-Co ...with fcc L12-ordered TiCo3) can form. Surprisingly, the phase relations and invariant reaction temperatures in the Co-rich part of the system are not very well established and there are fundamental inconsistencies between different versions of the phase diagram. Crucial points such as the type of formation reaction of the γ′ phase TiCo3 from the melt are unclear. The system is not only of high scientific interest because of the presence of the γ/γ’ microstructure, but also due to the occurrence of two different, stable polytypes of the Laves phase TiCo2 (hexagonal C36 and cubic C15 type). The phase fields of these two polytypes should be separated by a two-phase field the existence of which however has never been clearly proven. A re-investigation of the Co-rich part of the phase diagram (0–50 at.% Ti) including all invariant reactions as well as the liquidus, solidus, and solvus lines was performed by not only making use of equilibrated alloys but also applying diffusion couples.
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•No two-phase field was found between the C15 and C36 Laves phase fields possibly due to a coherent equilibrium.•The invariant reaction between L12-type TiCo3 (γ′) and the fcc Co solid solution is of eutectic nature.•The congruent melting temperature of B2 TiCo is above 1500 °C, which solves some controversy existing in the literature.•A revised version of the Co-rich part of the Co–Ti phase diagram is constructed.
We report on the sub-nanometer scale characterization of Co-12Ti-4Mo and Co-12Ti-4Cr (at.%) model alloys. Atom probe tomography reveals that Co and Cr partition to γ, whereas Ti and Mo to γ′. ...Additions of Mo and Cr to the reference Co-12Ti system lead to strong increases in γ′ volume fraction by about 25% and 12%, respectively. Element-specific spatial distribution maps along the 001 direction of the L12-ordered γ′ phase reveal that both Mo and Cr preferentially replace Ti on its sublattice. The remaining excess Ti is available for formation of additional γ′, resulting in enhanced γ′ volume fractions.
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Lysosomes are catabolic organelles involved in macromolecular digestion, and their dysfunction is associated with pathologies ranging from lysosomal storage disorders to common neurodegenerative ...diseases, many of which have lipid accumulation phenotypes. The mechanism of lipid efflux from lysosomes is well understood for cholesterol, while the export of other lipids, particularly sphingosine, is less well studied. To overcome this knowledge gap, we have developed functionalized sphingosine and cholesterol probes that allow us to follow their metabolism, protein interactions, and their subcellular localization. These probes feature a modified cage group for lysosomal targeting and controlled release of the active lipids with high temporal precision. An additional photocrosslinkable group allowed for the discovery of lysosomal interactors for both sphingosine and cholesterol. In this way, we found that two lysosomal cholesterol transporters, NPC1 and to a lesser extent LIMP-2/SCARB2, bind to sphingosine and showed that their absence leads to lysosomal sphingosine accumulation which hints at a sphingosine transport role of both proteins. Furthermore, artificial elevation of lysosomal sphingosine levels impaired cholesterol efflux, consistent with sphingosine and cholesterol sharing a common export mechanism.
Abstract
The RNA binding protein Hfq has a central role in the post-transcription control of gene expression in many bacteria. Numerous studies have mapped the transcriptome-wide Hfq-mediated RNA–RNA ...interactions in growing bacteria or bacteria that have entered short-term growth-arrest. To what extent post-transcriptional regulation underpins gene expression in growth-arrested bacteria remains unknown. Here, we used nitrogen (N) starvation as a model to study the Hfq-mediated RNA interactome as Escherichia coli enter, experience, and exit long-term growth arrest. We observe that the Hfq-mediated RNA interactome undergoes extensive changes during N starvation, with the conserved SdsR sRNA making the most interactions with different mRNA targets exclusively in long-term N-starved E. coli. Taking a proteomics approach, we reveal that in growth-arrested cells SdsR influences gene expression far beyond its direct mRNA targets. We demonstrate that the absence of SdsR significantly compromises the ability of the mutant bacteria to recover growth competitively from the long-term N-starved state and uncover a conserved post-transcriptional regulatory axis which underpins this process.
Graphical Abstract
Graphical Abstract
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