Coupling dynamics of 2D Notch-Delta signalling

Understanding pattern formation driven by cell–cell interactions has been a significant theme in cellular biology for many years. In particular, due to their implications within many biological contexts, lateral-inhibition mechanisms present in the Notch-Delta signalling pathway led to an extensive discussion between biologists and mathematicians. Deterministic and stochastic models have been developed as a consequence of this discussion, some of which address long-range signalling by considering cell protrusions reaching non-neighbouring cells. The dynamics of such signalling systems reveal intricate properties of the coupling terms involved in these models. In this work, we investigate the advantages and drawbacks of a single-parameter long-range signalling model across diverse scenarios. By employing linear and multi-scale analyses, we discover that pattern selection is not only partially explained but also depends on nonlinear effects that extend beyond the scope of these analytical techniques

Ionenleitende Borat- und Silikatglasschichten:Strukturelle und Elektrische Charakterisierung mit Hilfe von TEM und Impedanzspektroskopie

Die strukturellen und elektrischen Eigenschaften sputterdeponierter ionenleitender Borat- und Silikatgläser mit einer Dicke zwischen 10 und 1000 nm werden mit Hilfe von Transmissionselektronenmikroskopie und Impedanzspektroskopie experimentell charakterisiert. Dabei bestätigen sich die amorphe Struktur der Schichten und ihre stöchiometrische Übereinstimmung mit dem Targetmaterial; Ihre spezifische Ionenleitfähigkeit liegt jedoch bis zu zwei Zehnerpotenzen oberhalb der Leitfähigkeit des entsprechenden Massivglases, was auf eine Änderung der Bindungsverhältnisse der Glasmatrix durch den Sputterprozess zurückgeführt wird. Weiterhin beobachtet man, dass die spezifische Leitfähigkeit der Glasschichten unterhalb einer Dicke von 100 nm um bis zu drei Zehnerpotenzen ansteigt. Numerische Computersimulationen auf Basis der Perkolationstheorie zeigen daraufhin, dass dieser Leitfähigkeitsanstieg durch eine räumlich inhomogene Leitfähigkeitsverteilung quantitativ erklärt werden kann

Making Muscle Elastic: The Structural Basis of Myomesin Stretching

The muscle M-band protein myomesin comprises a 36-nm long filament made of repetitive immunoglobulin–helix modules that can stretch to 2.5-fold this length, demonstrating substantial molecular elasticity

Appetite Enhancement and Weight Gain by Peripheral Administration of TrkB Agonists in Non-Human Primates

Loss of function mutations in the receptor tyrosine kinase TrkB pathway resulted in hyperphagia and morbid obesity in human and rodents. Conversely, peripheral or central stimulation of TrkB by its natural ligands BDNF or NT4 reduced body weight and food intake in mice, supporting the idea that TrkB is a key anorexigenic signal downstream of the melanocortin-4 receptor (Mc4r) system. Here we show that in non-human primates TrkB agonists were anorexigenic when applied centrally, but surprisingly orexigenic, leading to gain in appetite, body weight, fat deposits and serum leptin levels, when given peripherally. The orexigenic and pro-obesity effects of peripherally administered TrkB agonists appear to be dose dependent, not associated with fluid retention nor with evidence of receptor down regulation. Our findings revealed that TrkB signaling exerts dual control on energy homeostasis in the primates that could be targeted for the treatment of either wasting disorders or obesity

Organic Nitrate Contribution to New Particle Formation and Growth in Secondary Organic Aerosols from α-Pinene Ozonolysis.

The chemical kinetics of organic nitrate production during new particle formation and growth of secondary organic aerosols (SOA) were investigated using the short-lived radioactive tracer (13)N in flow-reactor studies of α-pinene oxidation with ozone. Direct and quantitative measurements of the nitrogen content indicate that organic nitrates accounted for ∼40% of SOA mass during initial particle formation, decreasing to ∼15% upon particle growth to the accumulation-mode size range (>100 nm). Experiments with OH scavengers and kinetic model results suggest that organic peroxy radicals formed by α-pinene reacting with secondary OH from ozonolysis are key intermediates in the organic nitrate formation process. The direct reaction of α-pinene with NO3 was found to be less important for particle-phase organic nitrate formation. The nitrogen content of SOA particles decreased slightly upon increase of relative humidity up to 80%. The experiments show a tight correlation between organic nitrate content and SOA particle-number concentrations, implying that the condensing organic nitrates are among the extremely low volatility organic compounds (ELVOC) that may play an important role in the nucleation and growth of atmospheric nanoparticles