Actomyosin-based contractility acts on cadherin junctions to support tissue integrity and morphogenesis. The actomyosin apparatus of the epithelial zonula adherens (ZA) is built by coordinating ...junctional actin assembly with Myosin II activation. However, the physical interaction between Myosin and actin filaments that is necessary for contractility can induce actin filament turnover, potentially compromising the contractile apparatus itself.
We now identify tension-sensitive actin assembly as one cellular solution to this design paradox. We show that junctional actin assembly is maintained by contractility in established junctions and increases when contractility is stimulated. The underlying mechanism entails the tension-sensitive recruitment of vinculin to the ZA. Vinculin, in turn, directly recruits Mena/VASP proteins to support junctional actin assembly. By combining strategies that uncouple Mena/VASP from vinculin or ectopically target Mena/VASP to junctions, we show that tension-sensitive actin assembly is necessary for junctional integrity and effective contractility at the ZA.
We conclude that tension-sensitive regulation of actin assembly represents a mechanism for epithelial cells to resolve potential design contradictions that are inherent in the way that the junctional actomyosin system is assembled. This emphasizes that maintenance and regulation of the actin scaffolds themselves influence how cells generate contractile tension.
Display omitted
•Contractile tension stimulates actin assembly at the epithelial zonula adherens•Vinculin mediates tension-sensitive actin assembly through Mena/VASP proteins•Tension recruits vinculin to promote junctional actin assembly•Tension-sensitive actin assembly is necessary for junctional contractility
Leerberg et al. demonstrate that actin assembly at the epithelial zonula adherens responds to contractile tension. Contractility recruits vinculin to apical junctions, where it promotes actin assembly via Mena/VASP proteins. This homeostatic pathway counteracts stress-induced actin filament turnover to preserve effective junctional contractility.
From the last couple of decades, lyotropic liquid crystals have garnered enormous attentions in medical and pharmaceutical sciences. Non-toxic, chemically stable, and biocompatible properties of ...these liquid crystal systems are contributing to their applications for drug delivery. Among a large variety of liquid crystal phases, inverse bicontinuous cubic and inverse hexagonal mesophases have been extensively investigated for their ability to encapsulate and controlled release of bioactive molecules of various sizes and polarity. The concept of changing the drug release rate in situ by simply changing the mesophase structure is much more fascinating. The encapsulation of bioactive compounds in mesophase systems of desirable features in sub-micron sized particles such as hexosomes and cubosomes, at ambient and high temperature is bringing innovation in the development of new drug applications. This review article outlines unique structural features of cubosomes and hexosomes, their methods of productions, factors affecting their formations and their potential utilization as smart nano-carriers for biopharmaceuticals in drug delivery applications.
Model representation of inverse hexagonal (HII) and inverse bicontinuous cubic (QIID) liquid crystalline phases. Display omitted
Direct electrochemical templating is carried out using a thin layer of a self‐assembled diamond phase (QIID) of phytantriol to create a platinum film with a novel nanostructure. Small‐angle X‐ray ...scattering shows that the nanostructured platinum films are asymmetrically templated and exhibit “single diamond” morphology with Fd3m symmetry.
Here, we report a systematic investigation of the effect of experimental parameters on the structure, morphology and electrochemically active surface area of 3-D mesoporous platinum (Pt) framework. ...Template-assisted deposition of the mesoporous Pt framework is achieved using phytantriol-based inverse bicontinuous cubic phase of double diamond morphology (
Q
II
D
) with Pn3m symmetry. Platinum is deposited electrochemically using hexachloroplatinic acid solution present within the aqueous domains of the cubic phase template. Deposition conditions, particularly the deposition potentials, are shown to significantly affect the surface morphology, porosity and electrochemically active surface area of the deposited Pt framework. Furthermore, the effect of underlying substrate on the structure and morphology of the mesoporous Pt framework is also investigated.
There is little research evidence to explain why older adults have more problems adapting to new spectacles incorporating astigmatic changes than younger adults. We tested the hypothesis that ...astigmatic lenses oriented obliquely would lead to errors in verticality perception that are greater for older than younger adults.
Participants included 12 young (mean ± SD age 25.1 ± 5.0 years) and 12 older (70.2 ± 6.3 years) adults with normal vision. Verticality perception was assessed using a computer-based subjective visual vertical (SVV) task, under static and dynamic (in the presence of a moving peripheral distractor) conditions and when viewing targets through the near refractive correction (control condition), and two forms of astigmatic lenses oriented in the vertical, horizontal, and oblique meridians.
The older group demonstrated much greater dynamic SVV errors (e.g., 3.4° for the control condition) than the younger group (1.2°, P = 0.002), larger errors with vertical and horizontal astigmatic lenses (older group 4.1°and 5.2° for toric and magnifier lenses vs. younger group 1.2° and 1.4°, respectively, P < 0.001), and a larger influence of the oblique astigmatic lenses (older group 5.6° vs. younger group 2.1°, P<0.001).
Astigmatic lenses produced little or no errors in SVV in young adults, but large static and dynamic SVV errors in older adults. This indicates a greater reliance on visual input with increased age for SVV, and helps explain why oblique astigmatic refractive corrections can cause dizziness in older patients and why they report greater difficulties adapting to new spectacles with astigmatic changes.
Platinum and platinum-based materials with high catalytic performance, and chemical and mechanical stability are vital to electronic devices, biomedical science, optics, petroleum, and automotive ...industries. Because of the limited supply and high cost of platinum, it is highly desirable to develop new effective methodologies which can decrease the platinum loading by increasing its electrocatalytic properties. Depending upon their size, shape, and morphology, platinum materials have shown significant improvement in the surface catalysed chemical transformation pathways in fuel cell technology. Much research is now focused on the manufacturing and engineering of platinum and platinum-based materials which proffer enhanced catalytic efficiency, and offer chemical and mechanical robustness.
PDF
