fluorescence-biomembrane-force-probe-concurrent-quantitation-receptor

Fluorescence Biomembrane Force Probe: Concurrent Quantitation of Receptor-ligand Kinetics and Binding-induced Intracellular Signaling on a Single Cell

Membrane receptor-ligand interactions mediate many cellular functions. Binding kinetics and downstream signaling triggered by these molecular interactions ...

Chinese Academy of Sciences

University of Chinese Academy of Sciences

We have previously shown that the protein kinase A (PKA) inhibitor, 8-chloroadenosine-3',5'-monophosphorothioate (Rp-8-Cl-cAMPS), abolishes ocular dominance plasticity in the cat visual cortex. Here we investigate the effect of this inhibitor on orientation selectivity. The inhibitor reduces orientation selectivity in monocularly deprived animals but not in normal animals. In other words, PKA inhibitors by themselves do not affect orientation selectivity, nor does monocular deprivation by itself, but monocular deprivation in combination with a PKA inhibitor does affect orientation selectivity. This result is found for the receptive fields in both deprived and nondeprived eyes. Although there is a tendency for the orientation selectivity in the nondeprived eye to be higher than the orientation selectivity in the deprived eye, the orientation selectivity in both eyes is considerably less than normal. The result is striking in animals at 4 wk of age. The effect of the monocular deprivation on orientation selectivity is reduced at 6 wk of age and absent at 9 wk of age, while the effect on ocular dominance shifts is less changed in agreement with previous results showing that the critical period for orientation/direction selectivity ends earlier than the critical period for ocular dominance. We conclude that closure of one eye in combination with inhibition of PKA reduces orientation selectivity during the period that orientation selectivity is still mutable and that the reduction in orientation selectivity is transferred to the nondeprived eye.

Orientation selectivity is reduced by monocular deprivation in combination with PKA inhibitors.

A graphite-reduced graphite oxide (rGO) core-sheath structured fiber was synthesized through chemical exfoliation of graphitic carbon fiber. The graphitic carbon fiber was oxidized to form a graphite-graphite oxide core-sheath fiber and followed by thermal exfoliation to form a graphite-rGO core-sheath fiber. The core-sheath fiber with a three-dimensionally (3D) structured rGO sheath possesses a high surface area and pore size around 5.5 nm. A two-electrode supercapacitor constructed with this core-sheath fiber-based paper exhibited a high specific capacitance (140 F g(-1) at a current density of 1 A g(-1)), high power density of 45 kW/kg, and good cycling stability (10% capacity loss after 3000 cycles). The surface area normalized capacitance reached as high as 59.4 μF cm(-2), indicating the effective use of surface area. The low equivalent series resistance value of 0.45 ohm in the Nyquist plot indicates an extremely small resistance between the graphite core and rGO sheet sheath. The hierarchical three-dimensional structure enables one to maximize the advantages of both graphite and rGO sheets. The 3D-structured rGO sheets sheath with regular pore structure is favorable for ion diffusion due to its interconnected porous system, while the graphite core provides an electron transport pathway with high conductivity.

Facile synthesis of graphite-reduced graphite oxide core-sheath fiber via direct exfoliation of carbon fiber for supercapacitor application.

Talin is an integrin-binding protein located at focal adhesion site and serves as both an adapter and a force transmitter. Its integrin binding activity is regulated by the intramolecular autoinhibition interaction between its F3 and RS domains. Here, we used atomic force microscopy to measure the strength of talin autoinhibition complex. Our results suggest that the lifetime of talin autoinhibition complex shows weak catch bond behavior and does not change significantly at smaller forces, while it drops rapidly at larger forces (>10 pN). Moreover, besides the complex conformation revealed by crystal structure, our molecular dynamics (MD) simulations indicate the possible existence of another stable conformation. Further analysis indicates that forces may regulate the equilibrium of the two stable binding states and result in the non-exponential force dependence of the binding lifetime. Our findings reveal a negative regulation mechanism on talin activation and provide a new point of view on the function of talin in focal adhesion.

Article	Year
Orientation selectivity is reduced by monocular deprivation in combination with PKA inhibitors. Journal of neurophysiology\| PubMed ID: 12364519	2002
Facile synthesis of graphite-reduced graphite oxide core-sheath fiber via direct exfoliation of carbon fiber for supercapacitor application. ACS applied materials & interfaces\| PubMed ID: 24820530	2014
The conformational states of talin autoinhibition complex and its activation under forces. Science China. Life sciences\| PubMed ID: 26032591	2015

Qinghua Ji

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