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Villa, F.

Publications and source records attributed to Villa, F..

2 recordsLinked to original sources

Image Scanning Microscopy with Single-Photon Detector Array

Image scanning microscopy (ISM) improves the spatial resolution of conventional confocal laser-scanning microscopy (CLSM), but current implementations reduce versatility and restrict its combination with fluorescence spectroscopy techniques, such as fluorescence lifetime. Here, we describe a natural design of ISM based on a fast single-photon detector array, which allows straightforward upgrade of an existing confocal microscope, without compromising any of its functionalities. In contrast to all-optical ISM implementations, our approach provides access to the raw scanned images, opening the way to adaptive reconstruction methods, capable of considering different imaging conditions and distortions. We demonstrate its utility in the context of fluorescence lifetime, deep, multicolor and live-cell imaging. This implementation will pave the way for a transparent and massive transition from conventional CLSM to ISM.\n\nconfocal microscopy | time-resolved spectroscopy | image scanning microscopy | single-photon detector array

bioengineering

Conformational Dynamics In TRPV1 Channels Reported By An Encoded Coumarin Amino Acid

Transient Receptor Potential Vanilloid (TRPV1) channels support the detection and integration of nociceptive input. Currently available functional and structural data suggest that that TRPV1 channels have two potential gates within their cation selective permeation pathway: a barrier formed by a bundle crossing at the intracellular entrance and a second constriction created by the ion selectivity filter. To describe conformational changes associated with channel gating within the pore, the fluorescent non-canonical amino acid (f- ncAA) coumarin-tyrosine was genetically encoded at Y671, a residue proximal to the selectivity filter. TRPV1 channels expressing coumarin at either site displayed normal voltage- and agonist-dependent gating. Next, total internal reflection microscopy (TIRF) was performed to enable ultra-rapid, millisecond imaging of the conformational dynamics in single TRPV1 channels in live cells. Here, the data obtained from channels expressed in human derived cells show that optical fluctuations, photon counts, and variance of noise analysis from Y671 coumarin encoded in TRPV1 tetramers correlates closely with channel activation by capsaicin, thus providing an direct optical marker of channel activation at the selectivity filter. In companion molecular dynamics simulations, Y671 displays alternating solvent exposure between the closed and open states, giving support to the optical data. These calculations further suggest a direct involvement of Y671 in controlling the relative position of the pore helix and its role in supporting ionic conductance at the TRPV1 selectivity filter.

biophysics