Biology subjects

Allgeyer, E. S.

Publications and source records attributed to Allgeyer, E. S..

6 recordsLinked to original sources

bioRxiv2025

Implementation of an adaptive-optics assisted isoSTED nanoscope

The highest level of three-dimensional (3D) resolution in stimulated emission depletion (STED) nanoscopy involves harnessing a 4Pi architecture using two opposing objectives. This protocol describes the construction and alignment of a 4Pi-STED nanoscope, commonly referred to as an isoSTED nanoscope. It guides interested researchers through assembling optomechanical components, configuring electronic and control devices, aligning the optical beam path, and assessing the instruments performance. Designed for adept optical instrument builders, this protocol offers a detailed roadmap for constructing an isoSTED nanoscope with adaptive optics (AO) in approximately 12 months. With this finely calibrated instrument, researchers can achieve 3D biological images with isotropic sub-50-nm resolution in thick samples up to 35 {micro}m in depth.

bioengineering↗

bioRxiv2024

User-friendly Oblique Plane Microscopy on a fully functional commercially available microscope base

In this work we present an Oblique Plane Microscope designed to work seamlessly with a commercially available microscope base. To support all the functionality offered by the microscope base, where the position of the objective lens is not fixed, we adopted a two-mirror scanning geometry that can compensate for changes to the position of the objective lens during routine microscope operation. We showed that within the expected displacement range of the 100X, 1.35 NA objective lens away from its designed position, and for most practical applications, there is no significant effect on the resolving power, or the fidelity of the 3D data produced by the microscope. Compared to the more traditional scan-lens/galvo-mirror combination, the two-mirror scanning geometry offers higher light-efficiency and a more compact footprint, which could be beneficial to all OPM designs regardless of the use of a commercial base or not.

biophysics↗

bioRxiv2023

Filopodial protrusion driven by density-dependent Ena-TOCA-1 interactions

Filopodia are narrow actin-rich protrusions with important roles in neuronal development. The neuronally-enriched TOCA-1/CIP4 family of F-BAR and SH3 domain adaptor proteins have emerged as upstream regulators that link membrane interactions to actin binding proteins in lamellipodia and filopodia, including WAVE and N-WASP nucleation promoting factors and formins. Here, we demonstrate a direct interaction between TOCA-1 and Ena/VASP actin filament elongators that is mediated by clustered SH3 domain interactions. Using Xenopus retinal ganglion cell axonal growth cones, where Ena/VASP proteins have a native role in filopodia extension, we show that TOCA-1 localises to filopodia and lamellipodia, with a retrograde flow of puncta, and correlates with filopodial protrusion. Two-colour single molecule localization microscopy of TOCA-1 and Ena supports their nanoscale association. TOCA-1 clusters coalesce at advancing lamellipodia and filopodia and operate synergistically with Ena to promote filopodial protrusion dependent on a functional SH3 domain. In analogous yet distinct ways to lamellipodin and IRSp53, we propose that transient TOCA-1 clusters recruit and promote Ena activity to orchestrate filopodial protrusion.

cell biology↗

bioRxiv2021

A method for single molecule localization microscopy of tissues reveals nonrandom distribution of nuclear pores in Drosophila

Single Molecule Localisation Microscopy (SMLM) can provide nanoscale resolution in thin samples but has rarely been applied to tissues, because of high background from out of focus emitters. Here we describe a line scanning microscope that provides optical sectioning for SMLM in tissues. Imaging endogenously-tagged nucleoporins and F-actin on this system using DNA- and peptide-PAINT routinely gives 30nm resolution or better at depths greater than 20 {micro}m. This revealed that the nuclear pores are nonrandomly distributed in most Drosophila tissues, in contrast to cultured cells. Lamin Dm0 shows a complementary localisation to the nuclear pores, suggesting that it corrals the pores. Furthermore, ectopic expression of the tissue-specific Lamin C distributes the nuclear pores more randomly, whereas lamin C mutants enhance nuclear pore clustering, particularly in muscle nuclei. Since nucleoporins interact with specific chromatin domains, nuclear pore clustering could regulate chromatin organisation locally and contribute to the disease phenotypes caused by human Lamin A/C laminopathies.

cell biology↗

bioRxiv2020

3D Adaptive Optical Nanoscopy for Thick Specimen Imaging at sub-50 nm Resolution

Understanding cellular organization demands the best possible spatial resolution in all three dimensions (3D). In fluorescence microscopy, this is achieved by 4Pi nanoscopy methods that combine the concepts of using two opposing objectives for optimal diffraction-limited 3D resolution with switching fluorescent molecules between bright and dark states to break the diffraction limit. However, optical aberrations have limited these nanoscopes to thin samples and prevented their application in thick specimens. Here, we have developed a nanoscope that, by utilizing an advanced adaptive optics strategy, achieves sub-50 nm isotropic resolution of structures such as neuronal synapses and ring canals previously inaccessible in tissue.

biophysics↗

bioRxiv2019

3D super-resolution deep-tissue imaging in living mice

Stimulated emission depletion (STED) microscopy enables the three-dimensional (3D) visualization of dynamic nanoscale structures in living cells, offering unique insights into their organization. However, 3D-STED imaging deep inside biological tissue is obstructed by optical aberrations and light scattering. We present a STED system that overcomes these challenges. Through the combination of 2-photon excitation, adaptive optics, far-red emitting organic dyes, and a long-working distance water-immersion objective lens, our system achieves aberration-corrected 3D super-resolution imaging, which we demonstrate 164 {micro}m deep in fixed mouse brain tissue and 76 {micro}m deep in the brain of a living mouse.

biophysics↗