Biology subjects

Horvath, A. N.

Publications and source records attributed to Horvath, A. N..

3 recordsLinked to original sources

bioRxiv2020

Time-controlled Multichannel Dynamic Traction Imaging of Biaxially Stretched Adherent Cells

Here, a dynamic traction force microscopy method is described which enables sub-second temporal resolution imaging of transient subcellular events secondary to extrinsic stretch of adherent single cells. The system employs a novel tracking approach with minimal computational overhead to compensate substrate-based stretch-induced motion/drift of stretched single cells in real time, allowing capture of biophysical phenomena on multiple channels by fluorescent multichannel imaging on a single camera, thus avoiding the need for beam splitting with associated loss of light. The potential impact of the technique is demonstrated by characterizing transient subcellular forces and corresponding nuclear deformations in equibiaxial stretching experiments, uncovering a high frequency strain-rate dependent response in the transfer of substrate strains to the nucleus.

cell biology↗

bioRxiv2019

The Protein Mat(ters) - Revealing Biologically Relevant Mechanical Contribution of Collagen and Fibronectin Coated Micropatterns

Understanding cell-material interactions requires accurate characterization of substrate mechanics, which are generally measured by indentation-type atomic force microscopy. Although model extracellular matrix coatings are used to facilitate cell-substrate adhesion, their tensile mechanical properties are generally unknown. In this study a novel tensile mechanical characterization of collagen and fibronectin micropatterned polyacrylamide hydrogels is performed. Our findings reveal that the protein coating itself has measurable and biologically relevant consequences, with ligand-specific tensile resistance of the patterned regions relative to the non-patterned surfaces. To our knowledge our study is the first to uncover a direction-dependent mechanical behavior of the protein coatings and to demonstrate that it affects cellular response relative to substrate mechanics.

cell biology↗

bioRxiv2019

GFP transformation sheds more light on a widespread mycoparasitic interaction

Powdery mildews (PMs), ubiquitous obligate biotrophic plant pathogens, are often attacked in the field by mycoparasitic fungi belonging to the genus Ampelomyces. Some Ampelomyces strains are commercialized biocontrol agents of crop pathogenic PMs. Using Agrobacterium tumefaciens-mediated transformation (ATMT), we produced stable Ampelomyces transformants that constitutively expressed the green fluorescent protein (GFP), to (i) improve the visualization of the PM-Ampelomyces interaction; and (ii) decipher the environmental fate of Ampelomyces before and after acting as a mycoparasite. Detection of Ampelomyces structures, and especially hyphae, was greatly enhanced when diverse PM, leaf and soil samples containing GFP transformants were examined with fluorescence microscopy compared to brightfield and DIC optics. We showed for the first time that Ampelomyces can persist up to 21 days on PM-free host plant surfaces, where it can attack PM structures as soon as these appear after this period. As a saprobe in decomposing, PM-infected leaves on the ground, and also in autoclaved soil, Ampelomyces developed new hyphae, but did not sporulate. These results indicate that Ampelomyces occupies a niche in the phyllosphere where it acts primarily as a mycoparasite of PMs. Our work has established a framework for a molecular genetic toolbox for Ampelomyces using ATMT.

microbiology↗