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Full-Text Articles in Physical Sciences and Mathematics
Microtubule Seams Are Not Mechanically Weak Defects, Taviare Hawkins
Microtubule Seams Are Not Mechanically Weak Defects, Taviare Hawkins
Physics Faculty Scholarship
Microtubule rigidity is important for many cellular functions to support extended structures and rearrange materials within the cell. The arrangement of the tubulin dimers within the microtubule can be altered to affect the protofilament number and the lattice type. Prior electron microscopy measurements have shown that when polymerized in the presence of a high concentration of NaCl, microtubules were more likely to be ten protofilaments with altered intertubulin lattice types. Specifically, such high-salt microtubules have a higher percentage of seam defects. Such seams have long been speculated to be a mechanically weak location in the microtubule lattice, yet no experimental …
Control Of Molecular Shuttles By Designing Electrical And Mechanical Properties Of Microtubules, Taviare Hawkins
Control Of Molecular Shuttles By Designing Electrical And Mechanical Properties Of Microtubules, Taviare Hawkins
Physics Faculty Scholarship
Kinesin-driven microtubules have been focused on to serve as molecular transporters, called “molecular shuttles,” to replace micro/nanoscale molecular manipulations necessitated in micro total analysis systems. Although transport, concentration, and detection of target molecules have been demonstrated, controllability of the transport directions is still a major challenge. Toward broad applications of molecular shuttles by defining multiple moving directions for selective molecular transport, we integrated a bottom-up molecular design of microtubules and a top-down design of a microfluidic device. The surface charge density and stiffness of microtubules were controlled, allowing us to create three different types of microtubules, each with different gliding …
Perturbations In Microtubule Mechanics From Tubulin Preparation, Taviare Hawkins
Perturbations In Microtubule Mechanics From Tubulin Preparation, Taviare Hawkins
Physics Faculty Scholarship
Microtubules are essential structures for cellular organization. They support neuronal processes and cilia, they are the scaffolds for the mitotic spindle, and they are the tracks for intracellular transport that actively organizes material and information within the cell. The mechanical properties of microtubules have been studied for almost 30 years, yet the results from different groups are startlingly disparate, ranging over an order of magnitude. Here we present results demonstrating the effects of purification, associated-protein content, age, and fluorescent labeling on the measured persistence length using the freely fluctuating filament method. We find that small percentages (<1%) of residual microtubule-associated proteins left over in the preparation can cause the persistence length to double, and that these proteins also affect the persistence length over time. Interestingly, we find that the fraction of labeled tubulin dimers does not affect the measured persistence length. Further, we have enhanced the analysis method established by previous groups. We have added a bootstrapping with resampling analysis to estimate the error in the variance data used to determine the persistence length. Thus, we are able to perform a weighted fit to the data to more accurately determine the persistence length.