3D morphology of an outer-hair-cell hair bundle increases its displacement and dynamic range

In mammals, outer-hair-cell hair bundles (OHBs) transduce sound-induced forces into receptor currents and are required for the wide dynamic range and high sensitivity of hearing. OHBs differ conspicuously in morphology from other types of bundles. Here, we show that the 3D morphology of an OHB greatly impacts its mechanics and transduction. An OHB comprises rod-like stereocilia, which pivot on the surface of its sensory outer hair cell. Stereocilium pivot positions are arranged in columns and form a V shape. We measure the pivot positions (3D fluorescence microscopy z-slices in lif file, jpg of a single slice, pivot coordinates in xlsx file) and determine that OHB columns are far from parallel (Mathematica code). To calculate the consequences of an OHB’s V shape and far-from-parallel columns, we develop a mathematical model of an OHB that relates its pivot positions, 3D morphology, mechanics, and receptor current (Mathematica code). We find that the 3D morphology of the OHB can halve it..., Sample preparation
Sprague-Dawley rats of both sexes were sacrificed by decapitation using methods approved by the Stanford University Administration Panel on Laboratory Animal Care. The midapical turn (1-2 mm from the apex) of isolated organs of Corti were dissected from pups at postnatal day 10 (P10). Dissections were done in extracellular solution containing (in mM): 142 NaCl, 2 KCl, 2 CaCl2, 1 MgCl2, 10 HEPES, 6 Glucose, 2 Ascorbate/Pyruvate, 2 Creatine monohydrate, at pH 7.4 and a final osmolality of 304-307 mOsm. The tectorial membrane was slightly lifted using a needle tip and gently removed with a fine forceps. Each sample was then transferred to a dish containing fixative (4% paraformaldehyde in PBS) for 30 mins. The sample was washed three times, 5 min/wash, with PBS and permeabilized at room temperature in PBS containing 0.1% Triton X-100 for 20 mins. The sample was then blocked with 5% FBS (foetal bovine serum) in PBS for 1 h at room temperature. The sample was subsequently..., , # Data from: 3D Morphology of an Outer-Hair-Cell Hair Bundle Increases Its Displacement and Dynamic Range

#### Zhu3DOHB

[https://doi.org/10.5061/dryad.4mw6m90h4](https://doi.org/10.5061/dryad.4mw6m90h4)

* Fluorescence z-stack stored in lif file.
* z-stack analysis output in jpg and xlsx files.
* xlsx input to PivotPointAnalysis.nb for analysis.
* nb files contain mathematical modeling code.
* Numerical results of the mathematical modeling are in the mx files.

## Description of the data and file structure

lif file contains z-stack of fluorescence data. Open with Leica Application Suite or ImageJ.
JPEG output from ImageJ of one z-slice.
xlsx file of putative pivot points output from ImageJ. Open with Excel.

## Code/Software

* Mathematica 13: PivotPointAnalysis.nb code imports data from xlsx file and analyses pivot points.
* Mathematica 13: IdenticalColumnsOHB.nb code for Identical Columns Mathematical Model. Results stored in IdenticalColumnsOHB*.mx file, which can be loaded at sta...