Computer-assisted beat-pattern analysis and the flagellar waveforms of bovine spermatozoa

Abstract

Obstructed by hurdles in information extraction, handling and processing, computer-assisted sperm analysis systems have typically not considered in detail the complex flagellar waveforms of spermatozoa, despite their defining role in cell motility. Recent developments in imaging techniques and data processing have produced significantly improved methods of waveform digitization. Here, we use these improvements to demonstrate that near-complete flagellar capture is realizable on the scale of hundreds of cells, and, further, that meaningful statistical comparisons of flagellar waveforms may be readily performed with widely available tools. Representing the advent of high-fidelity computer-assisted beat-pattern analysis, we show how such a statistical approach can distinguish between samples using complex flagellar beating patterns rather than crude summary statistics. Dimensionality-reduction techniques applied to entire samples also reveal qualitatively distinct components of the beat, and a novel data-driven methodology for the generation of representative synthetic waveform data is proposed.

Modelling Motility: The Mathematics of Spermatozoa

“…A selection of these approaches are tailored to the morphology and characteristics of spermatozoa (Smith et al, 2009a ; Yang et al, 2014a ; Hansen et al, 2018 ; Gallagher et al, 2019 ), whilst others are somewhat more general (Hongsheng et al, 2009 ; Goldstein et al, 2010 ; Xu et al, 2014 ; Xiao et al, 2016 ; Walker et al, 2019c ); an example output of one of the latter techniques is reproduced in Figure 1A . The development of these software tools and approaches, in combination with improvements in the fidelity of videomicroscopy, has newly enabled studies at scale of the details of flagellar beating in a variety of organisms, including bovine and human spermatozoa (Gallagher et al, 2019 ; Walker et al, 2019d , 2020b ), each analysing hundreds of individual swimmers, with the potential for significant future application and extension.…”

“…Two recent works, however, have sought to address the second of these two drawbacks, applying PCA not just to individual swimmers, but to whole cohorts of swimming cells in order to capture population-level beating information. One, that of Walker et al ( 2020b ), computed time-dependent PCA coefficients and applied standard hypothesis testing techniques to these quantitative measures, enabling statistical comparison between samples of bovine spermatozoa via the details of their beating, coining the term computer-assisted beat-pattern analysis (CABA).…”

“…(D) An example CASA system and cell tracking. (A) is republished from Walker et al ( 2020b ) with permission, under the terms of the Creative Commons Attribution License https://creativecommons.org/licenses/by/4.0/ . (B) is republished with the permission of The Company of Biologists Ltd from Lindemann and Lesich ( 2010 ), permission conveyed through the Copyright Clearance Center, Inc. (D) is reprinted from Amann and Waberski ( 2014 ), with permission from Elsevier.…”

Co-Adaptation of Physical Attributes of the Mammalian Female Reproductive Tract and Sperm to Facilitate Fertilization

“…In forward-moving sperm, the head can be seen to rotate about its longitudinal axis, which is called rolling, or the head can essentially remain within a plane, which is called planar movement [ 19 ]. High speed images of swimming mammalian sperm indicate that the two swimming patterns reflect subtle complex differences in flagellar beating patterns that are not yet well understood [ 20 , 21 , 22 , 23 ].…”

CiliaQ: a simple, open-source software for automated quantification of ciliary morphology and fluorescence in 2D, 3D, and 4D images

“…Our group has released an open-source software for automated, comprehensive characterization of motile cilia and flagella based on 2D light and fluorescence microscopy imaging [ 24 ]. Similar software solutions have been released by other groups [ 25 , 26 ]. However, such analysis approaches are not applicable for cilia in tissues and tissue culture.…”