Human sperm uses asymmetric and anisotropic flagellar controls to regulate swimming symmetry and cell steering
Authors: Gabriel Corkidi
Paul Hernández-Herrera
Hermes Gadêlha
Fernando Montoya
Alberto Darszon
Journal: Science Advances (2020)
Discipline: Multidisciplinary
Keywords: Flagellar beating; sperm; asymmetry; molecular components; swimming
Affiliations: Department of Engineering Mathematics, University of Bristol, BS8 1UB Bristol, UK., Laboratorio de Imágenes y Visión por Computadora, Departamento de Ingeniería Celular y Biocatálisis, Universidad Nacional Autónoma de México, Cuernavaca, Mexico., Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Mexico.

Abstract:  Flagellar beating drives sperm through the female reproductive tract and is vital for reproduction. Flagellar waves are generated by thousands of asymmetric molecular components; yet, paradoxically, forward swimming arises via symmetric side-to-side flagellar movement. This led to the preponderance of symmetric flagellar control hypotheses. However, molecular asymmetries must still dictate the flagellum and be manifested in the beat. Here, we reconcile molecular and microscopic observations, reconnecting structure to function, by showing that human sperm uses asymmetric and anisotropic controls to swim. High-speed three-dimensional (3D) microscopy revealed two coactive transversal controls: An asymmetric traveling wave creates a one-sided stroke, and a pulsating standing wave rotates the sperm to move equally on all sides. Symmetry is thus achieved through asymmetry, creating the optical illusion of bilateral symmetry in 2D microscopy. This shows that the sperm flagellum is asymmetrically controlled and anisotropically regularized by fast-signal transduction. This enables the sperm to swim forward. 

Retracted: No

PubPeer comments:
 Editorial expression of concern - Science Advances 14 Aug 2020:  In the 31 July 2020 issue, Science Advances published the Research Article u201cHuman sperm uses asymmetric and anisotropic flagellar controls to regulate swimming symmetry and cell steeringu201d by H. Gadu00ealha, P. Hernu00e1ndez-Herrera, F. Montoya, A. Darszon, and G. Corkidi (1). The corresponding authors have now notified Science Advances of the concern that, upon reexamination, sections of the mathematical analysis in the paper are not fully able to either prove or disprove a core conclusion of the article, namely that the flagellar beat in human sperm is asymmetric. A re-analysis by the authors is underway, and Science Advances is publishing this Editorial Expression of Concern to alert our readers while we await the outcome. , 
 Copy pasted from https: advances.sciencemag.org content 7 21 eaau9116 :  Retraction of the Research Article: u201cHuman sperm uses asymmetric and anisotropic flagellar controls to regulate swimming symmetry and cell steeringu201d In our recent Research Article (1), we presented experimental observations of high-precision tracking of human sperm flagellum in 3D and flagellar waveform analysis. After publication, readers identified that although our 3D flagellar experimental data and analyses are sound, the conclusion of flagellar asymmetry and anisotropy cannot be drawn unequivocally using only 3D flagellar waveform data. Because of this, the description of asymmetry and anisotropy in the article is currently incomplete. As such, we are retracting the Research Article. We regret this was not found sooner and we are grateful to the scientific community for the swift responses and discussions of our work. Science Advances 19 May 2021: Vol. 7, no. 21, eaau9116 See also https: retractionwatch.com 2021 05 19 paper-likening-human-sperm-to-playful-otters-retracted ,