Author(s): Pintado, P. ; Sampaio, P. ; Tavares, B. ; Montenegro-Johnson, T.D. ; Smith, D.J. ; Lopes, S.S.
Date: 2017
Origin: Repositório Institucional da UNL
Project/scholarship: info:eu-repo/grantAgreement/FCT/3599-PPCDT/125312/PT ; info:eu-repo/grantAgreement/FCT/SFRH/SFRH%2FBPD%2F77258%2F2011/PT;
Subject(s): Cilia length; Flow dynamics; Left–right development
This work was supported by the Fundacao para a Ciencia e a Tecnologia (FCT-ANR/BEX-BID/0153/2012 research grant). T.D.M.-J. was supported by a Royal Commission for the Exhibition of 1851 Fellowship. S.S.L. was funded by FCT Investigator IF/00951/2012. B.T. was funded by FCT fellowship SFRH/BPD/77258/2011 and P.P. and P.S. were funded by the FCT-ANR/BEX-BID/0153/2012 research grant.
Reduction in the length of motile cilia in the zebrafish left– right organizer (LRO), also known as Kupffer’s vesicle, has a large impact on left–right development. Here we demonstrate through genetic overexpression in zebrafish embryos and mathematical modelling that the impact of increased motile cilia length in embryonic LRO fluid flow is milder than that of short cilia. Through Arl13b overexpression, which increases cilia length without impacting cilia beat frequency, we show that the increase in cilium length is associated with a decrease in beat amplitude, resulting in similar flow strengths for Arl13b overexpression and wild-type (WT) embryos, which were not predicted by current theory. Longer cilia exhibit pronounced helical beat patterns and, consequently, lower beat amplitudes relative to WT, a result of an elastohydrodynamic shape transition. For long helical cilia, fluid dynamics modelling predicts a mild (approx. 12%) reduction in the torque exerted on the fluid relative to the WT, resulting in a proportional reduction in flow generation. This mild reduction is corroborated by experiments, providing a mechanism for the mild impact on organ situs. ©2017 The Authors.
