Synchronization of Cilia and Flagella - 2 by Benjamin Friedrich

DISCUSSION MEETING : THIRSTING FOR THEORETICAL BIOLOGY (ONLINE) ORGANIZERS : Vaishnavi Ananthanarayanan (UNSW & EMBL Australia), Vijaykumar Krishnamurthy (ICTS-TIFR, India) and Vidyanand Nanjundiah (Centre for Human Genetics, India) DATE : 11 January 2021 to 22 January 2021 VENUE : Online Contemporary research in biology is increasingly becoming more quantitative in nature. As such, "...we are drowning in a sea of data and thirsting for some theoretical framework with which to understand it" [Brenner (2012)]. The absence of meaningful exchanges between experimentalists and theoreticians is a glaring reason for this state of affairs. The broad aim of the second edition of "Thirsting for theoretical biology" is to expose people who have a background in the physical and mathematical sciences to a range of interesting biological phenomena at the cellular and tissue level as experimentalists view them. The meeting will showcase examples of theory-experiment interactions that can deepen our understanding of living matter and will also feature a panel discussion titled 'What is theoretical biology?'. In addition, there will be a discussion, aimed mainly at students, on why theoretical and quantitative biology offers exciting prospects for a research career. The topics to be covered in the meeting will include the regulation of genetic activity, chromosome dynamics, cytoskeletal organisation, molecular motors, cellular energetics, stem cell behaviour, cell-cell interactions, developmental homeostasis and morphogenesis. CONTACT US [email protected] PROGRAM LINK https://www.icts.res.in/discussion-me... Table of Contents (powered by https://videoken.com) 0:01:04 Cilium = Eukaryotic flagellum 0:02:30 The flagellum contains a regular motor-filament array 0:03:24 Molecular motors convert chemical energy into work 0:03:57 A dynamic instability generates motor oscillations 0:04:44 The beating flagellum is a biological oscillator 0:07:56 The flagellum is a noisy oscillator 0:08:36 Direct measurements of noisy oscillations 0:11:46 Limit cycle of flagella oscillations 0:12:35 Phase and amplitude fluctuations 0:14:01 The quality factor quantifies phase fluctuations 0:15:06 Flagella fluctuations are orders of magnitude larger than thermal noise 0:16:30 Theory of noisy motor oscillations 0:18:15 Motors stochastically bind to neighbor filament 0:18:51 Filaments are coupled visco-elastically 0:19:47 Our theory applies to different motor systems 0:21:27 Is flagella noise relevant? 0:21:51 Amplitude fluctuations imply noisy swimming 0:29:00 Molecular motors bend the flagellum 0:31:01 Bending waves of beating flagella can synchronize 0:31:42 Collections of cilia synchronize in metachronal waves 0:32:50 Cilia carpets clear pathogens from airways 0:33:43 Cilia synchronization by hydrodynamic interactions? 0:34:59 Hydrodynamic interactions give coupling at a distance 0:36:16 Flagella can synchronize by hydrodynamic interactions 0:36:52 Synchronization of cilia and flagella 0:37:37 Chlamydomonas. A model organism for flagella synchronization 0:38:13 Pairs of cilia synchronize in Chlamydomonas 0:39:06 A weak coupling can synchronize oscillators 0:39:57 A weak coupling can synchronize oscillators: Table top experiment 0:40:53 Basic theory: The Adler equation 0:42:38 In-phase and anti-phase synchronization 0:43:47 Noise causes occasional phase slips 0:44:22 Synchronization despite small frequency mismatch A AW 0, 20 0:44:45 Large frequency mismatch causes phase drift 0:45:15 Minimal models of hydrodynamic synchronization 0:46:27 Symmetries prevent synchronization 0:47:51 Three mechanisms of hydrodynamic synchronization 0:48:31 What couples flagella oscillators? 0:50:08 How do flagella sense physical forces? 0:50:53 Direct measurements of cilia load response 0:51:46 Flagella shape is represented by phase and amplitude 0:52:52 External flows change the speed of the beat 0:54:35 Phase speed changes under load 0:55:26 Lagrangian mechanics of flagella oscillations 0:57:34 Energy balance of the flagella beat 0:59:30 Single fit parameter 1:01:13 Test of theory: Phase-locking to external oscillatory flow 1:03:31 Flagella energy efficiency sets synchronization strength 1:05:49 Probing stronger flows 1:06:12 Strong flows stall the flagella beat 1:07:28 Motor oscillations 1:14:24 Synchronization by mechanical self-stabilization 1:17:22 Perfect synchronization in the absence of noise 1:18:35 Two more ingredients ... 1:19:03 Phase-diagram of flagella synchronization 1:21:03 Summary 1:21:37 We apply the phase-oscillator description to cilia carpets 1:22:37 Hydrodynamic friction forces (x) 1:23:39 Multi-scale model of a cilia carpet 1:24:25 Reciprocal lattice of possible metachronal wave modes 1:25:12 Cilia beat faster for in-phase coordination 1:25:44 Multiple wave modes are stable 1:26:56 Switching on active cilia noise: Abrupt loss of local synchronization at critical noise 1:29:00 Quantifying noise in cilia carpets