Flagellar length control in monoflagellates by motorized transport: growth kinetics and correlations of length fluctuations

TL;DR

This paper develops a stochastic model using a 'time of flight' mechanism to explain flagellar length control in monoflagellates, reproducing experimental length variations and analyzing fluctuation correlations during the cell cycle.

Contribution

It introduces a novel stochastic model for flagellar length regulation in monoflagellates based on the ToF mechanism, extending previous work on biflagellates.

Findings

Model reproduces observed flagellar length trends

Correlations in length fluctuations reveal intracellular communication

Monte Carlo simulations validate the model's predictions

Abstract

How does a cell self-organize so that its appendages attain specific lengths that are convenient for their respective functions? What kind of 'rulers' does a cell use to measure the length of these appendages? How does a cell transport structure building materials between the cell body and distal tips of these appendages so as to regulate their dynamic lengths during various stages of its lifetime? Some of these questions are addressed here in the context of a specific cell appendage called flagellum (also called cilium). A "time of flight" (ToF) mechanism, adapted from the pioneering idea of Galileo, has been used successfully very recently to explain the length control of flagella by a biflagellate green algae. Using the same ToF mechanism, here we develop a stochastic model for the dynamics of flagella in two different types of monoflagellate unicellular organisms. A unique feature of these monoflagellates is that these become transiently multi-flagellated during a short span of their life time. The mean length of the flagella in our model reproduce the trend of their temporal variation observed in experiments. Moreover, for probing the intracellular molecular communication between the dynamic flagella of a given cell, we have computed the correlation in the fluctuations of their lengths during the multiflagellated stage of the cell cycle by Monte Carlo simulation.