scholarly journals Length regulation of multiple flagella that self-assemble from a shared pool of components

2018 ◽  
Author(s):  
Thomas G. Fai ◽  
Lishibanya Mohapatra ◽  
Jane Kondev ◽  
Ariel Amir
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Inverse Relationship ◽  
Model Organism ◽  
Growth Dynamics ◽  
Size Control ◽  
Control Model ◽  
Mass Action ◽  
Law Of Mass Action ◽  
Length Regulation ◽  
Coupling Mechanisms

AbstractControl of organelle size is a problem that has intrigued cell biologists for at least a century. The single-celled green algaeChlamydomonas reinhardtiiwith its two 2agella has proved to be a very useful model organism for studies of size control. Numerous experiments have identi1ed motor-driven transport of tubulin to the growing ends of microtubules at the tip of the 2agella as the key component of the machinery responsible for controlling their length. Here we consider a model of 2agellar length control whose key assumption is that proteins responsible for the intra2agellar transport (IFT) of tubulin are present in limiting amounts. We show that this limiting-pool assumption and simple reasoning based on the law of mass action leads to an inverse relationship between the rate at which a 2agellum grows and its length, which has been observed experimentally, and has been shown theoretically to provide a mechanism for length control. Experiments in which one of the two 2agella are severed have revealed the coupled nature of the growth dynamics of the two 2agella, and we extend our length-control model to two 2agella by considering different mechanisms of their coupling. We describe which coupling mechanisms are capable of reproducing the observed dynamics in severing experiments, and why some that have been proposed previously are not. Within our theoretical framework we conclude that if tubulin and IFT proteins are freely exchanged between 2agella simultaneous length control is not possible if the disassembly rate is constant. However, if disassembly depends on the concentration of IFT proteins at the tip of the 2agellum, simultaneous length control can be achieved. Finally, we make quantitative predictions for experiments that could test this model.

scholarly journals Length regulation of multiple flagella that self-assemble from a shared pool of components

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Thomas G Fai ◽  
Lishibanya Mohapatra ◽  
Prathitha Kar ◽  
Jane Kondev ◽  
Ariel Amir
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Green Algae ◽  
Model Organism ◽  
Size Control ◽  
Intraflagellar Transport ◽  
Canonical Model ◽  
Active Disassembly ◽  
Pool Model ◽  
Length Regulation

The single-celled green algae Chlamydomonas reinhardtii with its two flagella—microtubule-based structures of equal and constant lengths—is the canonical model organism for studying size control of organelles. Experiments have identified motor-driven transport of tubulin to the flagella tips as a key component of their length control. Here we consider a class of models whose key assumption is that proteins responsible for the intraflagellar transport (IFT) of tubulin are present in limiting amounts. We show that the limiting-pool assumption is insufficient to describe the results of severing experiments, in which a flagellum is regenerated after it has been severed. Next, we consider an extension of the limiting-pool model that incorporates proteins that depolymerize microtubules. We show that this ‘active disassembly’ model of flagellar length control explains in quantitative detail the results of severing experiments and use it to make predictions that can be tested in experiments.

scholarly journals To Divide or Not to Divide? How Deuterium Affects Growth and Division of Chlamydomonas reinhardtii

Biomolecules ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 861
Author(s):  
Veronika Kselíková ◽  
Vilém Zachleder ◽  
Kateřina Bišová
Keyword(s):  
Cell Cycle ◽  
Chlamydomonas Reinhardtii ◽  
Cell Cycle Progression ◽  
Model Organism ◽  
Cycle Progression ◽  
Synchronous Cultures ◽  
Multiple Fission ◽  
First Choice ◽  
High Doses

Extensive in vivo replacement of hydrogen by deuterium, a stable isotope of hydrogen, induces a distinct stress response, reduces cell growth and impairs cell division in various organisms. Microalgae, including Chlamydomonas reinhardtii, a well-established model organism in cell cycle studies, are no exception. Chlamydomonas reinhardtii, a green unicellular alga of the Chlorophyceae class, divides by multiple fission, grows autotrophically and can be synchronized by alternating light/dark regimes; this makes it a model of first choice to discriminate the effect of deuterium on growth and/or division. Here, we investigate the effects of high doses of deuterium on cell cycle progression in C. reinhardtii. Synchronous cultures of C. reinhardtii were cultivated in growth medium containing 70 or 90% D2O. We characterize specific deuterium-induced shifts in attainment of commitment points during growth and/or division of C. reinhardtii, contradicting the role of the “sizer” in regulating the cell cycle. Consequently, impaired cell cycle progression in deuterated cultures causes (over)accumulation of starch and lipids, suggesting a promising potential for microalgae to produce deuterated organic compounds.

scholarly journals Genetic recombination as a generalised gradient flow

2021 ◽  
Author(s):  
Frederic Alberti
Keyword(s):  
Arbitrary Number ◽  
Genetic Recombination ◽  
Reaction Network ◽  
Gradient Flow ◽  
Mass Action ◽  
Gradient System ◽  
Gradient Structure ◽  
Law Of Mass Action ◽  
Reversible Chemical Reaction ◽  
Time Partitioning

AbstractIt is well known that the classical recombination equation for two parent individuals is equivalent to the law of mass action of a strongly reversible chemical reaction network, and can thus be reformulated as a generalised gradient system. Here, this is generalised to the case of an arbitrary number of parents. Furthermore, the gradient structure of the backward-time partitioning process is investigated.

The Law of Mass Action

2001 ◽  
pp. 121-128
Author(s):  
Bruce Hannon ◽  
Matthias Ruth
Keyword(s):  
Mass Action ◽  
Law Of Mass Action ◽  
The Law

Size Prediction Control Modeling in Cylindrical Grinding

2010 ◽  
Vol 154-155 ◽  
pp. 977-980
Author(s):  
Ning Ding ◽  
Shi Qiang Ma ◽  
Yu Mei Song ◽  
Long Shan Wang
Keyword(s):  
Fuzzy Control ◽  
Model Simulation ◽  
Size Control ◽  
Control Model ◽  
Elman Neural Network ◽  
Cylindrical Grinding ◽  
Control Subsystem ◽  
Control Precision ◽  
Prediction And Control ◽  
Prediction Control

A dynamic size control model during cylindrical grinding is built. The model consists of Elman neural network, fuzzy control subsystem and deformation optimal adaptive control subsystem. To improve the size prediction accuracy, the first and the second derivative of the actual amount removed from the workpiece are added into the Elman network input; To self-adapt and adjust the quantification factor and scale factor in the fuzzy control, the flexible factor is introduced to the fuzzy control model. Simulation and experiment verify that the developed prediction control model is feasible and has high prediction and control precision.

scholarly journals On the Mathematics of the Law of Mass Action

2014 ◽  
pp. 3-46 ◽  
Author(s):  
Leonard Adleman ◽  
Manoj Gopalkrishnan ◽  
Ming-Deh Huang ◽  
Pablo Moisset ◽  
Dustin Reishus
Keyword(s):  
Mass Action ◽  
Law Of Mass Action ◽  
The Law

Dynamics of Consumer-Resource Systems

2013 ◽  
Author(s):  
André M. de Roos ◽  
Lennart Persson
Keyword(s):  
Model Organism ◽  
Growth Dynamics ◽  
Population Cycles ◽  
Food Density ◽  
Juvenile Period ◽  
Ecological Processes ◽  
Resource Dynamics ◽  
Cladoceran Zooplankton ◽  
The Individual ◽  
Consumer Resource

This chapter focuses on consumer-resource dynamics in systems where consumers of different sizes compete for a shared resource. It considers the implications of three important aspects of consumer life history: the explicit handling of a juvenile period leading to a delay between the time when an individual is born to when it starts to reproduce; the rate by which individual ecological processes scale with body size; and whether the rate by which the individual grows is dependent on food density or not. The chapter examines the effects of different resource growth dynamics to illustrate the fundamental differences between population cycles driven by interactions between individuals of different sizes, and classical predator–prey cycles driven by interactions between the consumer and the resource, also referred to as paradox of enrichment cycles. It also discusses experiments with the model organism, the cladoceran zooplankton Daphnia, to elucidate our current understanding of cycles driven by cohort interactions in this organism.

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