APR 15, 2017 5:19 AM PDT

Bacterial Cells Have a Fundamental Size

WRITTEN BY: Carmen Leitch

The expansion of bacterial colonies depends on the availability of sustenance, and when nutrients are good quality, microbes are able to grow bigger and more quickly. There is a principle connecting the size of bacterial cells to their proliferation rate: a growth law. However, that law fails to explain why bacteria, regardless of environmental conditions, divide once they reach a particular size. New work has modified that growth law to resolve this issue.

A team of physicists, biologists and bioengineers from UC San Diego that performed the research have published their findings in the journal Current Biology.

"A few years ago, we set out to do extensive growth inhibition experiments to test the growth law using the model organism Escherichia coli," explained Suckjoon Jun, an assistant professor of physics and molecular biology at UC San Diego, who headed the research effort. "Perhaps not so surprisingly, the original growth law was unable to explain changes in cell size under growth inhibition. Cell size either increased or decreased depending on the inhibition method. Sometimes, cell size did not change at all despite significant growth inhibition."

The research team observed that when the genetic material inside of cells began to replicate in preparation for the division of a cell, the size of the cell tended to stay the same even with all of the changes that were taking place inside of it, such as the synthesis of new proteins, the production of new DNA, various alterations in cell shape and additions to the cell wall. 

"We realized that this invariant cell size represents a fundamental unit of cellular resources required to start growth and the cell cycle, or the 'engine' of a car, so to speak," said Jun. "This 'unit cell' is the fundamental building block of cell size, and cell size is the sum of all invariant unit cells for any growth condition, explaining the origin of the growth law."

Jun credited the advancements of genetic manipulation techniques like the CRISPR gene-editing tool and high-throughput cell sampling tools for enabling his team to harvest a wealth of physiological data from 10 million bacterial cells that were used in their growth inhibition experiments.

Graphical abstract, Si et al Current Biology 2017 - a "quantitative coordination principle of bacterial cell size control under any growth condition"

"This allowed detailed and reliable statistics, and led to quantitative modeling that made experimentally testable predictions, helping us to understand the data at a deeper level," Jun added. "This complements the unexpected 'adder' principle that we discovered a few years ago."

Jun related this process to the techniques of the Danish astronomer Tycho Brahe. Four centuries ago, he was able to convince the German astronomer Johannes Kepler that planetary orbits, whose origin is gravity, were not circles but ellipses through painstaking collection of better orbital data.

"Kepler's elliptical model said nothing about the physical origins of ellipses, but his kinematic modeling was an essential starting point for Newton's work on dynamics 50 years later," Jun explained. "We don't know whether biology is following the footsteps of the history of physics, but examples are accumulating that some branches of biology are becoming as quantitative a science as physics."

You can check out a full lecture from Professor Jun on the coordination of growth and the cell cycle in the video.

 

Sources: AAAS/Eurekalert! via UCSD, Current Biology

About the Author
BS
Experienced research scientist and technical expert with authorships on over 30 peer-reviewed publications, traveler to over 70 countries, published photographer and internationally-exhibited painter, volunteer trained in disaster-response, CPR and DV counseling.
You May Also Like
SEP 26, 2022
Immunology
A Rheumatoid Arthritis-Promoting Molecule is Identified
SEP 26, 2022
A Rheumatoid Arthritis-Promoting Molecule is Identified
Researchers have found that a protein called sulfatase-2 may play a significant role in the tissue damage caused by rheu ...
OCT 11, 2022
Cell & Molecular Biology
Germ Cells Burrow Like Bulldozers
OCT 11, 2022
Germ Cells Burrow Like Bulldozers
In the early embryo, there is a cascade of cellular movement, and all of those cells have to move to the right position ...
OCT 05, 2022
Health & Medicine
SARS-CoV-2 Infects Cells in the Brain & May Cause Structural Changes
OCT 05, 2022
SARS-CoV-2 Infects Cells in the Brain & May Cause Structural Changes
Researchers have now published a study that has revealed how SARS-CoV-2, the virus that causes COVID-19, can infect brai ...
NOV 17, 2022
Cannabis Sciences
What It Means If You Are Ediblocked
NOV 17, 2022
What It Means If You Are Ediblocked
What ediblocking is, and how it affects you
NOV 28, 2022
Drug Discovery & Development
Experimental Drug Lowers 'Bad' Cholesterol by 70%
NOV 28, 2022
Experimental Drug Lowers 'Bad' Cholesterol by 70%
An experimental orally-administered drug reduces 'bad cholesterol' in mice by 70%. The corresponding research wa ...
DEC 03, 2022
Cell & Molecular Biology
A New Form of Antibiotic Resistance is Discovered
DEC 03, 2022
A New Form of Antibiotic Resistance is Discovered
Antibiotic resistance is a growing problem; antibiotic resistant microbes already kill tens of thousands of people aroun ...
Loading Comments...