Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Copy/paste and delete – or how to thrive without gene regulation

10.03.2020

Turning genes on and off as needed allows an organism to adapt to changes in the environment—provided the organism has a specific regulatory design in place. Scientists from the Institute of Science and Technology Austria (IST Austria) have shown that under rare or rapidly changing conditions, the fitness of a population of bacteria can increase simply by producing a higher number of copies of one and the same gene. The results are highly relevant in resistance to antibiotics treatment. The study was published in Nature Ecology & Evolution.

Natural environments are constantly changing. If the change is a familiar one—like the shift from day to night or fluctuation in food supply—organisms use gene regulation to adapt, allowing individual genes to be turned on and off as needed. However, an organism may face fundamentally new conditions for which it has not yet evolved an adequate gene regulation mechanism.


Flourescent E. coli populations in a Petri dish

IST Austria – Guet Gruppe

The evolution of such a mechanism takes a very long time—up to millions of years—, as the process depends on rare point mutations to occur, and the right mutations may not happen fast enough if conditions change rapidly. PhD students Isabella Tomanek and Rok Grah from the groups of Calin Guet and Gašper Tkačik at the Institute of Science and Technology Austria (IST Austria) and Jonathan Bollback at University of Liverpool, UK, were thus wondering if another evolutionary solution—gene copying—may step in to support the survival of a bacterial population under rapidly changing conditions.

Copy/paste and delete create genetic diversity

Like any other mutation, the copying of genes happens spontaneously and all the time. “A typical bacterial population will contain a large fraction of cells with a duplication somewhere in their chromosome”, explains Isabella Tomanek. “We looked at over 40 generations of individual bacteria and visualized these duplications, but we also saw that they are quite unstable:

The second copy of a gene may be amplified further in the next generations to come and thus lead to large copy numbers, but the duplication may also be deleted again right away, and the individual falls back to the original single-gene state.”

This instability causes variation in gene copy numbers and thus in gene expression levels of a population (as any extra gene copy boosts the expression of a gene). In turn, selection could act on the resulting diversity of copy numbers—and pick those bacteria with the “right” amount of copies/level of gene expression.

Quick changes ask for quick strategies

To test their hypothesis, the scientists investigated the expression of a model gene relevant for the growth of Escherichia coli in two different sugar environments: galactose on the one hand, selecting for high expression of the model gene to support growth (environment A), and a chemical analog of galactose on the other hand, which supports growth only when gene expression is low (environment B).

By switching between these two opposing environments following a 24-hour rhythm, the scientists simulated a relatively rapid change of growth conditions selecting for the regulation of the model gene. As expected, Tomanek et al. observed that the populations tuned their gene expression to the two environments as needed—high gene expression in environment A as opposed to low gene expression in environment B.

These experimental results were taken up by Rok Grah from the biophysics theory group of Gašper Tkačik, who cast the data into a population-dynamics model. Uniting their work in this study, the three groups have demonstrated for the first time that gene copying serves as a strategy to tune the level of gene expression when gene regulation is required but no other genetic regulatory mechanism is in place.

Rok Grah: “Most notably, the copy/paste and delete strategy comes into effect on ecological timescales, i.e. before slower evolutionary solutions like gene regulation on the level of single cells can evolve by adaptation through point mutations. And, as we could show in our model, since any genomic region can basically be amplified, the described mechanism cannot only act on any bacterial gene but it is also applicable, in principle, to any other organism.”

Implications for antibiotic resistance

The broad applicability of the genetic mechanism described in this study has potential implications for an equally diverse number of biological phenomena. For instance, it may lead to failure of antibiotics because, due to a difference in copy numbers, bacteria from one and the same patient show different levels of antibiotic resistance. This phenomenon called heteroresistance makes it hard for physicians to estimate just how much antibiotic is needed to successfully fight a bacterial infection.

Originalpublikation:

Tomanek I, Grah R, Lagator M, Andersson AMC, Bollback JP, Tkačik G & Guet CC. 2020. Gene amplification as a form of population-level gene expression regulation. Nature Ecology & Evolution. DOI: 10.1038/s41559-020-1132-7

Patrick Müller | idw - Informationsdienst Wissenschaft

More articles from Life Sciences:

nachricht X-ray scattering shines light on protein folding
10.07.2020 | The Korea Advanced Institute of Science and Technology (KAIST)

nachricht Surprisingly many peculiar long introns found in brain genes
10.07.2020 | Moscow Institute of Physics and Technology

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: The spin state story: Observation of the quantum spin liquid state in novel material

New insight into the spin behavior in an exotic state of matter puts us closer to next-generation spintronic devices

Aside from the deep understanding of the natural world that quantum physics theory offers, scientists worldwide are working tirelessly to bring forth a...

Im Focus: Excitation of robust materials

Kiel physics team observed extremely fast electronic changes in real time in a special material class

In physics, they are currently the subject of intensive research; in electronics, they could enable completely new functions. So-called topological materials...

Im Focus: Electrons in the fast lane

Solar cells based on perovskite compounds could soon make electricity generation from sunlight even more efficient and cheaper. The laboratory efficiency of these perovskite solar cells already exceeds that of the well-known silicon solar cells. An international team led by Stefan Weber from the Max Planck Institute for Polymer Research (MPI-P) in Mainz has found microscopic structures in perovskite crystals that can guide the charge transport in the solar cell. Clever alignment of these "electron highways" could make perovskite solar cells even more powerful.

Solar cells convert sunlight into electricity. During this process, the electrons of the material inside the cell absorb the energy of the light....

Im Focus: The lightest electromagnetic shielding material in the world

Empa researchers have succeeded in applying aerogels to microelectronics: Aerogels based on cellulose nanofibers can effectively shield electromagnetic radiation over a wide frequency range – and they are unrivalled in terms of weight.

Electric motors and electronic devices generate electromagnetic fields that sometimes have to be shielded in order not to affect neighboring electronic...

Im Focus: Gentle wall contact – the right scenario for a fusion power plant

Quasi-continuous power exhaust developed as a wall-friendly method on ASDEX Upgrade

A promising operating mode for the plasma of a future power plant has been developed at the ASDEX Upgrade fusion device at Max Planck Institute for Plasma...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Contact Tracing Apps against COVID-19: German National Academy Leopoldina hosts international virtual panel discussion

07.07.2020 | Event News

International conference QuApps shows status quo of quantum technology

02.07.2020 | Event News

Dresden Nexus Conference 2020: Same Time, Virtual Format, Registration Opened

19.05.2020 | Event News

 
Latest News

X-ray scattering shines light on protein folding

10.07.2020 | Life Sciences

Looking at linkers helps to join the dots

10.07.2020 | Materials Sciences

Surprisingly many peculiar long introns found in brain genes

10.07.2020 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>