Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

'Snooze button' on biological clocks improves cell adaptability

18.02.2013
The circadian clocks that control and influence dozens of basic biological processes have an unexpected "snooze button" that helps cells adapt to changes in their environment.
A study by Vanderbilt University researchers published online Feb. 17 by the journal Nature provides compelling new evidence that at least some species can alter the way that their biological clocks function by using different "synonyms" that exist in the genetic code.

"This provides organisms with a novel and previously unappreciated mechanism for responding to changes in their environment," said Professor of Biological Sciences Carl Johnson. He and Associate Professor of Biological Sciences Antonis Rokas collaborated on the study.

Like many written languages, the genetic code is filled with synonyms: differently spelled "words" that have the same or very similar meanings. For a long time, biologists thought that these synonyms, called synonymous codons, were in fact interchangeable. Recently, they have realized that this is not the case and that differences in synonymous codon usage have a significant impact on cellular processes, so scientists have advanced a wide variety of ideas about the role that these variations play.

The new insight is not only an important advance in understanding evolution at the molecular level, but it also has potential applications in biotechnology, such as biofuel production, and gene therapy.

"While biological clocks are vital to maintaining healthy patterns of sleep, metabolism, physiology and behavior, under certain environmental conditions strict adherence to these rhythms can be disadvantageous," said Michael Sesma of the National Institute of General Medical Sciences, which partially funded the work. "This work shows how organisms can ignore the clock under certain circumstances—much like hitting a biological snooze button on the internal timepiece—and enhance their survival in the face of ever-changing circumstances."

The basic letters of the genetic code are a quartet of molecules (nucleic acids) designated A, C, G and U. These are combined into 61 triplets called codons, which are analogous to words. The codons provide the blueprints that the cell's protein-building machinery uses to generate amino acids, which are the basic building blocks that make all the proteins found in living organisms. However, cells only use 20 amino acids. That means a number of amino acids are produced by several different codons. For example, CCA, CCG and CCC are synonymous codons because they all encode for the same amino acid, proline.

It turns out that there is a reason for this redundancy. Some codons are faster and easier for cells to process and assemble into proteins than others. Recognition of this difference led to the concept of optimal codons and the hypothesis that natural selection should drive organisms – particularly fast growing ones – to use genes that use optimal codons to make critical proteins that need to be highly abundant or synthesized rapidly in cells.

The problem with this hypothesis was shown by Johnson and Rokas' study of the effect of changing codon usage on the simple biological clock found in single-celled cyanobacteria (blue-green algae) and a similar study of the more complex biological clock found in bread mold performed by a team led by Yi Liu that were published together.

"What the Liu team found was that optimizing all the codons used by the fungal biological clock knocked the clock out, which was totally unexpected! Those researchers concluded that clock proteins in the fungus are not properly assembled if they are synthesized too rapidly; it's as if the speed of one's writing affected our ability to read the text," Johnson summarized.

In the cyanobacteria, however, the researchers observed a different phenomenon. At Vanderbilt, Research Associate Professor Yao Xu optimized the codons in the cyanobacteria's biological clock. This did not shut the clock down in the algae, but it did have a more subtle, but potentially as profound effect: It significantly reduced cell survival at certain temperatures.

"Xu figured that the biological clock with optimized codons might work better at lower temperatures and it did," Johnson said. However the substitution also modified the biological clock so it ran with a longer, 30-hour period. When forced to operate in a 24-hour daily light/dark cycles, the bacteria with the optimized clock grew significantly slower than "wild-type" cells. "In cyanobacteria, it's as if writing speed changes the meaning," said Rokas.

The potential importance of changes in synonymous codon usage in adapting to environmental factors is magnified by the fact that they can influence the operation of biological clocks, which function as a key adaptation to daily environmental rhythms. Biological clocks control and influence dozens of different basic biological processes, including sleeping and feeding patterns, core body temperature, brain activity, hormone production and cell regeneration.

"It is now clear that variations in codon usage is a fundamental and underappreciated form of gene regulation," said Rokas.

Recognition of the importance of this process has a number of potential applications in biotechnology. For example, "it should be possible to improve the ability of algae to robustly express biofuel-producing proteins from other organisms by optimizing the codons that they use," Johnson said.

Vanderbilt graduate student Peijun Ma, postdoctoral fellow Premal Shah from the University of Pennsylvania and Yi Liu, professor at the University of Texas Southwestern Medical Center also contributed to the study, which was funded by grants from the National Institute of General Medical Sciences (GM067152, GM088595, GM068496 & GM062591), the Welch Foundation (I-1560), the National Science Foundation (DEB-0844968), the Burroughs Wellcome Fund and a David & Lucille Packard Foundation Fellowship.

Visit Research News @ Vanderbilt for more research news from Vanderbilt. [Media Note: Vanderbilt has a 24/7 TV and radio studio with a dedicated fiber optic line and ISDN line. Use of the TV studio with Vanderbilt experts is free, except for reserving fiber time.]

David Salisbury | EurekAlert!
Further information:
http://www.vanderbilt.edu

More articles from Life Sciences:

nachricht Identifying drug targets for leukaemia
02.05.2016 | The Hong Kong Polytechnic University

nachricht A cell senses its own curves: New research from the MBL Whitman Center
29.04.2016 | Marine Biological Laboratory

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: 2+1 is Not Always 3 - In the microworld unity is not always strength

If a person pushes a broken-down car alone, there is a certain effect. If another person helps, the result is the sum of their efforts. If two micro-particles are pushing another microparticle, however, the resulting effect may not necessarily be the sum their efforts. A recent study published in Nature Communications, measured this odd effect that scientists call “many body.”

In the microscopic world, where the modern miniaturized machines at the new frontiers of technology operate, as long as we are in the presence of two...

Im Focus: Tiny microbots that can clean up water

Researchers from the Max Planck Institute Stuttgart have developed self-propelled tiny ‘microbots’ that can remove lead or organic pollution from contaminated water.

Working with colleagues in Barcelona and Singapore, Samuel Sánchez’s group used graphene oxide to make their microscale motors, which are able to adsorb lead...

Im Focus: ORNL researchers discover new state of water molecule

Neutron scattering and computational modeling have revealed unique and unexpected behavior of water molecules under extreme confinement that is unmatched by any known gas, liquid or solid states.

In a paper published in Physical Review Letters, researchers at the Department of Energy's Oak Ridge National Laboratory describe a new tunneling state of...

Im Focus: Bionic Lightweight Design researchers of the Alfred Wegener Institute at Hannover Messe 2016

Honeycomb structures as the basic building block for industrial applications presented using holo pyramid

Researchers of the Alfred Wegener Institute (AWI) will introduce their latest developments in the field of bionic lightweight design at Hannover Messe from 25...

Im Focus: New world record for fullerene-free polymer solar cells

Polymer solar cells can be even cheaper and more reliable thanks to a breakthrough by scientists at Linköping University and the Chinese Academy of Sciences (CAS). This work is about avoiding costly and unstable fullerenes.

Polymer solar cells can be even cheaper and more reliable thanks to a breakthrough by scientists at Linköping University and the Chinese Academy of Sciences...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

The “AC21 International Forum 2016” is About to Begin

27.04.2016 | Event News

Soft switching combines efficiency and improved electro-magnetic compatibility

15.04.2016 | Event News

Grid-Supportive Buildings Give Boost to Renewable Energy Integration

12.04.2016 | Event News

 
Latest News

Identifying drug targets for leukaemia

02.05.2016 | Life Sciences

Clay nanotube-biopolymer composite scaffolds for tissue engineering

02.05.2016 | Materials Sciences

NASA's Fermi Telescope helps link cosmic neutrino to blazar blast

02.05.2016 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>