Navigation Links
Researchers show how 1 gene becomes 2 (with different functions)
Date:1/12/2011

CHAMPAIGN, Ill. Researchers report that they are the first to show in molecular detail how one gene evolved two competing functions that eventually split up via gene duplication to pursue their separate destinies.

The study, in the Proceedings of the National Academy of Sciences, validates a decades-old hypothesis about a key mechanism of evolution. The study also confirms the ancestry of a family of "antifreeze proteins" that helps the Antarctic eelpout survive in the frigid waters of the Southern Ocean.

"I'm always asking the question of where these antifreeze proteins come from," said University of Illinois animal biology professor Christina Cheng, who has spent three decades studying the genetic adaptations that enable Antarctic fish to survive in one of the coldest zones on the planet. "The cell usually does not create new proteins from scratch."

Scientists have known since 2001 that the sequence of genes coding for a family of antifreeze proteins (known as AFP III) was very similar to part of a sequence of a gene that codes for a cellular enzyme in humans. Since Antarctic fish also produce this enzyme, sialic acid synthase (SAS), it was thought that the genes for these antifreeze proteins had somehow evolved from a duplicate copy of the SAS gene. But no study had shown how this happened with solid experimental data.

Cheng and her colleagues at the Chinese Academy of Sciences began by comparing the sequences of the SAS and AFP III genes. There are two SAS genes in fish: SAS-A and SAS-B. The researchers confirmed that the AFP III genes contain sequences that are most similar to those in a region of SAS-B.

They also found a sequence in the SAS-B gene that, when translated into a new protein, could with a few modifications direct the cell to secrete the protein. This slightly modified signal sequence also appears in the AFP III genes. Unlike the SAS enzymes, which remain inside the cell, the AFP III proteins are secreted into the blood or extracellular fluid, where they can more easily disrupt the growth of invading ice crystals.

"This basically demonstrates how something that 'lives' inside the cell can acquire this new functionality and get moved out into the bloodstream to do something else," Cheng said.

Further analysis revealed that the SAS proteins function as enzymes but also have modest ice-binding capabilities. This finding supports a decades-old hypothesis that states that when a single gene begins to develop more than one function, duplication of that gene could result in the divergent evolution of the original gene and its duplicate.

The new finding also supports the proposed mechanism, called "escape from adaptive conflict," by which this can occur. According to this idea, if a gene has more than one function, mutations or other changes to the gene through natural selection that enhance one function may undermine its other function.

"The original enzyme function and the emerging ice-binding function of the ancestral SAS molecule might conflict with each other," Cheng said. When the SAS-B gene became duplicated as a result of a copying error or some other random event in the cell, she said, then each of the duplicate genes was freed from the conflict and "could go on its own evolutionary path."

"This is the first clear demonstration with strong supporting molecular and functional evidence of escape from adaptive conflict as the underlying process of gene duplication and the creation of a completely new function in one of the daughter copies," Cheng said. "This has not been documented before in the field of molecular evolution."

Cheng said that even before the gene for the secreted antifreeze protein was formed, the original SAS protein appears to have had both the enzymatic and ice-binding functions. This suggests that somehow the SAS protein (which is not secreted) acted within the cell to disrupt the growth of ice.

This could have occurred "in the early developmental stages of the fish," Cheng said, since the eggs are spawned into a cold environment and would benefit from even the modest antifreeze capabilities of the SAS protein.

Later, after the SAS gene was duplicated and the AFP gene went on its own evolutionary path, Cheng said, the antifreeze protein appears to have evolved into a secreted protein, allowing it to disrupt ice formation in the bloodstream and extracellular fluid, where it would be of most benefit to the adult fish.


'/>"/>

Contact: Diana Yates
diya@illinois.edu
217-333-5802
University of Illinois at Urbana-Champaign
Source:Eurekalert  

Related biology news :

1. NC State researchers get to root of parasite genome
2. Researchers find animal with ability to survive climate change
3. Researchers find an essential gene for forming ears of corn
4. Researchers note differences between people and animals on calorie restriction
5. Researchers study acoustic communication in deep-sea fish
6. Researchers discover that growing up too fast may mean dying young in honey bees
7. Researchers study how pistachios may improve heart health
8. UI researchers find potentially toxic substance present in Chicago air
9. Researchers develop new self-training gene prediction program for fungi
10. Case Western Reserve University researchers track Chernobyl fallout
11. Childrens National researchers develop novel anti-tumor vaccine
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
Researchers show how 1 gene becomes 2 (with different functions)
(Date:2/16/2017)... 2017  Genos, a community for personal genetic ... received Laboratory Accreditation from the College of American ... laboratories that meet stringent requirements around quality, accuracy ... "Genos is committed to maintaining the ... honored to be receiving CAP accreditation," said ...
(Date:2/13/2017)... Former 9/11 Commission border counsel and Special ... Kephart of Identity Strategy Partners, LLP, today releases ... "Executive Order: Protecting the Nation From Foreign Terrorist Entry ... "As President Trump,s ,Travel Ban, Executive Order gains more ... the travel ban, it is important that our national ...
(Date:2/8/2017)... Feb. 8, 2017 About Voice Recognition Biometrics ... match it against a stored voiceprint template. Acoustic ... cadence, and tone are compared to distinguish between ... installation, as most PCs already have a microphone ... Voice recognition biometrics are most likely to be ...
Breaking Biology News(10 mins):
(Date:3/23/2017)... ... ... is proud to announce it has become the premiere team-building cooking event company in San ... world, such as Illumina, HP and Qualcomm, and is ranked #1 in its category on ... to its new team building format, a way for teams to not only interact with ...
(Date:3/23/2017)... -- BioPharmX Corporation (NYSE MKT: BPMX), a specialty pharmaceutical ... reported financial results for the quarter and year ... update on the company,s clinical development efforts and ... pleased to report that last year was a ... Krammer. "We achieved key clinical milestones and attracted ...
(Date:3/23/2017)... , March 23, 2017  Agriculture technology company Cool ... financing and note conversion to commercialize its Cool Terra ... focused on developing products that are simultaneously profitable as ... in the last 18 months. This latest round of ... Venture Partners. The company,s primary product, ...
(Date:3/22/2017)... March 22, 2017  Ascendis Pharma A/S (Nasdaq: ... TransCon technology to address significant unmet medical needs ... the full year ended December 31, 2016. ... our company as we broadened our pipeline and ... rare disease company with an initial focus on ...
Breaking Biology Technology: