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:8/23/2017)... ARMONK, N.Y. , Aug. 23, 2017  The general public,s help ... the human microbiome—the bacteria that live in and on the human body ... ... bacteria in the human microbiome, starting with the gut. The project's goal ... in disease. Photo credit: IBM ...
(Date:6/23/2017)... and ITHACA, N.Y. , ... and Cornell University, a leader in dairy research, today ... bioinformatics designed to help reduce the chances that the ... the onset of this dairy project, Cornell University has ... for Sequencing the Food Supply Chain, a food safety ...
(Date:5/16/2017)... DALLAS , May 16, 2017   ... for health organizations, and MD EMR Systems ... certified development partner for GE, have established a ... Patient Portal product and the GE Centricity™ products, ... Centricity EMR. These new integrations ...
Breaking Biology News(10 mins):
(Date:10/10/2017)... PITTSBURGH, PA (PRWEB) , ... October 10, 2017 ... ... this year’s recipients of 13 prestigious awards honoring scientists who ... be presented in a scheduled symposium during Pittcon 2018, the world’s leading conference ...
(Date:10/9/2017)... (PRWEB) , ... October 09, 2017 , ... At its ... Dr. Christopher Stubbs, a professor in Harvard University’s Departments of Physics and Astronomy, has ... was a member of the winning team for the 2015 Breakthrough Prize in Fundamental ...
(Date:10/7/2017)... ... October 06, 2017 , ... ... providing advanced instruments and applications consulting for microscopy and surface analysis, Nanoscience ... application consulting, Nanoscience Analytical offers a broad range of contract analysis services ...
(Date:10/6/2017)... ... October 06, 2017 , ... ... the healthcare and technology sector at their fourth annual Conference where founders, investors, ... inspiring speakers and the ELEVATE pitch competition showcasing early stage digital health and ...
Breaking Biology Technology: