Navigation Links
Scientists find a fingerprint of evolution across the human genome
Date:4/8/2008

The Human Genome Project revealed that only a small fraction of the 3 billion letter DNA code actually instructs cells to manufacture proteins, the workhorses of most life processes. This has raised the question of what the remaining part of the human genome does. How much of the rest performs other biological functions, and how much is merely residue of prior genetic events"

Scientists from Cold Spring Harbor Laboratory (CSHL) and the University of Chicago now report that one of the steps in turning genetic information into proteins leaves genetic fingerprints, even on regions of the DNA that are not involved in coding for the final protein. They estimate that such fingerprints affect at least a third of the genome, suggesting that while most DNA does not code for proteins, much of it is nonetheless biologically important important enough, that is, to persist during evolution.

Conservation of genetic information

To gauge how critical a particular stretch of DNA is, biologists often look at the detailed sequence of letters it consists of, and compare it with a corresponding stretch in related creatures like mice. If the stretch serves no purpose, the thinking goes, the two sequences will differ because of numerous mutations since the two species last shared an ancestor. In contrast, its believed that the sequences of important genes will be similar, or conserved, in different species, because animals with mutations in these genes did not survive. Biologists therefore regard conserved sequences as a sign of biological importance.

To test for conservation, researchers need to find matching stretches in the two species. This is relatively easy for stretches that code for proteins, where scientists long ago learned the meaning of the sequence. For noncoding regions, however, the comparison is often ambiguous. Even within a gene, stretches of DNA that code for pieces of the target protein are usually interspersed with much larger noncoding stretches, called introns, that are removed from the RNA working copy of the DNA before the protein is made.

Signs of splicing

Previous researchers assumed that mutations in the middle of introns do not affect the final protein, so they simply accumulate. In the new work, however, the researchers found signs that evolution rejects some types of mutations even in these regions of the genome. Although the selection is weak, introns are not neutral, in their effect on survival, says CSHL professor Michael Zhang, a bioinformatics expert who headed the research team.

To look for selection, CSHL researcher Chaolin Zhang, a doctoral candidate at Stony Brook University, looked in the human genome for a subtle statistical imbalance in how often various letters appear. The researchers attribute this imbalance to special short stretches of DNA that mark regions to be removed. Unless these signal sequences are sprinkled throughout an intron, the data suggest, it may not be properly spliced out, with potentially fatal consequences. Other sequences must likewise be preserved in the regions to be retained.

The scientists found a preference for some letters across intron regions, and the opposite preference in coding regions. Together, these regions make up at least a third of the genome, which is thus under selective pressure during evolution. The result supports other recent studies that suggest that, although most DNA does not code for proteins, much of it is nonetheless biologically important.

In addition to demonstrating how splicing affects genetic evolution, the statistical analysis identified possible signaling sequences, some that were already known and others that are new. According to co-author Adrian Krainer, a CSHL professor and splicing expert, the exciting thing will be to experimentally test whether these predicted elements are really true.


'/>"/>

Contact: Jim Bono
bono@cshl.edu
516-367-8455
Cold Spring Harbor Laboratory
Source:Eurekalert

Related biology news :

1. Death protein research secures funding for UCF scientists
2. Yale scientists visualize the machinery of mRNA splicing
3. Cold Spring Harbor Laboratory scientists devise potential approach to treat spinal muscular atrophy
4. Scientists discover 356 animal inclusions trapped in 100 million years old opaque amber
5. Great Ape Trust to gather internationally recognized scientists for Decade of the Mind III
6. CSHL scientists part of team that discovers role of rare gene mutations in schizophrenia
7. CSHL scientists identify a mechanism that helps fruit flies lock-in memories
8. Scientists find that squid beak is both hard and soft, a material that engineers want to copy
9. Scientists launch first comprehensive database of human oral microbiome
10. NYU scientists set stage for understanding how color vision is processed
11. Scientists launch human oral microbiome database
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:6/22/2016)... , June 22, 2016 On Monday, ... call to industry to share solutions for the Biometric ... U.S. Customs and Border Protection (CBP), explains that CBP ... are departing the United States , ... and to defeat imposters. Logo - ...
(Date:6/9/2016)... June 9, 2016  Perkotek an innovation leader in attendance control systems is proud ... work hours, for employers to make sure the right employees are actually signing in, ... ... ... ...
(Date:6/2/2016)...   The Weather Company , an IBM Business (NYSE: ... capability in which consumers will be able to interact with ... via voice or text and receive relevant information about the ... Marketers have long sought an advertising solution that can create ... relevant and valuable; and can scale across millions of interactions ...
Breaking Biology News(10 mins):
(Date:6/23/2016)... ... June 23, 2016 , ... Supplyframe, the Industry Network for ... Design Lab . Located in Pasadena, Calif., the Design Lab’s mission is to ... are designed, built and brought to market. , The Design Lab is Supplyframe’s ...
(Date:6/23/2016)... Durham, NC (PRWEB) , ... June 23, 2016 , ... ... Odense University Hospital in Denmark detail how a patient who developed lymphedema after being ... (fat) tissue. The results could change the paradigm for dealing with this debilitating, frequent ...
(Date:6/23/2016)... Calif. , June 23, 2016  Blueprint Bio, ... biological discoveries to the medical community, has closed its ... Matthew Nunez . "We have received ... with the capital we need to meet our current ... essentially provide us the runway to complete validation on ...
(Date:6/23/2016)... On Wednesday, June 22, 2016, the ... the Dow Jones Industrial Average edged 0.27% lower to finish ... 0.17%. Stock-Callers.com has initiated coverage on the following equities: Infinity ... NKTR ), Aralez Pharmaceuticals Inc. (NASDAQ: ... ). Learn more about these stocks by accessing their free ...
Breaking Biology Technology: