Navigation Links
A 'jumping gene's' preferred targets may influence genome evolution
Date:9/6/2011

Baltimore, MD The human genome shares several peculiarities with the DNA of just about every other plant and animal. Our genetic blueprint contains numerous entities known as transposons, or "jumping genes," which have the ability to move from place to place on the chromosomes within a cell.

An astounding 50% of human DNA comprises both active transposon elements and the decaying remains of former transposons that were active thousands to millions of years ago before becoming damaged and immobile. If all of this mobile and formerly mobile DNA were not mysterious enough, every time a plant, animal or human cell prepares to divide, the chromosome regions richest in transposon-derived sequences, even elements long deceased, are among the last to duplicate. The reason for their delayed duplication, if there is one, has eluded biologists for more than 50 years.

New research led by Carnegie's Allan Spradling and published online this week by Proceedings of the National Academy of Sciences provides potential insight into both these enigmas.

The scientists used the fruit fly, Drosophila melanogaster, one of the premier "model" organisms for studying genome structure and gene function. They focused on one particular transposon, called the P element, which has an unsurpassed ability to move that has stimulated its widespread use by Drosophila researchers.

Remarkably, P elements have only been present in Drosophila melanogaster for about 80 years, at which time they were acquired from the genome of a distantly related fruit fly species by an unknown process. P elements remain highly "infective" today. Adding just one copy to the genome of one fly causes all the flies in a laboratory population with which it breeds to acquire 30 to 50 P elements within a few generations. The original goal of the Spradling team's research was not to understand how transposons spread or genomes evolve, but something much simpler: To learn why P elements insert at some locations in the genome but not in others.

Spradling and his colleagues, who oversee the NIH-funded Drosophila "Gene Disruption Project" used a database containing more than 50,000 genomic sites where P elements have inserted. They built this exceptional database over the last 20 years.

P elements insert into DNA very selectively. Nearly 40% of new jumps occur within just 300 genes and always near the beginning of the gene. But the genes seemed to have nothing in common. When these sites were compared to data about the Drosophila genome, particularly recent studies of Drosophila genome duplication, the answer became clear. What many P insertion sites share in common is an ability to function as starting sites or "origins" for DNA duplication. This association between P elements and the machinery of genome duplication suggested that they can coordinate their movement with DNA replication.

Spradling and his team propose that P elementsand likely other transposons as welluse a replication connection to spread more rapidly through genomes. These elements would only transpose after replicating, and then preferentially insert themselves into portions of DNA that have not yet become activated. This would allow them to duplicate twice rather than just once during the genome duplication cycle.

If the elements get a late start, however, only the last segments of the chromosome to duplicate will be left for their second duplication. This explains tendency of such regions to be transposon-rich. However, the researchers found that two other Drosophila transposons, known as piggyBac and Minos, do not insert at replication origins, so this mechanism is far from universal. Furthermore, Spradling cautioned that it is particularly difficult to experimentally test hypotheses about evolution.

"By gaining insight into one specific transposon's movements, we may have begun to glimpse mechanisms that have profoundly influenced genome evolution for nearly all animals" Spradling commented.


'/>"/>

Contact: Allan Spradling
spradling@ciwemb.edu
410-246-3021
Carnegie Institution
Source:Eurekalert

Related biology news :

1. The informant: a jumping gene
2. David and Goliath viruses shed light on the origin of jumping genes: UBC study
3. Discovery of jumping gene cluster tangles tree of life
4. Johns Hopkins researchers capture jumping genes
5. Jumping genes find new homes in humans more often than previously thought
6. Jumping genes provide extensive raw material for evolution, Penn study finds
7. The genetic secrets to jumping the species barrier
8. New data suggest jumping genes play a significant role in gene regulatory networks
9. McMaster researchers find missing genes may separate coach potato from active cousin
10. Parents stress leaves lasting marks on children’s genes: UBC-CFRI research
11. How an evolutionary playground brings plant genes together
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:6/14/2017)... (NYSE: IBM ) is introducing several innovative partner startups ... collaboration between startups and global businesses, taking place in ... nine startups will showcase the solutions they have built with ... France is one of the ... percent increase in the number of startups created between 2012 ...
(Date:5/16/2017)... 16, 2017   Bridge Patient Portal , ... MD EMR Systems , an electronic medical ... GE, have established a partnership to build an ... the GE Centricity™ products, including Centricity Practice Solution ... These new integrations will allow healthcare delivery ...
(Date:4/19/2017)... ALBANY, New York , April 19, 2017 /PRNewswire/ ... highly competitive, as its vendor landscape is marked by ... in the market is however held by five major ... and Safran. Together these companies accounted for nearly 61% ... majority of the leading companies in the global military ...
Breaking Biology News(10 mins):
(Date:10/10/2017)... , ... October 10, 2017 , ... ... Center’s FirstHand program has won a US2020 STEM Mentoring Award. Representatives of the ... for Excellence in Volunteer Experience from US2020. , US2020’s mission is to change ...
(Date:10/10/2017)... ... 10, 2017 , ... The Pittcon Program Committee is pleased ... scientists who have made outstanding contributions to analytical chemistry and applied spectroscopy. Each ... leading conference and exposition for laboratory science, which will be held February 26-March ...
(Date:10/9/2017)... ... October 09, 2017 , ... ... journal, Epilepsia, Brain Sentinel’s SPEAC® System which uses the surface electromyography (sEMG) ... tonic-clonic seizures (GTCS) using surface electromyography (sEMG). The prospective multicenter phase III ...
(Date:10/6/2017)... ... October 06, 2017 , ... On Tuesday, October ... on INSIGhT, the first-ever adaptive clinical trial for glioblastoma (GBM). The featured speaker ... is free and open to the public, but registration is required. , WHAT: ...
Breaking Biology Technology: