Genomic hitchhikers in birds shed light on evolution of viruses

October 16, 2012

The genomes of birds are riddled with DNA sequences from viruses, according to a study to be published on October 16 in mBio®, the online open-access journal of the American Society for Microbiology. Analysis of these viral sequences, known as endogenous retroviruses (ERVs), can provide insights into how both hosts and viruses have evolved over the eons.

"We examined the evolution of avian retroviruses on the basis of their fossil remnants in the three avian genomes that have been completely sequenced," write the authors from Johns Hopkins University and Uppsala University, Sweden. The authors go on to say their analyses of ERVs in chicken, turkey, and zebra finch genomes reveal that birds were a hotbed of viral evolution early in their history.

All genomes are cobbled together works-in-progress. Scientists have long known that the human genome, for example, is not all human: like most every other genome studied to date, a good chunk of the DNA we call "human" is actually made up of proviruses, sequences that retroviruses have deposited there to take advantage of the cell's ability to copy DNA and translate that DNA into working proteins. These proviruses can either be inherited in the DNA we get from our parents (endogenous retroviruses), or they can be picked up during our lifetime (exogenous retroviruses).

The study reveals that millions of years ago birds were host to many different kinds of ERVs, serving as a kind of melting pot: a meeting and mingling place where viruses recombined and shared genetic information.

Unlike early studies of ERVs in chickens, which studied selected segments of the genome and uncovered only alpha-retroviruses, this study used complete genome sequences and found a great diversity of viral sequences in bird genomes, representing the same major groups as those of mammals, but exhibiting more diversity. Most of the ERVs in birds were distinct from those found in other animals, probably indicating that the viruses did not move much between different kinds of hosts.

"We conclude that avian retroviral evolution differs from that of other vertebrates," write the researchers. "Avian retroviruses seem to have evolved rather independently from the rest of the retroviruses over the last 150 million years."

Stepher Goff of Columbia University, who was not involved in the research but edited the article for mBio®, says genome-level studies like this are a boon to virologists.

"This paper is filling a big gap in our understanding of these viruses," says Goff. "This is something that needed to be done, and advancing sequencing technology made it easy to do."
-end-
mBio® is an open access online journal published by the American Society for Microbiology to make microbiology research broadly accessible. The focus of the journal is on rapid publication of cutting-edge research spanning the entire spectrum of microbiology and related fields. It can be found online at http://mBio.asm.org.

The American Society for Microbiology is the largest single life science society, composed of over 39,000 scientists and health professionals. ASM's mission is to advance the microbiological sciences as a vehicle for understanding life processes and to apply and communicate this knowledge for the improvement of health and environmental and economic well-being worldwide.

American Society for Microbiology

Related DNA Articles from Brightsurf:

A new twist on DNA origami
A team* of scientists from ASU and Shanghai Jiao Tong University (SJTU) led by Hao Yan, ASU's Milton Glick Professor in the School of Molecular Sciences, and director of the ASU Biodesign Institute's Center for Molecular Design and Biomimetics, has just announced the creation of a new type of meta-DNA structures that will open up the fields of optoelectronics (including information storage and encryption) as well as synthetic biology.

Solving a DNA mystery
''A watched pot never boils,'' as the saying goes, but that was not the case for UC Santa Barbara researchers watching a ''pot'' of liquids formed from DNA.

Junk DNA might be really, really useful for biocomputing
When you don't understand how things work, it's not unusual to think of them as just plain old junk.

Designing DNA from scratch: Engineering the functions of micrometer-sized DNA droplets
Scientists at Tokyo Institute of Technology (Tokyo Tech) have constructed ''DNA droplets'' comprising designed DNA nanostructures.

Does DNA in the water tell us how many fish are there?
Researchers have developed a new non-invasive method to count individual fish by measuring the concentration of environmental DNA in the water, which could be applied for quantitative monitoring of aquatic ecosystems.

Zigzag DNA
How the cell organizes DNA into tightly packed chromosomes. Nature publication by Delft University of Technology and EMBL Heidelberg.

Scientists now know what DNA's chaperone looks like
Researchers have discovered the structure of the FACT protein -- a mysterious protein central to the functioning of DNA.

DNA is like everything else: it's not what you have, but how you use it
A new paradigm for reading out genetic information in DNA is described by Dr.

A new spin on DNA
For decades, researchers have chased ways to study biological machines.

From face to DNA: New method aims to improve match between DNA sample and face database
Predicting what someone's face looks like based on a DNA sample remains a hard nut to crack for science.

Read More: DNA News and DNA Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.