Featured Research

from universities, journals, and other organizations

Scientists map hotspots for genetic exchange in chimpanzees

Date:
March 15, 2012
Source:
Wellcome Trust
Summary:
Scientists have constructed the world's first genetic map in chimpanzees of recombination -- the exchange of genetic material within a chromosome that makes us all unique. The study shows surprising differences compared to how the process occurs in the human genome.

Chimpanzees. Scientists have constructed the world's first genetic map in chimpanzees of recombination -- the exchange of genetic material within a chromosome that makes us all unique.
Credit: Eric Gevaert / Fotolia

Scientists at the University of Oxford and the University of Chicago have constructed the world's first genetic map in chimpanzees of recombination -- the exchange of genetic material within a chromosome that makes us all unique. The study, published March 15 in Science Express, shows surprising differences compared to how the process occurs in the human genome.

Recombination is a biological process that shuffles parental DNA during the production of sperm and eggs. This fundamental process is shared by almost every form of life -- without shuffling, we would all be genetically identical. Natural selection operates on this diversity to drive the 'survival of the fittest', selecting advantageous genetic profiles.

The project to investigate how recombination has evolved in recent human and primate history was led by Professors Gil McVean, and Peter Donnelly from the Wellcome Trust Centre for Human Genetics at the University of Oxford, and Dr Molly Przeworski from the Howard Hughes Medical Institute. To study this evolution, they sequenced the entire genomes of ten western chimpanzees and identified differences between their DNA sequences.

The researchers observed that in the chimpanzee genome, for every one thousand bases -- the molecules identified by the letters A, C, G and T in DNA -- around one base was different. By analysing these DNA differences, they were able to map where recombination events had shuffled genetic material in the chimpanzees' ancestors and to compare this map to patterns of recombination in humans from other studies.

In a previous study, the researchers, together with Dr Simon Myers from the University of Oxford, had shown that in both chimpanzees and humans, recombination only occurs at specific locations of the genome, known as 'recombination hotspots'. Around 40% of these hotspots occur where a particular thirteen letter sequence of DNA is present.

In this new study, funded by the Wellcome Trust and the National Institutes of Health, the researchers found that there was no overlap in the location of recombination hotspots between humans and chimpanzees. This was an extraordinarily unexpected finding given the 98.5 per cent similarity between the human and chimpanzee genomes and extensive similarities at the cellular and organism level.

Professor McVean explains: "Genetic recombination has been likened to shuffling a deck of cards, which ensures that children are given a different genetic 'hand' than their parents. We know that in many cases recombination occurs where a particular thirteen letter sequence is present -- this is like a run of hearts from ace to king determining where we cut the deck of cards. Because humans and chimpanzees are genetically very similar, we might explain that you can only 'cut the cards' at the same point -- in fact, we find that this is not true."

Recent research found that a protein called PRDM9 binds to the 13 letter DNA motif; this protein is thought to play a central role in identifying where recombination events can occur in humans and other species. However, the gene that produces this protein differs significantly between humans and chimpanzees, and even within chimpanzees. The researchers believe this may explain the lack of overlap -- the difference in the PRDM9 gene is likely to lead to the proteins targeting different locations for recombination within the chimpanzee and human genomes.

Professor Donnelly says: "This is an exciting difference between humans and chimpanzees. PRDM9 is potentially one of the fastest evolving genes since humans split from chimpanzees 6.5 million years ago. It supports studies which suggest that the gene somehow determines where recombination occurs."

PRDM9 has been linked previously to speciation in mice -- two similar animals are defined as separate species if they are unable to mate together to produce viable offspring. When the gene was switched off in mice, they were rendered infertile.

Even though the recombination hotspots differ in location between humans and chimpanzees, the rate of recombination events is similar in humans and chimpanzees. However, the process has been disrupted where chromosomes have undergone major rearrangements in evolution -- for example, the human chromosome 2 is a fusion of two separate chimpanzee chromosomes, and this affects the rate of recombination events at this part of the genome.

Oliver Venn, a Wellcome Trust DPhil student at the University of Oxford, adds: "This is the first genome-wide study of genetic variation in our closest living relatives. Whilst, the aim of the research is to improve our understanding of recombination and how it has evolved, it may well tell us something about how and why new species arise."


Story Source:

The above story is based on materials provided by Wellcome Trust. Note: Materials may be edited for content and length.


Journal Reference:

  1. A. Auton, A. Fledel-Alon, S. Pfeifer, O. Venn, L. Segurel, T. Street, E. M. Leffler, R. Bowden, I. Aneas, J. Broxholme, P. Humburg, Z. Iqbal, G. Lunter, J. Maller, R. D. Hernandez, C. Melton, A. Venkat, M. A. Nobrega, R. Bontrop, S. Myers, P. Donnelly, M. Przeworski, G. McVean. A Fine-Scale Chimpanzee Genetic Map from Population Sequencing. Science, 2012; DOI: 10.1126/science.1216872

Cite This Page:

Wellcome Trust. "Scientists map hotspots for genetic exchange in chimpanzees." ScienceDaily. ScienceDaily, 15 March 2012. <www.sciencedaily.com/releases/2012/03/120315145413.htm>.
Wellcome Trust. (2012, March 15). Scientists map hotspots for genetic exchange in chimpanzees. ScienceDaily. Retrieved July 29, 2014 from www.sciencedaily.com/releases/2012/03/120315145413.htm
Wellcome Trust. "Scientists map hotspots for genetic exchange in chimpanzees." ScienceDaily. www.sciencedaily.com/releases/2012/03/120315145413.htm (accessed July 29, 2014).

Share This




More Plants & Animals News

Tuesday, July 29, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Deadly Ebola Virus Threatens West Africa

Deadly Ebola Virus Threatens West Africa

AP (July 28, 2014) West African nations and international health organizations are working to contain the largest Ebola outbreak in history. It's one of the deadliest diseases known to man, but the CDC says it's unlikely to spread in the U.S. (July 28) Video provided by AP
Powered by NewsLook.com
Traditional African Dishes Teach Healthy Eating

Traditional African Dishes Teach Healthy Eating

AP (July 28, 2014) Classes are being offered nationwide to encourage African Americans to learn about cooking fresh foods based on traditional African cuisine. The program is trying to combat obesity, heart disease and other ailments often linked to diet. (July 28) Video provided by AP
Powered by NewsLook.com
Asteroid's Timing Was 'Colossal Bad Luck' For The Dinosaurs

Asteroid's Timing Was 'Colossal Bad Luck' For The Dinosaurs

Newsy (July 28, 2014) The asteroid that killed the dinosaurs struck at the worst time for them. A new study says that if it hit earlier or later, they might've survived. Video provided by Newsy
Powered by NewsLook.com
Raw: Sea Turtle Hatchlings Emerge from Nest

Raw: Sea Turtle Hatchlings Emerge from Nest

AP (July 27, 2014) A live-streaming webcam catches loggerhead sea turtle hatchlings emerging from a nest in the Florida Keys. (July 27) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins