Featured Research

from universities, journals, and other organizations

A Solution To Darwin's 'Mystery Of The Mysteries' Emerges From The Dark Matter Of The Genome

Date:
November 1, 2009
Source:
Fred Hutchinson Cancer Research Center
Summary:
Why do crosses between two species often yield sterile or inviable progeny (for instance, mules emerging from a cross between a horse and a donkey)? New research suggests that the solution to this problem lies in the "dark matter of the genome": heterochromatin, a tightly packed, gene-poor compartment of DNA found within the genomes of all nucleated cells.

A mule (cross between a horse and a donkey).
Credit: iStockphoto/Michael Klenetsky

Biological species are often defined on the basis of reproductive isolation. Ever since Darwin pointed out his difficulty in explaining why crosses between two species often yield sterile or inviable progeny (for instance, mules emerging from a cross between a horse and a donkey), biologists have struggled with this question. New research into this field by basic scientists at Fred Hutchinson Cancer Research Center, published online Oct. 22 in Science Express, suggests that the solution to this problem lies within the "dark matter of the genome": heterochromatin, a tightly packed, gene-poor compartment of DNA found within the genomes of all nucleated cells.

Related Articles


"Speciation is one of the most fascinating, unsolved problems in biology," said Harmit Malik, Ph.D., an associate member of the Hutchinson Center's Basic Sciences Division and corresponding author of the paper.

Malik and first author Joshua Bayes, Ph.D., a former graduate student in the Malik lab, focused on understanding the cellular function of a particular fruit fly (Drosophila) gene dubbed Odysseus. The gene is so named because of its ability to cause havoc and male sterility when introduced into the genome of another species. Odysseus is a gene that is derived from a transcription factor, and it was long believed to be a protein that turned on expression of other genes in Drosophila testis.

Odysseus also had been previously shown to rapidly evolve in its DNA-binding domain. Based on this observation, Bayes and Malik reasoned that Odysseus must interact with some rapidly evolving DNA in the genome. They tested the hypothesis, first proposed by Malik and Hutchinson Center colleague Steven Henikoff, Ph.D., that such hybrid-sterility proteins may bind repetitive satellite DNA in heterochromatin. Such repeats are believed to evolve rapidly due to an "arms-race" for preferential transmission during the process of forming an egg, whereby only one of four chromosomes is non-randomly chosen to be included into the egg.

Consistent with this hypothesis, Bayes found that Odysseus proteins localize to heterochromatic DNA found next to centromeres and on gene-poor chromosomes, which leads to their decondensation. Dramatically, the hybrid-sterility-associated Odysseus from one species showed additional localization to the Y chromosome of the other species. Through experiments in cell lines and transgenic flies, Bayes further showed that Odysseus localization has rapidly evolved during recent evolution, evidence of the "arms-race" that drives rapid evolution of satellite DNA repeats. Altered expression and localization has profoundly deleterious consequences for the process of sperm formation, a process that remains a mystery and is under active study in the Malik lab.

The finding that rapidly evolving heterochromatin may underlie this phenomenon also ties in with other work in Malik's lab that explores how "mismatches" originating from rapid evolution of DNA and proteins could lead to chromosome segregation defects and aneuploidy events that are sometimes precursors in transitions to cancer.

Grants from the National Institutes of Health, the Mathers Foundation and the Howard Hughes Medical Institute funded this research.


Story Source:

The above story is based on materials provided by Fred Hutchinson Cancer Research Center. Note: Materials may be edited for content and length.


Cite This Page:

Fred Hutchinson Cancer Research Center. "A Solution To Darwin's 'Mystery Of The Mysteries' Emerges From The Dark Matter Of The Genome." ScienceDaily. ScienceDaily, 1 November 2009. <www.sciencedaily.com/releases/2009/10/091026152816.htm>.
Fred Hutchinson Cancer Research Center. (2009, November 1). A Solution To Darwin's 'Mystery Of The Mysteries' Emerges From The Dark Matter Of The Genome. ScienceDaily. Retrieved November 26, 2014 from www.sciencedaily.com/releases/2009/10/091026152816.htm
Fred Hutchinson Cancer Research Center. "A Solution To Darwin's 'Mystery Of The Mysteries' Emerges From The Dark Matter Of The Genome." ScienceDaily. www.sciencedaily.com/releases/2009/10/091026152816.htm (accessed November 26, 2014).

Share This


More From ScienceDaily



More Fossils & Ruins News

Wednesday, November 26, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Classic Hollywood Memorabilia Goes Under the Hammer

Classic Hollywood Memorabilia Goes Under the Hammer

Reuters - Entertainment Video Online (Nov. 26, 2014) The iconic piano from "Casablanca" and the Cowardly Lion suit from "The Wizard of Oz" fetch millions at auction. Sara Hemrajani reports. Video provided by Reuters
Powered by NewsLook.com
3D Map of Antarctic Sea Ice to Shed Light on Climate Change

3D Map of Antarctic Sea Ice to Shed Light on Climate Change

Reuters - Innovations Video Online (Nov. 24, 2014) A multinational group of scientists have released the first ever detailed, high-resolution 3-D maps of Antarctic sea ice. Using an underwater robot equipped with sonar, the researchers mapped the underside of a massive area of sea ice to gauge the impact of climate change. Ben Gruber reports. Video provided by Reuters
Powered by NewsLook.com
Ruins Thought To Be Port Actually Buried Greek City

Ruins Thought To Be Port Actually Buried Greek City

Newsy (Nov. 24, 2014) Media is calling it an "underwater Pompeii." Researchers have found ruins off the coast of Delos. Video provided by Newsy
Powered by NewsLook.com
Amphipolis Tomb Architraves Reveal Faces

Amphipolis Tomb Architraves Reveal Faces

AFP (Nov. 22, 2014) Faces in an area of mosaics is the latest find by archaeologists at a recently discovered tomb dating back to fourth century BC and the time of Alexander the Great in Greece. Duration: 01:05 Video provided by AFP
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:

Strange & Offbeat Stories


Plants & Animals

Earth & Climate

Fossils & Ruins

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