Featured Research

from universities, journals, and other organizations

Free Radicals And Fertilization: Study Reveals Egg Protection Secret

Date:
December 16, 2004
Source:
Brown University
Summary:
Sea urchin eggs, a common model for human fertility research, create a protein shield just minutes after fertilization. In Developmental Cell, Brown University biologists reveal their discovery of an enzyme that generates hydrogen peroxide, a free radical critical to this protective process. The finding illuminates a survival mechanism shared across species.

Strongylocentrotus purpuratus: the purple sea urchin.
Credit: Photo courtesy of Brown University

PROVIDENCE, R.I. — Brown University researchers have discovered an enzyme that produces hydrogen peroxide in the fertilized eggs of sea urchins. This infection-fighting free radical helps create a barrier around the egg, keeping out invading sperm, harmful bacteria and other destructive forces.

Their finding, published in the current issue of Developmental Cell, solves a century-old biology riddle. In most animals, such as sea urchins, fish, mice and humans, only one sperm fertilizes an egg. If multiple sperm fuse with the egg, a process known as polyspermy, the embryo will die. So the fertilized egg quickly creates protective barriers. Scientists have known for more than 30 years that, in sea urchins, hydrogen peroxide is a key player in this process. Until now, they did not know how that potentially toxic substance was produced or controlled.

Julian Wong, a Brown research associate and lead researcher on the project, set out to find the gene responsible for pumping out this peroxide. In the Sea Urchin Genome Project database, Wong found a gene that he suspected was key for this process because it looked similar to one that produces peroxide in the human thyroid.

After a series of experiments using sea urchins, Wong found that his guess was correct. While the egg matures, this gene is turned on and creates an enzyme known as urchin dual oxidase, or Udx1. Immediately after fertilization, Udx1 is activated to produce peroxide. The peroxide is then used to “stitch” together proteins on a thin layer surrounding the egg, hardening it into a tough coating. The process is complete about five minutes after fertilization.

Wong showed this essential role by obstructing the function of Udx1. When its activity was blocked, the protective barrier didn’t harden, leaving the embryo vulnerable.

The authors were surprised by the results. “The best model we had was in white blood cells, which use a similar burst of hydrogen peroxide to kill bacteria,” Wong said. “So we always thought that the mechanism would be similar. But what happens in the egg is more like what happens in the thyroid, suggesting that this Udx1 mechanism is versatile and non-lethal.”

“Nature is thrifty,” said Gary Wessel, senior scientist on the project and professor of biology in the Department of Molecular Biology, Cell Biology and Biochemistry. “Cells can take one process, adapt it, and use it in completely different ways.”

Wessel said that human eggs also create a barrier against polyspermy after fertilization. While the production of peroxide in this process hasn’t been proven in humans, Wessel said scientists suspect a similar process occurs. If true, a damaged or missing peroxide-producing gene could explain one source of infertility.

Wessel said their finding also sheds light on the contributions of free radicals to reproductive biology. Typically, free radicals damage cells. But Wessel said these molecules can also be helpful, killing germs, reducing high blood pressure or, in this case, protecting fertilized eggs.

Robbert Crιton, assistant professor of biology, also participated in the study. The National Institutes of Health and the National Science Foundation funded the work.


Story Source:

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


Cite This Page:

Brown University. "Free Radicals And Fertilization: Study Reveals Egg Protection Secret." ScienceDaily. ScienceDaily, 16 December 2004. <www.sciencedaily.com/releases/2004/12/041206202914.htm>.
Brown University. (2004, December 16). Free Radicals And Fertilization: Study Reveals Egg Protection Secret. ScienceDaily. Retrieved July 24, 2014 from www.sciencedaily.com/releases/2004/12/041206202914.htm
Brown University. "Free Radicals And Fertilization: Study Reveals Egg Protection Secret." ScienceDaily. www.sciencedaily.com/releases/2004/12/041206202914.htm (accessed July 24, 2014).

Share This




More Plants & Animals News

Thursday, July 24, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Stone Fruit Listeria Scare Causes Sweeping Recall

Stone Fruit Listeria Scare Causes Sweeping Recall

Newsy (July 22, 2014) — The Wawona Packing Company has issued a voluntary recall on the stone fruit it distributes due to a possible Listeria outbreak. Video provided by Newsy
Powered by NewsLook.com
Michigan Plant's Goal: Flower and Die

Michigan Plant's Goal: Flower and Die

AP (July 22, 2014) — An 80-year-old agave plant, which is blooming for the first and only time at a University of Michigan conservatory, will die when it's done (July 22) Video provided by AP
Powered by NewsLook.com
Huge Schizophrenia Study Finds Dozens Of New Genetic Causes

Huge Schizophrenia Study Finds Dozens Of New Genetic Causes

Newsy (July 22, 2014) — The 83 new genetic markers could open dozens of new avenues for schizophrenia treatment research. Video provided by Newsy
Powered by NewsLook.com
CDC Head Concerned About a Post-Antibiotic Era

CDC Head Concerned About a Post-Antibiotic Era

AP (July 22, 2014) — Sounding alarms about the growing threat of antibiotic resistance, CDC Director Tom Frieden warned Tuesday if the global community does not confront the problem soon, the world will be living in a devastating post-antibiotic era. (July 22) 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