Featured Research

from universities, journals, and other organizations

Slicing Chromosomes Leads To New Insights Into Cell Division

Date:
June 2, 2009
Source:
University of Michigan
Summary:
By using ultrafast laser pulses to slice off pieces of chromosomes and observe how the chromosomes behave, biomedical engineers have gained pivotal insights into mitosis, the process of cell division.

By using ultrafast laser pulses to slice off pieces of chromosomes and observe how the chromosomes behave, biomedical engineers at the University of Michigan have gained pivotal insights into mitosis, the process of cell division.

Related Articles


Their findings could help scientists better understand genetic diseases, aging and cancer.

Cells in plants, fungi, and animals—including those in the human body—divide through mitosis, during which the DNA-containing chromosomes separate between the resulting daughter cells. Forces in a structure called the mitotic spindle guide the replicated chromosomes to opposing sides as one cell eventually becomes two.

"Each cell needs the right number of chromosomes. It’s central to life in general and very important in terms of disease," said Alan Hunt, an associate professor in the Department of Biomedical Engineering and an author of a paper describing these findings published in Current Biology.

"One of the really important fundamental questions in biology is how do chromosomes get properly segregated when cells divide. What are the forces that move chromosomes around during this process? Where do they come from and what guides the movements?"

Hunt’s results validate the theory that "polar ejection forces" are at play. Scientists had hypothesized that the direction and magnitude of these forces might provide physical cues guiding chromosome movements. In this capacity, polar ejection forces would play a central role separating chromosomes in dividing cells, but no one had established a direct link until now.

Polar ejection forces are thought to arise out of the interaction between protein motors on the arms of chromosomes that push against cells’ microtubules. Microtubules are long, thin tubes that form a central component of the cytoskeleton and the mitotic spindle. They serve as intracellular structural supports and as railways along which molecular motors move cargoes such as chromosomes.

Hunt’s group hypothesized that polar ejection forces should be proportional to the chromosome’s size, and therefore could be predictably changed by altering the size of the chromosomes. Using newts as a model organism, they cut off pieces of the chromosomes’ arms.

"We asked what the relationship is between the size of the fragment we removed and the direction the chromosome moved," Hunt said. "Not only did we observe a relationship, we established that polar ejection forces were in fact a direct cue that guided chromosomal movements in mitosis."

To achieve this, Hunt performed "nanoscale surgery," as he calls it, taking advantage of the unprecedented precision of femtosecond pulses of laser light. A femtosecond is one billionth of one millionth of a second. The chromosomes he altered were only micrometers long, and the slices across the chromosomes were only nanometers thick. A nanometer is one-billionth of a meter, about a million times thinner than a human hair.

Understanding how chromosome guidance occurs allows scientists to determine how failures lead to genetic diseases, aging and cancer. When cells don’t properly divide, they usually die. But survival can cause cancer or aging-related disorders. Likewise, genetic diseases such as Down’s syndrome result from improper chromosome segregation.

Mitosis, Hunt says, is one of the most important targets of chemotherapy.

"By knowing how chromosomes move, we can better understand how these drugs interfere with those movements and we can design experiments to screen for new drugs," Hunt said. "It will also allow us to have a better handle on what makes these drugs work. There are a lot of drugs that interfere with mitosis, but only a few are good for cancer therapy."

This research is funded by the National Science Foundation, the National Institutes of Health and the Cellular Biotechnology Training Grant at the University of Michigan. Hunt is also an assistant research scientist in the U-M Institute of Gerontology, and director of the Biomedical Lab at the Center for Ultrafast Optical Sciences.


Story Source:

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


Journal Reference:

  1. Ke et al. The Distribution of Polar Ejection Forces Determines the Amplitude of Chromosome Directional Instability. Current Biology, 2009; 19 (10): 807 DOI: 10.1016/j.cub.2009.04.036

Cite This Page:

University of Michigan. "Slicing Chromosomes Leads To New Insights Into Cell Division." ScienceDaily. ScienceDaily, 2 June 2009. <www.sciencedaily.com/releases/2009/05/090529183252.htm>.
University of Michigan. (2009, June 2). Slicing Chromosomes Leads To New Insights Into Cell Division. ScienceDaily. Retrieved November 24, 2014 from www.sciencedaily.com/releases/2009/05/090529183252.htm
University of Michigan. "Slicing Chromosomes Leads To New Insights Into Cell Division." ScienceDaily. www.sciencedaily.com/releases/2009/05/090529183252.htm (accessed November 24, 2014).

Share This


More From ScienceDaily



More Plants & Animals News

Monday, November 24, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Ebola-Hit Sierra Leone's Late Cocoa Leaves Bitter Taste

Ebola-Hit Sierra Leone's Late Cocoa Leaves Bitter Taste

AFP (Nov. 23, 2014) The arable district of Kenema in Sierra Leone -- at the centre of the Ebola outbreak in May -- has been under quarantine for three months as the cocoa harvest comes in. Duration: 01:32 Video provided by AFP
Powered by NewsLook.com
Anglerfish Rarely Seen In Its Habitat Will Haunt You

Anglerfish Rarely Seen In Its Habitat Will Haunt You

Newsy (Nov. 22, 2014) For the first time Monterey Bay Aquarium recorded a video of the elusive, creepy and rarely seen anglerfish. Video provided by Newsy
Powered by NewsLook.com
Birds Around the World Take Flight

Birds Around the World Take Flight

Reuters - Light News Video Online (Nov. 22, 2014) An imperial eagle equipped with a camera spreads its wings over London. It's just one of the many birds making headlines in this week's "animal roundup". Jillian Kitchener reports. Video provided by Reuters
Powered by NewsLook.com
Could Your Genes Be The Reason You're Single?

Could Your Genes Be The Reason You're Single?

Newsy (Nov. 21, 2014) Researchers in Beijing discovered a gene called 5-HTA1, and carriers are reportedly 20 percent more likely to be single. Video provided by Newsy
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