Nanotechnology Now

Our NanoNews Digest Sponsors



Heifer International

Wikipedia Affiliate Button


android tablet pc

Home > Press > Rice physicists help unravel mystery of repetitive DNA segments

Abstract:
Scientists gather clues by measuring forces needed to stretch single strands of DNA

Rice physicists help unravel mystery of repetitive DNA segments

Houston, TX | Posted on December 8th, 2010

With new tools that can grab individual strands of DNA and stretch them like rubber bands, Rice University scientists are working to unravel a mystery of modern genomics. Their latest findings, which appear in Physical Review Letters, offer new clues about the physical makeup of odd segments of DNA that have just one DNA base, adenine, repeated dozens of times in a row.

These mysterious "poly(dA) repeats" are sprinkled throughout the human genome. Scientists have also found them in the genomes of animals, plants and other species over the past decade. But researchers do not know why they are there, what function they perform or why they occur only with the DNA base adenine and not the other three DNA bases -- cytosine, guanine and thymine.

"Previous investigations of poly(dA) have suggested that adenine bases stack in a very uniform way," said Ching-Hwa Kiang, a co-author of the new study and assistant professor of physics and astronomy at Rice. "Our investigation focused on what happens when single strands of poly(dA) were stretched and these stacks were pulled apart."

Kiang's research group specializes in studying the physical and mechanical properties of proteins and nucleic acids, and their primary tool is one of the mainstays of nanotechnology research -- the atomic force microscope, or AFM. The business end of an AFM is like a tiny phonograph needle. The tip of the needle is no more than a few atoms wide, and the needle is at the end of an arm that bobs up and down over the surface of what is being measured. While nanotechnologists use the device to measure the thickness of samples, Kiang's group uses it in a different way.

To begin her experiments, Kiang first places a thin coating of the proteins she wishes to study on a flat surface. This is placed under the AFM arm so the bobbing AFM needle can dip down and grab the ends of one of the proteins. As the arm retracts, it unravels the protein.

All proteins fold into a characteristic shape. Like tiny springs, they remain in this compact "lowest energy" state unless they are pried apart.

The new study on poly(dA) was conducted by Kiang, Rice graduate student Wuen-shiu Chen and colleagues at Rice and National Chung Hsing University (NCHU) in Taiwan. The team discovered that poly(dA) behaves differently depending upon the speed with which it is stretched. When the AFM bobbed rapidly, the poly(dA) segments behaved like any other segment of single-stranded DNA. But when the AFM motion was slowed, the team found that the amount of force required to stretch the poly(dA) changed. At two particular locations, the strand lengthened for a short distance without any additional force at all.

"Typically, single strands of DNA behave like a rubber band: The resistance increases as they stretch, meaning you have to pull harder and harder to continue stretching them," Kiang said. "With poly(dA), we found these two points where that doesn't apply. It's as if you have to pull harder and harder, and then for a brief time, the band stretches with no additional force whatsoever."

Kiang said the exact causes and implications of the phenomenon are unclear. But scientists know that double-stranded DNA must be pried apart at discrete locations so that the cell's machinery can read the genetic code and convert it into proteins. There has been some speculation that the adenine repeats play a role in ordering genomic information; Kiang said the new findings raise even more questions about the role the repeats might play in gene regulation and genome packaging and how they might be potential targets for cancer drugs.

The research was supported by the National Science Foundation, the Welch Foundation and the Rice Institute of Biosciences and Bioengineering's Hamill Innovation Fund. Study co-authors include Rice undergraduate students Zephan Chen and Ashton Gooding, exchange graduate student Wei-Hung Chen from NCHU and NCHU Professor of Chemistry Kuan-Jiuh Lin.

####

About Rice University
Located in Houston, Rice University is consistently ranked one of America's best teaching and research universities. Known for its "unconventional wisdom," Rice is distinguished by its: size -- 3,279 undergraduates and 2,277 graduate students; selectivity -- 12 applicants for each place in the freshman class; resources -- an undergraduate student-to-faculty ratio of 5-to-1; sixth largest endowment per student among American private research universities; residential college system, which builds communities that are both close-knit and diverse; and collaborative culture, which crosses disciplines, integrates teaching and research, and intermingles undergraduate and graduate work.

For more information, please click here

Contacts:
Jade Boyd
713-348-6778

Copyright © Rice University

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

News and information

New research project supports internationalisation in nano-research: Launch of new “Baltic Sea Network” November 22nd, 2014

3rd Iran-Proposed Nano Standard Approved by International Standard Organization November 22nd, 2014

NMTI announces breakthrough solutions for HAMR nanoantenna for next-generation ultra-high density magnetic storage November 21st, 2014

Canatu Launches CNB In-Mold Film for Transparent Touch on 3D Surfaces –in Cars, Household Appliances, Wearables, Portables November 20th, 2014

Govt.-Legislation/Regulation/Funding/Policy

New research project supports internationalisation in nano-research: Launch of new “Baltic Sea Network” November 22nd, 2014

3rd Iran-Proposed Nano Standard Approved by International Standard Organization November 22nd, 2014

NMTI announces breakthrough solutions for HAMR nanoantenna for next-generation ultra-high density magnetic storage November 21st, 2014

Quantum mechanical calculations reveal the hidden states of enzyme active sites November 20th, 2014

Academic/Education

SUNY Poly Student Awarded Fellowship with the U.S. Department of Energy's Postgraduate Research Program: Ph.D. Candidate Accepts Postmaster's Appointment To Conduct Research At Albany NanoTech Complex November 13th, 2014

SUNY Polytechnic Institute Hosts Massive Crowd of More Than 3,000 People Who Attended Community Day Activities Across New York State: CNSE’s ‘NANOvember’ kickoff event highlights New York State’s growing high-tech sector with open house events in Albany, Utica, and Rochester November 3rd, 2014

SUNY Polytechnic Institute Invites the Public to Attend its Popular Statewide 'NANOvember' Series of Outreach and Educational Events October 23rd, 2014

First Canada Excellence Research Chair gets $10 million from the federal government for oilsands research at the University of Calgary: Federal government announces prestigious research chair to study improving oil production efficiency October 19th, 2014

Nanomedicine

New research project supports internationalisation in nano-research: Launch of new “Baltic Sea Network” November 22nd, 2014

Quantum mechanical calculations reveal the hidden states of enzyme active sites November 20th, 2014

Silver Nanoparticles Produced in Iran from Forest Plants Extract November 20th, 2014

Tokyo Institute of Technology research: Protein-engineered cages aid studies of cell functions November 19th, 2014

Announcements

New research project supports internationalisation in nano-research: Launch of new “Baltic Sea Network” November 22nd, 2014

3rd Iran-Proposed Nano Standard Approved by International Standard Organization November 22nd, 2014

NMTI announces breakthrough solutions for HAMR nanoantenna for next-generation ultra-high density magnetic storage November 21st, 2014

Nano Sorbents Able to Remove Pollutions Caused by Oil Derivatives November 20th, 2014

Tools

Leica Microsystems Presents Universal Hybrid Detector for Single Molecule Detection and Imaging at SfN and ASCB: Leica HyD SMD - the Optimal Detector for Precise and Reliable SMD data November 20th, 2014

Nanometrics Announces Upcoming Investor Events November 19th, 2014

Two sensors in one: Nanoparticles that enable both MRI and fluorescent imaging could monitor cancer, other diseases November 18th, 2014

Field-emission plug-and-play solution for microwave electron guns: To simplify the electron emission mechanism involved in microwave electron guns, a team of researchers has created and demonstrated a field-emission plug-and-play solution based on ultrananocrystalline diamond November 18th, 2014

Nanobiotechnology

Quantum mechanical calculations reveal the hidden states of enzyme active sites November 20th, 2014

Tokyo Institute of Technology research: Protein-engineered cages aid studies of cell functions November 19th, 2014

A novel method for identifying the body’s ‘noisiest’ networks November 19th, 2014

Implementation of DNA Chains in Designing Nanospin Pieces November 9th, 2014

NanoNews-Digest
The latest news from around the world, FREE




  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More












ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project







© Copyright 1999-2014 7th Wave, Inc. All Rights Reserved PRIVACY POLICY :: CONTACT US :: STATS :: SITE MAP :: ADVERTISE