Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button


DHgate

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

Chemical cages: New technique advances synthetic biology February 10th, 2016

New thin film transistor may lead to flexible devices: Researchers engineer an electronics first, opening door to flexible electronics February 10th, 2016

Making sense of metallic glass February 9th, 2016

Electron's 1-D metallic surface state observed: A step for the prediction of electronic properties of extremely-fine metal nanowires in next-generation semiconductors February 9th, 2016

Govt.-Legislation/Regulation/Funding/Policy

New thin film transistor may lead to flexible devices: Researchers engineer an electronics first, opening door to flexible electronics February 10th, 2016

SUNY Poly and GLOBALFOUNDRIES Announce New $500M R&D Program in Albany To Accelerate Next Generation Chip Technology: Arrival of Second Cutting Edge EUV Lithography Tool Launches New Patterning Center That Will Generate Over 100 New High Tech Jobs at SUNY Poly February 9th, 2016

Making sense of metallic glass February 9th, 2016

Nanoparticle therapy that uses LDL and fish oil kills liver cancer cells February 9th, 2016

Academic/Education

SUNY Poly and GLOBALFOUNDRIES Announce New $500M R&D Program in Albany To Accelerate Next Generation Chip Technology: Arrival of Second Cutting Edge EUV Lithography Tool Launches New Patterning Center That Will Generate Over 100 New High Tech Jobs at SUNY Poly February 9th, 2016

COD Grad Begins Postdoctoral Fellow at Harvard University: Marsela Jorgolli's Passion for Physics Has Led to a Decade of Academic Research That Continues at Harvard University as a Postdoctoral Fellow February 2nd, 2016

Heriot-Watt's Institute of Photonics & Quantum Sciences uses the Deben Microtest 2 kN tensile stage to characterise ceramics and engineering plastics January 21st, 2016

Multiple uses for the JPK NanoWizard AFM system in the Smart Interfaces in Environmental Nanotechnology Group at the University of Illinois at Urbana-Champaign January 20th, 2016

Nanomedicine

Nanoparticle therapy that uses LDL and fish oil kills liver cancer cells February 9th, 2016

Leading bugs to the death chamber: A kinder face of cholesterol February 8th, 2016

UTHealth research looks at nanotechnology to help prevent preterm birth February 7th, 2016

Scientists take key step toward custom-made nanoscale chemical factories: Berkeley Lab researchers part of team that creates new function in tiny protein shell structures February 6th, 2016

Announcements

Chemical cages: New technique advances synthetic biology February 10th, 2016

New thin film transistor may lead to flexible devices: Researchers engineer an electronics first, opening door to flexible electronics February 10th, 2016

Superconductivity: Footballs with no resistance - Indications of light-induced lossless electricity transmission in fullerenes contribute to the search for superconducting materials for practical applications February 9th, 2016

SUNY Poly and GLOBALFOUNDRIES Announce New $500M R&D Program in Albany To Accelerate Next Generation Chip Technology: Arrival of Second Cutting Edge EUV Lithography Tool Launches New Patterning Center That Will Generate Over 100 New High Tech Jobs at SUNY Poly February 9th, 2016

Tools

Making sense of metallic glass February 9th, 2016

Chiral magnetic effect generates quantum current: Separating left- and right-handed particles in a semi-metallic material produces anomalously high conductivity February 8th, 2016

Metal oxide sandwiches: New option to manipulate properties of interfaces February 8th, 2016

Researchers discover new phase of boron nitride and a new way to create pure c-BN February 5th, 2016

Nanobiotechnology

Chemical cages: New technique advances synthetic biology February 10th, 2016

Nanoparticle therapy that uses LDL and fish oil kills liver cancer cells February 9th, 2016

Leading bugs to the death chamber: A kinder face of cholesterol February 8th, 2016

UTHealth research looks at nanotechnology to help prevent preterm birth February 7th, 2016

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







Car Brands
Buy website traffic