HOME >> BIOLOGY >> NEWS
Optical tweezers show how DNA uncoils

ITHACA, N.Y. -- By using optical tweezers to pull individual strands of chromatin -- the DNA-protein complex that chromosomes are made of -- researchers have seen for the first time how information in fundamental genetic packaging units, called nucleosomes, might become accessible to molecules that "read" it.

The report by physicists and biologists at Cornell University and the University of Massachusetts appears in the current Proceedings of the National Academy of Sciences (Vol. 99, Issue 4), "Mechanical Disruption of Individual Nucleosomes Reveals a Reversible Multistage Release of DNA." It marks the first direct observation of the dynamic structure of individual nucleosomes. Chromosomal DNA is packaged into the compact structure of the nuclesome with the help of specialized proteins called histones. The complex of DNA plus histones in cells of higher organisms is called chromatin.

Michelle D. Wang, assistant professor of physics at Cornell,
who led the scientific team, said
the researchers are proposing a three-stage model for the way in which nucleosomal units in chromatin open to reveal their DNA to enzymes like RNA polymerase.

The three stages became apparent when a nucleosome was uncoiled as the DNA was stretched with increasing force, says Brent Brower-Toland, lead author of the article and a research associate in Cornell's Laboratory of Atomic and Solid State Physics. Describing the release of DNA from a single nucleosome, he says: "When we pulled on an individual chromatin fiber with increasing force, low force initially released 76 base pairs of DNA per nucleosome, then higher forces yielded 80 more base pairs with the histones still bound to the DNA, followed by histone detachment at still higher forces. But, if we released the fiber before the histones were detached, the nucleosomes were able to reassemble themselves and the whole process could be repeated." "Of course the basic plan -- nucleosomes and
'"/>

Contact: Roger Segelken
hrs2@cornell.edu
607-255-9736
Cornell University News Service
4-Mar-2002


Page: 1 2 3

Related biology news :

1. Optically recording millisecond brain nerve impulses
2. Optical trap provides new insights into motor molecules - nature`s ultimate nanomachines
3. Optical microsystems emerge in industrial applications
4. Growing Up On Their Own: Smart Plastics Organize Themselves Into Useful Optical Devices
5. Optical Microscopy Shines Light On Biology
6. Controlling biomolecules with magnetic tweezers
7. With optical tweezers, researchers pinpoint the rhythmic rigidity of cell skeletons

Post Your Comments:
*Name:
*Comment:
*Email:
TAG: Optical tweezers show how DNA uncoils

(Date:4/17/2014)... and pathogens that devastate honeybees in Europe, Asia and ... do not appear to be impacting native honeybee populations ... researchers., The invasive pests include including Nosema microsporidia ... honeybees appear to be resilient to these invasive pests, ... control pests in Europe, Asia and the United States ...
(Date:4/17/2014)... Current Biology on April 17 have discovered ... Brazilian insects, which represent four distinct but related species ... example of an animal with sex-reversed genitalia. , ... animals, Neotrogla is the only example in ... Yoshizawa from Hokkaido University in Japan. , During copulation, ...
(Date:4/17/2014)... Scientists have uncovered a new way the immune system ... aid efforts to use immune cells to treat illness. ... have the immunological equivalent of "neighborhood police" specialized ... single organ, instead of an entire city, the body. ... St. Louis have shown that the liver, skin and ...
Breaking Biology News(10 mins):East African honeybees are safe from invasive pests… for now 2East African honeybees are safe from invasive pests… for now 3In sex-reversed cave insects, females have the penises 2Some immune cells defend only 1 organ 2
(Date:1/15/2014)... SAN JOSE, California , January 15, 2014 ... antibody-drug conjugates for cancer, today announced the appointment of Thomas ... Reynolds has over 20 years, development experience gained in the ... Genetics. "I am delighted to welcome Tom at ...
(Date:1/15/2014)... (PRWEB) January 15, 2014 This webinar ... nonclinical and clinical safety assessment in biosimilars. , Regulatory ... for biosimilar drug development, however the complex nature of ... quality, safety and efficacy extremely challenging. Based on the ...
(Date:1/15/2014)... January 15, 2014 More than 5 ... about 1 in 3 seniors will die with Alzheimer’s ... These jaw-dropping figures have shocked many Americans into looking ... help prevent these tragic age-related cognitive disorders. Jonathan Weisman, ...
(Date:1/15/2014)... The Microcompetition with Foreign DNA theory explains ... these latent viruses is the Epstein Barr Virus (EBV), and ... (RA) is a chronic inflammatory disease that destroys the body’s ... RA patients have high concentrations of EBV DNA in their ...
Breaking Biology Technology:Oxford BioTherapeutics Appoints Thomas C Reynolds MD, PhD to its Board of Directors 2Oxford BioTherapeutics Appoints Thomas C Reynolds MD, PhD to its Board of Directors 3Xtalks Life Sciences Webinar Examines Safety Assessment of Biosimilars 2Biohack Pure Offers 5 Tips for Increasing Memory in 2014 2Study: Rheumatoid Arthritis (RA) Patients Have EBV; The CBCD Says this is Consistent with Microcompetition 2Study: Rheumatoid Arthritis (RA) Patients Have EBV; The CBCD Says this is Consistent with Microcompetition 3
Cached News: