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
Cornell University News Service

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:

(Date:11/12/2015)... 2015  Arxspan has entered into an agreement ... for use of its ArxLab cloud-based suite of ... partnership will support the institute,s efforts to electronically ... information internally and with external collaborators. The ArxLab ... the Institute,s electronic laboratory notebook, compound and assay ...
(Date:11/9/2015)... , Nov. 09, 2015 ... addition of the "Global Law Enforcement ... offering. --> http://www.researchandmarkets.com/research/52ggmn/global_law ) has ... Law Enforcement Biometrics Market 2015-2019" report ... and Markets ( http://www.researchandmarkets.com/research/52ggmn/global_law ) has announced ...
(Date:10/29/2015)... Oct. 29, 2015  The J. Craig Venter Institute ... "DNA Synthesis and Biosecurity: Lessons Learned and Options for ... Health and Human Services guidance for synthetic biology providers ... --> --> Synthetic ... the potential to pose unique biosecurity threats. It now ...
Breaking Biology News(10 mins):
(Date:11/24/2015)... /PRNewswire/ - Aeterna Zentaris Inc. (NASDAQ:  AEZS) (TSX: ... 11,000 post-share consolidation (or 1,100,000 pre-share consolidation) Series ... Warrants") subject to the previously disclosed November 1, ... which will result in the issuance of 365,518 ... issuance of such shares, there will be approximately ...
(Date:11/24/2015)... QC , Nov. 24, 2015 /CNW Telbec/ - ProMetic ... "Corporation") announced today that Mr. Pierre Laurin , President ... corporate presentation at the upcoming Piper Jaffray 27 th ... Palace Hotel, on December 1-2, 2015. st ... available for one-on-one meetings throughout the day. The presentation will ...
(Date:11/24/2015)... ... November 24, 2015 , ... Whitehouse Laboratories is pleased ... The new stand-alone facility will be strictly dedicated to basic USP 61, USP 62 ... clients the chance to have complete chemistry and micro testing performed by one supplier. ...
(Date:11/23/2015)... ... November 23, 2015 , ... ... the development of its Nexera UC Unified Chromatography system. The award from R&D ... significant new products of the year in the analytical and testing category. R&D ...
Breaking Biology Technology:
Cached News: