Navigation Links
Physical reason for chromosome shape discovered
Date:1/14/2014

This work gives a solution to a fundamental question in structural biology: Why do metaphase chromosomes have their characteristic elongated cylindrical shape? The proposed solution is consistent with the structure of metaphase chromatin and with the nanomechanical properties of chromatin and chromosomes. It is a research at the interface between biology (higher order chromatin structure) and physical sciences (supramolecular structures and nanomaterials). This approach goes beyond the capabilities of current structural biology based on X-ray crystallography, because it allows the study of an enormous supramolecular assembly that cannot be crystallized. The work has been published in the Journal of the Royal Society Interface.

In the cell nucleus, genomic DNA molecules are associated with histone proteins and form long chromatin filaments containing many nucleosomes. Previous microscopy studies performed by researchers at the Chromatin Laboratory directed by professor Joan-Ramon Daban (Biosciences Unit of the Department of Biochemistry and Molecular Biology, UAB) showed that, during cell division, chromatin filaments are folded into multilayer planar structures. This discovery led to the thin-plate model in which it was proposed that condensed chromosomes are formed by many stacked layers of chromatin oriented perpendicular to the chromosome axis.

The measurements performed by professor Daban show that chromosomes of different animal and plant species exhibit great differences in size (which are dependent on the amount of DNA that they contain), but in all cases chromosomes are elongated cylinders that have relatively similar shape proportions (the length to diameter ratio is approximately 13). This study demonstrates that it is possible to explain this morphology by considering that chromosomes are self-organizing supramolecular structures formed by stacked layers of planar chromatin having different nucleosome-nucleosome interaction energies in different regions. The nucleosomes in the periphery of the chromosome are less stabilized by the attractive interactions with other nucleosomes and this generates a surface potential that destabilizes the structure. Chromosomes are smooth cylinders because this morphology has a lower surface energy than structures having irregular surfaces. The symmetry breaking produced by the different values of the surface energies in the telomeres and in the lateral surface explains the elongated structure of the chromosomes.

The results obtained by other authors in nanomechanical studies of chromatin and chromosome stretching have been used to test the proposed supramolecular structure. It is demonstrated quantitatively that internucleosome interactions between chromatin layers can justify the work required for elastic chromosome stretching. Chromosomes can be considered as hydrogels with a lamellar liquid crystal organization. These hydrogels have outstanding elastic properties because, in addition to the covalent bonds of the DNA backbone, they have attractive ionic interactions between nucleosomes that can be regenerated when the chromosome suffers a deformation. This self-healing capacity has been observed in nanotechnology studies of other hydrogels stabilized by ionic interactions. In the cell, this may be useful for the maintenance of chromosome integrity during mitosis.


'/>"/>

Contact: Joan-Ramon Daban
Joanramon.daban@uab.cat
34-935-811-616
Universitat Autonoma de Barcelona
Source:Eurekalert  

Related biology news :

1. Increasing clarity for medics in suspected physical abuse cases
2. NIH-funded study examines use of mobile technology to improve diet and physical activity behavior
3. UTHealth study addresses barriers to physical activity counseling
4. Harvards Wyss Institute to develop smart suit that improves soldiers physical endurance
5. Iron, vitamins could affect physical fitness in adolescents
6. Childrens physical activity levels are not enough to counteract sedentary lifestyles
7. Biophysical Society names 5 2013 award recipients
8. Biophysical Society names 2013 Distinguished Service, Emily M. Gray, and Founders awardees
9. New study finds milk-drinking kids reap physical benefits later in life
10. Dark Energy: Life beneath the seafloor discussed at upcoming American Geophysical Union conference
11. UT study: Students who are more physically fit perform better academically
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
Physical reason for chromosome shape discovered
(Date:6/21/2016)... , June 21, 2016 NuData ... the new role of principal product architect and ... the director of customer development. Both will report ... technical officer. The moves reflect NuData,s strategic growth ... response to high customer demand and customer focus ...
(Date:6/9/2016)... control systems is proud to announce the introduction of fingerprint attendance control software, allowing ... are actually signing in, and to even control the opening of doors. ... ... ... Photo - http://photos.prnewswire.com/prnh/20160609/377487 ...
(Date:6/2/2016)... 2, 2016 The Department of Transport ... the 44 million US Dollar project, for the , ... including Personalization, Enrolment, and IT Infrastructure , to ... production and implementation of Identity Management Solutions. Numerous renowned international ... Decatur was selected for the most compliant ...
Breaking Biology News(10 mins):
(Date:12/5/2016)... Dec. 5, 2016  Eisai Inc. announced today ... study of rufinamide, which were presented at the ... (AES) held from December 2-6 in ... safety, tolerability and cognitive data showed that patients ... safety and tolerability profiles, cognitive development and behavior, ...
(Date:12/4/2016)... ... December 02, 2016 , ... A proposed five-year extension for ... funded research and development is welcome news for the photonics community, say leaders ... As part of the National Defense Authorization Act (NDAA) compromise agreement finalized today ...
(Date:12/4/2016)... and CAMBRIDGE, Mass. and ... Dec. 4, 2016 SystemOne, a company ... software platforms for the developing world, and Daktari ... a reality with its portable and ultrasensitive immunoassay-based ... a development and license agreement to integrate Daktari,s ...
(Date:12/2/2016)...  The Multiple Myeloma Research Foundation (MMRF) today announced ... SM —the largest and most comprehensive study driving new ... be presented at the 58 th American Society ... San Diego from December 3-6. The ... well as identify pathways and targets for new drug ...
Breaking Biology Technology: