Features Partner Sites Information LinkXpress hp
Sign In
Advertise with Us
LGC Clinical Diagnostics

Download Mobile App




Imaging Technique Reveals 3D Structure of DNA and Chromatin

By LabMedica International staff writers
Posted on 09 Aug 2017
Researchers have developed a method for visualizing the three-dimensional structure of chromatin, which explains how the two meter long molecular chain of genomic DNA fits inside the nuclei of human cells.

Chromatin is a complex of macromolecules consisting of DNA, protein, and RNA. The primary functions of chromatin are to package DNA into a more compact, denser shape; to reinforce the DNA macromolecule to allow mitosis; to prevent DNA damage; and to control gene expression and DNA replication. Up to now there has been no method that enabled DNA and chromatin ultrastructure to be visualized and reconstructed unambiguously through the large three-dimensional volumes of intact cells.

To visualize and reconstruct chromatin ultrastructure and three-dimensional organization, investigators at the University of California, San Diego (USA) and the Salk Institute for Biological Studies (La Jolla, CA, USA) developed ChromEMT, a method that combined electron microscopy tomography (EMT) with a labeling method (ChromEM) that selectivity enhanced the contrast of DNA. This technique exploited a fluorescent dye that bound to DNA, and upon excitation, catalyzed the deposition of diaminobenzidine polymers on the surface, enabling chromatin to be visualized with OsO4 in an EM (electron microscope). Advanced multi-tilt EMT revealed the chromatin ultrastructure and three-dimensional packing of DNA in both human interphase cells and mitotic chromosomes.

The investigators reported in the July 28, 2017, online edition of the journal Science that ChromEMT enabled the ultrastructure of individual chromatin chains, heterochromatin domains, and mitotic chromosomes to be resolved in serial slices and their three-dimensional organization to be visualized as a continuum through large nuclear volumes in situ. ChromEMT stained and detected 30-nanometer fibers in nuclei purified from hypotonically lysed chicken erythrocytes. Furthermore, the investigators showed that chromatin was a disordered five- to 24-nanometer-diameter curvilinear chain that was packed together at different three-dimensional concentration distributions in interphase and mitosis. Chromatin chains had many different particle arrangements and bent at various lengths to achieve structural compaction and high packing densities.

Senior author Dr. Clodagh O'Shea, an associate professor at the Salk Institute for Biological Studies, said, "The findings reveal that nucleus DNA assembles five to 24-nanometer-diameter chromatin chains in a diversity of three-dimensional conformations and motifs. In contrast to ordered and rigid fibers, chromatin is a flexible chain that can collapse and pack together into three-dimensional domains that have a wide range of different concentration densities. This provides exciting new insights into how different gene sequences, interactions and epigenetic modifications can be integrated at the level of chromatin structure to regulate gene expression and inherited and maintained through cell division."

Related Links:
University of California, San Diego
Salk Institute for Biological Studies

Gold Member
Veterinary Hematology Analyzer
Exigo H400
Verification Panels for Assay Development & QC
Seroconversion Panels
New
H.pylori Test
Humasis H.pylori Card
New
Anti-HHV-6 IgM Assay
anti-HHV-6 IgM ELISA (semiquant.)
Read the full article by registering today, it's FREE! It's Free!
Register now for FREE to LabMedica.com and get complete access to news and events that shape the world of Clinical Laboratory Medicine.
  • Free digital version edition of LabMedica International sent by email on regular basis
  • Free print version of LabMedica International magazine (available only outside USA and Canada).
  • Free and unlimited access to back issues of LabMedica International in digital format
  • Free LabMedica International Newsletter sent every week containing the latest news
  • Free breaking news sent via email
  • Free access to Events Calendar
  • Free access to LinkXpress new product services
  • REGISTRATION IS FREE AND EASY!
Click here to Register








Channels

Molecular Diagnostics

view channel
Image: Researcher Kanta Horie places a sample in a mass spectrometer that measures protein levels in blood plasma and other fluids (Photo courtesy of WashU Medicine)

Highly Accurate Blood Test Diagnoses Alzheimer’s and Measures Dementia Progression

Several blood tests are currently available to assist doctors in diagnosing Alzheimer's disease in individuals experiencing cognitive symptoms. However, these tests do not provide insights into the clinical... Read more

Immunology

view channel
Image: The findings were based on patients from the ADAURA clinical trial of the targeted therapy osimertinib for patients with NSCLC with EGFR-activated mutations (Photo courtesy of YSM Multimedia Team)

Post-Treatment Blood Test Could Inform Future Cancer Therapy Decisions

In the ongoing advancement of personalized medicine, a new study has provided evidence supporting the use of a tool that detects cancer-derived molecules in the blood of lung cancer patients years after... Read more

Microbiology

view channel
Image: Schematic representation illustrating the key findings of the study (Photo courtesy of UNIST)

Breakthrough Diagnostic Technology Identifies Bacterial Infections with Almost 100% Accuracy within Three Hours

Rapid and precise identification of pathogenic microbes in patient samples is essential for the effective treatment of acute infectious diseases, such as sepsis. The fluorescence in situ hybridization... Read more
Copyright © 2000-2025 Globetech Media. All rights reserved.