In the journal Angewandte Chemie, a British team has now introduced a new method that makes it possible to enrich the rare gene segments that contain the modified base hydroxymethylcytosine and to identify individual hydroxymethylcytosine molecules in DNA. Such modifications are associated with autoimmune diseases and cancer.
The bases adenine, guanine, cytosine, and thymine make up the genetic code. Every cell of the body contains an identical set of complete genetic material. However, the various tissues in the body are very different from each other.
This is because the cells have the ability to transcribe only a specific selection of genes into proteins, leaving other genes unused. Epigenetic factors such as “markers” on the DNA control this process.
The base cytosine can be equipped with different side groups, such as a methyl or hydroxymethyl group. Dense methylation of regulatory gene segments switches off the corresponding genes. During development of the embryo, methylation patterns initiate cell differentiation.
Changes in the methylation patterns are associated with autoimmune diseases and cancer. Hydroxymethylcytosine patterns also seem to play a role in the differentiation of embryonic stem cells as well as in gene expression in cells of the central nervous system.
Sequencing techniques that can be used to specifically detect epigenetic bases are thus very important. To date, the identification of hydroxymethylcytosine has required complex, expensive, or error-prone processes. A team led by Hagan Bayley at the University of Oxford University has now developed a chemical modification that allows for the differentiation of hydroxymethylcytosine and methylcytosine through sequencing in nanopores.
Developed by Oxford Nanopore, a company formed by Hagan Bayley in 2005, the nanopore method is a highly promising alternative to the sequencing of individual DNA molecules without an amplification step. Fed by an enzyme, a single strand of DNA threads through a membrane-embedded protein pore.Depending on which of the bases is in the narrowest part of the pore at a given time, there is a characteristic change in the flow of current through the pore.
A chemical reaction between hydroxymethylcytosine, bisulfite, and a cysteine-containing peptide that leaves the other bases—including methylcytosine—unchanged, greatly improves the resolution as the various bases result in differences in current.
Importantly, it is possible to attach a fluorescent marker to the modified site, or a molecular “eye” that can be used to attach the rare hydroxymethylcytosine-containing DNA fragments to “hooks” that allow the fragments to be enriched over unmodified fragments, enabling rapid sequence analysis.About the Author
Author: Hagan Bayley, University of Oxford (UK), http://bayley.chem.ox.ac.uk/hbayley/Title: Single-Molecule Detection of 5-Hydroxymethylcytosine in DNA through Chemical Modification and Nanopore Analysis
Angewandte Chemie International Edition, Permalink to the article: http://dx.doi.org/10.1002/anie.201300413
Microscope measures muscle weakness
16.11.2018 | Friedrich-Alexander-Universität Erlangen-Nürnberg
Good preparation is half the digestion
16.11.2018 | Max-Planck-Institut für Stoffwechselforschung
Researchers at the University of New Hampshire have captured a difficult-to-view singular event involving "magnetic reconnection"--the process by which sparse particles and energy around Earth collide producing a quick but mighty explosion--in the Earth's magnetotail, the magnetic environment that trails behind the planet.
Magnetic reconnection has remained a bit of a mystery to scientists. They know it exists and have documented the effects that the energy explosions can...
Biochips have been developed at TU Wien (Vienna), on which tissue can be produced and examined. This allows supplying the tissue with different substances in a very controlled way.
Cultivating human cells in the Petri dish is not a big challenge today. Producing artificial tissue, however, permeated by fine blood vessels, is a much more...
Faster and secure data communication: This is the goal of a new joint project involving physicists from the University of Würzburg. The German Federal Ministry of Education and Research funds the project with 14.8 million euro.
In our digital world data security and secure communication are becoming more and more important. Quantum communication is a promising approach to achieve...
On Saturday, 10 November 2018, the research icebreaker Polarstern will leave its homeport of Bremerhaven, bound for Cape Town, South Africa.
When choosing materials to make something, trade-offs need to be made between a host of properties, such as thickness, stiffness and weight. Depending on the application in question, finding just the right balance is the difference between success and failure
Now, a team of Penn Engineers has demonstrated a new material they call "nanocardboard," an ultrathin equivalent of corrugated paper cardboard. A square...
09.11.2018 | Event News
06.11.2018 | Event News
23.10.2018 | Event News
16.11.2018 | Health and Medicine
16.11.2018 | Life Sciences
16.11.2018 | Life Sciences