#methylome

[currentsinbiology]

A mechanism of epigenetics...

Biologists unravel another mystery of what makes DNA go 'loopy'

Scientists discovered another key to how DNA forms loops and wraps inside the cell nucleus -- a precise method of "packing" that may affect gene expression.

The journal Science published the research by biologists at Emory University, showing that a process known as hemimethylation plays a role in looping DNA in a specific way. The researchers also demonstrated that hemimethylation is maintained deliberately -- not through random mistakes as previously thought -- and is passed down through human cell generations.

"In order for a protein called CTCF to make loops in the DNA, we discovered that it needs to have hemimethylated DNA close by," says Emory biologist Victor Corces, whose lab conducted the research. "Nobody had previously seen that hemimethylated DNA has a function."

Chromatin is made up of CTCF and other proteins, along with DNA and RNA. One role of chromatin is to fold and package DNA into more compact shapes. Growing evidence suggests that this folding process is not just important to fit DNA into a cell nucleus -- it also plays a role in whether genes are expressed normally or malfunction.

Chenhuan Xu, Victor G. Corces. Nascent DNA methylome mapping reveals inheritance of hemimethylation at CTCF/cohesin sites. Science, 2018; 359 (6380): 1166 DOI: 10.1126/science.aan5480

Interior of a cell showing the nucleus with the chromatin fiber (yellow) arranged in the three-dimensional space by loops formed by the CTCF protein (shown in pink). DNA is represented by thin blue lines on the chromatin.Credit: Graphic by Victor Corces.

[cadmar]

Similar yet different neurons

Recently, science through the analysis of methylome, have discovered that two neurons even in the same brain region, look similar, but behave differently. They have discovered, so far, in the frontal cortex, the executive function area (complex thinking, personality, social behaviours, decision making, and others), there are 21 sub-types of neurons.

It is possible that only certain sub-types of neurons are triggered and excited to form our memories.  If this is the case, then the other neurons do not hold our memories that may lead to having a different process of perceptions and awareness.

This makes sense, as can the dead awaken the dead?  Can the dead make the dead alive?  Can the dead give life to the dead?  The neurons that formed our memories, are incapable of triggering and exciting the neighbouring neurons.

There must be another way of seeing the world without memory and to excite and trigger these non-memory neurons.

[epigentek]

The Quebec Ice Storm of 1998 was a devastating time that plunged more than 3 million Quebecers into frigid darkness without electricity for as long as 45 days. Now, more than 15 years later, researchers from McGill University and the Douglas Mental Health University are finding out that the length of time a pregnant woman went without electricity during this time predicts her child’s epigenetic profile.

Scientists have discovered a unique DNA ‘signature’ of children who were in the womb while the massive ice storm occurred. Five months following the disaster, women who were pregnant during the storm were recruited and their degrees of hardship and distress were assessed in a large study known as Project Ice Storm.