Can someone please detail how epigenetic changes happen

[Angelo]

Hi all I have been intrigued recently by epigenetics which allows for beneficial changes to happen deliberately in a parent individual.  Now I am not interested in the changed or turned on or off genes I am only interested in how these genes are instructed to be altered by a living parent without the need for any random mutation?  

So anyone know?

[Dagl1]

Epigenetics covers a lot of topics (I find that regulatory RNA's or RNA modification are also epigenetic, although of generally much smaller timelengths), the two most well known (researched) mechanisms would be DNA methylation (mostly CpG islands in promoter regions) and histone modifcations (the simplest concept, but not the only mechanism by which histone modificaitons work is to think of DNA as a string of negative charge. This string is wrapped around proteins (histones) like beads on a string, it just wraps around a little less than 1.5 times, so only a small portion (147 basepairs) of the total string is around each protein. To "read" (transcribe) a gene, a ring has to go over the string; if the string is wrapped tightly, it may not be able to due to friction with the histone, but if you make the histone negative, it will repel the negatively charged DNA, allowing for more room between the DNA and the histone, making it easier for this part of the genome to be transcribed.

[Angelo]

23 hours ago, Dagl1 said:

Epigenetics covers a lot of topics (I find that regulatory RNA's or RNA modification are also epigenetic, although of generally much smaller timelengths), the two most well known (researched) mechanisms would be DNA methylation (mostly CpG islands in promoter regions) and histone modifcations (the simplest concept, but not the only mechanism by which histone modificaitons work is to think of DNA as a string of negative charge. This string is wrapped around proteins (histones) like beads on a string, it just wraps around a little less than 1.5 times, so only a small portion (147 basepairs) of the total string is around each protein. To "read" (transcribe) a gene, a ring has to go over the string; if the string is wrapped tightly, it may not be able to due to friction with the histone, but if you make the histone negative, it will repel the negatively charged DNA, allowing for more room between the DNA and the histone, making it easier for this part of the genome to be transcribed.

Thanks for responding but you seem to be detailing the changes.  In the mouse and the cherry blossom smell with electricity experiment the changes that are initiated in the mind are in some way effecting the sperm cells of the male mouse where a learned fear of smell that is housed in the mind travels to living unmutated sperm cells.   The changes are well documented in the offspring but what is missing is the method of change that begins in the mind as the offspring are endowed with a life extending fear of cherry blossom odor.  Note that zero evolutionary time is needed for this

Edited January 6, 2020 by Angelo

[Endy0816]

3 hours ago, Angelo said:

Thanks for responding but you seem to be detailing the changes.  In the mouse and the cherry blossom smell with electricity experiment the changes that are initiated in the mind are in some way effecting the sperm cells of the male mouse where a learned fear of smell that is housed in the mind travels to living unmutated sperm cells.   The changes are well documented in the offspring but what is missing is the method of change that begins in the mind as the offspring are endowed with a life extending fear of cherry blossom odor.  Note that zero evolutionary time is needed for this

 

Possibly the fear hormones released modify how the odor molecule is physically being detected by the offspring and that leads to their fear response in turn.

 

 

 

 

 

 

Edited January 7, 2020 by Endy0816

[Angelo]

Just now, Endy0816 said:

 

Possibly the hormones released modify how the odor molecule is physically being detected and that results in the offspring's response.

 

The offspring is actually not part of my core question which is how does a painful situation in a healthy adult which centers around a brain response to stimuli modify that adults somatic cells?  This situation implies that an individual can by some unknown means determine what traits their offspring will have.  Like wishing for what you need and birthing it

[hypervalent_iodine]

I believe you are asking about epigenetic inheritance. There are papers on this. It is a rather broad topic. If you have access, this paper is a good overview. You may also like to look at the wiki article. 

[Endy0816]

10 hours ago, Angelo said:

The offspring is actually not part of my core question which is how does a painful situation in a healthy adult which centers around a brain response to stimuli modify that adults somatic cells?  This situation implies that an individual can by some unknown means determine what traits their offspring will have.  Like wishing for what you need and birthing it

Probably largely autonomous and limited. Only thing that makes is some kind of feedback loop.

Seems most concerned with passing on a snapshot of the current chemical environment.

 

Found an article saying:

Quote

The findings were also verified by comparing the epigenetic markers on the DNA of sperm, specifically on the gene responsible for detecting cherry blossoms. On the sperm of the cherry-blossom-fearing mice, there was less of the methylation that can silence genes, possibly pointing to a mechanism of how the information got passed down.

https://www.washingtonpost.com/national/health-science/study-finds-that-fear-can-travel-quickly-through-generations-of-mice-dna/2013/12/07/94dc97f2-5e8e-11e3-bc56-c6ca94801fac_story.html

[Dagl1]

A lot of instinctional fears are encoded in our genome, it seems not too absurd to assume that, a stimulus+fear response may use the already-existing instinctional fear machinery present in the brain. 
One reason why it is difficult to give a clear answer is that your genes and epigenetics only encode for what each cell does, but when looking at behavior, we observe a network of cells all working together, thus finding non-abstract/non-generalised answers is difficult. 

Let's take some biology-based fictional example I just came up with; Receptor X is comprised of 4 different unique subunits, of which 20 types are encoded by the genome. Strong fear response changes the subunit pattern to a higher amount of type 3-5-5-16 instead of the regular 3-5-5-12 (the numbers are just the subunit types we currently have for this receptor). These changes will be epigenetic: histone modifications, DNA methylation, RNA-mediated etc. Now only the neurons in your brain that contain were activated (strongly) during the fear response, will contain more 3-5-5-16 instead of the rest of the neurons (of the same type) that were not involved in this fear response. Now the receptor just activates slightly faster or slower (or whatever, its a bit different but not in any major way). But this can have enormous differences in behaviour. Now imagine that something also changes in the germ cells (they get more of a specific type of RNA, which remains (or is actively maintained) throughout the life of the new offspring. The mouse/organism may already instinctionally have strong responses to specific tastes, colours (think of specific male fish that attack everything that is red, because other they have evolved to do that) or sounds/smells or even shapes (we apes are pretty scared of snakes, which is not a learned-behaviour). The epigenetic changes may just lead to a different subunit composition later in the life, which as a result (how, is very difficult to really say in a causal/per cell/per molecule basis) now fears the specific stimulus.

In this case, having a good understanding of genetics, epigenetics, general cellular adaption and which types of behavior is already encoded within an organism, may make it easier to wrap your head around how this works.

-Dagl

[Sensei]

On 1/5/2020 at 11:18 PM, Angelo said:

Hi all I have been intrigued recently by epigenetics which allows for beneficial changes to happen deliberately in a parent individual.  Now I am not interested in the changed or turned on or off genes I am only interested in how these genes are instructed to be altered by a living parent without the need for any random mutation?  

So anyone know?

It depends on specie. Take for example bees.

"The queen–worker developmental divide is controlled epigenetically by differential feeding with royal jelly; this appears to be due specifically to the protein royalactin."

https://en.m.wikipedia.org/wiki/Royal_jelly

(epigenetics effects section)

(worker-bee and queen-to-be larvae are usually sisters)

Edited January 7, 2020 by Sensei