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What is epigenetic regulation?

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What is epigenetic regulation?

Postby KTK » Tue Mar 29, 2005 2:42 am

What is epigenetic regulation?
Last edited by KTK on Mon May 09, 2005 9:45 am, edited 1 time in total.
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Postby GreenDog » Tue Mar 29, 2005 9:00 am

The study of heritable changes in gene function that occur without a change in the DNA sequence. Meaning, effects not encoded in DNA, but cause different phenotypes…
In classic genetics whatever is encoded in the DNA will be expressed, epigenetics causes an alternative expression pattern from the "expected" based on genetic capacity only.

Might be regulated by:
DNA Methylation
Histon acetylation/deacetylation & methylation
PTGS (Post Transcriptional Genomic Silencing, Plants)
Genomic Imprinting (Mammals)
dsRNA (RNAi)

Examples:
Mule- Hinny, both are the offspring of a horse and a donkey but they are different and it depends on who was the father and who was the mother.

Silent X- which X gets deactivated in a female?
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Postby 2810712 » Tue Mar 29, 2005 10:21 am

[epi= on ] Thus, i thought epigenomics is limited to the factors on the gene , and not others that may affect gene expression. Was I correct? ? ?
I've also heard about cis- and trans- forms of genes, what are those? They seem to be related to epigenomics , I think.
Do U know that same as the Human Genome Project, HEP [ human epigenome prij. ] is also, gointo be completed.

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Postby GreenDog » Tue Mar 29, 2005 1:54 pm

As far as I know, all the things I stated are considered epigenetisc, and “on” means above the level op pure DNA.
As for trans genes, maybe you mean trans splicing?
Most genes ate splices in cis- from the same mRNA. Some genes even in eukaryotes are created on a “plycistronic” RNA, then comes a splice-leader which splices the exon out adding itself at the beginning, a polyA tail is added and we get a monocistronic mRNA.
Splicing is also epigenetics because it depends not only on the strength of the splice sites, but also on the different helping proteins which are differently expressed in different tissues.
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How do u read a southern blotting?

Postby KTK » Tue Mar 29, 2005 6:19 pm

How is a southern blotting diagram read? and how can u tell from a gel illustration which types of gametes are are methylated?
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epigenetic regulation

Postby KTK » Wed Mar 30, 2005 3:40 am

I'm sorry, i don't think i understand fully what epigenetic regulation is...is it a mutation in the DNA.... how does it work?
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Postby GreenDog » Wed Mar 30, 2005 10:49 am

Epigenetic regulation has nothing to do with mutation, the DNA is normal (w.t.), other things affect regulation, for example:
Let's consider a hypothetical gene A that regulates fur color in mice and located on an autosome. The father has an allele fur black color and the mother for white.
In classic genetics, there are two possibilities:
Dominance: the black in dominant over the white and the offspring will be black.
Codominance: both phenotypes are expressed and the mice will be gray.
Epigenetics: (for example)
Whatever is methylated is expressed. Let's assume that the maternal genes are methylated- the mice will be white.( If the paternal genes are methylated they will be black.)
In any case if we perform a reciprocal experiment (i.e. black mother white father) with the same assumptions we get:
Dominance: Black
Codominance: Gray
Epigenetics: Black

As for the southern I'm hardly an expert but…
I imagine you are working on a known gene so you have the sequence, you have a specific probe for it (for detection). You treat your DNA with restriction enzymes (knowing that the restriction sites in the maternal and paternal gametes are the same).
Then you follow the procedure preparing a gel with four lanes:
Ladder (marker to know the size of the fragments)
Maternal DNA
Paternal DNA
Control (either of them, but demethylated for sure!)
At the end you'll get your bands the methylated DNA if "heavier" so it will run less on the gel, and thus you know what is methylated.
(I have never done it, I just imagine it's a possible way…)
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What is the significance of methylation?

Postby KTK » Wed Apr 06, 2005 8:33 pm

What exactly is the significance of methylation?
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Postby MrMistery » Wed Apr 06, 2005 8:48 pm

Strange thing... Here is what my genetics book says:
By the methilation of citozine at the carbon from the 5 position you get 5-metil citozine. This is a method of silencing the gene, as it can not be transcripted when it is in this state. The process takes place in the so called CpG islands, located in the promoter of the eukaryotic genes
"As a biologist, I firmly believe that when you're dead, you're dead. Except for what you live behind in history. That's the only afterlife" - J. Craig Venter
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