yes, please elucidate, y'all. This topic is fundamental to my screenplay that will capitalize on the growing popularity of genealogy and gardening. Janeane Garafolo and whoever is today's analogue for Cary Grant are the leads.
Giraffes stretched out their necks to reach high leaves which caused their histones H3 proteins to be methylated at lysines 9 and 27.
I could give you a real explanation since this is one of the subtopics I work on in fairly significant detail. But I'll let someone else provide the explanation and just chime in with snarky comments.
Epigenetics makes me sad, because it makes it less likely that we'll successfully clone extinct animals.
I appreciate that you're sticking to your convictions.
A coworker who lives just down the street is the real expert- whenever this topic comes up in the popular press he's quoted in the NYT.
It's a pretty big subject. DNA methylation regulates gene expression during development-- you have the same genome that you did as a blastula, but different genes are expressed now due to DNA methylation. When repeated cell division or environmental stress demethylates pieces of the genome, cancer becomes much more likely. At least some variation between individuals in DNA methylation is heritable. It's not Lamarckian in the sense that the proteins responsible for doing this are part of the organism-- a zygote with defective methylases would not be viable at all, and a zygote whose methylation was perturbed by a space virus or something would not pass the perturbing space virus on to its descendants. The corner case is imprinting. I don't know how much fetal environment affects the process, obviously there will be some effect, in many cases a well-studied effect.
Histone modifications, also referred to as epigenetic changes, also implicated in cancer, are not known to be heritable. Personally, I think this makes them unpromising, but lots of people are looking at them. Recently developed techniques make this easy to do cheaply.
I think this makes them unpromising, but lots of people are looking at them.
Do you mean not known the be heritable between cell divisions, or between generations of organisms?
today's analogue for Cary Grant
Clooney, right?
Regulation of expression is pretty messy-- my understanding is that studying when histones clump together and when they don't is very difficult, reproducbility of results with differeing techniques is not easy. I think of it as a stochstic process, many differing microstates of epigenetic modification and associated histone kinetics leading to viability. The stochasticity is IMO a true and essential p[roperty of the process in the cell, not just due to the considerable difficulties of sample prep and measurement.
Not much can be said definitely, so not much in textbooks. Not like protein translation, which is deterministic. The epigenetic regulations that have been well studied are IMO atypical due to their extreme effects, which are sex-linked so perfect for genetics-- imprinted genes.
snark away, btw, this is not my main thing at all, just something I'm peripherally aware of.
I have a vague memory of things like abuse and serious amounts of lifetime stress not just being associated with negative health outcomes in the individual, but also in subsequent generations, and not just because the stressor itself is ongoing. Is epigenetics methylation spearmint going on there?
Clooney, Cusack, Carrey, Carell, Colbert could all be written for.
13. Don't know. Fetuses are subject to all kinds of hormones from mom, plus she has to grow a whole new organ as an adult.
Any factors that affect either of those processes would also affect the fetus without invoking something that's harder to study and more general.
Lamarck is dead. His death is the hour of fate.
1 is a joke, right? Janeane Garofalo's not going to be somewhere, like unfogeedycon, where the magic of my overbearing banter will make her smile, right?
Lamarck is dead, but he changed everything for future generations...
Histone mods may be biochemically important, of course, but if some state of these has higher fitness, the state must be heritable to be plausible as a causal agent or a drug targets.
not a joke but merely the person that I see as the reference librarian who becomes the unexpected hero of the piece as she leads a merry band of octogenarian genealogists to victory over the bad guys.
You're saying you won't give me her number. Got it.
not at least until I try my overbearing banter on her.
the state must be heritable to be plausible as a causal agent or a drug targets
This is why I asked about cell vs organism inheritance- if it's heritable between cells it's certainly a drug target since fitness selection of cell populations = cancer.
23. Oh, that's true, maybe a line of thinking like angiogenesis inhibitors could be useful. I don't know how to think that way, at least not quickly, though.
||
What does it say about my aesthetic judgment and my political correctness that I like the Bush paintings?
I take them to be self-portraits. In the first one, I find something particularly piquant about the perspective used on the face in the mirror.
I suppose it's a Godwin violation to compare Bush's work to that of Hitler.
|
Oh sure, threadjack the one discussion where I get to be near the top of the hivemind for a little while.
Where the snowpocalypse thread?
I'll chime in as another scientist with some knowledge on this subject. There doesn't seem to be a real answer posted yet that would answer the question for non-scientists, so here goes:
In a sense, yes. The experiences of the organism result in changes that are passed on to their offspring as epigenetic material. It's not genetic material, but it's pretty darn close to it, sitting right next to it.
I was intentionally vague in my use of the work 'organism.' The scientific community knows some of how epigenetics works for individual cells, and it seems like it may also be true for whole organisms. Better yet, it may also be true for whole organisms in a way that really matters, so that the fitness of the offspring is changed.
When people talk about DNA methylation and histone modifications, these are the specific molecules that are being changed in ways that are a) non-genetic and b) heritable. Is this everything? Probably not. Is it important? Probably yes.
Feel free to chime in or call me out on something I didn't say correctly.
Here's a way to think about it- any protein that's going to be made has to be encoded in the DNA*. You don't have luciferase so you're never going to glow, sorry. However, just because you have the code to make a protein doesn't mean you're going to or that it will be made at a certain time. Where and when proteins are made is just as important as what they are (ever heard of a teratoma?) The where and when is what's controlled a lot by epigenetics, as well as other regulatory mechanisms that were also recently discovered like RNA mediated silencing.
* There is also the issue of alternative splicing, where bits of protein code are combined differently under different conditions to make different producs. I can't think of any examples of that are specifically under epigenetic control but I imagine there are some.
And that topic was already used to semi-hijack another thread here. Pf is worse than Hitler and Bush combined.
There's something confusing to me in this whole discussion, which is that from a pre-DNA discover point of view, this is all "genetic." But I guess once DNA was discovered, genetic got redefined to mean something more specific, namely stuff in DNA.
Or does "non-genetic" mean something more than just "not encoded in DNA"?
I think post Mendel pre-DNA genetic generally meant heritable.
911, from German Gen, coined 1905 by Danish scientist Wilhelm Ludvig Johannsen (1857-1927), from Greek genea "generation, race"
They said all along the heaviest snow was after 7pm, that's why I don't know why they closed everything all day and BANNED CARS FROM THE ROAD at 4pm.
Where the snowpocalypse thread at?
All along? At one point yesterday evening I was reading something that said the heaviest snow was between 2 and 5 PM. Maybe I was reading a uniquely unreliable source. I can't remember where that was.
Genetic can refer to "what's passed on between generations" or to "what's encoded in the genome of a developing organism", and this sliver of biochemistry affects development but may not be passed on, or at least not in a simple way.
The complication here is: It is very clear how variations between individuals in DNA are passed from parents to descendants. It is not clear how variations in methylation pattern of either DNA or of the histones which bundle it (and which can also be actylated, along with other possibiliyties) can be passed on.
People don't understand in much detail what actually gets reproducibly modified (there's variation from cell to cell), or how the mechanisms that produce the modification work. Cheap sequencing allows access to mountains of data that's hard to figure out, and at least for me, it takes a fair amount of work to distinguish "this looks promising, maybe" from "reproducible results even with different samples and assays."
I went in the bank this morning at about noon to try to get some quarters for laundry and everyone had already left.
Are there any good, accessible books on epigenetics?
A lot of the targets involved in stem cell reprogramming (Oct4, Sox2) are involved with epigenetic reprogramming. That is, reprogramming a differentiated cell back to a cell type that can become any other cell type.
There's a CSHL press book from a few years back that's pretty good, Reinberg. I am more interested in developmental regulation than in histones, which lattter topic is complicated before adding in the possible modifications on the tail.
For developmental regulation, methylation is the other word to look for.
And then, if you want to really freak out, there's the spliceosome!
As far as I understand it, the solution is that the causality still runs from genotype to phenotype; you can't meaningfully hope to embigger your gag, pol, and env by palaeodieting.
Biology really is a field where the great British motto works. (-"it's more complicated than that")
Pf is worse than Hitler and Bush combined.
It's true! I'm a terrible painter.
I think a major thing that "genetic" implies, per 31, is that it's non-Lamarckian; you have it, and you'll pass it down, but your behavior doesn't modify it. That's basically true for DNA. Some of these epigenetic mechanisms aren't as clear, and the possibility gets people excited.
