Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Transgenerational Epigenetic Inheritance: the story of learned avoidance

elifesciences.org

Post reply on HN
Print view View original

61–70 of 101 posts

Re: Transgenerational Epigenetic Inheritance: the story of learned avoidance

#61

Post by BobbyTables2 »

roughly wrote: post #40
unwise-exe wrote: post #39

Earlier quoted context omitted.

>>> (As if first time mothers didn’t have enough to worry about - stop stressing so much, it could lead to long-lasting irreversible changes to your fetus!) This is plainly not plausible. "Irreversible" doesn't play well with the length of time humans have been a thing.

Ask a parent what they hear when they hear “irreversible” in conjunction with their child. I promise nobody mistook that for “until the heat death of the universe,” but I can add a note if you really think it’s warranted.

You definitely make a good point.

But even reversible changes aren’t always “reversed”. They aren’t necessarily minor.

Sure, breaking an arm or skipping high school can be a “reversible” change. But not often not fully “reversed” and/or not done so in a negligible time frame. There are costs. Seems like biological development could be similar.

Re: Transgenerational Epigenetic Inheritance: the story of learned avoidance

#62

Post by morkalork »

Aurornis wrote: post #59
morkalork wrote: post #53

Earlier quoted context omitted.

There's some long running research on the effect in humans like this: https://theconversation.com/moms-prenatal-hardship-turns-bab... https://pubmed.ncbi.nlm.nih.gov/26098974/

Those are articles about maternal stress during pregnancy. The trans-generational epigenetic inheritance proponents claim that trauma can induce lasting generational effects spanning multiple levels of descendants, even if it doesn’t occur during to the mother during pregnancy. The paper this HN submission is talking about claims to have found an effect like this that persists for 4 generations. A key problem with th…

I suppose one would have to follow the cohort and see if the epigenetic changes observed so far carry over into their own children. I do find it interesting that stress in the mother becomes higher BMI in the offspring. It makes sense if you're talking about animals trying to survive in a harsh environment.

Re: Transgenerational Epigenetic Inheritance: the story of learned avoidance

#63

Post by __MatrixMan__ »

terminalshort wrote: post #38
__MatrixMan__ wrote: post #17

Earlier quoted context omitted.

I think that nowadays "gene" refers only to a subset of a nucleic acid. Sequences of ACTG (or ACUG in the case of RNA) only, and only in that organism's chromosomes. If you inherit a virus from your mother, for instance, I think most would call that non-genetic inheritance, even though viruses have genes too. Same goes for methyl and acetyl markers, transcription factors, nutrients, toxins, and whatever else comes al…

Got it. I had thought that actual genes were only a part of what was considered "genetics."

Back in the day when they didn't know which cellular chemical was responsible for the majority of heritability I think the usage was indeed more general. But now we have "the central dogma of biology" which puts nucleic acids on a pedestal. Convenient to have rules so you can keep track of their many exceptions.

Re: Transgenerational Epigenetic Inheritance: the story of learned avoidance

#64

Post by quesera »

shevy-java wrote: post #11
Aurornis wrote: post #6

Earlier quoted context omitted.

Epigenetic inheritance is a mechanism whereby traits could be passed from one generation to the next without modifying the underlying genetic DNA. The mechanism would alter the expression of different parts of DNA. It’s a very young field with a lot of open questions. The concept has been adopted and abused in the mainstream so you have to be careful to separate the science from the pseudoscience.

> It’s a very young field https://en.wikipedia.org/wiki/Epigenetics#Definitions That depends on the definition. But, if we use the modern definition, it emerged (or re-emerged) in the 1990s. It's not old, indeed, but I also would no longer call it "very young". It's soon 40 years in the modern definition, and much older if we include prior discussions.

A young field can be immature, regardless of age.

E.g., I would regard computer science as a very young field.

Re: Transgenerational Epigenetic Inheritance: the story of learned avoidance

#65

Post by skissane »

macleginn wrote: post #26
shevy-java wrote: post #8

So Lamarck wasn't entirely incorrect either. Darwin would have been fascinated by these results.

There has been aruably a more serious blow to the pure Darwinian evolution (this is all epigenetics, after all): non-random occurrence of useful mutations in populations exposed to particular diseases. https://pubmed.ncbi.nlm.nih.gov/40854136/

I wonder how that works? Speculation: there is some kind of genetic/epigenetic signalling which modulates DNA repair mechanisms, such that certain DNA regions can be marked as more mutation-prone than others. And there may be selective pressure to make genes associated with disease-resistance more mutation-prone, because that’s a gene whose mutation is more likely to be beneficial (compensating mutations for evolution in existing diseases or to respond to new diseases), less likely to be harmful (most of the time, most likely outcome of the “wrong” mutation would be less resistance to diseases, but it probably wouldn’t otherwise be lethal or cause serious disability). But if that is what is actually going on here, is there any actual challenge to Darwin’s views? He didn’t know about DNA; I don’t think he ever claimed all mutations were equally likely (why would he when he had no idea what the actual mechanisms behind them were)

Re: Transgenerational Epigenetic Inheritance: the story of learned avoidance

#66

Post by rolph »

JumpCrisscross wrote: post #54
roughly wrote: post #35

Epigenetics is one of those things that seems wild until you pull the camera back a bit. A cell is affected by and responds to its surroundings - this is not controversial. In eukaryotes, this is usually done by way of altering gene expression - up- or down-regulation by means of chemical markers on the cell’s DNA which are created or removed by enzymes which are activated or deactivated by certain substances in the…

Does meiosis involve a reset mechanism of any kind?

no, no it does not strip protien complexes away from the DNA strand.

it involves a localized progression along the DNA surrounded by histones, and regulatory enzymes, displaced from proximity, until the replication fork zooms on through, and it all snaps back together.

the process is error prone, strands may cross over, chromosomes may fail to migrate properly.

Re: Transgenerational Epigenetic Inheritance: the story of learned avoidance

#67

Post by ggreer »

JumpCrisscross wrote: post #54
roughly wrote: post #35

Epigenetics is one of those things that seems wild until you pull the camera back a bit. A cell is affected by and responds to its surroundings - this is not controversial. In eukaryotes, this is usually done by way of altering gene expression - up- or down-regulation by means of chemical markers on the cell’s DNA which are created or removed by enzymes which are activated or deactivated by certain substances in the…

Does meiosis involve a reset mechanism of any kind?

The reset happens in the days following fertilization. Pretty much 100% of human DNA gets demethylated then.

Re: Transgenerational Epigenetic Inheritance: the story of learned avoidance

#68

Post by RobotToaster »

macleginn wrote: post #26
shevy-java wrote: post #8

So Lamarck wasn't entirely incorrect either. Darwin would have been fascinated by these results.

There has been aruably a more serious blow to the pure Darwinian evolution (this is all epigenetics, after all): non-random occurrence of useful mutations in populations exposed to particular diseases. https://pubmed.ncbi.nlm.nih.gov/40854136/

Lysenko wasn't entirely wrong then, crazy.

Re: Transgenerational Epigenetic Inheritance: the story of learned avoidance

#69

Post by ch4s3 »

macleginn wrote: post #36
ch4s3 wrote: post #28

Earlier quoted context omitted.

I don’t really see that as anti-Darwinian. Those genes successfully attach themselves to a new organism and provide advantages such that they are selected for in the population.

The selection is classical, but the mutations are supposed to be random, not skewed towards more useful genetic variants. One can speculate that a purely random (and otherwise neutral, say) prior mutation led to this directionality, but the actual resulting mechanism is AFAIK still unknown.

Natural selection has nothing to do with randomness per se, it’s merely differential selection based on environmental fitness. The fitness function of a given environment can even narrow a range of existing genes without any mutation occurring during the period where the new fitness function is applied. The classic example of this is peppered moths shifting toward the darker range of their preexisting color range during the Industrial Revolution.

Horizontal gene transfer is another way organisms can acquire new traits.

Post reply on HN