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Acquired Characteristics May Be Inheritable
A story from a week or so back in Technology Review describes research coming to the surprising conclusion that Jean-Baptiste Lamarck may have been right — that acquired characteristics can be passed on to offspring, at least in rodents. Lamarck's ideas have been controversial for 200 years, and dismissed in mainstream scientific thinking for nearly that long. "In Feig's study, mice genetically engineered to have memory problems were raised in an enriched environment — given toys, exercise, and social interaction — for two weeks during adolescence. The animals' memory improved... The mice were then returned to normal conditions, where they grew up and had offspring. This next generation of mice also had better memory, despite having the genetic defect and never having been exposed to the enriched environment."
Lamarck is one of those guys who's name is generally synonymous with bad science (he's about as villified as Darwin is deified). I'm actually a bit (pleasantly) surprised that someone would invest the time into this sort of study.
That being said, the article is rather short in one important area: a suggested mechanism for this sort of inheritance. Without that, it's bound to be mired in controversy for some time.
Here's the actual article.
We're just learning that Histone/DNA modifications can be inherited.
Histones (the spools around which DNA is stored) tell when the DNA source code should be 'active' vs 'inactive'. And these histones have a huge data space in the form of possible modifications (methylation, acetylation, etc.).
When DNA is replicated, these histones too are replicated at the same time. And they seem to be replicated in a semiconserved manner similar to DNA (half go to 'old' strand, half go to 'new' strand). And that there is a whole series of touring-like proteins that can 'read' 'write' or 'erase' these modifications.
If these modifications are made during an organism's life, they can be inherited by offspring.
Not only is the code being copied, but the 'marks' that tell which/when/where to read the code at any given time/condition too can be passed down. And that these marks can be written in real time rather than waiting for mutations in the code itself.
There was a recent study that XO females who inherited the X from their father had markedly different dispositions than those who inherited the X from their mother. DNA modification that is unique to how the male or female deal with their own X chromosome could be being passed down to offspring.
Many genes are only activated in the presence of certain helper chemicals. Similarly, some proteins can only fold properly with the assistance of helper enzymes. Some of these helper systems form a loop and are kickstarted by the uterine environment.
If you disrupt one of those loops by injecting hormones or other methods of altering body chemistry, like scaring the living shit of a mouse at an early age, the cycle will break and thus affect the uterine environment and not kickstart the next mouse's production of those chemicals.
I could've sworn it had already been shown that pumping adrenaline into young female mice caused them to be adrenaline-sensitive and their progeny to be maternal inheritably adrenaline sensitive, but I can't find a link for it.
This was a common misconception until recently. You can read about it here.