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Dads Pass On More Than Genetics In Their Sperm (smithsonianmag.com)
According to two complementary studies, sperm change their cargo as they travel the reproductive tract, which can have consequences on the viability of future offspring. Smithsonian reports: The legacy of a dad's behavior can even live on in his child if his epigenetic elements enter an embryo. For instance, mice born to fathers that experience stress can inherit the behavioral consequences of traumatic memories. Additionally, mouse dads with less-than-desirable diets can pass a wonky metabolism onto their kids. Upasna Sharma and Colin Conine, both working under Oliver Rando, a professor of biochemistry at the University of Massachusetts Medical School, were some of the researchers to report such findings in 2016. In their work, Sharma and Conine noted that, in mice, while immature testicular sperm contain DNA identical to that of mature sperm, immature sperm relay different epigenetic information. It turns out that sperm small RNAs undergo post-testes turnover, picking up intel on the father's physical health (or lack thereof) after they're manufactured, but before they exit the body. However, the exact pit stop at which these additional small RNAs hitch a ride remained unknown.
To solve the mystery, Sharma, who led the first of the two new studies, decided to track the composition of small RNAs within mouse sperm as they fled the testes and cruised through the epididymis. She and her colleagues isolated sperm of several different ages from mice, including those about to emerge from the testes, those entering the early part of the epididymis and those in the late part of the epididymis. Sharma was surprised to find that many small RNAs seemed to be discarded or destroyed upon entering the early epididymis; then, the newly vacated sperm reacquired epigenetic intel that reflected the father's state of being, boasting a full set by the time they left the late epididymis. There was only one possible source for the small RNA reacquisition: the cells of the epididymis -- which meant that cells outside of the sperm were transmitting information into future generations. [...] Colin Conine, who led the second of the two new studies, next tested if using immature sperm would have noticeable effects on the offspring of mice. He and his colleagues extracted sperm from the testes, early epididymis and late epididymis and injected them into eggs. All three types of sperm were able to fertilize eggs. However, when Conine transferred the resulting embryos into mouse surrogates, none derived from early epididymal sperm -- the intermediate stage devoid of most small RNAs -- implanted in the uterus. The least and most mature sperm of the bunch were winners -- but somehow, those in the middle were burning out, even though all their genes were intact. The only other explanation was that the defect was temporary. If this was the case, then perhaps, if fed the right small RNAs, the early epididymal sperm could be rescued.
To solve the mystery, Sharma, who led the first of the two new studies, decided to track the composition of small RNAs within mouse sperm as they fled the testes and cruised through the epididymis. She and her colleagues isolated sperm of several different ages from mice, including those about to emerge from the testes, those entering the early part of the epididymis and those in the late part of the epididymis. Sharma was surprised to find that many small RNAs seemed to be discarded or destroyed upon entering the early epididymis; then, the newly vacated sperm reacquired epigenetic intel that reflected the father's state of being, boasting a full set by the time they left the late epididymis. There was only one possible source for the small RNA reacquisition: the cells of the epididymis -- which meant that cells outside of the sperm were transmitting information into future generations. [...] Colin Conine, who led the second of the two new studies, next tested if using immature sperm would have noticeable effects on the offspring of mice. He and his colleagues extracted sperm from the testes, early epididymis and late epididymis and injected them into eggs. All three types of sperm were able to fertilize eggs. However, when Conine transferred the resulting embryos into mouse surrogates, none derived from early epididymal sperm -- the intermediate stage devoid of most small RNAs -- implanted in the uterus. The least and most mature sperm of the bunch were winners -- but somehow, those in the middle were burning out, even though all their genes were intact. The only other explanation was that the defect was temporary. If this was the case, then perhaps, if fed the right small RNAs, the early epididymal sperm could be rescued.
Those that claim to have lived past lives, I've often though those were memories coded in our genetic material, passed on to try to help the survival of the species. Now recalling that you are a person from some bygone era isn't necessarily helping but I think it is a side effect of the innate instincts that are passed on from generation to generation in a lot of species.
Genetic memories are not actual memories.. I've understood that they're more like stress markers.. As in 'this guy experienced prolonged uncertainty and famine in his life'
Nope. Does not modify your genetic code but how it is expressed (proteins, RNA, ...). It just says that the initial condition are important i.e. the condition in which the gametes are produced. This is not really a surprise to any biologist. The effect seems to support some Lamarckism but the mechanism are purely Darwinist.