We have a specific example
of epigenetic memory that is passed on, and we can see it in the microscope.
Now, a study by scientists at UC Santa Cruz shows
how epigenetic memory can be passed across generations and from cell to cell during development.
«Using fertilized mouse eggs, we showed that the egg cell actively triggers demethylation of the paternal DNA — in other words, it initiates epigenetic reprogramming by stripping any
previous epigenetic memory passed on from the father.
For instance, malnutrition in early life as a result of poor nutrition during pregnancy and / or the lactation period may be stored on the offspring genome
as epigenetic memory and persist into adulthood, thereby increasing the susceptibility to metabolic diseases such as obesity in later life.
Utilising both chondrocytes as a starting material and non-integrating mRNA technology as a reprogramming strategy, the group aimed to remove the risk
of epigenetic memory of somatic cell of origin, which can affect future differentiation propensity, and reduces the risk of abnormalities being introduced during reprogramming.
«
How epigenetic memory is passed through generations: Sperm and eggs transmit memory of gene repression to embryos.»
«We began with stem cells taken from cord - blood, which have fewer acquired mutations and little, if any,
epigenetic memory, which cells accumulate as time goes on,» says Zambidis, associate professor of oncology and pediatrics at the Johns Hopkins Institute for Cell Engineering and the Kimmel Cancer Center.
The incoming paternal DNA contains modifications that facilitate an «
epigenetic memory» of its sperm state.
«Fertilized egg cells trigger, monitor loss of sperm's
epigenetic memory.»
«We propose that Fgf21 methylation represents a form of
epigenetic memory that persists into adulthood, and it may have a role in the developmental programming of obesity.»
The study proves that mother's
epigenetic memory is essential for the development and survival of the new generation.
Other influences of external stimuli like stress, disease or diet are also supposed to be stored in
the epigenetic memory of cells.
But when the tissues of the next generation were tested, they had differentially expressed genes — clear signs of
epigenetic memory — even though they themselves had never experienced a hot spell.
After fertilization, maternal and paternal genomes erase some of
the epigenetic memory of the previously differentiated states in order to facilitate the beginning of new life as the zygote.
[RNA] could be critical in maintaining
this epigenetic memory during development,» he says, «although we are still in our infancy in understanding this phenomenon.»
• Do iPSCs created in this manner still retain an «
epigenetic memory» which may affect differentiation propensities?
Recent experiments on roundworms have shown that
epigenetic memories can be passed through generations for much longer than previously believed.
They also found that repetitive parts of the normal worm genome that look similar to the transgene arrays also behaved in the same way, suggesting that
this epigenetic memory transfer was not restricted just to the artificially engineered genes.
Human skeletal muscles have
an epigenetic memory of earlier encounters with growth, according to a Keele University - led study.
I began to think of the tortoise in relation to the idea of
epigenetic memory (the accumulation of an individual's mental memory throughout their life) and epiphylogenetic memory (the inscription of memory onto objects).