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0:00
My name is John Torday.
I'm a Professor of Evolutionary
Medicine at UCLA.
This is a lecture
in a lecture series entitled
"Evolutionary Physiology".
This lecture is entitled
"The Unicellular State
as the Level
of Selection-Epigenetics".
0:16
It had long been thought
that epigenetic marks
that are acquired
during the life cycle
by the ovaries and testes,
DNA methylation, ubiquitination,
phosphorylation,
acetylation, ribosylation
were erased during meiosis.
It is now known that some
of those marks are retained
during meiosis
and further tested
for their functional fidelity,
during embryogenesis
and during the life cycle
of the organism.
0:42
Inheritance of epigenetic marks
can occur via the germline,
shown on the right.
Or via effects
of the environment
on hypothalamic DNA methylation
affecting maternal behavior,
being passed onto the next
several generations.
0:57
For example,
an odorant in the environment
can methylate sperm cells
causing a startle response
in the offspring.
1:06
Similarly, it has been shown
that a physiologic stress
to the pregnant mother rat
can be passed
on transgenerationally
due to epigenetic modification
of both somatic and germ cells.
1:17
There are several ways
in which epigenetic marks
are generated
to modify DNA readout.
Methylation, acetylation,
phosphorylation,
and ubiquitination
are all depicted in this slide.
1:30
Only about 3% of human
genetic disease is Mendelian.
Therefore, 97% of human
genetic disease is epigenetic.
Epigenetic inheritance affects
the offspring, not the adults.
The significance
of this to evolution theory
is that it represents
Lamarckian inheritance.
