Chapter 7- intro into gene imprinting (If food was scarce in slow growth…
Chapter 7- intro into gene imprinting
Lamarack's theory of evolution is prejudiced by scientists- although mostly wrong it could be a little right in certain cases.
Perhaps the reason research does not go into his theory is one scientist studying Lamarck killed himself and tainted the study of the theory.
Transgenerational inheritance evidence is seen in The Dutch Hunger Winter
Grandchildren were affected by malnourishment of their grandmothers- babies whose mothers were malnourished in their first three terms and gave birth to normal weight babies who were more likley to bcome obese gave birth to heavier babies
There are other reasons why this may be the case- epigenetics is just a theory..
Perhaps mother has epigenetic change which means more food is passed across placenta to baby- this is still transgenerational inheriatnce but not epigenetic as epigenoms is not inherited.
Maybe due to epeigenetic alterations, cytoplasm in female's egg caused baby to increase in weight. This is transgenertational inheritance but not inheritance of epigenetics.
If food was scarce in slow growth period (years leading up to puberty) offspring (sons and grandsons) of men had rreduced cardiovasuclar diease risk and is food was in abundance, risk was high.
This must be e[igenetic as no intra-unterine factors affect this and cytoplasm does not affect this
However this may not be the case as studies on human populations are not completely controlled by scientists so another factor may have caused this: correlation not causation.
Agouti mice were used by Professor Whitelaw to show transgenerational inheritance
Mice with light fur so unmethylated retrotransposon never gave birth to dark coloured mice and mice with methylated retortransposons gave birth to a stable ratio of mostl dark to in between and then light mice.
Professor Whitelaw repeated the experiment many times so it was very unlikley that she obtained her results by chance.
When these experiments were carried out, it was kniwn that food can affect Agouti mice fur colour- foods which are methyl group donord contributed to metyhlation changing fur colour.
By transplanting zygotes of dark coloured mice inrto light coloured mice, and vice versa it was shown that inly epigenetics were the cause of fur variation, not egg cell cytosplasm or epigenetic modification. This experiment only investigated mother to offspring patterns in fur.
Epigenetics and obesity
It has been shown that in rats given a diet with a high percentage of fat, offspring had genes to do with metabolism that were misregulated and and diabetes related abnormalities despite being born a normal weight.
Although this link has been found, it is not an excuse for people to say well it's my father's fault. If it a mouse's weight cannot be predicted in the controlled enviroment of a lab, there may be many possible ways that a human's DNA may be affected. Why not do everything that can be done to be healthy?
Experiments on mice showed that DNA methylation causing different fur colours had no effect on the colour of fur of offspring- offspring of make mice were always white (unmethylated DNA) regardless of the degree of methylation in their DNA.
Retrotransposons are transcribed to produce RNA
This can interfere with epigenetic factors so much so that IAP retrotransposons, a certain type, do not have their epigenetic modifications stripped even when fertilisation of gametes occur.
Retrotransposons are often switched off by methylation- probably an evolutionary solution to dangerous retrotransposons
Are all transposons bad? Research on evolution hypothesises DNA got epigenetics to repress parastiic DNA.