Inter- and Trans-intergenerational Epigenetics

Question 1

transgenerational inheritance?

Answer 1

only altered phenotypes occurring in the second (in the case of male transmission) or third (in the case of female transmission) generation after a trigger can truly be described as transgenerational inheritance.

Question 2

intergenerational inheritance?

Answer 2

Effects spanning shorter timescales are described as parental or intergenerational. Nonetheless, many described intergenerational effects share mechanisms with transgenerational effects.

Question 3

Mechanism of yeast psi- to psi+ convergence

Answer 3

prion aggregation of SUp35 leads to transition to psi+ yeast type which becomes conserved throughout all following generations

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Question 4

prion disease

Answer 4

Creuztfeld Jacob

Question 5

why yeast use prions

Answer 5

ast adaptation to a changing environment
* [PSI+] allows cells to occupy a new niche without foregoing their
capacity to occupy the old.
* if the new phenotype remains advantageous, the size of the growing
population increases the likelihood that mutations will arise to
eliminate stop codons that are relevant to the phenotype and require
[PSI+] for read-through.
* these would make that phenotype more robust and fix the trait; cells
would retain the phenotype upon reversion to the [psi-] state
* by this mechanism, [PSI+] could facilitate the evolution of new traits

Question 5

Examples of transgenerational inheritance

Answer 5

yeast prions,
corn transposons

Question 6

types of transposons

Answer 6

Retro, simple,

Question 7

spotted kernels

Answer 7

the Ds transposon has been inserted in the C gene -> purple. However, the corn is treated with Ac (activator)

Question 8

paramutation?

Answer 8

In epigenetics, a paramutation is an interaction between two alleles at a single locus, whereby one allele induces a heritable change in the other allele.[1] The change may be in the pattern of DNA methylation or histone modifications.[2] The allele inducing the change is said to be paramutagenic, while the allele that has been epigenetically altered is termed paramutable.

e.g. corn leaf color, petunia

Question 9

transgenerational effect on anthocyanin synthesis in petunia

Answer 9

CHS1 (Chalcone synthase) is being silenced through RNA interference (first discovery of RNAi in fact). As RNAi has a trans effect on the other chromosome it will stay on for a while aka transgenerational (even if CHS1 gene is added)

Question 10

difference in DNAm between us and plants

Answer 10

we have de novo methylation and complete DNAm erasure while in plants DNAm is being conserved throughout generations inherited and just partially erased. THis is related to their need for quicker adaptation to environmental changes (they cant walk)

Question 11

WHat happens if you add S-Adensyl Methionine to agouthi mice with brown spots

Answer 11

More brown bigger patches, the transposon element IAP that generally inhibits the agouthi gene is bing methylated at a higher level => more silenced IAP => more agouthi expression => more pigment. This feeding is INTERGENERATIONAL inherited phenotype as DNAm is erased. But as

Question 12

prions?

Answer 12

A prion is a protein that becomes misfolded and has the ability to transfer its
misfolded shape to the normal variants of the same protein.

Question 13

prion diseases in mammals

Answer 13

Scrapie in sheep and goats, bovine spongiform encephalophaty (BVE) in cows (‘mad
cow disease’).

Question 14

prion diseases in humans

Answer 14

Creutzfeldt-Jakob disease

Question 15

5-Aza

Answer 15

DNMT1 inhibitor