Fertilisation V Flashcards
(21 cards)
What is protected from demethylation?
Imprinted gene promoters
What RNA does the oocyte contain?
Maternally inherited RNA
What is translation in the one cell embryo regulated by?
polyadenylation
Is the sperm RNA transferred to the oocyte?
Not conclusive evidence that it is
What is the outcome of the polyA tail being added to maternal mRNA is short (40-80nt)?
Translation is limited
What is the outcome of a longer (250nt) polyA tail being added to the mRNA?
translation occurs
What is polyadenylation controlled by?
cytoplasmic polyadenylation element (CPE) in the 3’ UTR
What protein synthesis step does not occur in gametes?
Transcription
AMount of polyadenylation in eubacteria?
Not much
What is transcription regulated by in gamates?
histone and other chromatin modifications
When does embryonic gene activation occur in mice?
4 hrs of fertilisation
What are the transcriptional activators of embryonic gene activation?
oncoproteins, eg Erg, c-Myc
What happens if he transcriptional activators are inhibited?
Development is blocked
What are the waves of early embryonic transcription?
iEGA (immedite EGA), Minor EGA, major EGA
What is minor EGA?
may be a continuation of iEGA
Major EGA characteristics?
two-cell embryos (mouse), 4-8-cell embryos (human)
larger amplitude (greater -fold change) than iEGA
possibly different TF regulation than iEGA
When is the maternal mRNA degraded?
during and after one-cell stage
What kind of nuclei are in the one cell embryos?
male and female pronuclei
How is the one cell embryo diploid?
each pronucleus contains a haploid set of chromosomes (one from each parent)
What do the two pronuclei do?
converge, membranes breakdown and chromosomes
congregate (syngamy)
What is the one cell embryo developmentally?
totipotent: gives rise to entire organism
