Maternal mRNAComments

Maternal mRNA

The oocyte prepares massive quantities of mRNA by performing intensely synthesizing mRNA for a long period of time (even months) and by creating a more stable mRNA environment than in somatic cells.

Maternal mRNA Importance

EnucleationAn urchin blastomere underwent centrifugal enucleation, forming one nucleated and one enucleated blastomere.
DevelopmentEnucleated blastomere gets to blastula stage before arresting. Nucleated blastomere develops normally.
Other SpeciesSame outcome via centrifugal or chemical enucleation in many other organisms (except mammals).
ConclusionsEmbryonic transcription is not needed until the blastula stage in many species (except mammals). However, translation is necessary since puromycin (a translation inhibitor) stops development before the first cleavage.

Control of maternal mRNAs?

LocalizationExample: bicoid mRNA in the Drosophila embryo. The mRNA is bound to the cytoskeleton, primarily microtubles (proven by treating with certain microtubule-inhibiting chemicals). Specific gene products are required for localization. The mRNAs and proteins are transported along microtubules.
TranslationHow is translation of specific mRNAs and of total mRNA controlled? Example: bcd mRNA translation is activated at fertilization. Specific proteins bind its 3' UTR and repress translation until fertilization.