Abstract
Polarized cortical mRNA determinants such as maternal macho-1 and pem-1 in ascidians, like budding yeast mating factor ASH1 reside on the cER-mRNA domain a subdomain of cortical Endoplasmic Reticulum(ER) and are translated in its vicinity. Using high resolution imaging and isolated cortical fragments prepared from eggs and embryos we now find that macho-1 and pem-1 RNAs co-localize with phospho-protein regulators of translation initiation (MnK/4EBP/S6K).Translation of cortical pem-1 RNA follows its bi-polarized relocalization. About 10. min after fertilization or artificial activation with a calcium ionophore, PEM1 protein is detected in the vegetal cortex in the vicinity of pem-1 RNA. About 40. min after fertilization-when pem-1 RNA and P-MnK move to the posterior pole-PEM1 protein remains in place forming a network of cortical patches anchored at the level of the zygote plasma membrane before disappearing. Cortical PEM1 protein is detected again at the 4 cell stage in the posterior centrosome attracting body (CAB) region where the cER-mRNA domain harboring pem-1/P-MnK/P-4EBP/P-S6K is concentrated. Bi-polarized PEM1 protein signals are not detected when pem-1 morpholinos are injected into eggs or zygotes or when MnK is inhibited. We propose that localized translation of the pem-1 RNA determinant is triggered by the fertilization/calcium wave and that the process is controlled by phospho-protein regulators of translation initiation co-localized with the RNA determinant on a sub-domain of the cortical Endoplasmic Reticulum.
Original language | English (US) |
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Pages (from-to) | 211-226 |
Number of pages | 16 |
Journal | Developmental biology |
Volume | 357 |
Issue number | 1 |
DOIs | |
State | Published - Sep 1 2011 |
Externally published | Yes |
Keywords
- Ascidian
- Cortex
- Determinant mRNA
- Endoplasmic reticulum
- Fertilization
- Translation initiation
ASJC Scopus subject areas
- Molecular Biology
- Developmental Biology
- Cell Biology