Oocytes maternal mRNA

We turn now to determination of the anterior/posterior axis in the early fly embryo while it is still a syncytium. As in determination of the dorsal/ventral axis, specification of anterior/posterior cell fate begins during oogenesis. The initial asymmetry also involves so-called maternal mRNAs, which are produced by nurse cells and transported into the oocyte. In this case they become localized in discrete spatial domains (see Figure 15-14). For example, bicoid mRNA is trapped at the most anterior region, or anterior pole, of the early fly embryo (Figure 15-19). The anterior localization of... 

Svoboda P, et al. (2000). Selective reduction of dormant maternal mRNAs in mouse oocytes by RNA interference. Development. 127(19) 4147-4156. 

Maskin is a cytoplasmic polyadenylation element-binding protein-associated factor. Dormant state of maternal mRNAs in immature oocytes is maintained by an abortive interaction of this protein with the eukaryotic initiation factors 4E and 4G. Phosphorylation of maskin promotes the dissociation of this interaction, thereby allows the dormant mRNAs to be translated actively. Aurora phosphorylation of maskin is reported to be involved in protein synthesis in maturing clam and Xenopus oocytes and in centrosome-dep>endent microtubule assembly at mitosis (Kinoshita et al. 2005 Pascreau et al. 2005). 

After the mRNA has been transported into the cytoplasm it may be stored, or at least be unavailable for translation, for some time. The best example of this is found in amphibian and sea urchin oocytes, which accumulate substantial amounts of maternal mRNA s only trans-... 

The polyadenylation of c-mos mRNA in maturing oocytes is similar to that of other maternal RNAs that are accumulated during oocyte... 

Mature mRNA molecules vary in lifetime. Some last for hours or days. Among the latter are mRNAs of maternal origin that accumulate in oocytes and are utilized during the early stages of embryonic development. Other mRNAs, e.g., transcripts of the c-fos and c-myc proto-oncogene products, have half-lives of 30 Some mRNA molecules are... 

There are several possible causes which could affect the differential phenotypic expression of enzymes in early development- the maternal effect. Among these are (1) the stability of enzyme accumulated during oocyte maturation (2) the stability of mRNA s which code for the maternal subunits of enzyme (3) the comparatively early activation of maternal genes as opposed to paternal genes. 

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