Sea urchin maternal mRNA classes with distinct development regulation.

Previous studies of newly synthesized proteins during early development in sea urchins have revealed several different patterns of synthesis that can be used to predict the existence of mRNA classes with distinct regulatory controls. We have identified clones for abundant maternal mRNAs that are actively translated during early development by screening a cDNA library prepared from polysomal poly(A)+RNA isolated from 2-cell stage (2-hour) Strongylocentrotus purpuratus embryos. Probes prepared from these cDNA clones and several previously characterized maternal mRNA cDNAs were used to compare relative levels of individual mRNAs in eggs and embryos and their translational status at various developmental stages.

'Unmasking' of stored maternal mRNAs and the activation of protein synthesis at fertilization in sea urchins.

The isolation and in vitro assay of maternal mRNPs has led to differing conclusions as to whether maternal mRNAs in sea urchin eggs are in a repressed or 'masked' form. To circumvent the problems involved with in vitro approaches, we have used an in vivo assay to determine if the availability of mRNA and/or components of the translational machinery are limiting protein synthesis in the unfertilized egg. This assay involves the use of a protein synthesis elongation inhibitor to create a situation in the egg in which there is excess translational machinery available to bind mRNA.

Counterproductive transcriptional and translational regulation of elongation factor 1-alpha synthesis during early development in sea urchins.

We have isolated a cDNA clone encoding elongation factor 1-alpha (EF1-alpha) and used probes prepared from this cDNA to measure levels of EF1-alpha transcripts during early development. We also determined the fraction of EF1-alpha transcripts in polysomes during this time period. Following the blastula stage there is a sharp increase in the amount of EF1-alpha mRNA.