Subcellular Localization of Maternal Histone mRNAs and the Control of Histone Synthesis in the Sea Urchin Embryo
Early α-subtype histone synthesis in the sea urchin embryo occurs using stored naturally synthesized mRNA. Embryonic α-subtype histone mRNAs do not appear until the 16-cell stage. We have examined these maternal α histone mRNAs and demonstrate that, unlike the bulk of maternal mRNAs, they are recruited into polysomes and translated after a 90-min to 2-hr delay following fertilization. Using cell fractionation procedures and in situ autoradiography, we further demonstrate that maternal α histone mRNAs are sequestered within the pronucleus of the mature egg. Appearance of α-subtype histone mRNAs in the polysomes of the zygote correlates with the dissociation of the nuclear envelope prior to first cleavage.
KeywordsHistone mRNAs Maternal mRNAs Nuclear Envelope Breakdown Histone Gene Expression Histone Synthesis
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