DEVELOPMENTAL BIOLOGY 153,402-406 (1992) Histone H2A.F/Z mRNA Is Stored in the Egg Cytoplasm and Basally Regulated in the Sea Urchin Embryo

The sea urchin H2A.F/Z histone is a member of a subclass of highly conserved H2A variants. Sequence analysis confirms that HZA.F/Z mRNA is polgadenglated. 17 ~ sifu hybridization studies demonstrate that maternal H2A.F/Z message is stored in the egg cytoplasm and present at equal levels in all cells of the mesenchyme blastula-stage embryo, suggesting that HBA.F/Z is not coordinately regulated with DNA synthesis. When blastula-stage embryos were exposed to DNA synthesis inhibitors, no effect on the steady-state level of HZA.F/Z mRNA was observed, while the level of late class H2B mRNA decreased substantially. These results provide evidence that the basal mode of regulation of this unusual histone variant is conserved evolutionarily. 8s.) 1992 Academic press, I~C