Molecular markers in sea urchin development

Little is known of the molecular events regulating the determination of cell lineages in the early embryo. Recently, Robert Angerer and Eric Davidson have used molecular probes to approach these developmental problems in the sea urchin embryo Strongylocentrotus purpuratus. 1 Their work shows that a number of genes are expressed in a lineage-specific manner, long before morphological differentiation becomes apparent. In one case, the pattern of gene expression can be correlated with changes in cell surface properties and cell behaviour.