Developmental shifts in the synthesis of heterogeneous nuclear RNA classes in the sea urchin embryo.

Three molecular classes with different properties can be distinguished in the heterogeneous nuclear RNA (HnRNA) of sea urchin embryos. The relative proportions of these classes, which we have previously designated alpha, beta and gamma HnRNA, undergo marked changes during development from morula to early gastrula. Such changes suggest the existence of more than a single HnRNA function, as well as specific roles for different HnRNA classes in embryonic development.