Sea-urchin RNAs displaying differences in developmental regulation and in complementarity to a collagen exon probe.

Sea-urchin embryo RNAs of 9 kb and 7 kb hybridise with a collagen-coding probe. The delta Tm of the hybrids indicates a 70% sequence identity between these RNA regions. Both RNAs are localised in the pluteus endomesoderm, but accumulate over different developmental periods: the 9 kb RNA first appears in the blastula and reaches a maximum concentration during the gastrula stages, while the 7 kb RNA is first detected in the gastrula and is at maximal concentration in the pluteus larva. Animalization by transient exposure of the early stage embryo to Zn2+ alters the developmental profile of the 9 kb collagen mRNA in a way that is clearly different from responses of other mRNAs whose accumulations are initiated during the blastula stage (Nemer, M. (1986) Dev. Biol. 114, 214-224).