The development of an assay to detect mRNAs that affect early development.

We have constructed an assay to identify developmental effects of injected RNA molecules. The RNA is injected into the animal pole region of a 2- to 8-cell embryo. At the blastula stage, the animal cap is removed and its development in isolation tested. In controls, only epidermis is produced, but several of the injected RNA preparations, though not all, also form dorsal and ventral mesoderm and nervous tissue. This assay should be suitable for selecting cDNA clones complementary to mRNAs that direct development.