The regional distribution of poly (A) and total RNA concentrations during early Xenopus development.

Xenopus laevis embryos were oriented and sectioned into six regions along one of three axes: animal-vegetal, dorsal-ventral, or right-left. Total RNA (predominantly ribosomal RNA) and poly riboadenylate [poly (A)] were measured for each region during early embryogenesis. The concentrations of both total RNA and poly(A) are nonuniformly distributed during early development. Total RNA is approximately four-fold more concentrated in the more animal portions than the more vegetal portions of the embryo. The dorsal-most region contains a 1.5-fold higher concentration than in the other five regions of the four-celled embryo along the dorsal-ventral axis. Poly(A) concentrations show temporal and regional specific changes in concentration during early development with higher concentrations more generally found in the animal-most regions.