Transcription and polyadenylation processes during early development of quail embryo.

Transcription of tRNA and mRNA occurs in quail as early as during cleavage while rRNA transcription becomes measurable during blastulation. The polyadenylated fraction content is newly synthesized RNA amounting to 6% during cleavage and blastulation decreases to 3% during gastrulation. Up to 3/4 adenylic residues incorporated into RNA during cleavage are accumulated in the polyadenylated molecules mainly in the form of RNAse-resistant tracts.