Abstract
Films of soluble ribonucleic acid (sRNA) and polyadenylic acid (poly-A) were used to investigate the distribution of nuclease activity in normal rat tissues. The reactions obtained with films of sRNA were similar to those previously observed with standard RNA and both substrates apparently reveal the same group of nucleases. On the other hand, the distribution of enzyme activity shown by films of poly-A differed markedly from that observed with RNA films, and it appears that films of poly-A demonstrate a different group of nucleases.