We compared the initiation specificities in vitro of deoxyribonucleic acid-dependent ribonucleic acid polymerases purified from two cyanobacteria, Fremyella diplosiphon and Anacystis nidulans, and from Escherichia coli. A restriction fragment made from lambda deoxyribonucleic acid was used as a template. The cyanobacterial and E. coli ribonucleic acid polymerases recognized the same lambda prom...

It is noteworthy that most of the recent observations concerning the structure of ribonucleic acid (1) are in agreement regarding the presence of an as yet unknown labile linkage or linkages in the molecule. The information that has brought the facts to light has been obtained mostly by the use of enzymic methods. By the use of the enzyme ribonuclease, Allen and Eiler (2) have been able to show...

Growth of Mycoplasma pneumoniae was completely prevented by 0.06 mug of actinomycin D/ml, and 0.00375 mug/ml caused 90% inhibition. It thus appears that M. pneumoniae is more susceptible to actinomycin D than previously reported. Low concentrations (0.019 mug/ml) of the antibiotic primarily inhibited ribonucleic acid synthesis and high concentrations (20 mug/ml) inhibited both ribonucleic and d...

The separation of liver ribonucleic acid and deoxyribonucleic acid from the associated protein material without hydrolysis can be accomplished by a salt-extraction procedure described by Barnum & Huseby (1950). This method, based on ribose recovery (Lowe & Rand, 1956; C. U. Lowe & P. R. Venkataraman, in preparation), yields 80% of the total ribonucleic acid of normal liver homogenate or cell fr...

1. The pyrophosphate-exchange reactions which are catalysed by rat-liver preparations and depend upon leucine or isoleucine are profoundly modified by 'soluble' ribonucleic acid and by changes in magnesium concentration. The preponderant influence is exerted by the terminal nucleotide sequence of the 'soluble' ribonucleic acid. Lysinedependent pyrophosphate exchange occurs only at relatively hi...