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Adenovirus-specific nuclear and polysomal RNA, both early and late in the infectious cycle, contain a covalently linked region of polyadenylic acid 150-250 nucleotides long. A large proportion of the adenovirus-specific messenger RNA contains poly(A). As revealed by hybridization experiments, the poly(A) is not transcribed from adenovirus DNA. Furthermore, an adenosine analogue, cordycepin, blocks the synthesis of poly(A) and also inhibits the accumulation of adenovirus messenger RNA on polysomes. Addition of poly(A) to viral RNA may involve a host-controlled mechanism that regulates the processing and transport of messenger RNA.

Two kinds of phenotypic expression in purine biosynthesis result from recessive mutation to adel2 in baker's yeast. The mutants are adenine-specific, blocked in the conversion of inosine 5'-phosphate to adenylosuccinic acid; their response to inhibition of pathway activity by adenine is considerably reduced. Allelic partial reversions can restore prototrophy without correcting the regulatory defect imparted by the primary mutation. The separation of the two properties of the locus by allelic mutation supports the hypothesis that the locus specifies a protein of two independent functions, enzymatic and regulatory.

1. The intracellular cysteine and glutathione concentrations were measured in Escherichia coli under a variety of growth conditions. 2. An inverse relation between intracellular cysteine concentration and the specific activity of the sulphate-activating enzymes was found. 3. This is compatible with the view that the intracellular cysteine concentration controls the rate of synthesis of these enzymes.

1. The enzymic activation of sulphate by various tissue extracts of vitamin A-deficient rats and their pair-fed controls was studied. 2. Vitamin A deficiency does not impair the enzymic activity in liver, colon and brain. However, a significant decrease in activity was observed in epiphyseal cartilage.