Antibiotic U-20,661 was shown to inhibit predominantly deoxyribonucleic acid (DNA)-directed ribonucleic acid (RNA) synthesis by binding to the double-stranded DNA template. Specific binding to DNA was verified by difference spectroscopy, reversal of the RNA polymerase inhibitory effect by increasing concentrations of DNA template, and by moderately increasing the melting temperature of double-s...

Antibiotic U-24,544, a new antibacterial agent, was found to be an effective uncoupler of phosphorylation associated with the oxidation of glutamate and succinate in rat liver mitochondria. Respiration was inhibited during glutamate oxidation but not during succinate oxidation. In a medium deficient in inorganic phosphate, the agent showed slight stimulation of mitochondrial glutamate oxidation...

Since the discovery (Soulier and Gueguen, 1947) that phenylindanedione (P.I.D.) was an anticoagulant which effectively altered the one-stage prothrombin time it has been used extensively in the treatment of cases of thrombosis (Blaustein, 1950; Blaustein, Shnayerson, and Wallach, 1953; Dennis, Coon, Hodgson, and Duff, 1952; Toohey, 1953). Clinically it appears to produce the same effect as dico...

Colicin A acting on sensitive cells of Escherichia coli inhibits a number of energy-requiring cellular functions. It appears to act similarly to colicins E1 and K.

The mode of action of cryomycin upon Staphylococcus aureus IFO 3061 and Bacillus subtilis IFO 3037 has been investigated. Cryomycin inhibited the syntheses of protein, RNAand DNAto almost the same degree. It caused a rapid increase of endogenous and exogenous respiration in the test organisms at minimumgrowth inhibitory concentrations. It was concluded that the primary effect of cryomycin was o...

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In a preceding paper it was shown that low concentrations of diphtheria toxin, in the presence of NAD 1 as an essential cofactor, inhibit the incorporation of amino acids into TCA-precipitable peptides in mammalian cell extracts (1). Collier (2) has demonstrated that this inhibitory action of the toxin is due to the specific inactivation of transferase II , one of the highly labile soluble enzy...

It has been shown that the gestagen component of oral contraceptives changes the composition of the cervical mucus so as to make sperm penetration difficult. Endometrial changes and changes in the normal patterns of tubal and uterine motility have been described. Ovulation is inhibited by inhibition of ovarian response to gonadotrophins or by inhibition of the formation and/or release of endo...

The blood and tissues of most insects contain tyrosinase, together with a suitable substrate. When blood is shed or the tissues damaged, enzyme and substrate react and eventually produce melanin; why do they not react in the intact animal? The oldest theory was that they were held apart by some structural organization of the cytoplasm and that they only came together when this was destroyed. Th...