Pathways of purine ribonucleotide catabolism in Ehrlich ascites tumor cells in vitro

Ehrlich ascites tumor cells incubated in vitro with adenine-14C catabolized up to 20% of the radioactive nucleotides which were formed, principally via dephosphorylation of inosinate and xanthylate, with small amounts of adenylate and guanylate broken down. Cells incubated with hypoxanthine-14C catabolized a much larger proportion of nucleotides, principally via dephosphorylation of inosinate and xanthylate; guanylate was also broken down. Catabolic products of guanine-14C in these cells were xanthine, which was formed directly from guanine, and guanosine which at least in part was formed via dephosphorylation of guanylate.

Intraspecific transduction in Staphylococcus epidermidis and interspecific transduction between Staphylococcus aureus and Staphylococcus epidermidis

Phages were isolated from Staphylococcus epidermidis after exposure of cultures to mitomycin C. Using certain of these phages, genes controlling resistance to novobiocin, streptomycin, and erythromycin and genes involved in the synthesis of adenine and riboflavin were transferred from donor to recipient strains of S. epidermidis. Interspecific transduction of the Novr marker was accomplished between S. epidermidis and S. aureus. Attempts to transfer penicillin resistance were not successful.

Evidence that adenosine triphosphate or a related nucleotide is the transmitter substance released by non-adrenergic inhibitory nerves in the gut

1. Stimulation of the vagal non-adrenergic inhibitory innervation caused the release of adenosine and inosine into vascular perfusates from the stomachs of guinea-pigs and toads.2. Stimulation of portions of Auerbach's plexus isolated from turkey gizzard caused the release of adenosine triphosphate (ATP), adenosine diphosphate (ADP) and adenosine monophosphate (AMP).3. ATP, added to solutions perfused through the toad stomach vasculature, was broken down to adenosine, inosine and adenine.4. Of a series of purine and pyrimidine derivatives tested for inhibitory activity on the guinea-pig isolated taenia coli, ATP and ADP were the most potent.5. ATP caused inhibition of twelve other gut preparations previously shown to contain non-adrenergic inhibitory nerves. The inhibitory action of ATP was not prevented by tetrodotoxin.6. Quinidine antagonized relaxations of the guinea-pig taenia coli caused by catecholamines or adrenergic nerve stimulation. Higher concentrations of quinidine antagonized relaxations caused by ATP or non-adrenergic inhibitory nerve stimulation.7. When tachyphylaxis to ATP had been produced in the rabbit ileum, there was a consistent depression of the responses to non-adrenergic inhibitory nerve stimulation but not of responses to adrenergic nerve stimulation.8. It is suggested that ATP or a related nucleotide is the transmitter substance released by the non-adrenergic inhibitory innervation of the gut.