1. Two Pseudomonas strains isolated from soil metabolized 2,4-dichlorophenoxyacetate (2,4-D) as sole carbon source in mineral salts liquid medium. 2. 2,4-Dichlorophenoxyacetate cultures of Pseudomonas I (Smith, 1954) contained 2,4-dichlorophenol, 2-chlorophenol, 3,5-dichlorocatechol and alpha-chloromuconate, the last as a major metabolite. 3. Dechlorination at the 4(p)-position of the aromatic ring must therefore take place at some stages before ring fission. 4. Pseudomonas N.C.I.B. 9340 (Gaunt, 1962) cultures metabolizing 2,4-dichlorophenoxyacetate contained 2,4-dichloro-6-hydroxyphenoxyacetate, 2,4-dichlorophenol, 3,5-dichlorocatechol and an unstable compound, probably alphagamma-dichloromuconate. 5. Cell-free extracts of the latter organism grown in 2,4-dichlorophenoxyacetate cultures contained an oxygenase that converted 3,5-dichlorocatechol into alphagamma-dichloromuconate, a chlorolactonase that in the presence of Mn(2+) ions converted the dichloromuconate into gamma-carboxymethylene-alpha-chloro-Delta(alphabeta)-butenolide, and a delactonizing enzyme that gave alpha-chloromaleylacetate from this lactone. 6. Pathways of metabolism of 2,4-dichlorophenoxyacetate are discussed.

1. In a number of separate experiments, yeast RNA, mixtures of its constituent nucleosides, its constituent bases and ribose were administered orally to rats. In each instance, the resultant changes in the composition of body fluids were monitored using sensitive methods.2. Ingestion of RNA (100g/kg diet) caused detectable increases in intestinal ribose, inorganic phosphate, uridine, pseudouridine, uracil, inosine, uric acid and probably other purine bases. Their accumulation did not detectably affect the rate of passage of food along the digestive tract, even though some nucleosides are known to affect gut motility.3. Although plasma levels of uric acid and uridine were higher when RNA was administered in the diet, these changes were very slight compared with those in plasma uracil, which in some experiments were increased more than 20-fold compared with control levels (300μmol/l). Analysis of erythrocytes indicated that the internal environment of at least some cells of the body are similarly altered.4. Analyses indicated that all dietary RNA-phosphate passed into the urine from the gut but most of the RNA-ribose was probably metabolized. Uracil and uric acid levels in the urine reflected plasma composition.5. The effect of orally administered mixed nucleosides on blood and urine composition was similar to that of RNA, but the response to an equivalent mixture of free bases differed in several respects; cytosine, adenine and hypoxanthine appeared in urine only under these circumstances.

The counter-regulatory effect of adenosine, isoprenaline and selected cyclic AMP analogues on insulinstimulated 3-O-methylglucose transport and insulin binding were studied in rat fat-cells. Isoprenaline alone had no consistent effect on glucose transport in the presence of maximally effective insulin concentrations.However, it decreased insulin binding by approx. 20% and increased EC50 (concn. giving 50% of maximal stimulation) for insulin from 8 + 1 to 17 + 2 #sunits/ml. Adenosine deaminase (ADA) alone only exerted a slight effect, whereas isoprenaline and ADA in combination consistently decreased the maximal effect of insulin on glucose transport, decreased insulin binding by approx. 30% and markedly decreased insulinsensitivity (EC50 61 + 8 ,units/ml). In cells from pertussis-toxin-treated animals, isoprenaline alone decreased the insulin response by approx. 75%, decreased insulin binding by approx. 45% and caused a marked rightward shift in the dose-response curve for insulin (EC50 103 + 34 #sunits/ml). The importance of cyclic AMP for these effects was evaluated with the analogue M6-monobutyryl cyclic AMP, which is resistant to hydrolysis by the phosphodiesterase. The importance of phosphodiesterase activation by insulin was studied with 8-bromo cyclic AMP, which is an excellent substrate for this enzyme. N6-Monobutyryl cyclic AMP, in contrast with 8-bromo cyclic AMP, markedly impaired insulin-sensitivity (EC50 approx. 100,uunits/ml).However, the maximal effect of insulin was only slightly attenuated. In conclusion: (1) fl-adrenergic stimulation and cyclic AMP markedly alter insulin-sensitivity, but not responsiveness, mainly through post-receptor perturbations; (2) when cyclic AMP is increased phosphodiesterase activation by insulin is a critical step to elicit insulin action; (3) adenosine modulates the insulin-antagonistic effect of ,-adrenergic stimulation via Ni (inhibitory nucleotide-binding protein) through both cyclic-AMP-dependent and -independent mechanisms.

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