In vitro protein degradation measured by differential loss of labeled methionine and 3-methylhistidine: The effect of insulin

A new technique for studying the effect of insulin on protein degradation is reported. The method is based on measuring the parallel release of a reutilizable and a nonreutilizable amino acid from muscle protein. Animals are prelabeled in vivo with [Me-³H]methionine which labels both the nonreutilizable 3-methylhistidine and the reutilizable methionine of tissue protein. The data presented show that insulin has only a trivial effect on the loss of 3-methylhistidine from muscle protein, while it substantially diminishes the efflux of methionine. The analysis of muscle protein confirms the observation that insulin causes the reincorporation of methionine and has a minimum effect on the loss of 3-methylhistidine. This supports the view that the major inhibitory effect of insulin on gluconeogenesis is the diversion of the flow of amino acids away from the gluconeogenesis pathway back toward protein synthesis.     

A new streptomycete and a new polyene antibiotic,acmycin

A new antifungal antibiotic named acmycin was isolated from a soil streptomycete. Detailed comparative taxonomic studies showed that the organism differed from three related species of streptomycetes. The organism was referred to asStreptomyces sp. AC₂. The isolated antibiotic appears to be of polyene nature.     

Collagenolytic activity of a soil actinomycete

A soil actinomycete hydrolyzed collagen extracted from bovine Achilles tendon, calf skin, carp swim-bladder and rat tail tendon. Glucose, mannose, aspartic acid and asparagine increased its collagenolytic activity which was optimum at 28 °C and at pH 7.2 – 7.5. Metallic ions, NaEDTA, cysteine, 4-chloromercuribenzoate, glutathione and sodium azide were inhibitory.     

Glucosiduronidation and esterification of androsterone by human breast tumors invitro

The metabolism of ³H-androsterone was studied in homogenates (fortified with uridine 5'-diphosphoglucuronic acid and andenosine 3'-phosphate 5'-phosphosulfate) of eighteen breast tumors, one muscle underlying the primary breast carcinoma and metastatic axillary lymph nodes from a patient with suspected primary breast cancer. The major metabolites identified were less polar than androsterone. On saponification these lipoidal derivatives afforded androsterone as the only product (3 to 48%). Unmetabolized androsterone and lesser quantities of epiandrosterone, 5α-androstane-3α,17β-diol and 5α-androstane-3,17-dione comprised the free steroid fraction. Androsterone glucosiduronate was isolated (0.17–4.1%) from eight breast tumor homogenates and from the node tissue incubation (17%). There was no apparent correlation between glucuronyltransferase activity and histopathology or estrogen receptor content.     

Dryinid parasitoids of rice leafhoppers and planthoppers in the Philippines II. Rearing techniques

Three new techniques of rearing dryinids parasitising rice hoppers were developed, namely, laboratory rearing technique for detailed observations, device for transporting and rearing field-collected hoppers to estimate percentage parasitism and a breeding technique.

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Résumé Trois nouvelles techniques d’élevage de dryiinides parasites des cicadelles du riz ont été mises au point. L’une pour l’élevage en laboratoire en vue d’observations précises, un système pour le transport et l’élevage de cicadelles récoltées dans la nature afin d’évaluer le pourcentage de parasitisme et une technique d’élevage permanent.

     

Morphology,serology and biochemical characters of phage CVX-5, isolated from a patient with colitis

Electronmicroscopic observations indicate that bacteriophage CVX-5 has an angular head with long spiral tail which is noncontractile, possibly having 2--3 tail fibres attached at the distal part of the tail. This phage is antigenically unrelated to any of the T-phages. Inhibition of phage CVX-5 multiplication by mitomycin C and incorporation of 3H-thymidine into this phage indicate that phage CVX-5 is a DNA phage.