Function of the <Emphasis Type="Italic">rel</Emphasis> Gene in <Emphasis Type="Italic">Escherichia coli</Emphasis>

Sokawa et al. suggest that rel^- strains of Escherichia coli possess abnormal protein synthesizing machinery, which cannot carry out normal protein synthesis when the supply of amino-acids is limited.     

“Pleiotypic Response”

A hypothesis has been developed to relate stringent control in bacteria to a set of interactions involved in the regulation of growth of transformed and untransformed mammalian cells.     

Inhibition of DNA Synthesis but not of Poly-dAT Synthesis by the Arabinose Analogue of Cytidine <Emphasis Type="Italic">in vitro</Emphasis>

Kimball and Wilson¹ reported that the arabinose analogue of cytidine (ara-C) inhibited DNA polymerase in a crude extract prepared from Ehrlich ascites cells. Furth and Cohen² observed cytosine arabinoside triphosphate (ara-CTP) inhibited DNA polymerase in extracts from either calf thymus or bovine lymphosarcoma tissue, although these investigators³ had already found no effect of ara-CTP on DNA polymerase from Escherichia coli. The inhibition in both of these cases could be substantially reversed by dCTP; but incorporation of the arabinose nucleotide (ara-CMP) into DNA could not be unequivocally demonstrated. Graham and Whitmore⁴ reported the incorporation of ara-C into DNA in vivo and the inhibition of a DNA polymerase from L cells by ara-CTP. They found that ara-CMP was initially incorporated into small DNA strands but subsequently appeared in long strands. Momparler⁵ has presented evidence that, in vitro, ara-C incorporation was limited to the 3′-hydroxyl end of DNA chains. Such incorporation might be expected to block further chain elongation but this expectation was not supported by the evidence presented by Graham and Whitmore.     

Endopeptidase Activity of Phage λ-Endolysin

JACOB and Fuerst^1,2 demonstrated the presence of a bacteriolytic enzyme (λ-endolysin) in the induced cultures of lysogenic Escherichia coli K12 (λ). The enzyme was later identified as the product of gene R; of phage λ³ which is involved in bacterial lysis at the end of a latent period. The enzyme is apt to form spheroplast-like structures in E. coli² and one would therefore expect its substrate to be murein.     

A new species of coccinellid feeding on scale insects in West Pakistan

Résumé Les auteurs décriventPseudoscymnus simmondsi, espèce nouvelle deCoccinellidae prédatrice dePinnaspis strachani (Cooley) surFicus palmata au Pakistan occidental. Les autres espèces du genre sont connues seulement de l'Extrême-Orient.

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This research has been financed in part by a grant made by the United States Department of Agriculture, Agricultural Research Service.     

Age-related changes in body weight,scrotal size and plasma testosterone levels in buffalo bulls (Bubalus bubalis)

Body weight, testicle size and peripheral testosterone concentrations were measured in 35 water buffalo bulls at 5, 15, 17, 21, 25 and 38 months of age. These parameters were studied in all animals during the same month (October), so the changes due to age were independent of changes in photoperiod and temperature. Body weight increased linearly with age. The testicular size measured in terms of scrotal circumference as related to age, showed a curvilinear increase; the average rate of testicular growth was maximum between 15 and 25 months. Plasma testosterone levels were low between 5 and 21 months. A significant rise in plasma concentration of testosterone was observed at 25 months reaching peak levels at 38 months. The mean age of sexually mature bulls at the time of first ejaculation of semen with motile sperm, was 24.9±0.9 months (n=9). It has been concluded that in the Nili-Ravi buffalo bulls the sexually quiescent period (prepubertal) extends up to 15 months of age and sexual maturation as indicated by the presence of motile sperm in the ejaculate is attained at about 25 months.     

Effect of soil acidity and saturating cation on adsorption of urea in soil

Summary Elevating the pH of two extremely acid tropical soils from an initial pH of 4 to 5 with Ca(OH)₂ and NaOH solutions resulted in a sharp decrease in urea adsorption. Further increases in pH to 9 caused only slight further decrease in urea adsorption. Ca treatment resulted in slightly higher adsorption than Na treatment over the full range of pH values studied for a clay soil with high smectite content, and for a loam with kaolinite mineralogy below pH 7. Above pH 7 a kaolinitic loamy soil gave slightly higher adsorption with Na treatment than with Ca.     

Note on breeding the argentine stem weevilHyperodes bonariensis [Col.: Curculionidae] and its egg parasitePatasson atomarius [Hym.: Mymaridae]

Hyperodes bonariensis Kuschel underwent ovarial diapause from March to August in the Bariloche area in Argentina. Feeding on germinating seedlings ofTriticum aestivum L. andPoa annua L. in continuous dark induced the weevil for oviposition in 24 and 32 days, respectively. Breeding techniques are described forH. bonariensis and its parasitePatasson atomarius (Brethes).