Catalase enhances damage to DNA by bleomycin-iron(II): the role of hydroxyl radicals

Bleomycin degrades DNA under aerobic conditions when a ferrous salt is added. This reaction is enhanced by catalase and certain hydroxyl radical scavengers but inhibited by the addition of hydrogen peroxide. A ferricbleomycin complex is, however, stimulated by addition of hydrogen peroxide. These findings suggest that catalase removes hydrogen peroxide and in so doing prevents loss of ferrous ions and formation of hydroxyl radicals (OH.) by a Fenton-type reaction. It further suggests that OH. radicals, when formed, are more involved in the inactivation of bleomycin than in the release of thiobarbituric acid reactive material from DNA.     

Bacillus thuringiensis and control of plant pests

Summary The feasibility ofB. thuringiensis as an economic insect control agent is dependent upon various factors. Consideration of three situations. whereB. thuringiensis could be used illustrates the interaction of these factors, and their contribution to determining the success or failure of the organism as an insecticide. Apple crops suffer from attack by a complex of insect pests, many of which are very susceptible to theB. thuringiensis toxin. However chemical control methods are preferred by growers in order to satisfy the consumers' demand for top quality blemish-free fruit. By contrast cotton growers are beset with problems of pest resistance to chemical insecticides. This problem is tackled by using pest management strategies which orchestrate all possible methods of control. Such a situation is ideally suited toB. thuringiensis products, but as yet they have proven to be of inadequate efficacy. The softwood forest industry is an example whereB. thuringiensis is both needed and effective. The pest complex is relatively simple, and there is public concern about the health risks of chemical sprays. Recent developments of high performance formulations means thatB. thuringiensis is an economic, cost-effective, biological alternative to chemical control for forestry pests.

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Resumen La posibilidad de utilizarB. thuringiensis para el control de insectos de una forma económica depende de varios factores. La consideración de tres situaciones distintas en las queB. thuringiensis puede ser utilizado ilustra la interacción de estos factores y su contribución al éxito o fracaso del organismo como insecticida. El cultivo de manzanas sufre el ataque de una serie de plagas de insectos, muchas de las cuales son susceptibles a la toxina deB. thuringiensis. Sin embargo, los agricultores prefieren utilizar métodos de control químico a fin de satisfacer la demanda del consumidor por un fruto de primera calidad sin marcas ni señales. Por el contrario, los cultivadores de algodon estan sensibilizados a los problemas de la aparición de plagas resistentes a los insecticidas químicos. Este problema se ha abordado utilizando sistemas de control integrado que aglutinan todos los posibles métodos de control. Esta situación parece la ideal para el uso de productos a base deB. thuringiensis, pero hasta ahora estos han resultado ser poco eficaces. La industria de la madera blanda constituye en ejemplo en el cualB. thuringiensis es a la vez necesario y efectivo. Las plagas en cuestión forman un sistema relativamente simple y los efectos de los sprays químicos sobre la salud pública son causa de preocupación. Los desarrollos recientes en formulaciones de elevada eficacia convierten aB. thuringiensis en una alternativa biológica económicamente factible frente al control químico de plagas forestales.

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Résumé La possibilité d'utiliser économiquementB. thuringiensis dans la lutte contre les insectes nuisibles dépend de facteurs divers. L'examen de trois situations dans lesquellesB. thuringiensis peut être utilisé illustre l'interaction de ces facteurs et leur contribution dans le succès ou l'échec de cet organisme comme insecticide. Les récoltes de pommes sont menacées par les attaques d'un mélange complexe d'insectes, dont beaucoup sont sensibles à la toxine deB. thuringiensis. Cependant, les horticulteurs préfèrent les méthodes chimiques à cause de l'exigence des consommateurs pour des fruits de haute qualité et sans aucune tache. Par contre, les cultivateurs de coton sont obsédés par les problèmes de résistance aux insecticides chimiques. Ce problème est affronté par des stratégies faisant appel à tous les moyens de lutte possibles. C'est une situation convenant bien aux produits qui contiennentB. thuringiensis, mais jusqu'ici ces produits se sont montrés inefficaces. L'industrie du bois tendre forestier est toutefois un exemple de cas oùB. thuringiensis est à la fois nécessaire et efficace. En effet, le complexe des insectes agressifs est relativement simple et il existe en outre une prévention du public contre les risques sanitaires des pulvérisations de produits chimiques. La mise au point récente de formulations à haute performance démontre queB. thuringiensis est, pour la lutte contre les insectes nuisibles des forêts, une alternative économique et bon-marché.

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Invited paper presented at the VII International Conference on the Global Impacts of Applied Microbiology, Helsiki, 12–16 August 1985. Session 8     

4-Hydroxy-2-Nonenal Levels Increase in the Plasma of Patients with Adult Respiratory Distress Syndrome as Linoleic Acid Appears to Fall

Gas chromatography-mass spectrometry has been applied to the analysis of plasma linoleic acid and one of its oxidation products, 4-hydroxy-2-nonenal (HNE), in adult patients with the acute respiratory distress syndrome (ARDS). Peak areas of total ion chromatograms showed there to be negative correlations between loss of linoleic acid and formation of HNE (measured by selective ion monitoring) in 7 out 10 patients studied. When HNE was quantitated by selective ion monitoring, with reference to a pure standard of HNE and an internal standard of nonanoic acid, ARDS patients showed significantly increased levels of HNE (0.412 ± 0.023 nmol/ml) compared with normal healthy controls (0.205 ± 0.018 nmol/ml).     

Efficient nuclear localization and immortalizing ability, two functions dependent on the adenovirus type 5 (Ad5) E1A second exon, are necessary for cotransformation with Ad5 E1B but not with T24ras.

Expression of adenovirus type 5 E1A 12S is sufficient to immortalize primary baby rat kidney cells, but another viral or cellular oncogene, such as E1B or T24ras, is necessary for complete transformation. The regions of 12S sufficient for T24ras cotransformation have been well characterized and are located in the first exon. The second exon is dispensable for ras cotransformation, although it contains a region which appears to modulate the transforming phenotype. The same 12S first exon regions important in ras transformation are also necessary for E1B transformation. Analysis of an extensive series of second exon deletion and amino acid point mutations demonstrated that mutations affecting either the efficient nuclear localization and/or the immortalizing ability of the 12S protein also prevented cooperation with E1B. In general, the entire C-terminal half of 12S, including the nuclear localization signal, was necessary for efficient cotransformation with E1B. In addition to the differences between T24ras and E1B regarding 12S regions necessary for cotransformation, the characteristics of E1B-cotransformed foci differed from those of T24ras. The E1B foci took longer to appear and had a much slower growth rate. No hypertransformed foci were produced with E1B cotransfections, and established E1A-E1B lines exhibited minimal growth in soft agar compared with that of E1A-T24ras lines.     

The intranuclear location of a herpes simplex virus DNA-binding protein is determined by the status of viral DNA replication

The herpes simplex viral DNA-binding protein, ICP8, is targeted to two different locations in the cell nucleus as part of its maturation pathway. Prior to viral DNA synthesis ICP8 was found at discrete pre-replicative sites throughout the nucleus, where it exhibited a high salt-labile association with the nuclear matrix. During viral DNA replication ICP8 was localized in randomly distributed replication compartments, where it is bound to viral DNA. Initiation of viral DNA replication caused the protein to move from the prereplicative sites to the replication compartments, while inhibition of replication caused movement in the opposite direction. In cells where viral DNA synthesis was proceeding, a minor population of ICP8 may also have been associated with the prereplicative sites. The prereplicative sites may serve as a nuclear reservoir for ICP8 not bound to replicating or progeny DNA.     

Hexose sugar transport activity in a mouse fibroblast cell line temperature sensitive for expression of the transformed phenotype

A temperature-sensitive mouse fibroblast cell line was used to examine the relationship between hexose sugar uptake rates and the control of cell growth. The cell line used (ts-H6-15) is a derivative of SV-3T3 cells, exhibiting a transformed phenotype at 32°C and a normal phenotype at 39°C. For cells actively growing at either temperature, a marked decrease in the rate of 3-0-methyl-D-glucose (3-0-MeG) transport is observed as cell population density increases. At all cell population densities tested, 3-0-MeG transport rates (at a common assay temperature) were greater in H6-15 cells grown at 32°C than at 39°C, with the enhancement being maximal at the lowest cell densities. The effect of low serum-arrest on H6-15 cells revealed that cells growing at 39°C arrest in G1, while cells at 32°C stop more randomly throughout their cycle. Under conditions of low serum-arrest the rate of 3-0-MeG transport remained as high as in actively growing cells at both 32°C and 39°C. However, 2-deoxyglucose uptake rates were growth state-dependent at 39°C, indicating perhaps metabolic as well as membrane-level control of sugar accumulation. These results further demonstrate that rates of hexose sugar transport by themselves are not always absolutely correlated with rates of cell proliferation and, thus, may not be reliable predictors of cell growth potential.