A non-ACC pathway for ethylene biosynthesis in Botrytis cinerea

Premature softening and tissue senescence occur in kiwifruit infected with Botrytis cinerea. While ethylene production is enhanced in infected fruit and B. cinerea produces ethylene on defined media in vitro the source of ethylene in this pathosystem is unclear. Ethylene production by B. cinerea was enhanced when methionine or ∝-keto-methylthiobutyric acid (KMBA) was added to a defined (modified Pratts) medium. Although 1-aminocyclopropane-1-carboxylic acid (ACC) did not stimulate ethylene production, ∝-aminooxyacetic acid (AOA) was inhibitory suggesting a role for a pyridoxal phosphate mediated enzyme reaction down stream from the methionine/KMBA stimulated ethylene biosynthetic pathway. Cobalt chloride (Co²⁺) was inhibitory, but after a 4-d lag period ethylene production from B. cinerea cultures containing methionine and Co²⁺ reached the same level as those without Co²⁺. [U ¹⁴C] methionine was converted to ¹⁴C-ethylene with high efficiency indicating that it is a direct precursor, while [2,3 ¹⁴C]-ACC did not yield radioactively labelled ethylene. These results suggest that the ethylene biosynthetic pathway in B. cinerea does not involve ACC as a precursor and that the enzyme responsible for synthesising ethylene is similar to, but different from, ACC oxidase from higher plants. The ethylene biosynthetic pathway in B. cinerea is yet to be determined.     

Evidence for ozone formation in human atherosclerotic arteries

Here, we report evidence for the production of ozone in human disease. Signature products unique to cholesterol ozonolysis are present within atherosclerotic tissue at the time of carotid endarterectomy, suggesting that ozone production occurred during lesion development. Furthermore, advanced atherosclerotic plaques generate ozone when the leukocytes within the diseased arteries are activated in vitro. The steroids produced by cholesterol ozonolysis cause effects that are thought to be critical to the pathogenesis of atherosclerosis, including cytotoxicity, lipid-loading in macrophages, and deformation of the apolipoprotein B-100 secondary structure. We propose the trivial designation "atheronals" for this previously unrecognized class of steroids.     

Protein synthesis in relation to fruit ripening

The relationship of protein synthesis to ripening of Bartlett pears was determined by investigating several parameters of ripening under conditions of steady-state or new protein synthesis. The investigations were directed at the question of dependency of ripening on the activity of newly synthesized or pre-existing proteins. It was found that protein synthesis is required for normal fruit ripening and the proteins synthesized early in the ripening process include enzymes required for ripening.¹⁴C-Phenylalanine was incorporated into fruit proteins, which were subsequently separated by acrylamide gel electrophoresis, of fruits at various stages of ripening. Fruit ripening and ethylene synthesis are inhibited when protein synthesis is blocked by treatment with cycloheximide at the early-climacteric stage. However, once ripening progresses beyond a certain stage ripening, but not protein synthesis, proceeds equally well in the presence or absence of cycloheximide indicating that the enzymes involved in ripening are synthesized soon after ripening has been initiated. Ethylene does not overcome cycloheximide inhibition of ripening or protein synthesis. It is concluded that normal ripening of pear fruits requires the coordinated synthesis of enzymes whose concentrations are limiting the rate of the various ripening reactions. The synthesis of these enzymes takes place for the most part during the early stage of ripening before marked physical changes become apparent in the tissue. Ethylene is required in physiologically active concentrations in order to initiate this ripening syndrome and can act only if protein synthesis is allowed to proceed. Without ethylene, fruits which otherwise are ready to ripen continue to synthesize those proteins for which capacity already exists.

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Zusammenfassung Die Beziehungen der Proteinsynthese zur Reifung von Bartlett-Birnen wurden durch Untersuchungen verschiedener Reifeparameter unter Bedingungen einer Gleichgewichts- oder Neu-Synthese von Proteinen bestimmt. Die Untersuchungen konzentrierten sich auf die Frage nach der Abhängigkeit der Reifung von der Aktivität neusynthetisierter oder bereits vorhandener Proteine. Man fand, dass für die normale Fruchtreife eine Proteinsynthese erforderlich ist und dass die Proteine, die im frühen Reifungsstadium synthetisiert werden, Enzyme einschliessen, die für die Reifung erforderlich sind.¹⁴C-Phenylalanin wurde in Fruchtproteine eingebaut, die dann aus Früchten in verschiedenen Reifestadien durch Acryl-Gel-Elektrophorese isoliert wurden. Fruchtreife und Äthylensynthese werden gehemmt, wenn die Proteinsynthese durch Behandlung mit Cycloheximid im früh-climacterischen Stadium blockiert wird. Überschreitet die Reifung, jedoch nicht die Proteinsynthese ein gewisses Stadium, so läuft sie gleich gut sowohl bei Anwesenheit als auch bei Abwesenheit von Cycloheximid ab, was darauf hindeutet, dass die an der Reifung beteiligten Enzyme bald nach dem Beginn der Reifungsperiode synthetisiert werden. Äthylen hebt die Cycloheximidbedingte Hemmung der Reifung oder der Proteinsynthese nicht auf. Das lässt den Schluss zu, dass die normale Reifung von Birnen die koordinierte Synthese von Enzymen erfordert, deren Konzentration den Grad der verschiedenen Reifungs-Reaktionen bestimmt. Die Synthese dieser Enzyme erfolgt hauptsächlich während der frühen Reifestadien, noch bevor stärkere physikalische Veränderungen in den Geweben auftreten. Äthylen ist in physiologisch aktiver Konzentration erforderlich, um dieses Reifungssyndrom auszulösen. Es kann jedoch nur wirksam werden, wenn eine Proteinsynthese erfolgen kann. Früchte, die ansonsten zur Reifung bereit sind, fahren bei Fehlen von Äthylen fort, solche Proteine zu synthetisieren, für die eine Kapazität bereits vorhanden ist.

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Resume La relation entre la synthèse des protéines et la maturation de poires Bartlett a été étudiée en examinant différents paramètres de la maturation dans des conditions où la synthèse protéinique est soit constante soit nouvelle. Le but de la recherche était de savoir si la maturation dépend de l'activité de protéines néo-formées ou pré-existantes. On a trouvé que la synthèse des protéines est indispensable pour une maturation normale du fruit. Les proteines, synthétisées dans le premier stade de la maturation, incluent les enzymes nécessaires pour ce processus. De la¹⁴C-phénylalanine a été incorporée dans les protéines du fruit à différents stades de maturation; ensuite ces protéines ont été séparées par électrophorèse sur gel d'acrylamide. Lorsque, au début du stade climactérique, la synthèse des protéines est bloquée par la cycloheximide, la maturation du fruit et la synthèse de l'éthylène sont inhibées. Cependant, lorsque la maturation dépasse un certain stade, elle se poursuit, sans protéosynthèse, aussi bien en présence qu'en absence de cycloheximide. Ces résultats indiquent que les enzymes nécessaires à la maturation sont synthétisés dès le début de la maturation. L'éthylène ne lève pas l'inhibition de la maturation ou de la synthèse des protéines provoquée par la cycloheximide. L'auteur conclut que la maturation normale des poires nécessite la synthèse coördonée des enzymes, dont la concentration limite la vitesse des différentes réactions de maturation. La synthèse de ces enzymes a lieu principalement au début de la maturation, avant que des changements physiques importants ne puissent être observés au niveau des tissus. Une concentration physiologiquement active d'éthylène est nécessaire pour déclancher ce syndrome de maturation mais elle ne peut agir que si la synthèse protéinique elle même est possible. Sans éthylène, les fruits normalement prêts à mûrir, continuent à synthétiser uniquement les proteines pour lesquelles existe déjà une capacité de synthèse.

     

Rat mammary gland differentiation in vitro in the absence of steroids

Mammary glands from several strains of immature female rats will form small lobules of alveoli when cultured in chemically defined media lacking steroid hormones but containing insulin and prolactin. The degree of lobulo-alveolar differentiation is increased if estradiol, progesterone, and aldosterone are also included in the culture media.     

Molecular modeling directed by an interfacial test apparatus for the evaluation of protein and polymer ingredient function in situ

A simplified apparatus is described that measures the damping of a suspended measuring device. The movement of the device (bob) is damped by the properties of the air-water surface adsorbed material. Its value lies in describing the surface chemomechanical properties of ingredients and excipients used in food, nutraceutical, cosmetic (cosmeceutical), and natural drug-food product formulations that traverse the food sciences. Two surfactants, two food and drug-grade polymers, and five naturally occurring food and serum proteins were tested and used to estimate and model interfacial viscoelasticity. Equilibration times of >15 min were found to give sufficiently stable interfaces for routine assessment. The viscoelasticity of the air-water interface was estimated with reference to model solutions. These model solutions and associated self-assembled interfacial nanostructured adsorbed layers were fabricated using a preliminary screening process with the aid of a specialized foaming apparatus ( C(300) values), surface tension measurements (23-73 mN/m), and referential surface shear and dilation experiments. The viscoelasticity measured as a percentage of surface damping ( D) of a pendulum was found to range from 1.0 to 22.4% across the samples tested, and this represented interfacial viscosities in the range of 0-4630 microNs/m. The technique can distinguish between interfacial compositions and positions itself as an easily accessible valuable addition to tensiometric and analytical biochemistry-based techniques.