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.

     

Fertility of sows mated on different days of the week

The farrowing rates resulting from matings on different days of the week were determined for a 2800-sow intensive piggery in both 1983 and 1984. The results showed that sows mated early in the week achieved a significantly higher farrowing rate than sows mated late in the week (P less than 0.0001). During the seasonal (summer to autumn) infertility period, Wednesday matings resulted in a poor farrowing rate whereas for the rest of the year farrowing rates following Wednesday matings were similar to those for Sunday Monday and Tuesday matings. Consistent results were obtained for data from both years. It is proposed that the stress of regrouping unmated sows on Wednesday to accommodate newly weaned sows is responsible for this decrease in fertility. This study illustrates how detailed analysis of farrowing rates on a day of mating basis can identify a problem which is otherwise masked by weekly data.     

The comparative pathogenicity of four serovars of Actinobacillus (Haemophilus) pleuropneumoniae

The pathogenicity of 2 isolates of each of serovars 7, 3, 1 and 2 of Actinobacillus pleuropneumoniae was tested by intranasal inoculation into 60, 6-week-old large white pigs. Four dose rates varying from 0.27 to 560 x 10(6) organisms per pig with 10-fold serial dilutions were used. Surviving pigs were necropsied 7 days after inoculation. The proportion of pigs dying and developing gross lesions following infection was significantly greater for pigs given serotype 1 than for each of the other 3 serotypes, which did not differ significantly from each other. Twelve of 16 pigs given either of the 2 isolates of serovar 1 died after acute illness and 1 of 44 pigs given either of the 2 isolates each of serovars 7, 3 and 2 died. Pigs given serovar 1 showed high temperatures, severe respiratory distress, frothy haemorrhagic nasal discharge and weight loss. Lung lesions were produced in all 16 pigs given serovar 1, in 7 of 14 pigs given serovar 7, 7 of 14 pigs receiving serovar 3 and in 5 of 16 pigs given serovar 2. The lethal infections were characterised by a severe acute fibrinohaemorrhagic necrotising pleuropneumonia, whereas non-lethal cases had lung lesions ranging from necrotising purulent pleuropneumonia to abscessation. Significant differences between isolates in proportions of tissues culture positive for A. pleuropneumoniae for serovars 7 and 2, but not for serovars 3 and 1 suggested that isolates may vary in virulence within serovars, but more detailed studies are needed to clarify this point.     

Experimental evidence that tryptamine alkaloids do not cause Phalaris aquatica sudden death syndrome in sheep

The acute toxicity for sheep of 3 alkaloids that occur in Phalaris acquatica was examined by intravenous and oral administration. The lowest tested dose rates that produced clinically observed signs were, for 5-methoxy dimethyltryptamine, 0.1 mg/kg body weight intravenously and 40 mg/kg orally; for gramine, 10 mg/kg intravenously and 500 mg/kg orally; and for hordenine, 20 mg/kg intravenously and 800 mg/kg orally. All induced the clinical signs observed in the nervous form of phalaris toxicity, but none induced the cardiac, sudden death, syndrome.     

Severity and persistence of footrot in Merino sheep experimentally infected with a protease thermostable strain of Dichelobacter nodosus at five sites

Objective To test the hypothesis that ovine footrot associated with a thermostable protease strain of Dichelobacter nodosus undergoes self cure or is sustained as an annually recurring disease, depending on the environment.
Design and procedure Forty Merino sheep from a single blood line were infected with a protease thermostable strain of D nodosus a t each of five sites in Western Australia. Footrot lesions and microscopic evidence of D nodosus were recorded every fortnight for 2.5 years, supplemented by laboratory culture. Rainfall, soil and air temperature, pasture quantity and composition and soil types were also recorded. Flocks that apparently self cured were relocated to a more favourable site for footrot in the final spring season.
Results The maximum prevalence of feet with clinical footrot lesions was 80.6, 1.3, 14.4, 3.8 and 88.1% at the five sites. Severe footrot occurred for three consecutive spring seasons at one site that had clay loam soil and at least 3500 kg/ha total pasture dry matter annually. However, the infection was asymptomatic for up to 10 weeks between outbreaks. D nodosus was isolated from flocks for 2.5 years at only two sites, although there was microscopic evidence of the organism at other sites in the final year. A thermolabile variant (strain U6) of D nodosus was isolated from the two sites where footrot persisted.
Conclusion Depending on time and location, ovine footrot induced by a protease thermostable strain of D nodosus either self cured or persisted as annual outbreaks interspersed with periods of asymptomatic infection.     

Enhancement of cation diffusion rates across the 410-kilometer discontinuity in Earth's mantle

Rates of cation diffusion (magnesium, iron, and nickel) have been determined in olivine and its high-pressure polymorph, wadsleyite, at 9 to 15 gigapascals and 1100 degrees to 1400 degreesC for compositions that are relevant to Earth's mantle. Diffusion in olivine becomes strongly dependent on composition at high pressure. In wadsleyite, diffusion is one to two orders of magnitude faster than in olivine, depending on temperature. Homogenization of mantle heterogeneities (chemical mixing) and mineral transformations involving a magnesium-iron exchange will therefore occur considerably faster in the transition zone than at depths of less than 410 kilometers.     

Fertilisation and weed control effects on yield and weeds in durum wheat grown under rain-fed conditions in a Mediterranean climate

Summary A field study was undertaken to examine the effect of fertiliser type and weed control system on grain yield, yield components and weed population in durum wheat ( Triticum turgidum. var. durum) grown in a 4-year rotation [bare fallow–barley ( Hordeum vulgare )–vetch ( Vicia sativa )–wheat]. Fertilisation treatments were: no fertilisation, organic fertilisation with 2500 kg ha⁻¹ of compost (sheep manure and cereal straw) and chemical fertilisation with 100–60–60 kg ha⁻¹ of NPK. Weed-control treatments were: no control, herbicide, harrowing with long-flex spring tines and strip sowing with inter-row hoeing. Chemical fertilisation increased grain yield with respect to the other treatments, amongst which no significant differences were noted. Weed-control systems afforded no improvement in yield compared with controls; indeed, yields obtained using inter-row hoeing were lower. The weed population consisted of a large variety of species, of which the most important were Convolvulus arvensis and Polygonum aviculare . Application of weed-control systems reduced weed density. Herbicide was the most effective, reducing weed biomass by 80%, whilst harrowing and hoeing reduced weed biomass by 40% and 52% respectively. Inter-row hoeing does not appear to be a viable alternative to herbicides, when used as the sole weed control method in a non-diverse cropping system in Mediterranean climates. The lack of response to compost suggests a need for further long-term research.