Beziehungen zwischen Kohlenstoff-und Stickstoffmetabolismus bei Pflanzen — eine Übersicht über ausgewählte Aspekte

Zusammenfassung Die mannigfaltigen Wechselbeziehungen zwischen photosynthetischer Kohlenstoffassimilation und N-Metabolismus haben weltweit eine Vielzahl von Untersuchungen stimuliert. Es ist versucht worden, zu einigen ausgewählten Aspekten dieses komplexen Problemkreises eine Übersicht über den gegenwärtigen Kenntnisstand zu geben. Von den Prozessen auf molekularer Ebene wurden besonders der photorespiratorische N-Zyklus und die Beziehungen zwischen Photosynthese und Nitratassimilation berücksichtigt. Auf der organismischen Ebene spielen Wechselwirkungen zwischen Photosynthese und N-Haushalt in bezug auf die Ertragsbildung eine besondere Rolle. Sie wurden am Beispiel des Getreides erörtert. Mathematische Modelle der Photosynthese und Ertragsbildung haben in stärkerem Maße als bisher dem Einfluß des N-Metabolismus Rechnung zu tragen. Daher wurde der Darstellung dieses Problemkreises besondere Aufmerksamkeit gewidmet.

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Interactions between carbon and nitrogen metabolism in plants — a review of some selected topics

Summary The multiple interactions between photosynthetic carbon assimilation and nitrogen metabolism have stimulated worldwide investigations. In the present review some selected topics of this field are discussed. At the molecular level the photo-respiratory nitrogen cycle and relationships between photosynthesis and nitrate assimilation are especially considered. At the whole plant level relationships between photosynthesis and N metabolism are of importance with regard to yield formation of cultivated plants. As an example the situation in cereals is discussed. Mathematical models of photosynthesis and yield formation have to consider the influence of nitrogen metabolism on these processes. Therefore this aspect was treated in some detail.

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Statistical aspects of efficacy evaluation of plant protection products in field trials – a comment on EPPO Standard PP1/152

The evaluation of plant protection product efficacy in field trials is a complex task. Several aspects of the statistical evaluation are discussed in this paper, along with a recommendation to modify EPPO Standard PP1/152. Confidence intervals should be preferred over significance tests to avoid contradictions between 'statistical significance' and 'biological relevance'. Efficacy should first be demonstrated, by comparison of a new product with a well chosen reference product, using a test of non-inferiority. When non-inferiority has been established, a test of superiority can follow. Both can simply be obtained by one-sided confidence intervals of µ_Reference – µ_Product or µ_Reference / µ_Product, where µ_Reference and µ_Product are the means for the reference and the product, respectively. Confidence intervals for the ratio are easier to interpret because of the definition of percentage change. The evaluation that a trial is realistic and coherent should be performed according to the present EPPO guideline before any analysis of efficacy is made. Efficacy data from trial series should be preferred over individual trials because this represents different sites and increased sample size (number of sites and number of plots). The treatments-by-sites interaction should be modelled as a random effect in a mixed model. Software in R is available for these suggested analyses.     

Procoagulant activity in respiratory tract secretions from horses with chronic pulmonary disease

Cell-free supernatants (sol phases), obtained after centrifugation (50,000 x g for 45 minutes) of respiratory tract secretions from horses with chronic pulmonary disease, were assayed for procoagulant activity (PCA) in a one-stage clotting assay. Of the 103 specimens tested, 59% (61) contained PCA. Procoagulant activity was detected most often in respiratory tract secretions of severely affected horses and was correlated with the quantity of neutrophils in the respiratory tract secretions. In 12 of the 17 secretions tested, the clotting time was decreased in a dose-dependent manner. However, in the coagulation assay, some reversal of PCA or inhibition of coagulation was observed in 4 secretion specimens when greater volumes of sol phase were added. Procoagulant activity was characterized tentatively as tissue factor, because it was temperature stable and was inhibited by phospholipase C and by concanavalin A. Clotting was induced in factor VIII-deficient human plasma; however, with the exception of 1 respiratory secretion specimen, clotting was not enhanced in factor VII-deficient human plasma. Procoagulant activity is a useful indicator of airway inflammation.     

Measurement of temperature generation in the corium of bovine claws during claw trimming with an angle grinder using different grinding and cutting disks

On 80 bovine hindclaws from slaughtered cows a correct functional claw trimming (sole horn thickness 5 mm; group 1) and on further 80 hindclaws a standardised, incorrect claw trimming (sole horn thickness 2 mm; group 2) was performed using 4 different disks (one cutting, three grinding disks). Two thermocouples were inserted into the solar corium and the heat production on the corium was measured during claw trimming. During correct functional claw trimming with each of the 4 disks a temperature increase in the corium with a median of < or = 0.3 degrees C was calculated. During incorrect claw trimming (2 mm sole horn thickness) a temperature increase with a median of < or = 0.3 degrees C for the first three disks was determined. During claw trimming using the abrasive semiflexible plastic disk a median of 1.3 degrees C temperature increase was calculated. Comparison of the temperatures measured in the claws from group 1 and 2 showed a statistically significant difference between all four disks. Comparison of the temperature increase within each group (group 1 and 2) revealed a statistically significant difference between the cutting disk with steel blades and the abrasive, semiflexible plastic disk in both groups. The highest temperatures measured were 41.5 degrees C in group 1 using the disk with 70% amount of fitted hard metal granulate, and 42.2 degrees C in group 2 (temperature increase of 10.6 degrees C) using the abrasive semiflexible plastic disk. Under the experimental conditions of this study, only a very slight thermogenesis was found when a functional and correct claw trimming using the 4 tested disks was performed. This slight thermogenesis should not be able to cause thermic injury of the corium. By trimming the sole horn incorrectly (2 mm) the measured heat generation in the corium was minor, without danger of thermic insult, excepted for using the disk with a 70% amount of fitted hard metal granulate and the abrasive semiflexible plastic disk. Even, it is unlikely that a short term temperature increase of 10.6 degrees C can cause thermic insults of the solar corium.     

Comparative genetic characterization of Porcine Circovirus type 2 samples from German wild boar populations

PCV-2 is involved in "postweaning multisystemic wasting syndrome" (PMWS), "porcine dermatitis and nephropathy syndrome" (PDNS), respiratory and reproductive disorders, and thereby plays a crucial role in today's swine production world-wide. The virus is apparently ubiquitous in domestic pigs and has also been demonstrated in wild pigs. Up to now, a characterization of PCV-2 samples from wild pigs, which might help to estimate the possible role of wild pigs as sources of domestic pig infection, has not been carried out. Spleen samples from 16 PCV-2-positive wild pigs from hunting grounds of four regions in Germany were used for the analysis of the viral genome. In one sample, the complete sequence of the genome was determined. In the other, a 742 nucleotide fragment from the highly variable capsid sequence of the ORF2 was sequenced. Analysis of the sequences led to the identification of three PCV-2 strains. One strain, representing 14 of the 16 samples, was closely related with Chinese, but not with German strains. The genome of this strain was shortened by one nucleotide by a deletion close to the end of ORF2. The deletion led to a shift of the stop-codon and to the insertion of a further codon. Two further strains differed in up to 4.7% of nucleotides and up to 10.5% of amino acids (aa). These strains were aligned with clusters of PCV-2 samples from mainly French and German domestic origin.     

Interferon-gamma response of PBMC indicates productive pseudorabies virus (PRV) infection in swine

In Chinese Meishan/German Landrace cross-bred swine F2 generation interferon gamma (IFN-gamma) production by peripheral blood mononuclear cells (PBMC) was determined directly ex vivo at different time points after survival of a virulent pseudorabies virus (PRV) infection. This reactivity was compared with the reactivity of na?ve PBMC. Significant IFN-gamma production was determined in ELISA and ELISPOT only after in vitro PBMC re-stimulation with PRV and not with the closely related bovine herpesvirus BHV-1. The PRV-specific IFN-gamma secretion from re-stimulated PBMC showed high levels 6 days after infection, before the presence of serum antibodies, and it persisted at a high level over a 3 months period. The response of a group of eight piglets infected intranasally with PRV varied. Only two animals showed the expected typical fever response. PRV specific IFN-gamma production by PBMC clearly indicated that infection had occurred. Early significant IFN-gamma production by primed PBMC turned out to be a reliable and specific ex vivo marker for cellular response against productive PRV infection in swine before antibody formation.     

Feline caries in two cats from a 13th century archeological excavation

Mandibles of two cats containing carious lesions were discovered among the previously published findings of feline dental resorptive lesions from materials examined at an archaeological museum. These lesions were too small to be noted on radiographs, and consisted of two inconspicuous enamel lesions in a mandibular left first molar tooth (309), a clinically visible white spot area containing an enamel lesion in a mandibular left fourth premolar tooth (308), and a root surface caries in the 308 of a different specimen. Histologic examination using special stains and polarized light revealed both initial and early initial stage enamel caries, as well as root surface caries. Knoop hardness measurements confirmed these findings, considered the first documented cases of feline caries.     

Fast variability of tera-electron volt gamma rays from the radio galaxy M87

The detection of fast variations of the tera-electron volt (TeV) (10(12) eV) gamma-ray flux, on time scales of days, from the nearby radio galaxy M87 is reported. These variations are about 10 times as fast as those observed in any other wave band and imply a very compact emission region with a dimension similar to the Schwarzschild radius of the central black hole. We thus can exclude several other sites and processes of the gamma-ray production. The observations confirm that TeV gamma rays are emitted by extragalactic sources other than blazars, where jets are not relativistically beamed toward the observer.     

Genome sequence diversity and clues to the evolution of variola (smallpox) virus

Comparative genomics of 45 epidemiologically varied variola virus isolates from the past 30 years of the smallpox era indicate low sequence diversity, suggesting that there is probably little difference in the isolates' functional gene content. Phylogenetic clustering inferred three clades coincident with their geographical origin and case-fatality rate; the latter implicated putative proteins that mediate viral virulence differences. Analysis of the viral linear DNA genome suggests that its evolution involved direct descent and DNA end-region recombination events. Knowing the sequences will help understand the viral proteome and improve diagnostic test precision, therapeutics, and systems for their assessment.