Adherence of Actinobacillus pleuropneumoniae to primary cultures of porcine lung epithelial cells

To study adherence of Actinobacillus pleuropneumoniae to porcine lower respiratory epithelium, a cell culture model was developed using primary cultures of porcine lung epithelial cells (LEC). Adherence assays were performed and results were compared with data obtained with swine kidney cells (SK6). A. pleuropneumoniae efficiently adhered to LEC with up to 62 bacteria per cell after 2h of incubation. Reference strain of serotype 3 (R3) adhered better to LEC than reference strains of serotypes 1 (R1), 7 (R7) and 8 (R8). Overall the adherence to LEC was more rapid and up to 30-fold more efficient than adherence to SK6 cells. In search for the mechanism involved in the adherence event, we tested the effect of LPS which has previously been demonstrated to cause adherence of the pathogen to upper respiratory epithelium. Adherence assays with LPS transposon mutants demonstrated unaltered (mutant with modification in core/lipid A moiety) or even three-fold more adherence (mutants lacking O antigen) compared to the parent micro-organisms. Purified LPS of strains R1, R3, R7 and R8 did not inhibit adherence of R8 to LEC either, suggesting that LPS and particularly the O-antigen are not essential for adherence of A. pleuropneumoniae to LEC. The efficient, LPS-independent adherence of A. pleuropneumoniae to LEC cells indicates that A. pleuropneumoniae may carry different, cell type-specific adhesins and that primary cultures of lower respiratory epithelium are valuable infection models in studying A. pleuropneumoniae pathogenesis.     

An Aqueous Extract of the Dry Mycelium of Penicillium chrysogenum Induces Resistance in Several Crops under Controlled and Field Conditions

We have examined the effect of Pen, an aqueous extract of the dry mycelium of Penicillium chrysogenum, on plant–pathogen interactions. Pen controlled a broad range of pathogens on several crop plants under greenhouse and field conditions. Pen protected grapevine from downy and powdery mildew (caused by Plasmopara viticola and Uncinula necator), tomato from early blight (caused by Phytophthora infestans), onion from downy mildew (Peronospora destructor) and apple trees from apple scab (caused by Venturia inaequalis) to a similar extent as fungicides such as copper and sulphur or well-known inducers such as benzothiadiazole or β-aminobutyric acid. Pen had no major direct fungicidal effect and is thus supposed to protect plants by activating their defense mechanisms. The raw material for extraction of Pen was available in constant quality, a prerequisite for commercial application. Under certain conditions, Pen caused phytotoxic side effects. The symptoms mostly consisted of small necrotic spots or, more rarely, of larger necrotic areas. The development of the symptoms was dependent on several parameters, including concentration of Pen, the number of applications, the persistence on the plant tissue, the plant species and variety and environmental conditions. In grapevine, a partially purified fraction of Pen was much less toxic than the crude Pen extract, but protected the plants to a similar extent against P. viticola. Our data show that Pen has interesting and unique properties as a plant protection agent, but more research is needed to further reduce its phytotoxic side effects.     

A nonlinear, dynamic, simulation model for transport, and whole plant allocation of systemic xenobiotics following foliar application. IV: Physicochemical properties requirements for optimum absorption and translocation

The relationship between the physicochemical properties (molar volume, partition coefficient, and dissociation constant) of slow-acting systemic postemergence xenobiotics and their uptake and translocation to the sites of action was investigated using the nonlinear, dynamic simulation model ERMESSE. When the pK_a was held constant at 4.0, the model enables the prediction of the uptake of a systemic xenobiotic as a function of its partition coefficient and molar volume. The model also considered the effects of the physicochemical properties of a systemic xenobiotic on its long-distance translocation within the vascular tissues. For instance, when the log K_ow and pK_a were held constant at 1.5 and 6.0, respectively, the model predicted a higher translocation rate (55%) for molecules with a small (e.g., MV = 100 cm³ mol⁻¹) as opposed to a large (e.g., MV = 300 cm³ mol⁻¹, 33%) molar volume. In addition, the theoretical predictions from the ERMESSE model showed that any xenobiotic with a molar volume not exceeding 300 cm³ mol⁻¹ could provide an uptake ?50% and a translocation rate ?25% when its log K_ow is between −0.5 and 2.5 and its pK_a is between 0.0 and 8.0.     

Buchbesprechungen

Ohne Zusammenfassung     

Untersuchungen über die Ausbreitung von Nonnenfaltern durch Markierung mit Seltenen Erden

Zusammenfassung In der vorliegenden Arbeit werden Laborversuche zur Markierung von Nonnenraupen und Nonnenfaltern mit den Seltenen Erden Europium und Dysprosium behandelt, sowie Freilanduntersuchungen zum Studium der Ausbreitung mit Europium gekennzeichneter Nonnenfalter. Imagines, die mit Mengen von 1/Exemplar im Raupenstadium besprüht worden waren, erwiesen sich, ebenso wie im Vorjahr in derselben Weise behandelte Kiefernspinner, als deutlich markiert. Zur Kennzeichnung der Falter gelangten im Labor und im Freiland 10 Europium, im Labor auch 10 Dysprosium/Exemplar mittels Besprühung erfolgreich zur Anwendung. Die Ausbreitungsuntersuchungen ergaben einen Überflug markierter Falter auf eine Entfernung von 2 km.

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Summary The present paper describes laboratory experiments in marking nun-caterpillars and nun-moths with the rare earths Europium and Dysprosium, as well as field studies on the spread of nun-moths marked with Europium. Nun-moths, sprayed with quantities of 1/individual in the caterpillar stage, proved distinctly marked, and so did pine spinners(Dendrolimus pini) treated the same way past year. Marking of moths succeeded in both laboratory and field by spraying with 10 Europium, in the laboratory also with 10 Dysprosium per individual. Spreading studies revealed marked moths overflying distances of 2 kilometres.

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Résumé L'ouvrage présent traite d'essais en laboratoire sur le marquage de chenilles et de papillons de la Nonne(L. monacha) au moyen des terres rares Europium et Dysprosium, ainsi que de recherches au terrain sur l'expansion de papillons de cette espèce marqués d'Europium. Les images de la Nonne, ayant été aspérgées au stade larvaire d'une dose de 1 par individu, se sont avérées distinctement marquées, de même que les Bombyx du Pin traités de la même manière l'année passée. — Le marquage de papillons a été effectué avec succès au laboratoire et au terrain au moyen de 10 d'Europium — au laboratoire aussi de 10 de Dysprosium — par individu, appliqués par aspersion. Les recherches sur l'expansion ont révélé un survol de papillons marqués à une distance de 2 km.

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Für weitgehende Unterstützung der entomologischen Untersuchungen sei den Herren Dr. W. Schedl, Förster C. Holzschuh und Förster F. Stradner der forstlichen Bundesversuchsanstalt, der physikalischen Auswertung Herrn Ing. D. Koch, Reaktorzentrum Seibersdorf, herzlich gedankt. Besonderer Dank sei auch der Landesforstinspektion Niederösterreich, der Bezirksforstinspektion Waidhofen/Thaya und der Forstverwaltung von Fischen-Ankern für großzügige Hilfe bei der Durchführung der Freilanduntersuchungen ausgesprochen.     

Über die Anwendung des Begriffs „Hege“ beim Bisam

Ohne Zusammenfassung     

Beobachtungen zum Verhalten des Bisam bei temporärer Trockenlegung eines Fließgewässer

Ohne Zusammenfassung     

Site of acid-base relevant ion transfer in the gills of rainbow trout (Oncorhynchus mykiss) exposed to environmental hypercapnia

In order to delineate the contribution of primary vs. secondary circulatory circuits in the gill for acid-base and ionic regulation, the flow and composition of the fluids in the central venous sinus (CVS) and the systemic circuit of rainbow trout were studied by application of a previously developed microcannulation technique during normocapnic and hypercapnic conditions. The average haematocrit (Hct) of blood from dorsal aorta (DA) and sinus venosus (SV) ranged from 20.1 to 26.7%, whereas average Hct in the fluid from the branchial vein (BV), representing drainage from the central venous sinus (CVS), was in the range of 4.2 to 7.0%. Under normocapnic conditions, the largest fraction of cardiac output, 92.9%, was directed through the systemic vascular circuit, whereas the CVS circuit was perfused with 7.1 % of cardiac output. Hypercapnia did not significantly affect the blood flow distribution between the two circuits. The pattern of acid-base regulation in dorsal aortic blood reflected the characteristic response of fish exposed to environmental hypercapnia. Upon initiation of environmental hypercapnia (2% CO₂), plasma P_{CO 2} was elevated in all three flow compartments (CVS, DA, SV), inducing an extracellular respiratory acidosis of about 0.4 pH units. pH and [HCO₃ ^-] values in the DA were consistently lower, than those for both CVS and SV sites throughout the hypercapnic period. During the 8h of exposure plasma bicarbonate concentration was elevated by about 12 mM, complemented by a fall in extracellular [Cl^-] of about 10 mM in all three compartments. The amount of HCO₃ ^- gained at the CVS site during 8h of hypercapnia (3.3 mmol · kg^-1) exceeds the amount accumulated in the extracellular space (2.1 mmol·kg^-1), suggesting the CVS as the main site of ionic acid-base regulation in trout.     

Haloperoxidase Mediated Quorum Quenching by Nitzschia cf pellucida: Study of the Metabolization of N-Acyl Homoserine Lactones by a Benthic Diatom

Diatoms are known to produce a variety of halogenated compounds, which were recently shown to have a role in allelopathic interactions between competing species. The production of these compounds is linked to haloperoxidase activity. This research, has shown that this system may also be involved in diatom-bacteria interactions via the H₂O₂ dependent inactivation of a type of quorum sensing (QS) molecule, i.e., N-β-ketoacylated homoserine lactones (AHLs), by a natural haloperoxidase system from the benthic diatom Nitzschia cf pellucida. The AHL degradation pathway towards corresponding halogenated derivatives was elucidated via HPLC-MS analysis and the synthesis of a broad series of novel halogenated AHL analogues as reference compounds. Furthermore, their biological activity as quorum sensing modulators was directly compared and evaluated against a series of naturally occurring β-keto-AHLs. It has been demonstrated that the loss of the QS activity results from the final cleavage of the halogenated N-acyl chain of the signal molecules.