Diagnostic assays based on esterase-mediated resistance mechanisms in western corn rootworms (Coleoptera: Chrysomelidae)

Resistance to methyl-parathion among Nebraska western corn rootworm, Diabrotica virgifera virgifera LeConte, populations is associated with increased hydrolytic metabolism of an organophosphate insecticide substrate. An electrophoretic method to identify resistant individuals based on the staining intensity of esterase isozymes on nondenaturing polyacrylamide gels was developed. Three groups of esterases (I, II, and III) were visible on the gels, but only group II esterase isozymes were intensified in resistant populations. A total of 26 and 31 field populations of western corn rootworms from Nebraska (in 1998 and 1999, respectively) were assessed with nondenaturing polyacrylamide gel electrophoresis (PAGE) assays and diagnostic concentration bioassays. Significant correlations were observed between the two diagnostic assays. Group II esterase isozymes provide a reliable biochemical marker for detection of methyl-parathion resistance in individual western corn rootworms and a tool for monitoring the frequency of resistant individuals in field populations.     

Zebrafish ProVEGF-C Expression,Proteolytic Processing and Inhibitory Effect of Unprocessed ProVEGF-C during Fin Regeneration

Background

In zebrafish, vascular endothelial growth factor-C precursor (proVEGF-C) processing occurs within the dibasic motif HSIIRR₂₁₄ suggesting the involvement of one or more basic amino acid-specific proprotein convertases (PCs) in this process. In the present study, we examined zebrafish proVEGF-C expression and processing and the effect of unprocessed proVEGF-C on caudal fin regeneration.

Methodology/Principal Findings

Cell transfection assays revealed that the cleavage of proVEGF-C, mainly mediated by the proprotein convertases Furin and PC5 and to a less degree by PACE4 and PC7, is abolished by PCs inhibitors or by mutation of its cleavage site (HSIIRR₂₁₄ into HSIISS₂₁₄). In vitro, unprocessed proVEGF-C failed to activate its signaling proteins Akt and ERK and to induce cell proliferation. In vivo, following caudal fin amputation, the induction of VEGF-C, Furin and PC5 expression occurs as early as 2 days post-amputation (dpa) with a maximum levels at 4–7 dpa. Using immunofluorescence staining we localized high expression of VEGF-C and the convertases Furin and PC5 surrounding the apical growth zone of the regenerating fin. While expression of wild-type proVEGF-C in this area had no effect, unprocessed proVEGF-C inhibited fin regeneration.

Conclusions/Significances

Taken together, these data indicate that zebrafish fin regeneration is associated with up-regulation of VEGF-C and the convertases Furin and PC5 and highlight the inhibitory effect of unprocessed proVEGF-C on fin regeneration.     

Molecular composition of the outer membrane of Escherichia coli and the importance of protein-lipopolysaccharide interactions

Whole cells of Escherichia coli strains 0111, K12 and B as well as the ampicillin-resistant mutant K12 D21 and several lipopolysaccharide (LPS) mutants derived from this strain were analyzed for their molar LPS content per mg dry weight. An increase of the LPS concentration in some LPS mutants was substantiated by analyzing isolated cell walls and relating the molar LPS content to the murein subunit as measure of cell surface area. The increase of LPS was paralleled by increasing amounts of phospholipid while the overall protein content in the outer membrane decreased.According to the pattern of major outer membrane proteins in the various strains and the respective LPS structures, protein-LPS interactions are discussed as important requirements for outer membrane assembly and stability.Abbreviations LPS lipopolysaccharide - SDS sodium dodecyl-sulfate Dedicated to Dr. Otto Lüderitz on the occasion of his 60th birthday     

Respiration, cyanide-insensitive oxygen uptake and oxidative phosphorylation in cyanobacteria

Cyanide-insensitive oxygen uptake in the dark of 9 species of cyanobacteria was 6–20% of the total oxygen uptake of intact cells. In Phormidium , no cyanideinsensitive oxygen uptake was observed. In intact cells, the I₅₀ value for cyanide was significantly lower in cyanobacteria of the taxonomic sections I to III (1–9 μ M ) than in those from section IV and V (10–60 μ M ). Cyanide-insensitive oxygen uptake in the cell-free system of Anabaena variabilis was not affected by typical inhibitors of the alternative pathway of plants. Cell-free oxidation of cytochrome c was completely inhibited by cyanide with an I₅₀ value of 0.5–1 μ M . Electron transport of intact cells without cyanide present yielded P/O ratios of 0.7–3.0. The data on oxidative phosphorylation using intact cells and the cell-free system, indicate that cyanide-insensitive oxygen uptake is not coupled to ATP formation.     

Der Handflügelindex südwestpalaearktischer Raubwürger (Lanius excubitor) — Kritik eines Klischees

Zusammenfassung Der klassische Fall von Zuganpassung im Flügelbau der europäischen Würger (Lanius minor, L. excubitor) ist Anlaß zu einer kritischen Betrachtung. Diese erfolgt durch Vergleich der Proportionsunterschiede südwestpalaearktischerL. excubitor (und asiatischerL. excubitor/L. sphenocercus), die trotz erheblicher Divergenzen keine Zuganpassungen sein können. Sie sind allometrisch (L. e. koenigi) oder im Zuge evolutionärer Trends durch effektive Umkonstruktion bedingt. Der Fall zeigt, daß die Zusammenführung vergleichender Untersuchungen in Systematik, Zoogeographie, Morphologie und Ökologie verstärkt zu werden verdient.

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The wing tip index of southwest Palaearctic Great Grey Shrikes (Lanius excubitor) — a hackneyed phrase re-analyzed

Summary The classical case of migrational adaptation in wing construction of European Grey Shrikes (Lanius minor, L. excubitor) is re-investigated critically. The study is based on the comparison of proportional differences of SW PalaearcticL. excubitor and AsianL. excubitor/L. sphenocercus wings. Despite considerable differences these cannot considered as migrational adaptations. They are allometric (L. e. koenigi) or they are caused by constructive differentiation within evolutionary trends. As shown in this example, comparative investigations in systematics, zoo-geography, morphology, and ecology need to be enhanced and the results to be viewed multidisciplinary.

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Dem Andenken an Dr. H. E. Wolters gewidmet     

Cystic fibrosis—a single locus disease?

Summary In a population genetics study of cystic fibrosis (CF), we investigated the state of health of 1276 first cousins of CF index patients. Six hundred seventy-five married aunts and uncles (siblings of CF index patients' mothers and fathers) who had at least one child were interviewed. In only 1 of these 675 families, three children of a total of eight had died of CF. If CF occurs more frequently than in 1 in 3000 newborn babies in our population, our investigation supports the hypothesis that CF is caused by mutations at more than one locus. We also determined that the evidence furnished by such a study of other, more uncommon autosomal recessive disorders is limited.     

Interactions between Plants and Epiphytic Bacteria Regarding Their Auxin Metabolism

Homogenates of epicotyls or roots of nonsterile pea plants incubated with tryptophan produce IAA within 1 to 4 hours, which was detected by means of the Avena curvature test and thin layer chromatography. Three results prove this short-term IAA production to be mainly caused by epiphytic bacteria: 1) Homogenates of sterile plant parts catalyze a conversion of tryptophan to IAA, a hundredfold lower. 2) Chloramphenicol or streptomycin very actively reduce the IAA gain obtained with nonsterile homogenates. 3) Washing solutions of nonsterile plant parts which do not contain plant enzymes but only epiphytic bacteria, produce IAA from tryptophan, too. IAA synthesis from tryptophan in vitro by enzymes of the pea plant occurs with lower intensity than hitherto known; possibly it is physiologically unimportant. It is discussed to what extent the hitherto existing research work about the IAA biogenesis in higher plants might be incriminated by disregarding tbe rôle of epiphytic bacteria.     

Skeletteile des pleistozänen Moschusochsen aus Westfalen

An Atlas and a Metacarpale ofOvibos moschatus (Zimmermann) are described from deposits of the Weichselian at the Lippe river in Westphalia. A difference to a recent Atlas ofOvibos cannot be recognized. Relations between bone structure and mode of life are pointed out.     

Interactions between Plants and Epiphytic Bacteria Regarding Their Auxin Metaholism

During an ether extraction (20 h, 4°C), nonsterilc pea epicotyls deliver at least 5 times more auxin than sterile ones. A great part of the additional auxin originates from a bacterial auxin production during the extraction. Presence of chloramphenicol or streptomycin during the extraction lowers the auxin amount extractable from nonsterile epicotyls. In extraction conditions (i.e. covered with ether, 20 h, 4°C), epiphytic bacteria contained in homogenates of nonsterile plant parts produce IAA from added tryptophan. Furthermore, first results are presented underlining the fact that epiphytic bacteria already produce auxin at the surface of nonsterile plant parts (before an extraction).