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951.
Gerhard Tutz 《Biometrical journal. Biometrische Zeitschrift》1991,33(5):519-527
Direct kernels, due to LAUDER (1983), as an alternative to the indirect kernel method in discriminant analysis are considered. It is shown that direct kernels may be based on any kernel function known in discrete density estimation. The choice of smoothing parameters is based on general loss functions and a family of loss functions which are specific for the discrimination problem is introduced. Examples with distance dependent and distance independent smoothing parameters are given to illustrate the applicability. 相似文献
952.
953.
U K Vogt 《Journal of experimental botany》2001,52(360):1527-1536
Differences in the seasonal variation in stem water potential between the two shrub species Sorbus aucuparia and Sambucus nigra were related with their vulnerability to xylem cavitation. It was also demonstrated indirectly that the two species differ in the extent to which they reverse cavitation. Seasonal variation in stem water potential was investigated during three growing seasons with in situ stem psychrometers. Sorbus experienced wide water potential variations and reached a minimum of -4.2 MPa during drought. Under the same microclimatic conditions, Sambucus experienced consistent stem water potentials with a minimum of -1.7 MPa. The relationship between percentage loss in hydraulic conductivity (PLC) and water potential (hydraulic vulnerability curve) of the two species differed in shape: a flat curve with nearly total loss of conductivity at -6 MPa was found for SORBUS: Sambucus showed a steep vulnerability curve with 90% loss conductivity at -2.2 MPa. Thus, Sambucus is extremely vulnerable to cavitation, but Sorbus is an almost invulnerable species. This different cavitation resistance adjusted the ranges of field stem water potential that the species experienced. Finally, seasonal courses of naturally occurring (native) embolism were compared with calculated PLC courses. This comparison indicates that Sorbus did not refill embolized xylem vessels whereas Sambucus reversed embolism. It was concluded that species which are highly vulnerable to cavitation and drought-induced embolism need refilling of embolized vessels as well as isohydric water potential patterns as two strategies of survival. 相似文献
954.
Cloning of the genes encoding urease from Proteus vulgaris and sequencing of the structural genes 总被引:16,自引:0,他引:16
A fragment of chromosomal DNA from proteus vulgaris encoding urease was cloned and expressed in Escherichia coli. A 3 kbp region was sequenced and revealed three open reading frames with homology to jack bean (Canavalia ensiformis) urease. The smallest protein (11 kDa) was homologous to the N-terminus of the plant enzyme and the largest polypeptide (61 kDa) corresponded to the C-terminus. The large protein contained conserved regions and a cysteine residue which is known to be catalytically important in the plant enzyme. A protein of 12 kDa showed homology to residues 132 to 237 of jack bean urease. 相似文献
955.
Rye bread and synthetic bread odorants – effective trap bait and lure for German cockroaches
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Bread‐in‐beer and bread‐in‐water are prevalent home recipe trap baits for attracting German cockroaches (GCRs), Blattella germanica (L.) (Dictyoptera: Blattellidae), which are significant urban pests. Our objectives were to (1) test the attractiveness of these baits, (2) study the underlying factors of GCR attraction, and (3) determine whether a blend of synthetic bread odorants could replace bread in a trap lure. In large‐arena laboratory experiments with laboratory‐reared GCR males, traps baited with rye bread not only captured eightfold more males than unbaited control traps but also most males released into bioassay arenas. Neither beer nor water enhanced the attractiveness of bread. Bread crust as a bait was more effective than bread crumbs. As Porapak Q headspace volatile extracts of rye bread attracted GCRs, all rye bread odorants in extracts were identified by gas chromatography‐mass spectrometry. Synthetic rye bread odorants and other known bread odorants were then assembled into a master blend. This master blend, and even partial blends lacking certain groups of organic volatiles such as aldehydes and ketones, proved very attractive to GCRs. We conclude that rye bread could be used as an effective bait in retainer traps or, laced with insecticide, as a food source in bait stations. A lure of synthetic bread odorants may eventually replace bread as bait, but the minimum number of essential odorants for that lure has yet to be determined. 相似文献
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957.
Suzanne T. E. Lommen Caspar A. Hallmann Eelke Jongejans Bruno Chauvel Melinda Leitsch-Vitalos Alla Aleksanyan Peter Tóth Cristina Preda Maja Šćepanović Huseyin Onen Barbara Tokarska-Guzik Paulina Anastasiu Zita Dorner Annamária Fenesi Gerhard Karrer Katalin Nagy Gyula Pinke Viktor Tiborcz Gergely Zagyvai Mihály Zalai Gabriella Kazinczi Robert Leskovšek Danijela Stešević Guillaume Fried Levani Kalatozishvili Andreas Lemke Heinz Müller-Schärer 《Biological invasions》2018,20(6):1475-1491
To better manage invasive populations, it is vital to understand the environmental drivers underlying spatial variation in demographic performance of invasive individuals and populations. The invasive common ragweed, Ambrosia artemisiifolia, has severe adverse effects on agriculture and human health, due to its vast production of seeds and allergenic pollen. Here, we identify the scale and nature of environmental factors driving individual performance of A. artemisiifolia, and assess their relative importance. We studied 39 populations across the European continent, covering different climatic and habitat conditions. We found that plant size is the most important determinant in variation of per-capita seed and pollen production. Using plant volume as a measure of individual performance, we found that the local environment (i.e. the site) is far more influential for plant volume (explaining 25% of all spatial variation) than geographic position (regional level; 8%) or the neighbouring vegetation (at the plot level; 4%). An overall model including environmental factors at all scales performed better (27%), including the weather (bigger plants in warm and wet conditions), soil type (smaller plants on soils with more sand), and highlighting the negative effects of altitude, neighbouring vegetation and bare soil. Pollen and seed densities varied more than 200-fold between sites, with highest estimates in Croatia, Romania and Hungary. Pollen densities were highest on arable fields, while highest seed densities were found along infrastructure, both significantly higher than on ruderal sites. We discuss implications of these findings for the spatial scale of management interventions against A. artemisiifolia. 相似文献
958.
Cédric M. Vogt Monika Hilbe Mathias Ackermann Claudio Aguilar Catherine Eichwald 《Microbial cell factories》2018,17(1):187
Background
We previously engineered Bacillus subtilis to express an antigen of interest fused to TasA in a biofilm. B. subtilis has several properties such as sporulation, biofilm formation and probiotic ability that were used for the oral application of recombinant spores harboring Echinococcus granulosus paramyosin and tropomyosin immunogenic peptides that resulted in the elicitation of a specific humoral immune response in a dog model.Results
In order to advance our understanding of the research in oral immunization practices using recombinant B. subtilis spores, we describe here an affordable animal model. In this study, we show clear evidence indicating that a niche is required for B. subtilis recombinant spores to colonize the densely populated mice intestinal microbiota. The reduction of intestinal microbiota with an antibiotic treatment resulted in a positive elicitation of local humoral immune response in BALB/c mice after oral application of recombinant B. subtilis spores harboring TasA fused to E. granulosus (102-207) EgTrp immunogenic peptide. Our results were supported by a lasting prevalence of spores in mice feces up to 50 days after immunization and by the presence of specific secretory IgA, isolated from feces, against E. granulosus tropomyosin.Conclusions
The reduction of mouse intestinal microbiota allowed the elicitation of a local humoral immune response in mice after oral application with spores of B. subtilis harboring immunogenic peptides against E. granulosus.959.
960.
Jason L. Wedding Barry Lai Stefan Vogt Hugh H. Harris 《Biochimica et Biophysica Acta (BBA)/General Subjects》2018,1862(11):2393-2404