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721.
Adam Miszta Radek Machán Ales Benda Andre J Ouellette Wim Th Hermens Martin Hof 《Journal of peptide science》2008,14(4):503-509
The present study has two main objectives. The first is to characterize antimicrobial peptide (AMP) cryptdin-4 (Crp-4) interactions with biological membranes and to compare those interactions with those of magainin 2. The second is to combine the complementary experimental approaches of laser scanning microscopy (LSM), ellipsometry, and Z-scan fluorescence correlation spectroscopy (FCS) to acquire comprehensive information on mechanisms of AMP interactions with supported phospholipid bilayers (SPBs)-a popular model of biological membranes. LSM shows appearance of inhomogeneities in spatial distribution of lipids in the bilayer after treatment with Crp-4. Ellipsometric measurements show that binding of Crp-4 does not significantly change the lipid structure of the bilayer (increase in adsorbed mass without a change in thickness of adsorbed layer). Furthermore, Crp-4 slows the lateral diffusion of lipids within the membrane as shown by Z-scan FCS. All changes of the bilayer induced by Crp-4 can be partially reversed by flushing the sample with excess of buffer. Bilayer interactions of magainin 2 are significantly different, causing large loss of lipids and extensive damage to the bilayer. It seems likely that differences in peptide mode of action, readily distinguished using these combined experimental methods, are related to the distinctive beta-sheet and alpha-helical structures of the respective peptides. 相似文献
722.
723.
724.
Zusammenfassung Nachdem sich gezeigt hatte, daB nach generationenlanger Beeinflussung mit Follikelhormon und zusatzlicher R?ntgenbestrahlung
auch der Prozentsatz der sichtbaren Mutationen stark gesteigert wird (Dotterweich 1941), wurde die Frage nach der Qualit?t der in dieser Weise erhaltenen Mutationen geprüft.
Die Beeinflussung wurde mit Progynon (20 M.-E. pro ccm N?hrboden) fünf Generationen lang durchgeführt. Die M?nnchen der fünften
beeinflu?ten Generation wurden, ebenso wie diejenigen der unbehandelten Kontrollkultur einer R?ntgenbestrahlung von 4000 r
ausgesetzt und im Anschlu? daran mit
-Weibchen gepaart.
Der Vergleich der entsprechenden Mutationstypen bei beeinflu?ten und unbeeinflu?ten Kulturen zeigte eine auff?llig starke
Zunahme der Borsten- und der Flugeladermutationen bei den mit Progynon beeinflu?ten Fliegen.
Eine Kultur, die 58 Generationen auf einem N?hrboden mit gleicher Progynonmenge gelebt hatte, zeigte hinsichtlich des bevorzugten
Auftretens dieser beiden Mutationstypen ein sehr ?hnliches Bild.
Aus den Resultaten ist zu schlieBen, da? unterschwellige chemische bzw. physiologische Reize, die allein nicht imstande sind,
Mutationen auszul?sen, spezifische Wirkungen auf die Gene ausüben k?nnen.
Die wichtigsten der aufgetretenen Mutationen werden — ebenso wie die Abdomenvariationen — beschrieben.
Mit 3 Textfiguren und 2 Tabellen 相似文献
725.
Liselotte Ronsdorf 《Planta》1931,14(2):482-514
Ohne ZusammenfassungMit 10 Textabbildungen. 相似文献
726.
Ohne Zusammenfassung 相似文献
727.
Peter Staib Marianne Kretschmar Thomas Nichterlein Gerwald Köhler Sonja Michel Herbert Hof Jörg Hacker & Joachim Morschhäuser 《Molecular microbiology》1999,32(3):533-546
An understanding of the complex interactions between pathogenic microbes and their host must include the identification of gene expression patterns during infection. To detect the activation of virulence genes in the opportunistic fungal pathogen Candida albicans in vivo by host signals, we devised a reporter system that is based on FLP-mediated genetic recombination. The FLP gene, encoding the site-specific recombinase FLP, was genetically modified for expression in C. albicans and fused to the promoter of the SAP2 gene that codes for one of the secreted aspartic proteinases, which are putative virulence factors of C. albicans. The SAP2P-FLP fusion was integrated into one of the SAP2 alleles in a strain that contained a deletable marker that conferred resistance to mycophenolic acid and was flanked by direct repeats of the FLP recognition target (FRT). Using this reporter system, a transient gene induction could be monitored at the level of single cells by the mycophenolic acid-sensitive phenotype of the colonies generated from such cells after FLP-mediated marker excision. In two mouse models of disseminated candidiasis, SAP2 expression was not observed in the initial phase of infection, but the SAP2 gene was strongly induced after dissemination into deep organs. In contrast, in a mouse model of oesophageal candidiasis in which dissemination into internal organs did not occur, no SAP2 expression was detected at any time. Our results support a role of the SAP2 gene in the late stages of an infection, after fungal spread into deep tissue. This new in vivo expression technology (IVET) for a human fungal pathogen allows the detection of virulence gene induction at different stages of an infection, and therefore provides clues about the role of these genes in the disease process. 相似文献
728.
Sven Rubanschi Sebastian T. Meyer Christian Hof Wolfgang W. Weisser 《Diversity & distributions》2023,29(4):492-508
Aim
Environmental conditions define the suitability of an area for biotopes, and any area can be suitable for several biotopes. However, most previous studies modelled the distribution of single biotopes ignoring the potential co-occurrence of biotopes in one area, which limits the usefulness of such models for conservation and restoration planning. In this study, we described the potential biotope composition of an area in response to environmental conditions.Location
Bavaria, Federal State of Germany.Methods
Based on the Bavarian biotope mapping data, we modelled the distribution of 29 terrestrial biotopes based on six climate variables and six chemical and four physical soil properties using the species distribution modelling algorithm Maxent.Results
For most biotopes, we found that climate variables were more important than soil variables for the biotope distribution and that the area of the predicted biotope distribution was larger than the observed distribution. The potential biotope composition illustrated that while 8% of the area in Bavaria was not sufficiently suitable for any analysed biotope, 92% of the modelled area in Bavaria was suitable for at least one biotope, 84% for two and 77% for at least three biotopes. The difference in suitability between the most suitable biotopes in composition was minor. Further, over one-quarter of the modelled area was suitable for 6–8 different biotopes.Main Conclusions
Our study showed that considering a composition of potentially suitable biotopes in a raster cell, instead of only the most suitable biotope, provides valuable information to identify conservation priorities and restoration opportunities. 相似文献729.
730.
Measurements of relative DNA per nucleus of cells from various tissues show that cell differentiation can occur in the absence of polyploidy in higher plants. In Pisum polyploidy was present in roots, sepals, pods, pistils, and stamens but not in petals or leaves. In Triticum cells of leaves exhibited some polyploidy, but no polyploid cells were present in mature roots. No polyploid cells were found in any tissue of Helianthus examined (roots, cotyledons, stems, leaves, sepals, petals, pistils, and stamens). Therefore, as a general rule, polyploidy should not be considered essential in tissue or organ differentiation of higher plants. In Helianthus polyploidy is unnecessary for the completion of the life cycle. 相似文献