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101.
Thomas Weisse Michael Moser Ulrike Scheffel Peter Stadler Thomas Berendonk Guntram Weithoff Helmut Berger 《European journal of protistology》2013,49(2):255-271
We investigated the morphology, phylogeny of the 18S rDNA, and pH response of Oxytricha acidotolerans sp. nov. and Urosomoida sp. (Ciliophora, Hypotricha) isolated from two chemically similar acid mining lakes (pH ~ 2.6) located at Langau, Austria, and in Lusatia, Germany. Oxytricha acidotolerans sp. nov. from Langau has 18 frontal-ventral-transverse cirri but a very indistinct kinety 3 fragmentation so that the assignment to Oxytricha is uncertain. The somewhat smaller species from Lusatia has a highly variable cirral pattern and the dorsal kineties arranged in the Urosomoida pattern and is, therefore, preliminary designated as Urosomoida sp. The pH response was measured as ciliate growth rates in laboratory experiments at pH ranging from 2.5 to 7.0. Our hypothesis was that the shape of the pH reaction norm would not differ between these closely related (3% difference in their SSU rDNA) species. Results revealed a broad pH niche for O. acidotolerans, with growth rates peaking at moderately acidic conditions (pH 5.2). Cyst formation was positively and linearly related to pH. Urosomoida sp. was more sensitive to pH and did not survive at circumneutral pH. Accordingly, we reject our hypothesis that similar habitats would harbour ciliate species with virtually identical pH reaction norm. 相似文献
102.
Robert Gliniars Gabriel Sebastian Becker Désirée Braun Helmut Dalitz 《Trees - Structure and Function》2013,27(4):1129-1138
Monthly stem increment of 766 trees was assessed for 7 years in Kakamega Forest, Kenya and related to monthly climatic variables. Mean stem increment of all tree individuals correlated negatively with maximum temperature but not with mean and minimum temperatures. For the precipitation variables sum of precipitation and number of rainy days we found positive correlations. Stem increment of the trees in the early-, mid-, and late-successional groups correlated positively with the number of rainy days. For late-successional trees increment correlated negatively with mean and maximum temperature and positively with all other precipitation variables. For mid-successional trees we found a negative correlation with mean temperature. In addition, the stem increment of most species related positively to precipitation variables and negatively to mean and maximum temperature. In view of the expected increasing temperatures and fewer but heavier rain events, our results suggest that climate change will lead to a reduction in stem increment. The results appertaining to the successional groups imply that early and mid-successional species are better equipped to perform well under the expected future climatic conditions than the late-successional species. This could reduce the role of this East African forest as a carbon store. As the responses to climatic variables were highly group- and species-specific it is likely that climate change will result in a species composition shift, presumably in favour of drought-resistant and heat-tolerating species. 相似文献
103.
Soumitra Paul Chowdhury Kristin Dietel Manuela R?ndler Michael Schmid Helmut Junge Rainer Borriss Anton Hartmann Rita Grosch 《PloS one》2013,8(7)
The soil-borne pathogen Rhizoctonia solani is responsible for crop losses on a wide range of important crops worldwide. The lack of effective control strategies and the increasing demand for organically grown food has stimulated research on biological control. The aim of the present study was to evaluate the rhizosphere competence of the commercially available inoculant Bacillus amyloliquefaciens FZB42 on lettuce growth and health together with its impact on the indigenous rhizosphere bacterial community in field and pot experiments. Results of both experiments demonstrated that FZB42 is able to effectively colonize the rhizosphere (7.45 to 6.61 Log 10 CFU g−1 root dry mass) within the growth period of lettuce in the field. The disease severity (DS) of bottom rot on lettuce was significantly reduced from severe symptoms with DS category 5 to slight symptom expression with DS category 3 on average through treatment of young plants with FZB42 before and after planting. The 16S rRNA gene based fingerprinting method terminal restriction fragment length polymorphism (T-RFLP) showed that the treatment with FZB42 did not have a major impact on the indigenous rhizosphere bacterial community. However, the bacterial community showed a clear temporal shift. The results also indicated that the pathogen R. solani AG1-IB affects the rhizosphere microbial community after inoculation. Thus, we revealed that the inoculant FZB42 could establish itself successfully in the rhizosphere without showing any durable effect on the rhizosphere bacterial community. 相似文献
104.
Helmut D. Hummler Katharina Banke Marla R. Wolfson Giuseppe Buonocore Michael Ebsen Wolfgang Bernhard Dimitrios Tsikas Hans Fuchs 《PloS one》2016,11(2)
Background
Permissive hypercapnia has been shown to reduce lung injury in subjects with surfactant deficiency. Experimental studies suggest that hypercapnic acidosis by itself rather than decreased tidal volume may be a key protective factor.Objectives
To study the differential effects of a lung protective ventilatory strategy or hypercapnic acidosis on gas exchange, hemodynamics and lung injury in an animal model of surfactant deficiency.Methods
30 anesthetized, surfactant-depleted rabbits were mechanically ventilated (FiO2 = 0.8, PEEP = 7cmH2O) and randomized into three groups: Normoventilation-Normocapnia (NN)-group: tidal volume (Vt) = 7.5 ml/kg, target PaCO2 = 40 mmHg; Normoventilation-Hypercapnia (NH)-group: Vt = 7.5 ml/kg, target PaCO2 = 80 mmHg by increasing FiCO2; and a Hypoventilation-Hypercapnia (HH)-group: Vt = 4.5 ml/kg, target PaCO2 = 80 mmHg. Plasma lactate and interleukin (IL)-8 were measured every 2 h. Animals were sacrificed after 6 h to perform bronchoalveolar lavage (BAL), to measure lung wet-to-dry weight, lung tissue IL-8, and to obtain lung histology.Results
PaO2 was significantly higher in the HH-group compared to the NN-group (p<0.05), with values of the NH-group between the HH- and NN-groups. Other markers of lung injury (wet-dry-weight, BAL-Protein, histology-score, plasma-IL-8 and lung tissue IL-8) resulted in significantly lower values for the HH-group compared to the NN-group and trends for the NH-group towards lower values compared to the NN-group. Lactate was significantly lower in both hypercapnia groups compared to the NN-group.Conclusion
Whereas hypercapnic acidosis may have some beneficial effects, a significant effect on lung injury and systemic inflammatory response is dependent upon a lower tidal volume rather than resultant arterial CO2 tensions and pH alone. 相似文献105.
106.
107.
A genetic screen for modifiers of the delta1-dependent notch signaling function in the mouse 下载免费PDF全文
Rubio-Aliaga I Soewarto D Wagner S Klaften M Fuchs H Kalaydjiev S Busch DH Klempt M Rathkolb B Wolf E Abe K Zeiser S Przemeck GK Beckers J de Angelis MH 《Genetics》2007,175(3):1451-1463
The Notch signaling pathway is an evolutionarily conserved transduction pathway involved in embryonic patterning and regulation of cell fates during development. Recent studies have demonstrated that this pathway is integral to a complex system of interactions, which are also involved in distinct human diseases. Delta1 is one of the known ligands of the Notch receptors. Mice homozygous for a loss-of-function allele of the Delta1 gene Dll1(lacZ/lacZ) die during embryonic development. Here, we present the results of two phenotype-driven modifier screens. Heterozygous Dll1(lacZ) knockout animals were crossed with ENU-mutagenized mice and screened for dysmorphological, clinical chemical, and immunological variants that are dependent on the Delta1 loss-of-function allele. First, we show that mutagenized heterozygous Dll1(lacZ) offspring have reduced body weight and altered specific clinical chemical parameters, including changes in metabolites and electrolytes relevant for kidney function. In our mutagenesis screen we have successfully generated 35 new mutant lines. Of major interest are 7 mutant lines that exhibit a Dll1(lacZ/+)-dependent phenotype. These mutant mouse lines provide excellent in vivo tools for studying the role of Notch signaling in kidney and liver function, cholesterol and iron metabolism, cell-fate decisions, and during maturation of T cells in the immune system. 相似文献
108.
109.
Spiller S Dreher S Meng G Grabiec A Thomas W Hartung T Pfeffer K Hochrein H Brade H Bessler W Wagner H Kirschning CJ 《The Journal of biological chemistry》2007,282(18):13190-13198
Evidence for specific and direct bacterial product recognition through toll-like receptors (TLRs) has been emphasized recently. We analyzed lipopeptide analogues and enterobacterial lipopolysaccharide (eLPS) for their potential to activate cells through TLR2 and TLR4. Whereas bacterial protein palmitoylated at its N-terminal cysteine and N-terminal peptides derived thereof are known to induce TLR2-mediated cell activation, a synthetic acylhexapeptide mimicking a bacterial lipoprotein subpopulation for which N-terminal trimyristoylation is characteristic (Myr(3)CSK(4)) activated cells not only through TLR2 but also through TLR4. Conversely, highly purified eLPS triggered cell activation through overexpressed TLR2 in the absence of TLR4 expression if CD14 was coexpressed. Accordingly, TLR2(-/-) macrophages prepared upon gene targeting responded to Myr(3)CSK(4) challenge, whereas TLR2(-/-)/TLR4(d/d) cells were unresponsive. Through interferon-gamma (IFNgamma) priming, macrophages lacking expression of functional TLR4 and/or MD-2 acquired sensitivity to eLPS, whereas TLR2/TLR4 double deficient cells did not. Not only TLR2(-/-) mice but also TLR4(-/-) mice were resistant to Myr(3)CSK(4) challenge-induced fatal shock. d-Galactosamine-sensitized mice expressing defective TLR4 or lacking TLR4 expression acquired susceptibility to eLPS-driven toxemia upon IFNgamma priming, whereas double deficient mice did not. Immunization toward ovalbumin using Myr(3)CSK(4) as adjuvant was ineffective in TLR2(-/-)/TLR4(-/-) mice yet effective in wild-type, TLR2(-/-), or TLR4(-/-) mice as shown by analysis of ovalbumin-specific serum Ig concentration. A compound such as Myr(3)CSK(4) whose stimulatory activity is mediated by both TLR2 and TLR4 might constitute a preferable adjuvant. On the other hand, simultaneous blockage of both of the two TLRs might effectively inhibit infection-induced pathology. 相似文献
110.
Hinney A Nguyen TT Scherag A Friedel S Brönner G Müller TD Grallert H Illig T Wichmann HE Rief W Schäfer H Hebebrand J 《PloS one》2007,2(12):e1361