No shift to a deeper water uptake depth in response to summer drought of two lowland and sub-alpine C3-grasslands in Switzerland

Temperate C3-grasslands are of high agricultural and ecological importance in Central Europe. Plant growth and consequently grassland yields depend strongly on water supply during the growing season, which is projected to change in the future. We therefore investigated the effect of summer drought on the water uptake of an intensively managed lowland and an extensively managed sub-alpine grassland in Switzerland. Summer drought was simulated by using transparent shelters. Standing above- and belowground biomass was sampled during three growing seasons. Soil and plant xylem waters were analyzed for oxygen (and hydrogen) stable isotope ratios, and the depths of plant water uptake were estimated by two different approaches: (1) linear interpolation method and (2) Bayesian calibrated mixing model. Relative to the control, aboveground biomass was reduced under drought conditions. In contrast to our expectations, lowland grassland plants subjected to summer drought were more likely (43–68 %) to rely on water in the topsoil (0–10 cm), whereas control plants relied less on the topsoil (4–37 %) and shifted to deeper soil layers (20–35 cm) during the drought period (29–48 %). Sub-alpine grassland plants did not differ significantly in uptake depth between drought and control plots during the drought period. Both approaches yielded similar results and showed that the drought treatment in the two grasslands did not induce a shift to deeper uptake depths, but rather continued or shifted water uptake to even more shallower soil depths. These findings illustrate the importance of shallow soil depths for plant performance under drought conditions.

Was hat Max Weber mit Kātib Čelebi zu tun? Ein Annäherungsversuch an Gottfried Hagen

This article responds to Gottfried Hagen’s extensive review (see Der Islam 2/2013) of my book Islamische Verantwortungsethik im 17. Jahrhundert. Ein weberianisches Verständnis der Handlungsvorstellungen Kātib Čelebis (1609– 1657). Whilst I benefitted greatly from some of Hagen’s critical remarks and his- torical elucidations, his review not only misstates crucial passages of my book but also largely disregards its main objective, which is to develop a systematic model for understanding Kātib Čelebi’s ethical stance. Besides reiterating cru- cial arguments ignored and rectifying central aspects misrepresented in Hagen’s review, I here ask how the more fundamental misunderstandings – exceeding differences in theoretical positions or empirical observations – between the au- thor’s intentions and the reviewer’s reception may be explained. Gottfried Hagen’s historiographical perspective on Kātib Čelebi diverges from my sociological take on the same subject matter to the extent that both perspectives are struggling to enter into dialogue. Such dialogue, however, remains highly desirable so as to complement a historical reconstruction of Kātib Čelebi’s life and times with a systematic, theoretically grounded understanding of his views.

Multiple roles of complement MASP-1 at the interface of innate immune response and coagulation

MASP-1 is a versatile serine protease that cleaves a number of substrates in human blood. In recent years it became evident that besides playing a crucial role in complement activation MASP-1 also triggers other cascade systems and even cells to mount a more powerful innate immune response. In this review we summarize the latest discoveries about the diverse functions of this multi-faceted protease. Recent studies revealed that among MBL-associated serine proteases, MASP-1 is the one responsible for triggering the lectin pathway via its ability to rapidly autoactivate then cleave MASP-2, and possibly MASP-3. The crystal structure of MASP-1 explains its more relaxed substrate specificity compared to the related complement enzymes. Due to the relaxed specificity, MASP-1 interacts with the coagulation cascade and the kinin generating system, and it can also activate endothelial cells eliciting pro-inflammatory signaling.

Interferon-free treatment of chronic hepatitis C with faldaprevir, deleobuvir and ribavirin: SOUND-C3, a Phase 2b study.

BACKGROUND & AIMS The safety and efficacy of the interferon-free combination of faldaprevir (NS3/A4 protease inhibitor), deleobuvir (BI 207127, non-nucleoside polymerase inhibitor), and ribavirin in treatment-naïve patients chronically infected with HCV genotype-1 was explored. METHODS SOUND-C3 was a multicenter, open-label Phase 2b study. Treatment-naïve patients chronically infected with HCV genotype-1a (IL28B CC genotype only; n = 12) and genotype-1b (n = 20) were assigned to 16 weeks of treatment with faldaprevir 120 mg once daily, deleobuvir 600 mg twice daily, and weight-based ribavirin. Patients with compensated liver disease, including cirrhosis, were eligible for inclusion in this study. The primary endpoint was sustained virological response 12 weeks after completion of therapy. RESULTS Sustained virological response rates 12 weeks after completion of therapy were 17% and 95% in patients infected with HCV genotype-1a and genotype-1b respectively. All four patients with cirrhosis achieved sustained virological response 12 weeks after completion of therapy. The most frequently reported adverse events of at least moderate intensity were anaemia (16%), nausea, vomiting and fatigue (9% each). Three (9%) patients discontinued because of adverse events. CONCLUSIONS The interferon-free regimen of faldaprevir, deleobuvir and ribavirin was efficacious in patients infected with genotype-1b and generally well tolerated.

MASP-1 of the complement system promotes clotting via prothrombin activation.

Mannan-binding lectin-associated serine protease-1 (MASP-1), a protein of the complement lectin pathway, resembles thrombin in terms of structural features and substrate specificity, and it has been shown to activate coagulation factors. Here we studied the effects of MASP-1 on clot formation in whole blood (WB) and platelet-poor plasma (PPP) by thrombelastography and further elucidated the underlying mechanism. Cleavage of prothrombin by MASP-1 was investigated by SDS-PAGE and N-terminal sequencing of cleavage products. Addition of MASP-1 or thrombin to WB and PPP shortened the clotting time and clot formation time significantly compared to recalcified-only samples. The combination of MASP-1 and thrombin had additive effects. In a purified system, MASP-1 was able to induce clotting only in presence of prothrombin. Analysis of MASP-1-digested prothrombin confirmed that MASP-1 cleaves prothrombin at three cleavage sites. In conclusion, we have shown that MASP-1 is able to induce and promote clot formation measured in a global setting using the technique of thrombelastography. We further confirmed that MASP-1-induced clotting is dependent on prothrombin. Finally, we have demonstrated that MASP-1 cleaves prothrombin and identified its cleavage sites, suggesting that MASP-1 gives rise to an alternative active form of thrombin by cleaving at the cleavage site R393.

Ischemia/reperfusion injury: effect of simultaneous inhibition of plasma cascade systems versus specific complement inhibition.

Ischemia/reperfusion injury (IRI) may occur from ischemia due to thrombotic occlusion, trauma or surgical interventions, including transplantation, with subsequent reestablishment of circulation. Time-dependent molecular and structural changes result from the deprivation of blood and oxygen in the affected tissue during ischemia. Upon restoration of blood flow a multifaceted network of plasma cascades is activated, including the complement-, coagulation-, kinin-, and fibrinolytic system, which plays a major role in the reperfusion-triggered inflammatory process. The plasma cascade systems are therefore promising therapeutic targets for attenuation of IRI. Earlier studies showed beneficial effects through inhibition of the complement system using specific complement inhibitors. However, pivotal roles in IRI are also attributed to other cascades. This raises the question, whether drugs, such as C1 esterase inhibitor, which regulate more than one cascade at a time, have a higher therapeutic potential. The present review discusses different therapeutic approaches ranging from specific complement inhibition to simultaneous inhibition of plasma cascade systems for reduction of IRI, gives an overview of the plasma cascade systems in IRI as well as highlights recent findings in this field.

Quantitative PCR for the diagnosis of cutaneous leishmaniasis from formalin-fixed and paraffin-embedded skin sections.

The present report describes a real-time PCR-based procedure to reliably determine the quantity of Leishmania amastigotes in relation to the amount of host tissue in histological skin sections from canine and equine cases of cutaneous leishmaniasis. The novel diagnostic Leishmania-PCR has a detection limit of <0.02 amastigotes per μg tissue, which corresponds well to the detection limit of immunohistochemistry and is far beyond that of conventional histology. Our results emphasise the importance of PCR to complement routine histology of cutaneous leishmaniasis cases, particularly in laboratories in which no immunohistochemical assay is available.

A Metalloproteinase Mirolysin of Tannerella forsythia Inhibits All Pathways of the Complement System

Recent reports focusing on virulence factors of periodontal pathogens implicated proteinases as major determinants of remarkable pathogenicity of these species, with special emphasis on their capacity to modulate complement activity. In particular, bacteria-mediated cleavage of C5 and subsequent release of C5a seems to be an important phenomenon in the manipulation of the local inflammatory response in periodontitis. In this study, we present mirolysin, a novel metalloproteinase secreted by Tannerella forsythia, a well-recognized pathogen strongly associated with periodontitis. Mirolysin exhibited a strong effect on all complement pathways. It inhibited the classical and lectin complement pathways due to efficient degradation of mannose-binding lectin, ficolin-2, ficolin-3, and C4, whereas inhibition of the alternative pathway was caused by degradation of C5. This specificity toward complement largely resembled the activity of a previously characterized metalloproteinase of T. forsythia, karilysin. Interestingly, mirolysin released the biologically active C5a peptide in human plasma and induced migration of neutrophils. Importantly, we demonstrated that combination of mirolysin with karilysin, as well as a cysteine proteinase of another periodontal pathogen, Prevotella intermedia, resulted in a strong synergistic effect on complement. Furthermore, mutant strains of T. forsythia, devoid of either mirolysin or karilysin, showed diminished survival in human serum, providing further evidence for the synergistic inactivation of complement by these metalloproteinases. Taken together, our findings on interactions of mirolysin with complement significantly add to the understanding of immune evasion strategies of T. forsythia and expand the knowledge on molecular mechanisms driving pathogenic events in the infected periodontium.

Assimilatory Sulfate Reduction in C3, C3-C4, and C4 Species of Flaveria

The activity of the enzymes catalyzing the first two steps of sulfate assimilation, ATP sulfurylase and adenosine 5'-phosphosulfate reductase (APR), are confined to bundle sheath cells in several C4 monocot species. With the aim to analyze the molecular basis of this distribution and to determine whether it was a prerequisite or a consequence of the C4 photosynthetic mechanism, we compared the intercellular distribution of the activity and the mRNA of APR in C3, C3-C4, C4-like, and C4 species of the dicot genusFlaveria. Measurements of APR activity, mRNA level, and protein accumulation in six Flaveria species revealed that APR activity, cysteine, and glutathione levels were significantly higher in C4-like and C4 species than in C3 and C3-C4 species. ATP sulfurylase and APR mRNA were present at comparable levels in both mesophyll and bundle sheath cells of C4 speciesFlaveria trinervia. Immunogold electron microscopy demonstrated the presence of APR protein in chloroplasts of both cell types. These findings, taken together with results from the literature, show that the localization of assimilatory sulfate reduction in the bundle sheath cells is not ubiquitous among C4 plants and therefore is neither a prerequisite nor a consequence of C4photosynthesis.