The determination of food web structures using Ecological Network Analysis (ENA) is a helpful tool to get insight into complex ecosystem processes. The intertidal area of the Wadden Sea is structured ...into diverse habitat types which differ in their ecological functioning. In the present study, six different intertidal habitats (i.e. cockle field, razor clam field, mud flat, mussel bank, sand flat and seagrass meadow) were analyzed using ENA to determine similarities and characteristic differences in the food web structure of the systems. All six systems were well balanced between their degree of organization and their robustness. However, they differed in their detailed features. The cockle field and the mussel bank exhibited a strong dependency on external imports. The razor clam field appeared to be a rather small system with low energy transfer. In the mud flat microphytobenthos was used as a main food source and the system appeared to be sensitive to perturbations. Bird predation was the most pronounced in the sand flat and the seagrass meadow and led to an increase in energy transfer and parallel trophic cycles in these habitats. Habitat diversity appears to be an important trait for the Wadden Sea as each subsystem seems to have a specific role in the overall functioning of the entire ecosystem.
The Wadden Sea is one of the most important stop-over sites for breeding and migrating birds. About 10–12 million birds per year use the area for foraging and consume about 25%–45% of the standing ...stock of macrozoobenthos. However, little is known about the influence of birds on the entire ecosystem.
We conducted ecological network analysis (ENA) on an important bird breeding and resting site, the Norderaue tidal basin in the northern German Wadden Sea, to determine the influence of birds on the entire food web. The model was based on the yearly average biomass of system compartments empirically sampled every season at the study site. The analysis revealed a complex and well-connected food web (high flow diversity and effective link-density) dominated by short pathways but with a high throughput of energy. The system's energy had a high degree of freedom for its development. However, there is a strong dependency on external imports of phytoplankton due to the dominance of suspension feeders suggested by a low recycling and the detritivory to herbivory ratio. A large variety of bird species uses the area for foraging and induces a negative impact on their prey items revealed by the mixed trophic impact analysis. The food sources and also the competitors of the birds' prey items were positively influenced by the birds via indirect pathways in the network. Furthermore, there is a negative impact among the bird compartments probably due to competition between the bird species.
A sensitivity analysis, conducted by changing the bird biomass in the model, revealed only small changes in the activity, complexity and connectivity of the system. The linkage to other system components could amplify these changes in the system functioning. It is therefore recommended to include birds in coastal food web studies which has rarely been done before. The use of holistic approaches such as ENA would facilitate decisions on management measures by providing a simplified representation of the entire ecosystem including all direct and indirect connections between the system components.
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•The Wadden Sea is an important foraging site for breeding and migrating birds.•Influence of birds on food web scale was assessed using ecological network analysis.•Results reveal close linkage of bird compartments to other system components.•Sensitivity analysis applied by changing the bird biomass in the model revealed constant trends but quantitatively small changes in the system indices.•Holistic approaches could be the basis for improving conservation strategies for the Wadden Sea.•Monitoring strategies need to be developed for including top predators properly.
The non-breeding distribution of common scoter (Melanitta nigra), which occur in high densities offshore from the eastern Wadden Sea, has been well documented in recent decades, but factors ...influencing these patterns remain poorly known. We investigated the prey choice of 88 common scoter using stomach contents of beached birds collected over a period of 12 years. We then used benthos data and hydrodynamic parameters to model the June–September distribution patterns during the flightless period of common scoter based on transect count data off the north-eastern German Wadden Sea.
Benthic fauna biomass in areas used by common scoter was higher than in areas where the species was absent. American razor clam (Ensis leei) invaded the Wadden Sea during the end of the 1970s and was the most common prey, both in benthos samples from below feeding common scoter and in stomach samples. The relatively high flesh to shell ratio of the American razor clam makes it the most attractive available prey item for common scoter.
The abundance of American razor clams explained the distribution of scoter to a high degree, although the best model fit included negative effects of water depth and positive effects of bed shear stress intensity on scoter abundance. Our data show that the neobiotic American razor clams have become an important part of the diet of these sea ducks, whereas the cut trough shell (Spisula subtruncata) was of substantially lesser importance than expected from historical data. Our study shows the ability of a top avian predator to respond to novel developments in bivalve prey availability over periods of a few decades.
Neobiotic species can have profound impacts on food webs and entire ecosystems. The American razor clam Ensis leei was introduced into the Wadden Sea by vessels in the late 1970s and has since spread ...widely. It has been suggested that Ensis does not interact strongly with other benthic species. The abundance and biomass of E. leei were recorded in 2393 samples in the north-eastern Wadden Sea and 800 samples in the south-eastern Wadden Sea over a total period of 9 years. Using an interdisciplinary approach, we developed a habitat prediction model using sedimentological and hydrodynamic predictors to help understand the shape of the ecological niche occupied by Ensis in the Wadden Sea. Our model showed that Ensis preferred areas with moderately high bed shear stress and prolonged or constant water coverage. Ensis preferred coarse sediments in the northern sub-area but coarse and muddy sediments in the southern sub-area and was negatively affected by the sand mason worm Lanice conchilega in the northern sub-area. Predictions of the spatial distribution of Ensis using the northern and southern datasets revealed major differences in predicted hot-spots throughout the entire study site. This study thus highlights the need to collect a sufficiently large dataset from different sub-areas of the Wadden Sea to allow valid conclusions to be drawn regarding the spatial distribution of Ensis. The negative effects of L. conchilega on Ensis abundance and biomass as well as the occurrence of Ensis in muddy sediments in the south suggest that the ecological niche of this neobiotic species is likely to overlap partly with the native fauna of the Wadden Sea.
•Long-term data were used to determine ecological niche and predict habitat potential of Ensis leei.•Abundance and biomass of Ensis were related with sedimentologic and hydrodanamic predictors.•Ensis occurred both, in coarse sediments as well as in muddy environments.•Ensis abundance and biomass declined in areas with dense Lanice conchilega reefs.•The invasive Ensis is thought to overlap with the pristine benthic fauna particularly in muddy sediments.
Preeclampsia is a severe complication of pregnancy. Antiangiogenic factors soluble fms-like tyrosine kinase-1 (sFlt-1) and soluble endoglin are secreted in excess from the placenta, causing ...hypertension, endothelial dysfunction, and multiorgan injury. Oxidative stress and vascular inflammation exacerbate the endothelial injury. A drug that can block these pathophysiological steps would be an attractive treatment option. Proton pump inhibitors (PPIs) are safe in pregnancy where they are prescribed for gastric reflux. We performed functional studies on primary human tissues and animal models to examine the effects of PPIs on sFlt-1 and soluble endoglin secretion, vessel dilatation, blood pressure, and endothelial dysfunction. PPIs decreased sFlt-1 and soluble endoglin secretion from trophoblast, placental explants from preeclamptic pregnancies, and endothelial cells. They also mitigated tumor necrosis factor-α–induced endothelial dysfunctionPPIs blocked endothelial vascular cell adhesion molecule-1 expression, leukocyte adhesion to endothelium, and disruption of endothelial tube formation. PPIs decreased endothelin-1 secretion and enhanced endothelial cell migration. Interestingly, the PPI esomeprazole vasodilated maternal blood vessels from normal pregnancies and cases of preterm preeclampsia, but its vasodilatory effects were lost when the vessels were denuded of their endothelium. Esomeprazole decreased blood pressure in a transgenic mouse model where human sFlt-1 was overexpressed in placenta. PPIs upregulated endogenous antioxidant defenses and decreased cytokine secretion from placental tissue and endothelial cells. We have found that PPIs decrease sFlt-1 and soluble endoglin secretion and endothelial dysfunction, dilate blood vessels, decrease blood pressure, and have antioxidant and anti-inflammatory properties. They have therapeutic potential for preeclampsia and other diseases where endothelial dysfunction is involved.
In preeclampsia, the antiangiogenic factor soluble fms-like tyrosine kinase-1 (sFLT-1) is released from placenta into the maternal circulation, causing endothelial dysfunction and organ injury. A ...recently described splice variant, sFLT-1 e15a, is primate specific and the most abundant placentally derived sFLT-1. Therefore, it may be the major sFLT-1 isoform contributing to the pathophysiology of preeclampsia. sFLT-1 e15a protein remains poorly characterized: its bioactivity has not been comprehensively examined, and serum levels in normal and preeclamptic pregnancy have not been reported. We generated and validated an sFLT-1 e15a-specific ELISA to further characterize serum levels during pregnancy, and in the presence of preeclampsia. Furthermore, we performed assays to examine the bioactivity and antiangiogenic properties of sFLT-1 e15a protein. sFLT-1 e15a was expressed in the syncytiotrophoblast, and serum levels rose across pregnancy. Strikingly, serum levels were increased 10-fold in preterm preeclampsia compared with normotensive controls. We confirmed sFLT-1 e15a is bioactive and is able to inhibit vascular endothelial growth factor signaling of vascular endothelial growth factor receptor 2 and block downstream Akt phosphorylation. Furthermore, sFLT-1 e15a has antiangiogenic properties. sFLT-1 e15a decreased endothelial cell migration, invasion, and inhibited endothelial cell tube formation. Administering sFLT-1 e15a blocked vascular endothelial growth factor induced sprouts from mouse aortic rings ex vivo. We have demonstrated that sFLT-1 e15a is increased in preeclampsia, antagonizes vascular endothelial growth factor signaling, and has antiangiogenic activity. Future development of diagnostics and therapeutics for preeclampsia should consider targeting placentally derived sFLT-1 e15a.
The transformation of functional proteins into amyloidic plaques is responsible for the impairment of neurological functions in patients fallen victim to debilitating neurological conditions like ...Alzheimer's, Parkinson's, and Huntington's diseases. The nucleating role of amyloid beta (Aβ1‐40) peptide into amyloids is well established. Herein, lipid hybrid‐vesicles are generated with glycerol/cholesterol‐bearing polymers aiming to alter the nucleation process and modulate the early phases of Aβ1‐40 fibrillation. Hybrid‐vesicles (±100 nm) are prepared by incorporating variable amounts of cholesterol‐/glycerol‐conjugated poly(di(ethylene glycol)macrylates)n polymers into 1,2‐dioleoyl‐sn‐glycero‐3‐phosphocholine (DOPC) membranes. The in vitro fibrillation kinetics coupled to transmission electron microscopy (TEM) is employed to investigate the role of hybrid‐vesicles on Aβ1‐40 fibrillation without destroying the vesicular membrane. Both polymers, when embedded in hybrid‐vesicles (up to 20%) significantly prolonged the fibrillation lag phase (tlag) compared to a small acceleration in the presence of DOPC vesicles, irrespective of the amount of polymers inside the hybrid‐vesicles. Along with this notable retardation effect, a morphological transformation of the amyloid's secondary structures to amorphous aggregates or the absence of fibrillar structures when interacting with the hybrid‐vesicles is confirmed by TEM and circular dichroism (CD) spectroscopy.
The transformation of functional proteins into amyloidic plaques is responsible for the impairment of neurological functions in patients fallen victim to debilitating neurological conditions like ...Alzheimer's, Parkinson's, and Huntington's diseases. The nucleating role of amyloid beta (Aβ
) peptide into amyloids is well established. Herein, lipid hybrid-vesicles are generated with glycerol/cholesterol-bearing polymers aiming to alter the nucleation process and modulate the early phases of Aβ
fibrillation. Hybrid-vesicles (±100 nm) are prepared by incorporating variable amounts of cholesterol-/glycerol-conjugated poly(di(ethylene glycol)
acrylates)
polymers into 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) membranes. The in vitro fibrillation kinetics coupled to transmission electron microscopy (TEM) is employed to investigate the role of hybrid-vesicles on Aβ
fibrillation without destroying the vesicular membrane. Both polymers, when embedded in hybrid-vesicles (up to 20%) significantly prolonged the fibrillation lag phase (t
) compared to a small acceleration in the presence of DOPC vesicles, irrespective of the amount of polymers inside the hybrid-vesicles. Along with this notable retardation effect, a morphological transformation of the amyloid's secondary structures to amorphous aggregates or the absence of fibrillar structures when interacting with the hybrid-vesicles is confirmed by TEM and circular dichroism (CD) spectroscopy.
The molecular recognition between cholera toxin B and GM1‐functionalized phospholipid/block copolymer hybrid membranes can be controlled by varying the lipid/block copolymer composition. Confocal ...laser scanning microscopy and fluorescence correlation spectroscopy were used to study the protein–receptor interaction and dynamic processes in the membrane.
ObjectivesEarly diagnosis of inflammatory arthritis is critical to prevent joint damage and functional incapacities. However, the discrepancy between recommendations of early diagnosis and reality is ...remarkable. The Rheuma-VOR study aimed to improve the time to diagnosis of patients with early arthritis by coordinating cooperation between primary care physicians, specialists and patients in Germany.MethodsThis prospective non-randomised multicentre study involved 2340 primary care physicians, 72 rheumatologists, 4 university hospitals and 4 rheumatology centres in 4 German Federal States. The two coprimary endpoints (time to diagnosis and screening performance of primary care physicians) were evaluated for early versus late implementation phase. Additionally, time to diagnosis and secondary endpoints (decrease of disease activity, increase in quality of life and overall well-being, improvement of fatigue, depression, functional ability, and work ability, reduction in drug and medical costs and hospitalisation) were compared with a reference cohort of the German Rheumatism Research Centre (DRFZ) reflecting standard care.ResultsA total of 7049 patients were enrolled in the coordination centres and 1537 patients were diagnosed with a rheumatic disease and consented to further participation. A follow-up consultation after 1 year was realised in 592 patients. The time to diagnosis endpoint and the secondary endpoints were met. In addition, the calculation of cost-effectiveness shows that Rheuma-VOR has a dominant cost–benefit ratio compared with standard care.DiscussionRheuma-VOR has shown an improvement in rheumatological care, patient-reported outcome parameters and cost savings by coordinating the cooperation of primary care physicians, rheumatologists and patients, in a nationwide approach.
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