| 1. |
- Altewischer, Andrea, et al.
(author)
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Habitat preferences of male Corn Buntings Emberiza calandra in north-eastern Germany
- 2015
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In: Acta Ornithologica. - 0001-6454 .- 1734-8471. ; 50:1, s. 1-10
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Journal article (peer-reviewed)abstract
- Agricultural ecosystems have faced dramatic changes during past decades, resulting in a dramatic loss of farmland biodiversity. The Corn Bunting Emberiza calandra is considered a suitable indicator for the conservation value of farmland habitats, and has recently suffered strong declines throughout much of its European range. As a basis for targeted conservation measures, we investigated the habitat preferences of this species in north-eastern Germany by comparing the composition of male territories with randomly chosen control sites. A territory was defined as the area within a radius of 150 meters around the assumed centre of the territory, as the majority of nests is found within this radius. To assess food availability for nestlings, arthropod abundance within the most abundant land use types i.e. crop fields, fallows, grassland as well as within unploughed strips was investigated. In total we found 102 male Corn Bunting territories, which were mainly composed of crop fields (50%), grassland (28%), and fallows (12%). Territories compared with control sites were characterized by a lower proportion of crop fields, a higher proportion of fallows, more diverse land use types, more abundant field boundaries, unploughed strips, and tracks, and a higher availability of song posts. However, neither the number of larger (≥ 1 cm), smaller (< 1 cm) or all arthropods differed significantly among analysed land use types i.e. crop fields, fallows, grassland, unploughed strips. Our study confirms the significance of habitat heterogeneity and especially of sites with sparse vegetation (fallows > 10%) and song posts (> 70 m ‘linear song posts’ or > 1 solitary post per ha) for the habitat selection of male Corn Buntings. We conclude that measures to halt population declines of Corn Buntings seem to be relatively easy to implement, provided that farmers are granted a fair compensation.
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| 2. |
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| 3. |
- Liu, Kang-Cheng, et al.
(author)
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Membrane insertion mechanism of the caveola coat protein Cavin1
- 2022
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In: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 119:25
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Journal article (peer-reviewed)abstract
- Caveolae are small plasma membrane invaginations, important for control of membrane tension, signaling cascades, and lipid sorting. The caveola coat protein Cavin1 is essential for shaping such high curvature membrane structures. Yet, a mechanistic understanding of how Cavin1 assembles at the membrane interface is lacking. Here, we used model membranes combined with biophysical dissection and computational modeling to show that Cavin1 inserts into membranes. We establish that initial phosphatidylinositol (4, 5) bisphosphate [PI(4,5)P2]-dependent membrane adsorption of the trimeric helical region 1 (HR1) of Cavin1 mediates the subsequent partial separation and membrane insertion of the individual helices. Insertion kinetics of HR1 is further enhanced by the presence of flanking negatively charged disordered regions, which was found important for the coassembly of Cavin1 with Caveolin1 in living cells. We propose that this intricate mechanism potentiates membrane curvature generation and facilitates dynamic rounds of assembly and disassembly of Cavin1 at the membrane.
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| 4. |
- Reuter, Marcel, et al.
(author)
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Poly-L-lysines and poly-L-arginines induce leakage of negatively charged phospholipid vesicles and translocate through the lipid bilayer upon electrostatic binding to the membrane
- 2009
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In: Biophysical Chemistry. - : Elsevier BV. - 0301-4622 .- 1873-4200. ; 144:1-2, s. 27-37
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Journal article (peer-reviewed)abstract
- Poly-lysines (PLL) and poly-arginines (PLA) of different polymer chain lengths interact strongly with neg. charged phospholipid vesicles mainly due to their different elec. charges. 1-Palmitoyl-2-oleoyl-sn-glycero-3-phosphoglycerol (POPG), 1,2-dipalmitoyl-sn-glycero-3-phosphoglycerol (DPPG) and their mixts. (1/1 mol/mol) with the resp. phosphatidylcholines of equiv. chain length were chosen as model membrane systems that form at room temp. either the fluid Lalpha or the gel phase Lbeta lipid bilayer membranes, resp. Leakage expts. revealed that the fluid POPG membranes are more perturbed compared to the gel phase DPPG membranes upon peptide binding. Furthermore, it was found that pure PG membranes are more prone to release the vesicle contents as a result of pore formation than the lipid mixts. POPG/POPC and DPPG/DPPC. For the longer polymers (>= 44 amino acids) maximal dye-release was obsd. when the molar ratio of the concns. of amino acid residues to charged lipid mols. reached a value of R P = 0.5, i.e. when the outer membrane layer was theor. entirely covered by the polymer. At ratios lower or higher than 0.5 leakage dropped significantly. Furthermore, PLL and PLA insertions and/or translocations through lipid membranes were analyzed by using FITC-labeled polymers by monitoring their fluorescence intensity upon membrane binding. Short PLL mols. and PLA mols. of all lengths seemed to translocate through both fluid and gel phase lipid bilayers. Comparison of the PLL and PLA fluorescence assay results showed that PLA interacts stronger with phospholipid membranes compared to PLL. Isothermal titrn. calorimetry (ITC) measurements were performed to give further insight into these mechanisms and to support the findings obtained by fluorescence assays. Cryo-transmission electron microscopy (cryo-TEM) was used to visualize changes in the vesicles' morphol. after addn. of the polypeptides.
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| 5. |
- von Zur-Mühlen, Bengt, Docent, 1966-, et al.
(author)
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Open Randomized Multicenter Study to Evaluate Safety and Efficacy of Low Molecular Weight Sulfated Dextran in Islet Transplantation
- 2019
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In: Transplantation. - : LIPPINCOTT WILLIAMS & WILKINS. - 0041-1337 .- 1534-6080. ; 103:3, s. 630-637
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Journal article (peer-reviewed)abstract
- Background. When transplanted human pancreatic islets are exposed to blood during intraportal infusion, an innate immune response is triggered. This instant blood-mediated inflammatory reaction (IBMIR) activates the coagulation and complement cascades and leads to the destruction of 25% of all transplanted islets within minutes, contributing to the need, in most patients, for islets from more than 1 donor. Low molecular dextran sulfate (LMW-DS) has been shown in experimental settings to inhibit IBMIR. Methods. The Clinical Islet Transplantation consortium 01 study was a phase II, multicenter, open label, active control, randomized study. Twenty-four subjects were randomized to peritransplant intraportal and systemic treatment with either LMW-DS or heparin, targeting an activated partial thromboplastin time of 150 +/- 10 seconds and 50 +/- 5 seconds, respectively. C-peptide response was measured with a mixed meal tolerance test at 75 and 365 days after transplant. Results. Low molecular dextran sulfate was safe and well tolerated with similar observed adverse events (mostly attributed to immunosuppression) as in the heparin arm. There was no difference in the primary endpoint (stimulated C-peptide 75 +/- 5 days after the first transplant) between the 2 arms (1.33 +/- 1.10 versus 1.56 +/- 1.36 ng/mL, P = 0.66). Insulin requirement, metabolic parameters, Clarke and HYPO score, quality of life, and safety were similar between the 2 treatments groups. Conclusions. Even with low dosing, LMW-DS showed similar efficacy in preventing IBMIR to promote islet engraftment when compared to "state-of-the art" treatment with heparin. Furthermore, no substantial differences in the efficacy and safety endpoints were detected, providing important information for future studies with more optimal dosing of LMW-DS for the prevention of IBMIR in islet transplantation.
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