Untersuchungen zur Biologie und Ökologie der stark gefährdeten Halbstrauch-Radmelde (Bassia prostrata) in Österreich als Beitrag zur Entwicklung von Schutzmaßnahmen

Mit der Feinkartierung der Vorkommen von Bassia prostrata im Untersuchungsgebiet konnten die bisher in der Fachliteratur angegebenen Fundorte bestätigt, in einem Fall als erloschen korrigiert, und in 5 weiteren Fällen um neue Fundorte erweitert werden. Die flächenscharfe kartografische Darstellung der Bassia-Biotope, sowie der umgebenden Landschaftsstrukturelemente stellt eine genaue Momentaufnahme von Art-Verbreitung und Einbettung in die Kulturlandschaft dar, was die weitere Entwicklung der Vorkommen genau verfolgen lässt. Die in der Biotopkartierung erhobenen Daten zu Vegetationsstruktur und Bestandesstruktur von Bassia prostrata komplettieren die Darstellung. Zumindest auf der Ebene der eingerichteten Monitoringflächen wird das im Rahmen des vom Niederösterreichischen Landschaftsfond geförderten Artenschutzprojektes bis Ende 2009 erfolgen. Die Erhebung von Vegetation und demografischen Daten hat mehrere Habitattypen für Bassia prostrata ergeben, von denen die wichtigsten die Lockersedimentkantenflur, der Ruderale Mittelgrasrasen, der lückige Kurzgrasrasen sind. Der Habitattyp Gehölzbestände beschreibt die Gefährdungssituation durch Verbuschung, die anderen Randtypen sind großteils ephemere Erscheinungen. Die Charakteristik von Bassia prostrata als Steppen-, Halbwüsten- bis Wüstenpflanze spiegelt sich in den standörtlichen Faktoren wieder, die für das Vorkommen der Art gleichermaßen ausschlaggebend sind: ausreichend ● Trockenheit, ● Wärme, ● Licht und ● offener Boden. In qualitativer Hinsicht kann das folgendermaßen zusammengefasst werden: 1.) Das Gebiet Retz-Haugdorf hat warme Temperaturen, die geringsten Niederschläge Österreichs, eine hohe Sonnenscheindauer, es gehört der subpannonischen Klimazone an. 2.) Es konnte deutlich gezeigt werden, dass es sich zum Großteil um SW-exponierte Standorte handelt. 3.) Zumeist sind es Böschungen mit Kulturrohboden. Die Böden sind hauptsächlich kalkhaltig, siltig und erosiv, drei Eigenschaften, die z.B. Löss erfüllt. Bassia prostrata kommt aber auch auf kalkhaltigen Feinsanden der Laa-Formation, sowie kalkfreien Böden, v.a. der marinen Zellerndorf-Formation vor. Eine edaphische Bindung an Löss (WENDELBERGER 1954, 1959, 1976) besteht also nicht in physiologischem Sinne, sondern ist nur ein pflanzengeografisch-historisches Konzept zur Erklärung der Arealgenese. Die "Lössrelikttheorie" ist damit keineswegs widerlegt, sondern nur relativiert. 4.) Die Standorte sind von starken kleinklimatischen Extremata geprägt; im Sommer herrscht meist große Hitze, im Winter ist der Boden bisweilen bis 25 cm tief gefroren, eine Schneedecke ist fast nicht vorhanden, da sie vom Wind und der Wintersonne dezimiert wird. 5.) Bassia prostrata braucht für die Regeneration ihrer Bestände offene Böden. In Beständen mit geschlossener Krautschicht, zu starker Streuschicht (bzw. zu starkem Rasenfilz) oder auch Beschattung durch Gehölze ist die Verjüngung (die Etablierung der Keim- und Jungpflanzen) bald stark reduziert. Bassia prostrata kann sich mit den älteren Individuen zwar noch einige Zeit halten, verschwindet aber mittelfristig. (5a) Diese lückigen, offenen Böden schafft entweder die erosive Eigenschaft des Substrats selbst, oder die Inklination. Auf stärker erosiven Böden (Feinsand) werden auch weniger stark geneigte Flächen besiedelt, Lösslehm erodiert merklich ab etwa 35°. (5b) Offensichtlich ist auch der Zusammenhang mit zoogener Störung, v.a. ist hier die wühlende Rolle des Wild-Kaninchens, aber auch das Vorhandensein von Wildwechseln zu nennen, entlang derer Bassia prostrata auf neu besiedelten Flächen als erste vorkommt. (5c) Die anthropogene Störung ist ein wesentlicher Faktor für das Vorkommen von Bassia prostrata. Zum einen in historischer Hinsicht, denn alle Biotope sind anthropogen bzw. anthropogen überformt. Der Großeil der heutigen Bestände kommt im Bereich der Weingartenlandschaft, auf Terrassenböschungen vor, egal ob zwischen Weingärten oder entlang von Güterwegen. Die menschliche Nutzung sorgt auch heute noch für reichlich Keimstellen, von denen auch Teile als Schutzstellen (safe-sites) übrig bleiben. Besonders sind dabei die Randzonen der Weingarten-Wendebereiche zu nennen. Andererseits ist der Nutzungsdruck aber auch fallweise für den Verlust von Beständen oder Teilen davon verantwortlich. Vorkommen auf anderen anthropogen gestörten Standorten wie gemulchten und leicht aufgerissenen Straßenböschungen, in regelmäßig gemähten Gärten, auf Weinkellerportalen, Trockenmauern oder Pflasterritzen am Gehsteigbordrand bis hin zu Kanaldeckellücken oder Banketten sind kuriose Einzelerscheinungen, langfristig aber nicht bestandessichernd. 6.) Die größte Gefährdung /Beeinträchtigung für die Bestände von Bassia prostrata geht von der Verbuschung aus, inbesondere und in hohem Maße von den beiden invasiven Neophyten Robinia pseudacacia (Robinie, "Akazie") und Lycium barbarum (Bocksdorn, "Judenfelber"). Die Situation ist in mehreren Fällen schon sehr kritisch. Einzelereignisse wie Geländekorrekturen, Abgrabungen, Neuanlagen von Weingärten sollten auf den Erhalt der Bassia prostrata–Bestände Rücksicht nehmen. Ein Konzept zum Biotopmanagement sollte nicht nur einmalige und lokal begrenzte Behübschungsmaßnahmen umfassen, sondern nachhaltig und größerräumig wirken. Außerdem sollte es die Trockenhänge als Biotopkomplex erfassen, und somit auch die naturschutzfachlich noch wertvolleren Vorkommen von Arten wie Astragalus vesicarius subsp. vesicarius, Orobanche caerulescens, Orobanche teucrii erfassen. 7.) Mit der Ansalbung an der 2006 eröffneten S3 Weinviertler Schnellstraße konnte neben den Ergebnissen zur wissenschaftlichen Untersuchung auch ein arealkundlich akzeptabler, kleiner Beitrag zur Sicherung des Bassia prostrata-Bestandes in Österreich gemacht, eine Verbesserung des Erosionsschutzes an Straßenbegleitflächen erzielt, und die Straßenbegleitvegetation auch um ein kleines bisschen naturnäher gemacht werden. 8.) Zur Autökologie (Reproduktionsbiologie, vegetativen Biologie) von Bassia prostrata, und ihrer Populationsbiologie konnten keine wesentlichen, neuen Kenntnisse gewonnen werden, außer dass diese für die österreichischen Vorkommen dargestellt wurden. Die reichlich in der Literatur angegebenen Daten wurden aber zum Großteil bestätigt

Spectral asymptotics of the Laplacian on supercritical bond-percolation graphs

We investigate Laplacians on supercritical bond-percolation graphs with different boundary conditions at cluster borders. The integrated density of states of the Dirichlet Laplacian is found to exhibit a Lifshits tail at the lower spectral edge, while that of the Neumann Laplacian shows a van Hove asymptotics, which results from the percolating cluster. At the upper spectral edge, the behaviour is reversed.Comment: 16 pages, typos corrected, to appear in J. Funct. Ana

miR-125b induces cellular senescence in malignant melanoma

BACKGROUND: Micro RNAs (miRs) have emerged as key regulators during oncogenesis. They have been found to regulate cell proliferation, differentiation, and apoptosis. Mir-125b has been identified as an oncomir in various forms of tumours, but we have previously proposed that miR-125b is a suppressor of lymph node metastasis in cutaneous malignant melanoma. Our goal was therefore to further examine this theory. METHODS: We used in-situ-hybridization to visualise miR-125b expression in primary tumours and in lymph node metastasis. Then using a miRVector plasmid containing a miR-125b-1 insert we transfected melanoma cell line Mel-Juso and then investigated the effect of the presence of a stable overexpression of miR-125b on growth by western blotting, flow cytometry and β-galactosidase staining. The tumourogenicity of the transfected cells was tested using a murine model and the tumours were further examined with in-situ-hybridization. RESULTS: In primary human tumours and in lymph node metastases increased expression of miR-125b was found in single, large tumour cells with abundant cytoplasm. A stable overexpression of miR-125b in human melanoma cell line Mel-Juso resulted in a G0/G1 cell cycle block and emergence of large cells expressing senescence markers: senescence-associated beta-galactosidase, p21, p27 and p53. Mel-Juso cells overexpressing miR-125b were tumourigenic in mice, but the tumours exhibited higher level of cell senescence and decreased expression of proliferation markers, cyclin D1 and Ki67 than the control tumours. CONCLUSIONS: Our results confirm the theory that miR-125b functions as a tumour supressor in cutaneous malignant melanoma by regulating cellular senescence, which is one of the central mechanisms protecting against the development and progression of malignant melanoma

Two-dimensional SIR epidemics with long range infection

We extend a recent study of susceptible-infected-removed epidemic processes with long range infection (referred to as I in the following) from 1-dimensional lattices to lattices in two dimensions. As in I we use hashing to simulate very large lattices for which finite size effects can be neglected, in spite of the assumed power law $p({\bf x})\sim |{\bf x}|^{-\sigma-2}$ for the probability that a site can infect another site a distance vector ${\bf x}$ apart. As in I we present detailed results for the critical case, for the supercritical case with $\sigma = 2$, and for the supercritical case with $0< \sigma < 2$. For the latter we verify the stretched exponential growth of the infected cluster with time predicted by M. Biskup. For $\sigma=2$ we find generic power laws with $\sigma-$dependent exponents in the supercritical phase, but no Kosterlitz-Thouless (KT) like critical point as in 1-d. Instead of diverging exponentially with the distance from the critical point, the correlation length increases with an inverse power, as in an ordinary critical point. Finally we study the dependence of the critical exponents on $\sigma$ in the regime $0<\sigma <2$, and compare with field theoretic predictions. In particular we discuss in detail whether the critical behavior for $\sigma$ slightly less than 2 is in the short range universality class, as conjectured recently by F. Linder {\it et al.}. As in I we also consider a modified version of the model where only some of the contacts are long range, the others being between nearest neighbors. If the number of the latter reaches the percolation threshold, the critical behavior is changed but the supercritical behavior stays qualitatively the same.Comment: 14 pages, including 29 figure

In-vitro and in-vivo degradation studies of freeze gelated porous chitosan composite scaffolds for tissue engineering applications

Tissue engineering approaches have been adapted to reconstruct and restore functionality of impaired tissue for decades. Porous biomimetic composite scaffolds of Chitosan (CH) with hydroxyapatite (HA) for bone regeneration have also been extensively studied in the past. These porous scaffolds play a critical role in providing successful regeneration by acting as a three-dimensional template for delivering nutrients and metabolites and the removal of waste by products. The aim of the current study was to investigate in-vitro and in-vivo degradation rates of porous freeze gelated chitosan (CH) and CH hydroxyapatite scaffolds by scanning electron microscopy (SEM) to observe for morphological changes, Fourier Transform Infrared Spectroscopy (FTIR) in conjunction with photo-acoustic sampling (PAS) accessory for the analysis of chemical changes, pH analysis and UV–Vis spectroscopy of degraded supernatant. SEM results showed significant alterations in the surface morphology. FTIR-PAS spectra showed changes in the finger print region and glycosidic bonds showed signs of breakage. pH values and UV–Vis spectroscopy of the degraded supernatant were indicative of CH bonds scission in neat samples. HA incorporated specimens showed more stability. Histological sections performed after in-vivo implantation also showed greater cellular infiltration and delayed degradation profiles by HA loaded samples. Within 30 days of implantation, neat CH scaffolds showed complete in-vivo biodegradation. The current findings show the advantage of adding hydroxyapatite to porous templates which enhances hard tissue regeneration. In addition, it allows easy and cost effective fabrication of bioactive composite scaffolds

Gene family information facilitates variant interpretation and identification of disease-associated genes in neurodevelopmental disorders

Abstract Background Classifying pathogenicity of missense variants represents a major challenge in clinical practice during the diagnoses of rare and genetic heterogeneous neurodevelopmental disorders (NDDs). While orthologous gene conservation is commonly employed in variant annotation, approximately 80% of known disease-associated genes belong to gene families. The use of gene family information for disease gene discovery and variant interpretation has not yet been investigated on a genome-wide scale. We empirically evaluate whether paralog-conserved or non-conserved sites in human gene families are important in NDDs. Methods Gene family information was collected from Ensembl. Paralog-conserved sites were defined based on paralog sequence alignments; 10,068 NDD patients and 2078 controls were statistically evaluated for de novo variant burden in gene families. Results We demonstrate that disease-associated missense variants are enriched at paralog-conserved sites across all disease groups and inheritance models tested. We developed a gene family de novo enrichment framework that identified 43 exome-wide enriched gene families including 98 de novo variant carrying genes in NDD patients of which 28 represent novel candidate genes for NDD which are brain expressed and under evolutionary constraint. Conclusion This study represents the first method to incorporate gene family information into a statistical framework to interpret variant data for NDDs and to discover new NDD-associated genes

Monte Carlo Methods for Estimating Interfacial Free Energies and Line Tensions

Excess contributions to the free energy due to interfaces occur for many problems encountered in the statistical physics of condensed matter when coexistence between different phases is possible (e.g. wetting phenomena, nucleation, crystal growth, etc.). This article reviews two methods to estimate both interfacial free energies and line tensions by Monte Carlo simulations of simple models, (e.g. the Ising model, a symmetrical binary Lennard-Jones fluid exhibiting a miscibility gap, and a simple Lennard-Jones fluid). One method is based on thermodynamic integration. This method is useful to study flat and inclined interfaces for Ising lattices, allowing also the estimation of line tensions of three-phase contact lines, when the interfaces meet walls (where "surface fields" may act). A generalization to off-lattice systems is described as well. The second method is based on the sampling of the order parameter distribution of the system throughout the two-phase coexistence region of the model. Both the interface free energies of flat interfaces and of (spherical or cylindrical) droplets (or bubbles) can be estimated, including also systems with walls, where sphere-cap shaped wall-attached droplets occur. The curvature-dependence of the interfacial free energy is discussed, and estimates for the line tensions are compared to results from the thermodynamic integration method. Basic limitations of all these methods are critically discussed, and an outlook on other approaches is given

Aberrant phase separation and nucleolar dysfunction in rare genetic diseases

Thousands of genetic variants in protein-coding genes have been linked to disease. However, the functional impact of most variants is unknown as they occur within intrinsically disordered protein regions that have poorly defined functions1-3. Intrinsically disordered regions can mediate phase separation and the formation of biomolecular condensates, such as the nucleolus4,5. This suggests that mutations in disordered proteins may alter condensate properties and function6-8. Here we show that a subset of disease-associated variants in disordered regions alter phase separation, cause mispartitioning into the nucleolus and disrupt nucleolar function. We discover de novo frameshift variants in HMGB1 that cause brachyphalangy, polydactyly and tibial aplasia syndrome, a rare complex malformation syndrome. The frameshifts replace the intrinsically disordered acidic tail of HMGB1 with an arginine-rich basic tail. The mutant tail alters HMGB1 phase separation, enhances its partitioning into the nucleolus and causes nucleolar dysfunction. We built a catalogue of more than 200,000 variants in disordered carboxy-terminal tails and identified more than 600 frameshifts that create arginine-rich basic tails in transcription factors and other proteins. For 12 out of the 13 disease-associated variants tested, the mutation enhanced partitioning into the nucleolus, and several variants altered rRNA biogenesis. These data identify the cause of a rare complex syndrome and suggest that a large number of genetic variants may dysregulate nucleoli and other biomolecular condensates in humans.© 2023. The Author(s)

Delineating the GRIN1 phenotypic spectrum: a distinct genetic NMDA receptor encephalopathy

Objective:To determine the phenotypic spectrum caused by mutations in GRIN1 encoding the NMDA receptor subunit GluN1 and to investigate their underlying functional pathophysiology.Methods:We collected molecular and clinical data from several diagnostic and research cohorts. Functional consequences of GRIN1 mutations were investigated in Xenopus laevis oocytes.Results:We identified heterozygous de novo GRIN1 mutations in 14 individuals and reviewed the phenotypes of all 9 previously reported patients. These 23 individuals presented with a distinct phenotype of profound developmental delay, severe intellectual disability with absent speech, muscular hypotonia, hyperkinetic movement disorder, oculogyric crises, cortical blindness, generalized cerebral atrophy, and epilepsy. Mutations cluster within transmembrane segments and result in loss of channel function of varying severity with a dominant-negative effect. In addition, we describe 2 homozygous GRIN1 mutations (1 missense, 1 truncation), each segregating with severe neurodevelopmental phenotypes in consanguineous families.Conclusions:De novo GRIN1 mutations are associated with severe intellectual disability with cortical visual impairment as well as oculomotor and movement disorders being discriminating phenotypic features. Loss of NMDA receptor function appears to be the underlying disease mechanism. The identification of both heterozygous and homozygous mutations blurs the borders of dominant and recessive inheritance of GRIN1-associated disorders.Johannes R. Lemke (32EP30_136042/1) and Peter De Jonghe (G.A.136.11.N and FWO/ESF-ECRP) received financial support within the EuroEPINOMICS-RES network (www.euroepinomics.org) within the Eurocores framework of the European Science Foundation (ESF). Saskia Biskup and Henrike Heyne received financial support from the German Federal Ministry for Education and Research (BMBF IonNeurONet: 01 GM1105A and FKZ: 01EO1501). Katia Hardies is a PhD fellow of the Institute for Science and Technology (IWT) Flanders. Ingo Helbig was supported by intramural funds of the University of Kiel, by a grant from the German Research Foundation (HE5415/3-1) within the EuroEPINOMICS framework of the European Science Foundation, and additional grants of the German Research Foundation (DFG, HE5415/5-1, HE 5415/6-1), German Ministry for Education and Research (01DH12033, MAR 10/012), and grant by the German chapter of the International League against Epilepsy (DGfE). The project also received infrastructural support through the Institute of Clinical Molecular Biology in Kiel, supported in part by DFG Cluster of Excellence "Inflammation at Interfaces" and "Future Ocean." The project was also supported by the popgen 2.0 network (P2N) through a grant from the German Ministry for Education and Research (01EY1103) and by the International Coordination Action (ICA) grant G0E8614N. Christel Depienne, Caroline Nava, and Delphine Heron received financial support for exome analyses by the Centre National de Genotypage (CNG, Evry, France)