Linkages between Phosphorus and Plant Diversity in Central European Forest Ecosystems—Complementarity or Competition?

The phosphorus nutrition status of European forests has decreased significantly in recent decades. For a deeper understanding of complementarity and competition in terms of P acquisition in temperate forests, we have analyzed α-diversity, organic layer and mineral soil P, P nutrition status, and different concepts of P use efficiency (PUE) in Fagus sylvatica L. (European beech) and Picea abies (L.) H. Karst. (Norway spruce). Using a subset of the Second National Soil Survey in Germany, we correlated available data on P in the organic layer and soil with α-diversity indices for beech and spruce forests overall and for individual vegetation layers (tree, shrub, herb, and moss layers). Moreover, we investigated α-diversity feedbacks on P nutrition status and PUE of both tree species. The overall diversity of both forest ecosystems was largely positively related to P content in the organic layer and soil, but there were differences among the vegetation layers. Diversity in the tree layer of both forest ecosystems was negatively related to the organic layer and soil P. By contrast, shrub diversity showed no correlation to P, while herb layer diversity was negatively related to P in the organic layer but positively to P in soil. A higher tree layer diversity was slightly related to increased P recycling efficiency (PPlant/Porganic layer) in European beech and P uptake efficiency (PPlant/Psoil) in Norway spruce. The diversity in the herb layer was negatively related to P recycling and uptake efficiency in European beech and slightly related to P uptake efficiency in Norway spruce. In spruce forests, overall and herb species richness led to significantly improved tree nutrition status. Our results confirm significant, non-universal relationships between P and diversity in temperate forests with variations among forest ecosystems, vegetation layers, and P in the organic layer or soil. In particular, tree species diversity may enhance complementarity and hence also P nutrition of dominant forest trees through higher PUE, whereas moss and herb layers seemed to show competitive relationships among each other in nutrient cycling.DFG, 241127382, PhosForDiv - Phosphatverfügbarkeit als Einflussgröße der Pflanzen-Biodiversität in Waldökosysteme

Nitric oxide modulates the angiogenic phenotype of middle-T transformed endothelial cells.

The role of nitric oxide (NO) in the induction of angiogenesis was evaluated in a murine heart endothelioma cell line (H.end.FB) carrying the mT oncogene. Two clonal derivatives of H.end.FB, H80 and H73, exhibiting different NO synthase (NOS) activities were selected and used in the study. The relationship among NOS activity and tumor cell behaviour (growth, and angiogenic capacity) and the molecular control of gene expression were investigated. H.end.FB and H80 on one side and H73 on the other side exhibited the highest and lowest NOS activity, respectively. Cell growth was inversely correlated to the amount of NO produced by the cell lines. Conversely, in the avascular rabbit cornea assay, H.end.FB and H80 cells were strongly angiogenic, while H73 were poorly angiogenic, indicating that the ability of the cells to induce neovascularization was associated with the extent of NO produced. Consistently, systemic administration to rabbits of the NOS inhibitor N(w)-nitro-L-arginine methyl ester (L-NAME) significantly reduced the angiogenicity of H.end.FB cells. RT-PCR evidenced that H.end.FB expressed mRNA for TGF-beta1 and all VEGF isoforms, VEGF165 being predominantly expressed. NOS inhibition reduced the basal expression of VEGF isoforms, while it markedly potentiated TGF-beta1 expression. These results indicate that the endogenous production of NO in tumor cells can serve as an autocrine/paracrine signalling mechanism of progression, by controlling angiogenic factor/modulator expressio

Involvement of bradykinin B2 receptor in pathological vascularization in oxygen-induced retinopathy in mice and rabbit cornea

The identification of components of the kallikrein-kinin system in the vitreous from patients with microvascular retinal diseases suggests that bradykinin (BK) signaling may contribute to pathogenesis of retinal vascular complications. BK receptor 2 (B2R) signaling has been implicated in both pro-inflammatory and pro-angiogenic effects promoted by BK. Here, we investigated the role of BK/B2R signaling in the retinal neovascularization in the oxygen-induced retinopathy (OIR) model. Blockade of B2R signaling by the antagonist fasitibant delayed retinal vascularization in mouse pups, indicating that the retinal endothelium is a target of the BK/B2R system. In the rabbit cornea assay, a model of pathological neoangiogenesis, the B2 agonist kallidin induced vessel sprouting and promoted cornea opacity, a sign of edema and tissue inflammation. In agreement with these results, in the OIR model, a blockade of B2R signaling significantly reduced retinal neovascularization, as determined by the area of retinal tufts, and, in the retinal vessel, it also reduced vascular endothelial growth factor and fibroblast growth factor-2 expression. All together, these findings show that B2R blockade reduces retinal neovascularization and inhibits the expression of proangiogenic and pro-inflammatory cytokines, suggesting that targeting B2R signaling may be an effective strategy for treating ischemic retinopathy

Entwicklung einer Methodik zur stichprobengestützten Erfassung und Regionalisierung von Zustandseigenschaften der Waldstandorte

Der Humus- und Nährstoffstatus von Waldböden wird durch Klimawandel, anthropogene Stoffeinträge und Bewirtschaftungsmaßnahmen fortwährend beeinflusst. In Abhängigkeit ihrer bodenphysikalischen und -chemischen Eigenschaften können Waldböden sich verändernde Umweltbedingungen abpuffern oder diese sogar verstärken. Daher müssen die Standortsverhältnisse und deren Entwicklungstendenzen für langfristig angelegte forstliche Entscheidungen berücksichtigt werden. Ziel des Projekts war es, praxistaugliche Indikatoren für waldbaulich/ökologisch relevante Standortszustände zu identifizieren und diese in das Verfahren der Standortserkundung zu integrieren. Hierfür wurden zunächst Humus- und Oberbodendaten aus verschiedenen Erhebungen bezüglich ihrer standörtlichen, räumlichen und zeitlichen Varianz ausgewertet. Nachfolgend sollte ein Methodenvorschlag zur Erfassung der relevanten Standortseigenschaften abgeleitet werden. [...]Climate change and anthropogenic substance load and forest management have a lasting impact on the status of humus and nutrients in forest soils. However, forest soils can buffer or even enhance changes of environmental conditions. Therefore, site conditions and their development have to be considered for long-term forest management decisions. The project aimed at identifying practicable indicators of relevant ecological and silvicultural site conditions that can be integrated into Site Survey of forest soils. A further objective was to develop a methods proposal for the inventory of relevant site conditions. Data of organic layer and topsoil from different inventories was evaluated regarding the site-specific, spatial and temporal variance. [...

Vimentin expression influences flow dependent VASP phosphorylation and regulates cell migration and proliferation

The cytoskeleton plays a central role for the integration of biochemical and biomechanical signals across the cell required for complex cellular functions. Recent studies indicate that the intermediate filament vimentin is necessary for endothelial cell morphogenesis e.g. in the context of leukocyte transmigration. Here, we present evidence, that the scaffold provided by vimentin is essential for VASP localization and PKG mediated VASP phosphorylation and thus controls endothelial cell migration and proliferation. Vimentin suppression using siRNA technique significantly decreased migration velocity by 50% (videomicroscopy), diminished transmigration activity by 42.5% (Boyden chamber) and reduced proliferation by 43% (BrdU-incorporation). In confocal microscopy Vimentin colocalized with VASP and PKG in endothelial cells. Vimentin suppression was accompanied with a translocation of VASP from focal contacts to the perinuclear region. VASP/Vimentin and PKG/Vimentin colocalization appeared to be essential for proper PKG mediated VASP phosphorylation because we detected a diminished expression of PKG and p(Ser239)-VASP in vimentin-suppressed cells, Furthermore, the induction of VASP phosphorylation in perfused arteries was markedly decreased in vimentin knockout mice compared to wildtypes. A link is proposed between vimentin, VASP phosphorylation and actin dynamics that delivers an explanation for the important role of vimentin in controlling endothelial cell morphogenesis

Divergent effects of quercetin conjugates on angiogenesis

The present study reports the activities of quercetin and its main circulating conjugates in man (quercetin-3′-sulphate (Q3′S) and quercetin-3-glucuronide (Q3G)) on in vivo angiogenesis induced by vascular endothelial growth factor (VEGF) and examines the effects of these molecules on cultured endothelial cells. We found opposing effects of quercetin and its metabolites on angiogenesis. While quercetin and Q3G inhibited VEGF-induced endothelial cell functions and angiogenesis, Q3′S per se promoted endothelial cell proliferation and angiogenesis. The inhibitory effect elicited by Q3G was linked to inhibition of extracellular signal-regulated kinases 1/2 (ERK1/2) phosphorylation elicited by VEGF. The activation of endothelial cells by Q3′S was associated to stimulation of VEGF receptor-2 and to downstream signalling activation (phosphatidylinositol-3 kinase/Akt and nitric oxide synthase pathways), ultimately responsible for ERK1/2 phosphorylation. These data indicate that the effects of circulating quercetin conjugates on angiogenesis are different depending on the nature of the conjugate. Q3G andQ3′S are the two major conjugates in plasma, but their ratio is dependenton several factors, so thatinhibition or activation of angiogenesis could be subtly shifted as a result of metabolismin viv

Inhibition of cell cycle progression by the hydroxytyrosol-cetuximab combination yields enhanced chemotherapeutic efficacy in colon cancer cells

Hydroxytyrosol (HT), a polyphenol of olive oil, downregulates epidermal growth factor (EGFR) expression and inhibits cell proliferation in colon cancer (CC) cells, with mechanisms similar to that activated by the EGFR inhibitor, cetuximab. Here, we studied whether HT treatment would enhance the cetuximab inhibitory effects on cell growth in CC cells. HT-cetuximab combination showed greater efficacy in reducing cell growth in HT- 29 and WiDr cells at concentrations 10 times lower than when used as single agents. This reduction was clearly linked to cell cycle blockade, occurring at G2/M phase. The cell cycle arrest in response to combination treatment is related to cyclins B, D1, and E, and cyclin-dependent kinase (CDK) 2, CDK4, and CDK6 down-regulation, and to the concomitant over-expression of CDK inhibitors p21 and p27. HT and cetuximab stimulated a caspase-independent cell death cascade, promotedtranslocation of apoptosis-inducing factor (AIF) from mitochondria to nucleus and activated the autophagy process. Notably, normal colon cells and keratinocytes were less susceptible to comboinduced cell death and EGFR downregulation. These results suggest a potential role of diet, containing olive oil, during cetuximab chemotherapy of colon tumor. HT may be a competent therapeutic agent in CC enhancing the effects of EGFR inhibitors

Cu(II) and Zn(II) complexes with hyaluronic acid and its sulphated derivative.Effect on the motility of vascular endothelial cells.

With the aim of improving the compatibility of biomaterials to be used for the construction of cardiovascular prosthesis, we have designed bioactive macromolecules resulting from chemical modifications of hyaluronic acid (Hyal). The stability constants of Cu(II) and Zn(II) complexes with the sulphated derivative of hyaluronic acid (HyalS3.5) were evaluated. Two different complexes have been found for each metal ion, CuL, Cu(OH)2L and ZnL, Zn(OH)2L (L means the disaccharide unit of the ligands) in aqueous solution at 37 degrees C. The dihydroxo Cu(II) complex was present in high percentage at pH=7.4. On the contrary, the Zn(II) ion was present with a relatively low percentage of both complexes. The ability to stimulate endothelial cell adhesion and migration was evaluated for Hyal, HyalS3.5 and their complexes with Cu(II) and Zn(II) ions. The results revealed that Hyal and [Cu(OH)2HyalS3.5](4.5)- induced cell adhesion, while [ZnHyalS3.5](2.5)- and [Zn(OH)2HyalS3.5](4.5)- inhibited the process. The chemotactic activity of increasing concentrations of the above complexes was also evaluated, demonstrating that [Cu(OH)2HyalS3.5](4.5)- complex at 1 microM concentration was the most active in inducing cell migration. These results have been also strengthened by analysing adherent cell migration in agarose. In conclusion, sulphated hyaluronic acid coordinated to Cu(II) seems to be a promising matrix molecule for the construction of cardiovascular prosthesis.