Two centuries of vegetation succession in an inland sand dune area,central Netherlands

Questions: (a) What are the rates and directions of vegetation succession in an inland sand‐dune system? (b) What are the differences in successional trajectories in different relief types? and (c) Is it possible to preserve the last areas of still active dunes and under what circumstances? Location: The study sites were located in the northern part of the Veluwe Region, central Netherlands; longitude 5°44′ E, latitude 52°20′ N, altitude 9 to 24 m a.s.l. Methods: Vegetation and relief mapping was conducted in three permanent plots, 200 m × 200 m in size, in 1988 and 2003. Phytosociological relevés (2400) were recorded in each 10 m × 10 m subplots. Age of woody species was determined by wood coring. Geographic Information System, ordination analyses, and TWINSPAN were used for data exploration and elaboration. Results: A total of 70 vascular plants and 19 bryophytes were recorded over successional stages spanning approximately190 years. The following dominant species formed the sequence of successional stages, but not all participated in all relief types: Ammophila arenaria, Festuca arenaria, Corynephorus canescens, Festuca ovina and Agrostis capillaris, and pine forest dominated in its herb layer at first by Deschampsia flexuosa and later by either Empetrum nigrum, Vaccinium myrtillus or Vaccinium vitis‐idaea. Conclusions: The successional trajectory is basically unidirectional for more than 100 years; no clear multiple successional pathways were observed, as is frequent in coastal dunes. Successional divergence was observed after approximately 130 years in the composition of the herb layer in the closed pine forest. The obvious vegetation heterogeneity in the still active sand‐blown area is related to differences in timing of vegetation establishment on particular relief types, thus the succession exhibits a terrain‐dependent asynchronous character. We conclude that the last patches of still‐active sand dunes can be preserved only by repeated strong artificial disturbances.     

Rhamnolipid-producing thermophilic bacteria of species <Emphasis Type="Italic">Thermus</Emphasis> and <Emphasis Type="Italic">Meiothermus</Emphasis>

Novel rhamnolipid-producing strains of three thermophilic bacteria, Thermus sp., T. aquaticus and Meiothermus ruber were identified that have not been previously described as rhamnolipid producers. Rhamnolipids were extracted from supernatant and further purified by thin-layer chromatography. Mass spectrometry with negative electrospray ionization revealed 77 rhamnolipid homologues varying in chain length and unsaturation. Tandem mass spectrometry identified mono-rhamnolipid and di-rhamnolipid homologues containing one or two 3-hydroxy-fatty acids, saturated, monounsaturated or diunsaturated, even- or odd-chain, up to unusual long chains with 24 carbon atoms. The stereochemistry of rhamnose was L and that of 3-hydroxy-fatty acids was R, the position of double bonds in monoenoic acids was cis ω-9. All three strains produced a rhamnolipid that differs in structure from Pseudomonas aeruginosa rhamnolipids and exhibits excellent surfactant properties. Importantly, in comparison to P. aeruginosa both strains, i.e., Thermus and Meiothermus, are Biosafety level 1 microorganisms and are not pathogenic to humans.     

Coiled coil peptides as universal linkers for the attachment of recombinant proteins to polymer therapeutics

We have designed, synthesized, and characterized peptides containing four repeats of the sequences VAALEKE (peptide E) or VAALKEK (peptide K). While the peptides alone adopt in aqueous solutions a random coil conformation, their equimolar mixture forms heterodimeric coiled coils as confirmed by CD spectroscopy. 5-Azidopentanoic acid was connected to the N-terminus of peptide E via a short poly(ethylene glycol) spacer. The terminal azide group enabled conjugation of the peptide with a synthetic drug carrier based on the N-(2-hydroxypropyl)methacrylamide copolymer containing propargyl groups using "click" chemistry. When incorporated into the polymer drug carrier, peptide E formed a stable noncovalent complex with peptide K belonging to a recombinant single-chain fragment (scFv) of the M75 antibody. The complex thereby mediates a noncovalent linkage between the polymer drug carrier and the protein. The recombinant scFv antibody fragment was selected as a targeting ligand against carbonic anhydrase IX-a marker overexpressed by tumor cells of various human carcinomas. The antigen binding affinity of the polymer-scFv complex was confirmed by ELISA. This approach offers a well-defined, specific, and nondestructive universal method for the preparation of protein (antibody)-targeted polymer drug and gene carriers designed for cell-specific delivery.     

Laminar analysis of excitatory local circuits in vibrissal motor and sensory cortical areas

Rodents move their whiskers to locate and identify objects. Cortical areas involved in vibrissal somatosensation and sensorimotor integration include the vibrissal area of the primary motor cortex (vM1), primary somatosensory cortex (vS1; barrel cortex), and secondary somatosensory cortex (S2). We mapped local excitatory pathways in each area across all cortical layers using glutamate uncaging and laser scanning photostimulation. We analyzed these maps to derive laminar connectivity matrices describing the average strengths of pathways between individual neurons in different layers and between entire cortical layers. In vM1, the strongest projection was L2/3→L5. In vS1, strong projections were L2/3→L5 and L4→L3. L6 input and output were weak in both areas. In S2, L2/3→L5 exceeded the strength of the ascending L4→L3 projection, and local input to L6 was prominent. The most conserved pathways were L2/3→L5, and the most variable were L4→L2/3 and pathways involving L6. Local excitatory circuits in different cortical areas are organized around a prominent descending pathway from L2/3→L5, suggesting that sensory cortices are elaborations on a basic motor cortex-like plan.     

Perceive, Co-opt, Modify, and Live! Organism as a Centre of Experience

Organic appearances are largely neglected by contemporary biology; partly because they are regarded as superficial effects of causes concealed beneath the surface. The persuasion that everything what does exist is existent for some immediately non-apparent reasons belongs to a general belief of modern science. All organisms are of the same evolutionary origin and of the same world wherein appearance coincides with existence. In this study, living beings are approached as appearing centers of experience that reflects their evolutionary history. From biohermeneutic point of view the evolution of organisms, interactions between organisms, and their relationships to environment is understood as “evolution of interpretations”. I use simple conceptual framework of perception, semiotic co-option, and modification to explain the evolution of semantic organs, i.e. organs that operate through the meaning that was given to them by an animal interpreter.     

Pharmacologic modulation of serine/threonine phosphorylation highly sensitizes PHEO in a MPC cell and mouse model to conventional chemotherapy

Background

The failure of cytotoxic cancer regimens to cure the most drug-resistant, well-differentiated solid tumors has been attributed to the heterogeneity of cell types that differ in their capacities for growth, differentiation, and metastases. We investigated the effect of LB1, a small molecule inhibitor of serine/threonine protein phosphatase 2A (PP2A), on its ability to inhibit a low growth fraction and highly drug-resistant solid neuroendocrine tumor, such as metastatic pheochromocytoma (PHEO). Subsequently, we evaluated the increased efficacy of chemotherapy combined with LB1.

Methodology/Principal Findings

The effect of LB1 and temozolomide (TMZ), a standard chemotherapeutic agent that alone only transiently suppressed the growth and regression of metastatic PHEO, was evaluated in vitro on a single PHEO cell line and in vivo on mouse model of metastatic PHEO. In the present study, we show that metastatic PHEO, for which there is currently no cure, can be eliminated by combining LB1, thereby inhibiting PP2A, with TMZ. This new treatment approach resulted in long term, disease-free survival of up to 40% of animals bearing multiple intrahepatic metastases, a disease state that the majority of patients die from. Inhibition of PP2A was associated with prevention of G1/S phase arrest by p53 and of mitotic arrest mediated by polo-like kinase 1 (Plk-1).

Conclusions/Significance

The elimination of DNA damage-induced defense mechanisms, through transient pharmacologic inhibition of PP2A, is proposed as a new approach for enhancing the efficacy of non-specific cancer chemotherapy regimens against a broad spectrum of low growth fraction tumors very commonly resistant to cytotoxic drugs.     

Soil nutrient heterogeneity and competitive ability of three grass species (<Emphasis Type="Italic">Festuca ovina,Arrhenatherum elatius</Emphasis> and <Emphasis Type="Italic">Calamagrostis epigejos</Emphasis>) in experimental conditions

We studied the effects of differences in root growth and nutrient pool on the competitive ability of Festuca ovina (short grass), Arrhenatherum elatius and Calamagrostis epigejos (tall grasses) grown in monocultures and in mixtures of homogeneous and heterogeneous environments during two growing seasons. Analysis of variance revealed a significant effect of plant species on nutrient concentrations in above-ground biomass and of substrate type on contents of N, K, Ca, Mg in biomass. The ANOVA also confirmed the significant effect of competitive environment on the concentration of N, K in above-ground biomass. In heterogeneous environments, both tall grasses (in competition with F. ovina) were able to produce more roots in the nutrient-rich patches and to accumulate more nitrogen in plant tissues, which was associated with higher yield of their above-ground biomass. Thus, the relative competitive ability for nutrients of both tall grasses was higher than that of F. ovina. This competitive ability of A. elatius to C. epigejos increased in heterogeneous treatments.     

Growth/differentiation factor-15 inhibits differentiation into osteoclasts—A novel factor involved in control of osteoclast differentiation

Survival and capability of cancer cells to form metastases fundamentally depend on interactions with their microenvironment. Secondary tumors originating from prostate carcinomas affect remodeling of bone tissue and can induce both osteolytic and osteocondensing lesions. However, particular molecular mechanisms responsible for selective homing and activity of cancer cells in bone microenvironment have not been clarified yet. Growth/differentiation factor-15 (GDF-15), a distant member of the TGF-β protein family, has recently been associated with many human cancers, including prostate.     

Fungal nitrilases as biocatalysts: Recent developments

Of the numerous putative fungal nitrilases available from protein databases only a few enzymes were purified and characterized. The purified nitrilases from Fusarium solani, Fusarium oxysporum f. sp. melonis and Aspergillus niger share a preference for (hetero)aromatic nitriles, temperature optima between 40 and 50 °C and pH optima in the slightly alkaline region. On the other hand, they differ in their chemoselectivity, i.e. their tendency to produce amides as by-products. The production of fungal nitrilases is increased by up to three orders of magnitude on the addition of 2-cyanopyridine to the culture media. The whole-cell and subcellular biocatalysts were immobilized by various methods (LentiKats®; adsorption on hydrophobic or ion exchange resins; cross-linked enzyme aggregates). Operational stability was examined using continuous stirred membrane bioreactors. Fungal nitrilases appear promising for biocatalytic applications and biodegradation of nitrile environmental contaminants.