A wild Marsh Warbler?×?Sedge Warbler hybrid (Acrocephalus palustris?×?A. schoenobaenus) in Norway documented with molecular markers

We present photographic and molecular evidence of a wild Marsh Warbler × Sedge Warbler (Acrocephalus palustris × A. schoenobaenus) hybrid that occurred over three breeding seasons (2007–2009) near Trondheim, Central Norway. The bird had the appearance of a Marsh Warbler but with some typical Sedge Warbler plumage traits. DNA analyses of a few plucked body feathers, using the COI barcode region (mtDNA) and conserved microsatellite loci, confirmed that the bird was a hybrid, with a Marsh Warbler mother and a Sedge Warbler father.     

Novel hydrophobic standards for membrane protein molecular weight determinations via sodium dodecyl sulfate-polyacrylamide gel electrophoresis

Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) is a universally employed technique that separates proteins on the basis of molecular weight (MW). However, membrane proteins are known to size anomalously on SDS-PAGE calibrated with conventional standards, an issue that complicates interpretation of protein identity, purity, degradation, and/or stoichiometry. Here we describe the preparation of novel polyleucine hydrophobic standards for SDS-PAGE that reduce the average deviation of the apparent MW from the formula MW of natural membrane proteins to 7% versus 20% with commercially available standards. Our results suggest that gel calibration with hydrophobic standards may facilitate the interpretation of membrane protein SDS-PAGE experiments.     

Role of disturbed vegetation in mapping the boreal zone in northern Eurasia

Question: Is there a need for disturbance mapping integrated in the CircumBoreal Vegetation Mapping Program? Location: Eurasian boreal forest. Disturbance and mapping: The boreal zone is characterized by a multitude of natural and anthropogenic disturbance agents with importance over a wide range of spatial and temporal scales. Disturbance is a prime driver of succession in most of the boreal zone, producing landscape diversity characterized by a large‐scale vegetation mosaic of early to late succession states. When mapping the circumboreal vegetation, spatial extent, time involved from disturbance to recovered condition and likelihood of interacting disturbance types are crucial for how current vegetation is interpreted and subsequently included as map characteristics. In this paper we present examples from the boreal zone where natural and/or anthropogenic disturbance regimes dominate the state and distribution of vegetation, and possibilities for assessing the nature and extent of the disturbed regions using remotely sensed data. Conclusion: Disturbed vegetation occupies large areas in the boreal zone and related vegetation successions should be adequately represented when mapping the zone. In regions where the ‘potential natural vegetation’ is a hypothetical reconstruction from remnants of ‘natural’ vegetation it would be preferable to use the concept of ‘actual real vegetation’ for which remote sensing at coarse, medium and fine resolution is an efficient tool. The Land Cover Classification System (LCCS) may offer sufficient flexibility to incorporate information about the disturbance of circumboreal vegetation.     

Phosphorylation of the Na,K-ATPase and the H,K-ATPase

Phosphorylation is a widely used, reversible means of regulating enzymatic activity. Among the important phosphorylation targets are the Na⁺,K⁺- and H⁺,K⁺-ATPases that pump ions against their chemical gradients to uphold ionic concentration differences over the plasma membrane. The two pumps are very homologous, and at least one of the phosphorylation sites is conserved, namely a cAMP activated protein kinase (PKA) site, which is important for regulating pumping activity, either by changing the cellular distribution of the ATPases or by directly altering the kinetic properties as supported by electrophysiological results presented here. We further review the other proposed pump phosphorylations.     

The development of new algorithms for remote sensing of snow conditions based on data from the catchment of Øvre Heimdalsvatn and the vicinity

The catchment of Øvre Heimdalsvatn and the surrounding area was established as a site for snow remote sensing algorithm development, calibration and validation in 1997. Information on snow cover and snowmelt are important for understanding the timing and scale of many lake ecosystem processes. Field campaigns combined with data from airborne sensors and spaceborne high-resolution sensors have been used as reference data in experiments over many years. Several satellite sensors have been utilised in the development of new algorithms, including Terra MODIS and Envisat ASAR. The experiments have been motivated by operational prospects for snow hydrology, meteorology and climate monitoring by satellite-based remote sensing techniques. This has resulted in new time-series multi-sensor approaches for monitoring of snow cover area (SCA) and snow surface wetness (SSW). The idea was to analyse, on a daily basis, a time series of optical and radar satellite data in multi-sensor models. The SCA algorithm analyses each optical and synthetic aperture radar (SAR) image individually and combines them into a day product based on a set of confidence functions. The SSW algorithm combines information about the development of the snow surface temperature and the snow grain size (SGS) in a time-series analysis. The snow cover algorithm is being evaluated for application in a global climate monitoring system for snow variables. The successful development of these algorithms has led to operational applications of snow monitoring in Norway and Sweden, as well as enabling the prediction of the spring snowmelt flood and thus the initiation of many lake production processes.     

Altered fibroblast proteoglycan production in COPD

Background

Airway remodeling in COPD includes reorganization of the extracellular matrix. Proteoglycans play a crucial role in this process as regulators of the integrity of the extracellular matrix. Altered proteoglycan immunostaining has been demonstrated in COPD lungs and this has been suggested to contribute to the pathogenesis. The major cell type responsible for production and maintenance of ECM constituents, such as proteoglycans, are fibroblasts. Interestingly, it has been proposed that central airways and alveolar lung parenchyma contain distinct fibroblast populations. This study explores the hypothesis that altered depositions of proteoglycans in COPD lungs, and in particular versican and perlecan, is a result of dysregulated fibroblast proteoglycan production.

Methods

Proliferation, proteoglycan production and the response to TGF-β₁ were examined in vitro in centrally and distally derived fibroblasts isolated from COPD patients (GOLD stage IV) and from control subjects.

Results

Phenotypically different fibroblast populations were identified in central airways and in the lung parenchyma. Versican production was higher in distal fibroblasts from COPD patients than from control subjects (p < 0.01). In addition, perlecan production was lower in centrally derived fibroblasts from COPD patients than from control subjects (p < 0.01). TGF-β₁ triggered similar increases in proteoglycan production in distally derived fibroblasts from COPD patients and control subjects. In contrast, centrally derived fibroblasts from COPD patients were less responsive to TGF-β₁ than those from control subjects.

Conclusions

The results show that fibroblasts from COPD patients have alterations in proteoglycan production that may contribute to disease development. Distally derived fibroblasts from COPD patients have enhanced production of versican that may have a negative influence on the elastic recoil. In addition, a lower perlecan production in centrally derived fibroblasts from COPD patients may indicate alterations in bronchial basement membrane integrity in severe COPD.     

Circulating surfactant protein -D is low and correlates negatively with systemic inflammation in early, untreated rheumatoid arthritis

Introduction

Surfactant protein D (SP-D) is a collectin with immuno-regulatory functions, which may depend on oligomerization. Anti-microbial and anti-inflammatory properties have been attributed to multimeric SP-D variants, while trimeric subunits per se have been suggested to enhance inflammation. Previously, we reported low circulating SP-D in early rheumatoid arthritis (RA), and the present investigation aims to extend these data by serial SP-D serum measurements, studies on synovial fluid, SP-D size distribution and genotyping in patients with early RA.

Methods

One-hundred-and-sixty disease-modifying antirheumatic drug (DMARD) naïve RA patients with disease duration less than six months were studied prospectively for four years (CIMESTRA (Ciclosporine, Methotrexate, Steroid in RA) trial) including disease activity measures (C-reactive protein, joint counts and Health Assessment Questionnaire (HAQ) score), autoantibodies, x-ray findings and SP-D. SP-D was quantified by enzyme-linked immunosorbent assay (ELISA) and molecular size distribution was assessed by gel filtration chromatography. Further, SP-D Met11Thr single nucleotide polymorphism (SNP) analysis was performed.

Results

Serum SP-D was significantly lower in RA patients at baseline compared with healthy controls (P < 0.001). SP-D increased slightly during follow-up (P < 0.001), but was still subnormal at four years after adjustment for confounders (P < 0.001). SP-D in synovial fluid was up to 2.5-fold lower than in serum. While multimeric variants were detected in serum, SP-D in synovial fluid comprised trimeric subunits only. There were no significant associations between genotype distribution and SP-D. Baseline SP-D was inversely associated to CRP and HAQ score. A similar relationship was observed regarding temporal changes in SP-D and CRP (zero to four years). SP-D was not associated to x-ray findings.

Conclusions

This study confirms that circulating SP-D is persistently subnormal in early and untreated RA despite a favourable therapeutic response obtained during four years of follow-up. SP-D correlated negatively to disease activity measures, but was not correlated with x-ray progression or SP-D genotype. These observations suggest that SP-D is implicated in RA pathogenesis at the protein level. The exclusive presence of trimeric SP-D in affected joints may contribute to the maintenance of joint inflammation.

Trial registration

(j.nr NCT00209859).     

Intracellular Targeting Signals and Lipid Specificity Determinants of the ALA/ALIS P4-ATPase Complex Reside in the Catalytic ALA α-Subunit

Members of the P₄ subfamily of P-type ATPases are believed to catalyze flipping of phospholipids across cellular membranes, in this way contributing to vesicle biogenesis in the secretory and endocytic pathways. P₄-ATPases form heteromeric complexes with Cdc50-like proteins, and it has been suggested that these act as β-subunits in the P₄-ATPase transport machinery. In this work, we investigated the role of Cdc50-like β-subunits of P₄-ATPases for targeting and function of P₄-ATPase catalytic α-subunits. We show that the Arabidopsis P₄-ATPases ALA2 and ALA3 gain functionality when coexpressed with any of three different ALIS Cdc50-like β-subunits. However, the final cellular destination of P₄-ATPases as well as their lipid substrate specificity are independent of the nature of the ALIS β-subunit they were allowed to interact with.     

22-Hydroxycholesterols regulate lipid metabolism differently than T0901317 in human myotubes

The nuclear liver X receptors (LXRalpha and beta) are regulators of lipid and cholesterol metabolism. Oxysterols are known LXR ligands, but the functional role of hydroxycholesterols is at present unknown. In human myotubes, chronic exposure to the LXR ligand T0901317 promoted formation of diacylglycerol (DAG) and triacylglycerol (TAG), 22-R-hydroxycholesterol (22-R-HC) had no effect, and 22-S-hydroxycholesterol (22-S-HC) reduced the formation. In accordance with this, 22-HC and T0901317 regulated the expression of fatty acid transporter CD36, stearoyl-CoA desaturase-1, acyl-CoA synthetase long chain family member 1 and fatty acid synthase (FAS) differently; all genes were increased by T0901317, 22-R-HC did not change their expression level, while 22-S-HC reduced it. Transfection studies confirmed that the FAS promoter was activated by T0901317 and repressed by 22-S-HC through an LXR response element in the promoter. Both 22-R-HC and T0901317 increased gene expression of LXRalpha, sterol regulatory element-binding protein 1c and ATP-binding cassette transporter A1, while 22-S-HC had little effect. In summary, 22-R-HC regulated lipid metabolism and mRNA expression of some LXR target genes in human myotubes differently than T0901317. Moreover, 22-S-HC did not behave like an inactive ligand; it reduced synthesis of complex lipids and repressed certain genes involved in lipogenesis and lipid handling.     

Evidence for a two-step mechanism involved in the formation of covalent HC x TSG-6 complexes

IalphaI and TSG-6 interact to form a covalent bond between the C-terminal Asp alpha-carbon of an IalphaI heavy chain (HC) and an unknown component of TSG-6. This event disrupts the protein-glycosaminoglycan-protein (PGP) cross-link and dissociates IalphaI. In simple terms the interaction involves 5 components: (i) the IalphaI HCs, (ii) bikunin, (iii) chondroitin sulfate chain, (iv) TSG-6, and (v) divalent cations. To understand the molecular mechanism of complex formation, the effect of these were separately examined. The data show that although the mature covalent cross-link between the HCs and TSG-6 only involves the C-terminal Asp residue, the native fold of both IalphaI and TSG-6 was essential for the reaction to occur. Similarly, complex formation was prevented if the chondroitin sulfate chain was cleaved, releasing bikunin but maintaining the HC1 and HC2 PGP cross-links. In contrast, releasing the majority of the bikunin protein moiety by limited proteolysis did not prevent complex formation. An analysis of the divalent-cation requirements revealed two distinct interactions between IalphaI and TSG-6: (i) a noncovalent manganese, magnesium, or calcium-independent interaction between TSG-6 and the chondroitin sulfate chain (Kd 180 nM) and (ii) a covalent manganese, magnesium, or calcium-dependent interaction generating HC1 x TSG-6, HC2 x TSG-6, and high molecular weight (HMW) IalphaI. Significantly, both free TSG-6 and HC x TSG-6 complexes were able to bind the chondroitin sulfate chain suggesting that the sites on TSG-6 were distinct. On the basis of these findings, we propose a two-step reaction mechanism involving two putative binding sites. Initially, a cation-independent interaction between TSG-6 and the chondroitin sulfate chain is formed at site 1. Subsequently, a cation-dependent transesterification occurs, generating the covalent HC x TSG-6 cross-link at another site, site 2.