Peltidiphonte gen. n., a New Taxon of Laophontidae (Copepoda: Harpacticoida) from Coral Substrates of the Indo-West Pacific Ocean

A new genus of the harpacticoid family Laophontidae is described and named Peltidiphonte gen. n. Eight new species are assigned to this genus; they were collected from different locations in the Indo-West Pacific Ocean, including the Comoros, the Kenyan coast, the Red Sea, the Andaman Islands, the northern coast of Papua New Guinea, the Solomon Islands and the northeastern coast of Australia. Most of the specimens were collected from dead coral substrates, suggesting a close affinity between the members of the new genus and this substrate. Peltidiphonte gen. n. can easily be discriminated from other genera of the family by the extremely depressed body and by the shape of the antennule, bearing two (or three) processes on the first segment and a hook-like process along the outer margin of the second segment. An identification key for the new genus is provided.     

Dendritic cells in the recognition of intestinal microbiota

Mucosal dendritic cells (DCs) constantly survey the luminal microenvironment which contains commensal microbiota and potentially harmful organisms regulating pathogen recognition and adaptive as well as innate defense activation. Distinct mechanisms are beginning to emerge by which intestinal antigen sampling and handling is achieved ensuring specificity and contributing to redundancy in pathogen detection. Distinct DC subsets are associated with these mechanisms and regulate specific innate or adaptive immune responses to help distinguish between commensal microbiota, pathogens and self antigens. Understanding DC biology in the mucosal immune system may contribute to the unraveling of infection routes of intestinal pathogens and may aid in developing novel vaccines and therapeutic strategies for the treatment of infectious and inflammatory diseases.     

Phytoremediation of selenium using subsurface-flow constructed wetland

The potential of two plant species, Phragmites australis (common reed) and Typha latifolia (cattail), in the phytoremediation process of selenium (Se) was studied in subsurface-flow constructed wetland (SSF). Se was supplemented continuously at a concentration of 100 microg Se L(-1) in the inlet of the cultivation beds of the SSF. Water samples collected from the outlet of the Phragmites bed after 1, 3, 6, 9, and 12 wk of treatments showed that Se content was under detectable limits. Water samples collected from the Typha bed at the same five periods showed that Se concentrations in the outlet were 55, 47, 65, 76, and 25 microg/L, respectively. The results of bioaccumulation in the biomass of both species after 12 wk of treatment indicated that Typha plants accumulated Se mainly in fine roots. Phragmites accumulated Se mainly in leaves and rhizomes, and moderate levels were found in stems and fine organic materials. The results indicate that common reed is a very good species for Se phytoextraction and phytostabilization (immobilization) and that cattail is only a phytostabilization species. The use of common reed and cattail for Se phytoremediation in a SSF system and in constructed wetland models are discussed.     

(3)H]-M-MPEP, a potent, subtype-selective radioligand for the metabotropic glutamate receptor subtype 5

The synthesis of a new potent, subtype-selective radioligand [(3)H]-M-MPEP (2-methyl-6-((3-methoxyphenyl)ethynyl)-pyridine) and its in vitro pharmacological characteristics are described. Science Ltd.     

On the potential of fatty acids as trophic markers in Arctic grazers: feeding experiments with sea urchins and amphipods fed nine diets of macroalgae

To elucidate dietary preferences of benthic grazers at the Arctic Kongsfjorden by means of fatty acid trophic markers, ten different parallel treatments (starvation, 3 species of red macroalgae, 4 species of brown macroalgae and 2 species of green macroalgae) were offered as mono-algal diet to specimens of the dominant sea urchin Strongylocentrotus droebachiensis (Echinodermata, Echinoidea) and the gammarid amphipod Gammarellus homari (Crustacea, Amphipoda). At the end of the 3-week feeding experiments, amphipods and sea urchins (soft tissue) were deep-frozen and analysed for total lipid contents as well as fatty acid (FA) compositions. In addition, FA profiles of the algal species were determined and screened for specific FA patterns or single FAs qualifying as potential trophic markers in the grazers. Despite their diets of nine algal species with different FA compositions, FA patterns of the sea urchins and amphipods revealed a pronounced similarity between treatments. This strong similarity was also observed in the faecal pellets of the sea urchins. Hence, deviating FA compositions of the macroalgae were neither reflected in the FA patterns of the grazers’ tissue nor in their faecal pellets. Suitable algal FA trophic markers could thus not be identified in the two grazers from Kongsfjorden. The rather low lipid levels, especially in the amphipods, as well as a pronounced degradation and modification of FAs may explain that the FA trophic marker approach did not provide evidence of dietary preferences. Future experiments may obtain a higher resolution of potential FA trophic markers by analysing separate lipid classes or single tissues of lipid-poor grazers. Alternatively, different methods are needed to reveal high-resolution trophic relationships between macroalgae and herbivores in Kongsfjorden.     

Ghrelin modulates baroreflex-regulation of sympathetic vasomotor tone in healthy humans

Ghrelin, a neuropeptide originally known for its growth hormone-releasing and orexigenic properties, exerts important pleiotropic effects on the cardiovascular system. Growing evidence suggests that these effects are mediated by the sympathetic nervous system. The present study aimed at elucidating the acute effect of ghrelin on sympathetic outflow to the muscle vascular bed (muscle sympathetic nerve activity, MSNA) and on baroreflex-mediated arterial blood pressure (BP) regulation in healthy humans. In a randomized double-blind cross-over design, 12 lean young men were treated with a single dose of either ghrelin 2 μg/kg iv or placebo (isotonic saline). MSNA, heart rate (HR), and BP were recorded continuously from 30 min before until 90 min after substance administration. Sensitivity of arterial baroreflex was repeatedly tested by injection of vasoactive substances based on the modified Oxford protocol. Early, i.e., during the initial 30 min after ghrelin injection, BP significantly decreased together with a transient increase of MSNA and HR. In the course of the experiment (>30 min), BP approached placebo level, while MSNA and HR were significantly lower compared with placebo. The sensitivity of vascular arterial baroreflex significantly increased at 30-60 min after intravenous ghrelin compared with placebo, while HR response to vasoactive drugs was unaltered. Our findings suggest two distinct phases of ghrelin action: In the immediate phase, BP is decreased presumably due to its vasodilating effects, which trigger baroreflex-mediated counter-regulation with increases of HR and MSNA. In the delayed phase, central nervous sympathetic activity is suppressed, accompanied by an increase of baroreflex sensitivity.     

Diversity of methyl halide-degrading microorganisms in oceanic and coastal waters

Methyl halides have a significant impact on atmospheric chemistry, particularly in the degradation of stratospheric ozone. Bacteria are known to contribute to the degradation of methyl halides in the oceans and marine bacteria capable of using methyl bromide and methyl chloride as sole carbon and energy source have been isolated. A genetic marker for microbial degradation of methyl bromide ( cmuA ) was used to examine the distribution and diversity of these organisms in the marine environment. Three novel marine clades of cmuA were identified in unamended seawater and in marine enrichment cultures degrading methyl halides. Two of these cmuA clades are not represented in extant bacteria, demonstrating the utility of this molecular marker in identifying uncultivated marine methyl halide-degrading bacteria. The detection of populations of marine bacteria containing cmuA genes suggests that marine bacteria employing the CmuA enzyme contribute to methyl halide cycling in the ocean.     

Qualitative and quantitative late blight resistance in the potato cultivar Sarpo Mira is determined by the perception of five distinct RXLR effectors

Potato defends against Phytophthora infestans infection by resistance (R)-gene-based qualitative resistance as well as a quantitative field resistance. R genes are renowned to be rapidly overcome by this oomycete, and potato cultivars with a decent and durable resistance to current P. infestans populations are hardly available. However, potato cultivar Sarpo Mira has retained resistance in the field over several years. We dissected the resistance of 'Sarpo Mira' in a segregating population by matching the responses to P. infestans RXLR effectors with race-specific resistance to differential strains. The resistance is based on the combination of four pyramided qualitative R genes and a quantitative R gene that was associated with field resistance. The qualitative R genes include R3a, R3b, R4, and the newly identified Rpi-Smira1. The qualitative resistances matched responses to avirulence (AVR)3a, AVR3b, AVR4, and AVRSmira1 RXLR effectors and were overcome by particular P. infestans strains. The quantitative resistance was determined to be conferred by a novel gene, Rpi-Smira2. It was only detected under field conditions and was associated with responses to the RXLR effector AvrSmira2. We foresee that effector-based resistance breeding will facilitate selecting and combining qualitative and quantitative resistances that may lead to a more durable resistance to late blight.     

The Tat System for Membrane Translocation of Folded Proteins Recruits the Membrane-stabilizing Psp Machinery in Escherichia coli

Tat systems transport folded proteins across energized membranes of bacteria, archaea, and plant plastids. In Escherichia coli, TatBC complexes recognize the transported proteins, and TatA complexes are recruited to facilitate transport. We achieved an abstraction of TatA from membranes without use of detergents and observed a co-purification of PspA, a membrane-stress response protein. The N-terminal transmembrane domain of TatA was required for the interaction. Electron microscopy displayed TatA complexes in direct contact with PspA. PspB and PspC were important for the TatA-PspA contact. The activator protein PspF was not involved in the PspA-TatA interaction, demonstrating that basal levels of PspA already interact with TatA. Elevated TatA levels caused membrane stress that induced a strictly PspBC- and PspF-dependent up-regulation of PspA. TatA complexes were found to destabilize membranes under these conditions. At native TatA levels, PspA deficiency clearly affected anaerobic TMAO respiratory growth, suggesting that energetic costs for transport of large Tat substrates such as TMAO reductase can become growth limiting in the absence of PspA. The physiological role of PspA recruitment to TatA may therefore be the control of membrane stress at active translocons.     

Dual color photoactivation localization microscopy of cardiomyopathy-associated desmin mutants

Mutations in the DES gene coding for the intermediate filament protein desmin may cause skeletal and cardiac myopathies, which are frequently characterized by cytoplasmic aggregates of desmin and associated proteins at the cellular level. By atomic force microscopy, we demonstrated filament formation defects of desmin mutants, associated with arrhythmogenic right ventricular cardiomyopathy. To understand the pathogenesis of this disease, it is essential to analyze desmin filament structures under conditions in which both healthy and mutant desmin are expressed at equimolar levels mimicking an in vivo situation. Here, we applied dual color photoactivation localization microscopy using photoactivatable fluorescent proteins genetically fused to desmin and characterized the heterozygous status in living cells lacking endogenous desmin. In addition, we applied fluorescence resonance energy transfer to unravel short distance structural patterns of desmin mutants in filaments. For the first time, we present consistent high resolution data on the structural effects of five heterozygous desmin mutations on filament formation in vitro and in living cells. Our results may contribute to the molecular understanding of the pathological filament formation defects of heterozygous DES mutations in cardiomyopathies.