Rhodospirillum salinarum sp. nov., a halophilic photosynthetic bacterium isolated from a Portuguese saltern

A new species of halophilic photosynthetic bacteria, Rhodospirillum salinarum, has been isolated and described. Its natural habitat are the terminal crystallization ponds of solar salt production plants. R. salinarum grows optimally at 42°C in the presence of 6–18% NaCl (w/v). Growth requirements are complex, yeast extract and peptone being required both for aerobic heterotrophic and for anaerobic phototrophic growth. Increasing concentrations of NaCl in the growth media did not give rise to any corresponding increase in intracellular concentrations of K⁺, Na⁺, polyalcohols or amino acids. Malate dehydrogenase from R. salinarum is not halophilic, being inhibited even at low concentrations of Na⁺ or K⁺. The GC mol % of DNA from R. salinarum is markedly higher than that for DNA from R. salexigens, the only previously described halophilic species of the genus Rhodospirillum.     

Mobility of individual roach <Emphasis Type="Italic">Rutilus rutilus</Emphasis> (L.) in three weir-fragmented Belgian rivers

Adult roach Rutilus rutilus (L.) (N = 24; 19.9–36.1 cm FL) from three highly fragmented Belgian rivers were tagged with surgically implanted radio transmitters. Their seasonal movements were observed from March to August 2004 (circum reproduction period) in river stretches delimited by two physical barriers. In the three rivers, roach displayed similar patterns of movements which were mainly influenced by the date of observation (movements increased in late April–May) and water temperature (travel distances were more important when water temperature ranged between 10°C and 14°C). Roach sometimes cleared physical obstacles. The mean distances travelled in each river were relatively short (max. 2.5 km) and mainly influenced by the length of the study reach, which was delimited by physical barriers.     

Lipopolysaccharide-induced gene expression in murine macrophages is enhanced by prior exposure to oxLDL

Uptake of modified lipoproteins by macrophages results in the formation of foam cells. We investigated how foam cell formation affects the inflammatory response of macrophages. Murine bone marrow-derived macrophages were treated with oxidized LDL (oxLDL) to induce foam cell formation. Subsequently, the foam cells were activated with lipopolysaccharide (LPS), and the expression of lipid metabolism and inflammatory genes was analyzed. Furthermore, gene expression profiles of foam cells were analyzed using a microarray. We found that prior exposure to oxLDL resulted in enhanced LPS-induced tumor necrosis factor (TNF) and interleukin-6 (IL-6) gene expression, whereas the expression of the anti-inflammatory cytokine IL-10 and interferon-beta was decreased in foam cells. Also, LPS-induced cytokine secretion of TNF, IL-6, and IL-12 was enhanced, whereas secretion of IL-10 was strongly reduced after oxLDL preincubation. Microarray experiments showed that the overall inflammatory response induced by LPS was enhanced by oxLDL loading of the macrophages. Moreover, oxLDL loading was shown to result in increased nuclear factor-kappaB activation. In conclusion, our experiments show that the inflammatory response to LPS is enhanced by loading of macrophages with oxLDL. These data demonstrate that foam cell formation may augment the inflammatory response of macrophages during atherogenesis, possibly in an IL-10-dependent manner.     

The role of medial temporal lobe structures in implicit learning: an event-related FMRI study

The medial temporal lobe (MTL) has been associated with declarative learning of flexible relational rules and the basal ganglia with implicit learning of stimulus-response mappings. It remains an open question of whether MTL or basal ganglia are involved when learning flexible relational contingencies without awareness. We studied learning of an explicit stimulus-response association with fMRI. Embedded in this explicit task was a hidden structure that was learnt implicitly. Implicit learning of the sequential regularities of the "hidden rule" activated the ventral perirhinal cortex, within the MTL, whereas learning the fixed stimulus-response associations activated the basal ganglia, indicating that the function of the MTL and the basal ganglia depends on the learned material and not necessarily on the participants' awareness.     

Bovine Brain Myelin Glycerophosphocholine Choline Phosphodiesterase is an Alkaline Lysosphingomyelinase of the eNPP-Family, Regulated by Lysosomal Sorting

Glycerophosphocholine choline phosphodiesterase (GPC-Cpde) is a glycosylphosphatidylinositol (GPI)-anchored alkaline hydrolase that is expressed in the brain and kidney. In brain the hydrolase is synthesized by the oligodendrocytes and expressed on the myelin membrane. There are two forms of brain GPC-Cpde, a membrane-linked (mGPC-Cpde) and a soluble (sGPC-Cpde). Here we report the characterisation sGPC-Cpde from bovine brain. The amino acid sequence was identical to ectonucleotide pyrophosphatase/phosphodiesterase 6 (eNPP6) precursor, lacking the N-terminal signal peptide region and a C-terminal stretch, suggesting that the hydrolase was solubilised by C-terminal proteolysis, releasing the GPI-anchor. sGPC-Cpde existed as two isoforms, a homodimer joined by a disulfide bridge linking C414 from each monomer, and a monomer resulting from proteolysis N-terminally to this disulfide bond. The only internal disulfide bridge, linking C142 and C154, stabilises the choline-binding pocket. sGPC-Cpde was specific for lysosphingomyelin, displaying 1 to 2 orders of magnitude higher catalytic activity than towards GPC and lysophosphatidylcholine, suggesting that GPC-Cpde may function in the sphingomyelin signaling, rather than in the homeostasis of acylglycerophosphocholine metabolites. The truncated high mannose and bisected hybrid type glycans linked to N118 and N341 of sGPC-Cpde is a hallmark of glycans in lysosomal glycoproteins, subjected to GlcNAc-1-phosphorylation en route through Golgi. Thus, sGPC-Cpde may originate from the lysosomes, suggesting that lysosomal sorting contributes to the level of mGPC-Cpde on the myelin membrane.     

Development of floating rafts after the rewetting of cut-over bogs: the importance of peat quality

The usual method of restoring cut-over bogs is to rewet the peat surface, but this often leads to the remaining peat layers being deeply inundated. For Sphagnum-dominated vegetation to develop at deeply inundated locations, it is important for floating rafts of buoyant residual peat to develop. In this study, the chemical and physical characteristics of buoyant and inundated peat collected from rewetted cut-over bog were compared. In general, buoyant peat was poorly humified; high methane (CH₄) production rates (≥2?µmol?g^?1?DW?day^?1) were important to ensure buoyancy. Although the peat water CH₄ concentrations increased with depth, the CH₄ production rates were higher in the uppermost peat layers. High CH₄ production rates were related positively with P concentrations and negatively with lignin concentrations. The pH to bulk density ratio (≥0.05) also appeared to be a good indicator of CH₄ production rates, providing an easy and cheap way to measure the variable for restoration practitioners. Our results indicated that analysing certain simple characteristics of the residual peat can greatly improve the success of the rewetting measures taken in cut-over bogs. If the analysis reveals that the residual peat is unsuitable for floating raft formation, deep inundation is inappropriate unless suitable peat from other locations can be introduced.     

In vivo modulation of extracellular hippocampal glutamate and GABA levels and limbic seizures by group I and II metabotropic glutamate receptor ligands

The effects of several metabotropic receptor (mGluR) ligands on baseline hippocampal glutamate and GABA overflow in conscious rats and the modulation of limbic seizure activity by these ligands were investigated. Intrahippocampal mGluR group I agonist perfusion via a microdialysis probe [1 mm (R,S)-3,5-dihydroxyphenylglycine] induced seizures and concomitant augmentations in amino acid dialysate levels. The mGlu1a receptor antagonist LY367385 (1 mm) decreased baseline glutamate but not GABA concentrations, suggesting that mGlu1a receptors, which regulate hippocampal glutamate levels, are tonically activated by endogenous glutamate. This decrease in glutamate may contribute to the reported LY367385-mediated anticonvulsant effect. The mGlu5 receptor antagonist 2-methyl-6-(phenylethynyl)-pyridine (50 mg/kg) also clearly abolished pilocarpine-induced seizures. Agonist-mediated actions at mGlu2/3 receptors by LY379268 (100 microm, 10 mg/kg intraperitoneally) decreased basal hippocampal GABA but not glutamate levels. This may partly explain the increased excitation following systemic LY379268 administration and the lack of complete anticonvulsant protection within our epilepsy model with the mGlu2/3 receptor agonist. Group II selective mGluR receptor blockade with LY341495 (1-10 microm) did not alter the rats' behaviour or hippocampal amino acid levels. These data provide a neurochemical basis for the full anticonvulsant effects of mGlu1a and mGlu5 antagonists and the partial effects observed with mGlu2/3 agonists in vivo.     

A tandem affinity purification-based technology platform to study the cell cycle interactome in Arabidopsis thaliana

Defining protein complexes is critical to virtually all aspects of cell biology because many cellular processes are regulated by stable protein complexes, and their identification often provides insights into their function. We describe the development and application of a high throughput tandem affinity purification/mass spectrometry platform for cell suspension cultures to analyze cell cycle-related protein complexes in Arabidopsis thaliana. Elucidation of this protein-protein interaction network is essential to fully understand the functional differences between the highly redundant cyclin-dependent kinase/cyclin modules, which are generally accepted to play a central role in cell cycle control, in all eukaryotes. Cell suspension cultures were chosen because they provide an unlimited supply of protein extracts of actively dividing and undifferentiated cells, which is crucial for a systematic study of the cell cycle interactome in the absence of plant development. Here we report the mapping of a protein interaction network around six known core cell cycle proteins by an integrated approach comprising generic Gateway-based vectors with high cloning flexibility, the fast generation of transgenic suspension cultures, tandem affinity purification adapted for plant cells, matrix-assisted laser desorption ionization tandem mass spectrometry, data analysis, and functional assays. We identified 28 new molecular associations and confirmed 14 previously described interactions. This systemic approach provides new insights into the basic cell cycle control mechanisms and is generally applicable to other pathways in plants.