The use of lipids and fatty acids to measure the trophic plasticity of the coral Stylophora subseriata.

Following up on previous investigations on the stress resistance of corals, this study assessed the trophic plasticity of the coral Stylophora subseriata in the Spermonde Archipelago (Indonesia) along an eutrophication gradient. Trophic plasticity was assessed in terms of lipid content and fatty acid composition in the holobiont relative to its plankton (50-300 µm) food as well as the zooxanthellae density, lipid, FA and chlorophyll a content. A cross-transplantation experiment was carried out for 1.5 months in order to assess the trophic potential of corals. Corals, which live in the eutrophied nearshore area showed higher zooxanthellae and chlorophyll a values and higher amounts of the dinoflagellate biomarker FA 18:4n-3. Their lipid contents were maintained at similar to levels from specimens further away from the anthropogenic impact source going up to 14.9 ± 0.9 %. A similarity percentage analysis of the groups holobiont, zooxanthellae and plankton >55 µm found that differences between the FA composition of the holobiont and zooxanthellae symbionts were more distinct in the site closer to the shore, thus heterotrophic feeding became more important. Transplanted corals attained very similar zooxanthellae, chlorophyll a and lipid values at all sites as the specimens originating from those sites, which indicates a high potential for trophic plasticity in the case of a change in food sources, which makes this species competitive and resistant to eutrophication.

[Surgical management of vertebral column metastatic disease]. / Chirurgisches Management von Wirbelsäulenmetastasen.

The spine is the most frequent site of skeletal metastases. Among all spinal malignancies metastatic disease is most frequent and indicative of disseminating tumor disease. Depending on primary tumor entity, estimated survival time, general health status of the patient, presence of spinal instability and neurological deficits an oncological useful and patient-specific therapeutic intervention should be performed. New anterior approaches, resections and reconstruction techniques are making surgery a preferred method over radiation therapy. For differential indication of the multiple surgical treatment modalities prognostic scores are available to assist individual decision making. Indications for surgery include survival prognosis of minimum 3 months, intractable pain, progress of myelon compression and/or neurological deficits under radiochemotherapy, spinal instability and necessity for histological diagnosis. Resulting quality of life depends on efficient decompression of the spinal cord and restoration of spinal stability. To achieve these ultimate goals there are different anterior and posterior approaches, instrumentations and vertebral body replacement implants available. Preoperative embolization should be performed in hypervascular tumors, e.g., renal cell cancer. Vertebro-/Kyphoplasty as a percutaneous intervention should be considered for painful multisegmental disease and symptomatic osteolysis without epidural tumor compression to reach analgesia and stability. A multidisciplinary approach in patient selection, decision making and management is an essential precondition for complication avoidance and acceptable quality of life.

Effects of elevated atmospheric CO2 concentration on leaf dark respiration of Xanthium strumarium in light and in darkness.

Leaf dark respiration (R) is an important component of plant carbon balance, but the effects of rising atmospheric CO(2) on leaf R during illumination are largely unknown. We studied the effects of elevated CO(2) on leaf R in light (R(L)) and in darkness (R(D)) in Xanthium strumarium at different developmental stages. Leaf R(L) was estimated by using the Kok method, whereas leaf R(D) was measured as the rate of CO(2) efflux at zero light. Leaf R(L) and R(D) were significantly higher at elevated than at ambient CO(2) throughout the growing period. Elevated CO(2) increased the ratio of leaf R(L) to net photosynthesis at saturated light (A(max)) when plants were young and also after flowering, but the ratio of leaf R(D) to A(max) was unaffected by CO(2) levels. Leaf R(N) was significantly higher at the beginning but significantly lower at the end of the growing period in elevated CO(2)-grown plants. The ratio of leaf R(L) to R(D) was used to estimate the effect of light on leaf R during the day. We found that light inhibited leaf R at both CO(2) concentrations but to a lesser degree for elevated (17-24%) than for ambient (29-35%) CO(2)-grown plants, presumably because elevated CO(2)-grown plants had a higher demand for energy and carbon skeletons than ambient CO(2)-grown plants in light. Our results suggest that using the CO(2) efflux rate, determined by shading leaves during the day, as a measure for leaf R is likely to underestimate carbon loss from elevated CO(2)-grown plants.

Plant growth in elevated CO2 alters mitochondrial number and chloroplast fine structure.

With increasing interest in the effects of elevated atmospheric CO(2) on plant growth and the global carbon balance, there is a need for greater understanding of how plants respond to variations in atmospheric partial pressure of CO(2). Our research shows that elevated CO(2) produces significant fine structural changes in major cellular organelles that appear to be an important component of the metabolic responses of plants to this global change. Nine species (representing seven plant families) in several experimental facilities with different CO(2)-dosing technologies were examined. Growth in elevated CO(2) increased numbers of mitochondria per unit cell area by 1.3-2.4 times the number in control plants grown in lower CO(2) and produced a statistically significant increase in the amount of chloroplast stroma (nonappressed) thylakoid membranes compared with those in lower CO(2) treatments. There was no observable change in size of the mitochondria. However, in contrast to the CO(2) effect on mitochondrial number, elevated CO(2) promoted a decrease in the rate of mass-based dark respiration. These changes may reflect a major shift in plant metabolism and energy balance that may help to explain enhanced plant productivity in response to elevated atmospheric CO(2) concentrations.

Matrix proteins can generate the higher order architecture of the Golgi apparatus.

The Golgi apparatus in animal cells comprises a reticulum of linked stacks in the pericentriolar and often in the juxtanuclear regions of the cell. The unique architecture of this organelle is thought to depend on the cytoskeleton and cytoplasmic matrix proteins--the best characterized being the golgin family of fibrous, coiled-coil proteins and the GRASP family of stacking proteins. Here we show that these matrix proteins can be separated from oligosaccharide-modifying enzymes in the Golgi stack without affecting their ability to form a ribbon-like reticulum in the correct location near to the nucleus. Our data suggest that the Golgi is a structural scaffold that can exist independently of, but is normally populated by, the enzyme-containing membranes that modify transiting cargo. This new concept of the Golgi further indicates that the Golgi may be an autonomous organelle rather than one that is in simple dynamic equilibrium with the endoplasmic reticulum.

Elevated CO2 increases productivity and invasive species success in an arid ecosystem.

Arid ecosystems, which occupy about 20% of the earth's terrestrial surface area, have been predicted to be one of the most responsive ecosystem types to elevated atmospheric CO2 and associated global climate change. Here we show, using free-air CO2 enrichment (FACE) technology in an intact Mojave Desert ecosystem, that new shoot production of a dominant perennial shrub is doubled by a 50% increase in atmospheric CO2 concentration in a high rainfall year. However, elevated CO2 does not enhance production in a drought year. We also found that above-ground production and seed rain of an invasive annual grass increases more at elevated CO2 than in several species of native annuals. Consequently, elevated CO2 might enhance the long-term success and dominance of exotic annual grasses in the region. This shift in species composition in favour of exotic annual grasses, driven by global change, has the potential to accelerate the fire cycle, reduce biodiversity and alter ecosystem function in the deserts of western North America.

A complex of mammalian ufd1 and npl4 links the AAA-ATPase, p97, to ubiquitin and nuclear transport pathways.

The AAA-ATPase, p97/Cdc48p, has been implicated in many different pathways ranging from membrane fusion to ubiquitin-dependent protein degradation. Binding of the p47 complex directs p97 to act in the post-mitotic fusion of Golgi membranes. We now describe another binding complex comprising mammalian Ufd1 and Npl4. Yeast Ufd1p is required for ubiquitin-dependent protein degradation whereas yeast Npl4p has been implicated in nuclear transport. In rat liver cytosol, Ufd1 and Npl4 form a binary complex, which exists either alone or bound to p97. Ufd1/Npl4 competes with p47 for binding to p97 and so inhibits Golgi membrane fusion. This suggests that it is involved in another cellular function catalysed by p97, the most likely being ubiquitin-dependent events during mitosis. The fact that the binding of p47 and Ufd1/Npl4 is mutually exclusive suggests that these protein complexes act as adapters, directing a basic p97 activity into different cellular pathways.

The role of the tethering proteins p115 and GM130 in transport through the Golgi apparatus in vivo.

Biochemical data have shown that COPI-coated vesicles are tethered to Golgi membranes by a complex of at least three proteins: p115, giantin, and GM130. p115 binds to giantin on the vesicles and to GM130 on the membrane. We now examine the function of this tethering complex in vivo. Microinjection of an N-terminal peptide of GM130 or overexpression of GM130 lacking this N-terminal peptide inhibits the binding of p115 to Golgi membranes. Electron microscopic analysis of single microinjected cells shows that the number of COP-sized transport vesicles in the Golgi region increases substantially, suggesting that transport vesicles continue to bud but are less able to fuse. This was corroborated by quantitative immunofluorescence analysis, which showed that the intracellular transport of the VSV-G protein was significantly inhibited. Together, these data suggest that this tethering complex increases the efficiency with which transport vesicles fuse with their target membrane. They also provide support for a model of mitotic Golgi fragmentation in which the tethering complex is disrupted by mitotic phosphorylation of GM130.

The amino-terminal domain of the golgi protein giantin interacts directly with the vesicle-tethering protein p115.

Giantin is thought to form a complex with p115 and Golgi matrix protein 130, which is involved in the reassembly of Golgi cisternae and stacks at the end of mitosis. The complex is involved in the tethering of coat protomer I vesicles to Golgi membranes and the initial stacking of reforming cisternae. Here we show that the NH(2)-terminal 15% of Giantin suffices to bind p115 in vitro and in vivo and to block cell-free Golgi reassembly. Because Giantin is a long, rod-like protein anchored to the membrane by its extreme COOH terminus, these results support the idea of a long, flexible tether linking vesicles and cisternae.

Effects of short- and long-term elevated CO2 on the expression of ribulose-1,5-bisphosphate carboxylase/oxygenase genes and carbohydrate accumulation in leaves of Arabidopsis thaliana (L.) Heynh.

To investigate the proposed molecular characteristics of sugar-mediated repression of photosynthetic genes during plant acclimation to elevated CO2, we examined the relationship between the accumulation and metabolism of nonstructural carbohydrates and changes in ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) gene expression in leaves of Arabidopsis thaliana exposed to elevated CO2. Long-term growth of Arabidopsis at high CO2 (1000 microL L-1) resulted in a 2-fold increase in nonstructural carbohydrates, a large decrease in the expression of Rubisco protein and in the transcript of rbcL, the gene encoding the large subunit of Rubisco (approximately 35-40%), and an even greater decline in mRNA of rbcS, the gene encoding the small subunit (approximately 60%). This differential response of protein and mRNAs suggests that transcriptional/posttranscriptional processes and protein turnover may determine the final amount of leaf Rubisco protein at high CO2. Analysis of mRNA levels of individual rbcS genes indicated that reduction in total rbcS transcripts was caused by decreased expression of all four rbcS genes. Short-term transfer of Arabidopsis plants grown at ambient CO2 to high CO2 resulted in a decrease in total rbcS mRNA by d 6, whereas Rubisco content and rbcL mRNA decreased by d 9. Transfer to high CO2 reduced the maximum expression level of the primary rbcS genes (1A and, particularly, 3B) by limiting their normal pattern of accumulation through the night period. The decreased nighttime levels of rbcS mRNA were associated with a nocturnal increase in leaf hexoses. We suggest that prolonged nighttime hexose metabolism resulting from exposure to elevated CO2 affects rbcS transcript accumulation and, ultimately, the level of Rubisco protein.

Structure and mechanism of L-fucose isomerase from Escherichia coli.

The three-dimensional structure of L-fucose isomerase from Escherichia coli has been determined by X-ray crystallography at 2.5 A resolution. This ketol isomerase converts the aldose L-fucose into the corresponding ketose L-fuculose using Mn2+ as a cofactor. Being a hexamer with 64,976 Da per subunit, L-fucose isomerase is the largest structurally known ketol isomerase. The enzyme shows neither sequence nor structural similarity with other ketol isomerases. The hexamer obeys D3 symmetry and forms the crystallographic asymmetric unit. The strict and favorably oriented local symmetry allowed for a computational phase extension from 7.3 A to 2.5 A resolution. The structure was solved with an L-fucitol molecule bound to the catalytic center such that the hydroxyl groups at positions 1 and 2 are ligands of the manganese ion. Most likely, L-fucitol mimics a bound L-fucose molecule in its open chain form. The protein environment suggests strongly that the reaction belongs to the ene-diol type.

Annexin I targets S100C to early endosomes.

Immunofluorescence and subcellular fractionation localize annexin I and the EF hand protein S100C to the same membranous structures which in part correspond to transferrin receptor-positive endosomes. The association of S100C with endosomal membranes is strictly dependent on annexin I binding since a D91stop-S100C mutant protein, in which the residues essential for annexin I binding have been removed, fails to colocalize with membraneous structures. This indicates that annexin I and S100C form a complex in vivo and that the endosomal localization of this complex is mediated through an interaction of annexin I with the endosomal membrane.

Chiral discrimination using piezoelectric and optical gas sensors.

Odour perception in humans can sometimes discriminate different enantiomers of a chiral compound, such as limonene. Chiral discrimination represents one of the greatest challenges in attempts to devise selective and sensitive gas sensors. The importance of such discrimination for pharmacology is dear, as the physiological effect of enantiomers of drugs and other biologically active molecules may differ significantly. Here we describe two different sensor systems that are capable of recognizing different enantiomers and of qualitatively monitoring the enantiomeric composition of amino-acid derivatives and lactates in the gas phase. One sensor detects changes in mass, owing to binding of the compound being analysed (the 'analyte'), by thickness shear-mode resonance; the other detects changes in the thickness of a surface layer by reflectometric interference spectroscopys. Both devices use the two enantiomers of a chiral polymeric receptor, and offer rapid on-line detection of chiral species with high selectivity.

Identification and characterization of a novel type of annexin-membrane interaction: Ca2+ is not required for the association of annexin II with early endosomes.

Annexin II, a member of a family of Ca2+ and membrane binding proteins, has been implicated in regulating membrane organization and membrane transport during endocytosis and Ca2+ regulated secretion. To characterize the mechanistic aspects of the annexin. II action we studied parameters which determine the endosomal association of annexin II. Immunoblot analysis of subcellular membrane fractions prepared from BHK cells in the presence of a Ca2+ chelating agent reveals that annexin II remains associated with endosomal membranes under such conditions. This annexin II behaviour is atypical for the Ca2+ regulated annexins and is corroborated by the finding that ectopically expressed annexin II mutants with inactivated Ca2+ binding sites continue to co-fractionate with endosomal membranes. The Ca(2+)-independent membrane association of annexin II is also not affected by introducing mutations interfering with the complex formation of annexin II with its intracellular protein ligand p11. However, a deletion of the unique N-terminal domain of annexin II, in particular the sequence spanning residues 15 to 24, abolishes the Ca(2+)-independent association of the protein with endosomes. These results describe a novel, Ca(2+)-independent type of annexin-membrane interaction and provide a first explanation for the observed preference of different annexins for different cellular membranes. In the case of annexin II this specificity could be mediated through specific membrane receptors interacting with a unique sequence in the annexin II molecule.

Chiral discrimination in the gas phase using different transducers: thickness shear mode resonators and reflectometric interference spectroscopy.

The discrimination of optical isomers (enantiomers) in the gas phase has been performed using two different analytical tools: thickness shear mode resonators (TSMRs) and reflectometric interference spectroscopy (RIFS). The selective coatings included both enantiomers ((S)- and (R)-receptor) of a Chirasil-Val derivative (stationary phase material in GC) with octyl side chains. Successful discrimination of the enantiomers of different types of analytes (amino acids and lactates) was achieved. The results of both transduction methods were consistent and in good agreement with GC measurements. In addition, different mixtures of both enantiomers of the respective analyte were measured, and the enantiomeric composition could be quantitatively determined with excellent reliability. Since the sensors allow on-line monitoring (not possible with GC) of enantiomeric purity, an application in industrial synthesis (process control) of such compounds represents an interesting feature, especially with regard to the tested derivatives of lactic acid.

Influence of Plant Growth at High CO2 Concentrations on Leaf Content of Ribulose-1,5-Bisphosphate Carboxylase/Oxygenase and Intracellular Distribution of Soluble Carbohydrates in Tobacco, Snapdragon, and Parsley.

We have examined the possible role of leaf cytosolic hexoses and the expression of mannitol metabolism as mechanisms that may affect the repression of photosynthetic capacity when plants are grown at 1000 versus 380 [mu]L L-1 CO2. In plants grown at high CO2, leaf ribulose-1,5-bisphosphate carboxylase/oxygenase content declined by [greater than or equal to]20% in tobacco (Nicotiana sylvestris) but was not affected in the mannitol-producing species snapdragon (Antirrhinum majus) and parsley (Petroselinum hortense). In the three species mesophyll glucose and fructose at midday occurred almost entirely in the vacuole (>99%), irrespective of growth CO2 levels. The estimated cytosolic concentrations of glucose and fructose were [less than or equal to]100 [mu]M. In the three species grown at high CO2, total leaf carbohydrates increased 60 to 100%, but mannitol metabolism did not function as an overflow mechanism for the increased accumulation of carbohydrate. In both snapdragon and parsley grown at ambient or high CO2, mannitol occurred in the chloroplast and cytosol at estimated midday concentrations of 0.1 M or more each. The compartmentation of leaf hexoses and the metabolism of alternate carbohydrates are further considered in relation to photosynthetic acclimation to high levels of CO2.

Structural requirements for annexin I-S100C complex-formation.

S100C is a member of the S100 family of EF-hand-type Ca(2+)-binding proteins which are thought to bind to and thereby regulate the activity of cellular target proteins in a Ca(2+)-dependent manner. An intracellular ligand for S100C is the Ca2+/phospholipid-binding protein annexin I and we show here that complex-formation is mediated through unique domains within S100C and annexin I. Using a proteolytically truncated annexin I derivative as well as a number of N-terminal annexin I peptides in liposome co-pelleting and ligand-blotting assays we map the S100C-binding site to the N-terminal 13 residues of annexin I. Similar analyses employing recombinantly expressed S100C mutants reveal that residues D91 to 194 in the unique C-terminal extension of this S100 protein are indispensable for annexin I binding. Interaction between S100C and an N-terminal annexin I peptide containing a tryptoplan at position 11 can also be monitored by fluorescence emission spectroscopy after tryptophan excitation. This analysis indicates that the local environment of the tryptophan in annexin I becomes less aqueous on S100C binding, suggesting a hydrophobic nature of the protein-protein interaction. Thus the structural basis of the annexin 1-S100C complex-formation probably resembles to a large extent that of the well-characterized annexin II-p11 interaction.

EcoCELLs: tools for mesocosm scale measurements of gas exchange.

We describe the use of a unique plant growth facility, which has as its centerpiece four 'EcoCELLs', or 5x7 m mesocosms designed as open-flow, mass-balance systems for the measurement of carbon, water and trace gas fluxes. This system is unique in that it was conceived specifically to bridge the gap between measurement scales during long-term experiments examining the function and development of model ecosystems. There are several advantages to using EcoCELLs, including (i) the same theory of operation as leaf level gas exchange systems, but with continuous operation at a much larger scale; (ii) the ability to independently evaluate canopy-level and ecosystem models; (iii) simultaneous manipulation of environmental factors and measurement of system-level responses, and (iv) maximum access to, and manipulation of, a large rooting volume. In addition to discussing the theory, construction and relative merits of EcoCELLs, we describe the calibration and use of the EcoCELLs during a 'proof of concept' experiment. This experiment involved growing soybeans under two ambient CO2 concentrations (approximately 360 and 710 micromoles mol-1). During this experiment, we asked 'How accurate is the simplest model that can be used to scale from leaf-level to canopy-level responses?' in order to illustrate the utility of the EcoCELLs in validating canopy-scale models.