Showing papers by "University of Konstanz published in 2003"

Genome Duplication, a Trait Shared by 22,000 Species of Ray-Finned Fish

Abstract: Through phylogeny reconstruction we identified 49 genes with a single copy in man, mouse, and chicken, one or two copies in the tetraploid frog Xenopus laevis, and two copies in zebrafish (Danio rerio). For 22 of these genes, both zebrafish duplicates had orthologs in the pufferfish (Takifugu rubripes). For another 20 of these genes, we found only one pufferfish ortholog but in each case it was more closely related to one of the zebrafish duplicates than to the other. Forty-three pairs of duplicated genes map to 24 of the 25 zebrafish linkage groups but they are not randomly distributed; we identified 10 duplicated regions of the zebrafish genome that each contain between two and five sets of paralogous genes. These phylogeny and synteny data suggest that the common ancestor of zebrafish and pufferfish, a fish that gave rise to approximately 22000 species, experienced a large-scale gene or complete genome duplication event and that the pufferfish has lost many duplicates that the zebrafish has retained.

Allelopathy of Aquatic Autotrophs

Abstract: Allelopathy in aquatic environments may provide a competitive advantage to angiosperms, algae, or cyanobacteria in their interaction with other primary producers. Allelopathy can influence the competition between different photoautotrophs for resources and change the succession of species, for example, in phytoplankton communities. Field evidence and laboratory studies indicate that allelopathy occurs in all aquatic habitats (marine and freshwater), and that all primary producing organisms (cyanobacteria, micro- and macroalgae as well as angiosperms) are capable of producing and releasing allelopathically active compounds. Although allelopathy also includes positive (stimulating) interactions, the majority of studies describe the inhibitory activity of allelopathically active compounds. Different mechanisms operate depending on whether allelopathy takes place in the open water (pelagic zone) or is substrate associated (benthic habitats). Allelopathical interactions are especially common in fully aquatic s...

Interacting quintessence solution to the coincidence problem

Abstract: We show that a suitable interaction between a scalar field and a matter fluid in a spatially homogeneous and isotropic spacetime can drive the transition from a matter dominated era to an accelerated expansion phase and simultaneously solve the coincidence problem of our present Universe. For this purpose we study the evolution of the energy density ratio of these two components. We demonstrate that a stationary attractor solution is compatible with an accelerated expansion of the Universe. We extend this study to account for dissipation effects due to interactions in the dark matter fluid. Finally, type Ia supernovae and primordial nucleosynthesis data are used to constrain the parameters of the model.

NKT cells enhance CD4+ and CD8+ T cell responses to soluble antigen in vivo through direct interaction with dendritic cells.

Abstract: Modification in the function of dendritic cells (DC), such as that achieved by microbial stimuli or T cell help, plays a critical role in determining the quality and size of adaptive responses to Ag. NKT cells bearing an invariant TCR ( i NKT cells) restricted by nonpolymorphic CD1d molecules may constitute a readily available source of help for DC. We therefore examined T cell responses to i.v. injection of soluble Ag in the presence or the absence of i NKT cell stimulation with the CD1d-binding glycolipid α-galactosylceramide (α-GalCer). Considerably enhanced CD4 + and CD8 + T cell responses were observed when α-GalCer was administered at the same time as or close to OVA injection. This enhancement was dependent on the involvement of i NKT cells and CD1d molecules and required CD40 signaling. Studies in IFN-γR −/− mice indicated that IFN-γ was not required for the adjuvant effect of α-GalCer. Consistent with this result, enhanced T cell responses were observed using OCH, an analog of α-GalCer with a truncated sphingosine chain and a reduced capacity to induce IFN-γ. Splenic DC from α-GalCer-treated animals expressed high levels of costimulatory molecules, suggesting maturation in response to i NKT cell activation. Furthermore, studies with cultured DC indicated that potentiation of T cell responses required presentation of specific peptide and α-GalCer by the same DC, implying conditioning of DC by i NKT cells. The i NKT-enhanced T cell responses resisted challenge with OVA-expressing tumors, whereas responses induced in the absence of i NKT stimulation did not. Thus, i NKT cells exert a significant influence on the efficacy of immune responses to soluble Ag by modulating DC function.

A Nation-Wide Laboratory: Examining Trust and Trustworthiness by Integrating Behavioral Experiments into Representative Surveys

Abstract: Die experimentelle Okonomie fuhrt typischerweise Labor-Untersuchungen durch, die mit homogenen und selektiven Versuchspersonen arbeiten. Reprasentative Surveys leiden hingegen unter Mesfehlern und der Frage, ob hypothetisches Verhalten, das erhoben wird, mit tatsachlichem Verhalten korrespondiert. Deswegen prasentieren wir eine Methode, mit der man die Schwachen beider Ansatze uberwindet, indem man Survey-Daten mit Experimenten kombiniert. Die von uns entwickelte Methode hat den Vorzug, dass sie es auf preiswerte Art und Weise erlaubt, Experimente, die die Interaktion zweier Personen erfordern, mit Standard-Surveys zu kombinieren, die auf der Unabhangigkeit der befragten Personen beruhen. Wir illustrieren die Moglichkeiten unserer Methodik mit einer Untersuchung uber Vertrauen und Vertrauenswurdigkeit in Deutschland, bei der eine reprasentative Umfrage mit einem Experiment uber eine Dilemma-Situation verbunden wurde. Unsere Resultate zeigen zum einen, dass nicht alle Survey-Fragen uber Vertrauen mit den Ergebnissen des Experiments korrelieren. Zum zweiten zeigen unsere Ergebnisse, dass altere Menschen (65 Jahre und alter), Hochqualifizierte und Personen, die in grosseren Haushalten leben, im Experiment unterdurchschnittlich Vertrauen offenbaren. Fur Auslander, Katholiken und die Anhanger der grosen Volksparteien finden wir uberdurchschnittliches Vertrauen. Vertrauenswurdigkeit bzw. Altruismus zeigen im Experiment Altere und Befragte mit gutem Gesundheitszustand. Unterdurchschnittliche Vertrauenswudigkeit bzw. Altruismus zeigen jungere Befragte (bis zu 35 Jahren), arbeitslos Gemeldete und Befragte ohne eine Parteineigung.

Dark Networks as Problems

Abstract: Networks and networking are viewed as ways of dealing with complex problems that beset both the state and society. Homelessness, health care, and crime are all viewed as problems that networks can manage better than single organizations can. This article views these problems as networks that must be confronted if Western democracies wish to deal with terrorism, drug smuggling, and the manifold pathologies that confront failed states. In this article we adopt the perspective of networks as problems. The majority of the literature on networks and collaboration is quite positive. Collaborative networks are seen as appropriate devices to tackle public management problems and successfully coordinate political, social, and economic action. From the level of global governance, European integration, sectoral policy networks at the national level, and service implementation networks at the local level, these devices are all viewed as ways of solving governance problems in a complex and differentiated world. The research proposed here intends to develop a more holistic view of this phenomenon by looking at dark networks. The article tries to evaluate how network structures and governance are used for criminal or immoral ends. Because the judgment of ends is inherently normative, we propose to talk about overt and legal versus covert and illegal networks. We then analyze where the similarities and differences between the two sets are and what we might be able to learn regarding both forms if we mirror them against each other. The article develops a set of propositions drawn from selected cases of drug-trafficking networks, the diamond and weapons trade, and the Al Qaeda terrorist network. Most of the literature on networks and collaboration is quite positive. Collaborative networks are seen as appropriate devices to tackle public management problems and to successfully coordinate political, social, and economic action. Figure 1 portrays a familiar relationship between public organizations and problems. Each organization (01, 02, 03, and 04) intersects with only part of the problem, and none of the organizations is linked in any kind of a A first version of this article was presented at the International Conference on the Empirical Study of Governance, Management, and Performance, Barcelona, 4-5 October 2002. We would like to thank the participants of the conference, especially Larry O'Toole, for their helpful comments on the revision of this article. DOI: 10.1093/jopart/mug029 Journal of Public Administration Research and Theory, Vol. 13, no. 4, pp. 413-439 c 2003 Journal of Public Administration Research and Theory, Inc. This content downloaded from 207.46.13.15 on Sat, 23 Apr 2016 05:07:31 UTC All use subject to http://about.jstor.org/terms 414 Journal of Public Administration Research and Theory Figure 1 The Rationale for Network Collaboration

High Glucose Causes Upregulation of Cyclooxygenase-2 and Alters Prostanoid Profile in Human Endothelial Cells Role of Protein Kinase C and Reactive Oxygen Species

Abstract: Background— Prostaglandins generated by cyclooxygenase (COX) have been implicated in hyperglycemia-induced endothelial dysfunction. However, the role of individual COX isoenzymes as well as the molecular mechanisms linking oxidative stress and endothelial dysfunction in diabetes remains to be clarified. Methods and Results— Human aortic endothelial cells were exposed to normal (5.5 mmol/L) and high (22.2 mmol/L) glucose. Glucose selectively increased mRNA and protein expression of COX-2. Its upregulation was associated with an increase of thromboxane A2 and a reduction of prostacyclin (PGI2) release. Glucose-induced activation of PKC resulted in the formation of peroxynitrite and tyrosine nitration of PGI2 synthase. NO release was reduced despite 2-fold increase of endothelial NO synthase expression. Phorbol ester caused an increase of COX-2 and endothelial NO synthase expression similar to that elicited by glucose. These effects were prevented by the PKC inhibitor calphostin C. N-acetylcysteine, vitamin ...

Attention and emotion: an ERP analysis of facilitated emotional stimulus processing.

Abstract: Recent event-related potential studies observed an early posterior negativity (EPN) reflecting facilitated processing of emotional images. The present study explored if the facilitated processing of emotional pictures is sustained while subjects perform an explicit non-emotional attention task. EEG was recorded from 129 channels while subjects viewed a rapid continuous stream of images containing emotional pictures as well as task-related checkerboard images. As expected, explicit selective attention to target images elicited large P3 waves. Interestingly, emotional stimuli guided stimulus-driven selective encoding as reflected by augmented EPN amplitudes to emotional stimuli, in particular to stimuli of evolutionary significance (erotic contents, mutilations, and threat). These data demonstrate the selective encoding of emotional stimuli while top-down attentional control was directed towards non-emotional target stimuli.

Origin of the superflock of cichlid fishes from Lake Victoria, East Africa.

Abstract: Lake Victoria harbors a unique species-rich flock of more than 500 endemic haplochromine cichlid fishes. The origin, age, and mechanism of diversification of this extraordinary radiation are still debated. Geological evidence suggests that the lake dried out completely about 14,700 years ago. On the basis of phylogenetic analyses of almost 300 DNA sequences of the mitochondrial control region of East African cichlids, we find that the Lake Victoria cichlid flock is derived from the geologically older Lake Kivu. We suggest that the two seeding lineages may have already been lake-adapted when they colonized Lake Victoria. A haplotype analysis further shows that the most recent desiccation of Lake Victoria did not lead to a complete extinction of its endemic cichlid fauna and that the major lineage diversification took place about 100,000 years ago.

Stress in organizations

Abstract: This chapter summarizes research on stress in organizations. We give an introduction into the concepts of stress, stressors, and stress reactions. We present theories on organizational stress and review evidence from empirical research. Particularly, we focus on observational and longitudinal studies that show that stressors at work have a detrimental effect on health and well-being. We discuss resources such as control at work, social support, coping styles, and self-esteem as potential moderators in the stress process. We describe findings from laboratory and field studies on stress and its effect on performance. We address the question whether stress is related to other organizational variables, including organizational commitment, absenteeism, and turnover. We review research findings on stress interventions and discuss stressor reduction, increase of resource, strain reduction, and life-style change as major stress intervention approaches. We suggest directions for future research for increasing knowledge about stress in organizations. Keywords: health; longitudinal research; performance; resources; stress; stress intervention; well-being

Co-citation analysis and the search for invisible colleges: A methodological evaluation

Abstract: After 30 years of research, co-citation analysis has become the dominant method for the empirical study of the structures of scientific communication. There is a considerable variety of methods and, at the same time, a lack of methodological evaluation. This paper summarizes the present state of co-citation analysis and presents several methods of clustering references. The database used is a selection of 2,114 documents in the field of organization studies from 1986-2000. The evaluative study shows that the choice of methods has a strong impact on the results created. It also shows that the methods of cluster and factor analysis hitherto used have only a limited value in differentiating clearly between schools of scientific research - the 'invisible colleges'.

BESA source coherence: a new method to study cortical oscillatory coupling.

Abstract: This paper introduces source coherence, a new method for the analysis of cortical coherence using noninvasive EEG and MEG data. Brain electrical source analysis (BESA) is applied to create a discrete multiple source model. This model is used as a source montage to transform the recorded data from sensor level into brain source space. This provides source waveforms of the modeled brain regions as a direct measure for their activities on a single trial basis. The source waveforms are transformed into time-frequency space using complex demodulation. Magnitude-squared coherence between the brain sources reveals oscillatory coupling between sources. This procedure allows one to separate the time-frequency content of different brain regions even if their activities severely overlap at the surface. Thus, source coherence overcomes problems of localization and interpretation that are inherent to coherence analysis at sensor level. The principle of source coherence is illustrated using an EEG recording of an error-related negativity as an example. In this experiment the subject performed a visuo-motor task. Source coherence analysis revealed dynamical linking between posterior and central areas within the gamma-band around the time of button press at a post-stimulus latency of 200-300 ms.

The determination of ecological status in shallow lakes - a tested system (ECOFRAME) for implementation of the European Water Framework Directive

Abstract: 1. The European Water Framework Directive requires the determination of ecological status in European fresh and saline waters. This is to be through the establishment of a typology of surface water bodies, the determination of reference (high status) conditions in each element (ecotype) of the typology and of lower grades of status (good, moderate, poor and bad) for each ecotype. It then requires classification of the status of the water bodies and their restoration to at least 'good status' in a specified period. 2. Though there are many methods for assessing water quality, none has the scope of that defined in the Directive. The provisions of the Directive require a wide range of variables to be measured and give only general guidance as to how systems of classification should be established. This raises issues of comparability across States and of the costs of making the determinations. 3. Using expert workshops and subsequent field testing, a practicable pan-European typology and classification system has been developed for shallow lakes, which can easily be extended to all lakes. It is parsimonious in its choice of determinands, but based on current limnological understanding and therefore as cost-effective as possible. 4. A core typology is described, which can be expanded easily in particular States to meet local conditions. The core includes 48 ecotypes across the entire European climate gradient and incorporates climate, lake area, geology of the catchment and conductivity. 5. The classification system is founded on a liberal interpretation of Annexes in the Directive and uses variables that are inexpensive to measure and ecologically relevant. The need for taxonomic expertise is minimized. 6. The scheme has been through eight iterations, two of which were tested in the field on tranches of 66 lakes. The final version, Version 8, is offered for operational testing and further refinement by statutory authorities.

Developmental integration in a complex morphological structure: how distinct are the modules in the mouse mandible?

Abstract: SUMMARY The mouse mandible has long served as a model system for studying the development and evolution of complex morphological structures. We used the methods of geometric morphometrics to reassess the hypothesis that the mandible consists of two separate modules: an anterior part bearing the teeth and a posterior part with muscle attachment surfaces and articulating with the skull. The analyses particularly focused on covariation of fluctuating asymmetry, because such covariation is due exclusively to direct interactions between the developmental processes that produce the traits of interest, whereas variation of traits among individuals also reflects other factors. The patterns of fluctuating asymmetry and individual variation were only partly consistent, indicating that developmental processes contribute differentially to variation at different levels. The results were in agreement with the hypothesis that the anterior and posterior parts of the mandible are separate developmental modules. Comparison of all alternative partitions of the landmarks into two contiguous subsets confirmed the hypothesis for the location of the boundary between modules but also underscored that the separation between them is not complete. Modularity is therefore manifest as the relative independence of parts within the framework of overall integration of the mandible as a wholeFit is a matter of degrees, not all or nothing.

Functional consequences of oxidative membrane damage

Abstract: The interaction of reactive oxygen species with biological membranes is known to produce a great variety of different functional modifications. Part of these modifications may be classified as direct effects. They are due to direct interaction of the reactive species with the molecular machinery under study with a subsequent chemical and functional modification of these molecules. An important part of the observed functional modifications are, however, indirect effects. They are the consequence of an oxidative modification of the environment of biological macromolecules. Lipid peroxidation—via its generation of chemically reactive products—contributes to the loss of cellular functions through the inactivation of membrane enzymes and even of cytoplasmic (i.e., water soluble) proteins. Oxidation of membrane lipids may, however, also increase the efficiency of membrane functions. This was observed for a series of transport systems. Lipid peroxidation was accompanied by activation of certain types of ion channels and ion carriers. The effect is due to an increase of the polarity of the membrane interior by accumulation of polar oxidation products. The concomitant change of the dielectric constant, which may be detected via the increase of the membrane capacitance, facilitates the opening of membrane channels and lowers the inner membrane barrier for the movement of ions across the membrane. The predominant effect, however, at least at a greater extent of lipid peroxidation, is the inhibition of membrane functions. The strong increase of the leak conductance contributes to the depolarization of the membrane potential, it destroys the barrier properties of the membrane and it may finally lead, via an increase of cytoplasmic Ca2+ concentration, to cell death. The conclusions were derived from experiments performed with different systems: model systems in planar lipid membranes, native ion channels either reconstituted in lipid membranes or investigated in their natural environment by the patch-clamp method, and two important ion pumps, the Na/K-ATPase and the sarcoplasmic reticulum (SR) Ca-ATPase.

Multiple overseas dispersal in amphibians

Abstract: Amphibians are thought to be unable to disperse over ocean barriers because they do not tolerate the osmotic stress of salt water. Their distribution patterns have therefore generally been explaine...

VIVID is a flavoprotein and serves as a fungal blue light photoreceptor for photoadaptation

Abstract: Blue light regulates many physiological and developmental processes in fungi. Most of the blue light responses in the ascomycete Neurospora crassa are dependent on the two blue light regulatory proteins White Collar (WC)-1 and -2. WC-1 has recently been shown to be the first fungal blue light photoreceptor. In the present study, we characterize the Neurospora protein VIVID. VIVID shows a partial sequence similarity with plant blue light photoreceptors. In addition, we found that VIVID non-covalently binds a flavin chromophore. Upon illumination with blue light, VIVID undergoes a photocycle indicative of the formation of a flavin-cysteinyl adduct. VVD is localized in the cytoplasm and is only present after light induction. A loss-of-function vvd mutant was insensitive to increases in light intensities. Furthermore, mutational analysis of the photoactive cysteine indicated that the formation of a flavin-cysteinyl adduct is essential for VIVID functions in vivo. Our results show that VIVID is a second fungal blue light photoreceptor which enables Neurospora to perceive and respond to daily changes in light intensity.

Absence of sterols constrains carbon transfer between cyanobacteria and a freshwater herbivore (Daphnia galeata)

Abstract: A key process in freshwater plankton food webs is the regulation of the efficiency of energy and material transfer. Cyanobacterial carbon (C) in particular is transferred very inefficiently to herbivorous zooplankton, which leads to a decoupling of primary and secondary production and the accumulation of cyanobacterial biomass, which is associated with reduced recreational quality of water bodies and hazards to human health. A recent correlative field study suggested that the low transfer efficiency of cyanobacterial C is the result of the absence of long-chain polyunsaturated fatty acids (PUFA) in the diet of the zooplankton. By supplementation of single-lipid compounds in controlled growth experiments, we show here that the low C transfer efficiency of coccal and filamentous cyanobacteria to the keystone herbivore Daphnia is caused by the low sterol content in cyanobacteria, which constrains cholesterol synthesis and thereby growth and reproduction of the herbivore. Estimations of sterol requirement in Daphnia suggest that, when cyanobacteria comprise more than 80% of the grazed phytoplankton, growth of the herbivore may be limited by sterols and Daphnia may subsequently fail to control phytoplankton biomass. Dietary sterols therefore may play a key role in freshwater food webs and in the control of water quality in lakes dominated by cyanobacteria.

Microfluidic systems in proteomics.

Abstract: We present the state-of-the-art in miniaturized sample preparation, immunoassays, one-dimensional and multidimensional analyte separations, and coupling of microdevices with electrospray ionization-mass spectrometry Hyphenation of these different techniques and their relevance to proteomics will be discussed In particular, we will show that analytical performances of microfluidic analytical systems are already close to fulfill the requirements for proteomics, and that miniaturization results at the same time in a dramatic increase in analysis throughput Throughout this review, some examples of analytical operations that cannot be achieved without microfluidics will be emphasized Finally, conditions for the spreading of microanalytical systems in routine proteomic labs will be discussed

Rust haustoria : nutrient uptake and beyond

Abstract: Haustoria are morphological features of an extremely successful class of plant parasites, the obligate biotrophs. The broad phylogenetic spectrum of organisms producing haustoria suggests that these structures have arisen many times in the course of evolution and represent specific adaptations of these organisms to the close interaction with their respective host plants. This close interaction and the fact that these structures cannot be produced in vitro have hampered an analysis of the roles of haustoria in biotrophy for many decades. Only recently has it become possible to analyse haustorial function at a molecular level. A picture is beginning to emerge indicating that haustoria do not only serve in nutrient uptake - a task postulated for these elements ever since their discovery. Moreover, they seem to perform enormous biosynthetic duties. They also seem to be engaged in the suppression of host defense responses and in redirecting or reprogramming the host's metabolic flow. This review intends to summarize current knowledge about the structure and function especially of rust haustoria.

Modern Michelson-Morley experiment using cryogenic optical resonators.

Abstract: We report on a new test of Lorentz invariance performed by comparing the resonance frequencies of two orthogonal cryogenic optical resonators subject to Earth's rotation over $\ensuremath{\sim}1\text{ }\mathrm{y}\mathrm{r}$. For a possible anisotropy of the speed of light $c$, we obtain ${\ensuremath{\Delta}}_{\ensuremath{\theta}}c/{c}_{0}=(2.6\ifmmode\pm\else\textpm\fi{}1.7)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}15}$. Within the Robertson-Mansouri-Sexl (RMS) test theory, this implies an isotropy violation parameter $\ensuremath{\beta}\ensuremath{-}\ensuremath{\delta}\ensuremath{-}\frac{1}{2}=(\ensuremath{-}2.2\ifmmode\pm\else\textpm\fi{}1.5)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}9}$, about 3 times lower than the best previous result. Within the general extension of the standard model of particle physics, we extract limits on seven parameters at accuracies down to ${10}^{\ensuremath{-}15}$, improving the best previous result by about 2 orders of magnitude.

Democracy, government spending, and economic growth: A political-economic explanation of the Barro-effect

Abstract: The paper develops a political economicargument for the recently observed inverseu-shaped relation between the level ofdemocracy and economic performance. A modelis constructed that shows why and howpolitical participation influences thespending behavior of opportunisticgovernments that can choose an optimalcombination of rents and public goods toattract political support. If the level ofdemocracy remains comparably low,governments rationally choose rents as aninstrument to assure political support.With increasing democratic participation,however, rents become an increasinglyexpensive instrument while the provision ofpublic goods becomes more and moreefficient in ensuring the incumbentgovernment's survival in power. As a consequence, an increase in democracy tends toraise growth rates of per capita income.However, the beneficial impact of democracyon growth holds true only for moderatedegrees of political participation. If –in semi-democratic countries – politicalparticipation increases further,governments have an incentive toover-invest in the provision of publicgoods. This model allows to derive and testthree hypothesis: Firstly, based on asimple endogenous growth model, weempirically substantiate our hypothesis ofa non-linear, inverse u-shaped relationbetween the level of democracy and growthof per capita income. Secondly, we showthat the impact of government spending oneconomic growth is higher in moredemocratic countries. Thirdly, wedemonstrate that the level of democracy andgovernment share of GDP are correlated in au-shaped manner.

Lipopolysaccharide (LPS)-binding protein mediates LPS detoxification by chylomicrons.

Abstract: Chylomicrons have been shown to protect against endotoxin-induced lethality. LPS-binding protein (LBP) is involved in the inactivation of bacterial toxin by lipoproteins. The current study examined the interaction among LBP, chylomicrons, and bacterial toxin. LBP was demonstrated to associate with chylomicrons and enhance the amount of LPS binding to chylomicrons in a dose-dependent fashion. In addition, LBP accelerated LPS binding to chylomicrons. This LBP-induced interaction of LPS with chylomicrons prevented endotoxin toxicity, as demonstrated by reduced cytokine secretion by PBMC. When postprandial circulating concentrations of chylomicrons were compared with circulating levels of low density lipoprotein, very low density lipoprotein, and high density lipoprotein, chylomicrons exceeded the other lipoproteins in LPS-inactivating capacity. Furthermore, highly purified lipoteichoic acid, an immunostimulatory component of Gram-positive bacteria, was detoxified by incubation with LBP and chylomicrons. In conclusion, our results indicate that LBP associates with chylomicrons and enables chylomicrons to rapidly bind bacterial toxin, thereby preventing cell activation. Besides a role in the detoxification of bacterial toxin present in the circulation, we believe that LBP-chylomicron complexes may be part of a local defense mechanism of the intestine against translocated bacterial toxin.

Microbial community structure in midgut and hindgut of the humus-feeding larva of Pachnoda ephippiata (Coleoptera: Scarabaeidae).

Abstract: The guts of soil-feeding macroinvertebrates contain a complex microbial community that is involved in the transformation of ingested soil organic matter. In a companion paper (T. Lemke, U. Stingl, M. Egert, M. W. Friedrich, and A. Brune, Appl. Environ. Microbiol. 69:6650-6658, 2003), we show that the gut of our model organism, the humivorous larva of the cetoniid beetle Pachnoda ephippiata, is characterized by strong midgut alkalinity, high concentrations of microbial fermentation products, and the presence of a diverse, yet unstudied microbial community. Here, we report on the community structure of bacteria and archaea in the midgut, hindgut, and food soil of P. ephippiata larvae, determined with cultivation-independent techniques. Clone libraries and terminal restriction fragment length polymorphism analysis of 16S rRNA genes revealed that the intestines of P. ephippiata larvae contain a complex gut microbiota that differs markedly between midgut and hindgut and that is clearly distinct from the microbiota in the food soil. The bacterial community is dominated by phylogenetic groups with a fermentative metabolism (Lactobacillales, Clostridiales, Bacillales, and Cytophaga-Flavobacterium-Bacteroides [CFB] phylum), which is corroborated by high lactate and acetate concentrations in the midgut and hindgut and by the large numbers of lactogenic and acetogenic bacteria in both gut compartments reported in the companion paper. Based on 16S rRNA gene frequencies, Actinobacteria dominate the alkaline midgut, while the hindgut is dominated by members of the CFB phylum. The archaeal community, however, is less diverse. 16S rRNA genes affiliated with mesophilic Crenarchaeota, probably stemming from the ingested soil, were most frequent in the midgut, whereas Methanobacteriaceae-related 16S rRNA genes were most frequent in the hindgut. These findings agree with the reported restriction of methanogenesis to the hindgut of Pachnoda larvae.

An improvement of rotation invariant 3D-shape based on functions on concentric spheres

Abstract: In this paper, we consider 3D-shape descriptors generated by using functions on a sphere. The descriptors are engaged for retrieving polygonal mesh models. Invariance of descriptors with respect to rotation of a model can be achieved either by using the principle component analysis (PCA) or defining features in which the invariance exists. The contribution of the paper is twofold: firstly, we define a new rotation invariant feature vector based on functions on concentric spheres, which outperforms a recently proposed descriptor; secondly, we compare the two approaches for achieving rotation invariance as well as options to use a single function or several functions on concentric spheres to generate feature vectors. We conclude that descriptors, which use the PCA, outperform others, while capturing the internal structure of a 3D-model with functions on concentric spheres can improve retrieval effectiveness.

Closing of the Tethys Sea and the phylogeny of Eurasian killifishes (Cyprinodontiformes: Cyprinodontidae).

Abstract: To test vicariant speciation hypotheses derived from geological evidence of the closing of the Tethys Sea, we reconstruct phylogenetic relationships of the predominantly fresh-water killifish genus Aphanius using 3263 aligned base pairs of mitochondrial DNA from samples representing 49 populations of 13 species. We use additional 11 cyprinodontid species as outgroup taxa. Genes analysed include those encoding the partial 12S and 16S ribosomal RNAs; transfer RNAs for valine, leucine, isoleucine, glutamine, methionine, tryptophan, alanine, asparagine, cysteine and tyrosine; and complete nicotinamide adenine dinucleotide dehydrogenase subunit I and II. Molecular substitution rate for this DNA region is estimated at of 8.6 +/- 0.1 x 10(-9) substitutions base pair(-1) year(-1), and is derived from a well dated transgression of the Red Sea into the Wadi Sirhan of Jordan 13 million years ago; an alternate substitution rate of 1.1 +/- 0.2 x 10(-8) substitutions base pair(-1) year(-1) is estimated from fossil evidence. Aphanius forms two major clades which correspond to the former eastern and western Tethys Sea. Within the eastern clade Oligocene divergence into a fresh-water clade inhabiting the Arabian Peninsula and an euhaline clade inhabiting coastal area from Pakistan to Somalia is observed. Within the western Tethys Sea clade we observe a middle Oligocene divergence into Iberian Peninsula and Atlas Mountains, and Turkey and Iran sections. Within Turkey we observe a large amount of genetic differentiation correlated with late Miocene orogenic events. Based on concordance of patterns of phylogenetic relationships and area relationships derived from geological and fossil data, as well as temporal congruence of these patterns, we support a predominantly vicariant-based speciation hypothesis for the genus Aphanius. An exception to this pattern forms the main clade of A. fasciatus, an euhaline circum-Mediterranean species, which shows little genetic differentiation or population structuring, thus providing no support for the hypothesis of vicariant differentiation associated with the Messinian Salinity Crisis. The two phylogenetically deepest events were also likely driven by ecological changes associated with the closing of the Tethys Sea.