Showing papers by "University of Konstanz published in 2002"

Lateral relocation of auxin efflux regulator PIN3 mediates tropism in Arabidopsis

Abstract: Long-standing models propose that plant growth responses to light or gravity are mediated by asymmetric distribution of the phytohormone auxin. Physiological studies implicated a specific transport system that relocates auxin laterally, thereby effecting differential growth; however, neither the molecular components of this system nor the cellular mechanism of auxin redistribution on light or gravity perception have been identified. Here, we show that auxin accumulates asymmetrically during differential growth in an efflux-dependent manner. Mutations in the Arabidopsis gene PIN3, a regulator of auxin efflux, alter differential growth. PIN3 is expressed in gravity-sensing tissues, with PIN3 protein accumulating predominantly at the lateral cell surface. PIN3 localizes to the plasma membrane and to vesicles that cycle in an actin-dependent manner. In the root columella, PIN3 is positioned symmetrically at the plasma membrane but rapidly relocalizes laterally on gravity stimulation. Our data indicate that PIN3 is a component of the lateral auxin transport system regulating tropic growth. In addition, actin-dependent relocalization of PIN3 in response to gravity provides a mechanism for redirecting auxin flux to trigger asymmetric growth.

Why Social Preferences Matter - The Impact of Non-Selfish Motives on Competition, Cooperation and Incentives

Abstract: A substantial number of people exhibit social preferences, which means they are not solely motivated by material self-interest but also care positively or negatively for the material payoffs of relevant reference agents. We show empirically that economists fail to understand fundamental economic questions when they disregard social preferences, in particular, that without taking social preferences into account, it is not possible to understand adequately (i) effects of competition on market outcomes, (ii) laws governing cooperation and collective action, (iii) effects and the determinants of material incentives, (iv) which contracts and property rights arrangements are optimal, and (v) important forces shaping social norms and market failures.

Shape analysis of symmetric structures: quantifying variation among individuals and asymmetry.

Abstract: Morphometric studies often consider parts with internal left-right symmetry, for instance, the vertebrate skull. This type of symmetry is called object symmetry and is distinguished from matching symmetry, in which two separate structures exist as mirror images of each other, one on each body side. We explain a method for partitioning the total shape variation of landmark configurations with object symmetry into components of symmetric variation among individuals and asymmetry. This method is based on the Procrustes superimposition of the original and a reflected copy of each landmark configuration and is compatible with the two-factor ANOVA model customary in studies of fluctuating asymmetry. We show a fully multivariate framework for testing the effects in the two-factor model with MANOVA statistics, which also applies to shapes with matching symmetry. We apply the new methods in a small case study of pharyngeal jaws of the Neotropical cichlid fish Amphilophus citrinellus. The analysis revealed that the symmetric component of variation in the pharyngeal jaws is dominated by the contrast between two alternative trophic morphs in this species and that there is subtle but statistically significant directional asymmetry. Finally, we provide some general recommendations for morphometric studies of symmetric shapes.

Large‐scale neural correlates of affective picture processing

Abstract: Hemodynamic and electrophysiological studies indicate differential brain response to emotionally arousing, compared to neutral, pictures. The time course and source distribution of electrocortical potentials in response to emotional stimuli, using a high-density electrode (129-sensor) array were examined here. Event-related potentials (ERPs) were recorded while participants viewed pleasant, neutral, and unpleasant pictures. ERP voltages were examined in six time intervals, roughly corresponding to P1, N1, early P3, late P3 and a slow wave window. Differential activity was found for emotional, compared to neutral, pictures at both of the P3 intervals, as well as enhancement of later posterior positivity. Source space projection was performed using a minimum norm procedure that estimates the source currents generating the extracranially measured electrical gradient. Sources of slow wave modulation were located in occipital and posterior parietal cortex, with a right-hemispheric dominance.

‚The Good, the Bad, and the Ugly‘

Abstract: Folgt man dem einflussreichsten Beitrag zur vergleichenden Wohlfahrtsstaatsforschung der letzten Zeit, Esping-Andersens „Three Worlds of Welfare Capitalism“, so tritt der entwickelte westliche Sozialstaat in drei Varianten auf: entweder als sozialdemokratisches, als konservatives oder als liberales Wohlfahrtsstaatsregime. Ein genauerer Blick zeigt, dass Esping-Andersens Typenbildung und Landerzuordnungen insbesondere im Fall des konservativen Regimes sehr problematisch sind. Der Beitrag argumentiert, dass diese gravierenden Probleme daher ruhren, dass seine Theorie vornehmlich den Klassenkonflikt, nur selektiv aber den Einfluss konfessioneller Faktoren in den Blick nimmt. Wesentliche theoretische Widerspruche und empirische Unstimmigkeiten seines Ansatzes lassen sich losen, wenn man neben der Bedeutung der katholischen Soziallehre fur den institutionellen Entwicklungspfad des Sozialstaats auch den Einfluss des Protestantismus, und hier insbesondere den Einfluss der freikirchlichen Stromungen des Protestantismus und des Calvinismus beachtet. Der Beitrag zeigt dies mit vergleichenden Daten sowohl fur die Fruhphase (1890 bis 1920), als auch fur die Hochzeit des entwickelten Wohlfahrtsstaats (von 1960 bis 1990).

New treatments in neurorehabilitation founded on basic research

Abstract: Recent discoveries about how the central nervous system responds to injury and how patients reacquire lost behaviours by training have yielded promising new therapies for neurorehabilitation. Until recently, this field had been largely static, but the current melding of basic behavioural science with neuroscience promises entirely new approaches to improving behavioural, perceptual and cognitive capabilities after neurological damage. Studies of phenomena such as cortical reorganization after a lesion, central nervous system repair, and the substantial enhancement of extremity use and linguistic function by behavioural therapy, support this emerging view. The ongoing changes in rehabilitation strategies might well amount to an impending paradigm shift in this field.

Accelerating XPath location steps

Abstract: This work is a proposal for a database index structure that has been specifically designed to support the evaluation of XPath queries. As such, the index is capable to support all XPath axes (including ancestor, following, preceding-sibling, descendant-or-self, etc.). This feature lets the index stand out among related work on XML indexing structures which had a focus on regular path expressions (which correspond to the XPath axes children and descendant-or-self plus name tests). Its ability to start traversals from arbitrary context nodes in an XML document additionally enables the index to support the evaluation of path traversals embedded in XQuery expressions. Despite its flexibility, the new index can be implemented and queried using purely relational techniques, but it performs especially well if the underlying database host provides support for R-trees. A performance assessment which shows quite promising results completes this proposal.

Therapeutically effective antibodies against amyloid-β peptide target amyloid-β residues 4−10 and inhibit cytotoxicity and fibrillogenesis

Abstract: Immunization of transgenic mouse models of Alzheimer disease using amyloid-beta peptide (Abeta) reduces both the Alzheimer disease-like neuropathology and the spatial memory impairments of these mice. However, a therapeutic trial of immunization with Abeta42 in humans was discontinued because a few patients developed significant meningo-encephalitic cellular inflammatory reactions. Here we show that beneficial effects in mice arise from antibodies selectively directed against residues 4-10 of Abeta42, and that these antibodies inhibit both Abeta fibrillogenesis and cytotoxicity without eliciting an inflammatory response. These findings provide the basis for improved immunization antigens as well as attempts to design small-molecule mimics as alternative therapies.

Do civil and political repression really boost foreign direct investments

Abstract: Multinational enterprises are often accused of having a preference for investing in countries in which the working populations' civil and political rights are largely disregarded. This article presents an empirical investigation of the popular “political repression boosts FDI” hypothesis and arrives at the conclusion that the hypothesis is not supported. On the contrary, multinational enterprises rather appear to be attracted by countries in which civil and political freedom is respected.

Nanometer resolution and coherent optical dipole coupling of two individual molecules.

Abstract: By performing cryogenic laser spectroscopy under a scanning probe electrode that induces a local electric field, we have resolved two individual fluorescent molecules separated by 12 nanometers in an organic crystal. The two molecules undergo a strong coherent dipole-dipole coupling that produces entangled sub- and superradiant states. Under intense laser illumination, both molecules are excited via a two-photon transition, and the fluorescence from this doubly excited system displays photon bunching. Our experimental scheme can be used to optically resolve molecules at the nanometer scale and to manipulate the degree of entanglement among them.

Synergistic interactions in the microbial world

Abstract: After several decades of microbiological research has focused on pure cultures, synergistic effects between different types of microorganisms find increasing interest. Interspecies interactions between prokaryotic cells have been studied into depth mainly with respect to syntrophic cooperations involved in methanogenic degradation of electron-rich substrates such as fatty acids, alcohols, and aromatics. Partners involved in these processes have to run their metabolism at minimal energy increments, with only fractions of an ATP unit synthesized per substrate molecule metabolized, and their cooperation is intensified by close proximity of the partner cells. New examples of such syntrophic activities are anaerobic methane oxidation by presumably methanogenic and sulfate-reducing prokaryotes, and microbially mediated pyrite formation. Syntrophic relationships have also been discovered to be involved in the anaerobic metabolization of amino acids and sugars where energetical restrictions do not necessarily force the partner organisms into strict interdependencies. The most highly developed cooperative systems among prokaryotic cells appear to be the structurally organized phototrophic consortia of the Chlorochromatium and Pelochromatium type in which phototrophic and chemotrophic bacteria not only exchange metabolites but also interact at the level of growth coordination and tactic behaviour.

Cleavage of plasma membrane calcium pumps by caspases: a link between apoptosis and necrosis

Abstract: Neuronal death, which follows ischemic injury or is triggered by excitotoxins, can occur by both apoptosis and necrosis. Caspases, which are not directly required for necrotic cell death, are central mediators of the apoptotic program. Here we demonstrate that caspases cleave and inactivate the plasma membrane Ca2+ pump (PMCA) in neurons and non-neuronal cells undergoing apoptosis. PMCA cleavage impairs intracellular Ca2+ handling, which results in Ca2+ overload. Expression of non-cleavable PMCA mutants prevents the disturbance in Ca2+ handling, slows down the kinetics of apoptosis, and markedly delays secondary cell lysis (necrosis). These findings suggest that caspase-mediated cleavage and inactivation of PMCAs can lead to necrosis, an event that is reduced by caspase inhibitors in brain ischemia.

Phylogeny of the Lake Tanganyika Cichlid Species Flock and Its Relationship to the Central and East African Haplochromine Cichlid Fish Faunas

Abstract: Lake Tanganyika, the oldest of the East African Great Lakes, harbors the ecologically, mor- phologically, and behaviorally most complex of all assemblages of cichlid eshes, consisting of about 200 described species. The evolutionary old age of the cichlid assemblage, its extreme degree of mor- phological differentiation, the lack of species with intermediate morphologies, and the rapidity of lineage formation have made evolutionary reconstruction difecult. The number and origin of seeding lineages, particularly the possible contribution of riverine haplochromine cichlids to endemic lacus- trine lineages, remains unclear. Our phylogenetic analyses, based on mitochondrial DNA sequences of three gene segments of 49 species (25% of all described species, up to 2,400 bp each), yield ro- bust phylogenies that provide new insights into the Lake Tanganyika adaptive radiation as well as into the origin of the Central- and East-African haplochromine faunas. Our data suggest that eight ancientAfrican lineages may haveseededthe Tanganyikan cichlid radiation.Oneof theseseeding lin- eages, probably comprising substrate spawning Lamprologus-like species, diversieed into six lineages that evolved mouthbrooding during the initial stage of the radiation. All analyzed haplochromines from surrounding rivers and lakes seem to have evolved within the radiating Tanganyikan lineages. Thus, our endingscontradictthe current hypothesis thatancestralriverinehaplochrominescolonized Lake Tanganyika to give rise to at least part of its spectacular endemic cichlid species assemblage. Instead, the early phases of the Tanganyikan radiation affected Central and East African rivers and lakes. The haplochromines may have evolved in the Tanganyikan basin before the lake became a hydrologically and ecologically closed system and then secondarily colonized surrounding rivers. Apparently, therefore, the current diversity of Central and East African haplochromines represents a relatively young and polyphyletic fauna that evolved from or in parallel to lineages now endemic to Lake Tanganyika. (Adaptive radiation; Cichlidae; Lake Tanganyika; mitochondrial DNA sequences; molecular phylogeny; species eock.)

Synthetic lipoteichoic acid from Staphylococcus aureus is a potent stimulus of cytokine release

Abstract: We recently purified lipoteichoic acid (LTA) from Staphylococcus aureus to more than 99% purity by a novel preparation method and deduced its structure with the first nuclear magnetic resonance (NMR) of a complete LTA. In contrast to Gram-negative lipopolysaccharides, this LTA requires the toll-like receptor (TLR)-2 and not TLR-4 for cytokine induction in monocytes and macrophages. To elucidate the structure‐function relationships for LTA from S. aureus , the lipid anchor was prepared by either acidic hydrolysis of native LTA or chemical synthesis (gentiobiosyl- sn -dimyristoylglycerol). Next, a complete LTA molecule with six glycerophosphate units carrying four alanine plus one N -acetyl-glucosamine substituent was synthesized, which displayed the same potency to activate monocytes as native LTA. However, 100‐1,000 times higher concentrations of the lipid anchor were required for cytokine induction. It is worthy to note that replacing d -alanine with l -alanine blunted the effect indicating stereoselective recognition. The structure identification of this synthesized and biologically active LTA was proven by NMR and matrix-assisted laser desorption-ionization mass spectrometry. We concluded that the lipid anchor, with its fatty acids, represents an integral part of the immunostimulatory activity of LTA, but requires additional structural components on the polyglycerophosphate backbone.

Structure of Human Cd1B with Bound Ligands at 2.3 A, a Maze for Alkyl Chains

Abstract: The human genome encodes five nonpolymorphic major histocompatibility complex class I-like glycoproteins, CD1a to CD1e, that present lipid antigens for specific recognition by T lymphocytes. Using single alkyl chain detergents, we developed a protocol to generate recombinant human CD1b-lipid complexes. We present here the crystal structures of CD1b in complex with either phosphatidylinositol or ganglioside GM2 at 2.3 A and 2.8 A resolutions, respectively. The antigen-binding groove houses four interlinked hydrophobic channels that are occupied by the alkyl chains of the glycolipid plus two detergent molecules. A distinct exit beneath the alpha 2 helix further contributes to the plasticity of the binding groove. These structures reveal the mechanism by which two alkyl chain lipids bind to CD1b, and how CD1b can adapt to ligands of different alkyl chain length. They also suggest how very long alkyl chains, such as those of mycolic acid, could be fully contained within the binding groove. These results extend the spectrum of potential CD1b ligands by revealing that, in addition to two alkyl chain lipids, mono-alkyl and triple-alkyl chain lipids can be accommodated in the binding groove.

Polyphenolic allelochemicals from the aquatic angiosperm Myriophyllum spicatum inhibit photosystem II.

Abstract: Myriophyllum spicatum (Haloragaceae) is a highly competitive freshwater macrophyte that produces and releases algicidal and cyanobactericidal polyphenols. Among them, beta-1,2,3-tri-O-galloyl-4,6-(S)-hexahydroxydiphenoyl-D-glucose (tellimagrandin II) is the major active substance and is an effective inhibitor of microalgal exoenzymes. However, this mode of action does not fully explain the strong allelopathic activity observed in bioassays. Lipophilic extracts of M. spicatum inhibit photosynthetic oxygen evolution of intact cyanobacteria and other photoautotrophs. Fractionation of the extract provided evidence for tellimagrandin II as the active compound. Separate measurements of photosystem I and II activity with spinach (Spinacia oleracea) thylakoid membranes indicated that the site of inhibition is located at photosystem II (PSII). In thermoluminescence measurements with thylakoid membranes and PSII-enriched membrane fragments M. spicatum extracts shifted the maximum temperature of the B-band (S(2)Q(B)(-) recombination) to higher temperatures. Purified tellimagrandin II in concentrations as low as 3 microM caused a comparable shift of the B-band. This demonstrates that the target site of this inhibitor is different from the Q(B)-binding site, a common target of commercial herbicides like 3-(3,4-dichlorophenyl)-1,1-dimethylurea. Measurements with electron paramagnetic resonance spectroscopy suggest a higher redox midpoint potential for the non-heme iron, located between the primary and the secondary quinone electron acceptors, Q(A) and Q(B). Thus, tellimagrandin II has at least two modes of action, inhibition of exoenzymes and inhibition of PSII. Multiple target sites are a common characteristic of many potent allelochemicals.

Intergenerational Ambivalence: Further Steps in Theory and Research

Abstract: Key Words: ambivalence, family therapy, gender, intergenerational relations, postmodernism. The article by Ingrid Connidis and Julie McMullin and the initiative of the Journal of Marriage and Family's editor provide an excellent opportunity to continue the discussion on the relevance of the concept of ambivalence for the study of intergenerational relations. Nearly 4 years have passed since Karl Pillemer and I (Luscher & Pillemer, 1998) published our ideas on the topic in this journal. Connidis and McMullin take this article as their starting point and refer to it both approvingly and critically. I cannot always follow their critique, as I will show at appropriate points below. What counts most, however (and this is greatly to be applauded) is that all of us are interested in the further development of the approach. Interestingly, insights into the ambivalence between parents and adult children can be traced back to the beginnings of human society, although the term itself was apparently first created only in 1910. In Greek mythology, some of the greatest sagas depict what we now refer to as ambivalence. The best known of these is the drama of the fateful relationship between Oedipus and his father. This theme is also found in modern literature. Franz Kafka's story The Metamorphosis or, more recently, Philip Roth's novel American Pastoral, are only two of many examples. Today, the term ambivalence is widely used. For example, we may hear adult children saying that they feel ambivalent about placing their elderly father or mother in a nursing home. The central question, then, is to determine what can be gained by using the concept in family research. I agree with Connidis and McMullin that the concept of ambivalence enables us to study intergenerational relationships with greater openness and it can help to accentuate the sociological perspective. To this end, the structural conditions of ambivalence should be given adequate attention. The authors mention gender inequality as a particular example, thereby providing a bridge to gender studies. Taking this a step further, I see the concept of ambivalence as well-suited to linking various disciplines that work on the "problem of generations" (Mannheim, 1928). Ambivalence can be comprehended as a "sensitizing concept," as defined by Blumer (1969), giving "the user a general sense of reference and guidance in approaching empirical instances. Whereas definitive concepts provide prescriptions of what to see, sensitizing concepts merely suggest directions along which to look." (p. 148). I would even maintain that the challenge of ambivalence lies in its ambiguities. I say this drawing on Levine's stimulating book, The Flight from Ambiguity (1986). The author provides a wellgrounded argument that insight into the ambiguity of a concept is a motor for the development of new ideas. But in order for this motor to really function and propel us forward, conceptual determinations are indispensable. They are also the foundation for the formulation of specific hypotheses and for the development of research instruments. In this regard, few concrete suggestions can be found in the article by Connidis and McMullin. Of course they offer numerous examples but for research, systematic conceptual work is indispensable. This is where the scientific approach to intergenerational ambivalence differs from that found in literary works and everyday common sense. STEPS TOWARD DEFINING AMBIVALENCE In order to avoid a potential misunderstanding, I would like to make it clear that I do not intend to present an all-purpose or ultimate definition of ambivalence. That would be dogmatic. Because ambivalence is a concept that is discussed in many different contexts-from ordinary language to psychological and sociological research-we must attempt to isolate its major ideas and dimensions. For this purpose, it is most useful to turn to the brief yet many faceted history of the concept's scientific use. …

Quantum-optical catalysis: generating nonclassical states of light by means of linear optics.

Abstract: We report preparation and characterization of coherent superposition states t[0>+alpha]1> of the electromagnetic field by conditional measurements on a beam splitter. This state is generated in one of the beam splitter output channels if a coherent state [alpha> and a single-photon Fock state [1> are present in the two input ports and a single photon is registered in the other beam splitter output. The single photon thus plays a role of a "catalyst:" it is explicitly present in both the input and the output channels of the interaction yet facilitates generation of a nonclassical state of light.

Structural decomposition and heterogeneity of commercial lipoteichoic Acid preparations.

Abstract: Fractionation of commercial preparations of lipoteichoic acids (LTA) by hydrophobic interaction chromatography (HIC) and nuclear magnetic resonance spectroscopy revealed very inhomogeneous compositions and decomposition of the LTA structure: LTA content of the preparations averaged 61% for Streptococcus pyogenes, 16% for Bacillus subtilis, and 75% for Staphylococcus aureus. The decomposition was characterized by a loss of glycerophosphate units as well as alanine and N-acetylglucosamine substituents. All preparations contained—to varying degrees—non-LTA, non-lipopolysaccharide (LPS) immunostimulatory components as indicated by their elution profile in HIC, lack of phosphate, and negative Limulus amoebocyte lysate (LAL) test results. After purification, the commercial LTA from Bacillus subtilis and S. pyogenes but not LTA from S. aureus induced the release of tumor necrosis factor alpha, interleukin 1 beta (IL-1β), IL-6, and IL-10 in human blood. While pure LTA are negative in the LAL assay, endotoxin equivalents of more than 10 ng of LPS/mg of LTA were found in the commercial preparations. Taken together, these data indicate that these crude preparations with relatively high endotoxin contamination are not suitable for characterizing the activation of immune cells by LTA.

Expansion of the tonotopic area in the auditory cortex of the blind

Abstract: A part of the core area of the auditory cortex was examined in nine blind and10 sighted individuals by magnetic source imaging and was found to be enlarged by a factor of 1.8 in the blind compared with the sighted humans. Moreover, the latency of the N1m component of the auditory-evoked magnetic response was significantly decreased in the blind. The development of use-dependent cortical reorganization may be a consequence of the absence of visual input in combination with enhanced auditory activity generated by the long-term concentration by blind individuals on nonvisual cues to interact appropriately with the environment. It is consistent with and well suited to mediate the demonstrated increased ability of the blind to accurately localize acoustic sources in peripheral auditory fields and to decode speech.

Phycodnaviridae--large DNA algal viruses.

Abstract: Members and prospective members of the family Phycodnaviridae are large icosahedral, dsDNA (180 to 560 kb) viruses that infect eukaryotic algae. The genomes of two phycodnaviruses have been sequenced: the 331 kb genome of Paramecium bursaria chlorella virus (PBCV-1) and more recently, the 336 kb genome of the Ectocarpus siliculosus virus (EsV-1). EsV-1 has ∼ 231 protein-encoding genes whereas, the slightly smaller PBCV-1 genome has 11 tRNA genes and ∼ 375 protein-encoding genes. Surprisingly, the two viruses only have 33 genes in common, of which 17 have no counterparts in the databases. The low number of homologous genes between the two viruses can probably be attributed to their different life styles. PBCV-1 is a lytic virus that infects a unicellular, endosymbiotic freshwater green alga whereas, EsV-1 is a lysogenic virus that infects a free-living filamentous marine brown alga. Furthermore, accumulating evidence indicates that the phycodnaviruses and their genes are ancient, thus allowing significant differences to have evolved. This review briefly describes some of the biological properties of the phycodnaviruses, focusing on PBCV-1 and EsV-1, and then compares their genomes.

The adaptive potential of skeletal muscle fibers.

Abstract: Mammalian skeletal muscle fibers display a great adaptive potential. This potential results from the ability of muscle fibers to adjust their molecular, functional, and metabolic properties in resp...

Energetics and kinetics of lactate fermentation to acetate and propionate via methylmalonyl-CoA or acrylyl-CoA

Abstract: Fermentation balances and growth yields were determined with various bacteria fermenting lactate to acetate plus propionate either via methylmalonyl-CoA or via acrylyl-CoA. All strains fermented lactate to acetate plus propionate at approximately a 1:2 ratio. Growth yields of Propionibacterium freudenreichii were more than twice as high as those of Clostridium homopropionicum or Veillonella parvula. Hydrogen was formed as a side product to a significant extent only by V. parvula and Pelobacter propionicus; the latter formed hydrogen preferentially when using ethanol as substrate. Acrylyl-CoA reductase of C. homopropionicum and Clostridium neopropionicum was found nearly exclusively in the cytoplasm thus confirming that this reduction step is unlikely to be involved in energy conservation. C. homopropionicum exhibited higher KS and higher μmax values, as well as higher specific substrate turnover rates than P. freudenreichii. The results allow us to conclude that C. homopropionicum using the acrylyl-CoA pathway with low growth yield obtains its specific competitive advantage compared to P. freudenreichii not through higher substrate affinity or metabolic shift toward enhanced acetate-plus-hydrogen formation but through faster specific substrate turnover.

In vivo characterization of diatom multipartite plastid targeting signals

Abstract: Plastids of diatoms and related algae are delineated by four membranes: the outermost membrane (CER) is continuous with the endoplasmic reticulum while the inner two membranes are homologous to plastid envelope membranes of vascular plants and green algae. Proteins are transported into these plastids by pre-sequences that have two recognizable domains. To characterize targeting of polypeptides within diatom cells, we generated constructs encoding green fluorecent protein (GFP) fused to leader sequences. A fusion of GFP to the pre-sequence of BiP [an endoplasmic reticulum (ER)-localized chaperone] resulted in accumulation of GFP within the ER; a construct encoding the pre-sequence of a plastid protein fused to GFP was directed into the plastids. Additional constructs demonstrated that the N-terminal region of the bipartite plastid targeting pre-sequence was necessary for transport of polypeptides to the lumen of the ER, while the C-terminal region was shown to enable the proteins to traverse the plastid double envelope membrane. Our data strongly support the hypothesis of a multi-step plastid targeting process in chromophytic algae and raises questions about the continuity of the ER and CER and the function of the latter in polypeptide trafficking.

Urine makes the difference: chemical communication in fighting crayfish made visible.

Abstract: Chemical communication is a widespread phenomenon in aquatic animals but is difficult to investigate because the signals are not visible. Here, we present the results of a study into chemical communication in blindfolded fighting crayfish (Astacus leptodactylus) in which we employed a new method: visualisation of urine using the dye Fluorescein. The probability of urine release is greater during fights than during non-social activities or inactivity. The eventual winners are more likely to release urine during fights than the eventual losers. In both winners and losers, urine release is coupled to offensive behaviours, and the probability of urine release increases with increasing levels of aggression. In A. leptodactylus, urine is carried to the opponent by the forward-projecting gill currents. During spontaneous release, urine is fanned laterally with the aid of the exopodites of the maxillipeds. Aggressive behaviour is effective in intimidating blindfolded opponents only in conjunction with urine release: receivers decrease offensive behaviour and increase defensive behaviour. Aggressive behaviour alone does not intimidate opponents. The loser of a recent fight is deterred equally well by a familiar and an unfamiliar opponent. Hence, in crayfish, individual recognition of the urine scent of a dominant individual does not appear to be significant for the maintenance of dominance hierarchies. Our results suggest that urine contains information about the fighting ability and/or aggressiveness of the signaller. The chemical signals thus far unidentified appear to be important in determining the outcome of a fight.

Eradication of Glioblastoma, and Breast and Colon Carcinoma Xenografts by Hsp70 Depletion

Abstract: Heat shock protein 70 (Hsp70) is an antiapoptotic chaperone protein highly expressed in human tumors. Here we demonstrate that locoregional application of adenovirus expressing antisense Hsp70 cDNA (Ad.asHsp70) eradicates orthotopic xenografts of glioblastoma and breast carcinoma, as well as s.c. xenografts of colon carcinoma in immunodeficient mice. Ad.asHsp70-treated tumors showed massive apoptosis-like cell death and recruitment of macrophages. Human monocyte-derived macrophages effectively removed the corpses of Ad.asHsp70-treated tumor cells in vitro. Interestingly, both tumor cell death and phagocytosis were caspase-independent. Thus, Hsp70 appears as a promising target for the treatment of cancers resistant to classic caspase-mediated apoptosis.

Thermoelasticity with second sound—exponential stability in linear and non‐linear 1‐d

Abstract: We consider linear and non-linear thermoelastic systems in one space dimension where thermal disturbances are modelled propagating as wave-like pulses travelling at finite speed. This removal of the physical paradox of infinite propagation speed in the classical theory of thermoelasticity within Fourier's law is achieved using Cattaneo's law for heat conduction. For different boundary conditions, in particular for those arising in pulsed laser heating of solids, the exponential stability of the now purely, but slightly damped, hyperbolic linear system is proved. A comparison with classical hyperbolic–parabolic thermoelasticity is given. For Dirichlet type boundary conditions—rigidly clamped, constant temperature—the global existence of small, smooth solutions and the exponential stability are proved for a non-linear system. Copyright © 2002 John Wiley & Sons, Ltd.