Showing papers by "Bielefeld University published in 1995"

The blue light-responsive AthH2 gene of Arabidopsis thaliana is primarily expressed in expanding as well as in differentiating cells and encodes a putative channel protein of the plasmalemma.

Abstract: According to our previous studies the Arabidopsis gene AthH2 which is inducible by blue light and phytohormones codes for an intrinsic membrane protein. It bears a resemblance to several distinct channel proteins of plant and animal species classified as the MIP/NOD-26/GlpF family. In the present study biochemical analyses and electron microscopic immunochemistry were used to elucidate the subcellular location of the AthH2 protein. The results clearly demonstrate that it is an exclusive constituent of the plasmalemma. Furthermore, the expression of the AthH2 gene in transgenic Arabidopsis plants containing the promoter region of AthH2 fused to the beta-glucuronidase (gus) reporter gene was studied. The in situ localization of gus activity revealed that the specific promoter is temporally activated by light in expanding and/or differentiating cells comprising newly formed tissues and organs: root elongation zone, guard cells of stomata, vascular bundle sheaths, filaments of stamen and young siliques. Several sites of gus expression coincide spatially with those of in situ hybridization and the immunocytochemical reaction, respectively, suggesting that the AthH2 promoter had correctly responded to light as an important exogenous factor with relevance to the complex pattern of differentiation. Studies with protoplasts from plants transformed with an antisense construct revealed a water transport capacity of the AthH2 protein.

Quarkonium production in hadronic collisions

Abstract: We summarize the theoretical description of charmonium and bottonium production in hadronic collisions and compare it to the available data from hadron-nucleon interactions. With the parameters of the theory established by these data, we obtain predictions for quarkonium production at RHIC and LHC energies.

Experimental Studies and Theoretical Predictions for the H + D2 → > HD + D Reaction

Abstract: The H + H2 exchange reaction constitutes an excellent benchmark with which to test dynamical theories against experiments. The H + D2 (vibrational quantum number v = 0, rotational quantum number j = 0) reaction has been studied in crossed molecular beams at a collision energy of 1.28 electron volts, with the use of the technique of Rydberg atom time-of-flight spectroscopy. The experimental resolution achieved permits the determination of fully rovibrational state-resolved differential cross sections. The high-resolution data allow a detailed assessment of the applicability and quality of quasi-classical trajectory (QCT) and quantum mechanical (QM) calculations. The experimental results are in excellent agreement with the QM results and in slightly worse agreement with the QCT results. This theoretical reproduction of the experimental data was achieved without explicit consideration of geometric phase effects.

Observable Attributesas Manifestations and Cues ofPersonality and Intelligence

Abstract: In this study, we investigated the relationship of participants' observable attributes to measures of their personality and intelligence; we also studied the ways in which strangers formed their perception of participants' personalities and intelligence. Fifty pairs of intimate acquaintances were videotaped in a standard situation, were administered an intelligence test, and provided self-reports of their personality and descriptions of their partner's personality. In addition, various observable attributes (such as hair color, stature, physical mannerisms) of the targets were measured. Strangers watched the videotapes and rated either the observable attributes or the personality traits of the targets. The observable attributes were then correlated with the personality measures and the intelligence and trait inferences by strangers. Extraversion was the trait with the most external manifestations and the strongest match between cue utilization and cue validity. Intelligence was inferred from visual as well as from acoustic attributes, but only acoustic cues mediated the correlation between psychometric intelligence and perceptions of intelligence by strangers.

Equation of State for the SU(3) Gauge Theory.

Abstract: By investigating the SU(3) gauge theory thermodynamics on lattices of various sizes we can control finite lattice cutoff effects. We calculate the pressure and energy density on lattices with temporal extent {ital N}{sub {tau}}=4, 6, and 8 and spatial extent {ital N}{sub {sigma}}=16 and 32, and extrapolate to the continuum limit. We find a deviation from ideal gas behavior of (15--20)%, even at temperatures as high as {ital T}{similar_to}3{ital T}{sub {ital c}}. A calculation of the critical temperature for {ital N}{sub {tau}}=8 and 12 and the string tension for {ital N}{sub {tau}}=32 is performed to fix the temperature scale, yielding {ital T}{sub {ital c}}/{radical}{sigma}=0.629(3) in the continuum limit. {copyright} {ital 1995} {ital The} {ital American} {ital Physical} {ital Society}.

Quarkonium production in hadronic collisions

Abstract: We summarize the theoretical description of charmonium and bottonium production in hadronic collisions and compare it to the available data from hadron-nucleon interactions. With the parameters of the theory established by these data, we obtain predictions for quarkonium production at RHIC and LHC energies.

Sensitivity of the mystacial vibrissae of harbour seals (Phoca vitulina) for size differences of actively touched objects.

Abstract: We studied the capability of one male and one female harbour seal Phoca vitulina to discriminate diameter differences of circular discs by means of active touch with their mystacial vibrissae. To prevent the animals from perceiving visual information, they were blindfolded during trials. In a two-alternative forced-choice procedure, the seals were required to choose the larger of two Perspex discs. Weber fractions c (the ratio of the lowest diameter difference detected by the seals on 75% of occasions to the starting disc diameter D, delta D/D = c) were determined for three standard discs (diameters 1.12cm, 5.04cm and 8.74cm) by the psychophysical method of limits. While the seals achieved Weber fractions of 0.29 (male) and 0.26 (female) at the smallest standard disc, their performance improved with increasing disc size, resulting in an approximately constant Weber fraction of 0.13 (male) and 0.08 (female) for the two larger standard discs. The difference in performance between the two seals did not reflect a real difference in sensitivity, but may best be explained by a difference in choice behaviour. As a measure of tactile acuity, the Weber fractions obtained for the larger standard discs indicate that harbour seals can use their mystacial vibrissae as efficiently for active touch as monkeys use their hands.

Molecular analysis of the Rhizobium meliloti mucR gene regulating the biosynthesis of the exopolysaccharides succinoglycan and galactoglucan.

Abstract: The Rhizobium meliloti Tn5 mutant Rm3131, producing galactoglucan (EPS II) instead of succinoglycan (EPS I), was complemented by a 3.6-kb EcoRI-fragment of the Rhizobium meliloti genome. Sequencing of this fragment revealed six open reading frames (ORFs). The ORF found to be affected in the mutant Rm3131 codes for a putative protein of 15.7 kDa and forms a monocistronic transcriptional unit. Further genetic analysis revealed that the gene mutated in Rm3131 is identical to the previously described R. meliloti mucR gene (H. Zhan, S. B. Levery, C. C. Lee, and J. A. Leigh, 1989, Proc. Natl. Acad. Sci. USA 86:3055-3059). By hybridization it was shown that a mucR homologous gene is present in several rhizobacteria. The deduced amino acid sequence of MucR showed nearly 80% identity to the Agrobacterium tumefaciens Ros protein, a negative regulator of vir genes and necessary for succinoglycan production. MucR contains like Ros a putative zinc finger sequence of the C2H2 type. Transcriptional fusions of genes for EPS I and EPS II synthesis, the so-called exo and exp genes, with the marker gene lacZ were used to delineate the role of mucR for exo and exp gene expression. It was found that exp genes are negatively regulated by MucR on the transcriptional level, whereas a posttranscriptional regulation by MucR is assumed for exo genes. Furthermore, mucR is negatively regulating its own transcription.

The effect of a masked stimulus on the response to the masking stimulus

Abstract: Four experiments are reported in which the subjects had to respond to a target that masked a preceding prime via metacontrast masking. In one part of Experiment l, the subjects discriminated the target's shape (square or diamond) by a motor-choice reaction, and in another part they had to respond with a simple reaction. The prime was neutral (circular) with respect to the target's shape. The data showed a facilitation effect. In both tasks the reaction time was reduced by the masked prime. However, the reduction was more pronounced with simple reaction than with choice reaction. In the other experiments, additional primes were used with the same angular shapes as the targets. In Experiments 2 and 3, after discriminating the target's shape by a choice reaction, the subjects had to judge the prime's shape in a signal-detection task. While neither the d' value for discriminating the angular primes from the circular ones (Exp. 2) nor the d' value for distinguishing between the angular primes (Exp. 3) was different from zero, the choice-reaction data showed a congruency effect. With a congruent prime (i.e., a prime that had the same shape as the target), the reaction times were reduced. With an incongruent prime, the reaction times grew. In Experiment 4 the errors were investigated. The facilitation effect was present in the RT, but not in the number of errors, whereas the congruency effect was present in the number, but not in the RT of errors. While the facilitation effect can be attributed either to an unspecific activation by the masked prime or to an influence of the prime on attentional processes, the congruency effect can be explained by the assumption that the masked prime directly activates the specific response, which corresponds to the prime's shape.

Semigroups containing proximal linear maps

Abstract: A linear automorphism of a finite dimensional real vector spaceV is calledproximal if it has a unique eigenvalue—counting multiplicities—of maximal modulus. Goldsheid and Margulis have shown that if a subgroupG of GL(V) contains a proximal element then so does every Zariski dense subsemigroupH ofG, providedV considered as aG-module is strongly irreducible. We here show thatH contains a finite subsetM such that for everyg∈GL(V) at least one of the elements γg, γ∈M, is proximal. We also give extensions and refinements of this result in the following directions: a quantitative version of proximality, reducible representations, several eigenvalues of maximal modulus.

Low-molecular-weight succinoglycan is predominantly produced by Rhizobium meliloti strains carrying a mutated ExoP protein characterized by a periplasmic N-terminal domain and a missing C-terminal domain

Abstract: Summary The membrane topology of the Rhizobium meliloti 2011 ExoP protein involved in polymerization and export of succinoglycan was analysed by translational fusions of lacZ and phoA reporter genes to the exoP gene. Based on this analysis, the ExoP protein could be divided into an N-terminal domain mainly located in the periplasmic space and a C-terminal domain located in the cytoplasm. Whereas the C-terminal domain of ExoP is characterized by a potential nucleotide-binding motif, the N-terminal ExoP domain contains the sequence motif‘PX2pX4SPKX11GXMXG1′, which is also present in proteins involved in the determination of O-antigen chain length. R. meliloti strains carrying mutated exoP* genes, exclusively encoding the N-terminal ExoP domain, produced a reduced amount of succinoglycan. This reduction could be suppressed by a mutation in the regulatory gene exoR. The ratio of low-molecular-weight to high-molecular-weight succinoglycan was significantly increased in the exoP* mutant strain. In the exoP*lexoR mutant strain only low-molecular-weight succinoglycan could be detected. Based on sequence homologies and similar hydropathic profiles, the N-terminal domain of ExoP was proposed to be a member of a protein family thought to be involved in polysaccharide chain-length determination.

Fertilization and early embryology: Recurrent failure in polar body formation and premature chromosome condensation in oocytes from a human patient: indicators of asynchrony in nuclear and cytoplasmic maturation

Abstract: All oocytes from a patient who had undergone four unsuccessful in-vitro fertilization attempts showed neither a polar body nor pronuclei when examined for fertilization. In 19 inseminated oocytes that were spread for karyotypic analysis, one haploid set of metaphase II chromosomes and a remarkable condensed structure were found. Hormonal and morphological criteria implied that the oocytes had been mature at the time of retrieval. Since non-inseminated oocytes contained only one set of metaphase II chromosomes, the condensed structure appeared to represent the sperm chromatin in the state of premature chromosome condensation due to a block in oocyte maturation. Since the first and second polar body, as well as their chromatin, were undetectable in all the patient's oocytes, a rapid maturation to metaphase II before retrieval and prolonged arrest in this state before fertilization, accompanied by degeneration of the first polar body, appear to be responsible for the condition. In accordance with this notion, degenerate spindles (typical of post-ovulatory aged oocytes) and separating chromosomes (probably representing presegregating chromatids) were observed by antitubulin immunofluorescence.

Globalization and Local Resistance: The Creation of Localities in Manila and Bangkok*

Abstract: Empfohlene Zitierung / Suggested Citation: Berner, E., & Korff, R. (1994). Globalization and local resistance: the creation of localities in Manila and Bangkok. (Working Paper / Universität Bielefeld, Fakultät für Soziologie, Forschungsschwerpunkt Entwicklungssoziologie, 205). Bielefeld: Universität Bielefeld, Fak. für Soziologie, Forschungsschwerpunkt Entwicklungssoziologie. https://nbnresolving.org/urn:nbn:de:0168-ssoar-423539

Extension of the Rhizobium meliloti succinoglycan biosynthesis gene cluster: Identification of the exsA gene encoding an ABC transporter protein, and the exsB gene which probably codes for a regulator of succinoglycan biosynthesis

Abstract: Two new genes, designated exsA and exsB, were identified adjacent to the 24 kb exo gene cluster of Rhizobium meliloti, which is involved in succinoglycan (EPS I) biosynthesis. The derived amino acid sequence of ExsA displayed significant homologies to ATP binding cassette (ABC) transporter proteins. R. meliloti strains mutated in exsA were characterized by a decreased ratio of HMW to LMW EPS I, indicating a function for ExsA in EPS I biosynthesis. The R. meliloti NdvA protein, which is involved in the transport of cyclic β-(1,2)-glucans, was identified as the closest homologue of ExsA. R. meliloti exsB mutants produced a three-fold increased amount of EPS I in comparison to the wild-type strain. In contrast, high copy number of exsB resulted in a decrease in the EPS I level to 20% of wild type, indicating that the exsB gene product can negatively influence EPS I biosynthesis. It was demonstrated that this influence is not due to transcriptional regulation of the exo genes by the exsB gene product. By plasmid integration it was shown that exsA and exsB represent monocistronic transcription units.

The superinfection exclusion gene (sieA) of bacteriophage P22: identification and overexpression of the gene and localization of the gene product.

Abstract: Previous work has shown that the sieA gene of Salmonella bacteriophage P22 is located between the genes mnt and 16. We cloned DNA fragments of the region into multicopy vectors and tested the transformants for mediating superinfection exclusion. Subcloning, phenotypical tests, and DNA sequencing resulted in the identification of the sieA gene. There are two possible initiation codons within one open reading frame of 492 or 480 bp. The deduced amino acid sequence leads to a hypothetical polypeptide with a calculated molecular mass of 18.8 or 18.3 kDa, respectively. According to three hydrophobic regions, all of which are long enough to span the membrane, the product of sieA should be a protein of the inner membrane of a P22-lysogenic cell of Salmonella typhimurium. The SieA protein was moderately overproduced from an expression vector in cultures of Escherichia coli and could be recovered from the membrane fraction.

Charmonium Composition and Nuclear Suppression

Abstract: We study charmonium production in hadron-nucleus collisions through the intermediate next-to-leading Fock space component $|(\bar{c}c)_8 g>$, formed by a colour octet $\bar{c}c$ pair and a gluon. We estimate the size of this state and show that its interaction with nucleons accounts for the observed charmonium suppression in nuclear interactions.

Local Instability of Orbits in Polygonal and Polyhedral Billiards

Abstract: We classify when local instability of orbits of closeby points can occur for billiards in two dimensional polygons, for billiards inside three dimensional polyhedra and for geodesic flows on surfaces of three dimensional polyhedra. We sharpen a theorem of Boldrighini, Keane and Marchetti. We show that polygonal and polyhedral billiards have zero topological entropy. We also prove that billiards in polygons are positive expansive when restricted to the set of non-periodic points. The methods used are elementary geometry and symbolic dynamics.