The 48 bp centromeric repeat is a functionally conserved motif in great apes and man showing protein-binding properties

The centromere-kinetochore complex is a chromosomal assembly site including repeat motifs and protein binding properties thus mediating chromosome motility and mitotic regulation. Next to the alpha-satellite DNA family as well as human satellite III DNA, contribution of other repetitive sequences has to be strongly considered in centromere function. Here, we report the identification of centromeric 48 bp motifs, isolated from chimpanzee and orang-utan using an orthologous human DNA probe. Applying Southern hybridization we show that these sequences are restricted to hominoid species. Diminishing hybrid formation in gibbons suggested that the 48 bp repeat originated approximately 25-20 million years ago. Consistently, both chimpanzee as well as human repeat probes failed to generate any hybridization signal with the monkey species Cercopithecus aethiops and Aotes trivirgatus. Sequence deviations from the consensus of human repeat monomers of 6% and 10.4% in chimpanzee and orang-utan, respectively, were found within a 16 bp region of the 48 bp repeat units. Gel mobility shift assays using chimpanzee repeat dimers as probes revealed peptide-binding properties with human and chimpanzee nuclear extracts. Species-specific DNA-protein complexes remained unaffected by competition studies and indicated the presence of at least one novel interacting protein consisting of two subunits with 90 and 95 kDa. Our data suggest that the 48 bp repeat, next to alpha-satellite DNA, provides essential sequence information for specific DNA-protein interaction and they imply phylogenetic conservation of these binding properties in primates. The complex is likely involved in the proper formation and/or function of mammalian centromeres.     

Frequency-locking phenomena of propagating wave fronts in reaction-diffusion systems

We observe N:(N-1)(N>/=2) frequency-locking phenomena of propagating wave fronts when increasing the light intensity in a spatially extended system. The experiments were carried out using the light-sensitive form of the Belousov-Zhabotinsky reaction with Ru(bpy)(2+)3 as a catalyst. By constructing a mapping function, the characteristic devil's staircase can be reproduced when plotting wave period versus light intensity, in agreement with the experimental data.     

Bridging fluorides and hard/soft mismatch in d6 and d8 complexes: the case of [Tl(mu-F)3Ru(PPh3)3

[RuCl2(PPh3)3] reacts with thallium(I) fluoride to give either [Tl(mu-F)3Ru(PPh3)3] (1) or [Tl(mu3-F)(mu2-Cl)2Ru2(mu2-Cl)(mu2-F)(PPh3)4] (2) depending on the excess of TlF used. Both 1 and 2 were fully characterized, including X-ray structure determinations. Complex 1 reacts with dihydrogen to form the known ruthenium hydride complex [Ru(H)2(H2)(PPh3)3] upon hydrogenolysis of the Ru-F bond. The reaction of 1 with activated alkyl bromides (R-Br) gives the corresponding alkyl fluorides and the trinuclear complex [Tl(mu3-F)(mu2-F)(mu2-X)Ru2(mu2-Br)(mu2-F)(PPh3)4] (X=Br, F) (3), whose structure closely resembles that of 2. However, 1 is not active as catalyst for the nucleophilic fluorination of R-Br in the presence of thallium fluoride. The effect of the bridging coordination mode of fluoride on the Ru-F bond is discussed in terms of the HSAB principle, which suggests a more general model for predicting the stability of d6 and d8 complexes containing hard ligands (such as fluoro, oxo, and amido).     

Symmetric identities on Bernoulli polynomials

In this paper, we obtain a generalization of an identity due to Carlitz on Bernoulli polynomials. Then we use this generalized formula to derive two symmetric identities which reduce to some known identities on Bernoulli polynomials and Bernoulli numbers, including the Miki identity.     

Glueing continuous functions constructively

The glueing of (sequentially, pointwise, or uniformly) continuous functions that coincide on the intersection of their closed domains is examined in the light of Bishop-style constructive analysis. This requires us to pay attention to the way that the two domains intersect.     

Optimization of the electrodeposition process of high-performance bismuth antimony telluride compounds for thermoelectric applications

High-quality films of bismuth antimony telluride were synthesized by electrodeposition from nitric acid electroplating baths. The influence of a surfactant, sodium ligninsulfonate, on the structure, morphology, stoichiometry, and homogeneity of the deposited films has been investigated. It was found that addition of this particular surfactant significantly improved the microstructural properties as well as homogeneity of the films with a significant improvement in the thermoelectric properties over those deposited in the absence of surfactant. A detailed microprobe analysis of the deposited films yielded a stoichiometric composition of Bi(0.35)Sb(1.33)Te(3) for the films electrodeposited in the absence of surfactant and a stoichiometry of Bi(0.32)Sb(1.33)Te(3) for films deposited in the presence of surfactant.     

Solving a bi-objective Transportation Location Routing Problem by metaheuristic algorithms

In this work we consider a Transportation Location Routing Problem (TLRP) that can be seen as an extension of the two stage Location Routing Problem, in which the first stage corresponds to a transportation problem with truck capacity. Two objectives are considered in this research, reduction of distribution cost and balance of workloads for drivers in the routing stage. Here, we present a mathematical formulation for the bi-objective TLRP and propose a new representation for the TLRP based on priorities. This representation lets us manage the problem easily and reduces the computational effort, plus, it is suitable to be used with both local search based and evolutionary approaches. In order to demonstrate its efficiency, it was implemented in two metaheuristic solution algorithms based on the Scatter Tabu Search Procedure for Non-Linear Multiobjective Optimization (SSPMO) and on the Non-dominated Sorting Genetic Algorithm II (NSGA-II) strategies. Computational experiments showed efficient results in solution quality and computing time.