Der Kirchenaustritt im staatlichen und kirchlichen Recht - recenzja

Recenzja: Der Kirchenaustritt im staatlichen und kirchlichen Recht, hg. E. Güthoff, S. Haering, H. Pree, Freiburg–Basel–Wien 2011, 179 s. [Quaestiones Disputatae, hg. P. Hünermann, Th. Söding, Bd. 243]

Molecular basis for SMC rod formation and its dissolution upon DNA binding.

SMC condensin complexes are central modulators of chromosome superstructure in all branches of life. Their SMC subunits form a long intramolecular coiled coil, which connects a constitutive "hinge" dimerization domain with an ATP-regulated "head" dimerization module. Here, we address the structural arrangement of the long coiled coils in SMC complexes. We unequivocally show that prokaryotic Smc-ScpAB, eukaryotic condensin, and possibly also cohesin form rod-like structures, with their coiled coils being closely juxtaposed and accurately anchored to the hinge. Upon ATP-induced binding of DNA to the hinge, however, Smc switches to a more open configuration. Our data suggest that a long-distance structural transition is transmitted from the Smc head domains to regulate Smc-ScpAB's association with DNA. These findings uncover a conserved architectural theme in SMC complexes, provide a mechanistic basis for Smc's dynamic engagement with chromosomes, and offer a molecular explanation for defects in Cornelia de Lange syndrome

Alternative Stacking Sequences in Hexagonal Boron Nitride

The relative orientation of successive sheets, i.e. the stacking sequence, in layered two-dimensional materials is central to the electronic, thermal, and mechanical properties of the material. Often different stacking sequences have comparable cohesive energy, leading to alternative stable crystal structures. Here we theoretically and experimentally explore different stacking sequences in the van der Waals bonded material hexagonal boron nitride (h-BN). We examine the total energy, electronic bandgap, and dielectric response tensor for five distinct high symmetry stacking sequences for both bulk and bilayer forms of h-BN. Two sequences, the generally assumed AA' sequence and the relatively unknown (for h-BN) AB (Bernal) sequence, are predicted to have comparably low energy. We present a scalable modified chemical vapor deposition method that produces large flakes of virtually pure AB stacked h-BN; this new material complements the generally available AA' stacked h-BN

Control of chromosome interactions by condensin complexes

Although condensin protein complexes have long been known for their central role during the formation of mitotic chromosomes, new evidence suggests they also act as global regulators of genome topology during all phases of the cell cycle. By controlling intra-chromosomal and inter-chromosomal DNA interactions, condensins function in various contexts of chromosome biology, from the regulation of transcription to the unpairing of homologous chromosomes. This review highlights recent advances in understanding how these global functions might be intimately linked to the molecular architecture of condensins and their extraordinary mode of binding to DNA

A Log-Quadratic Relation Between the Nuclear Black-Hole Masses and Velocity Dispersions of Galaxies

We demonstrate that a log-linear relation does not provide an adequate description of the correlation between the masses of Super-Massive Black-Holes (SMBH, M_bh) and the velocity dispersions of their host spheroid (sigma). An unknown relation between log(M_bh) and log(sigma) may be expanded to second order to obtain a log-quadratic relation of the form log(M_bh)=alpha+beta log(sigma/200) + beta_2[log(sigma/200)]^2. We perform a Bayesian analysis using the Nuker sample, and solve for beta, beta_2 and alpha, in addition to the intrinsic scatter (delta). We find unbiased parameter estimates of beta=4.2+/-0.37, beta_2=1.6+/-1.3 and delta=0.275+/-0.05. At the 80% level the M_bh-sigma relation does not follow a uniform power-law. Indeed, over the velocity range 70km/s<sigma<380km/s the logarithmic slope of the best fit relation varies between 2.7 and 5.1, which should be compared with a power-law estimate of 4.02+/-0.33. Assuming no systematic offset, single epoch virial SMBH masses estimated for AGN follow the same log-quadratic M_bh-sigma relation as the Nuker sample, but extend it downward in mass by an order of magnitude. The log-quadratic term in the M_bh-sigma relation has a significant effect on estimates of the local SMBH mass function at M_bh>10^9 solar masses, leading to densities of SMBHs with M_bh>10^10 solar masses that are several orders of magnitude larger than inferred from a log-linear relation. We also estimate unbiased parameters for the SMBH-bulge mass relation. With a parameterisation log(M_bh)=alpha_b + beta_b log(M_b/10^{11}) + beta_2b[log(M_b/10^{11})]^2, we find beta_b=1.15+/-0.18 and beta_2b=0.12+/-0.14. We determined an intrinsic scatter delta_b=0.41+/-0.07 which is ~50% larger than the scatter in the M_bh-sigma relation.Comment: 21 pages, 14 figures. Replaced to correct errors in published versio

Cohesin causes replicative DNA damage by trapping DNA topological stress

DNA topological stress inhibits DNA replication fork (RF) progression and contributes to DNA replication stress. In Saccharomyces cerevisiae, we demonstrate that centromeric DNA and the rDNA array are especially vulnerable to DNA topological stress during replication. The activity of the SMC complexes cohesin and condensin are linked to both the generation and repair of DNA topological-stress-linked damage in these regions. At cohesin-enriched centromeres, cohesin activity causes the accumulation of DNA damage, RF rotation, and pre-catenation, confirming that cohesin-dependent DNA topological stress impacts on normal replication progression. In contrast, at the rDNA, cohesin and condensin activity inhibit the repair of damage caused by DNA topological stress. We propose that, as well as generally acting to ensure faithful genetic inheritance, SMCs can disrupt genome stability by trapping DNA topological stress

Cloning, expression, crystallization and preliminary X-ray crystallographic analysis of a human condensin SMC2 hinge domain with short coiled coils

Kawahara, K., Nakamura, S., Katsu, Y., Motooka, D., Hosokawa, Y., Kojima, Y., Matsukawa, K., Takinowaki, H., Uchiyama, S., Kobayashi, Y., Fukui, K. & Ohkubo, T. (2010). Acta Cryst. F66, 1067-1070

The parsec scale region of Active Galactic Nuclei in the IR

First results from the AGN-Heidelberg program aimed at spatially resolving the central pc region of the closest Active Galactic Nuclei are presented. The core region of prototype active nuclei are clearly unveiled at IR waves and at distances from the nucleus - few pc- where circumnuclear starforming regions appear not to be present. Within that perspective, classical active nuclei as Circinus and NGC 1097, reveal with unprecedented detail clear channels of material being driven to the core whereas others as Centaurus A and NGC 1566, show a "clean" core environment. At the very center, a central compact region of about 2 pc scale is resolved in Circinus but not in the other cases challenging thus the universal presence of the putative obscuring torus.Comment: 4 pages, 6 color figures, To appear in the Proceedings of the IAU Symp. 222: "The Interplay among Black Holes, Stars and ISM in Galactic Nuclei" held in Gramado, Brazil, March 200