Corner transfer matrix renormalization group approach in the zoo of Archimedean lattices.

We develop a new methodology to contract tensor networks within the corner transfer matrix renormalization group approach for a wide range of two-dimensional lattice geometries. We discuss contraction algorithms on the example of triangular, kagome, honeycomb, square-octagon, star, ruby, square-hexagon-dodecahedron, and dice lattices. As benchmark tests, we apply the developed method to the classical Ising model on different lattices and observe a remarkable agreement of the results with the available from the literature. The approach also shows the necessary potential to be applied to various quantum lattice models in a combination with the wave-function variational optimization schemes.

[Monoclonal antibodies against protein Daxx and its localization in nuclear domains 10]. / Monoklonal'nye antitela k belku Daxx i ego lokalizatsiia v iadernykh domenakh 10.

Nuclear domains 10 (ND10) were first detected occasionally using antibodies to an antigen of unknown nature (Ascoli, Maul, 1991). Further on it was shown that ND10 were sites of locality of the number of proteins (PML, Sp 100, pRB) (Sterndorf et al., 1992; Kamitani et al., 1998), the majority of which are modified with ubiquitin-like small proteins-modifiers (SUMO) (Ishov, Maul, 1996). In addition, it was shown that ND10 were sites of primary localization, transcription and replication of some DNA-viruses (SV40, virus of simple herpes 1, adenovirus 5) (Ishov, Maul, 1996; Ishov et al., 1997). Except for SV40, these viruses produce proteins able to modify ND10, or leading to degradation of ND10-associated proteins (Maul et al., 1993; Maul, Everett, 1994). This degradation is accompanied with protein desumofication and, later, with hydrolysis on the ubiquitin-proteosomal way (Everett et al., 1998, 1999). Cell incubation with interferon leads to augmentation of the number and dimension of ND10 owing to increased expression of Sp100 and PML (Lavau et al., 1995; Grotzinger et al., 1996). In all, these data make it possible to put forward a hypothesis that ND10 may represent a peculiar cell storage ("dépôt") of proteins regulated according to the "accumulation-drop" principle (Ishov et al., 1997; Maul, 1998). However, this hypothesis requires further factual grounds.

PML is critical for ND10 formation and recruits the PML-interacting protein daxx to this nuclear structure when modified by SUMO-1.

Nuclear domain 10 (ND10), also referred to as nuclear bodies, are discrete interchromosomal accumulations of several proteins including promyelocytic leukemia protein (PML) and Sp100. In this study, we investigated the mechanism of ND10 assembly by identifying proteins that are essential for this process using cells lines that lack individual ND10-associated proteins. We identified the adapter protein Daxx and BML, the RecQ helicase missing in Bloom syndrome, as new ND10-associated proteins. PML, but not BLM or Sp100, was found to be responsible for the proper localization of all other ND10-associated proteins since they are dispersed in PML-/- cells. Introducing PML into this cell line by transient expression or fusion with PML-producing cells recruited ND10-associated proteins into de novo formed ND10 attesting to PMLs essential nature in ND10 formation. In the absence of PML, Daxx is highly enriched in condensed chromatin. Its recruitment to ND10 from condensed chromatin requires a small ubiquitin-related modifier (SUMO-1) modification of PML and reflects the interaction between the COOH-terminal domain of Daxx and PML. The segregation of Daxx from condensed chromatin in the absence of PML to ND10 by increased accumulation of SUMO-1-modified PML suggests the presence of a variable equilibrium between these two nuclear sites. Our findings identify the basic requirements for ND10 formation and suggest a dynamic mechanism for protein recruitment to these nuclear domains controlled by the SUMO-1 modification state of PML.