Mitsubishi Group (Japan)

Bacillus subtilis is the best-characterized member of the Gram-positive bacteria. Its genome of 4,214,810 base pairs comprises 4,100 protein-coding genes. Of these protein-coding genes, 53% are represented once, while a quarter of the genome corresponds to several gene families that have been greatly expanded by gene duplication, the largest family containing 77 putative ATP-binding transport proteins. In addition, a large proportion of the genetic capacity is devoted to the utilization of a variety of carbon sources, including many plant-derived molecules. The identification of five signal peptidase genes, as well as several genes for components of the secretion apparatus, is important given the capacity of Bacillus strains to secrete large amounts of industrially important enzymes. Many of the genes are involved in the synthesis of secondary metabolites, including antibiotics, that are more typically associated with Streptomyces species. The genome contains at least ten prophages or remnants of prophages, indicating that bacteriophage infection has played an important evolutionary role in horizontal gene transfer, in particular in the propagation of bacterial pathogenesis.

We present a methodology for analyzing polyphonic musical passages comprised of notes that exhibit a harmonically fixed spectral profile (such as piano notes). Taking advantage of this unique note structure, we can model the audio content of the musical passage by a linear basis transform and use non-negative matrix decomposition methods to estimate the spectral profile and the temporal information of every note. This approach results in a very simple and compact system that is not knowledge-based, but rather learns notes by observation.

Silver nanoparticles were produced by laser ablation of a metal silver plate in an aqueous solution of sodium dodecyl sulfate, C12H25OSO3Na. The absorption spectrum of the silver nanoparticles is found to be essentially the same as that of silver nanoparticles chemically prepared in a solution. The size distribution of the nanoparticles measured by an electron microscope shifts to a smaller size with increase in the concentration of sodium dodecyl sulfate and with a decrease in the irradiation laser power. These findings are explained by a scheme that the nanoparticles are formed via rapid formation of an embryonic silver particle and a consecutive slow particle growth in competition with termination of the growth due to SDS coating on the particle.

The technology of intelligent agents and multi-agent systems is expected to alter radically the way in which complex, distributed, open systems are conceptualised and implemented. The paper considers the problem of building a multi-agent system as a software engineering enterprise. Three issues are focused on: how agents might be specified; how these specifications might be refined or otherwise transformed into efficient implementations; and how implemented agents and multi-agent systems might subsequently be verified, to show that they are correct with respect to their specifications. These issues are discussed with reference to a number of case studies. The paper concludes by setting out some issues and open problems for future research.

The mushroom body (MB) is an important centre for higher order sensory integration and learning in insects. To analyse the development and organisation of the MB neuropile in Drosophila, we performed cell lineage analysis in the adult brain with a new technique that combines the Flippase (flp)/FRT system and the GAL4/UAS system. We showed that the four mushroom body neuroblasts (MBNbs) give birth exclusively to the neurones and glial cells of the MB, and that each of the four MBNb clones contributes to the entire MB structure. The expression patterns of 19 GAL4 enhancer-trap strains that mark various subsets of MB cells revealed overlapping cell types in all four of the MBNb lineages. Partial ablation of MBNbs using hydroxyurea showed that each of the four neuroblasts autonomously generates the entire repertoire of the known MB substructures.

Knock-in embryonic stem (ES) cells, in which GFP or lacZ was expressed from the endogenous mouse vasa homolog (Mvh), which is specifically expressed in differentiating germ cells, were used to visualize germ cell production during in vitro differentiation. The appearance of MVH-positive germ cells depended on embryoid body formation and was greatly enhanced by the inductive effects of bone morphogenic protein 4-producing cells. The ES-derived MVH-positive cells could participate in spermatogenesis when transplanted into reconstituted testicular tubules, demonstrating that ES cells can produce functional germ cells in vitro. In vitro germ cell differentiation provides a paradigm for studying the molecular basis of germ line establishment, as well as for developing new approaches to reproductive engineering.

The expression of the genes for the major outer membrane proteins OmpF and OmpC are osmoregulated. The ompC locus was found to be transcribed bidirectionally under conditions of high osmolarity and a 174-base transcript encoded upstream of ompC was found to inhibit the OmpF production and to substantially reduce the amount of the ompF mRNA. This RNA [mRNA-interfering complementary RNA (micRNA)] has a long sequence that is complementary to the 5' end region of the ompF mRNA. We propose that the micRNA inhibits the translation of the ompF mRNA by hybridizing with it. This RNA interaction may cause premature termination of the transcription of the ompF gene or destabilization of the ompF mRNA or both.

Throughout this article, we concentrate on the transcoding of block-based video coding schemes that use hybrid discrete cosine transform (DCT) and motion compensation (MC). In such schemes, the frames of the video sequence are divided into macroblocks (MBs), where each MB typically consists of a luminance block (e.g., of size 16 × 16, or alternatively, four 8 × 8 blocks) along with corresponding chrominance blocks (e.g., 8 × 8 Cb and 8 × 8 Cr). This article emphasizes the processing that is done on the luminance components of the video. In general, the chrominance components can be handled similarly and will not be discussed in this article. We first provide an overview of the techniques used for bit-rate reduction and the corresponding architectures that have been proposed. Then, we describe the advances regarding spatial and temporal resolution reduction techniques and architectures. Additionally, an overview of error resilient transcoding is also provided, as well as a discussion of scalable coding techniques and how they relate to video transcoding. Finally, the article ends with concluding remarks, including pointers to other works on video transcoding that have not been covered in this article, as well as some future directions.

The compressive sensing (CS) framework aims to ease the burden on analog-to-digital converters (ADCs) by reducing the sampling rate required to acquire and stably recover sparse signals. Practical ADCs not only sample but also quantize each measurement to a finite number of bits; moreover, there is an inverse relationship between the achievable sampling rate and the bit depth. In this paper, we investigate an alternative CS approach that shifts the emphasis from the sampling rate to the number of bits per measurement. In particular, we explore the extreme case of 1-bit CS measurements, which capture just their sign. Our results come in two flavors. First, we consider ideal reconstruction from noiseless 1-bit measurements and provide a lower bound on the best achievable reconstruction error. We also demonstrate that i.i.d. random Gaussian matrices provide measurement mappings that, with overwhelming probability, achieve nearly optimal error decay. Next, we consider reconstruction robustness to measurement errors and noise and introduce the binary <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\epsilon $</tex></formula> -stable embedding property, which characterizes the robustness of the measurement process to sign changes. We show that the same class of matrices that provide almost optimal noiseless performance also enable such a robust mapping. On the practical side, we introduce the binary iterative hard thresholding algorithm for signal reconstruction from 1-bit measurements that offers state-of-the-art performance.

The recently introduced theory of compressive sensing enables the recovery of sparse or compressible signals from a small set of nonadaptive, linear measurements. If properly chosen, the number of measurements can be much smaller than the number of Nyquist-rate samples. Interestingly, it has been shown that random projections are a near-optimal measurement scheme. This has inspired the design of hardware systems that directly implement random measurement protocols. However, despite the intense focus of the community on signal recovery, many (if not most) signal processing problems do not require full signal recovery. In this paper, we take some first steps in the direction of solving inference problems-such as detection, classification, or estimation-and filtering problems using only compressive measurements and without ever reconstructing the signals involved. We provide theoretical bounds along with experimental results.

Gold nanoparticles were produced by laser ablation of a gold metal plate in an aqueous solution of sodium dodecyl sulfate. The absorption spectrum of the gold nanoparticles was essentially same as that of gold nanoparticles chemically prepared in a solution. The size distribution of the nanoparticles thus produced was measured by an electron microscope and was found to shift to a smaller size with an increase in surfactant concentration. This behavior is explained in terms of the dynamic formation model. Dependence of the nanoparticle abundance on surfactant concentration in the solution shows that stable gold nanoparticles tend to be formed as the surfactant concentration exceeds 10-5 M. The gold nanoparticles having diameters larger than 5 nm were pulverized into those having diameters of 1−5 nm by a 532-nm laser.

Restricted expression of a mouse Vasa homolog gene (Mvh) expression is first detected in primordial germ cells (PGCs) after colonization of the genital ridges. Subsequently, Mvh is maintained until postmeiotic germ cells are formed. Here, we demonstrate that male mice homozygous for a targeted mutation of Mvh exhibit a reproductive deficiency. Male homozygotes produce no sperm in the testes, where premeiotic germ cells cease differentiation by the zygotene stage and undergo apoptotic death. In addition, the proliferation of PGCs that colonize homozygous male gonads is significantly hampered, and OCT-3/4 expression appears to be reduced. These results indicate that the loss of Mvh function causes a deficiency in the proliferation and differentiation of mouse male germ cells.

Nonlinear support vector machines (SVMs) are investigated for appearance-based gender classification with low-resolution "thumbnail" faces processed from 1,755 images from the FERET (FacE REcognition Technology) face database. The performance of SVMs (3.4% error) is shown to be superior to traditional pattern classifiers (linear, quadratic, Fisher linear discriminant, nearest-neighbor) as well as more modern techniques, such as radial basis function (RBF) classifiers and large ensemble-RBF networks. Furthermore, the difference in classification performance with low-resolution "thumbnails" (21/spl times/12 pixels) and the corresponding higher-resolution images (84/spl times/48 pixels) was found to be only 1%, thus demonstrating robustness and stability with respect to scale and the degree of facial detail.

The biochemistry of amyloid proteins has been a fascinating and important area of research because of its contribution to our understanding of protein folding dynamics and assembly and of the pathogenetic mechanisms of human disease. One such disease is AD, 2The abbreviations used are: AD, Alzheimer disease; Aβ, amyloid β-protein; Met35(O), Met35 sulfoxide; AFM, atomic force microscopy; CAA, cerebral amyloid angiopathy; ADDLs, Aβ-derived diffusible ligands.2The abbreviations used are: AD, Alzheimer disease; Aβ, amyloid β-protein; Met35(O), Met35 sulfoxide; AFM, atomic force microscopy; CAA, cerebral amyloid angiopathy; ADDLs, Aβ-derived diffusible ligands. the most common neurodegenerative disorder of aging. In AD, Aβ (Fig. 1A), which is expressed normally and ubiquitously throughout life as a 40–42-residue peptide, forms fibrils that deposit in the brain as "amyloid plaques." This pathologic deposition process led researchers to investigate fibril formation as a target for therapeutic intervention. In doing so, an increasing number of fibril precursors and nonfibrillar Aβ assemblies have been identified, the majority of which are neurotoxic. These findings have altered prevailing fibril-centered views of the pathobiology of amyloid diseases (1Kirkitadze M.D. Bitan G. Teplow D.B. J. Neurosci. Res. 2002; 69: 567-577Crossref PubMed Scopus (503) Google Scholar) and intensified efforts to understand the early folding and assembly dynamics of Aβ. In the discussion that follows, we seek to introduce the reader to the complex world of Aβ assembly and biological activity, a goal we hope will provide a conceptual framework upon which further knowledge or experimentation may be built.Aβ Fibril StructureThe determination of the structure of fibrils has been an unusually difficult problem because Aβ belongs to a class of proteins that are "natively unfolded" (2Nelson R. Eisenberg D. Curr. Opin. Struct. Biol. 2006; 16: 260-265Crossref PubMed Scopus (322) Google Scholar) and preferentially form amyloid fibrils rather than protein crystals. This has precluded x-ray diffraction studies of full-length Aβ and made solution NMR studies problematic (3Teplow D.B. Methods Enzymol. 2006; 413: 20-33Crossref PubMed Scopus (169) Google Scholar). Nevertheless, site-directed spin labeling and solid-state NMR studies have been informative. The former studies have revealed that Aβ fibrils comprise β-strands organized in a parallel, in-register fashion. The latter studies showed that in Aβ40 fibrils, residues 12–24 and 30–40 form parallel β-sheets and that these two β-strand segments are connected by a turn involving residues 25–29 (4Tycko R. Methods Enzymol. 2006; 413: 103-122Crossref PubMed Scopus (47) Google Scholar). Hydrogen/deuterium exchange coupled with solution-state NMR revealed a similar, but distinct, segmental arrangement of β-strands within Aβ42 fibrils. Here, residues 18–26 and 31–42 form the β-strands. In both models, salt bridges between Asp23 and Lys28 stabilize the turn region connecting the two β-strands (2Nelson R. Eisenberg D. Curr. Opin. Struct. Biol. 2006; 16: 260-265Crossref PubMed Scopus (322) Google Scholar, 5Finder V.H. Glockshuber R. Neurodegener. Dis. 2007; 4: 13-27Crossref PubMed Scopus (253) Google Scholar). Similar findings have been obtained using other methods (5Finder V.H. Glockshuber R. Neurodegener. Dis. 2007; 4: 13-27Crossref PubMed Scopus (253) Google Scholar, 6Fändrich M. CMLS Cell. Mol. Life Sci. 2007; 64: 2066-2078Crossref PubMed Scopus (198) Google Scholar).Differences among the studies likely result from the examination of different peptides (Aβ40 versus Aβ42), the absence or presence of Met35(O), or the conditions under which fibrils were formed. All these factors have been shown to affect significantly peptide assembly and biological activity (6Fändrich M. CMLS Cell. Mol. Life Sci. 2007; 64: 2066-2078Crossref PubMed Scopus (198) Google Scholar, 7Kodali R. Wetzel R. Curr. Opin. Struct. Biol. 2007; 17: 48-57Crossref PubMed Scopus (319) Google Scholar). Although no crystal structures have been determined with full-length Aβ, exciting work has been done on microcrystals formed by C-terminal peptides. These microcrystals yield diffraction patterns consistent with an in-register cross-β-organization of two interdigitated β-sheets. This "steric zipper" structure has been found in at least 13 other amyloid protein microcrystals (8Sawaya M.R. Sambashivan S. Nelson R. Ivanova M.I. Sievers S.A. Apostol M.I. Thompson M.J. Balbirnie M. Wiltzius J.J.W. McFarlane H.T. Madsen A. Riekel C. Eisenberg D. Nature. 2007; 447: 453-457Crossref PubMed Scopus (1783) Google Scholar). Whether steric zippers exists in Aβ fibrils is unclear.Pathways of Peptide AssemblyHow do monomers form fibrils? This question is fundamental to understanding fibrillogenesis and for identifying assembly steps that could be therapeutic targets. Influential early investigations promulgated the idea that Aβ assembly was a specific example of the general class of nucleation-dependent polymerization reactions (Fig. 1B). These reactions comprise a slow nucleation step, producing a "lag phase" during assembly monitoring, followed by a rapid fibril elongation step. Operating within this paradigm, nucleation (kn) and elongation (ke) rate constants for Aβ fibril formation were determined (9Teplow D.B. Amyloid. 1998; 5: 121-142Crossref PubMed Scopus (287) Google Scholar). However, continuing elucidation of this ostensibly classical polymerization process revealed unexpected complexity in the numbers and types ("on-pathway" or "off-pathway" for fibril formation) of assembly paths and the structures resulting therefrom (Fig. 1C and supplemental Table S1).Protofibrils, Paranuclei, and Monomer FoldsFig. 1C illustrates one pathway of fibril assembly. The penultimate fibril intermediate, the protofibril, was first identified more than a decade ago (10Caughey B. Lansbury P.T. Annu. Rev. Neurosci. 2003; 26: 267-298Crossref PubMed Scopus (1433) Google Scholar). Protofibrils were described as beaded chains, each bead of which was ∼5 nm in diameter. The length of these structures generally was <150 nm. Kinetics and solution-phase AFM experiments showed that protofibrils matured into fibrils (10Caughey B. Lansbury P.T. Annu. Rev. Neurosci. 2003; 26: 267-298Crossref PubMed Scopus (1433) Google Scholar). To understand how protofibrils formed, methods were developed to determine quantitatively the oligomer size distribution in nascent Aβ preparations (11Bitan G. Teplow D.B. Acc. Chem. Res. 2004; 37: 357-364Crossref PubMed Scopus (174) Google Scholar). In Aβ42 assembly, these experiments suggested that a pentamer or hexamer, the "paranucleus," was the basic unit of the protofibril and that the beaded chains comprising protofibrils formed by the self-association of paranuclei.To understand the oligomerization process in atomic detail, computer simulations have been done (12Urbanc B. Cruz L. Yun S. Buldyrev S.V. Bitan G. Teplow D.B. Stanley H.E. Proc. Natl. Acad. Sci. U. S. A. 2004; 101: 17345-17350Crossref PubMed Scopus (295) Google Scholar). These studies yielded oligomer frequency distributions similar to those determined experimentally, but in addition provided high resolution conformational information. Aβ40 oligomers were more compact than Aβ42 oligomers due to increased conformational freedom of the Aβ42 N termini. This suggested that intermolecular interactions among Aβ42 N termini might facilitate the C-terminal interactions obligatory for fibril formation. The work also revealed the formation of a turn in Aβ42 at Gly37-Gly38 that was not observed in Aβ40 and that thus could be critical in paranucleus formation.The importance of the C terminus of Aβ in controlling Aβ assembly has also been revealed in experiments involving amino acid substitutions (11Bitan G. Teplow D.B. Acc. Chem. Res. 2004; 37: 357-364Crossref PubMed Scopus (174) Google Scholar). Systematic alterations in residue 41 side chain hydrophobicity showed that Gly or Ala largely eliminated paranucleus formation, whereas amino acids with hydropathic characteristics similar to Ile had no effect. Elimination of the Ala42 side chain blocked paranucleus self-association, whereas insertion of larger apolar side chains facilitated the process. Similar studies examined Met35 polarity, an important question with respect to redox chemistry in AD (5Finder V.H. Glockshuber R. Neurodegener. Dis. 2007; 4: 13-27Crossref PubMed Scopus (253) Google Scholar, 11Bitan G. Teplow D.B. Acc. Chem. Res. 2004; 37: 357-364Crossref PubMed Scopus (174) Google Scholar). In these experiments, oxidation of Met35 to Met35(O) or Met35 sulfone had no effect on Aβ40 oligomerization, whereas Aβ42 paranucleus formation was abolished. Interestingly, the modified Aβ42 peptides oligomerized identically to Aβ40.The relative importance of the C terminus in controlling Aβ assembly was also apparent in studies of Aβ40 and Aβ42 peptides containing substitutions linked to familial forms of AD or CAA. These substitutions (Glu22 → Gln, Glu22 → Gly, Glu22 → Lys, and Asp23 → Asn) produced oligomers of higher order when substituted in Aβ40 but had little effect on Aβ42 oligomerization. Removal of N-terminal residues Asp1–Gly9 in Aβ42 had no effect on its oligomer size distribution, whereas truncation of either the N-terminal two or four residues of Aβ40 produced higher-order oligomers. This observation was consistent with the aforementioned simulation data that suggested that collapse of the N terminus of Aβ40 on the oligomer surface might shield underlying hydrophobic regions of the oligomers that otherwise might interact to form higher-order assemblies (12Urbanc B. Cruz L. Yun S. Buldyrev S.V. Bitan G. Teplow D.B. Stanley H.E. Proc. Natl. Acad. Sci. U. S. A. 2004; 101: 17345-17350Crossref PubMed Scopus (295) Google Scholar). In fact, this process was observed in studies of the folding and assembly of urea-denatured Aβ (13Chen Y.-R. Glabe C.G. J. Biol. Chem. 2006; 281: 24414-24422Abstract Full Text Full Text PDF PubMed Scopus (172) Google Scholar). Aβ40 formed an unstable but largely collapsed monomeric species, whereas Aβ42 existed in a trimeric or tetrameric state (13Chen Y.-R. Glabe C.G. J. Biol. Chem. 2006; 281: 24414-24422Abstract Full Text Full Text PDF PubMed Scopus (172) Google Scholar).The solvent inaccessibility of the Ala21–Ala30 region of Aβ likely results from the formation of a turn-like structure that nucleates monomer folding (14Teplow D.B. Lazo N.D. Bitan G. Bernstein S. Wyttenbach T. Bowers M.T. Baumketner A. Shea J.-E. Urbanc B. Cruz L. Borreguero J. Stanley H.E. Acc. Chem. Res. 2006; 39: 635-645Crossref PubMed Scopus (192) Google Scholar). This decapeptide region initially was identified due to its resistance to proteolysis, a resistance that remained in the isolated decapeptide itself and that allowed NMR and computational determinations of its structure and dynamics (14Teplow D.B. Lazo N.D. Bitan G. Bernstein S. Wyttenbach T. Bowers M.T. Baumketner A. Shea J.-E. Urbanc B. Cruz L. Borreguero J. Stanley H.E. Acc. Chem. Res. 2006; 39: 635-645Crossref PubMed Scopus (192) Google Scholar). Most recently, thermodynamics studies showed that the turn is destabilized by amino acid substitutions that cause AD and CAA (15Grant M.A. Lazo N.D. Lomakin A. Condron M.M. Arai H. Yamin G. Rigby A.C. Teplow D.B. Proc. Natl. Acad. Sci. U. S. A. 2007; 104: 16522-16527Crossref PubMed Scopus (103) Google Scholar). Destabilization correlates with accelerated Aβ oligomerization and higher-order assembly and thus provides a mechanistic explanation for these familial forms of AD and CAA.Other Assembly PathwaysThe idea that an Aβ hexamer building block exists is intriguing because at least four other structures, ADDLs, Aβ*56, "globulomers," and "Aβ oligomers," comprise multiples of this basic unit (Fig. 1C and supplemental Table S1). ADDLs are dodecamers produced in vitro from Aβ42 using special solvent conditions and appear in AFM studies as globular structures with heights of 5–6 nm (16Lambert M.P. Barlow A.K. Chromy B.A. Edwards C. Freed R. Liosatos M. Morgan T.E. Rozovsky I. Trommer B. Viola K.L. Wals P. Zhang C. Finch C.E. Krafft G.A. Klein W.L. Proc. Natl. Acad. Sci. U. S. A. 1998; 95: 6448-6453Crossref PubMed Scopus (3082) Google Scholar). Aβ*56 was identified in SDS extracts from brains of Tg2576 transgenic mice (17Lesné S. Koh M.T. Kotilinek L. Kayed R. Glabe C.G. Yang A. Gallagher M. Ashe K.H. Nature. 2006; 440: 352-357Crossref PubMed Scopus (2404) Google Scholar). The "56" refers to the molecular weight of the oligomer, which is consistent with that of a dodecamer. The morphology of Aβ*56 is a prolate ellipsoid. A third type of dodecamer is the globulomer (so-called because it is a globular oligomer), which is formed by Aβ42 in the presence of SDS (18Gellermann G.P. Byrnes H. Striebinger A. Ullrich K. Mueller R. Hillen H. Barghorn S. Neurobiol. Dis. 2008; 30: 212-220Crossref PubMed Scopus (98) Google Scholar). Protease digestion, antibody binding, and mass spectrometry studies of globulomers suggest a structural model in which the hydrophobic C terminus (residues 24–42) forms a stable core and the more hydrophilic N terminus is on the surface. Although globulomers have substantial β-sheet content, presumably at the C terminus, they do not form fibrils and thus may be considered an off-pathway assembly (18Gellermann G.P. Byrnes H. Striebinger A. Ullrich K. Mueller R. Hillen H. Barghorn S. Neurobiol. Dis. 2008; 30: 212-220Crossref PubMed Scopus (98) Google Scholar). A larger species, the Aβ oligomer, also has been produced in vitro (19Deshpande A. Mina E. Glabe C. Busciglio J. J. Neurosci. 2006; 26: 6011-6018Crossref PubMed Scopus (441) Google Scholar). Its molecular weight (∼90,000) suggests that its assembly order is ∼15–20, consistent with that of an octadecamer. In addition to assemblies with globular morphology, annular pore-like structures with diameters of 8–12 nm and pore sizes of 2–2.5 nm also have been described (10Caughey B. Lansbury P.T. Annu. Rev. Neurosci. 2003; 26: 267-298Crossref PubMed Scopus (1433) Google Scholar, 20Haass C. Selkoe D.J. Nat. Rev. Mol. Cell Biol. 2007; 8: 101-112Crossref PubMed Scopus (3811) Google Scholar).The largest globular assemblies are amylospheroids and β-amyloid balls. Amylospheroids are off-pathway spheroidal structures with diameters of 10–15 nm that are formed by Aβ40 or Aβ42 (21Hoshi M. Sato M. Matsumoto S. Noguchi A. Yasutake K. Yoshida N. Sato K. Proc. Natl. Acad. Sci. U. S. A. 2003; 100: 6370-6375Crossref PubMed Scopus (436) Google Scholar). β-Amyloid balls are very large (20–200 μm) spheroidal structures formed only by Aβ40 at high concentration (300–600 μm) (22Westlind-Danielsson A. Arnerup G. Biochemistry. 2001; 40: 14736-14743Crossref PubMed Scopus (57) Google Scholar). Although such concentrations are non-physiological with respect to the average concentration of soluble Aβ in vivo, β-amyloid balls may be an interesting model of amyloid plaques or of the inclusion bodies formed in Parkinson and Huntington diseases and in the transmissible spongiform encephalopathies.Assembly Complexity and ProvenanceThe complexity of Aβ assembly complicates the determination of precursor-product relationships. For example, are the different dodecameric assemblies discussed above really different, or are they all the same entity described in different ways by different investigators? Do the different larger spheroidal assemblies form from the same hexamer building blocks that produce dodecamers and thus belong on the same pathway? We do not know, but the answers to these questions are important because they have implications for the development of therapeutic agents targeting critical steps in the assembly pathways. For example, recent work has shown that compounds exist that can efficiently inhibit fibril formation or oligomerization, but not both (23Necula M. Kayed R. Milton S. Glabe C.G. J. Biol. Chem. 2007; 282: 10311-10324Abstract Full Text Full Text PDF PubMed Scopus (595) Google Scholar). The distinction is critical if one assembly is benign and the other toxic.Aβ Assembly and DiseaseThus far, we have discussed basic aspects of the physical biochemistry of Aβ assembly. However, the most fundamental biological question is, "what is the relationship between Aβ assemblies and AD?" Strong linkage exists between amyloid formation per se and disease (for a comprehensive review, see Ref. 24Sipe J.C. Amyloid Proteins: The Beta Sheet Conformation and Disease. Wiley-VCH, Weinheim, Germany2005Crossref Scopus (22) Google Scholar), and this linkage formed, in part, the foundation for the "amyloid cascade hypothesis," which posited that amyloid fibril formation was the key pathogenetic process in AD (25Hardy J. Ann. Med. 1996; 28: 255-258Crossref PubMed Scopus (60) Google Scholar). As discussed above, elucidation of the mechanisms of fibril formation unexpectedly revealed a broad range of fibrillar and nonfibrillar structures (supplemental Table S1). Aβ oligomers appear to be particularly important because they are potent neurotoxins and are isolable from AD patients, and their concentrations correlate positively with neuropathology in vivo. These facts have produced a fundamental paradigm shift resulting in a revised amyloid cascade hypothesis (1Kirkitadze M.D. Bitan G. Teplow D.B. J. Neurosci. Res. 2002; 69: 567-577Crossref PubMed Scopus (503) Google Scholar, 20Haass C. Selkoe D.J. Nat. Rev. Mol. Cell Biol. 2007; 8: 101-112Crossref PubMed Scopus (3811) Google Scholar, 26Hardy J. Selkoe D.J. Science. 2002; 297: 353-356Crossref PubMed Scopus (10796) Google Scholar), one that posits the primacy of oligomeric forms of Aβ in AD causation.A substantial experimental corpus exists demonstrating that "Aβ" is neurotoxic (27Yankner B.A. Lu T. J. Biol. Chem. 2009; 284: 4755-4759Abstract Full Text Full Text PDF PubMed Scopus (166) Google Scholar). However, it was not until approximately a decade ago, with the discovery and characterization of protofibrils and ADDLs, that a more structurally precise definition of Aβ could be made, one that in turn enabled more precise structure-neurotoxicity correlations to be established (16Lambert M.P. Barlow A.K. Chromy B.A. Edwards C. Freed R. Liosatos M. Morgan T.E. Rozovsky I. Trommer B. Viola K.L. Wals P. Zhang C. Finch C.E. Krafft G.A. Klein W.L. Proc. Natl. Acad. Sci. U. S. A. 1998; 95: 6448-6453Crossref PubMed Scopus (3082) Google Scholar, 28Walsh D.M. Hartley D.M. Kusumoto Y. Fezoui Y. Condron M.M. Lomakin A. Benedek G.B. Selkoe D.J. Teplow D.B. J. Biol. Chem. 1999; 274: 25945-25952Abstract Full Text Full Text PDF PubMed Scopus (979) Google Scholar). Each new assembly subsequently discovered also was toxic. An important goal of current research is to better define the mechanisms of this toxicity, a variety of which we now discuss.Membrane EffectsAβ is an amphipathic peptide (Fig. 1A). The side chains of 16 of the first 28 residues are polar; 12 are charged at neutral pH. The remaining 12 (Aβ40) or 14 (Aβ42) side chains are apolar. Structures such as these can form micelles (29Lomakin A. Chung D.S. Benedek G.B. Kirschner D.A. Teplow D.B. Proc. Natl. Acad. Sci. U. S. A. 1996; 93: 1125-1129Crossref PubMed Scopus (730) Google Scholar) or interact with membranes directly. Recent work has shown that Aβ40 inserts into membranes of hippocampal neurons from AD brains (30Verdier Y. Zarndi M. Penke B. J. Pept. Sci. 2004; 10: 229-248Crossref PubMed Scopus (236) Google Scholar). Membrane insertion can perturb plasma membrane structure and function. For example, conformational analysis of the C-terminal domain of Aβ (residues 29–40/2) has shown it to have properties similar to those of fusion peptides of viral proteins. Insertion of these fragments in a tilted manner in the membrane is thought to disrupt the parallel symmetry of the fatty acyl chains, altering the curvature of the membrane surface and destabilizing the membrane. Consistent with this prediction, Aβ(22–42) induces membrane fusion and permeabilizes lipid vesicles that mimic neuronal membranes (31Arispe N. Diaz J.C. Simakova O. 2007; PubMed Scopus Google oligomers have also been shown to the of lipid and membranes by the by increasing the membrane structural or the membrane the Y. Kayed R. A. Glabe C. J. 2006; PubMed Scopus Google Scholar). These may be to of membrane and which in turn may to and (30Verdier Y. Zarndi M. Penke B. J. Pept. Sci. 2004; 10: 229-248Crossref PubMed Scopus (236) Google Scholar, Y. R. S. G. M. T. J. Biol. Chem. 2004; Full Text Full Text PDF PubMed Scopus Google membrane may also Aβ40 oligomers form in neuronal plasma membranes and (30Verdier Y. Zarndi M. Penke B. J. Pept. Sci. 2004; 10: 229-248Crossref PubMed Scopus (236) Google Scholar, M. N. Y. E. J. Full Text PDF PubMed Scopus Google Scholar). These may comprise four to each of which is an Aβ oligomer of order four to and thus the comprise a of Aβ The are that formation is a process (31Arispe N. Diaz J.C. Simakova O. 2007; PubMed Scopus Google Scholar). For example, (31Arispe N. Diaz J.C. Simakova O. 2007; PubMed Scopus Google Scholar) have shown that Aβ40 activity in lipid results in to higher AFM of have revealed structures with pore-like of and diameter. However, pore formation a that Aβ with the surface of lipid the membrane and may produce the of AFM experiments have revealed that Aβ nm in size form the of a result that could be as pore formation L. C. M. A. J. U. J. Mol. Biol. 2004; PubMed Scopus Google Scholar). Consistent with this are recent results that oligomers membrane Y. Kayed R. A. Glabe C. J. 2006; PubMed Scopus Google that two general of may structural interactions of the type discussed and specific These latter interactions may fibrillar and oligomeric forms of Aβ that either as or membrane Aβ have been identified (30Verdier Y. Zarndi M. Penke B. J. Pept. Sci. 2004; 10: 229-248Crossref PubMed Scopus (236) Google Scholar), but the important question that is these interactions are or and exists that are in the of However, this is a that We a number of mechanistic vitro results that concentrations of and can Aβ and Aβ S. S. Chem. 2007; Scopus Google Scholar, Neurosci. 2003; 26: Full Text Full Text PDF PubMed Scopus Google Scholar). Aβ has a and for and M. N. Y. E. J. Full Text PDF PubMed Scopus Google Scholar). NMR and have suggested that the residues in Aβ, and This complex has been to chemistry which and is also thought to in this In addition to its in it has been suggested that of C. R. D. Cell. Full Text PDF PubMed Scopus Google A for redox chemistry is Met35 D.A. Curr. Med. Chem. 2003; 10: PubMed Scopus Google Scholar). The of by Aβ of or a that may the oxidation of Met35 to its or produced in this may with molecular and biological agents or to yield and the J. J. Cell Biol. 2008; 40: PubMed Scopus Google Scholar). The thus produced can further Met35 to its form and also with in a to produce Interestingly, the Met35(O) and Met35 sulfone forms of Aβ do not as the peptide (11Bitan G. Teplow D.B. Acc. Chem. Res. 2004; 37: 357-364Crossref PubMed Scopus (174) Google Scholar, L. I. J. Biol. Chem. 2002; Full Text Full Text PDF PubMed Scopus Google Scholar). L. I. J. Biol. Chem. 2002; Full Text Full Text PDF PubMed Scopus Google Scholar) have that oxidation of Met35 to Met35(O) significantly the rate of amyloid formation and fibril Bitan and Teplow (11Bitan G. Teplow D.B. Acc. Chem. Res. 2004; 37: 357-364Crossref PubMed Scopus (174) Google Scholar) similar findings and found that Met35(O) Aβ42 not form but rather to These in vitro are consistent with the that exists between and Aβ deposition in AD (11Bitan G. Teplow D.B. Acc. Chem. Res. 2004; 37: 357-364Crossref PubMed Scopus (174) Google Scholar, D.A. Curr. Med. Chem. 2003; 10: PubMed Scopus Google K. K. H. H. M. T. T. J. Chem. PubMed Scopus Google Scholar) have that is also in redox suggested that produced by to produce the which the of Met35 and an A turn at the C-terminal to the it and a hydrophobic peptide oligomerization, fibril formation, and has been linked to the process K. Res. 2007; 10: PubMed Scopus Google Scholar), a process that is the largest for of by Aβ assemblies may the linkage of both and Aβ to suggests that in The of full-length Aβ or forms with potent of chain and in the of acid to of pore increased and membrane and K. Res. 2007; 10: PubMed Scopus Google Scholar, C. G. D. D.A. 2007; PubMed Scopus Google Scholar). of Aβ with a or with protein also this type of J. Dis. 2007; PubMed Scopus (98) Google common pathway of neuronal is This pathway is particularly likely to

Mushroom bodies are prominent neuropils found in annelids and in all arthropod groups except crustaceans. First explicitly identified in 1850, the mushroom bodies differ in size and complexity between taxa, as well as between different castes of a single species of social insect. These differences led some early biologists to suggest that the mushroom bodies endow an arthropod with intelligence or the ability to execute voluntary actions, as opposed to innate behaviors. Recent physiological studies and mutant analyses have led to divergent interpretations. One interpretation is that the mushroom bodies conditionally relay to higher protocerebral centers information about sensory stimuli and the context in which they occur. Another interpretation is that they play a central role in learning and memory. Anatomical studies suggest that arthropod mushroom bodies are predominately associated with olfactory pathways except in phylogenetically basal insects. The prominent olfactory input to the mushroom body calyces in more recent insect orders is an acquired character. An overview of the history of research on the mushroom bodies, as well as comparative and evolutionary considerations, provides a conceptual framework for discussing the roles of these neuropils.

One of the principal bottlenecks in applying learning techniques to classification problems is the large amount of labeled training data required. Especially for images and video, providing training data is very expensive in terms of human time and effort. In this paper we propose an active learning approach to tackle the problem. Instead of passively accepting random training examples, the active learning algorithm iteratively selects unlabeled examples for the user to label, so that human effort is focused on labeling the most “useful” examples. Our method relies on the idea of uncertainty sampling, in which the algorithm selects unlabeled examples that it finds hardest to classify. Specifically, we propose an uncertainty measure that generalizes margin-based uncertainty to the multi-class case and is easy to compute, so that active learning can handle a large number of classes and large data sizes efficiently. We demonstrate results for letter and digit recognition on datasets from the UCI repository, object recognition results on the Caltech-101 dataset, and scene categorization results on a dataset of 13 natural scene categories. The proposed method gives large reductions in the number of training examples required over random selection to achieve similar classification accuracy, with little computational overhead.

The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) Global Digital Elevation Model (GDEM) was released to the public in My 2009. The GDEM version 2, currently under development, is reproduced using an updated algorithm and contains new ASTER data observed after September 2008. Validation study of the trial and beta version of GDEM version 2 was carried out to investigate its characteristics such as geolocation error, elevation error and horizontal resolution. The results of the study confirmed that elevation offset and horizontal resolution will be greatly improved in version 2 and the enhanced horizontal resolution will serve to reduce the standard deviation of elevation and geolocation error.

•A mouse model developed that recapitulates the progressive stages of human fatty liver disease. •The functional pathways of gene expression and immune abnormalities in this model closely resemble human disease. •The ease and reproducibility of this model makes it ideal to study disease pathogenesis and test new treatments. Background and Aims Although the majority of patients with non-alcoholic fatty liver disease (NAFLD) have only steatosis without progression, a sizeable fraction develop non-alcoholic steatohepatitis (NASH), which can lead to cirrhosis and hepatocellular carcinoma (HCC). Many established diet-induced mouse models for NASH require 24–52 weeks, which makes testing for drug response costly and time consuming. Methods We have sought to establish a murine NASH model with rapid progression of extensive fibrosis and HCC by using a western diet (WD), which is high-fat, high-fructose and high-cholesterol, combined with low weekly dose of intraperitoneal carbon tetrachloride (CCl4), which serves as an accelerator. Results C57BL/6J mice were fed a normal chow diet ± CCl4 or WD ± CCl4 for 12 and 24 weeks. Addition of CCl4 exacerbated histological features of NASH, fibrosis, and tumor development induced by WD, which resulted in stage 3 fibrosis at 12 weeks and HCC development at 24 weeks. Furthermore, whole liver transcriptomic analysis indicated that dysregulated molecular pathways in WD/CCl4 mice and immunologic features were similar to those of human NASH. Conclusions Our mouse NASH model exhibits rapid progression of advanced fibrosis and HCC, and mimics histological, immunological and transcriptomic features of human NASH, suggesting that it will be a useful experimental tool for preclinical drug testing. Lay summary A carefully characterized model has been developed in mice that recapitulates the progressive stages of human fatty liver disease, from simple steatosis, to inflammation, fibrosis and cancer. The functional pathways of gene expression and immune abnormalities in this model closely resemble human disease. The ease and reproducibility of this model make it ideal to study disease pathogenesis and test new treatments. Although the majority of patients with non-alcoholic fatty liver disease (NAFLD) have only steatosis without progression, a sizeable fraction develop non-alcoholic steatohepatitis (NASH), which can lead to cirrhosis and hepatocellular carcinoma (HCC). Many established diet-induced mouse models for NASH require 24–52 weeks, which makes testing for drug response costly and time consuming. We have sought to establish a murine NASH model with rapid progression of extensive fibrosis and HCC by using a western diet (WD), which is high-fat, high-fructose and high-cholesterol, combined with low weekly dose of intraperitoneal carbon tetrachloride (CCl4), which serves as an accelerator. C57BL/6J mice were fed a normal chow diet ± CCl4 or WD ± CCl4 for 12 and 24 weeks. Addition of CCl4 exacerbated histological features of NASH, fibrosis, and tumor development induced by WD, which resulted in stage 3 fibrosis at 12 weeks and HCC development at 24 weeks. Furthermore, whole liver transcriptomic analysis indicated that dysregulated molecular pathways in WD/CCl4 mice and immunologic features were similar to those of human NASH. Our mouse NASH model exhibits rapid progression of advanced fibrosis and HCC, and mimics histological, immunological and transcriptomic features of human NASH, suggesting that it will be a useful experimental tool for preclinical drug testing.

Silver nanoparticles were produced by laser ablation of a metal silver plate in aqueous solutions of surfactants, C n H2 n +1SO4Na (n = 8, 10, 12, 16). The nanoparticles thus produced were characterized by electron microscopy and UV−visible absorption spectroscopy. The abundances of the nanoparticles before and after centrifugation were measured as a function of the surfactant concentration. The concentration dependence of the abundance implies that the surfactant coverage and the charge state on the nanoparticle surface are closely related to the stability of the nanoparticles in the solutions. The nanoparticles tend to be aggregated when the coverage is less than unity, while they are very stable when the surface is covered with a double layer of the surfactant molecules.

All six minichromosome maintenance (MCM) proteins have DNA-dependent ATPase motifs in the central domain which is conserved from yeast to mammals. Our group purified MCM protein complexes consisting of MCM2, -4 (Cdc21), -6 (Mis5), and -7 (CDC47) proteins from HeLa cells by using histone-Sepharose column chromatography (Ishimi, Y., Ichinose, S., Omori, A., Sato K., and Kimura, H. (1996) J. Biol. Chem. 271, 24115–24122). The present study revealed that both ATPase activity and DNA helicase activity that displaces oligonucleotides annealed to single-stranded circular DNA are associated with an MCM protein complex. Both ATPase and DNA helicase activities were co-purified with a 600-kDa protein complex that is consisted of equal amounts of MCM4, -6, and -7 proteins. An immunodepletion of the MCM protein complex from the purified fraction using anti-MCM4 antibody resulted in the severe reduction of the DNA helicase activity. Displacement of DNA fragments by the DNA helicase suggested that it migrated along single-stranded DNA in the 3′ to 5′ direction, and the DNA helicase activity was detected only in the presence of hydrolyzable ATP or dATP. These results suggest that this helicase may be involved in the initiation of DNA replication as a DNA unwinding enzyme. All six minichromosome maintenance (MCM) proteins have DNA-dependent ATPase motifs in the central domain which is conserved from yeast to mammals. Our group purified MCM protein complexes consisting of MCM2, -4 (Cdc21), -6 (Mis5), and -7 (CDC47) proteins from HeLa cells by using histone-Sepharose column chromatography (Ishimi, Y., Ichinose, S., Omori, A., Sato K., and Kimura, H. (1996) J. Biol. Chem. 271, 24115–24122). The present study revealed that both ATPase activity and DNA helicase activity that displaces oligonucleotides annealed to single-stranded circular DNA are associated with an MCM protein complex. Both ATPase and DNA helicase activities were co-purified with a 600-kDa protein complex that is consisted of equal amounts of MCM4, -6, and -7 proteins. An immunodepletion of the MCM protein complex from the purified fraction using anti-MCM4 antibody resulted in the severe reduction of the DNA helicase activity. Displacement of DNA fragments by the DNA helicase suggested that it migrated along single-stranded DNA in the 3′ to 5′ direction, and the DNA helicase activity was detected only in the presence of hydrolyzable ATP or dATP. These results suggest that this helicase may be involved in the initiation of DNA replication as a DNA unwinding enzyme. There are at least six MCM 1The abbreviations used are: MCM, minichromosome maintenance; DTT, dithiothreitol; DSP, dithiobis-succinimidyl propionate; ATPγS, adenosine 5′-O-(thiotriphosphate); ORC, origin recognition complex; AMP-PNP, β-γ-imidoadenosine-5′-triphosphate; RLF, replication licensing factor.1The abbreviations used are: MCM, minichromosome maintenance; DTT, dithiothreitol; DSP, dithiobis-succinimidyl propionate; ATPγS, adenosine 5′-O-(thiotriphosphate); ORC, origin recognition complex; AMP-PNP, β-γ-imidoadenosine-5′-triphosphate; RLF, replication licensing factor. proteins that play an essential role in eukaryotic DNA replication as follows: MCM2, -3, -4 (Cdc21), -5, -6 (Mis5), and -7 (CDC47) proteins (see reviews in Refs.1Tye B.-K. Trends Cell Biol. 1994; 4: 160-166Abstract Full Text PDF PubMed Scopus (108) Google Scholar, 2Chong J.P.J. Thömmes P. Blow J.J. Trends Biochem. Sci. 1996; 21: 102-106Abstract Full Text PDF PubMed Scopus (156) Google Scholar, 3Kearsey S.E. Mariorano D. Holmes E.C. Todorov I.T. BioEssay. 1996; 18: 183-190Crossref PubMed Scopus (120) Google Scholar). Genetic evidence suggests that these proteins are required for the initiation of DNA replication in yeast (4Hennessy K.M. Lee A. Chen E. Botstein D. Genes Dev. 1991; 5: 958-969Crossref PubMed Scopus (229) Google Scholar, 5Mariorano D. Blom van Assendelft G. Kearsey S.E. EMBO J. 1996; 15: 861-872Crossref PubMed Scopus (83) Google Scholar). The inactivation of human MCM2 protein with antibody consistently inhibits the initiation of DNA replication (6Todorov I.T. Pepperkok R. Philipova R.N. Kearsey S.E. Ansorge W. Werner D. J. Cell Sci. 1994; 107: 253-265Crossref PubMed Google Scholar). Interaction between the MCM proteins has been reported in yeast (4Hennessy K.M. Lee A. Chen E. Botstein D. Genes Dev. 1991; 5: 958-969Crossref PubMed Scopus (229) Google Scholar, 7Yan H. Gibson S. Tye B.K. Genes Dev. 1991; 5: 944-957Crossref PubMed Scopus (152) Google Scholar), and the protein complexes containing MCM proteins are detected in Drosophila (8Su T.T. Feger G. O'Farrell P.H. Mol. Biol. Cell. 1996; 7: 319-326Crossref PubMed Scopus (48) Google Scholar), Xenopus(9Hendrickson M. Madine M. Dalton S. Gautier J. Proc. Natl. Acad. Sci. U. S. A. 1996; 93: 12223-12228Crossref PubMed Scopus (104) Google Scholar), mouse (10Kimura H. Takizawa N. Nozaki N. Sugimoto K. Nucleic Acids Res. 1995; 23: 2097-2104Crossref PubMed Scopus (67) Google Scholar, 11Kimura H. Ohtomo T. Yamaguchi M. Ishi A. Sugimoto K. Genes to Cells. 1996; 1: PubMed Scopus Google Scholar), and human cells D. R. R. J. Biochem. 1995; PubMed Scopus Google Scholar, R. D. R. J. Biochem. 1995; PubMed Scopus Google Scholar, M. T. M. J. Biol. Chem. Full Text Full Text PDF PubMed Scopus Google Scholar). human MCM4, -6, and -7 proteins a and MCM2 is associated with this complex D. R. R. J. Biochem. 1995; PubMed Scopus Google Scholar, D. A. R. R. J. Biochem. 1996; PubMed Scopus Google Scholar, H. R. 1996; PubMed Scopus Google Scholar). and proteins a complex (10Kimura H. Takizawa N. Nozaki N. Sugimoto K. Nucleic Acids Res. 1995; 23: 2097-2104Crossref PubMed Scopus (67) Google Scholar, R. D. R. J. Biochem. 1995; PubMed Scopus Google Scholar). All six of the MCM proteins DNA-dependent ATPase motifs in a central domain that is conserved from yeast to and these motifs are in that the DNA Nucleic Acids Res. 21: PubMed Scopus Google Scholar). These suggest that MCM protein complexes may be involved in the initiation of DNA replication as an that DNA in the origin DNA helicase activity of MCM proteins has been proteins with the initiation of DNA replication and are from the as DNA replication I.T. A. Kearsey S.E. J. Cell Biol. 1995; PubMed Scopus Google Scholar, H. Tye B.K. Genes Dev. 7: PubMed Scopus Google Scholar, Biol. 1995; 5: Full Text Full Text PDF PubMed Scopus Google Scholar). Our group that MCM protein complexes containing MCM2, -6, and -7 proteins with and were purified to by histone-Sepharose column chromatography S. A. Sato K. H. J. Biol. Chem. 1996; Full Text Full Text PDF PubMed Scopus Google Scholar). the present it is that both ATPase and DNA helicase activities are associated with an MCM4, -6, and -7 protein that both ATPase and DNA helicase activities were present in the purified MCM protein The results of the immunodepletion using anti-MCM4 antibody suggested that the DNA helicase activity required the MCM protein complexes The of DNA helicase activity was detected at a of in the equal amounts of MCM4, -6, and -7 proteins were that a complex of MCM4, -6, and -7 is has the DNA helicase activity and it was suggested that or protein was of ATP The protein of the that these MCM proteins a of and the between the of this 600-kDa complex and the DNA helicase activity suggests that this complex as a DNA is that MCM4, -6, and -7 proteins a complex and that this complex with to a complex. The complex may be complexes of MCM proteins in the and was detected at a MCM proteins were the a complex was detected These results suggest that of MCM proteins are present in purified MCM proteins and that to of as a DNA DNA helicase activity was detected only in the MCM2 it is that the presence of MCM2 protein the of MCM4, -6, and -7 proteins to the DNA helicase MCM proteins of MCM2, -6, and -7 were to a histone-Sepharose column S. A. Sato K. H. J. Biol. Chem. 1996; Full Text Full Text PDF PubMed Scopus Google Scholar). Our group that these only MCM2 protein has an for and H. Kimura, that a complex consisting of MCM2, -6, and -7 was to the histone-Sepharose column the between MCM2 and and a complex of MCM4, -6, and -7 was from MCM2 protein the of the MCM proteins with group D. R. R. J. Biochem. 1995; PubMed Scopus Google Scholar, D. A. R. R. J. Biochem. 1996; PubMed Scopus Google Scholar, H. R. 1996; PubMed Scopus Google has reported that MCM4, -6, and -7 proteins a complex and that MCM2 protein is associated with the of MCM proteins. that a of MCM4, -6, and -7 has DNA helicase activity is with the that J. T. J. J. Biol. Chem. Full Text PDF PubMed Google as a Biochem. 1996; PubMed Scopus Google Scholar, Cell. 1996; Full Text Full Text PDF PubMed Scopus Google Scholar, 1995; PubMed Scopus Google Scholar). a that to MCM proteins has the DNA helicase activity be DNA helicase activity of MCM proteins be from the that of these proteins have motifs that are present in the proteins DNA-dependent ATPase activity Nucleic Acids Res. 21: PubMed Scopus Google Scholar). The DNA helicase activity may be for the initiation as as the of DNA MCM proteins are in the replication are with replication proteins of and replication protein single-stranded or DNA I.T. A. Kearsey S.E. J. Cell Biol. 1995; PubMed Scopus Google Scholar, Biol. 1995; 5: Full Text Full Text PDF PubMed Scopus Google H. Nozaki N. Sugimoto K. EMBO J. 1994; PubMed Scopus Google Scholar, T. R. J. Cell Sci. 1996; PubMed Google Scholar). MCM proteins in at the and from it as the DNA replication I.T. A. Kearsey S.E. J. Cell Biol. 1995; PubMed Scopus Google Scholar, Biol. 1995; 5: Full Text Full Text PDF PubMed Scopus Google Scholar, H. Nozaki N. Sugimoto K. EMBO J. 1994; PubMed Scopus Google Scholar, M. E. K. J. Cell Sci. 1995; Google Scholar). These with suggest that MCM proteins are required at an of the DNA replication as an that DNA in the origin of DNA have been in by the activity that displaces annealed oligonucleotides P. U. PubMed Scopus (48) Google Scholar, BioEssay. 1994; PubMed Scopus Google Scholar). a mouse DNA helicase M. T. T. S. J. T. M. T. Mol. Cell. Biol. 1995; 15: PubMed Scopus Google and Proc. Natl. Acad. Sci. U. S. A. 1995; PubMed Scopus Google are for the involved in the of the replication The complex of MCM4, -6, and -7 proteins is from DNA in that it oligonucleotides the activity of DNA helicase in the fraction was with DNA of the MCM4, -6, and -7 protein complex may the DNA helicase or replication proteins as replication protein may be involved in the of DNA unwinding by the MCM protein complex. is that the DNA helicase activity of MCM proteins is required only at the of DNA unwinding of the origin and DNA the role of MCM proteins in the DNA origin recognition complex consisting of six was in yeast as a complex that the origin PubMed Scopus Google Scholar), and it has been that the is required for DNA replication R. PubMed Scopus Google Scholar, M. P. J. PubMed Scopus Google Scholar, G. A. J. K. J. PubMed Scopus Google Scholar, S. J. R. S. Mol. Biol. Cell. 1995; PubMed Scopus Google Scholar). of A. J.P.J. M. Blow J.J. Cell. 1996; Full Text Full Text PDF PubMed Scopus Google and 1996; PubMed Scopus Google were in and it was that are required for DNA replication in an in between and MCM proteins has been reported in S. S. J. R. S. Mol. Biol. Cell. 1995; PubMed Scopus Google Scholar, J.J. PubMed Scopus Google Scholar). MCM protein complexes may be involved in the initiation of DNA replication as a DNA unwinding by with is that MCM proteins may MCM protein complexes of MCM2, -6, and -7 have a for in which was S. A. Sato K. H. J. Biol. Chem. 1996; Full Text Full Text PDF PubMed Scopus Google Scholar). The that hydrolyzable ATP is required for the DNA helicase activity of MCM proteins with the that ATP is required for DNA replication in the J.P.J. Blow J.J. 1995; PubMed Scopus Google Scholar). this both licensing and are required for DNA has been purified to and of a complex of MCM proteins J.P.J. Blow J.J. 1995; PubMed Scopus Google Scholar, 1995; PubMed Scopus Google Scholar, S. S. H. H. Cell. 1995; Full Text PDF PubMed Scopus Google Scholar). has been suggested that is required for MCM proteins to J.P.J. Blow J.J. 1995; PubMed Scopus Google Scholar). Cell. 1996; Full Text Full Text PDF PubMed Scopus Google have reported that the of and proteins to is required for the of MCM protein with which to the initiation of DNA replication in the the present it was that both ATPase and DNA helicase activities were associated with purified MCM proteins. the of these activities are of MCM4, -6, and -7 protein complex this the evidence for the that MCM protein complexes as a DNA unwinding in the initiation of DNA There are at least six MCM 1The abbreviations used are: MCM, minichromosome maintenance; DTT, dithiothreitol; DSP, dithiobis-succinimidyl propionate; ATPγS, adenosine 5′-O-(thiotriphosphate); ORC, origin recognition complex; AMP-PNP, β-γ-imidoadenosine-5′-triphosphate; RLF, replication licensing factor.1The abbreviations used are: MCM, minichromosome maintenance; DTT, dithiothreitol; DSP, dithiobis-succinimidyl propionate; ATPγS, adenosine 5′-O-(thiotriphosphate); ORC, origin recognition complex; AMP-PNP, β-γ-imidoadenosine-5′-triphosphate; RLF, replication licensing factor. proteins that play an essential role in eukaryotic DNA replication as follows: MCM2, -3, -4 (Cdc21), -5, -6 (Mis5), and -7 (CDC47) proteins (see reviews in Refs.1Tye B.-K. Trends Cell Biol. 1994; 4: 160-166Abstract Full Text PDF PubMed Scopus (108) Google Scholar, 2Chong J.P.J. Thömmes P. Blow J.J. Trends Biochem. Sci. 1996; 21: 102-106Abstract Full Text PDF PubMed Scopus (156) Google Scholar, 3Kearsey S.E. Mariorano D. Holmes E.C. Todorov I.T. BioEssay. 1996; 18: 183-190Crossref PubMed Scopus (120) Google Scholar). Genetic evidence suggests that these proteins are required for the initiation of DNA replication in yeast (4Hennessy K.M. Lee A. Chen E. Botstein D. Genes Dev. 1991; 5: 958-969Crossref PubMed Scopus (229) Google Scholar, 5Mariorano D. Blom van Assendelft G. Kearsey S.E. EMBO J. 1996; 15: 861-872Crossref PubMed Scopus (83) Google Scholar). The inactivation of human MCM2 protein with antibody consistently inhibits the initiation of DNA replication (6Todorov I.T. Pepperkok R. Philipova R.N. Kearsey S.E. Ansorge W. Werner D. J. Cell Sci. 1994; 107: 253-265Crossref PubMed Google Scholar). Interaction between the MCM proteins has been reported in yeast (4Hennessy K.M. Lee A. Chen E. Botstein D. Genes Dev. 1991; 5: 958-969Crossref PubMed Scopus (229) Google Scholar, 7Yan H. Gibson S. Tye B.K. Genes Dev. 1991; 5: 944-957Crossref PubMed Scopus (152) Google Scholar), and the protein complexes containing MCM proteins are detected in Drosophila (8Su T.T. Feger G. O'Farrell P.H. Mol. Biol. Cell. 1996; 7: 319-326Crossref PubMed Scopus (48) Google Scholar), Xenopus(9Hendrickson M. Madine M. Dalton S. Gautier J. Proc. Natl. Acad. Sci. U. S. A. 1996; 93: 12223-12228Crossref PubMed Scopus (104) Google Scholar), mouse (10Kimura H. Takizawa N. Nozaki N. Sugimoto K. Nucleic Acids Res. 1995; 23: 2097-2104Crossref PubMed Scopus (67) Google Scholar, 11Kimura H. Ohtomo T. Yamaguchi M. Ishi A. Sugimoto K. Genes to Cells. 1996; 1: PubMed Scopus Google Scholar), and human cells D. R. R. J. Biochem. 1995; PubMed Scopus Google Scholar, R. D. R. J. Biochem. 1995; PubMed Scopus Google Scholar, M. T. M. J. Biol. Chem. Full Text Full Text PDF PubMed Scopus Google Scholar). human MCM4, -6, and -7 proteins a and MCM2 is associated with this complex D. R. R. J. Biochem. 1995; PubMed Scopus Google Scholar, D. A. R. R. J. Biochem. 1996; PubMed Scopus Google Scholar, H. R. 1996; PubMed Scopus Google Scholar). and proteins a complex (10Kimura H. Takizawa N. Nozaki N. Sugimoto K. Nucleic Acids Res. 1995; 23: 2097-2104Crossref PubMed Scopus (67) Google Scholar, R. D. R. J. Biochem. 1995; PubMed Scopus Google Scholar). All six of the MCM proteins DNA-dependent ATPase motifs in a central domain that is conserved from yeast to and these motifs are in that the DNA Nucleic Acids Res. 21: PubMed Scopus Google Scholar). These suggest that MCM protein complexes may be involved in the initiation of DNA replication as an that DNA in the origin DNA helicase activity of MCM proteins has been MCM proteins with the initiation of DNA replication and are from the as DNA replication I.T. A. Kearsey S.E. J. Cell Biol. 1995; PubMed Scopus Google Scholar, H. Tye B.K. Genes Dev. 7: PubMed Scopus Google Scholar, Biol. 1995; 5: Full Text Full Text PDF PubMed Scopus Google Scholar). Our group that MCM protein complexes containing MCM2, -6, and -7 proteins with and were purified to by histone-Sepharose column chromatography S. A. Sato K. H. J. Biol. Chem. 1996; Full Text Full Text PDF PubMed Scopus Google Scholar). the present it is that both ATPase and DNA helicase activities are associated with an MCM4, -6, and -7 protein complex. that both ATPase and DNA helicase activities were present in the purified MCM protein The results of the immunodepletion using anti-MCM4 antibody suggested that the DNA helicase activity required the MCM protein complexes The of DNA helicase activity was detected at a of in the equal amounts of MCM4, -6, and -7 proteins were that a complex of MCM4, -6, and -7 is has the DNA helicase activity and it was suggested that or protein was of ATP The protein of the that these MCM proteins a of and the between the of this 600-kDa complex and the DNA helicase activity suggests that this complex as a DNA is that MCM4, -6, and -7 proteins a complex and that this complex with to a complex. The complex may be complexes of MCM proteins in the and was detected at a MCM proteins were the a complex was detected These results suggest that of MCM proteins are present in purified MCM proteins and that to of as a DNA DNA helicase activity was detected only in the MCM2 it is that the presence of MCM2 protein the of MCM4, -6, and -7 proteins to the DNA helicase MCM proteins of MCM2, -6, and -7 were to a histone-Sepharose column S. A. Sato K. H. J. Biol. Chem. 1996; Full Text Full Text PDF PubMed Scopus Google Scholar). Our group that these only MCM2 protein has an for and H. Kimura, that a complex consisting of MCM2, -6, and -7 was to the histone-Sepharose column the between MCM2 and and a complex of MCM4, -6, and -7 was from MCM2 protein the of the MCM proteins with group D. R. R. J. Biochem. 1995; PubMed Scopus Google Scholar, D. A. R. R. J. Biochem. 1996; PubMed Scopus Google Scholar, H. R. 1996; PubMed Scopus Google has reported that MCM4, -6, and -7 proteins a complex and that MCM2 protein is associated with the of MCM proteins. that a of MCM4, -6, and -7 has DNA helicase activity is with the that J. T. J. J. Biol. Chem. Full Text PDF PubMed Google as a Biochem. 1996; PubMed Scopus Google Scholar, Cell. 1996; Full Text Full Text PDF PubMed Scopus Google Scholar, 1995; PubMed Scopus Google Scholar). a that to MCM proteins has the DNA helicase activity be DNA helicase activity of MCM proteins be from the that of these proteins have motifs that are present in the proteins DNA-dependent ATPase activity Nucleic Acids Res. 21: PubMed Scopus Google Scholar). The DNA helicase activity may be for the initiation as as the of DNA MCM proteins are in the replication are with replication proteins of and replication protein single-stranded or DNA I.T. A. Kearsey S.E. J. Cell Biol. 1995; PubMed Scopus Google Scholar, Biol. 1995; 5: Full Text Full Text PDF PubMed Scopus Google H. Nozaki N. Sugimoto K. EMBO J. 1994; PubMed Scopus Google Scholar, T. R. J. Cell Sci. 1996; PubMed Google Scholar). MCM proteins in at the and from it as the DNA replication I.T. A. Kearsey S.E. J. Cell Biol. 1995; PubMed Scopus Google Scholar, Biol. 1995; 5: Full Text Full Text PDF PubMed Scopus Google Scholar, H. Nozaki N. Sugimoto K. EMBO J. 1994; PubMed Scopus Google Scholar, M. E. K. J. Cell Sci. 1995; Google Scholar). These with suggest that MCM proteins are required at an of the DNA replication as an that DNA in the origin of DNA have been in by the activity that displaces annealed oligonucleotides P. U. PubMed Scopus (48) Google Scholar, BioEssay. 1994; PubMed Scopus Google Scholar). a mouse DNA helicase M. T. T. S. J. T. M. T. Mol. Cell. Biol. 1995; 15: PubMed Scopus Google and Proc. Natl. Acad. Sci. U. S. A. 1995; PubMed Scopus Google are for the involved in the of the replication The complex of MCM4, -6, and -7 proteins is from DNA in that it oligonucleotides the activity of DNA helicase in the fraction was with DNA of the MCM4, -6, and -7 protein complex may the DNA helicase or replication proteins as replication protein may be involved in the of DNA unwinding by the MCM protein complex. is that the DNA helicase activity of MCM proteins is required only at the of DNA unwinding of the origin and DNA the role of MCM proteins in the DNA origin recognition complex consisting of six was in yeast as a complex that the origin PubMed Scopus Google Scholar), and it has been that the is required for DNA replication R. PubMed Scopus Google Scholar, M. P. J. PubMed Scopus Google Scholar, G. A. J. K. J. PubMed Scopus Google Scholar, S. J. R. S. Mol. Biol. Cell. 1995; PubMed Scopus Google Scholar). of A. J.P.J. M. Blow J.J. Cell. 1996; Full Text Full Text PDF PubMed Scopus Google and 1996; PubMed Scopus Google were in and it was that are required for DNA replication in an in between and MCM proteins has been reported in S. S. J. R. S. Mol. Biol. Cell. 1995; PubMed Scopus Google Scholar, J.J. PubMed Scopus Google Scholar). MCM protein complexes may be involved in the initiation of DNA replication as a DNA unwinding by with is that MCM proteins may MCM protein complexes of MCM2, -6, and -7 have a for in which was S. A. Sato K. H. J. Biol. Chem. 1996; Full Text Full Text PDF PubMed Scopus Google Scholar). The that hydrolyzable ATP is required for the DNA helicase activity of MCM proteins with the that ATP is required for DNA replication in the J.P.J. Blow J.J. 1995; PubMed Scopus Google Scholar). this both licensing and are required for DNA has been purified to and of a complex of MCM proteins J.P.J. Blow J.J. 1995; PubMed Scopus Google Scholar, 1995; PubMed Scopus Google Scholar, S. S. H. H. Cell. 1995; Full Text PDF PubMed Scopus Google Scholar). has been suggested that is required for MCM proteins to J.P.J. Blow J.J. 1995; PubMed Scopus Google Scholar). Cell. 1996; Full Text Full Text PDF PubMed Scopus Google have reported that the of and proteins to is required for the of MCM protein with which to the initiation of DNA replication in the the present it was that both ATPase and DNA helicase activities were associated with purified MCM proteins. the of these activities are of MCM4, -6, and -7 protein complex this the evidence for the that MCM protein complexes as a DNA unwinding in the initiation of DNA that both ATPase and DNA helicase activities were present in the purified MCM protein The results of the immunodepletion using anti-MCM4 antibody suggested that the DNA helicase activity required the MCM protein complexes The of DNA helicase activity was detected at a of in the equal amounts of MCM4, -6, and -7 proteins were that a complex of MCM4, -6, and -7 is has the DNA helicase activity and it was suggested that or protein was of ATP The protein of the that these MCM proteins a of and the between the of this 600-kDa complex and the DNA helicase activity suggests that this complex as a DNA is that MCM4, -6, and -7 proteins a complex and that this complex with to a complex. The complex may be complexes of MCM proteins in the and was detected at a MCM proteins were the a complex was detected These results suggest that of MCM proteins are present in purified MCM proteins and that to of as a DNA DNA helicase activity was detected only in the MCM2 it is that the presence of MCM2 protein the of MCM4, -6, and -7 proteins to the DNA helicase activity. The MCM proteins of MCM2, -6, and -7 were to a histone-Sepharose column S. A. Sato K. H. J. Biol. Chem. 1996; Full Text Full Text PDF PubMed Scopus Google Scholar). Our group that these only MCM2 protein has an for and H. Kimura, that a complex consisting of MCM2, -6, and -7 was to the histone-Sepharose column the between MCM2 and and a complex of MCM4, -6, and -7 was from MCM2 protein the of the MCM proteins with group D. R. R. J. Biochem. 1995; PubMed Scopus Google Scholar, D. A. R. R. J. Biochem. 1996; PubMed Scopus Google Scholar, H. R. 1996; PubMed Scopus Google has reported that MCM4, -6, and -7 proteins a complex and that MCM2 protein is associated with the of MCM proteins. that a of MCM4, -6, and -7 has DNA helicase activity is with the that J. T. J. J. Biol. Chem. Full Text PDF PubMed Google as a Biochem. 1996; PubMed Scopus Google Scholar, Cell. 1996; Full Text Full Text PDF PubMed Scopus Google Scholar, 1995; PubMed Scopus Google Scholar). a that to MCM proteins has the DNA helicase activity be The DNA helicase activity of MCM proteins be from the that of these proteins have motifs that are present in the proteins DNA-dependent ATPase activity Nucleic Acids Res. 21: PubMed Scopus Google Scholar). The DNA helicase activity may be for the initiation as as the of DNA MCM proteins are in the replication are with replication proteins of and replication protein single-stranded or DNA I.T. A. Kearsey S.E. J. Cell Biol. 1995; PubMed Scopus Google Scholar, Biol. 1995; 5: Full Text Full Text PDF PubMed Scopus Google H. Nozaki N. Sugimoto K. EMBO J. 1994; PubMed Scopus Google Scholar, T. R. J. Cell Sci. 1996; PubMed Google Scholar). MCM proteins in at the and from it as the DNA replication I.T. A. Kearsey S.E. J. Cell Biol. 1995; PubMed Scopus Google Scholar, Biol. 1995; 5: Full Text Full Text PDF PubMed Scopus Google Scholar, H. Nozaki N. Sugimoto K. EMBO J. 1994; PubMed Scopus Google Scholar, M. E. K. J. Cell Sci. 1995; Google Scholar). These with suggest that MCM proteins are required at an of the DNA replication as an that DNA in the origin of DNA have been in by the activity that displaces annealed oligonucleotides P. U. PubMed Scopus (48) Google Scholar, BioEssay. 1994; PubMed Scopus Google Scholar). a mouse DNA helicase M. T. T. S. J. T. M. T. Mol. Cell. Biol. 1995; 15: PubMed Scopus Google and Proc. Natl. Acad. Sci. U. S. A. 1995; PubMed Scopus Google are for the involved in the of the replication The complex of MCM4, -6, and -7 proteins is from DNA in that it oligonucleotides the activity of DNA helicase in the fraction was with DNA of the MCM4, -6, and -7 protein complex may the DNA helicase or replication proteins as replication protein may be involved in the of DNA unwinding by the MCM protein complex. is that the DNA helicase activity of MCM proteins is required only at the of DNA unwinding of the origin and DNA the role of MCM proteins in the DNA The origin recognition complex consisting of six was in yeast as a complex that the origin PubMed Scopus Google Scholar), and it has been that the is required for DNA replication R. PubMed Scopus Google Scholar, M. P. J. PubMed Scopus Google Scholar, G. A. J. K. J. PubMed Scopus Google Scholar, S. J. R. S. Mol. Biol. Cell. 1995; PubMed Scopus Google Scholar). of A. J.P.J. M. Blow J.J. Cell. 1996; Full Text Full Text PDF PubMed Scopus Google and 1996; PubMed Scopus Google were in and it was that are required for DNA replication in an in between and MCM proteins has been reported in S. S. J. R. S. Mol. Biol. Cell. 1995; PubMed Scopus Google Scholar, J.J. PubMed Scopus Google Scholar). MCM protein complexes may be involved in the initiation of DNA replication as a DNA unwinding by with is that MCM proteins may MCM protein complexes of MCM2, -6, and -7 have a for in which was S. A. Sato K. H. J. Biol. Chem. 1996; Full Text Full Text PDF PubMed Scopus Google Scholar). The that hydrolyzable ATP is required for the DNA helicase activity of MCM proteins with the that ATP is required for DNA replication in the J.P.J. Blow J.J. 1995; PubMed Scopus Google Scholar). this both licensing and are required for DNA has been purified to and of a complex of MCM proteins J.P.J. Blow J.J. 1995; PubMed Scopus Google Scholar, 1995; PubMed Scopus Google Scholar, S. S. H. H. Cell. 1995; Full Text PDF PubMed Scopus Google Scholar). has been suggested that is required for MCM proteins to J.P.J. Blow J.J. 1995; PubMed Scopus Google Scholar). Cell. 1996; Full Text Full Text PDF PubMed Scopus Google have reported that the of and proteins to is required for the of MCM protein with which to the initiation of DNA replication in the the present it was that both ATPase and DNA helicase activities were associated with purified MCM proteins. the of these activities are of MCM4, -6, and -7 protein complex this the evidence for the that MCM protein complexes as a DNA unwinding in the initiation of DNA for the anti-MCM4 antibody and for for mouse DNA helicase for in ATPase and for for the DNA helicase activity is associated with an MCM4, -6, and -7 protein of The of The in a of DTT, of and of MCM proteins purified by or DNA PDF