Search results for "homology"
showing 10 items of 770 documents
Blow-up of the non-equivariant 2+1 dimensional wave map
2014
It has been known for a long time that the equivariant 2+1 wave map into the 2-sphere blows up if the initial data are chosen appropriately. Here, we present numerical evidence for the stability of the blow-up phenomenon under explicit violations of equivariance.
CHEVALLEY COHOMOLOGY FOR KONTSEVICH'S GRAPHS
2005
We introduce the Chevalley cohomology for the graded Lie algebra of polyvector fields on $R^d$. This cohomology occurs naturally in the problem of construction and classification of fomalities on the sapce $ R^d$. Considering only graphs formalities, we define the Chevalley cohomology directly on spaces of graphs. We obtain some simple expressions for the Chevalley coboundary operator and we give examples and applications.
SPECTRAL INVARIANCE FOR CERTAIN ALGEBRAS OF PSEUDODIFFERENTIAL OPERATORS
2001
We construct algebras of pseudodifferential operators on a continuous family groupoid G that are closed under holomorphic functional calculus, contain the algebra of all pseudodifferential operators of order 0 on G as a dense subalgebra, and reflect the smooth structure of the groupoid G, when G is smooth. As an application, we get a better understanding on the structure of inverses of elliptic pseudodifferential operators on classes of non-compact manifolds. For the construction of these algebras closed under holomorphic functional calculus, we develop three methods: one using two-sided semi-ideals, one using commutators, and one based on Schwartz spaces on the groupoid.
Cohomology and associated deformations for not necessarily co-associative bialgebras
1992
In this Letter, a cohomology and an associated theory of deformations for (not necessarily co-associative) bialgebras are studied. The cohomology was introduced in a previous paper (Lett. Math. Phys.25, 75–84 (1992)). This theory has several advantages, especially in calculating cohomology spaces and in its adaptability to deformations of quasi-co-associative (qca) bialgebras and even quasi-triangular qca bialgebras.
Cloning of Two Putative Ecdysteroid Receptor Isoforms from Tenebrio Molitor and their Developmental Expression in the Epidermis during Metamorphosis
1997
Using the Drosophila EcR-B1 cDNA as a probe, we have cloned the putative ecdysteroid receptor from the mealworm Tenebrio molitor. We have isolated two cDNAs with different 5' termini that contain a complete open reading frame. These two cDNAs encode two proteins with distinct N-terminal regions corresponding to two isoforms. The coleopteran receptor is obviously related to the ecdysteroid receptor of other insects, but shares only 89% and 61% amino acid identities with the DNA-binding and ligand-binding domains of the Drosophila receptor, respectively. Its expression pattern has been examined in the epidermis during the last larval instar and pupal stage of T. molitor, in correlation with t…
Glial expression of Swiss cheese (SWS), the Drosophila orthologue of neuropathy target esterase (NTE), is required for neuronal ensheathment and func…
2016
ABSTRACT Mutations in Drosophila Swiss cheese (SWS) or its vertebrate orthologue neuropathy target esterase (NTE), respectively, cause progressive neuronal degeneration in Drosophila and mice and a complex syndrome in humans that includes mental retardation, spastic paraplegia and blindness. SWS and NTE are widely expressed in neurons but can also be found in glia; however, their function in glia has, until now, remained unknown. We have used a knockdown approach to specifically address SWS function in glia and to probe for resulting neuronal dysfunctions. This revealed that loss of SWS in pseudocartridge glia causes the formation of multi-layered glial whorls in the lamina cortex, the firs…
Evolutionary conservation of the structural, pharmacological, and genomic characteristics of the melanocortin receptor subtypes
2005
We have cloned melanocortin receptors (MCRs) from several species of fish. The MC4R and MC5R subtypes arose early in vertebrate evolution and their primary structure is remarkably conserved. Expression and pharmacological characterization of the MCRs in fish has revealed that they bind and respond to melanocortin peptides with high potency. Detailed characterization of the binding properties of the different subtypes suggests that MCRs in early vertebrates had preference for adrenocorticotropic hormone (ACTH) peptides, while the high sensitivity for the shorter proopiomelanocortin (POMC) products, such as the alpha-, beta-, and gamma-melanocyte-stimulating hormone (MSH), has appeared later,…
Active Fragments from Pro- and Antiapoptotic BCL-2 Proteins Have Distinct Membrane Behavior Reflecting Their Functional Divergence
2010
International audience; BACKGROUND:The BCL-2 family of proteins includes pro- and antiapoptotic members acting by controlling the permeabilization of mitochondria. Although the association of these proteins with the outer mitochondrial membrane is crucial for their function, little is known about the characteristics of this interaction.METHODOLOGY/PRINCIPAL FINDINGS:Here, we followed a reductionist approach to clarify to what extent membrane-active regions of homologous BCL-2 family proteins contribute to their functional divergence. Using isolated mitochondria as well as model lipid Langmuir monolayers coupled with Brewster Angle Microscopy, we explored systematically and comparatively the…
Origin of metazoan stem cell system in sponges: first approach to establish the model (Suberites domuncula).
2003
Abstract It is established that Porifera (sponges) represent the earliest phylum which branched off from the common ancestor of all multicellular animals, the Urmetazoa. In the present study, the hypothesis is tested if, during this transition, pluripotent stem cells were formed which are provided—similar to the totipotent cells (archaeocytes/germ cells)—with a self-renewal capacity. As a model system, primmorphs from the sponge Suberites domuncula were used. These 3D-cell aggregates were cultivated in medium (RPMI 1640/seawater) either lacking silicate and ferric iron or in medium which was supplemented with these ‘morphogenetic’ factors. As molecular markers for the potential existence of…
Genes and derived amino acid sequences of S-layer proteins from mesophilic, thermophilic, and extremely thermophilic methanococci
2002
Cells of methanococci are covered by a single layer of protein subunits (S-layer) in hexagonal arrangement, which are directly exposed to the environment and which cannot be stabilized by cellular components. We have isolated S-layer proteins from cells of Methanococcus vannielii ( T(opt.)=37 degrees C), Methanococcus thermolithotrophicus ( T(opt.)=65 degrees C), and Methanococcus jannaschii ( T(opt.)=85 degrees C). The primary structure of the S-layer proteins was determined by sequencing the corresponding genes. According to the predicted amino acid sequence, the molecular masses of the S-layer proteins of the different methanococci are in a small range between 59,064 and 60,547 Da. Compa…