Exogenous HIV-1 Nef upsets the IFN-γ-induced impairment of human intestinal epithelial integrity.

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Maria Giovanna Quaranta

Full Text Available The mucosal tissues play a central role in the transmission of HIV-1 infection as well as in the pathogenesis of AIDS. Despite several clinical studies reported intestinal dysfunction during HIV infection, the mechanisms underlying HIV-induced impairments of mucosal epithelial barrier are still unclear. It has been postulated that HIV-1 alters enterocytic function and HIV-1 proteins have been detected in several cell types of the intestinal mucosa. In the present study, we analyzed the effect of the accessory HIV-1 Nef protein on human epithelial cell line.We used unstimulated or IFN-γ-stimulated Caco-2 cells, as a model for homeostatic and inflamed gastrointestinal tracts, respectively. We investigated the effect of exogenous recombinant Nef on monolayer integrity analyzing its uptake, transepithelial electrical resistance, permeability to FITC-dextran and the expression of tight junction proteins. Moreover, we measured the induction of proinflammatory mediators. Exogenous Nef was taken up by Caco-2 cells, increased intestinal epithelial permeability and upset the IFN-γ-induced reduction of transepithelial resistance, interfering with tight junction protein expression. Moreover, Nef inhibited IFN-γ-induced apoptosis and up-regulated TNF-α, IL-6 and MIP-3α production by Caco-2 cells while down-regulated IL-10 production. The simultaneous exposure of Caco-2 cells to Nef and IFN-γ did not affect cytokine secretion respect to untreated cells. Finally, we found that Nef counteracted the IFN-γ induced arachidonic acid cascade.Our findings suggest that exogenous Nef, perturbing the IFN-γ-induced impairment of intestinal epithelial cells, could prolong cell survival, thus allowing for accumulation of viral particles. Our results may improve the understanding of AIDS pathogenesis, supporting the discovery of new therapeutic interventions.

Nef enhances HIV-1 infectivity via association with the virus assembly complex

International Nuclear Information System (INIS)

Qi Mingli; Aiken, Christopher

2008-01-01

The HIV-1 accessory protein Nef enhances virus infectivity by facilitating an early post-entry step of infection. Nef acts in the virus producer cell, leading to a beneficial modification to HIV-1 particles. Nef itself is incorporated into HIV-1 particles, where it is cleaved by the viral protease during virion maturation. To probe the role of virion-associated Nef in HIV-1 infection, we generated a fusion protein consisting of the host protein cyclophilin A (CypA) linked to the amino terminus of Nef. The resulting CypA-Nef protein enhanced the infectivity of Nef-defective HIV-1 particles and was specifically incorporated into the virions via association with Gag during particle assembly. Pharmacologic or genetic inhibition of CypA-Nef binding to Gag prevented incorporation of CypA-Nef into virions and inhibited infectivity enhancement. Our results indicate that infectivity enhancement by Nef requires its association with a component of the assembling HIV-1 particle

Nef exosomes isolated from the plasma of individuals with HIV-associated dementia (HAD) can induce Aβ(1-42) secretion in SH-SY5Y neural cells.

Science.gov (United States)

Khan, Mahfuz B; Lang, Michelle J; Huang, Ming-Bo; Raymond, Andrea; Bond, Vincent C; Shiramizu, Bruce; Powell, Michael D

2016-04-01

In the era of combined antiretroviral therapy (CART), many of the complications due to HIV-1 infection have diminished. One exception is HIV-associated neurocognitive disorder (HAND). HAND is a spectrum of disorders in cognitive function that ranges from asymptomatic disease to severe dementia (HAD). The milder form of HAND has actually remained the same or slightly increased in prevalence in the CART era. Even in individuals who have maintained undetectable HIV RNA loads, viral proteins such as Nef and Tat can continue to be expressed. In this report, we show that Nef protein and nef messenger RNA (mRNA) are packaged into exosomes that remain in circulation in patients with HAD. Plasma-derived Nef exosomes from patients with HAD have the ability to interact with the neuroblastoma cell line SH-SY5Y and deliver nef mRNA. The mRNA can induce expression of Nef in target cells and subsequently increase expression and secretion of beta-amyloid (Aβ) and Aβ peptides. Increase secretion of amyloid peptide could contribute to cognitive impairment seen in HAND.

HIV-1 Nef down-modulates C-C and C-X-C chemokine receptors via ubiquitin and ubiquitin-independent mechanism.

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Prabha Chandrasekaran

Full Text Available Human and Simian Immunodeficiency virus (HIV-1, HIV-2, and SIV encode an accessory protein, Nef, which is a pathogenesis and virulence factor. Nef is a multivalent adapter that dysregulates the trafficking of many immune cell receptors, including chemokine receptors (CKRs. Physiological endocytic itinerary of agonist occupied CXCR4 involves ubiquitinylation of the phosphorylated receptor at three critical lysine residues and dynamin-dependent trafficking through the ESCRT pathway into lysosomes for degradation. Likewise, Nef induced CXCR4 degradation was critically dependent on the three lysines in the C-terminal -SSLKILSKGK- motif. Nef directly recruits the HECT domain E3 ligases AIP4 or NEDD4 to CXCR4 in the resting state. This mechanism was confirmed by ternary interactions of Nef, CXCR4 and AIP4 or NEDD4; by reversal of Nef effect by expression of catalytically inactive AIP4-C830A mutant; and siRNA knockdown of AIP4, NEDD4 or some ESCRT-0 adapters. However, ubiquitinylation dependent lysosomal degradation was not the only mechanism by which Nef downregulated CKRs. Agonist and Nef mediated CXCR2 (and CXCR1 degradation was ubiquitinylation independent. Nef also profoundly downregulated the naturally truncated CXCR4 associated with WHIM syndrome and engineered variants of CXCR4 that resist CXCL12 induced internalization via an ubiquitinylation independent mechanism.

Inefficient Nef-mediated downmodulation of CD3 and MHC-I correlates with loss of CD4+T cells in natural SIV infection.

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Michael Schindler

2008-07-01

Full Text Available Recent data suggest that Nef-mediated downmodulation of TCR-CD3 may protect SIVsmm-infected sooty mangabeys (SMs against the loss of CD4+ T cells. However, the mechanisms underlying this protective effect remain unclear. To further assess the role of Nef in nonpathogenic SIV infection, we cloned nef alleles from 11 SIVsmm-infected SMs with high (>500 and 15 animals with low (<500 CD4+ T-cells/microl in bulk into proviral HIV-1 IRES/eGFP constructs and analyzed their effects on the phenotype, activation, and apoptosis of primary T cells. We found that not only efficient Nef-mediated downmodulation of TCR-CD3 but also of MHC-I correlated with preserved CD4+ T cell counts, as well as with high numbers of Ki67+CD4+ and CD8+CD28+ T cells and reduced CD95 expression by CD4+ T cells. Moreover, effective MHC-I downregulation correlated with low proportions of effector and high percentages of naïve and memory CD8+ T cells. We found that T cells infected with viruses expressing Nef alleles from the CD4low SM group expressed significantly higher levels of the CD69, interleukin (IL-2 and programmed death (PD-1 receptors than those expressing Nefs from the CD4high group. SIVsmm Nef alleles that were less active in downmodulating TCR-CD3 were also less potent in suppressing the activation of virally infected T cells and subsequent cell death. However, only nef alleles from a single animal with very low CD4+ T cell counts rendered T cells hyper-responsive to activation, similar to those of HIV-1. Our data suggest that Nef may protect the natural hosts of SIV against the loss of CD4+ T cells by at least two mechanisms: (i downmodulation of TCR-CD3 to prevent activation-induced cell death and to suppress the induction of PD-1 that may impair T cell function and survival, and (ii downmodulation of MHC-I to reduce CTL lysis of virally infected CD4+ T cells and/or bystander CD8+ T cell activation.

Structural basis of evasion of cellular adaptive immunity by HIV-1 Nef

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Jia, Xiaofei; Singh, Rajendra; Homann, Stefanie; Yang, Haitao; Guatelli, John; Xiong, Yong (Yale); (VA); (UCSD)

2012-10-24

The HIV-1 protein Nef inhibits antigen presentation by class I major histocompatibility complex (MHC-I). We determined the mechanism of this activity by solving the crystal structure of a protein complex comprising Nef, the MHC-I cytoplasmic domain (MHC-I CD) and the {mu}1 subunit of the clathrin adaptor protein complex 1. A ternary, cooperative interaction clamps the MHC-I CD into a narrow binding groove at the Nef-{mu}1 interface, which encompasses the cargo-recognition site of {mu}1 and the proline-rich strand of Nef. The Nef C terminus induces a previously unobserved conformational change in {mu}1, whereas the N terminus binds the Nef core to position it optimally for complex formation. Positively charged patches on {mu}1 recognize acidic clusters in Nef and MHC-I. The structure shows how Nef functions as a clathrin-associated sorting protein to alter the specificity of host membrane trafficking and enable viral evasion of adaptive immunity.

Amplitude chimeras and chimera death in dynamical networks

International Nuclear Information System (INIS)

Zakharova, Anna; Kapeller, Marie; Schöll, Eckehard

2016-01-01

We find chimera states with respect to amplitude dynamics in a network of Stuart- Landau oscillators. These partially coherent and partially incoherent spatio-temporal patterns appear due to the interplay of nonlocal network topology and symmetry-breaking coupling. As the coupling range is increased, the oscillations are quenched, amplitude chimeras disappear and the network enters a symmetry-breaking stationary state. This particular regime is a novel pattern which we call chimera death. It is characterized by the coexistence of spatially coherent and incoherent inhomogeneous steady states and therefore combines the features of chimera state and oscillation death. Additionally, we show two different transition scenarios from amplitude chimera to chimera death. Moreover, for amplitude chimeras we uncover the mechanism of transition towards in-phase synchronized regime and discuss the role of initial conditions. (paper)

The HIV-1 Nef protein and phagocyte NADPH oxidase activation

DEFF Research Database (Denmark)

Vilhardt, Frederik; Plastre, Olivier; Sawada, Makoto

2002-01-01

of Rac by Clostridium difficile toxin B abolished the Nef effect. (ii) The fraction of activated Rac1 was increased in Nef-transduced cells, and (iii) the dominant positive Rac1(V12) mutant mimicked the effect of Nef. These results are to our knowledge the first analysis of the effect of Rac activation...

Regulation of T cell activation by HIV-1 accessory proteins: Vpr acts via distinct mechanisms to cooperate with Nef in NFAT-directed gene expression and to promote transactivation by CREB

International Nuclear Information System (INIS)

Lahti, Anna L.; Manninen, Aki; Saksela, Kalle

2003-01-01

Nef and Vpr are lentiviral accessory proteins that have been implicated in regulation of cellular gene expression. We noticed that Vpr can potentiate Nef-induced activation of nuclear factor of activated T cells (NFAT)-dependent transcription. Unlike Nef, which stimulated calcium signaling to activate NFAT, Vpr functioned farther downstream. Similar to the positive effects of Vpr on most of the transcriptional test systems that we used, potentiation of NFAT-directed gene expression was relatively modest in magnitude (two- to threefold) and depended on the cell cycle-arresting capacity of Vpr. By contrast, we found that Vpr could cause more than fivefold upregulation of cyclic AMP response element (CRE)-directed transcription via a mechanism that did not require Vpr-induced G2/M arrest. This effect, however, was only evident under suboptimal conditions known to lead to serine phosphorylation of the CRE binding factor (CREB) but not to CREB-dependent gene expression. This suggested that Vpr may act by stabilizing interactions with CREB and its transcriptional cofactor CREB binding protein (CBP). Indeed, this effect could be blocked by cotransfection of the adenoviral CBP inhibitor E1A. These results provide additional evidence for cell cycle-independent regulation of gene expression by Vpr and implicate CREB as a potentially important target for Vpr action in HIV-infected host cells

Formation of a unique cluster of G-quadruplex structures in the HIV-1 Nef coding region: implications for antiviral activity.

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Rosalba Perrone

Full Text Available G-quadruplexes are tetraplex structures of nucleic acids that can form in G-rich sequences. Their presence and functional role have been established in telomeres, oncogene promoters and coding regions of the human chromosome. In particular, they have been proposed to be directly involved in gene regulation at the level of transcription. Because the HIV-1 Nef protein is a fundamental factor for efficient viral replication, infectivity and pathogenesis in vitro and in vivo, we investigated G-quadruplex formation in the HIV-1 nef gene to assess the potential for viral inhibition through G-quadruplex stabilization. A comprehensive computational analysis of the nef coding region of available strains showed the presence of three conserved sequences that were uniquely clustered. Biophysical testing proved that G-quadruplex conformations were efficiently stabilized or induced by G-quadruplex ligands in all three sequences. Upon incubation with a G-quadruplex ligand, Nef expression was reduced in a reporter gene assay and Nef-dependent enhancement of HIV-1 infectivity was significantly repressed in an antiviral assay. These data constitute the first evidence of the possibility to regulate HIV-1 gene expression and infectivity through G-quadruplex targeting and therefore open a new avenue for viral treatment.

Natural HIV-1 NEF accelerates virus replication in primary human lymphocytes

NARCIS (Netherlands)

de Ronde, A.; Klaver, B.; Keulen, W.; Smit, L.; Goudsmit, J.

1992-01-01

HIV-1 NEF genes were isolated directly from peripheral blood lymphocyte DNA of two HIV-1-infected individuals and cloned into an HXB-2-infectious molecular clone. The effect of NEF on virus production in T-cell lines and primary human lymphocytes was studied. Naturally occurring NEF accelerates

Proteomic analysis of HIV-1 Nef cellular binding partners reveals a role for exocyst complex proteins in mediating enhancement of intercellular nanotube formation

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Mukerji Joya

2012-06-01

Full Text Available Abstract Background HIV-1 Nef protein contributes to pathogenesis via multiple functions that include enhancement of viral replication and infectivity, alteration of intracellular trafficking, and modulation of cellular signaling pathways. Nef stimulates formation of tunneling nanotubes and virological synapses, and is transferred to bystander cells via these intercellular contacts and secreted microvesicles. Nef associates with and activates Pak2, a kinase that regulates T-cell signaling and actin cytoskeleton dynamics, but how Nef promotes nanotube formation is unknown. Results To identify Nef binding partners involved in Pak2-association dependent Nef functions, we employed tandem mass spectrometry analysis of Nef immunocomplexes from Jurkat cells expressing wild-type Nef or Nef mutants defective for the ability to associate with Pak2 (F85L, F89H, H191F and A72P, A75P in NL4-3. We report that wild-type, but not mutant Nef, was associated with 5 components of the exocyst complex (EXOC1, EXOC2, EXOC3, EXOC4, and EXOC6, an octameric complex that tethers vesicles at the plasma membrane, regulates polarized exocytosis, and recruits membranes and proteins required for nanotube formation. Additionally, Pak2 kinase was associated exclusively with wild-type Nef. Association of EXOC1, EXOC2, EXOC3, and EXOC4 with wild-type, but not mutant Nef, was verified by co-immunoprecipitation assays in Jurkat cells. Furthermore, shRNA-mediated depletion of EXOC2 in Jurkat cells abrogated Nef-mediated enhancement of nanotube formation. Using bioinformatic tools, we visualized protein interaction networks that reveal functional linkages between Nef, the exocyst complex, and the cellular endocytic and exocytic trafficking machinery. Conclusions Exocyst complex proteins are likely a key effector of Nef-mediated enhancement of nanotube formation, and possibly microvesicle secretion. Linkages revealed between Nef and the exocyst complex suggest a new paradigm of

Pervasive transcription read-through promotes aberrant expression of oncogenes and RNA chimeras in renal carcinoma

Science.gov (United States)

Grosso, Ana R; Leite, Ana P; Carvalho, Sílvia; Matos, Mafalda R; Martins, Filipa B; Vítor, Alexandra C; Desterro, Joana MP; Carmo-Fonseca, Maria; de Almeida, Sérgio F

2015-01-01

Aberrant expression of cancer genes and non-canonical RNA species is a hallmark of cancer. However, the mechanisms driving such atypical gene expression programs are incompletely understood. Here, our transcriptional profiling of a cohort of 50 primary clear cell renal cell carcinoma (ccRCC) samples from The Cancer Genome Atlas (TCGA) reveals that transcription read-through beyond the termination site is a source of transcriptome diversity in cancer cells. Amongst the genes most frequently mutated in ccRCC, we identified SETD2 inactivation as a potent enhancer of transcription read-through. We further show that invasion of neighbouring genes and generation of RNA chimeras are functional outcomes of transcription read-through. We identified the BCL2 oncogene as one of such invaded genes and detected a novel chimera, the CTSC-RAB38, in 20% of ccRCC samples. Collectively, our data highlight a novel link between transcription read-through and aberrant expression of oncogenes and chimeric transcripts that is prevalent in cancer. DOI: http://dx.doi.org/10.7554/eLife.09214.001 PMID:26575290

Nonspecific suppressor elements in murine allogeneic radiation chimeras

International Nuclear Information System (INIS)

Urso, P.; Gengozian, N.

1979-01-01

Spleen cells from long-term mouse allogeneic radiation chimeras were tested for their ability to modulate the graft-versus-host (GVH) or plaque-forming cell (PFC) response of normal lymphocytes transplanted in lethally x-irradiated recipients. In vivo GVH proliferation of normal lymphocytes (syngeneic to donor cells of the chimera) against antigens of host-type in which the chimeric state had been established was reduced by chimera cells. Inhibition varied, some chimeras suppressing GVH more than others and a few not suppressing at all. The suppressive effect was abrogated if the chimera cells were treated with anti-THETA; treatment with anti-IgM did not eliminate this activity. When mixtures of normal donor lymphocytes and chimera cells were given to irradiated recipients genetically different from host or donor, reduction of donor cell GVH also occurred. Further, chimera cells reduced the GVH activity of normal host cells in irradiated recipients differing from the host at one H-2 locus and from the donor at minor histocompatibility loci. The modulating effect of spleen cells from chimeras on the PFC response by normal lymphocytes also varied. Six chimeras induced a 25 to 90% suppression, two enhanced the response, and one showed no effect. Where suppression occurred, treatment of chimera cells with anti-THETA most often, but not always, restored PFC production. Our results show that the suppressive action of splenic lymphoid cells by chimeras is highly nonspecific and variable in expression. We suggest that tolerance in chimeras may be mediated by nonspecific suppressor elements leading to unresponsiveness to a variety of antigens including SRBC

Generation of an adenovirus-parvovirus chimera with enhanced oncolytic potential.

Science.gov (United States)

El-Andaloussi, Nazim; Bonifati, Serena; Kaufmann, Johanna K; Mailly, Laurent; Daeffler, Laurent; Deryckère, François; Nettelbeck, Dirk M; Rommelaere, Jean; Marchini, Antonio

2012-10-01

In this study, our goal was to generate a chimeric adenovirus-parvovirus (Ad-PV) vector that combines the high-titer and efficient gene transfer of adenovirus with the anticancer potential of rodent parvovirus. To this end, the entire oncolytic PV genome was inserted into a replication-defective E1- and E3-deleted Ad5 vector genome. As we found that parvoviral NS expression inhibited Ad-PV chimera production, we engineered the parvoviral P4 early promoter, which governs NS expression, by inserting into its sequence tetracycline operator elements. As a result of these modifications, P4-driven expression was blocked in the packaging T-REx-293 cells, which constitutively express the tetracycline repressor, allowing high-yield chimera production. The chimera effectively delivered the PV genome into cancer cells, from which fully infectious replication-competent parvovirus particles were generated. Remarkably, the Ad-PV chimera exerted stronger cytotoxic activities against various cancer cell lines, compared with the PV and Ad parental viruses, while being still innocuous to a panel of tested healthy primary human cells. This Ad-PV chimera represents a novel versatile anticancer agent which can be subjected to further genetic manipulations in order to reinforce its enhanced oncolytic capacity through arming with transgenes or retargeting into tumor cells.

HIV Nef-M1 Effects on Colorectal Cancer Growth in Tumor-induced Spleens and Hepatic Metastasis

Science.gov (United States)

Harrington, Willie; Bond, Vincent; Huang, Ming Bo; Powell, Michael; Lillard, James; Manne, Upender; Bumpers, Harvey

2010-01-01

CXCR4 receptors have been implicated in tumorigenesis and proliferation, making it a potential target for colorectal cancer therapy. Expression of this chemokine receptor on cellular surfaces appears to promote metastasis by directly stimulating tumor cell migration and invasion. The receptor/ligand, CXCR4/SDF-1α, pair are critically important to angiogenesis and vascular remodeling which supports cancer proliferation. Our work has shown that a novel apoptotic peptide of HIV-1, Nef-M1, can act as a CXCR4 antagonist, inducing apoptosis in CXCR4 containing cells. Four colorectal tumor cell lines (HT-29, LS174t, SW480, WiDr), were evaluated for their response to Nef-M1 peptide via in vivo and in vitro. The presence of CXCR4 receptors on tumor cells was determined using immunohistochemical and RT-PCR analyses. Solid xenografts derived from tumor cell lines grown in SCID mice, were evaluated for the persistence of the receptor. Xenografts propagated in SCID mice from each of the four cell lines demonstrated high levels of receptor expression as well. The effects of Nef-M1 in vivo via splenic injected mice and subsequent hepatic metastasis also demonstrated dramatic reduction of primary tumor growth in the spleen and secondary invasion of the liver. We concluded that Nef-M1 peptide, through physical interaction(s) with CXCR4, drives apoptotic reduction in in vivo primary tumor growth and metastasis. PMID:20383296

Differentiation and functional maturation of bone marrow-derived intestinal epithelial T cells expressing membrane T cell receptor in athymic radiation chimeras

International Nuclear Information System (INIS)

Mosley, R.L.; Styre, D.; Klein, J.R.

1990-01-01

The thymus dependency of murine intestinal intraepithelial lymphocytes (IEL) was studied in an athymic F1----parent radiation chimera model. IEL, although not splenic or lymph node lymphocytes, from athymic chimeras displayed normal levels of cells bearing the class-specific T cell Ag, CD4 and CD8; the TCR-associated molecule, CD3; and the Thy-1 Ag. Moreover, two-color flow cytometric analyses of IEL from athymic mice demonstrated regulated expression of T cell Ag characteristic of IEL subset populations from thymus-bearing mice. In immunoprecipitation experiments, surface TCR-alpha beta or TCR-gamma delta were expressed on IEL, although not on splenic lymphocytes, from athymic chimeras. That IEL from athymic chimeras constituted a population of functionally mature effector cells activated in situ, similar to IEL from thymus-bearing mice, was demonstrated by the presence of CD3-mediated lytic activity of athymic lethally irradiated bone marrow reconstituted IEL. These data provide compelling evidence that intestinal T cells do not require thymic influence for maturation and development, and demonstrate that the microenvironment of the intestinal epithelium is uniquely adapted to regulate IEL differentiation

Stress- and sequence-dependent release into the culture medium of HIV-1 Nef produced in Saccharomyces cerevisiae.

Science.gov (United States)

Macreadie, I G; Castelli, L A; Lucantoni, A; Azad, A A

1995-09-11

We have produced human immunodeficiency virus type 1 (HIV-1) Nef (a myristylated 206-amino-acid protein) in Saccharomyces cerevisaie and shown that, while Nef is normally found as a predominantly intracellular protein, amounts up to 40 micrograms/ml of Nef are also released into the extracellular medium during stress. By electrophoretic (SDS-PAGE) analysis the extracellular Nef is indistinguishable from intracellular Nef. Conditions of stress that lead to the release of Nef include elevated levels of copper or magnesium ions or growth at elevated temperatures. This release appears to be dependent upon the N-terminal sequences of Nef, including the presence of a myristylation site. Our observations concerning Nef release in yeast suggest new ways in which the behaviour of Nef should be examined in order to gain further insights into the development of AIDS. If the release of Nef is important in the development of AIDS, our work reveals that Nef-associated symptoms may be reduced or delayed by reducing stresses, such as fevers.

Assessing reprogramming by chimera formation and tetraploid complementation.

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Li, Xin; Xia, Bao-long; Li, Wei; Zhou, Qi

2015-01-01

Pluripotent stem cells can be evaluated by pluripotent markers expression, embryoid body aggregation, teratoma formation, chimera contribution and even more, tetraploid complementation. Whether iPS cells in general are functionally equivalent to normal ESCs is difficult to establish. Here, we present the detailed procedure for chimera formation and tetraploid complementation, the most stringent criterion, to assessing pluripotency.

Smallest chimera states

Science.gov (United States)

Maistrenko, Yuri; Brezetsky, Serhiy; Jaros, Patrycja; Levchenko, Roman; Kapitaniak, Tomasz

2017-01-01

We demonstrate that chimera behavior can be observed in small networks consisting of three identical oscillators, with mutual all-to-all coupling. Three different types of chimeras, characterized by the coexistence of two coherent oscillators and one incoherent oscillator (i.e., rotating with another frequency) have been identified, where the oscillators show periodic (two types) and chaotic (one type) behaviors. Typical bifurcations at the transitions from full synchronization to chimera states and between different types of chimeras have been described. Parameter regions for the chimera states are obtained in the form of Arnold tongues, issued from a singular parameter point. Our analysis suggests that chimera states can be observed in small networks relevant to various real-world systems.

Overlapping effector interfaces define the multiple functions of the HIV-1 Nef polyproline helix

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Kuo Lillian S

2012-05-01

Full Text Available Abstract Background HIV-1 Nef is a multifunctional protein required for full pathogenicity of the virus. As Nef has no known enzymatic activity, it necessarily functions through protein-protein interaction interfaces. A critical Nef protein interaction interface is centered on its polyproline segment (P69VRPQVPLRP78 which contains the helical SH3 domain binding protein motif, PXXPXR. We hypothesized that any Nef-SH3 domain interactions would be lost upon mutation of the prolines or arginine of PXXPXR. Further, mutation of the non-motif “X” residues, (Q73, V74, and L75 would give altered patterns of inhibition for different Nef/SH3 domain protein interactions. Results We found that mutations of either of the prolines or the arginine of PXXPXR are defective for Nef-Hck binding, Nef/activated PAK2 complex formation and enhancement of virion infectivity (EVI. Mutation of the non-motif “X” residues (Q, V and L gave similar patterns of inhibition for Nef/activated PAK2 complex formation and EVI which were distinct from the pattern for Hck binding. These results implicate an SH3 domain containing protein other than Hck for Nef/activated PAK2 complex formation and EVI. We have also mutated Nef residues at the N-and C-terminal ends of the polyproline segment to explore interactions outside of PXXPXR. We discovered a new locus GFP/F (G67, F68, P69 and F90 that is required for Nef/activated PAK2 complex formation and EVI. MHC Class I (MHCI downregulation was only partially inhibited by mutating the PXXPXR motif residues, but was fully inhibited by mutating the C-terminal P78. Further, we observed that MHCI downregulation strictly requires G67 and F68. Our mutational analysis confirms the recently reported structure of the complex between Nef, AP-1 μ1 and the cytoplasmic tail of MHCI, but does not support involvement of an SH3 domain protein in MHCI downregulation. Conclusion Nef has evolved to be dependent on interactions with multiple SH3 domain

Quantum chimera states

International Nuclear Information System (INIS)

Viennot, David; Aubourg, Lucile

2016-01-01

We study a theoretical model of closed quasi-hermitian chain of spins which exhibits quantum analogues of chimera states, i.e. long life classical states for which a part of an oscillator chain presents an ordered dynamics whereas another part presents a disordered dynamics. For the quantum analogue, the chimera behaviour deals with the entanglement between the spins of the chain. We discuss the entanglement properties, quantum chaos, quantum disorder and semi-classical similarity of our quantum chimera system. The quantum chimera concept is novel and induces new perspectives concerning the entanglement of multipartite systems. - Highlights: • We propose a spin chain model with long range couplings having purely quantum states similar to the classical chimera states. • The quantum chimera states are characterized by the coexistence of strongly entangled and non-entangled spins in the same chain. • The quantum chimera states present some characteristics of quantum chaos.

Quantum chimera states

Energy Technology Data Exchange (ETDEWEB)

Viennot, David, E-mail: david.viennot@utinam.cnrs.fr; Aubourg, Lucile

2016-02-15

We study a theoretical model of closed quasi-hermitian chain of spins which exhibits quantum analogues of chimera states, i.e. long life classical states for which a part of an oscillator chain presents an ordered dynamics whereas another part presents a disordered dynamics. For the quantum analogue, the chimera behaviour deals with the entanglement between the spins of the chain. We discuss the entanglement properties, quantum chaos, quantum disorder and semi-classical similarity of our quantum chimera system. The quantum chimera concept is novel and induces new perspectives concerning the entanglement of multipartite systems. - Highlights: • We propose a spin chain model with long range couplings having purely quantum states similar to the classical chimera states. • The quantum chimera states are characterized by the coexistence of strongly entangled and non-entangled spins in the same chain. • The quantum chimera states present some characteristics of quantum chaos.

HIV-1 Nef binds with human GCC185 protein and regulates mannose 6 phosphate receptor recycling

Energy Technology Data Exchange (ETDEWEB)

Kumar, Manjeet; Kaur, Supinder; Nazir, Aamir; Tripathi, Raj Kamal, E-mail: rajkamalcdri@gmail.com

2016-05-20

HIV-1 Nef modulates cellular function that enhances viral replication in vivo which culminate into AIDS pathogenesis. With no enzymatic activity, Nef regulates cellular function through host protein interaction. Interestingly, trans-cellular introduction of recombinant Nef protein in Caenorhabditis elegans results in AIDS like pathogenesis which might share common pathophysiology because the gene sequence of C. elegans and humans share considerable homology. Therefore employing C. elegans based initial screen complemented with sequence based homology search we identified GCC185 as novel host protein interacting with HIV-1 Nef. The detailed molecular characterization revealed N-terminal EEEE{sub 65} acidic domain of Nef as key region for interaction. GCC185 is a tethering protein that binds with Rab9 transport vesicles. Our results show that Nef-GCC185 interaction disrupts Rab9 interaction resulting in delocalization of CI-MPR (cation independent Mannose 6 phosphate receptor) resulting in elevated secretion of hexosaminidase. In agreement with this, our studies identified novel host GCC185 protein that interacts with Nef EEEE65 acidic domain interfering GCC185-Rab9 vesicle membrane fusion responsible for retrograde vesicular transport of CI-MPR from late endosomes to TGN. In light of existing report suggesting critical role of Nef-GCC185 interaction reveals valuable mechanistic insights affecting specific protein transport pathway in docking of late endosome derived Rab9 bearing transport vesicle at TGN elucidating role of Nef during viral pathogenesis. -- Highlights: •Nef, an accessory protein of HIV-1 interacts with host factor and culminates into AIDS pathogenesis. •Using Caenorhabditis elegans based screen system, novel Nef interacting cellular protein GCC185 was identified. •Molecular characterization of Nef and human protein GCC185 revealed Nef EEEE{sub 65} key region interacted with full length GCC185. •Nef impeded the GCC185-Rab 9 interaction and

PyChimera: use UCSF Chimera modules in any Python 2.7 project.

Science.gov (United States)

Rodríguez-Guerra Pedregal, Jaime; Maréchal, Jean-Didier

2018-05-15

UCSF Chimera is a powerful visualization tool remarkably present in the computational chemistry and structural biology communities. Built on a C++ core wrapped under a Python 2.7 environment, one could expect to easily import UCSF Chimera's arsenal of resources in custom scripts or software projects. Nonetheless, this is not readily possible if the script is not executed within UCSF Chimera due to the isolation of the platform. UCSF ChimeraX, successor to the original Chimera, partially solves the problem but yet major upgrades need to be undergone so that this updated version can offer all UCSF Chimera features. PyChimera has been developed to overcome these limitations and provide access to the UCSF Chimera codebase from any Python 2.7 interpreter, including interactive programming with tools like IPython and Jupyter Notebooks, making it easier to use with additional third-party software. PyChimera is LGPL-licensed and available at https://github.com/insilichem/pychimera. jaime.rodriguezguerra@uab.cat or jeandidier.marechal@uab.cat. Supplementary data are available at Bioinformatics online.

Inhibition of Apoptosis Overcomes Stage-Related Compatibility Barriers to Chimera Formation in Mouse Embryos.

Science.gov (United States)

Masaki, Hideki; Kato-Itoh, Megumi; Takahashi, Yusuke; Umino, Ayumi; Sato, Hideyuki; Ito, Keiichi; Yanagida, Ayaka; Nishimura, Toshinobu; Yamaguchi, Tomoyuki; Hirabayashi, Masumi; Era, Takumi; Loh, Kyle M; Wu, Sean M; Weissman, Irving L; Nakauchi, Hiromitsu

2016-11-03

Cell types more advanced in development than embryonic stem cells, such as EpiSCs, fail to contribute to chimeras when injected into pre-implantation-stage blastocysts, apparently because the injected cells undergo apoptosis. Here we show that transient promotion of cell survival through expression of the anti-apoptotic gene BCL2 enables EpiSCs and Sox17 + endoderm progenitors to integrate into blastocysts and contribute to chimeric embryos. Upon injection into blastocyst, BCL2-expressing EpiSCs contributed to all bodily tissues in chimeric animals while Sox17 + endoderm progenitors specifically contributed in a region-specific fashion to endodermal tissues. In addition, BCL2 expression enabled rat EpiSCs to contribute to mouse embryonic chimeras, thereby forming interspecies chimeras that could survive to adulthood. Our system therefore provides a method to overcome cellular compatibility issues that typically restrict chimera formation. Application of this type of approach could broaden the use of embryonic chimeras, including region-specific chimeras, for basic developmental biology research and regenerative medicine. Copyright © 2016 Elsevier Inc. All rights reserved.

Allogeneic radiation chimeras induced in SPF mice

International Nuclear Information System (INIS)

Sado, Toshihiko; Kamisaku, Hitoko

1977-01-01

During the past two decades much has been learned concerning the immunobiology of bone marrow chimeras induced in experimental animals as well as in man. However, from the basic as well as clinical points of view, there still remain many unsolved questions yet to be resolved. In this presentation, we discussed some of our recent results on the immunobiology of radiation chimeras induced in specific-pathogen-free (SPF) mice. These included the following: (a) contribution of graft versus host reaction (GVHR) as well non- GVHR mediated immunologic mechanism(s) to the expression of immunologic dysfunctions observed in allogeneic and certain semiallogeneic chimeras, (b) existence of immunoregulatory mechanism as a basis for the apparent lack of immunologic reactivity (tolerance) to the host- as well as to the donor-type alloantigens in situ in successful allogeneic bone marrow chimeras, and (c) the effect of microflora of the environment on the stability of such immunoregulatory mechanisms and its possible mechanism of action. (auth.)

Nef Secretion into Extracellular Vesicles or Exosomes Is Conserved across Human and Simian Immunodeficiency Viruses

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Ryan P. McNamara

2018-02-01

Full Text Available Extracellular vesicles (EVs or exosomes have been implicated in the pathophysiology of infections and cancer. The negative regulatory factor (Nef encoded by simian immunodeficiency virus (SIV and human immunodeficiency virus (HIV plays a critical role in the progression to AIDS and impairs endosomal trafficking. Whether HIV-1 Nef can be loaded into EVs has been the subject of controversy, and nothing is known about the connection between SIV Nef and EVs. We find that both SIV and HIV-1 Nef proteins are present in affinity-purified EVs derived from cultured cells, as well as in EVs from SIV-infected macaques. Nef-positive EVs were functional, i.e., capable of membrane fusion and depositing their content into recipient cells. The EVs were able to transfer Nef into recipient cells. This suggests that Nef readily enters the exosome biogenesis pathway, whereas HIV virions are assembled at the plasma membrane. It suggests a novel mechanism by which lentiviruses can influence uninfected and uninfectable, i.e., CD4-negative, cells.

Inducing and destruction of chimeras and chimera-like states by an external harmonic force

Science.gov (United States)

Shepelev, I. A.; Vadivasova, T. E.

2018-03-01

We study the phenomena of chimera destruction and inducing of chimera-like states in an ensemble of nonlocally coupled chaotic Rössler oscillators under an external harmonic force. The localized harmonic influence can lead to both destruction and changing of the spatial topology of chimeras. At the same time this influence can cause the emergence of stable chimera-like states (induced chimeras) for the regime of partial coherent chaos. Induced chimeras are also observed for the global influence. We show the possibility of controlling the chimera-like state topology by varying the parameters of localized external harmonic influence.

HIV-1 Nef control of cell signalling molecules: multiple strategies

Indian Academy of Sciences (India)

HIV-1 has at its disposal numerous proteins encoded by its genome which provide the required arsenal to establish and maintain infection in its host for a considerable number of years. One of the most important and enigmatic of these proteins is Nef. The Nef protein of HIV-1 plays a fundamental role in the virus life cycle.

Immunization of mice with the nef gene from Human Immunodeficiency Virus type 1: Study of immunological memory and long-term toxicology

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Engström Gunnel

2007-07-01

Full Text Available Abstract Background The human immunodeficiency virus type 1 (HIV-1 regulatory protein, Nef, is an attractive vaccine target because it is involved in viral pathogenesis, is expressed early in the viral life cycle and harbors many T and B cell epitopes. Several clinical trials include gene-based vaccines encoding this protein. However, Nef has been shown to transform certain cell types in vitro. Based on these findings we performed a long-term toxicity and immunogenicity study of Nef, encoded either by Modified Vaccinia virus Ankara or by plasmid DNA. BALB/c mice were primed twice with either DNA or MVA encoding Nef and received a homologous or heterologous boost ten months later. In the meantime, the Nef-specific immune responses were monitored and at the time of sacrifice an extensive toxicological evaluation was performed, where presence of tumors and other pathological changes were assessed. Results The toxicological evaluation showed that immunization with MVAnef is safe and does not cause cellular transformation or other toxicity in somatic organs. Both DNAnef and MVAnef immunized animals developed potent Nef-specific cellular responses that declined to undetectable levels over time, and could readily be boosted after almost one year. This is of particular interest since it shows that plasmid DNA vaccine can also be used as a potent late booster of primed immune responses. We observed qualitative differences between the T cell responses induced by the two different vectors: DNA-encoded nef induced long-lasting CD8+ T cell memory responses, whereas MVA-encoded nef induced CD4+ T cell memory responses. In terms of the humoral immune responses, we show that two injections of MVAnef induce significant anti-Nef titers, while repeated injections of DNAnef do not. A single boost with MVAnef could enhance the antibody response following DNAnef prime to the same level as that observed in animals immunized repeatedly with MVAnef. We also demonstrate

IL-12 and GM-CSF in DNA/MVA immunizations against HIV-1 CRF12_BF Nef induced T-cell responses with an enhanced magnitude, breadth and quality.

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Ana María Rodríguez

Full Text Available In Argentina, the HIV epidemic is characterized by the co-circulation of subtype B and BF recombinant viral variants. Nef is an HIV protein highly variable among subtypes, making it a good tool to study the impact of HIV variability in the vaccine design setting. We have previously reported a specific cellular response against NefBF with low cross-reactivity to NefB in mice. The aim of this work was to analyze whether the co-administration of IL-12 and GM-CSF, using DNA and MVA vaccine vectors, could improve the final cellular response induced. Mice received three DNA priming doses of a plasmid that express NefBF plus DNAs expressing IL-12 and/or GM-CSF. Afterwards, all the groups were boosted with a MVAnefBF dose. The highest increase in the magnitude of the NefBF response, compared to that induced in the control was found in the IL-12 group. Importantly, a response with higher breadth was detected in groups which received IL-12 or GM-CSF, evidenced as an increased frequency of recognition of homologous (BF and heterologous (B Nef peptides, as well as a higher number of other Nef peptide pools representing different viral subtypes. However, these improvements were lost when both DNA cytokines were simultaneously administered, as the response was focused against the immunodominant peptide with a detrimental response towards subdominant epitopes. The pattern of cytokines secreted and the specific-T-cell proliferative capacity were improved in IL-12 and IL-12+GM-CSF groups. Importantly IL-12 generated a significant higher T-cell avidity against a B heterologous peptide.This study indicates that the incorporation of DNA expressing IL-12 in DNA/MVA schemes produced the best results in terms of improvements of T-cell-response key properties such as breadth, cross-reactivity and quality (avidity and pattern of cytokines secreted. These relevant results contribute to the design of strategies aimed to induce T-cell responses against HIV antigens with

In vivo mutational analysis of the N-terminal region of HIV-1 Nef reveals critical motifs for the development of an AIDS-like disease in CD4C/HIV transgenic mice

International Nuclear Information System (INIS)

Hanna, Zaher; Priceputu, Elena; Kay, Denis G.; Poudrier, Johanne; Chrobak, Pavel; Jolicoeur, Paul

2004-01-01

HIV-1 Nef is a critical determinant of pathogenicity in humans and transgenic (Tg) mice. To gain a better understanding of the molecular mechanisms by which Nef induces an AIDS-like disease in Tg mice, a mutational analysis of the N-terminal domain, involved in anchoring Nef to the plasma membrane, was carried out. The pathogenic effects of these Nef mutant alleles were evaluated in Tg mice by FACS analysis and by histopathological assessment. Mutation of the myristoylation site (G2A) completely abrogated the development of the AIDS-like organ disease in Tg mice, although partial downregulation of the CD4 cell surface protein and depletion of peripheral CD4 + T-cells, but not of CD4 + CD8 + thymocytes, still occurred. Despite that, the peripheral CD4 + T cells expressing Nef G2A show normal spontaneous proliferation in vivo or after stimulation in vitro, including in an allogenic mixed leukocyte reaction (MLR). Three other internal deletion mutants of Nef, spanning amino acids 8-17 (Nef Δ8-17 ), 25-35 (Nef Δ25-35 ), and 57-66 (Nef Δ57-66 ), were also studied. Nef Δ8-17 retained full pathogenic potential, although Nef Δ25-35 and Nef Δ57-66 Tg mice were free of organ disease. However, Nef Δ25-35 Tg mice exhibited disorganization of thymic architecture and a partial depletion of peripheral CD4 + T cells. These data indicate that myristoylation and other regions at the N-terminus of Nef (aa 25-35 and 57-66) are involved in mediating severe T-cell phenotypes and organ disease, although residues 8-17 are dispensable for these Nef functions. In addition, these results indicate that at least some of the CD4 + T-cell phenotypes can develop independently of the other AIDS-like organ phenotypes. This apparent segregation of different Nef-mediated phenotypes suggests distinct mechanisms of Nef action in different populations of target cells, and may be relevant to human AIDS

The mathematics behind chimera states

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Omel’chenko, O. E.

2018-05-01

Chimera states are self-organized spatiotemporal patterns of coexisting coherence and incoherence. We give an overview of the main mathematical methods used in studies of chimera states, focusing on chimera states in spatially extended coupled oscillator systems. We discuss the continuum limit approach to these states, Ott-Antonsen manifold reduction, finite size chimera states, control of chimera states and the influence of system design on the type of chimera state that is observed.

Nef decreases HIV-1 sensitivity to neutralizing antibodies that target the membrane-proximal external region of TMgp41.

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Rachel P J Lai

2011-12-01

Full Text Available Primate lentivirus nef is required for sustained virus replication in vivo and accelerated progression to AIDS. While exploring the mechanism by which Nef increases the infectivity of cell-free virions, we investigated a functional link between Nef and Env. Since we failed to detect an effect of Nef on the quantity of virion-associated Env, we searched for qualitative changes by examining whether Nef alters HIV-1 sensitivity to agents that target distinct features of Env. Nef conferred as much as 50-fold resistance to 2F5 and 4E10, two potent neutralizing monoclonal antibodies (nAbs that target the membrane proximal external region (MPER of TMgp41. In contrast, Nef had no effect on HIV-1 neutralization by MPER-specific nAb Z13e1, by the peptide inhibitor T20, nor by a panel of nAbs and other reagents targeting gp120. Resistance to neutralization by 2F5 and 4E10 was observed with Nef from a diverse range of HIV-1 and SIV isolates, as well as with HIV-1 virions bearing Env from CCR5- and CXCR4-tropic viruses, clade B and C viruses, or primary isolates. Functional analysis of a panel of Nef mutants revealed that this activity requires Nef myristoylation but that it is genetically separable from other Nef functions such as the ability to enhance virus infectivity and to downregulate CD4. Glycosylated-Gag from MoMLV substituted for Nef in conferring resistance to 2F5 and 4E10, indicating that this activity is conserved in a retrovirus that does not encode Nef. Given the reported membrane-dependence of MPER-recognition by 2F5 and 4E10, in contrast to the membrane-independence of Z13e1, the data here is consistent with a model in which Nef alters MPER recognition in the context of the virion membrane. Indeed, Nef and Glycosylated-Gag decreased the efficiency of virion capture by 2F5 and 4E10, but not by other nAbs. These studies demonstrate that Nef protects lentiviruses from one of the most broadly-acting classes of neutralizing antibodies. This newly

Evolution of nef variants in gut associated lymphoid tissue of rhesus macaques during primary simian immunodeficiency virus infection

International Nuclear Information System (INIS)

Ndolo, Thomas; Syvanen, Michael; Ellison, Thomas; Dandekar, Satya

2005-01-01

We utilized the simian immunodeficiency virus model of AIDS to examine evolution of nef gene in gut-associated lymphoid tissue (GALT) during primary and early asymptomatic stages of infection. Macaques were infected with a cloned virus, SIVmac239/nef-stop harboring a premature stop codon in the nef gene. Restoration of the nef open reading frame occurred in GALT early at 3 days post-infection. Analysis of nef sequences by phylogenetic tools showed that evolution of nef was neutral thereafter, as evidenced by the ratio of synonymous to nonsynonymous substitutions, a star pattern in unrooted trees and distribution of amino acid replacements fitting a simple Poisson process. Two regions encoding for a nuclear localization signal and a CTL epitope were conserved. Thus, GALT was a site for strong positive selection of functional nef during initial stages of infection. However, evolution of the nef gene thereafter was neutral during early asymptomatic stage of infection

Chimera states in bursting neurons

OpenAIRE

Bera, Bidesh K.; Ghosh, Dibakar; Lakshmanan, M.

2015-01-01

We study the existence of chimera states in pulse-coupled networks of bursting Hindmarsh-Rose neurons with nonlocal, global and local (nearest neighbor) couplings. Through a linear stability analysis, we discuss the behavior of stability function in the incoherent (i.e. disorder), coherent, chimera and multi-chimera states. Surprisingly, we find that chimera and multi-chimera states occur even using local nearest neighbor interaction in a network of identical bursting neurons alone. This is i...

Characterization of Gag and Nef-specific ELISpot-based CTL responses in HIV-1 infected Indian individuals.

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Mendiratta, Sanjay; Vajpayee, Madhu; Malhotra, Uma; Kaushik, Shweta; Dar, Lalit; Mojumdar, Kamalika; Chauhan, Neeraj Kumar; Sreenivas, Vishnubhatla

2009-02-01

Cytotoxic T lymphocyte (CTL) responses to Gag have been most frequently linked to control of viremia whereas CTL responses to Nef have direct relationship with viral load. IFN-gamma ELISpot assay was used to screen CTL responses at single peptide level directed at HIV-1 subtype C Gag and Nef proteins in 30 antiretroviral therapy naive HIV-1 infected Indian individuals. PBMCs from 73.3% and 90% of the study population showed response to Gag and Nef antigens, respectively. The magnitude of Gag-specific CTL responses was inversely correlated with plasma viral load (r = -0.45, P = 0.001), whereas magnitude of Nef-specific responses was directly correlated (r = 0.115). Thirteen immunodominant regions (6 in Gag, 7 in Nef) were identified in the current study. The identification of Gag and Nef-specific responses across HIV-1 infected Indian population and targeting epitopes from multiple immunodominant regions may provide useful insight into the designing of new immunotherapy and vaccines.

Human Immunodeficiency Virus Type 1 Nef protein modulates the lipid composition of virions and host cell membrane microdomains

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Geyer Matthias

2007-10-01

Full Text Available Abstract Background The Nef protein of Human Immunodeficiency Viruses optimizes viral spread in the infected host by manipulating cellular transport and signal transduction machineries. Nef also boosts the infectivity of HIV particles by an unknown mechanism. Recent studies suggested a correlation between the association of Nef with lipid raft microdomains and its positive effects on virion infectivity. Furthermore, the lipidome analysis of HIV-1 particles revealed a marked enrichment of classical raft lipids and thus identified HIV-1 virions as an example for naturally occurring membrane microdomains. Since Nef modulates the protein composition and function of membrane microdomains we tested here if Nef also has the propensity to alter microdomain lipid composition. Results Quantitative mass spectrometric lipidome analysis of highly purified HIV-1 particles revealed that the presence of Nef during virus production from T lymphocytes enforced their raft character via a significant reduction of polyunsaturated phosphatidylcholine species and a specific enrichment of sphingomyelin. In contrast, Nef did not significantly affect virion levels of phosphoglycerolipids or cholesterol. The observed alterations in virion lipid composition were insufficient to mediate Nef's effect on particle infectivity and Nef augmented virion infectivity independently of whether virus entry was targeted to or excluded from membrane microdomains. However, altered lipid compositions similar to those observed in virions were also detected in detergent-resistant membrane preparations of virus producing cells. Conclusion Nef alters not only the proteome but also the lipid composition of host cell microdomains. This novel activity represents a previously unrecognized mechanism by which Nef could manipulate HIV-1 target cells to facilitate virus propagation in vivo.

Simian Immunodeficiency Virus and Human Immunodeficiency Virus Type 1 Nef Proteins Show Distinct Patterns and Mechanisms of Src Kinase Activation

Science.gov (United States)

Greenway, Alison L.; Dutartre, Hélène; Allen, Kelly; McPhee, Dale A.; Olive, Daniel; Collette, Yves

1999-01-01

The nef gene from human and simian immunodeficiency viruses (HIV and SIV) regulates cell function and viral replication, possibly through binding of the nef product to cellular proteins, including Src family tyrosine kinases. We show here that the Nef protein encoded by SIVmac239 interacts with and also activates the human Src kinases Lck and Hck. This is in direct contrast to the inhibitory effect of HIV type 1 (HIV-1) Nef on Lck catalytic activity. Unexpectedly, however, the interaction of SIV Nef with human Lck or Hck is not mediated via its consensus proline motif, which is known to mediate HIV-1 Nef binding to Src homology 3 (SH3) domains, and various experimental analyses failed to show significant interaction of SIV Nef with the SH3 domain of either kinase. Instead, SIV Nef can bind Lck and Hck SH2 domains, and its N-terminal 50 amino acid residues are sufficient for Src kinase binding and activation. Our results provide evidence for multiple mechanisms by which Nef binds to and regulates Src kinases. PMID:10364375

Brain transcriptome-wide screen for HIV-1 Nef protein interaction partners reveals various membrane-associated proteins.

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Ellen C Kammula

Full Text Available HIV-1 Nef protein contributes essentially to the pathology of AIDS by a variety of protein-protein-interactions within the host cell. The versatile functionality of Nef is partially attributed to different conformational states and posttranslational modifications, such as myristoylation. Up to now, many interaction partners of Nef have been identified using classical yeast two-hybrid screens. Such screens rely on transcriptional activation of reporter genes in the nucleus to detect interactions. Thus, the identification of Nef interaction partners that are integral membrane proteins, membrane-associated proteins or other proteins that do not translocate into the nucleus is hampered. In the present study, a split-ubiquitin based yeast two-hybrid screen was used to identify novel membrane-localized interaction partners of Nef. More than 80% of the hereby identified interaction partners of Nef are transmembrane proteins. The identified hits are GPM6B, GPM6A, BAP31, TSPAN7, CYB5B, CD320/TCblR, VSIG4, PMEPA1, OCIAD1, ITGB1, CHN1, PH4, CLDN10, HSPA9, APR-3, PEBP1 and B3GNT, which are involved in diverse cellular processes like signaling, apoptosis, neurogenesis, cell adhesion and protein trafficking or quality control. For a subfraction of the hereby identified proteins we present data supporting their direct interaction with HIV-1 Nef. We discuss the results with respect to many phenotypes observed in HIV infected cells and patients. The identified Nef interaction partners may help to further elucidate the molecular basis of HIV-related diseases.

Recurrence quantification analysis of chimera states

International Nuclear Information System (INIS)

Santos, M.S.; Szezech, J.D.; Batista, A.M.; Caldas, I.L.; Viana, R.L.; Lopes, S.R.

2015-01-01

Chimera states, characterised by coexistence of coherence and incoherence in coupled dynamical systems, have been found in various physical systems, such as mechanical oscillator networks and Josephson-junction arrays. We used recurrence plots to provide graphical representations of recurrent patterns and identify chimera states. Moreover, we show that recurrence plots can be used as a diagnostic of chimera states and also to identify the chimera collapse. - Highlights: • Chimera states have been found in various physical systems. • Recurrence plots is a graphical method useful to locate recurring patterns. • We used recurrence plots to identify the chimera states. • We show also the recurrence plots can identify the chimera collapse

Recurrence quantification analysis of chimera states

Energy Technology Data Exchange (ETDEWEB)

Santos, M.S. [Pós-Graduação em Ciências/Física, Universidade Estadual de Ponta Grossa, 84030-900, Ponta Grossa, PR (Brazil); Szezech, J.D., E-mail: jdanilo@gmail.com [Departamento de Matemática e Estatística, Universidade Estadual de Ponta Grossa, 84030-900, Ponta Grossa, PR (Brazil); Batista, A.M., E-mail: antoniomarcosbatista@gmail.com [Departamento de Matemática e Estatística, Universidade Estadual de Ponta Grossa, 84030-900, Ponta Grossa, PR (Brazil); Caldas, I.L. [Instituto de Física, Universidade de São Paulo, 05315-970, São Paulo, SP (Brazil); Viana, R.L.; Lopes, S.R. [Departamento de Física, Universidade Federal do Paraná, 81531-990, Curitiba, PR (Brazil)

2015-10-02

Chimera states, characterised by coexistence of coherence and incoherence in coupled dynamical systems, have been found in various physical systems, such as mechanical oscillator networks and Josephson-junction arrays. We used recurrence plots to provide graphical representations of recurrent patterns and identify chimera states. Moreover, we show that recurrence plots can be used as a diagnostic of chimera states and also to identify the chimera collapse. - Highlights: • Chimera states have been found in various physical systems. • Recurrence plots is a graphical method useful to locate recurring patterns. • We used recurrence plots to identify the chimera states. • We show also the recurrence plots can identify the chimera collapse.

Dynamic range of Nef-mediated evasion of HLA class II-restricted immune responses in early HIV-1 infection.

Science.gov (United States)

Mahiti, Macdonald; Brumme, Zabrina L; Jessen, Heiko; Brockman, Mark A; Ueno, Takamasa

2015-07-31

HLA class II-restricted CD4(+) T lymphocytes play an important role in controlling HIV-1 replication, especially in the acute/early infection stage. But, HIV-1 Nef counteracts this immune response by down-regulating HLA-DR and up-regulating the invariant chain associated with immature HLA-II (Ii). Although functional heterogeneity of various Nef activities, including down-regulation of HLA class I (HLA-I), is well documented, our understanding of Nef-mediated evasion of HLA-II-restricted immune responses during acute/early infection remains limited. Here, we examined the ability of Nef clones from 47 subjects with acute/early progressive infection and 46 subjects with chronic progressive infection to up-regulate Ii and down-regulate HLA-DR and HLA-I from the surface of HIV-infected cells. HLA-I down-regulation function was preserved among acute/early Nef clones, whereas both HLA-DR down-regulation and Ii up-regulation functions displayed relatively broad dynamic ranges. Nef's ability to down-regulate HLA-DR and up-regulate Ii correlated positively at this stage, suggesting they are functionally linked in vivo. Acute/early Nef clones also exhibited higher HLA-DR down-regulation and lower Ii up-regulation functions compared to chronic Nef clones. Taken together, our results support enhanced Nef-mediated HLA class II immune evasion activities in acute/early compared to chronic infection, highlighting the potential importance of these functions following transmission. Copyright © 2015 Elsevier Inc. All rights reserved.

Evolution of the HIV-1 nef gene in HLA-B*57 Positive Elite Suppressors

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Siliciano Robert F

2010-11-01

Full Text Available Abstract Elite controllers or suppressors (ES are HIV-1 infected patients who maintain viral loads of gag and nef in HLA-B*57 positive ES. We previously showed evolution in the gag gene of ES which surprisingly was mostly due to synonymous mutations rather than non-synonymous mutation in targeted CTL epitopes. This finding could be the result of structural constraints on Gag, and we therefore examined the less conserved nef gene. We found slow evolution of nef in plasma virus in some ES. This evolution is mostly due to synonymous mutations and occurs at a rate similar to that seen in the gag gene in the same patients. The results provide further evidence of ongoing viral replication in ES and suggest that the nef and gag genes in these patients respond similarly to selective pressure from the host.

Gargoyles, Grotesques, & Chimeras

Science.gov (United States)

Wilbert, Nancy Corrigan

2010-01-01

Gargoyles, grotesques, and chimeras are scary, mythical (and sometimes humorous) creatures that have functional, decorative, and spiritual significance in medieval architecture. In this article, the author describes how her ceramics students created contemporary versions of gargoyles, chimeras, and grotesque faces. (Contains 1 online resource.)

Structural defects and variations in the HIV-1 nef gene from rapid, slow and non-progressor children.

Science.gov (United States)

Casartelli, Nicoletta; Di Matteo, Gigliola; Argentini, Claudio; Cancrini, Caterina; Bernardi, Stefania; Castelli, Guido; Scarlatti, Gabriella; Plebani, Anna; Rossi, Paolo; Doria, Margherita

2003-06-13

Evaluation of sequence evolution as well as structural defects and mutations of the human immunodeficiency virus-type 1 (HIV-1) nef gene in relation to disease progression in infected children. We examined a large number of nef alleles sequentially derived from perinatally HIV-1-infected children with different rates of disease progression: six non-progressors (NPs), four rapid progressors (RPs), and three slow progressors (SPs). Nef alleles (182 total) were isolated from patients' peripheral blood mononuclear cells (PBMCs), sequenced and analysed for their evolutionary pattern, frequency of mutations and occurrence of amino acid variations associated with different stages of disease. The evolution rate of the nef gene apparently correlated with CD4+ decline in all progression groups. Evidence for rapid viral turnover and positive selection for changes were found only in two SPs and two RPs respectively. In NPs, a higher proportion of disrupted sequences and mutations at various functional motifs were observed. Furthermore, NP-derived Nef proteins were often changed at residues localized in the folded core domain at cytotoxic T lymphocytes (CTL) epitopes (E(105), K(106), E(110), Y(132), K(164), and R(200)), while other residues outside the core domain are more often changed in RPs (A(43)) and SPs (N(173) and Y(214)). Our results suggest a link between nef gene functions and the progression rate in HIV-1-infected children. Moreover, non-progressor-associated variations in the core domain of Nef, together with the genetic analysis, suggest that nef gene evolution is shaped by an effective immune system in these patients.

Interordinal chimera formation between medaka and zebrafish for analyzing stem cell differentiation.

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Hong, Ni; Chen, Songlin; Ge, Ruowen; Song, Jianxing; Yi, Meisheng; Hong, Yunhan

2012-08-10

Chimera formation is a standard test for pluripotency of stem cells in vivo. Interspecific chimera formation between distantly related organisms offers also an attractive approach for propagating endangered species. Parameters influencing interspecies chimera formation have remained poorly elucidated. Here, we report interordinal chimera formation between medaka and zebrafish, which separated ∼320 million years ago and exhibit a more than 2-fold difference in developmental speed. We show that, on transplantation into zebrafish blastulae, both noncultivated blastomeres and long-term cultivated embryonic stem (ES) cells of medaka adopted the zebrafish developmental program and differentiated into physiologically functional cell types including pigment cells, blood cells, and cardiomyocytes. We also show that medaka ES cells express differentiation gene markers during chimeric embryogenesis. Therefore, the evolutionary distance and different embryogenesis speeds do not produce donor-host incompatibility to compromise chimera formation between medaka and zebrafish, and molecular markers are valuable for analyzing lineage commitment and cell differentiation in interspecific chimeric embryos.

HIV-1 Infection of T Cells and Macrophages Are Differentially Modulated by Virion-Associated Hck: A Nef-Dependent Phenomenon

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Gilda Tachedjian

2013-09-01

Full Text Available The proline repeat motif (PxxP of Nef is required for interaction with the SH3 domains of macrophage-specific Src kinase Hck. However, the implication of this interaction for viral replication and infectivity in macrophages and T lymphocytes remains unclear. Experiments in HIV-1 infected macrophages confirmed the presence of a Nef:Hck complex which was dependent on the Nef proline repeat motif. The proline repeat motif of Nef also enhanced both HIV-1 infection and replication in macrophages, and was required for incorporation of Hck into viral particles. Unexpectedly, wild-type Hck inhibited infection of macrophages, but Hck was shown to enhance infection of primary T lymphocytes. These results indicate that the interaction between Nef and Hck is important for Nef-dependent modulation of viral infectivity. Hck-dependent enhancement of HIV-1 infection of T cells suggests that Nef-Hck interaction may contribute to the spread of HIV-1 infection from macrophages to T cells by modulating events in the producer cell, virion and target cell.

HIV-1 Nef hijacks clathrin coats by stabilizing AP-1:Arf1 polygons.

Science.gov (United States)

Shen, Qing-Tao; Ren, Xuefeng; Zhang, Rui; Lee, Il-Hyung; Hurley, James H

2015-10-23

The lentiviruses HIV and simian immunodeficiency virus (SIV) subvert intracellular membrane traffic as part of their replication cycle. The lentiviral Nef protein helps viruses evade innate and adaptive immune defenses by hijacking the adaptor protein 1 (AP-1) and AP-2 clathrin adaptors. We found that HIV-1 Nef and the guanosine triphosphatase Arf1 induced trimerization and activation of AP-1. Here we report the cryo-electron microscopy structures of the Nef- and Arf1-bound AP-1 trimer in the active and inactive states. A central nucleus of three Arf1 molecules organizes the trimers. We combined the open trimer with a known dimer structure and thus predicted a hexagonal assembly with inner and outer faces that bind the membranes and clathrin, respectively. Hexagons were directly visualized and the model validated by reconstituting clathrin cage assembly. Arf1 and Nef thus play interconnected roles in allosteric activation, cargo recruitment, and coat assembly, revealing an unexpectedly intricate organization of the inner AP-1 layer of the clathrin coat. Copyright © 2015, American Association for the Advancement of Science.

Identification of a highly conserved valine-glycine-phenylalanine amino acid triplet required for HIV-1 Nef function

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Meuwissen Pieter J

2012-04-01

Full Text Available Abstract Background The Nef protein of HIV facilitates virus replication and disease progression in infected patients. This role as pathogenesis factor depends on several genetically separable Nef functions that are mediated by interactions of highly conserved protein-protein interaction motifs with different host cell proteins. By studying the functionality of a series of nef alleles from clinical isolates, we identified a dysfunctional HIV group O Nef in which a highly conserved valine-glycine-phenylalanine (VGF region, which links a preceding acidic cluster with the following proline-rich motif into an amphipathic surface was deleted. In this study, we aimed to study the functional importance of this VGF region. Results The dysfunctional HIV group O8 nef allele was restored to the consensus sequence, and mutants of canonical (NL4.3, NA-7, SF2 and non-canonical (B2 and C1422 HIV-1 group M nef alleles were generated in which the amino acids of the VGF region were changed into alanines (VGF→AAA and tested for their capacity to interfere with surface receptor trafficking, signal transduction and enhancement of viral replication and infectivity. We found the VGF motif, and each individual amino acid of this motif, to be critical for downregulation of MHC-I and CXCR4. Moreover, Nef’s association with the cellular p21-activated kinase 2 (PAK2, the resulting deregulation of cofilin and inhibition of host cell actin remodeling, and targeting of Lck kinase to the trans-golgi-network (TGN were affected as well. Of particular interest, VGF integrity was essential for Nef-mediated enhancement of HIV virion infectivity and HIV replication in peripheral blood lymphocytes. For targeting of Lck kinase to the TGN and viral infectivity, especially the phenylalanine of the triplet was essential. At the molecular level, the VGF motif was required for the physical interaction of the adjacent proline-rich motif with Hck. Conclusion Based on these findings, we

Dynamic features of apo and bound HIV-Nef protein reveal the anti-HIV dimerization inhibition mechanism.

Science.gov (United States)

Moonsamy, Suri; Bhakat, Soumendranath; Soliman, Mahmoud E S

2015-01-01

The first account on the dynamic features of Nef or negative factor, a small myristoylated protein located in the cytoplasm believes to increase HIV-1 viral titer level, is reported herein. Due to its major role in HIV-1 pathogenicity, Nef protein is considered an emerging target in anti-HIV drug design and discovery process. In this study, comparative long-range all-atom molecular dynamics simulations were employed for apo and bound protein to unveil molecular mechanism of HIV-Nef dimerization and inhibition. Results clearly revealed that B9, a newly discovered Nef inhibitor, binds at the dimeric interface of Nef protein and caused significant separation between orthogonally opposed residues, namely Asp108, Leu112 and Gln104. Large differences in magnitudes were observed in the radius of gyration (∼1.5 Å), per-residue fluctuation (∼2 Å), C-alpha deviations (∼2 Å) which confirm a comparatively more flexible nature of apo conformation due to rapid dimeric association. Compared to the bound conformer, a more globally correlated motion in case of apo structure of HIV-Nef confirms the process of dimeric association. This clearly highlights the process of inhibition as a result of ligand binding. The difference in principal component analysis (PCA) scatter plot and per-residue mobility plot across first two normal modes further justifies the same findings. The in-depth dynamic analyses of Nef protein presented in this report would serve crucial in understanding its function and inhibition mechanisms. Information on inhibitor binding mode would also assist in designing of potential inhibitors against this important HIV target.

Multiple scroll wave chimera states

Science.gov (United States)

Maistrenko, Volodymyr; Sudakov, Oleksandr; Osiv, Oleksiy; Maistrenko, Yuri

2017-06-01

We report the appearance of three-dimensional (3D) multiheaded chimera states that display cascades of self-organized spatiotemporal patterns of coexisting coherence and incoherence. We demonstrate that the number of incoherent chimera domains can grow additively under appropriate variations of the system parameters generating thereby head-adding cascades of the scroll wave chimeras. The phenomenon is derived for the Kuramoto model of N 3 identical phase oscillators placed in the unit 3D cube with periodic boundary conditions, parameters being the coupling radius r and phase lag α. To obtain the multiheaded chimeras, we perform the so-called `cloning procedure' as follows: choose a sample single-headed 3D chimera state, make appropriate scale transformation, and put some number of copies of them into the unit cube. After that, start numerical simulations with slightly perturbed initial conditions and continue them for a sufficiently long time to confirm or reject the state existence and stability. In this way it is found, that multiple scroll wave chimeras including those with incoherent rolls, Hopf links and trefoil knots admit this sort of multiheaded regeneration. On the other hand, multiple 3D chimeras without spiral rotations, like coherent and incoherent balls, tubes, crosses, and layers appear to be unstable and are destroyed rather fast even for arbitrarily small initial perturbations.

Nef does not contribute to replication differences between R5 pre-AIDS and AIDS HIV-1 clones from patient ACH142

Directory of Open Access Journals (Sweden)

Rekosh David

2008-05-01

Full Text Available Abstract AIDS-associated, CCR5-tropic (R5 HIV-1 clones, isolated from a patient that never developed CXCR4-tropic HIV-1, replicate to a greater extent and cause greater cytopathic effects than R5 HIV-1 clones isolated before the onset of AIDS. Previously, we showed that HIV-1 Env substantially contributed to the enhanced replication of an AIDS clone. In order to determine if Nef makes a similar contribution, we cloned and phenotypically analyzed nef genes from a series of patient ACH142 derived R5 HIV-1 clones. The AIDS-associated Nef contains a series of residues found in Nef proteins from progressors 1. In contrast to other reports 123, this AIDS-associated Nef downmodulated MHC-I to a greater extent and CD4 less than pre-AIDS Nef proteins. Additionally, all Nef proteins enhanced infectivity similarly in a single round of replication. Combined with our previous study, these data show that evolution of the HIV-1 env gene, but not the nef gene, within patient ACH142 significantly contributed to the enhanced replication and cytopathic effects of the AIDS-associated R5 HIV-1 clone.

Immune tolerance in radiation chimeras

International Nuclear Information System (INIS)

Awaya, Kazuhiko; Kuniki, Hiromichi; Neki, Miyuki

1978-01-01

Establishment of immune tolerance in radiation chimeras and the mechanism of maintaining it were discussed from certain points. Semiallogeneic radiation chimeras are mostly of long-living, and the hematopoietic organ of this individual consists mainly of the cells derived from the marrow donor, i. e., F 1 -type cells. F 1 -type lymphocytes can distinguish parental strain cells from themselves. In these chimeras, a F 1 -skin graft maintains to be fresh as long as the host is alive, showing immune tolerance effective through its life. In establishment and maintenance of this immune tolerance, the suppressing mechanism of host-type or F 1 -type seems to be involved. The allogeneic radiation chimera has very poor long-survival rate compared with that of the semiallogeneic radiation chimera. To raise this survival rate, efforts are now being made from the immunological point of view. (Ueda, J.)

Lentiviral Nef Proteins Utilize PAK2-Mediated Deregulation of Cofilin as a General Strategy To Interfere with Actin Remodeling▿ †

Science.gov (United States)

Stolp, Bettina; Abraham, Libin; Rudolph, Jochen M.; Fackler, Oliver T.

2010-01-01

Nef is an accessory protein and pathogenicity factor of human immunodeficiency virus (HIV) and simian immunodeficiency virus (SIV) which elevates virus replication in vivo. We recently described for HIV type 1SF2 (HIV-1SF2) the potent interference of Nef with T-lymphocyte chemotaxis via its association with the cellular kinase PAK2. Mechanistic analysis revealed that this interaction results in deregulation of the actin-severing factor cofilin and thus blocks the chemokine-mediated actin remodeling required for cell motility. However, the efficiency of PAK2 association is highly variable among Nef proteins from different lentiviruses, prompting us to evaluate the conservation of this actin-remodeling/cofilin-deregulating mechanism. Based on the analysis of a total of 17 HIV-1, HIV-2, and SIV Nef proteins, we report here that inhibition of chemokine-induced actin remodeling as well as inactivation of cofilin are strongly conserved activities of lentiviral Nef proteins. Of note, even for Nef variants that display only marginal PAK2 association in vitro, these activities require the integrity of a PAK2 recruitment motif and the presence of endogenous PAK2. Thus, reduced in vitro affinity to PAK2 does not indicate limited functionality of Nef-PAK2 complexes in intact HIV-1 host cells. These results establish hijacking of PAK2 for deregulation of cofilin and inhibition of triggered actin remodeling as a highly conserved function of lentiviral Nef proteins, supporting the notion that PAK2 association may be critical for Nef's activity in vivo. PMID:20147394

Deficiency in early development of the thymus-dependent cells in irradiation chimeras attributable to recipient's environment

International Nuclear Information System (INIS)

Iwabuchi, C.; Iwabuchi, K.; Kobayashi, S.; Ogasawara, K.; Negishi, I.; Wang, B.Y.; Wambua, P.P.; Arase, H.; Fukushi, N.; Itoh, Y.

1991-01-01

Bone marrow chimeras were prepared using reciprocal combinations of AKR and C3H mice. When C3H mice were recipients, the number of thymocytes recoverable from such chimeras (C3H recipient chimeras) was small as compared with that from chimeras for which AKR mice were used as recipients (AKR recipient chimeras) regardless of donor strain. The thymocytes from C3H recipient chimeras showed a profound deficiency in generating proliferative responses to stimulation by anti-CD3 mAb (2C11) or anti-TCR (alpha, beta) mAb (H57-597), even though the expression of CD3 and TCR molecules fell within the same range as that in AKR recipient chimeras. Furthermore, after stimulation with immobilized 2C11, the proportion of IL-2R+ cells in the thymocytes from C3H recipient chimeras was much less than that in AKR recipient chimeras. However, no significant difference in proliferative responses to 2C11 plus PMA, in influx of Ca2+ after stimulation with 2C11 or IL-2 production in response to 2C11 plus PMA or PMA plus A23187 was demonstrated between C3H and AKR recipient chimeras. These findings suggest that the thymocytes from C3H recipient chimeras have a deficiency in the signal transduction system as compared with chimeras for which AKR mice are the recipients. The thymic stromal component involved in this difference in the C3H recipient chimeras is discussed

A robust and scalable TCR-based reporter cell assay to measure HIV-1 Nef-mediated T cell immune evasion.

Science.gov (United States)

Anmole, Gursev; Kuang, Xiaomei T; Toyoda, Mako; Martin, Eric; Shahid, Aniqa; Le, Anh Q; Markle, Tristan; Baraki, Bemuluyigza; Jones, R Brad; Ostrowski, Mario A; Ueno, Takamasa; Brumme, Zabrina L; Brockman, Mark A

2015-11-01

HIV-1 evades cytotoxic T cell responses through Nef-mediated downregulation of HLA class I molecules from the infected cell surface. Methods to quantify the impact of Nef on T cell recognition typically employ patient-derived T cell clones; however, these assays are limited by the cost and effort required to isolate and maintain primary cell lines. The variable activity of different T cell clones and the limited number of cells generated by re-stimulation can also hinder assay reproducibility and scalability. Here, we describe a heterologous T cell receptor reporter assay and use it to study immune evasion by Nef. Induction of NFAT-driven luciferase following co-culture with peptide-pulsed or virus-infected target cells serves as a rapid, quantitative and antigen-specific measure of T cell recognition of its cognate peptide/HLA complex. We demonstrate that Nef-mediated downregulation of HLA on target cells correlates inversely with T cell receptor-dependent luminescent signal generated by effector cells. This method provides a robust, flexible and scalable platform that is suitable for studies to measure Nef function in the context of different viral peptide/HLA antigens, to assess the function of patient-derived Nef alleles, or to screen small molecule libraries to identify novel Nef inhibitors. Copyright © 2015 Elsevier B.V. All rights reserved.

Periclinal chimera technique: new plant breeding approach.

Science.gov (United States)

Gakpetor, P M; Mohammed, H; Moreti, D; Nassar, N M A

2017-09-21

Plant interspecific periclinal chimeras are a mosaic formed by tissues from two species. They are manipulated here as an efficient plant breeding tool for cassava root yields. In this study, plants synthesized from two chimeras, designated as chimera 2 and chimera 4, were characterized morphologically and cytologically to unravel the origin of their tissue layers (L2 and L3). Root yield of the two chimeras was also evaluated. Chimera 2 that was developed from graft union between Manihot fortalezensis (F) as scion and M. esculenta (E) as rootstock and the same in chimera 4 was developed from grafting triploid cassava cultivar (2n = 54) (C) as scion and M. pohlii (P) (2n = 36) as rootstock. A new method of inducing interspecific chimeras without using hormones was also tested in this study. Five combinations between four cassava cultivars on one side and M. fortalezensis and an interspecific hybrid (M. glaziovii x M. esculenta) on the other side were experimented to determine compatibility between the parents. Wild species always gave L2 and L3, independent of being used as rootstock or scion. L3 is responsible for producing pericycle. Thus, its performance was different in each chimera due to specific epigenetic interaction. Of 48 grafts, it was obtained one chimera giving a percentage of 2.1% that is little lower than using hormones but much efficient to use. Chimera induction efficiency in this investigation was the same when using hormones. Thus, our new, less labor, and more cost-effective technique is as much efficient as hormones and is much potential to employ as an effective plant breeding method boosting cassava root yield.

Enstore with Chimera namespace provider

International Nuclear Information System (INIS)

Litvintsev, Dmitry; Moibenko, Alexander; Oleynik, Gene; Zalokar, Michael

2012-01-01

Enstore is a mass storage system developed by Fermilab that provides distributed access and management of data stored on tapes. It uses a namespace service, PNFS, developed by DESY to provide a filesystem-like view of the stored data. PNFS is a legacy product and is being replaced by a new implementation, called Chimera, which is also developed by DESY. Chimera offers multiple advantages over PNFS in terms of performance and functionality. The Enstore client component, encp, has been modified to work with Chimera, as well as with any other namespace provider. We performed high load end-to-end acceptance test of Enstore with the Chimera namespace. This paper describes the modifications to Enstore, the test procedure and the results of the acceptance testing.

Chimera states in mechanical oscillator networks

DEFF Research Database (Denmark)

Martens, Erik Andreas; Thutupalli, Shashi; Fourrière, Antoine

2013-01-01

of identical oscillators, numerous theoretical studies in recent years have revealed the intriguing possibility of "chimera states," in which the symmetry of the oscillator population is broken into a synchronous part and an asynchronous part. However, a striking lack of empirical evidence raises the question...... of whether chimeras are indeed characteristic of natural systems. This calls for a palpable realization of chimera states without any fine-tuning, from which physical mechanisms underlying their emergence can be uncovered. Here, we devise a simple experiment with mechanical oscillators coupled...... in a hierarchical network to show that chimeras emerge naturally from a competition between two antagonistic synchronization patterns. We identify a wide spectrum of complex states, encompassing and extending the set of previously described chimeras. Our mathematical model shows that the self-organization observed...

Non-identical multiplexing promotes chimera states

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Ghosh, Saptarshi; Zakharova, Anna; Jalan, Sarika

2018-01-01

We present the emergence of chimeras, a state referring to coexistence of partly coherent, partly incoherent dynamics in networks of identical oscillators, in a multiplex network consisting of two non-identical layers which are interconnected. We demonstrate that the parameter range displaying the chimera state in the homogeneous first layer of the multiplex networks can be tuned by changing the link density or connection architecture of the same nodes in the second layer. We focus on the impact of the interconnected second layer on the enlargement or shrinking of the coupling regime for which chimeras are displayed in the homogeneous first layer. We find that a denser homogeneous second layer promotes chimera in a sparse first layer, where chimeras do not occur in isolation. Furthermore, while a dense connection density is required for the second layer if it is homogeneous, this is not true if the second layer is inhomogeneous. We demonstrate that a sparse inhomogeneous second layer which is common in real-world complex systems can promote chimera states in a sparse homogeneous first layer.

Rectal HSV-2 Infection May Increase Rectal SIV Acquisition Even in the Context of SIVΔnef Vaccination.

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Natalia Guerra-Pérez

Full Text Available Prevalent HSV-2 infection increases the risk of HIV acquisition both in men and women even in asymptomatic subjects. Understanding the impact of HSV-2 on the mucosal microenvironment may help to identify determinants of susceptibility to HIV. Vaginal HSV-2 infection increases the frequency of cells highly susceptible to HIV in the vaginal tissue of women and macaques and this correlates with increased susceptibility to vaginal SHIV infection in macaques. However, the effect of rectal HSV-2 infection on HIV acquisition remains understudied. We developed a model of rectal HSV-2 infection in macaques in combination with rectal SIVmac239Δnef (SIVΔnef vaccination and our results suggest that rectal HSV-2 infection may increase the susceptibility of macaques to rectal SIVmac239 wild-type (wt infection even in SIVΔnef-infected animals. Rectal SIVΔnef infection/vaccination protected 7 out of 7 SIVΔnef-infected macaques from SIVmac239wt rectal infection (vs 12 out of 16 SIVΔnef-negative macaques, while 1 out of 3 animals co-infected with SIVΔnef and HSV-2 acquired SIVmac239wt infection. HSV-2/SIVmac239wt co-infected animals had increased concentrations of inflammatory factors in their plasma and rectal fluids and a tendency toward higher acute SIVmac239wt plasma viral load. However, they had higher blood CD4 counts and reduced depletion of CCR5+ CD4+ T cells compared to SIVmac239wt-only infected animals. Thus, rectal HSV-2 infection generates a pro-inflammatory environment that may increase susceptibility to rectal SIV infection and may impact immunological and virological parameters during acute SIV infection. Studies with larger number of animals are needed to confirm these findings.

Mobility-induced persistent chimera states

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Petrungaro, Gabriela; Uriu, Koichiro; Morelli, Luis G.

2017-12-01

We study the dynamics of mobile, locally coupled identical oscillators in the presence of coupling delays. We find different kinds of chimera states in which coherent in-phase and antiphase domains coexist with incoherent domains. These chimera states are dynamic and can persist for long times for intermediate mobility values. We discuss the mechanisms leading to the formation of these chimera states in different mobility regimes. This finding could be relevant for natural and technological systems composed of mobile communicating agents.

Purification and characterization of Yersinia enterocolitica and Yersinia pestis LcrV-cholera toxin A(2)/B chimeras.

Science.gov (United States)

Tinker, Juliette K; Davis, Chadwick T; Arlian, Britni M

2010-11-01

Yersinia pestis is a virulent human pathogen and potential biological weapon. Despite a long history of research on this organism, there is no licensed vaccine to protect against pneumonic forms of Y. pestis disease. In the present study, plasmids were constructed to express cholera toxin A(2)/B chimeric molecules containing the LcrV protective antigen from Yersinia enterocolitica and Y. pestis. These chimeras were expressed and purified to high yields from the supernatant of transformed Escherichia coli. Western and GM(1) ELISA assays were used to characterize the composition, receptor-binding and relative stability of the LcrV-CTA(2)/B chimera in comparison to cholera toxin. In addition, we investigated the ability of the Y. pestis LcrV-CTA(2)/B chimera to bind to and internalize into cultured epithelial cells and macrophages by confocal microscopy. These studies indicate that the uptake and trafficking of the LcrV antigen from the chimera is comparable to the trafficking of native toxin. Together these findings report that stable, receptor-binding, non-toxic LcrV-cholera toxin A(2)/B chimeras can be expressed at high levels in E. coli and purified from the supernatant. In addition, the internalization of antigen in vitro reported here supports the development of these molecules as novel mucosal vaccine candidates. Copyright 2010 Elsevier Inc. All rights reserved.

An MHC-I cytoplasmic domain/HIV-1 Nef fusion protein binds directly to the mu subunit of the AP-1 endosomal coat complex.

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Rajendra Kumar Singh

2009-12-01

Full Text Available The down-regulation of the major histocompatibility complex class I (MHC-I from the surface of infected cells by the Nef proteins of primate immunodeficiency viruses likely contributes to pathogenesis by providing evasion of cell-mediated immunity. HIV-1 Nef-induced down-regulation involves endosomal trafficking and a cooperative interaction between the cytoplasmic domain (CD of MHC-I, Nef, and the clathrin adaptor protein complex-1 (AP-1. The CD of MHC-I contains a key tyrosine within the sequence YSQA that is required for down-regulation by Nef, but this sequence does not conform to the canonical AP-binding tyrosine-based motif Yxxphi, which mediates binding to the medium (micro subunits of AP complexes. We previously proposed that Nef allows the MHC-I CD to bind the mu subunit of AP-1 (micro1 as if it contained a Yxxphimotif.Here, we show that a direct interaction between the MHC-I CD/Nef and micro1 plays a primary role in the down-regulation of MHC-I: GST pulldown assays using recombinant proteins indicated that most of the MHC-I CD and Nef residues that are required for the down-regulation in human cells contribute to direct interactions with a truncated version of micro1. Specifically, the tyrosine residue of the YSQA sequence in the MHC-I CD as well as Nef residues E62-65 and P78 each contributed to the interaction between MHC-I CD/Nef and micro1 in vitro, whereas Nef M20 had little to no role. Conversely, residues F172/D174 and V392/L395 of the binding pocket on micro1 for Yxxphi motifs were required for a robust interaction.These data indicate that the MHC-I cytoplasmic domain, Nef, and the C-terminal two thirds of the mu subunit of AP-1 are sufficient to constitute a biologically relevant interaction. The data also reveal an unexpected role for a hydrophobic pocket in micro1 for interaction with MHC-I CD/Nef.

Short Communication: Accumulation of Neutral Lipids in Liver and Aorta of Nef-Transgenic Mice

OpenAIRE

Pushkarsky, Tatiana; Shilov, Evgeny; Kruglova, Natalya; Naumann, Ronald; Brichacek, Beda; Jennelle, Lucas; Sviridov, Dmitri; Kruglov, Andrei; Nedospasov, Sergei A.; Bukrinsky, Michael

2017-01-01

HIV-infected individuals are at high risk of developing atherosclerosis and cardiovascular disease, in part, due to HIV-induced impairment of cholesterol metabolism. In vitro studies demonstrated that HIV-1 protein Nef inhibits activity of ABCA1, the main cellular cholesterol transporter, leading to cholesterol accumulation in macrophages and conversion of these cells into foam cells, characteristic for atherosclerosis. However, the mechanisms of Nef-mediated effects on cholesterol metabolism...

Solvable model for chimera states of coupled oscillators.

Science.gov (United States)

Abrams, Daniel M; Mirollo, Rennie; Strogatz, Steven H; Wiley, Daniel A

2008-08-22

Networks of identical, symmetrically coupled oscillators can spontaneously split into synchronized and desynchronized subpopulations. Such chimera states were discovered in 2002, but are not well understood theoretically. Here we obtain the first exact results about the stability, dynamics, and bifurcations of chimera states by analyzing a minimal model consisting of two interacting populations of oscillators. Along with a completely synchronous state, the system displays stable chimeras, breathing chimeras, and saddle-node, Hopf, and homoclinic bifurcations of chimeras.

Engineering and Validation of a Vector for Concomitant Expression of Rare Transfer RNA (tRNA and HIV-1 nef Genes in Escherichia coli.

Directory of Open Access Journals (Sweden)

Siti Aisyah Mualif

Full Text Available Relative ease in handling and manipulation of Escherichia coli strains make them primary candidate to express proteins heterologously. Overexpression of heterologous genes that contain codons infrequently used by E. coli is related with difficulties such as mRNA instability, early termination of transcription and/or translation, deletions and/or misincorporation, and cell growth inhibition. These codon bias -associated problems are addressed by co-expressing ColE1-compatible, rare tRNA expressing helper plasmids. However, this approach has inadequacies, which we have addressed by engineering an expression vector that concomitantly expresses the heterologous protein of interest, and rare tRNA genes in E. coli. The expression vector contains three (argU, ileY, leuW rare tRNA genes and a useful multiple cloning site for easy in-frame cloning. To maintain the overall size of the parental plasmid vector, the rare tRNA genes replaced the non-essential DNA segments in the vector. The cloned gene is expressed under the control of T7 promoter and resulting recombinant protein has a C-terminal 6His tag for IMAC-mediated purification. We have evaluated the usefulness of this expression vector by expressing three HIV-1 genes namely HIV-1 p27 (nef, HIV-1 p24 (ca, and HIV-1 vif in NiCo21(DE3 E.coli and demonstrated the advantages of using expression vector that concomitantly expresses rare tRNA and heterologous genes.

Chimera states in three dimensions

International Nuclear Information System (INIS)

Maistrenko, Yuri; Sudakov, Oleksandr; Osiv, Oleksiy; Maistrenko, Volodymyr

2015-01-01

The chimera state is a recently discovered dynamical phenomenon in arrays of nonlocally coupled oscillators, that displays a self-organized spatial pattern of coexisting coherence and incoherence. In this paper, the first evidence of three-dimensional chimera states is reported for the Kuramoto model of phase oscillators in 3D grid topology with periodic boundary conditions. Systematic analysis of the dependence of the spatiotemporal dynamics on the range and strength of coupling shows that there are two principal classes of the chimera patterns which exist in large domains of the parameter space: (I) oscillating and (II) spirally rotating. Characteristic examples from the first class include coherent as well as incoherent balls, tubes, crosses, and layers in incoherent or coherent surrounding; the second class includes scroll waves with incoherent, randomized rolls of different modality and dynamics. Numerical simulations started from various initial conditions indicate that the states are stable over the integration time. Videos of the dynamics of the chimera states are presented in supplementary material. It is concluded that three-dimensional chimera states, which are novel spatiotemporal patterns involving the coexistence of coherent and incoherent domains, can represent one of the inherent features of nature. (paper)

Nefness of adjoint bundles for ample vector bundles

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Hidetoshi Maeda

1995-11-01

Full Text Available Let E be an ample vector bundle of rank >1 on a smooth complex projective variety X of dimension n. This paper gives a classification of pairs (X,E whose adjoint bundles K_X+det E are not nef in the case when  r=n-2.

The Dependence of Chimera States on Initial Conditions

International Nuclear Information System (INIS)

Feng Yue-E; Li Hai-Hong

2015-01-01

A chimera state consisting of both coherent and incoherent groups is a fascinating spatial pattern in non-locally coupled identical oscillators. It is thought that random initial conditions hardly evolve to chimera states. In this work, we study the dependence of chimera states on initial conditions. We show that random initial conditions may lead to chimera states and the chance of realizing chimera states becomes increasing when the model parameters are moving away from the boundary of their stable regime. (paper)

Chimera patterns in the Kuramoto–Battogtokh model

International Nuclear Information System (INIS)

Smirnov, Lev; Osipov, Grigory; Pikovsky, Arkady

2017-01-01

Kuramoto and Battogtokh (2002 Nonlinear Phenom. Complex Syst . 5 380) discovered chimera states represented by stable coexisting synchrony and asynchrony domains in a lattice of coupled oscillators. After a reformulation in terms of a local order parameter, the problem can be reduced to partial differential equations. We find uniformly rotating, spatially periodic chimera patterns as solutions of a reversible ordinary differential equation, and demonstrate a plethora of such states. In the limit of neutral coupling they reduce to analytical solutions in the form of one- and two-point chimera patterns as well as localized chimera solitons. Patterns at weakly attracting coupling are characterized by virtue of a perturbative approach. Stability analysis reveals that only the simplest chimeras with one synchronous region are stable. (letter)

Chimera patterns in the Kuramoto-Battogtokh model

Science.gov (United States)

Smirnov, Lev; Osipov, Grigory; Pikovsky, Arkady

2017-02-01

Kuramoto and Battogtokh (2002 Nonlinear Phenom. Complex Syst. 5 380) discovered chimera states represented by stable coexisting synchrony and asynchrony domains in a lattice of coupled oscillators. After a reformulation in terms of a local order parameter, the problem can be reduced to partial differential equations. We find uniformly rotating, spatially periodic chimera patterns as solutions of a reversible ordinary differential equation, and demonstrate a plethora of such states. In the limit of neutral coupling they reduce to analytical solutions in the form of one- and two-point chimera patterns as well as localized chimera solitons. Patterns at weakly attracting coupling are characterized by virtue of a perturbative approach. Stability analysis reveals that only the simplest chimeras with one synchronous region are stable.

Interaction with the Src homology (SH3-SH2) region of the Src-family kinase Hck structures the HIV-1 Nef dimer for kinase activation and effector recruitment.

Science.gov (United States)

Alvarado, John Jeff; Tarafdar, Sreya; Yeh, Joanne I; Smithgall, Thomas E

2014-10-10

HIV-1 Nef supports high titer viral replication in vivo and is essential for AIDS progression. Nef function depends on interactions with multiple host cell effectors, including Hck and other Src-family kinases. Here we describe the x-ray crystal structure of Nef in complex with the Hck SH3-SH2 regulatory region to a resolution of 1.86 Å. The complex crystallized as a dimer of complexes, with the conserved Nef PXXPXR motif engaging the Hck SH3 domain. A new intercomplex contact was found between SH3 Glu-93, and Nef Arg-105. Mutagenesis of Hck SH3 Glu-93 interfered with Nef·Hck complex formation and kinase activation in cells. The Hck SH2 domains impinge on the N-terminal region of Nef to stabilize a dimer conformation that exposes Asp-123, a residue critical for Nef function. Our results suggest that in addition to serving as a kinase effector for Nef, Hck binding may reorganize the Nef dimer for functional interaction with other signaling partners. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

Interaction with the Src Homology (SH3-SH2) Region of the Src-family Kinase Hck Structures the HIV-1 Nef Dimer for Kinase Activation and Effector Recruitment*

Science.gov (United States)

Alvarado, John Jeff; Tarafdar, Sreya; Yeh, Joanne I.; Smithgall, Thomas E.

2014-01-01

HIV-1 Nef supports high titer viral replication in vivo and is essential for AIDS progression. Nef function depends on interactions with multiple host cell effectors, including Hck and other Src-family kinases. Here we describe the x-ray crystal structure of Nef in complex with the Hck SH3-SH2 regulatory region to a resolution of 1.86 Å. The complex crystallized as a dimer of complexes, with the conserved Nef PXXPXR motif engaging the Hck SH3 domain. A new intercomplex contact was found between SH3 Glu-93, and Nef Arg-105. Mutagenesis of Hck SH3 Glu-93 interfered with Nef·Hck complex formation and kinase activation in cells. The Hck SH2 domains impinge on the N-terminal region of Nef to stabilize a dimer conformation that exposes Asp-123, a residue critical for Nef function. Our results suggest that in addition to serving as a kinase effector for Nef, Hck binding may reorganize the Nef dimer for functional interaction with other signaling partners. PMID:25122770

Enhancing UCSF Chimera through web services.

Science.gov (United States)

Huang, Conrad C; Meng, Elaine C; Morris, John H; Pettersen, Eric F; Ferrin, Thomas E

2014-07-01

Integrating access to web services with desktop applications allows for an expanded set of application features, including performing computationally intensive tasks and convenient searches of databases. We describe how we have enhanced UCSF Chimera (http://www.rbvi.ucsf.edu/chimera/), a program for the interactive visualization and analysis of molecular structures and related data, through the addition of several web services (http://www.rbvi.ucsf.edu/chimera/docs/webservices.html). By streamlining access to web services, including the entire job submission, monitoring and retrieval process, Chimera makes it simpler for users to focus on their science projects rather than data manipulation. Chimera uses Opal, a toolkit for wrapping scientific applications as web services, to provide scalable and transparent access to several popular software packages. We illustrate Chimera's use of web services with an example workflow that interleaves use of these services with interactive manipulation of molecular sequences and structures, and we provide an example Python program to demonstrate how easily Opal-based web services can be accessed from within an application. Web server availability: http://webservices.rbvi.ucsf.edu/opal2/dashboard?command=serviceList. © The Author(s) 2014. Published by Oxford University Press on behalf of Nucleic Acids Research.

Chimera states in bipartite networks of FitzHugh-Nagumo oscillators

Science.gov (United States)

Wu, Zhi-Min; Cheng, Hong-Yan; Feng, Yuee; Li, Hai-Hong; Dai, Qiong-Lin; Yang, Jun-Zhong

2018-04-01

Chimera states consisting of spatially coherent and incoherent domains have been observed in different topologies such as rings, spheres, and complex networks. In this paper, we investigate bipartite networks of nonlocally coupled FitzHugh-Nagumo (FHN) oscillators in which the units are allocated evenly to two layers, and FHN units interact with each other only when they are in different layers. We report the existence of chimera states in bipartite networks. Owing to the interplay between chimera states in the two layers, many types of chimera states such as in-phase chimera states, antiphase chimera states, and out-of-phase chimera states are classified. Stability diagrams of several typical chimera states in the coupling strength-coupling radius plane, which show strong multistability of chimera states, are explored.

Chimeras taking shape: Potential functions of proteins encoded by chimeric RNA transcripts

Science.gov (United States)

Frenkel-Morgenstern, Milana; Lacroix, Vincent; Ezkurdia, Iakes; Levin, Yishai; Gabashvili, Alexandra; Prilusky, Jaime; del Pozo, Angela; Tress, Michael; Johnson, Rory; Guigo, Roderic; Valencia, Alfonso

2012-01-01

Chimeric RNAs comprise exons from two or more different genes and have the potential to encode novel proteins that alter cellular phenotypes. To date, numerous putative chimeric transcripts have been identified among the ESTs isolated from several organisms and using high throughput RNA sequencing. The few corresponding protein products that have been characterized mostly result from chromosomal translocations and are associated with cancer. Here, we systematically establish that some of the putative chimeric transcripts are genuinely expressed in human cells. Using high throughput RNA sequencing, mass spectrometry experimental data, and functional annotation, we studied 7424 putative human chimeric RNAs. We confirmed the expression of 175 chimeric RNAs in 16 human tissues, with an abundance varying from 0.06 to 17 RPKM (Reads Per Kilobase per Million mapped reads). We show that these chimeric RNAs are significantly more tissue-specific than non-chimeric transcripts. Moreover, we present evidence that chimeras tend to incorporate highly expressed genes. Despite the low expression level of most chimeric RNAs, we show that 12 novel chimeras are translated into proteins detectable in multiple shotgun mass spectrometry experiments. Furthermore, we confirm the expression of three novel chimeric proteins using targeted mass spectrometry. Finally, based on our functional annotation of exon organization and preserved domains, we discuss the potential features of chimeric proteins with illustrative examples and suggest that chimeras significantly exploit signal peptides and transmembrane domains, which can alter the cellular localization of cognate proteins. Taken together, these findings establish that some chimeric RNAs are translated into potentially functional proteins in humans. PMID:22588898

Immunogenic compositions comprising human immunodeficiency virus (HIV) mosaic Nef proteins

Science.gov (United States)

Korber, Bette T [Los Alamos, NM; Perkins, Simon [Los Alamos, NM; Bhattacharya, Tanmoy [Los Alamos, NM; Fischer, William M [Los Alamos, NM; Theiler, James [Los Alamos, NM; Letvin, Norman [Boston, MA; Haynes, Barton F [Durham, NC; Hahn, Beatrice H [Birmingham, AL; Yusim, Karina [Los Alamos, NM; Kuiken, Carla [Los Alamos, NM

2012-02-21

The present invention relates to mosaic clade M HIV-1 Nef polypeptides and to compositions comprising same. The polypeptides of the invention are suitable for use in inducing an immune response to HIV-1 in a human.

Growth promotion of genetically modified hematopoietic progenitors using an antibody/c-Mpl chimera.

Science.gov (United States)

Kawahara, Masahiro; Chen, Jianhong; Sogo, Takahiro; Teng, Jinying; Otsu, Makoto; Onodera, Masafumi; Nakauchi, Hiromitsu; Ueda, Hiroshi; Nagamune, Teruyuki

2011-09-01

Thrombopoietin is a potent cytokine that exerts proliferation of hematopoietic stem cells (HSCs) through its cognate receptor, c-Mpl. Therefore, mimicry of c-Mpl signaling by a receptor recognizing an artificial ligand would be attractive to attain specific expansion of genetically modified HSCs. Here we propose a system enabling selective expansion of genetically modified cells using an antibody/receptor chimera that can be activated by a specific antigen. We constructed an antibody/c-Mpl chimera, in which single-chain Fv (ScFv) of an anti-fluorescein antibody was tethered to the extracellular D2 domain of the erythropoietin receptor and transmembrane/cytoplasmic domains of c-Mpl. When the chimera was expressed in interleukin (IL)-3-dependent pro-B cell line Ba/F3, genetically modified cells were selectively expanded in the presence of fluorescein-conjugated BSA (BSA-FL) as a specific antigen. Furthermore, highly purified mouse HSCs transduced with the retrovirus carrying antibody/c-Mpl chimera gene proliferated in vitro in response to BSA-FL, and the cells retained in vivo long-term repopulating abilities. These results demonstrate that the antibody/c-Mpl chimera is capable of signal transduction that mimics wild-type c-Mpl signaling. Copyright © 2011 Elsevier Ltd. All rights reserved.

Refining the intrinsic chimera flap: a review.

Science.gov (United States)

Agarwal, Jayant P; Agarwal, Shailesh; Adler, Neta; Gottlieb, Lawrence J

2009-10-01

Reconstruction of complex tissue deficiencies in which each missing component is in a different spatial relationship to each other can be particularly challenging, especially in patients with limited recipient vessels. The chimera flap design is uniquely suited to reconstruct these deformities. Chimera flaps have been previously defined in many ways with 2 main categories: prefabricated or intrinsic. Herein we attempt to clarify the definition of a true intrinsic chimeric flap and provide examples of how these constructs provide a method for reconstruction of complex defects. The versatility of the intrinsic chimera flap and its procurement from 7 different vascular systems is described. A clarification of the definition of a true intrinsic chimera flap is described. In addition, construction of flaps from the lateral femoral circumflex, deep circumflex iliac, inferior gluteal, peroneal, subscapular, thoracodorsal, and radial arterial systems is described to showcase the versatility of these chimera flaps. A true intrinsic chimera flap must consist of more than a single tissue type. Each of the tissue components receives its blood flow from separate vascular branches or perforators that are connected to a single vascular source. These vascular branches must be of appropriate length to allow for insetting with 3-dimensional spatial freedom. There are a multitude of sites from which true intrinsic chimera flaps may be harvested.

Quantum walk on a chimera graph

Science.gov (United States)

Xu, Shu; Sun, Xiangxiang; Wu, Jizhou; Zhang, Wei-Wei; Arshed, Nigum; Sanders, Barry C.

2018-05-01

We analyse a continuous-time quantum walk on a chimera graph, which is a graph of choice for designing quantum annealers, and we discover beautiful quantum walk features such as localization that starkly distinguishes classical from quantum behaviour. Motivated by technological thrusts, we study continuous-time quantum walk on enhanced variants of the chimera graph and on diminished chimera graph with a random removal of vertices. We explain the quantum walk by constructing a generating set for a suitable subgroup of graph isomorphisms and corresponding symmetry operators that commute with the quantum walk Hamiltonian; the Hamiltonian and these symmetry operators provide a complete set of labels for the spectrum and the stationary states. Our quantum walk characterization of the chimera graph and its variants yields valuable insights into graphs used for designing quantum-annealers.

HIV-1 Nef induces proinflammatory state in macrophages through its acidic cluster domain: involvement of TNF alpha receptor associated factor 2.

Directory of Open Access Journals (Sweden)

Giorgio Mangino

Full Text Available BACKGROUND: HIV-1 Nef is a virulence factor that plays multiple roles during HIV replication. Recently, it has been described that Nef intersects the CD40 signalling in macrophages, leading to modification in the pattern of secreted factors that appear able to recruit, activate and render T lymphocytes susceptible to HIV infection. The engagement of CD40 by CD40L induces the activation of different signalling cascades that require the recruitment of specific tumor necrosis factor receptor-associated factors (i.e. TRAFs. We hypothesized that TRAFs might be involved in the rapid activation of NF-κB, MAPKs and IRF-3 that were previously described in Nef-treated macrophages to induce the synthesis and secretion of proinflammatory cytokines, chemokines and IFNβ to activate STAT1, -2 and -3. METHODOLOGY/PRINCIPAL FINDINGS: Searching for possible TRAF binding sites on Nef, we found a TRAF2 consensus binding site in the AQEEEE sequence encompassing the conserved four-glutamate acidic cluster. Here we show that all the signalling effects we observed in Nef treated macrophages depend on the integrity of the acidic cluster. In addition, Nef was able to interact in vitro with TRAF2, but not TRAF6, and this interaction involved the acidic cluster. Finally silencing experiments in THP-1 monocytic cells indicate that both TRAF2 and, surprisingly, TRAF6 are required for the Nef-induced tyrosine phosphorylation of STAT1 and STAT2. CONCLUSIONS: Results reported here revealed TRAF2 as a new possible cellular interactor of Nef and highlighted that in monocytes/macrophages this viral protein is able to manipulate both the TRAF/NF-κB and TRAF/IRF-3 signalling axes, thereby inducing the synthesis of proinflammatory cytokines and chemokines as well as IFNβ.

Chimera States in Neural Oscillators

Science.gov (United States)

Bahar, Sonya; Glaze, Tera

2014-03-01

Chimera states have recently been explored both theoretically and experimentally, in various coupled nonlinear oscillators, ranging from phase-oscillator models to coupled chemical reactions. In a chimera state, both coherent and incoherent (or synchronized and desynchronized) states occur simultaneously in populations of identical oscillators. We investigate chimera behavior in a population of neural oscillators using the Huber-Braun model, a Hodgkin-Huxley-like model originally developed to characterize the temperature-dependent bursting behavior of mammalian cold receptors. One population of neurons is allowed to synchronize, with each neuron receiving input from all the others in its group (global within-group coupling). Subsequently, a second population of identical neurons is placed under an identical global within-group coupling, and the two populations are also coupled to each other (between-group coupling). For certain values of the coupling constants, the neurons in the two populations exhibit radically different synchronization behavior. We will discuss the range of chimera activity in the model, and discuss its implications for actual neural activity, such as unihemispheric sleep.

Synthesis of periclinal chimera in cassava.

Science.gov (United States)

Nassar, N M A; Bomfim, N

2013-02-27

We provide the first report on the synthesis of a very productive interspecific periclinal chimera of cassava, with large and edible roots. The epidermal tissue of the chimera was formed by the cultivated species Manihot esculenta (E), and the subepidermis and internal tissue were formed by the wild species, Manihot fortalezensis (F). We used cytogenetics and morphological analyses to determine the origins of all tissues. These results may offer potential for the development of new lines for crop improvement based on the use of chimera composed of different combinations of wild species and cultivars.

Clustered chimera states in systems of type-I excitability

International Nuclear Information System (INIS)

Vüllings, Andrea; Omelchenko, Iryna; Hövel, Philipp; Hizanidis, Johanne

2014-01-01

The chimera state is a fascinating phenomenon of coexisting synchronized and desynchronized behaviour that was discovered in networks of nonlocally coupled identical phase oscillators over ten years ago. Since then, chimeras have been found in numerous theoretical and experimental studies and more recently in models of neuronal dynamics as well. In this work, we consider a generic model for a saddle-node bifurcation on a limit cycle representative of neural excitability type I. We obtain chimera states with multiple coherent regions (clustered chimeras/multi-chimeras) depending on the distance from the excitability threshold, the range of nonlocal coupling and the coupling strength. A detailed stability diagram for these chimera states and other interesting coexisting patterns (like traveling waves) is presented. (paper)

Generalized synchronization between chimera states

Science.gov (United States)

Andrzejak, Ralph G.; Ruzzene, Giulia; Malvestio, Irene

2017-05-01

Networks of coupled oscillators in chimera states are characterized by an intriguing interplay of synchronous and asynchronous motion. While chimera states were initially discovered in mathematical model systems, there is growing experimental and conceptual evidence that they manifest themselves also in natural and man-made networks. In real-world systems, however, synchronization and desynchronization are not only important within individual networks but also across different interacting networks. It is therefore essential to investigate if chimera states can be synchronized across networks. To address this open problem, we use the classical setting of ring networks of non-locally coupled identical phase oscillators. We apply diffusive drive-response couplings between pairs of such networks that individually show chimera states when there is no coupling between them. The drive and response networks are either identical or they differ by a variable mismatch in their phase lag parameters. In both cases, already for weak couplings, the coherent domain of the response network aligns its position to the one of the driver networks. For identical networks, a sufficiently strong coupling leads to identical synchronization between the drive and response. For non-identical networks, we use the auxiliary system approach to demonstrate that generalized synchronization is established instead. In this case, the response network continues to show a chimera dynamics which however remains distinct from the one of the driver. Hence, segregated synchronized and desynchronized domains in individual networks congregate in generalized synchronization across networks.

A New Approximate Chimera Donor Cell Search Algorithm

Science.gov (United States)

Holst, Terry L.; Nixon, David (Technical Monitor)

1998-01-01

The objectives of this study were to develop chimera-based full potential methodology which is compatible with overflow (Euler/Navier-Stokes) chimera flow solver and to develop a fast donor cell search algorithm that is compatible with the chimera full potential approach. Results of this work included presenting a new donor cell search algorithm suitable for use with a chimera-based full potential solver. This algorithm was found to be extremely fast and simple producing donor cells as fast as 60,000 per second.

Time-delayed feedback control of coherence resonance chimeras

Science.gov (United States)

Zakharova, Anna; Semenova, Nadezhda; Anishchenko, Vadim; Schöll, Eckehard

2017-11-01

Using the model of a FitzHugh-Nagumo system in the excitable regime, we investigate the influence of time-delayed feedback on noise-induced chimera states in a network with nonlocal coupling, i.e., coherence resonance chimeras. It is shown that time-delayed feedback allows for the control of the range of parameter values where these chimera states occur. Moreover, for the feedback delay close to the intrinsic period of the system, we find a novel regime which we call period-two coherence resonance chimera.

Antibody responses in allogeneic radiation chimeras

International Nuclear Information System (INIS)

Coico, R.F.

1982-01-01

The construction of long-lived allogeneic radiation chimeras, free of graft-versus-host disease, has been achieved using serologic elimination of Thy 1 + cells from donor bone marrow. Humoral immune function was not restored in these animals as evidenced by lack of primary antibody responses to a T cell-dependent antigen, namely, sheep erythrocytes (SRBC) both in vivo and in vitro. No evidence for a suppressor cell-mediated mechanism was found. Using separated chimera spleen cell populations and specific helper cell soluble mediators, the functional capabilities of chimera B cells, T cells, and macrophages were assessed. These findings suggested that the failure of chimeras to produce antibody is not the result of impaired B cell, T cell, or macrophage function, but rather, that it is due to ineffective cellular interactions. Physiologic cellular interactions depend upon the sharing of major histocompatibility complex (MHC) determinants between interacting cells. However, the self-recognition repertoire of developing T cells may be influenced by the environment which these cells differentiate such that they learn to recognize host MHC determinants as self. These findings support the interpretation that the immunologic hyporeactivity of allogeneic bone marrow chimeras reflects the role of the host environment in restricting the interactive capabilities of donor-derived cells

Prototype and Chimera-Type Galectins in Placentas with Spontaneous and Recurrent Miscarriages.

Science.gov (United States)

Unverdorben, Laura; Haufe, Thomas; Santoso, Laura; Hofmann, Simone; Jeschke, Udo; Hutter, Stefan

2016-04-28

Galectins are galactose binding proteins and, in addition, factors for a wide range of pathologies in pregnancy. We have analyzed the expression of prototype (gal-1, -2, -7, -10) and chimera-type (gal-3) galectins in the placenta in cases of spontaneous abortions (SPA) and recurrent abortions (RA) in the first trimester. Fifteen placental samples from healthy pregnancies were used as a control group. Nine placentas were examined for spontaneous abortions, and 12 placentas for recurrent abortions. For differentiation and evaluation of different cell types of galectin-expression in the decidua, immunofluorescence was used. For all investigated prototype galectins (gal-1, -2, -7, -10) in SPA and RA placenta trophoblast cells the expression is significantly decreased. In the decidua/extravillous trophoblast only gal-2 expression was significantly lowered, which could be connected to its role in angiogenesis. In trophoblasts in first-trimester placentas and in cases of SPA and RA, prototype galectins are altered in the same way. We suspect prototype galectins have a similar function in placental tissue because of their common biochemical structure. Expression of galectin 3 as a chimera type galectin was not found to be significantly altered in abortive placentas.

A Phase I Double Blind, Placebo-Controlled, Randomized Study of the Safety and Immunogenicity of an Adjuvanted HIV-1 Gag-Pol-Nef Fusion Protein and Adenovirus 35 Gag-RT-Int-Nef Vaccine in Healthy HIV-Uninfected African Adults.

Directory of Open Access Journals (Sweden)

Gloria Omosa-Manyonyi

Full Text Available Sequential prime-boost or co-administration of HIV vaccine candidates based on an adjuvanted clade B p24, RT, Nef, p17 fusion protein (F4/AS01 plus a non-replicating adenovirus 35 expressing clade A Gag, RT, Int and Nef (Ad35-GRIN may lead to a unique immune profile, inducing both strong T-cell and antibody responses.In a phase 1, double-blind, placebo-controlled trial, 146 healthy adult volunteers were randomized to one of four regimens: heterologous prime-boost with two doses of F4/AS01E or F4/AS01B followed by Ad35-GRIN; Ad35-GRIN followed by two doses of F4/AS01B; or three co-administrations of Ad35-GRIN and F4/AS01B. T cell and antibody responses were measured.The vaccines were generally well-tolerated, and did not cause serious adverse events. The response rate, by IFN-γ ELISPOT, was greater when Ad35-GRIN was the priming vaccine and in the co-administration groups. F4/AS01 induced CD4+ T-cells expressing primarily CD40L and IL2 +/- TNF-α, while Ad35-GRIN induced predominantly CD8+ T-cells expressing IFN-γ +/- IL2 or TNF-α. Viral inhibition was induced after Ad35-GRIN vaccination, regardless of the regimen. Strong F4-specific antibody responses were induced. Immune responses persisted at least a year after the last vaccination. The complementary response profiles, characteristic of each vaccine, were both expressed after co-administration.Co-administration of an adjuvanted protein and an adenovirus vector showed an acceptable safety and reactogenicity profile and resulted in strong, multifunctional and complementary HIV-specific immune responses.ClinicalTrials.gov NCT01264445.

Sequence- and interactome-based prediction of viral protein hotspots targeting host proteins: a case study for HIV Nef.

Directory of Open Access Journals (Sweden)

Mahdi Sarmady

Full Text Available Virus proteins alter protein pathways of the host toward the synthesis of viral particles by breaking and making edges via binding to host proteins. In this study, we developed a computational approach to predict viral sequence hotspots for binding to host proteins based on sequences of viral and host proteins and literature-curated virus-host protein interactome data. We use a motif discovery algorithm repeatedly on collections of sequences of viral proteins and immediate binding partners of their host targets and choose only those motifs that are conserved on viral sequences and highly statistically enriched among binding partners of virus protein targeted host proteins. Our results match experimental data on binding sites of Nef to host proteins such as MAPK1, VAV1, LCK, HCK, HLA-A, CD4, FYN, and GNB2L1 with high statistical significance but is a poor predictor of Nef binding sites on highly flexible, hoop-like regions. Predicted hotspots recapture CD8 cell epitopes of HIV Nef highlighting their importance in modulating virus-host interactions. Host proteins potentially targeted or outcompeted by Nef appear crowding the T cell receptor, natural killer cell mediated cytotoxicity, and neurotrophin signaling pathways. Scanning of HIV Nef motifs on multiple alignments of hepatitis C protein NS5A produces results consistent with literature, indicating the potential value of the hotspot discovery in advancing our understanding of virus-host crosstalk.

In vivo differentiation of induced pluripotent stem cells into neural stem cells by chimera formation.

Science.gov (United States)

Choi, Hyun Woo; Hong, Yean Ju; Kim, Jong Soo; Song, Hyuk; Cho, Ssang Gu; Bae, Hojae; Kim, Changsung; Byun, Sung June; Do, Jeong Tae

2017-01-01

Like embryonic stem cells, induced pluripotent stem cells (iPSCs) can differentiate into all three germ layers in an in vitro system. Here, we developed a new technology for obtaining neural stem cells (NSCs) from iPSCs through chimera formation, in an in vivo environment. iPSCs contributed to the neural lineage in the chimera, which could be efficiently purified and directly cultured as NSCs in vitro. The iPSC-derived, in vivo-differentiated NSCs expressed NSC markers, and their gene-expression pattern more closely resembled that of fetal brain-derived NSCs than in vitro-differentiated NSCs. This system could be applied for differentiating pluripotent stem cells into specialized cell types whose differentiation protocols are not well established.

T cells from fully H-2 allogeneic (A replaced by B) radiation bone marrow chimeras are functionally competent and host restricted but are alloreactive against hybrid Ia determinants expressed on (A x B)F1 cells

International Nuclear Information System (INIS)

Kruisbeek, A.M.; Hathcock, K.S.; Hodes, R.J.; Singer, A.

1982-01-01

In this communication it is demonstrated that T cells from fully allogeneic A replaced by B radiation bone marrow chimeras are alloreactive against the hybrid Ia molecules expressed on the surface of heterozygous A X B cells. These results suggested that previous failures to generate cytotoxic T lymphocyte (CTL) responses from fully allogeneic chimeras by sensitizing the chimeric T cells to antigen in an (A X B)F1-priming environment might have been confounded by an ongoing alloreaction against determinants created by hybrid Ia molecules expressed on F1 cells. Consequently, the ability to generate CTL responses from fully allogeneic chimeras was re-examined by sensitizing the chimeric T cells to antigen presented by homozygous rather that F1 stimulator cells. It was found that T cells of donor bone marrow origin that mediate cytotoxic responses to trinitrophenyl-modified self determinants do differentiate into functional competence in an H-2-incompatible host environment and are restricted to the host H-2 haplotype

Chimera Grid Tools

Science.gov (United States)

Chan, William M.; Rogers, Stuart E.; Nash, Steven M.; Buning, Pieter G.; Meakin, Robert

2005-01-01

Chimera Grid Tools (CGT) is a software package for performing computational fluid dynamics (CFD) analysis utilizing the Chimera-overset-grid method. For modeling flows with viscosity about geometrically complex bodies in relative motion, the Chimera-overset-grid method is among the most computationally cost-effective methods for obtaining accurate aerodynamic results. CGT contains a large collection of tools for generating overset grids, preparing inputs for computer programs that solve equations of flow on the grids, and post-processing of flow-solution data. The tools in CGT include grid editing tools, surface-grid-generation tools, volume-grid-generation tools, utility scripts, configuration scripts, and tools for post-processing (including generation of animated images of flows and calculating forces and moments exerted on affected bodies). One of the tools, denoted OVERGRID, is a graphical user interface (GUI) that serves to visualize the grids and flow solutions and provides central access to many other tools. The GUI facilitates the generation of grids for a new flow-field configuration. Scripts that follow the grid generation process can then be constructed to mostly automate grid generation for similar configurations. CGT is designed for use in conjunction with a computer-aided-design program that provides the geometry description of the bodies, and a flow-solver program.

Double-well chimeras in 2D lattice of chaotic bistable elements

Science.gov (United States)

Shepelev, I. A.; Bukh, A. V.; Vadivasova, T. E.; Anishchenko, V. S.; Zakharova, A.

2018-01-01

We investigate spatio-temporal dynamics of a 2D ensemble of nonlocally coupled chaotic cubic maps in a bistability regime. In particular, we perform a detailed study on the transition ;coherence - incoherence; for varying coupling strength for a fixed interaction radius. For the 2D ensemble we show the appearance of amplitude and phase chimera states previously reported for 1D ensembles of nonlocally coupled chaotic systems. Moreover, we uncover a novel type of chimera state, double-well chimera, which occurs due to the interplay of the bistability of the local dynamics and the 2D ensemble structure. Additionally, we find double-well chimera behavior for steady states which we call double-well chimera death. A distinguishing feature of chimera patterns observed in the lattice is that they mainly combine clusters of different chimera types: phase, amplitude and double-well chimeras.

Chimera states in mechanical oscillator networks.

Science.gov (United States)

Martens, Erik Andreas; Thutupalli, Shashi; Fourrière, Antoine; Hallatschek, Oskar

2013-06-25

The synchronization of coupled oscillators is a fascinating manifestation of self-organization that nature uses to orchestrate essential processes of life, such as the beating of the heart. Although it was long thought that synchrony and disorder were mutually exclusive steady states for a network of identical oscillators, numerous theoretical studies in recent years have revealed the intriguing possibility of "chimera states," in which the symmetry of the oscillator population is broken into a synchronous part and an asynchronous part. However, a striking lack of empirical evidence raises the question of whether chimeras are indeed characteristic of natural systems. This calls for a palpable realization of chimera states without any fine-tuning, from which physical mechanisms underlying their emergence can be uncovered. Here, we devise a simple experiment with mechanical oscillators coupled in a hierarchical network to show that chimeras emerge naturally from a competition between two antagonistic synchronization patterns. We identify a wide spectrum of complex states, encompassing and extending the set of previously described chimeras. Our mathematical model shows that the self-organization observed in our experiments is controlled by elementary dynamical equations from mechanics that are ubiquitous in many natural and technological systems. The symmetry-breaking mechanism revealed by our experiments may thus be prevalent in systems exhibiting collective behavior, such as power grids, optomechanical crystals, or cells communicating via quorum sensing in microbial populations.

Numerical analysis of the chimera states in the multilayered network model

Science.gov (United States)

Goremyko, Mikhail V.; Maksimenko, Vladimir A.; Makarov, Vladimir V.; Ghosh, Dibakar; Bera, Bidesh K.; Dana, Syamal K.; Hramov, Alexander E.

2017-03-01

We numerically study the interaction between the ensembles of the Hindmarsh-Rose (HR) neuron systems, arranged in the multilayer network model. We have shown that the fully identical layers, demonstrated individually different chimera due to the initial mismatch, come to the identical chimera state with the increase of inter-layer coupling. Within the multilayer model we also consider the case, when the one layer demonstrates chimera state, while another layer exhibits coherent or incoherent dynamics. It has been shown that the interactions chimera-coherent state and chimera-incoherent state leads to the both excitation of chimera as from the ensemble of fully coherent or incoherent oscillators, and suppression of initially stable chimera state

Implementing real-time robotic systems using CHIMERA II

Science.gov (United States)

Stewart, David B.; Schmitz, Donald E.; Khosla, Pradeep K.

1990-01-01

A description is given of the CHIMERA II programming environment and operating system, which was developed for implementing real-time robotic systems. Sensor-based robotic systems contain both general- and special-purpose hardware, and thus the development of applications tends to be a time-consuming task. The CHIMERA II environment is designed to reduce the development time by providing a convenient software interface between the hardware and the user. CHIMERA II supports flexible hardware configurations which are based on one or more VME-backplanes. All communication across multiple processors is transparent to the user through an extensive set of interprocessor communication primitives. CHIMERA II also provides a high-performance real-time kernel which supports both deadline and highest-priority-first scheduling. The flexibility of CHIMERA II allows hierarchical models for robot control, such as NASREM, to be implemented with minimal programming time and effort.

Bistable Chimera Attractors on a Triangular Network of Oscillator Populations

DEFF Research Database (Denmark)

Martens, Erik Andreas

2010-01-01

. This triangular network is the simplest discretization of a continuous ring of oscillators. Yet it displays an unexpectedly different behavior: in contrast to the lone stable chimera observed in continuous rings of oscillators, we find that this system exhibits two coexisting stable chimeras. Both chimeras are......, as usual, born through a saddle-node bifurcation. As the coupling becomes increasingly local in nature they lose stability through a Hopf bifurcation, giving rise to breathing chimeras, which in turn get destroyed through a homoclinic bifurcation. Remarkably, one of the chimeras reemerges by a reversal...

77 FR 65602 - Chimera Energy Corporation; Order of Suspension of Trading

Science.gov (United States)

2012-10-29

... SECURITIES AND EXCHANGE COMMISSION [File No. 500-1] Chimera Energy Corporation; Order of... lack of current and accurate information concerning the securities of Chimera Energy Corporation (``Chimera'') because of questions regarding the accuracy of statements by Chimera in press releases to...

Breathing chimera in a system of phase oscillators

Science.gov (United States)

Bolotov, M. I.; Smirnov, L. A.; Osipov, G. V.; Pikovsky, A. S.

2017-09-01

Chimera states consisting of synchronous and asynchronous domains in a medium of nonlinearly coupled phase oscillators have been considered. Stationary inhomogeneous solutions of the Ott-Antonsen equation for a complex order parameter that correspond to fundamental chimeras have been constructed. The direct numerical simulation has shown that these structures under certain conditions are transformed to oscillatory (breathing) chimera regimes because of the development of instability.

Persistent chimera states in nonlocally coupled phase oscillators

OpenAIRE

Suda, Yusuke; Okuda, Koji

2015-01-01

Chimera states in the systems of nonlocally coupled phase oscillators are considered stable in the continuous limit of spatially distributed oscillators. However, it is reported that in the numerical simulations without taking such limit, chimera states are chaotic transient and finally collapse into the completely synchronous solution. In this Rapid Communication, we numerically study chimera states by using the coupling function different from the previous studies and obtain the result that...

Assay using embryo aggregation chimeras for the detection of nonlethal changes in X-irradiated mouse preimplantation embryos

International Nuclear Information System (INIS)

Obasaju, M.F.; Wiley, L.M.; Oudiz, D.J.; Miller, L.; Samuels, S.J.; Chang, R.J.; Overstreet, J.W.

1988-01-01

We have developed a short-term in vitro assay for the detection of sublethal effects produced by very low levels of ionizing radiation. The assay utilizes mouse embryo aggregation chimeras consisting of one irradiated embryo paired with an unirradiated embryo whose blastomeres have been labeled with fluorescein isothiocyanate (FITC). X irradiation (from 0.05 to 2 Gy) and chimera construction were performed with four-cell stage embryos, and the chimeras were cultured for 40 h to the morula stage. The morulae were partially dissociated with calcium-free culture medium and viewed under phase contrast and epifluorescence microscopy to obtain total embryo cell number and the cellular contribution of irradiated (unlabeled) and control (FITC labeled) embryos per chimera. In chimeras where neither embryo was irradiated, the ratio of the unlabeled blastomeres to the total number of blastomeres per chimera embryo was 0.50 (17.8 +/- 5.6 cells per unlabeled embryo and 17.4 +/- 5.5 cells per FITC-labeled partner embryo). However, in chimeras formed after the unlabeled embryos were irradiated with as little as 0.05 Gy, the ratio of unlabeled blastomeres to the total number of blastomeres per chimera embryo was 0.43 (P less than 0.01). The apparent decreases in cell proliferation were not observed in irradiated embryos that were merely cocultured with control embryos, regardless of whether the embryos were zona enclosed or zona free. We conclude that very low levels of radiation induce sublethal changes in cleaving embryos that are expressed as a proliferative disadvantage within two cell cycles when irradiated embryos are in direct cell-to-cell contact with unirradiated embryos

Chimera states in nonlocally coupled phase oscillators with biharmonic interaction

Science.gov (United States)

Cheng, Hongyan; Dai, Qionglin; Wu, Nianping; Feng, Yuee; Li, Haihong; Yang, Junzhong

2018-03-01

Chimera states, which consist of coexisting domains of coherent and incoherent parts, have been observed in a variety of systems. Most of previous works on chimera states have taken into account specific form of interaction between oscillators, for example, sinusoidal coupling or diffusive coupling. Here, we investigate chimera dynamics in nonlocally coupled phase oscillators with biharmonic interaction. We find novel chimera states with features such as that oscillators in the same coherent cluster may split into two groups with a phase difference around π/2 and that oscillators in adjacent coherent clusters may have a phase difference close to π/2. The different impacts of the coupling ranges in the first and the second harmonic interactions on chimera dynamics are investigated based on the synchronous dynamics in globally coupled phase oscillators. Our study suggests a new direction in the field of chimera dynamics.

Persistence of attenuated HIV-1 rev alleles in an epidemiologically linked cohort of long-term survivors infected with nef-deleted virus

Directory of Open Access Journals (Sweden)

Wesselingh Steven L

2007-07-01

Full Text Available Abstract Background The Sydney blood bank cohort (SBBC of long-term survivors consists of multiple individuals infected with nef-deleted, attenuated strains of human immunodeficiency virus type 1 (HIV-1. Although the cohort members have experienced differing clinical courses and now comprise slow progressors (SP as well as long-term nonprogressors (LTNP, longitudinal analysis of nef/long-terminal repeat (LTR sequences demonstrated convergent nef/LTR sequence evolution in SBBC SP and LTNP. Thus, the in vivo pathogenicity of attenuated HIV-1 strains harboured by SBBC members is dictated by factors other than nef/LTR. Therefore, to determine whether defects in other viral genes contribute to attenuation of these HIV-1 strains, we characterized dominant HIV-1 rev alleles that persisted in 4 SBBC subjects; C18, C64, C98 and D36. Results The ability of Rev derived from D36 and C64 to bind the Rev responsive element (RRE in RNA binding assays was reduced by approximately 90% compared to Rev derived from HIV-1NL4-3, C18 or C98. D36 Rev also had a 50–60% reduction in ability to express Rev-dependent reporter constructs in mammalian cells. In contrast, C64 Rev had only marginally decreased Rev function despite attenuated RRE binding. In D36 and C64, attenuated RRE binding was associated with rare amino acid changes at 3 highly conserved residues; Gln to Pro at position 74 immediately N-terminal to the Rev activation domain, and Val to Leu and Ser to Pro at positions 104 and 106 at the Rev C-terminus, respectively. In D36, reduced Rev function was mapped to an unusual 13 amino acid extension at the Rev C-terminus. Conclusion These findings provide new genetic and mechanistic insights important for Rev function, and suggest that Rev function, not Rev/RRE binding may be rate limiting for HIV-1 replication. In addition, attenuated rev alleles may contribute to viral attenuation and long-term survival of HIV-1 infection in a subset of SBBC members.

Optimal design of tweezer control for chimera states

Science.gov (United States)

Omelchenko, Iryna; Omel'chenko, Oleh E.; Zakharova, Anna; Schöll, Eckehard

2018-01-01

Chimera states are complex spatio-temporal patterns which consist of coexisting domains of spatially coherent and incoherent dynamics in systems of coupled oscillators. In small networks, chimera states usually exhibit short lifetimes and erratic drifting of the spatial position of the incoherent domain. A tweezer feedback control scheme can stabilize and fix the position of chimera states. We analyze the action of the tweezer control in small nonlocally coupled networks of Van der Pol and FitzHugh-Nagumo oscillators, and determine the ranges of optimal control parameters. We demonstrate that the tweezer control scheme allows for stabilization of chimera states with different shapes, and can be used as an instrument for controlling the coherent domains size, as well as the maximum average frequency difference of the oscillators.

Phenotype and envelope gene diversity of nef-deleted HIV-1 isolated from long-term survivors infected from a single source

Directory of Open Access Journals (Sweden)

Sullivan John S

2007-07-01

Full Text Available Abstract Background The Sydney blood bank cohort (SBBC of long-term survivors consists of multiple individuals infected with attenuated, nef-deleted variants of human immunodeficiency virus type 1 (HIV-1 acquired from a single source. Long-term prospective studies have demonstrated that the SBBC now comprises slow progressors (SP as well as long-term nonprogressors (LTNP. Convergent evolution of nef sequences in SBBC SP and LTNP indicates the in vivo pathogenicity of HIV-1 in SBBC members is dictated by factors other than nef. To better understand mechanisms underlying the pathogenicity of nef-deleted HIV-1, we examined the phenotype and env sequence diversity of sequentially isolated viruses (n = 2 from 3 SBBC members. Results The viruses characterized here were isolated from two SP spanning a three or six year period during progressive HIV-1 infection (subjects D36 and C98, respectively and from a LTNP spanning a two year period during asymptomatic, nonprogressive infection (subject C18. Both isolates from D36 were R5X4 phenotype and, compared to control HIV-1 strains, replicated to low levels in peripheral blood mononuclear cells (PBMC. In contrast, both isolates from C98 and C18 were CCR5-restricted. Both viruses isolated from C98 replicated to barely detectable levels in PBMC, whereas both viruses isolated from C18 replicated to low levels, similar to those isolated from D36. Analysis of env by V1V2 and V3 heteroduplex tracking assay, V1V2 length polymorphisms, sequencing and phylogenetic analysis showed distinct intra- and inter-patient env evolution. Conclusion Independent evolution of env despite convergent evolution of nef may contribute to the in vivo pathogenicity of nef-deleted HIV-1 in SBBC members, which may not necessarily be associated with changes in replication capacity or viral coreceptor specificity.

α-Peptide/ß-Peptoid Chimeras

DEFF Research Database (Denmark)

Olsen, Christian Adam; Bonke, Gitte; Vedel, Line

2007-01-01

We describe the synthesis and characterization of the first generation of oligomers consisting of alternating repeats of a-amino acids and chiral N-alkyl-ß-alanine (ß-peptoid) residues. These chimeras are stable toward proteolysis, non-hemolytic, and possess antibacterial activity comparable...... to well-known antimicrobial agents. Moreover, the chimeras exhibit length-dependent, concentration-dependent, solvent-dependent, and ion-strength-dependent ellipticity, indicating the presence of a secondary structure in solution. Thus, a-peptide/ß-peptoid oligomers represent a promising novel...

nef gene sequence variation among HIV-1-infected African children

Czech Academy of Sciences Publication Activity Database

Chakraborty, R.; Reiniš, Milan; Rostron, T.; Philpott, S.; Dong, T.; D'Agostino, A.; Musoke, R.; de Silva, E.; Stumpf, M.; Weiser, B.; Burger, H.; Rowland-Jones, S.L.

2006-01-01

Roč. 7, č. 2 (2006), s. 75-84 ISSN 1464-2662 Grant - others:Fogarty International Center, NIH(US) 3D43TW00915; NIH(US) RO1 AI 42555 Institutional research plan: CEZ:AV0Z50520514 Keywords : HIV-1 nef gene * non-clade B * Kenya Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 2.674, year: 2006

Engineering human cytochrome P450 enzymes into catalytically self-sufficient chimeras using molecular Lego.

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Dodhia, Vikash Rajnikant; Fantuzzi, Andrea; Gilardi, Gianfranco

2006-10-01

The membrane-bound human cytochrome P450s have essential roles in the metabolism of endogenous compounds and drugs. Presented here are the results on the construction and characterization of three fusion proteins containing the N-terminally modified human cytochrome P450s CYP2C9, CY2C19 and CYP3A4 fused to the soluble NADPH-dependent oxidoreductase domain of CYP102A1 from Bacillus megaterium. The constructs, CYP2C9/BMR, CYP2C19/BMR and CYP3A4/BMR are well expressed in Escherichia coli as holo proteins. The chimeras can be purified in the absence of detergent and the purified enzymes are both active and correctly folded in the absence of detergent, as demonstrated by circular dichroism and functional studies. Additionally, in comparison with the parent P450 enzyme, these chimeras have greatly improved solubility properties. The chimeras are catalytically self-sufficient and present turnover rates similar to those reported for the native enzymes in reconstituted systems, unlike previously reported mammalian cytochrome P450 fusion proteins. Furthermore the specific activities of these chimeras are not dependent on the enzyme concentration present in the reaction buffer and they do not require the addition of accessory proteins, detergents or phospholipids to be fully active. The solubility, catalytic self-sufficiency and wild-type like activities of these chimeras would greatly simplify the studies of cytochrome P450 mediated drug metabolism in solution.

Symmetries of Chimera States

Science.gov (United States)

Kemeth, Felix P.; Haugland, Sindre W.; Krischer, Katharina

2018-05-01

Symmetry broken states arise naturally in oscillatory networks. In this Letter, we investigate chaotic attractors in an ensemble of four mean-coupled Stuart-Landau oscillators with two oscillators being synchronized. We report that these states with partially broken symmetry, so-called chimera states, have different setwise symmetries in the incoherent oscillators, and in particular, some are and some are not invariant under a permutation symmetry on average. This allows for a classification of different chimera states in small networks. We conclude our report with a discussion of related states in spatially extended systems, which seem to inherit the symmetry properties of their counterparts in small networks.

Is repulsion good for the health of chimeras?

Science.gov (United States)

Jalan, Sarika; Ghosh, Saptarshi; Patra, Bibhabasu

2017-10-01

Yes! Very much so. A chimera state refers to the coexistence of a coherent-incoherent dynamical evolution of identically coupled oscillators. We investigate the impact of multiplexing of a layer having repulsively coupled oscillators on the occurrence of chimeras in the layer having attractively coupled identical oscillators. We report that there exists an enhancement in the appearance of the chimera state in one layer of the multiplex network in the presence of repulsive coupling in the other layer. Furthermore, we show that a small amount of inhibition or repulsive coupling in one layer is sufficient to yield the chimera state in another layer by destroying its synchronized behavior. These results can be used to obtain insight into dynamical behaviors of those systems where both attractive and repulsive couplings exist among their constituents.

Chimera regimes in a ring of oscillators with local nonlinear interaction

Science.gov (United States)

Shepelev, Igor A.; Zakharova, Anna; Vadivasova, Tatiana E.

2017-03-01

One of important problems concerning chimera states is the conditions of their existence and stability. Until now, it was assumed that chimeras could arise only in ensembles with nonlocal character of interactions. However, this assumption is not exactly right. In some special cases chimeras can be realized for local type of coupling [1-3]. We propose a simple model of ensemble with local coupling when chimeras are realized. This model is a ring of linear oscillators with the local nonlinear unidirectional interaction. Chimera structures in the ring are found using computer simulations for wide area of values of parameters. Diagram of the regimes on plane of control parameters is plotted and scenario of chimera destruction are studied when the parameters are changed.

Metaphysical and ethical perspectives on creating animal-human chimeras.

Science.gov (United States)

Eberl, Jason T; Ballard, Rebecca A

2009-10-01

This paper addresses several questions related to the nature, production, and use of animal-human (a-h) chimeras. At the heart of the issue is whether certain types of a-h chimeras should be brought into existence, and, if they are, how we should treat such creatures. In our current research environment, we recognize a dichotomy between research involving nonhuman animal subjects and research involving human subjects, and the classification of a research protocol into one of these categories will trigger different ethical standards as to the moral permissibility of the research in question. Are a-h chimeras entitled to the more restrictive and protective ethical standards applied to human research subjects? We elucidate an Aristotelian-Thomistic metaphysical framework in which to argue how such chimeras ought to be defined ontologically. We then examine when the creation of, and experimentation upon, certain types of a-h chimeras may be morally permissible.

The chimera state in colloidal phase oscillators with hydrodynamic interaction

Science.gov (United States)

Hamilton, Evelyn; Bruot, Nicolas; Cicuta, Pietro

2017-12-01

The chimera state is the incongruous situation where coherent and incoherent populations coexist in sets of identical oscillators. Using driven non-linear oscillators interacting purely through hydrodynamic forces at low Reynolds number, previously studied as a simple model of motile cilia supporting waves, we find concurrent incoherent and synchronised subsets in small arrays. The chimeras seen in simulation display a "breathing" aspect, reminiscent of uniformly interacting phase oscillators. In contrast to other systems where chimera has been observed, this system has a well-defined interaction metric, and we know that the emergent dynamics inherit the symmetry of the underlying Oseen tensor eigenmodes. The chimera state can thus be connected to a superposition of eigenstates, whilst considering the mean interaction strength within and across subsystems allows us to make a connection to more generic (and abstract) chimeras in populations of Kuramoto phase oscillators. From this work, we expect the chimera state to emerge in experimental observations of oscillators coupled through hydrodynamic forces.

Characterization of host lymphoid cells in antibody-facilitated bone marrow chimeras

International Nuclear Information System (INIS)

McCarthy, S.A.; Griffith, I.J.; Gambel, P.; Francescutti, L.H.; Wegmann, T.G.

1985-01-01

The authors have produced stable murine antibody-facilitated (AF) chimeras by the simultaneous injection of P1 bone marrow cells and anti-P2 monoclonal antibody into normal (unirradiated) adult (P1 X P2)F1 recipients. These AF chimeras are healthy, long-lived, and exhibit no overt signs of graft-versus-host disease. They are immunocompetent and tolerant of host, P2-encoded alloantigens. Donor cell engraftment and takeover, monitored by glucosephosphate isomerase isozyme patterns, is usually complete (greater than 95%) in the peripheral blood, bone marrow, and hemopoietic stem cell compartments of long-term (greater than 3 months posttransplantation) AF chimeras. The authors report here, however, that splenic, lymph node, and thymic leukocytes of AF chimeras represent donor/host chimeric populations. Spleen cell populations of AF chimeras exhibit substantial chimera-to-chimera variation in the preponderant residual host cell type(s) present. Interpretations of the implications of these findings are discussed

Connecting the Kuramoto Model and the Chimera State

Science.gov (United States)

Kotwal, Tejas; Jiang, Xin; Abrams, Daniel M.

2017-12-01

Since its discovery in 2002, the chimera state has frequently been described as a counterintuitive, puzzling phenomenon. The Kuramoto model, in contrast, has become a celebrated paradigm useful for understanding a range of phenomena related to phase transitions, synchronization, and network effects. Here we show that the chimera state can be understood as emerging naturally through a symmetry-breaking bifurcation from the Kuramoto model's partially synchronized state. Our analysis sheds light on recent observations of chimera states in laser arrays, chemical oscillators, and mechanical pendula.

DNAzyme-mediated recovery of small recombinant RNAs from a 5S rRNA-derived chimera expressed in Escherichia coli

Directory of Open Access Journals (Sweden)

Willson Richard C

2010-12-01

Full Text Available Abstract Background Manufacturing large quantities of recombinant RNAs by overexpression in a bacterial host is hampered by their instability in intracellular environment. To overcome this problem, an RNA of interest can be fused into a stable bacterial RNA for the resulting chimeric construct to accumulate in the cytoplasm to a sufficiently high level. Being supplemented with cost-effective procedures for isolation of the chimera from cells and recovery of the recombinant RNA from stabilizing scaffold, this strategy might become a viable alternative to the existing methods of chemical or enzymatic RNA synthesis. Results Sequence encoding a 71-nucleotide recombinant RNA was inserted into a plasmid-borne deletion mutant of the Vibrio proteolyticus 5S rRNA gene in place of helix III - loop C segment of the original 5S rRNA. After transformation into Escherichia coli, the chimeric RNA (3×pen aRNA was expressed constitutively from E. coli rrnB P1 and P2 promoters. The RNA chimera accumulated to levels that exceeded those of the host's 5S rRNA. A novel method relying on liquid-solid partitioning of cellular constituents was developed for isolation of total RNA from bacterial cells. This protocol avoids toxic chemicals, and is therefore more suitable for large scale RNA purification than traditional methods. A pair of biotinylated 8-17 DNAzymes was used to bring about the quantitative excision of the 71-nt recombinant RNA from the chimera. The recombinant RNA was isolated by sequence-specific capture on beads with immobilized complementary deoxyoligonucleotide, while DNAzymes were recovered by biotin affinity chromatography for reuse. Conclusions The feasibility of a fermentation-based approach for manufacturing large quantities of small RNAs in vivo using a "5S rRNA scaffold" strategy is demonstrated. The approach provides a route towards an economical method for the large-scale production of small RNAs including shRNAs, siRNAs and aptamers for use

Petascale supernova simulation with CHIMERA

Energy Technology Data Exchange (ETDEWEB)

Messer, O E B [National Center for Computational Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6008 (United States); Bruenn, S W [Department of Physics, Florida Atlantic University, 777 W Glades Road, Boca Raton, FL 33431-0991 (United States); Blondin, J M [Department of Physics, North Carolina State University, Raleigh, NC 27695-8202 (United States); Hix, W R [Physics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6354 (United States); Mezzacappa, A [Physics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6354 (United States); Dirk, C J [Department of Physics, Florida Atlantic University, 777 W Glades Road, Boca Raton, FL 33431-0991 (United States)

2007-07-15

CHIMERA is a multi-dimensional radiation hydrodynamics code designed to study core-collapse supernovae. The code is made up of three essentially independent parts: a hydrodynamics module, a nuclear burning module, and a neutrino transport solver combined within an operator-split approach. We describe some major algorithmic facets of the code and briefly discuss some recent results. The multi-physics nature of the problem, and the specific implementation of that physics in CHIMERA, provide a rather straightforward path to effective use of multi-core platforms in the near future.

Preliminary results of Digital Pulse Shape Acquisition from Chimera

International Nuclear Information System (INIS)

Alderighi, D.M.; Sechi, G.; Anzalone, A.; Cavallaro, S.; Giustolisi, F.; Laguidara, E.; Lanzalone, G.; Porto, F.; Bassini, R.; Boiano, C.; Guazzoni, P.; Russo, S.; Sassi, M.; Zetta, L.; Cardella, G.; Defilippo, S.E.; Lanzano, G.; Paganod, A.; Papa, M.; Pirrone, S.; Politi, G.; Geraci, E.

2003-01-01

A 100 MS/s 14-bit Sampling Analog-to-Digital converter has been used to perform digital pulse-shape acquisition of signals collected from CHIMERA telescopes. The signals from a typical CHIMERA detection cell have been collected using both a standard CHIMERA electronic chain up to the amplifier, and a very simple analog front end, basically reduced to the preamplifier. The preliminary on-beam results are presented. (authors)

Preliminary results of Digital Pulse Shape Acquisition from Chimera

Energy Technology Data Exchange (ETDEWEB)

Alderighi, D.M.; Sechi, G. [INFN Milano and IASF, CNR, Milano (France); Anzalone, A.; Cavallaro, S.; Giustolisi, F.; Laguidara, E.; Lanzalone, G.; Porto, F. [Catania Univ., LNS and Dipartimento di Fisica (France); Bassini, R.; Boiano, C.; Guazzoni, P.; Russo, S.; Sassi, M.; Zetta, L. [Milano Univ., INFN and Dipartimento di Fisica (Italy); Cardella, G.; Defilippo, S.E.; Lanzano, G.; Paganod, A.; Papa, M.; Pirrone, S.; Politi, G. [Catania Univ., INFN and Dipartimento di Fisica (Italy); Geraci, E. [Bologna Univ., INFN and Dipartimento di Fisica (Italy)

2003-07-01

A 100 MS/s 14-bit Sampling Analog-to-Digital converter has been used to perform digital pulse-shape acquisition of signals collected from CHIMERA telescopes. The signals from a typical CHIMERA detection cell have been collected using both a standard CHIMERA electronic chain up to the amplifier, and a very simple analog front end, basically reduced to the preamplifier. The preliminary on-beam results are presented. (authors)

Chimera states in networks of logistic maps with hierarchical connectivities

Science.gov (United States)

zur Bonsen, Alexander; Omelchenko, Iryna; Zakharova, Anna; Schöll, Eckehard

2018-04-01

Chimera states are complex spatiotemporal patterns consisting of coexisting domains of coherence and incoherence. We study networks of nonlocally coupled logistic maps and analyze systematically how the dilution of the network links influences the appearance of chimera patterns. The network connectivities are constructed using an iterative Cantor algorithm to generate fractal (hierarchical) connectivities. Increasing the hierarchical level of iteration, we compare the resulting spatiotemporal patterns. We demonstrate that a high clustering coefficient and symmetry of the base pattern promotes chimera states, and asymmetric connectivities result in complex nested chimera patterns.

Chimera States in Two Populations with Heterogeneous Phase-lag

DEFF Research Database (Denmark)

Martens, Erik Andreas; Bick, Christian; Panaggio, Mark

2016-01-01

The simplest network of coupled phase-oscillators exhibiting chimera states is given by two populations with disparate intra- and inter-population coupling strengths. We explore the effects of heterogeneous coupling phase-lags between the two populations. Such heterogeneity arises naturally......-uniform synchronization, including in-phase and anti-phase synchrony, full incoherence (splay state), chimera states with phase separation of 0 or π between populations, and states where both populations remain desynchronized. These desynchronized states exhibit stable, oscillatory, and even chaotic dynamics. Moreover......, we identify the bifurcations through which chimera and desynchronized states emerge. Stable chimera states and desynchronized solutions, which do not arise for homogeneous phase-lag parameters, emerge as a result of competition between synchronized in-phase, anti-phase equilibria, and fully...

Generation of axolotl hematopoietic chimeras

Directory of Open Access Journals (Sweden)

David Lopez

2015-02-01

Full Text Available Wound repair is an extremely complex process that requires precise coordination between various cell types including immune cells.  Unfortunately, in mammals this usually results in scar formation instead of restoration of the original fully functional tissue, otherwise known as regeneration.  Various animal models like frogs and salamanders are currently being studied to determine the intracellular and intercellular pathways, controlled by gene expression, that elicit cell proliferation, differentiation, and migration of cells during regenerative healing.  Now, the necessary genetic tools to map regenerative pathways are becoming available for the axolotl salamander, thus allowing comparative studies between scarring and regeneration.  Here, we describe in detail three methods to produce axolotl hematopoietic cell-tagged chimeras for the study of hematopoiesis and regeneration.

Chimera states in coupled Kuramoto oscillators with inertia

International Nuclear Information System (INIS)

Olmi, Simona

2015-01-01

The dynamics of two symmetrically coupled populations of rotators is studied for different values of the inertia. The system is characterized by different types of solutions, which all coexist with the fully synchronized state. At small inertia, the system is no more chaotic and one observes mainly quasi-periodic chimeras, while the usual (stationary) chimera state is not anymore observable. At large inertia, one observes two different kind of chaotic solutions with broken symmetry: the intermittent chaotic chimera, characterized by a synchronized population and a population displaying a turbulent behaviour, and a second state where the two populations are both chaotic but whose dynamics adhere to two different macroscopic attractors. The intermittent chaotic chimeras are characterized by a finite life-time, whose duration increases as a power-law with the system size and the inertia value. Moreover, the chaotic population exhibits clear intermittent behavior, displaying a laminar phase where the two populations tend to synchronize, and a turbulent phase where the macroscopic motion of one population is definitely erratic. In the thermodynamic limit, these states survive for infinite time and the laminar regimes tends to disappear, thus giving rise to stationary chaotic solutions with broken symmetry contrary to what observed for chaotic chimeras on a ring geometry

Chimera states in coupled Kuramoto oscillators with inertia

Energy Technology Data Exchange (ETDEWEB)

Olmi, Simona, E-mail: simona.olmi@fi.isc.cnr.it [CNR - Consiglio Nazionale delle Ricerche - Istituto dei Sistemi Complessi, via Madonna del Piano 10, I-50019 Sesto Fiorentino (Italy); INFN Sez. Firenze, via Sansone, 1 - I-50019 Sesto Fiorentino (Italy)

2015-12-15

The dynamics of two symmetrically coupled populations of rotators is studied for different values of the inertia. The system is characterized by different types of solutions, which all coexist with the fully synchronized state. At small inertia, the system is no more chaotic and one observes mainly quasi-periodic chimeras, while the usual (stationary) chimera state is not anymore observable. At large inertia, one observes two different kind of chaotic solutions with broken symmetry: the intermittent chaotic chimera, characterized by a synchronized population and a population displaying a turbulent behaviour, and a second state where the two populations are both chaotic but whose dynamics adhere to two different macroscopic attractors. The intermittent chaotic chimeras are characterized by a finite life-time, whose duration increases as a power-law with the system size and the inertia value. Moreover, the chaotic population exhibits clear intermittent behavior, displaying a laminar phase where the two populations tend to synchronize, and a turbulent phase where the macroscopic motion of one population is definitely erratic. In the thermodynamic limit, these states survive for infinite time and the laminar regimes tends to disappear, thus giving rise to stationary chaotic solutions with broken symmetry contrary to what observed for chaotic chimeras on a ring geometry.

Chimera states in coupled Kuramoto oscillators with inertia.

Science.gov (United States)

Olmi, Simona

2015-12-01

The dynamics of two symmetrically coupled populations of rotators is studied for different values of the inertia. The system is characterized by different types of solutions, which all coexist with the fully synchronized state. At small inertia, the system is no more chaotic and one observes mainly quasi-periodic chimeras, while the usual (stationary) chimera state is not anymore observable. At large inertia, one observes two different kind of chaotic solutions with broken symmetry: the intermittent chaotic chimera, characterized by a synchronized population and a population displaying a turbulent behaviour, and a second state where the two populations are both chaotic but whose dynamics adhere to two different macroscopic attractors. The intermittent chaotic chimeras are characterized by a finite life-time, whose duration increases as a power-law with the system size and the inertia value. Moreover, the chaotic population exhibits clear intermittent behavior, displaying a laminar phase where the two populations tend to synchronize, and a turbulent phase where the macroscopic motion of one population is definitely erratic. In the thermodynamic limit, these states survive for infinite time and the laminar regimes tends to disappear, thus giving rise to stationary chaotic solutions with broken symmetry contrary to what observed for chaotic chimeras on a ring geometry.

Chimera states: Effects of different coupling topologies

Science.gov (United States)

Bera, Bidesh K.; Majhi, Soumen; Ghosh, Dibakar; Perc, Matjaž

2017-04-01

Collective behavior among coupled dynamical units can emerge in various forms as a result of different coupling topologies as well as different types of coupling functions. Chimera states have recently received ample attention as a fascinating manifestation of collective behavior, in particular describing a symmetry breaking spatiotemporal pattern where synchronized and desynchronized states coexist in a network of coupled oscillators. In this perspective, we review the emergence of different chimera states, focusing on the effects of different coupling topologies that describe the interaction network connecting the oscillators. We cover chimera states that emerge in local, nonlocal and global coupling topologies, as well as in modular, temporal and multilayer networks. We also provide an outline of challenges and directions for future research.

Chimera states in a Hodgkin-Huxley model of thermally sensitive neurons

Science.gov (United States)

Glaze, Tera A.; Lewis, Scott; Bahar, Sonya

2016-08-01

Chimera states occur when identically coupled groups of nonlinear oscillators exhibit radically different dynamics, with one group exhibiting synchronized oscillations and the other desynchronized behavior. This dynamical phenomenon has recently been studied in computational models and demonstrated experimentally in mechanical, optical, and chemical systems. The theoretical basis of these states is currently under active investigation. Chimera behavior is of particular relevance in the context of neural synchronization, given the phenomenon of unihemispheric sleep and the recent observation of asymmetric sleep in human patients with sleep apnea. The similarity of neural chimera states to neural "bump" states, which have been suggested as a model for working memory and visual orientation tuning in the cortex, adds to their interest as objects of study. Chimera states have been demonstrated in the FitzHugh-Nagumo model of excitable cells and in the Hindmarsh-Rose neural model. Here, we demonstrate chimera states and chimera-like behaviors in a Hodgkin-Huxley-type model of thermally sensitive neurons both in a system with Abrams-Strogatz (mean field) coupling and in a system with Kuramoto (distance-dependent) coupling. We map the regions of parameter space for which chimera behavior occurs in each of the two coupling schemes.

Deterministic and stochastic control of chimera states in delayed feedback oscillator

Energy Technology Data Exchange (ETDEWEB)

Semenov, V. [Department of Physics, Saratov State University, Astrakhanskaya Str. 83, 410012 Saratov (Russian Federation); Zakharova, A.; Schöll, E. [Institut für Theoretische Physik, TU Berlin, Hardenbergstraße 36, 10623 Berlin (Germany); Maistrenko, Y. [Institute of Mathematics and Center for Medical and Biotechnical Research, NAS of Ukraine, Tereschenkivska Str. 3, 01601 Kyiv (Ukraine)

2016-06-08

Chimera states, characterized by the coexistence of regular and chaotic dynamics, are found in a nonlinear oscillator model with negative time-delayed feedback. The control of these chimera states by external periodic forcing is demonstrated by numerical simulations. Both deterministic and stochastic external periodic forcing are considered. It is shown that multi-cluster chimeras can be achieved by adjusting the external forcing frequency to appropriate resonance conditions. The constructive role of noise in the formation of a chimera states is shown.

Spiral wave chimera states in large populations of coupled chemical oscillators

Science.gov (United States)

Totz, Jan Frederik; Rode, Julian; Tinsley, Mark R.; Showalter, Kenneth; Engel, Harald

2018-03-01

The coexistence of coherent and incoherent dynamics in a population of identically coupled oscillators is known as a chimera state1,2. Discovered in 20023, this counterintuitive dynamical behaviour has inspired extensive theoretical and experimental activity4-15. The spiral wave chimera is a particularly remarkable chimera state, in which an ordered spiral wave rotates around a core consisting of asynchronous oscillators. Spiral wave chimeras were theoretically predicted in 200416 and numerically studied in a variety of systems17-23. Here, we report their experimental verification using large populations of nonlocally coupled Belousov-Zhabotinsky chemical oscillators10,18 in a two-dimensional array. We characterize previously unreported spatiotemporal dynamics, including erratic motion of the asynchronous spiral core, growth and splitting of the cores, as well as the transition from the chimera state to disordered behaviour. Spiral wave chimeras are likely to occur in other systems with long-range interactions, such as cortical tissues24, cilia carpets25, SQUID metamaterials26 and arrays of optomechanical oscillators9.

Mechanisms of tolerance in murine radiation bone marrow chimeras. I. Nonspecific suppression of alloreactivity by spleen cells from early, but not late, chimeras

International Nuclear Information System (INIS)

Auchincloss, H. Jr.; Sachs, D.H.

1983-01-01

Allogeneic chimeras were prepared using lethally irradiated B6 hosts and untreated marrow from exsanguinated BALB/c donors. For about two months after reconstitution, chimeras had very weak antihost cell-mediated lymphocytotoxicity (CML) reactivity and little third-party alloreactivity. During this time a cell population capable of suppressing CML reactivity against both host and third-party alloantigens (i.e., antigen-nonspecific) was demonstrated in chimera spleens by in vitro mixing experiments. The putative suppressor cells were Thy-1-negative and radiation-sensitive. Subsequently, mature chimeras showed host tolerance and strong third-party alloreactivity. At this point suppressor mechanisms could no longer be demonstrated. These data are consistent with a clonal elimination hypothesis in that they do not provide evidence to indicate that maintenance of specific immune tolerance is mediated by an active suppressor mechanism

Stable amplitude chimera states in a network of locally coupled Stuart-Landau oscillators

Science.gov (United States)

Premalatha, K.; Chandrasekar, V. K.; Senthilvelan, M.; Lakshmanan, M.

2018-03-01

We investigate the occurrence of collective dynamical states such as transient amplitude chimera, stable amplitude chimera, and imperfect breathing chimera states in a locally coupled network of Stuart-Landau oscillators. In an imperfect breathing chimera state, the synchronized group of oscillators exhibits oscillations with large amplitudes, while the desynchronized group of oscillators oscillates with small amplitudes, and this behavior of coexistence of synchronized and desynchronized oscillations fluctuates with time. Then, we analyze the stability of the amplitude chimera states under various circumstances, including variations in system parameters and coupling strength, and perturbations in the initial states of the oscillators. For an increase in the value of the system parameter, namely, the nonisochronicity parameter, the transient chimera state becomes a stable chimera state for a sufficiently large value of coupling strength. In addition, we also analyze the stability of these states by perturbing the initial states of the oscillators. We find that while a small perturbation allows one to perturb a large number of oscillators resulting in a stable amplitude chimera state, a large perturbation allows one to perturb a small number of oscillators to get a stable amplitude chimera state. We also find the stability of the transient and stable amplitude chimera states and traveling wave states for an appropriate number of oscillators using Floquet theory. In addition, we also find the stability of the incoherent oscillation death states.

Plant chimeras: The good, the bad, and the 'Bizzaria'.

Science.gov (United States)

Frank, Margaret H; Chitwood, Daniel H

2016-11-01

Chimeras - organisms that are composed of cells of more than one genotype - captured the human imagination long before they were formally described and used in the laboratory. These organisms owe their namesake to a fire-breathing monster from Greek mythology that has the head of a lion, the body of a goat, and the tail of a serpent. The first description of a non-fictional chimera dates back to the middle of the seventeenth century when the Florentine gardener Pietro Nati discovered an adventitious shoot growing from the graft junction between sour orange (Citrus aurantium) and citron (Citrus medica). This perplexing chimera that grows with sectors phenotypically resembling each of the citrus progenitors inspired discussion and wonder from the scientific community and was fittingly named the 'Bizzaria'. Initially, the 'Bizzaria' was believed to be an asexual hybrid that formed from a cellular fusion between the grafted parents; however, in-depth cellular analyses carried out centuries later demonstrated that the 'Bizzaria', along with other chimeras, owe their unique sectored appearance to a conglomeration of cells from the two donors. Since this pivotal discovery at the turn of the twentieth century, chimeras have served both as tools and as unique biological phenomena that have contributed to our understanding of plant development at the cellular, tissue, and organismal level. Rapid advancements in genome sequencing technologies have enabled the establishment of new model species with novel morphological and developmental features that enable the generation of chimeric organisms. In this review, we show that genetic mosaic and chimera studies provide a technologically simple way to delve into the organismal, genetic, and genomic inner workings underlying the development of diverse model organisms. Moreover, we discuss the unique opportunity that chimeras present to explore universal principles governing intercellular communication and the coordination of

Identification of SIV Nef CD8(+) T cell epitopes restricted by a MHC class I haplotype associated with lower viral loads in a macaque AIDS model.

Science.gov (United States)

Nomura, Takushi; Yamamoto, Hiroyuki; Takahashi, Naofumi; Naruse, Taeko K; Kimura, Akinori; Matano, Tetsuro

2014-07-25

Virus-specific CD8(+) T-cell responses are crucial for the control of human immunodeficiency virus (HIV) and simian immunodeficiency virus (SIV) replication. Multiple studies on HIV-infected individuals and SIV-infected macaques have indicated association of several major histocompatibility complex class I (MHC-I) genotypes with lower viral loads and delayed AIDS progression. Understanding of the viral control mechanism associated with these MHC-I genotypes would contribute to the development of intervention strategy for HIV control. We have previously reported a rhesus MHC-I haplotype, 90-120-Ia, associated with lower viral loads after SIVmac239 infection. Gag206-216 and Gag241-249 epitope-specific CD8(+) T-cell responses have been shown to play a central role in the reduction of viral loads, whereas the effect of Nef-specific CD8(+) T-cell responses induced in all the 90-120-Ia(+) macaques on SIV replication remains unknown. Here, we identified three CD8(+) T-cell epitopes, Nef9-19, Nef89-97, and Nef193-203, associated with 90-120-Ia. Nef9-19 and Nef193-203 epitope-specific CD8(+) T-cell responses frequently selected for mutations resulting in viral escape from recognition by these CD8(+) T cells, indicating that these CD8(+) T cells exert strong suppressive pressure on SIV replication. Results would be useful for elucidation of the viral control mechanism associated with 90-120-Ia. Copyright © 2014 Elsevier Inc. All rights reserved.

Simple and complex chimera states in a nonlinearly coupled oscillatory medium

Science.gov (United States)

Bolotov, Maxim; Smirnov, Lev; Osipov, Grigory; Pikovsky, Arkady

2018-04-01

We consider chimera states in a one-dimensional medium of nonlinear nonlocally coupled phase oscillators. In terms of a local coarse-grained complex order parameter, the problem of finding stationary rotating nonhomogeneous solutions reduces to a third-order ordinary differential equation. This allows finding chimera-type and other inhomogeneous states as periodic orbits of this equation. Stability calculations reveal that only some of these states are stable. We demonstrate that an oscillatory instability leads to a breathing chimera, for which the synchronous domain splits into subdomains with different mean frequencies. Further development of instability leads to turbulent chimeras.

Progress in Grid Generation: From Chimera to DRAGON Grids

Science.gov (United States)

Liou, Meng-Sing; Kao, Kai-Hsiung

1994-01-01

Hybrid grids, composed of structured and unstructured grids, combines the best features of both. The chimera method is a major stepstone toward a hybrid grid from which the present approach is evolved. The chimera grid composes a set of overlapped structured grids which are independently generated and body-fitted, yielding a high quality grid readily accessible for efficient solution schemes. The chimera method has been shown to be efficient to generate a grid about complex geometries and has been demonstrated to deliver accurate aerodynamic prediction of complex flows. While its geometrical flexibility is attractive, interpolation of data in the overlapped regions - which in today's practice in 3D is done in a nonconservative fashion, is not. In the present paper we propose a hybrid grid scheme that maximizes the advantages of the chimera scheme and adapts the strengths of the unstructured grid while at the same time keeps its weaknesses minimal. Like the chimera method, we first divide up the physical domain by a set of structured body-fitted grids which are separately generated and overlaid throughout a complex configuration. To eliminate any pure data manipulation which does not necessarily follow governing equations, we use non-structured grids only to directly replace the region of the arbitrarily overlapped grids. This new adaptation to the chimera thinking is coined the DRAGON grid. The nonstructured grid region sandwiched between the structured grids is limited in size, resulting in only a small increase in memory and computational effort. The DRAGON method has three important advantages: (1) preserving strengths of the chimera grid; (2) eliminating difficulties sometimes encountered in the chimera scheme, such as the orphan points and bad quality of interpolation stencils; and (3) making grid communication in a fully conservative and consistent manner insofar as the governing equations are concerned. To demonstrate its use, the governing equations are

Resistance to infection with Eimeria vermiformis in mouse radiation chimeras is determined by donor bone-marrow cells

International Nuclear Information System (INIS)

Joysey, H.S.; Wakelin, D.; Rose, M.E.

1988-01-01

The course of infection with Eimeria vermiformis was determined in BALB/b, BALB/c, and C57BL/10ScSn (B10) mice and in radiation chimeras prepared from the H-2-compatible BALB/b and B10 mice. The BALB strains, irrespective of H-2 haplotype, were resistant, the B10 mice were susceptible, and in the chimeras infection was characterized by the genotype of the donated bone-marrow cells and not by the phenotype of the recipient. Thus, the genetic control of relative resistance or susceptibility to infection with this parasite is expressed through bone-marrow-derived cells

Germline competence of mouse ES and iPS cell lines: Chimera technologies and genetic background.

Science.gov (United States)

Carstea, Ana Claudia; Pirity, Melinda K; Dinnyes, Andras

2009-12-31

In mice, gene targeting by homologous recombination continues to play an essential role in the understanding of functional genomics. This strategy allows precise location of the site of transgene integration and is most commonly used to ablate gene expression ("knock-out"), or to introduce mutant or modified alleles at the locus of interest ("knock-in"). The efficacy of producing live, transgenic mice challenges our understanding of this complex process, and of the factors which influence germline competence of embryonic stem cell lines. Increasingly, evidence indicates that culture conditions and in vitro manipulation can affect the germline-competence of Embryonic Stem cell (ES cell) lines by accumulation of chromosome abnormalities and/or epigenetic alterations of the ES cell genome. The effectiveness of ES cell derivation is greatly strain-dependent and it may also influence the germline transmission capability. Recent technical improvements in the production of germline chimeras have been focused on means of generating ES cells lines with a higher germline potential. There are a number of options for generating chimeras from ES cells (ES chimera mice); however, each method has its advantages and disadvantages. Recent developments in induced pluripotent stem (iPS) cell technology have opened new avenues for generation of animals from genetically modified somatic cells by means of chimera technologies. The aim of this review is to give a brief account of how the factors mentioned above are influencing the germline transmission capacity and the developmental potential of mouse pluripotent stem cell lines. The most recent methods for generating specifically ES and iPS chimera mice, including the advantages and disadvantages of each method are also discussed.

Chimera states and the interplay between initial conditions and non-local coupling

Science.gov (United States)

Kalle, Peter; Sawicki, Jakub; Zakharova, Anna; Schöll, Eckehard

2017-03-01

Chimera states are complex spatio-temporal patterns that consist of coexisting domains of coherent and incoherent dynamics. We study chimera states in a network of non-locally coupled Stuart-Landau oscillators. We investigate the impact of initial conditions in combination with non-local coupling. Based on an analytical argument, we show how the coupling phase and the coupling strength are linked to the occurrence of chimera states, flipped profiles of the mean phase velocity, and the transition from a phase- to an amplitude-mediated chimera state.

Chimera states in two-dimensional networks of locally coupled oscillators

Science.gov (United States)

Kundu, Srilena; Majhi, Soumen; Bera, Bidesh K.; Ghosh, Dibakar; Lakshmanan, M.

2018-02-01

Chimera state is defined as a mixed type of collective state in which synchronized and desynchronized subpopulations of a network of coupled oscillators coexist and the appearance of such anomalous behavior has strong connection to diverse neuronal developments. Most of the previous studies on chimera states are not extensively done in two-dimensional ensembles of coupled oscillators by taking neuronal systems with nonlinear coupling function into account while such ensembles of oscillators are more realistic from a neurobiological point of view. In this paper, we report the emergence and existence of chimera states by considering locally coupled two-dimensional networks of identical oscillators where each node is interacting through nonlinear coupling function. This is in contrast with the existence of chimera states in two-dimensional nonlocally coupled oscillators with rectangular kernel in the coupling function. We find that the presence of nonlinearity in the coupling function plays a key role to produce chimera states in two-dimensional locally coupled oscillators. We analytically verify explicitly in the case of a network of coupled Stuart-Landau oscillators in two dimensions that the obtained results using Ott-Antonsen approach and our analytical finding very well matches with the numerical results. Next, we consider another type of important nonlinear coupling function which exists in neuronal systems, namely chemical synaptic function, through which the nearest-neighbor (locally coupled) neurons interact with each other. It is shown that such synaptic interacting function promotes the emergence of chimera states in two-dimensional lattices of locally coupled neuronal oscillators. In numerical simulations, we consider two paradigmatic neuronal oscillators, namely Hindmarsh-Rose neuron model and Rulkov map for each node which exhibit bursting dynamics. By associating various spatiotemporal behaviors and snapshots at particular times, we study the chimera

Tools for integrated sequence-structure analysis with UCSF Chimera

Directory of Open Access Journals (Sweden)

Huang Conrad C

2006-07-01

Full Text Available Abstract Background Comparing related structures and viewing the structures in the context of sequence alignments are important tasks in protein structure-function research. While many programs exist for individual aspects of such work, there is a need for interactive visualization tools that: (a provide a deep integration of sequence and structure, far beyond mapping where a sequence region falls in the structure and vice versa; (b facilitate changing data of one type based on the other (for example, using only sequence-conserved residues to match structures, or adjusting a sequence alignment based on spatial fit; (c can be used with a researcher's own data, including arbitrary sequence alignments and annotations, closely or distantly related sets of proteins, etc.; and (d interoperate with each other and with a full complement of molecular graphics features. We describe enhancements to UCSF Chimera to achieve these goals. Results The molecular graphics program UCSF Chimera includes a suite of tools for interactive analyses of sequences and structures. Structures automatically associate with sequences in imported alignments, allowing many kinds of crosstalk. A novel method is provided to superimpose structures in the absence of a pre-existing sequence alignment. The method uses both sequence and secondary structure, and can match even structures with very low sequence identity. Another tool constructs structure-based sequence alignments from superpositions of two or more proteins. Chimera is designed to be extensible, and mechanisms for incorporating user-specific data without Chimera code development are also provided. Conclusion The tools described here apply to many problems involving comparison and analysis of protein structures and their sequences. Chimera includes complete documentation and is intended for use by a wide range of scientists, not just those in the computational disciplines. UCSF Chimera is free for non-commercial use and is

Monoclonal antibodies against a synthetic peptide from human immunodeficiency virus type 1 Nef protein

DEFF Research Database (Denmark)

Steinaa, L; Wulff, A M; Saermark, T

1994-01-01

Monoclonal antibodies against a synthetic peptide (aa 138-152) from HIV-1 Nef protein were produced and characterized. Three hybridoma lines producing monoclonal antibodies (MAbs) against the synthetic peptide were generated by fusion between P3-X63 Ag8.653 myeloma cells and BALB/c splenocytes from...... mice immunized with the synthetic peptide coupled to keyhole limpet hemocyanin (KLH). The hybridomas were screened and selected by ELISA with the peptide coupled to bovine serum albumin (BSA) immobilized to the polystyrene surface and specificity for the peptide was confirmed by competitive ELISA...... with the peptide free in solution. The reactions of the MAbs with a 5-aa motif (WCYKL) included in the sequence were examined with synthetic peptides and two of the MAbs reacted with the motif. The recognitions of recombinant full-length Nef protein were also tested. One MAb reacted with the protein in both ELISA...

Development of cassava periclinal chimera may boost production.

Science.gov (United States)

Bomfim, N; Nassar, N M A

2014-02-10

Plant periclinal chimeras are genotypic mosaics arranged concentrically. Trials to produce them to combine different species have been done, but pratical results have not been achieved. We report for the second time the development of a very productive interspecific periclinal chimera in cassava. It has very large edible roots up to 14 kg per plant at one year old compared to 2-3 kg in common varieties. The epidermal tissue formed was from Manihot esculenta cultivar UnB 032, and the subepidermal and internal tissue from the wild species, Manihot fortalezensis. We determined the origin of tissues by meiotic and mitotic chromosome counts, plant anatomy and morphology. Epidermal features displayed useful traits to deduce tissue origin: cell shape and size, trichome density and stomatal length. Chimera roots had a wholly tuberous and edible constitution with smaller starch granule size and similar distribution compared to cassava. Root size enlargement might have been due to an epigenetic effect. These results suggest a new line of improved crop based on the development of interspecific chimeras composed of different combinations of wild and cultivated species. It promises boosting cassava production through exceptional root enlargement.

H-2 restriction of the T cell response to chemically induced tumors: evidence from F1 → parent chimeras

International Nuclear Information System (INIS)

Lannin, D.R.; Yu, S.; McKhann, C.F.

1982-01-01

It has been well established that T cells that react to tumor antigen on virus-induced tumors must share H-2D or H-2K specificities with the tumor. It has been impossible to perform similar studies with chemically induced tumors because each chemically induced tumor expresses a unique tumor antigen that cannot be studied in association with other H-2 types. This study provies evidence that H-2 recognition is also necessary for recognition of chemically induced tumors. We have found that F 1 → parent chimeras preferentially recognize chemically induced tumors of parental H-2 type. C3H/HeJ and C57BL/6 mice were lethally irradiated and restored with (C3H x C57BL/6) F 1 hybrid bone marrow. The F 1 → C3H chimera but not the F 1 → C57BL/6 chimera was able to respond to a C3H fibrosarcoma in mixed lymphocyte-tumor cell culture and also to neutralize the tumor in an in vivo tumor neutralization assay. On the other hand, the F 1 → C57BL/6 chimera but not the F 1 → C3H chimera was able to kill the C57BL/6 lymphoma EL4 in an in vitro cytotoxicity assay. Both chimeras were tolerant to C3H and C57BL/6 alloantigens but could respond normally to Con A and to BALB/c spleen cells in mixed lymphocyte cultures and cytotoxicity assay

Chaotic weak chimeras and their persistence in coupled populations of phase oscillators

International Nuclear Information System (INIS)

Bick, Christian; Ashwin, Peter

2016-01-01

Nontrivial collective behavior may emerge from the interactive dynamics of many oscillatory units. Chimera states are chaotic patterns of spatially localized coherent and incoherent oscillations. The recently-introduced notion of a weak chimera gives a rigorously testable characterization of chimera states for finite-dimensional phase oscillator networks. In this paper we give some persistence results for dynamically invariant sets under perturbations and apply them to coupled populations of phase oscillators with generalized coupling. In contrast to the weak chimeras with nonpositive maximal Lyapunov exponents constructed so far, we show that weak chimeras that are chaotic can exist in the limit of vanishing coupling between coupled populations of phase oscillators. We present numerical evidence that positive Lyapunov exponents can persist for a positive measure set of this inter-population coupling strength. (paper)

Recent results of CHIMERA activity

Directory of Open Access Journals (Sweden)

Pagano A.

2012-07-01

Full Text Available The experimental activity of CHIMERA in recent years has been characterized by a steady progress in the detection technique and data analysis. Since 2008 the detector system benefits of new implementations: a new reaction chamber, a new charged particle identification in silicon detector made by an extended pulse shape method and an efficient system for the identification of exotic beams produced by projectile-like fragmentation (In-flight method. These implementations appear to be promising tools in view of further exclusive experiments in the field of isospin physics. The coupling of CHIMERA with other equipments (such as interferometers and highly segmented arrays, magnetic elements, neutron detectors, etc. is also envisaged in order to extend the studies of the reaction mechanism in heavy ion physics.

Computing Flows Using Chimera and Unstructured Grids

Science.gov (United States)

Liou, Meng-Sing; Zheng, Yao

2006-01-01

DRAGONFLOW is a computer program that solves the Navier-Stokes equations of flows in complexly shaped three-dimensional regions discretized by use of a direct replacement of arbitrary grid overlapping by nonstructured (DRAGON) grid. A DRAGON grid (see figure) is a combination of a chimera grid (a composite of structured subgrids) and a collection of unstructured subgrids. DRAGONFLOW incorporates modified versions of two prior Navier-Stokes-equation-solving programs: OVERFLOW, which is designed to solve on chimera grids; and USM3D, which is used to solve on unstructured grids. A master module controls the invocation of individual modules in the libraries. At each time step of a simulated flow, DRAGONFLOW is invoked on the chimera portion of the DRAGON grid in alternation with USM3D, which is invoked on the unstructured subgrids of the DRAGON grid. The USM3D and OVERFLOW modules then immediately exchange their solutions and other data. As a result, USM3D and OVERFLOW are coupled seamlessly.

Pulse shape method for the Chimera silicon detectors

Energy Technology Data Exchange (ETDEWEB)

Pagano, A.; Arena, N.; Cardella, G.; D' Andrea, M.; Filippo, E. de; Fichera, F.; Giudice, N.; Guardone, N.; Grimaldi, A.; Nicotra, D.; Papa, M.; Pirrone, S.; Politi, G.; Rapicavoli, C.; Rizza, G.; Russotto, P.; Sacca, G.; Urso, S.; Lanzano, G. [Catania Univ., INFN Catania and Dipartimento di Fisica e Astronomia (Italy); Alderighi, M.; Sechi, G. [INFN Milano and Istituto di Fisica Cosmica CNR, Milano (Italy); Amorini, F.; Anzalone, A.; Cali, C.; Campagna, V.; Cavallaro, S.; Di Stefano, A.; Giustolisi, F.; La Guidara, E.; Lanzalone, G.; Maiolino, C.; Porto, F.; Rizzo, F.; Salamone, S. [Catania Univ., INFN-LNS and Dipartimento di Fisica e Astronomia (Italy); Auditore, L.; Trifiro, A.; Trimarchi, M. [Messina Univ., INFN and Dipartimento di Fisica (Italy); Bassini, R.; Boiano, C.; Guazzoni, P.; Russo, S.; Sassi, M.; Zetta, L. [Milano Univ., INFN Milano and Dipartimento di Fisica (Italy); Blicharska, J.; Grzeszczuk, A. [Silesia Univ., Institute of Physics, Katowice (Poland); Chatterjee, M.B. [Saha Institute Of Nuclear Physics, Kolkata (India); Geraci, E.; Zipper, W. [Bologna Univ., INFN Bologna and Dipartimento di Fisica (Italy); Rosato, E.; Vigilante, M. [Napoli Univ., INFN and Dipartimento di Fisica (Italy); Schroder, W.U.; T-ke, J. [Rochester Univ., Dept. of Chemistry, Rochester, N.Y. (United States)

2003-07-01

Since January 2003, the 4{pi} CHIMERA (Charged Heavy Ions Mass and Energy Resolving Array) detector in its full configuration has successfully been operated at the 'Catania Laboratori Nazionali del Sud' (LNS) accelerator facility. The detector has been used with a variety of beams from the Superconducting Cyclotron in heavy-ion reaction studies at Fermi bombarding energies. Future experiments with a focus on isospin physics at Fermi energies, planned for both primary and less intense secondary particle beams, suggest the development of new and more versatile experimental particle identification methods. Recent achievements in implementing specific pulse shape particle identification methods for CHIMERA silicon detectors are reported. They suggest an upgrade of the present charge and mass identification capability of CHIMERA by a simple extension of the method. (authors)

Targeted chimera delivery to ovarian cancer cells by heterogeneous gold magnetic nanoparticle

Science.gov (United States)

Chen, Yao; Xu, Mengjiao; Guo, Yi; Tu, Keyao; Wu, Weimin; Wang, Jianjun; Tong, Xiaowen; Wu, Wenjuan; Qi, Lifeng; Shi, Donglu

2017-01-01

Efficient delivery of small interfering RNAs (siRNAs) to the targeted cells has remained a significant challenge in clinical applications. In the present study, we developed a novel aptamer-siRNA chimera delivery system mediated by cationic Au-Fe3O4 nanoparticles (NPs). The chimera constructed by VEGF RNA aptamer and Notch3 siRNA was bonded with heterogeneous Au-Fe3O4 nanoparticles by electrostatic interaction. The obtained complex exhibited much higher silencing efficiency against Notch3 gene compared with chimera alone and lipofectamine-siRNA complex, and improved the antitumor effects of the loaded chimera. Moreover, the efficient delivery of the chimera by Au-Fe3O4 NPs could reverse multi-drug resistance (MDR) of ovarian cancer cells against the chemotherapeutic drug cisplatin, indicating its potential capability for future targeted cancer therapy while overcoming MDR.

Remodeling of the Host Cell Plasma Membrane by HIV-1 Nef and Vpu: A Strategy to Ensure Viral Fitness and Persistence.

Science.gov (United States)

Sugden, Scott M; Bego, Mariana G; Pham, Tram N Q; Cohen, Éric A

2016-03-03

The plasma membrane protects the cell from its surroundings and regulates cellular communication, homing, and metabolism. Not surprisingly, the composition of this membrane is highly controlled through the vesicular trafficking of proteins to and from the cell surface. As intracellular pathogens, most viruses exploit the host plasma membrane to promote viral replication while avoiding immune detection. This is particularly true for the enveloped human immunodeficiency virus (HIV), which assembles and obtains its lipid shell directly at the plasma membrane. HIV-1 encodes two proteins, negative factor (Nef) and viral protein U (Vpu), which function primarily by altering the quantity and localization of cell surface molecules to increase virus fitness despite host antiviral immune responses. These proteins are expressed at different stages in the HIV-1 life cycle and employ a variety of mechanisms to target both unique and redundant surface proteins, including the viral receptor CD4, host restriction factors, immunoreceptors, homing molecules, tetraspanins and membrane transporters. In this review, we discuss recent progress in the study of the Nef and Vpu targeting of host membrane proteins with an emphasis on how remodeling of the cell membrane allows HIV-1 to avoid host antiviral immune responses leading to the establishment of systemic and persistent infection.

Chimera: Experiencing Language Arts.

Science.gov (United States)

Paul, Rebecca K.

1991-01-01

Describes the production of a dramatic musical, Chimera: A Journey to Redoubtia, at Chapman Elementary School in Anchor Point, Alaska. Student participation in the project, and students' rewards from participation, are detailed. Benefits of the integration of dramatics into the language arts curriculum are listed. (BB)

Using quantitative real-time PCR to detect chimeras in transgenic tobacco and apricot and to monitor their dissociation

Directory of Open Access Journals (Sweden)

Burgos Lorenzo

2010-07-01

Full Text Available Abstract Background The routine generation of transgenic plants involves analysis of transgene integration into the host genome by means of Southern blotting. However, this technique cannot distinguish between uniformly transformed tissues and the presence of a mixture of transgenic and non-transgenic cells in the same tissue. On the other hand, the use of reporter genes often fails to accurately detect chimerical tissues because their expression can be affected by several factors, including gene silencing and plant development. So, new approaches based on the quantification of the amount of the transgene are needed urgently. Results We show here that chimeras are a very frequent phenomenon observed after regenerating transgenic plants. Spatial and temporal analyses of transformed tobacco and apricot plants with a quantitative, real-time PCR amplification of the neomycin phosphotransferase (nptII transgene as well as of an internal control (β-actin, used to normalise the amount of target DNA at each reaction, allowed detection of chimeras at unexpected rates. The amount of the nptII transgene differed greatly along with the sub-cultivation period of these plants and was dependent on the localisation of the analysed leaves; being higher in roots and basal leaves, while in the apical leaves it remained at lower levels. These data demonstrate that, unlike the use of the gus marker gene, real-time PCR is a powerful tool for detection of chimeras. Although some authors have proposed a consistent, positive Southern analysis as an alternative methodology for monitoring the dissociation of chimeras, our data show that it does not provide enough proof of uniform transformation. In this work, however, real-time PCR was applied successfully to monitor the dissociation of chimeras in tobacco plants and apricot callus. Conclusions We have developed a rapid and reliable method to detect and estimate the level of chimeras in transgenic tobacco and apricot

Mechanisms of tolerance in murine radiation bone marrow chimeras. II. Absence of nonspecific suppression in mature chimeras

International Nuclear Information System (INIS)

Auchincloss, H. Jr.; Sachs, D.H.

1983-01-01

Spleen cells from a series of allogeneic bone marrow chimeras were sensitized in vitro with stimulator cells from major histocompatibility complex recombinant strains of mice. The combinations were chosen such that both tolerated (host or donor) and nontolerated (third-party) antigens were present on the same stimulator cells in order to determine whether the tolerated host antigens might elicit nonspecific suppressor mechanisms affecting the cell-mediated lympholysis (CML) response to the nontolerated antigens. No evidence for such nonspecific suppression was obtained in several types of assays. Therefore, if suppressor mechanisms exist that mediate such tolerance in mature allogeneic chimeras then these mechanisms must be highly antigen-specific

Chimera-like states in structured heterogeneous networks

Science.gov (United States)

Li, Bo; Saad, David

2017-04-01

Chimera-like states are manifested through the coexistence of synchronous and asynchronous dynamics and have been observed in various systems. To analyze the role of network topology in giving rise to chimera-like states, we study a heterogeneous network model comprising two groups of nodes, of high and low degrees of connectivity. The architecture facilitates the analysis of the system, which separates into a densely connected coherent group of nodes, perturbed by their sparsely connected drifting neighbors. It describes a synchronous behavior of the densely connected group and scaling properties of the induced perturbations.

Bone marrow cells from allogeneic bone marrow chimeras inhibit the generation of cytotoxic lymphocyte responses against both donor and recipient cells

International Nuclear Information System (INIS)

Ogasawara, M.; Iwabuchi, K.; Good, R.A.; Onoe, K.

1988-01-01

When added to a mixed lymphocyte culture, bone marrow cells suppress the generation of CTL activity against H-2 Ag shared by the BM cells and the stimulator cells. These cells have been referred to as veto cells and are thought to play a role in maintaining self-tolerance. We analyzed the H-2 specificity of the suppression expressed by the veto cells from H-2 incompatible bone marrow chimeras, because lymphocytes of such chimeras had been shown to be tolerant to both donor and recipient Ag when tested by CTL responses. We found that the bone marrow cells of such chimeras which were featured by non-T and non-B cell characteristics inhibited the generation of CTL directed against either donor or recipient Ag, but not against third-party Ag. These observations suggest that in allogeneic chimeras the veto or veto-like cells alter the inhibitory specificity exhibited in the recipient microenvironment and indicate that these cells are directly involved in the induction and maintenance of self-tolerance

Construction and characterization of the interdomain chimeras using Cry11Aa and Cry11Ba from Bacillus thuringiensis and identification of a possible novel toxic chimera.

Science.gov (United States)

Sun, Yunjun; Zhao, Qiang; Zheng, Dasheng; Ding, Xuezhi; Wang, Jingfang; Hu, Quanfang; Yuan, Zhiming; Park, Hyun-Woo; Xia, Liqiu

2014-01-01

Three structural domains of mosquitocidal Cry11Aa and Cry11Ba from Bacillus thuringiensis were exchanged to produce interdomain chimeras [BAA (11Ba/11Aa/11Aa), ABA (11Aa/11Ba/11Aa), AAB (11Aa/11Aa/11Ba), ABB (11Aa/11Ba/11Ba), BAB (11Ba/11Aa/11Ba), BBA (11Ba/11Ba/11Aa]. Chimeras BAB, BAA, BBA, and AAB formed inclusion bodies in the crystal-negative B. thuringiensis host and produced expected protein bands on SDS-PAGE gel. However, no inclusion body or target protein could be found for chimeras ABA and ABB. In bioassays using the fourth-instar larvae of Culex quinquefasciatus and Aedes aegypti, AAB had ~50 % lethal concentrations of 4.8 and 2.2 μg ml(-1), respectively; however, the rest of chimeras were not toxic. This study thus helps to understand the domain-function relationships of the Cry11Aa and Cry11Ba toxins. The toxic chimera, AAB, might be a candidate for mosquito control as its amino acid sequence is different from the two parental toxins.

MODELS FOR MOUSE CHIMERA PRODUCTION: AGGREGATION OF ES CELLS WITH CLEAVAGE STAGE EMBRYOS

Directory of Open Access Journals (Sweden)

STANCA CLAUDIA

2007-01-01

Full Text Available In a mutant ES cells↔ wild-type embryo chimera, ES cells behave more like epiblastcells. They can contribute to the primitive ectoderm layers, which give rise to all theembryonic tissues and some extraembryonic tissues (Beddington and Robertson,1989, but not to trophectoderm or primitive endoderm. Using transgenic ES celllines, aggregated with cleavage stage host embryo, ES cells can integrate randomlyin the embryo proper. If they will be take part in the formation of ICM (inner cellmass, it will be possible to obtain germline chimera animals. To generate ES cells↔ cleavage stage host embryo chimeras, we used (CD-1 mice as donors of hostembryos as well as recipients of manipulated embryos. For chimera production, weused fluorescent-labeled ES cell line (CD1/EGFP, because in this case we canfollow the fate of ES cells during the embryonic development. We produced thechimers using “aggregation chimera technique”. 8 cells stage zona pellucida free,mouse embryos were aggregated in an aggregation plates, with a clump of ES cells(10 – 15 cells. The chimera embryos were cultivated for 24 hours in the incubator(at 37 °C, 5% CO2 in air. The chimera blastocysts resulted after cultivation, weretransferred to the uterus of the 2.5-dpc pseudo pregnant females.

MODELS FOR MOUSE CHIMERA PRODUCTION: AGGREGATION OF ES CELLS WITH CLEAVAGE STAGE EMBRYOS

Directory of Open Access Journals (Sweden)

CLAUDIA STANCA

2007-05-01

Full Text Available In a mutant ES cells↔ wild-type embryo chimera, ES cells behave more like epiblastcells. They can contribute to the primitive ectoderm layers, which give rise to all theembryonic tissues and some extraembryonic tissues (Beddington and Robertson,1989, but not to trophectoderm or primitive endoderm. Using transgenic ES celllines, aggregated with cleavage stage host embryo, ES cells can integrate randomlyin the embryo proper. If they will be take part in the formation of ICM (inner cellmass, it will be possible to obtain germline chimera animals. To generate ES cells↔ cleavage stage host embryo chimeras, we used (CD-1 mice as donors of hostembryos as well as recipients of manipulated embryos. For chimera production, weused fluorescent-labeled ES cell line (CD1/EGFP, because in this case we canfollow the fate of ES cells during the embryonic development. We produced thechimers using “aggregation chimera technique”. 8 cells stage zona pellucida free,mouse embryos were aggregated in an aggregation plates, with a clump of ES cells(10 – 15 cells. The chimera embryos were cultivated for 24 hours in the incubator(at 37 °C, 5% CO2 in air. The chimera blastocysts resulted after cultivation, weretransferred to the uterus of the 2.5-dpc pseudo pregnant females.

Chimera states in a population of identical oscillators under planar ...

Indian Academy of Sciences (India)

finding, observed in both a collection of van der Pol oscillators and chaotic Rössler oscillators, fur- ther simplifies the existence criterion for chimeras, thereby broadens the range of their applicability to real-world situations. Keywords. Synchronization; chimera; Rössler system; van der Pol oscillator. PACS Nos 05.45.

Chimera States in Continuous Media: Existence and Distinctness

Science.gov (United States)

Nicolaou, Zachary G.; Riecke, Hermann; Motter, Adilson E.

2017-12-01

The defining property of chimera states is the coexistence of coherent and incoherent domains in systems that are structurally and spatially homogeneous. The recent realization that such states might be common in oscillator networks raises the question of whether an analogous phenomenon can occur in continuous media. Here, we show that chimera states can exist in continuous systems even when the coupling is strictly local, as in many fluid and pattern forming media. Using the complex Ginzburg-Landau equation as a model system, we characterize chimera states consisting of a coherent domain of a frozen spiral structure and an incoherent domain of amplitude turbulence. We show that in this case, in contrast with discrete network systems, fluctuations in the local coupling field play a crucial role in limiting the coherent regions. We suggest these findings shed light on new possible forms of coexisting order and disorder in fluid systems.

Interspecific in vitro assay for the chimera-forming ability of human pluripotent stem cells.

Science.gov (United States)

Masaki, Hideki; Kato-Itoh, Megumi; Umino, Ayumi; Sato, Hideyuki; Hamanaka, Sanae; Kobayashi, Toshihiro; Yamaguchi, Tomoyuki; Nishimura, Ken; Ohtaka, Manami; Nakanishi, Mahito; Nakauchi, Hiromitsu

2015-09-15

Functional assay limitations are an emerging issue in characterizing human pluripotent stem cells (PSCs). With rodent PSCs, chimera formation using pre-implantation embryos is the gold-standard assay of pluripotency (competence of progeny to differentiate into all three germ layers). In human PSCs (hPSCs), however, this can only be monitored via teratoma formation or in vitro differentiation, as ethical concerns preclude generation of human-human or human-animal chimeras. To circumvent this issue, we developed a functional assay utilizing interspecific blastocyst injection and in vitro culture (interspecies in vitro chimera assay) that enables the development and observation of embryos up to headfold stage. The assay uses mouse pre-implantation embryos and rat, monkey and human PSCs to create interspecies chimeras cultured in vitro to the early egg-cylinder stage. Intra- and interspecific chimera assays with rodent PSC lines were performed to confirm the consistency of results in vitro and in vivo. The behavior of chimeras developed in vitro appeared to recapitulate that of chimeras developed in vivo; that is, PSC-derived cells survived and were integrated into the epiblast of egg-cylinder-stage embryos. This indicates that the interspecific in vitro chimera assay is useful in evaluating the chimera-forming ability of rodent PSCs. However, when human induced PSCs (both conventional and naïve-like types) were injected into mouse embryos and cultured, some human cells survived but were segregated; unlike epiblast-stage rodent PSCs, they never integrated into the epiblast of egg-cylinder-stage embryos. These data suggest that the mouse-human interspecies in vitro chimera assay does not accurately reflect the early developmental potential/process of hPSCs. The use of evolutionarily more closely related species as host embryos might be necessary to evaluate the developmental potency of hPSCs. © 2015. Published by The Company of Biologists Ltd.

Experimental observation of chimera and cluster states in a minimal globally coupled network

Energy Technology Data Exchange (ETDEWEB)

Hart, Joseph D. [Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland 20742 (United States); Department of Physics, University of Maryland, College Park, Maryland 20742 (United States); Bansal, Kanika [Department of Mathematics, University at Buffalo, SUNY Buffalo, New York 14260 (United States); US Army Research Laboratory, Aberdeen Proving Ground, Maryland 21005 (United States); Murphy, Thomas E. [Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland 20742 (United States); Department of Electrical and Computer Engineering, University of Maryland, College Park, Maryland 20742 (United States); Roy, Rajarshi [Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland 20742 (United States); Department of Physics, University of Maryland, College Park, Maryland 20742 (United States); Institute for Physical Science and Technology, University of Maryland, College Park, Maryland 20742 (United States)

2016-09-15

A “chimera state” is a dynamical pattern that occurs in a network of coupled identical oscillators when the symmetry of the oscillator population is broken into synchronous and asynchronous parts. We report the experimental observation of chimera and cluster states in a network of four globally coupled chaotic opto-electronic oscillators. This is the minimal network that can support chimera states, and our study provides new insight into the fundamental mechanisms underlying their formation. We use a unified approach to determine the stability of all the observed partially synchronous patterns, highlighting the close relationship between chimera and cluster states as belonging to the broader phenomenon of partial synchronization. Our approach is general in terms of network size and connectivity. We also find that chimera states often appear in regions of multistability between global, cluster, and desynchronized states.

Fatty acids activate a chimera of the clofibric acid-activated receptor and the glucocorticoid receptor.

Science.gov (United States)

Göttlicher, M; Widmark, E; Li, Q; Gustafsson, J A

1992-01-01

Peroxisome proliferators such as clofibric acid, nafenopin, and WY-14,643 have been shown to activate PPAR (peroxisome proliferator-activated receptor), a member of the steroid nuclear receptor superfamily. We have cloned the cDNA from the rat that is homologous to that from the mouse [Issemann, I. & Green, S. (1990) Nature (London) 347, 645-650], which encodes a 97% similar protein with a particularly well-conserved putative ligand-binding domain. To search for physiologically occurring activators, we established a transcriptional transactivation assay by stably expressing in CHO cells a chimera of rat PPAR and the human glucocorticoid receptor that activates expression of the placental alkaline phosphatase reporter gene under the control of the mouse mammary tumor virus promoter. Testing of compounds related to lipid metabolism or peroxisomal proliferation revealed that 150 microM concentrations of arachidonic or linoleic acid but not of dehydroepiandrosterone, cholesterol, or 25-hydroxy-cholesterol, activate the receptor chimera. In addition, saturated fatty acids induce the reporter gene. Shortening the chain length to n = 6 or introduction of an omega-terminal carboxylic group abolished the activation potential of the fatty acid. In conclusion, the present results indicate that fatty acids can regulate gene expression mediated by a member of the steroid nuclear receptor superfamily. Images PMID:1316614

Radiobiological research on carnation chimerae Dianthus Caryophyllus L

International Nuclear Information System (INIS)

Pereau-Leroy, Pierre.

1975-01-01

A radiobiological study of periclinal carnation chimerae is carried out by subjecting whole plants and cuttings at different physiological stages to cobalt 60 gamma radiation under different dose and dose rate conditions. The effects of these treatments are observed during cultivation of the treated plants and by microscopic examination of irradiated meristem sections. The destruction of meristem cells in proportions varying with the irradiation conditions leads to structural changes in the chimerae; the more frequent change is the formation of genetically homogeneous stalks from different genotypes existing in the irradiated plant. Treatment by ionizing radiations is thus a practical means of detecting periclinical chimerae which, as in the case of carnations, are very common in plants grown by vegetative propagation. However since more than two independent meristem cell groups are usually present it is not possible by this method alone to define the distribution of the differentent genotypes in these groups; additional genetic studies or cell labelling such as chlorophyll or genoma mutations are then necessary [fr

Mechanism of chimera formation during the Multiple Displacement Amplification reaction

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Stockwell Timothy B

2007-04-01

Full Text Available Abstract Background Multiple Displacement Amplification (MDA is a method used for amplifying limiting DNA sources. The high molecular weight amplified DNA is ideal for DNA library construction. While this has enabled genomic sequencing from one or a few cells of unculturable microorganisms, the process is complicated by the tendency of MDA to generate chimeric DNA rearrangements in the amplified DNA. Determining the source of the DNA rearrangements would be an important step towards reducing or eliminating them. Results Here, we characterize the major types of chimeras formed by carrying out an MDA whole genome amplification from a single E. coli cell and sequencing by the 454 Life Sciences method. Analysis of 475 chimeras revealed the predominant reaction mechanisms that create the DNA rearrangements. The highly branched DNA synthesized in MDA can assume many alternative secondary structures. DNA strands extended on an initial template can be displaced becoming available to prime on a second template creating the chimeras. Evidence supports a model in which branch migration can displace 3'-ends freeing them to prime on the new templates. More than 85% of the resulting DNA rearrangements were inverted sequences with intervening deletions that the model predicts. Intramolecular rearrangements were favored, with displaced 3'-ends reannealing to single stranded 5'-strands contained within the same branched DNA molecule. In over 70% of the chimeric junctions, the 3' termini had initiated priming at complimentary sequences of 2–21 nucleotides (nts in the new templates. Conclusion Formation of chimeras is an important limitation to the MDA method, particularly for whole genome sequencing. Identification of the mechanism for chimera formation provides new insight into the MDA reaction and suggests methods to reduce chimeras. The 454 sequencing approach used here will provide a rapid method to assess the utility of reaction modifications.

La priorale Saint-Pierre de Souvigny (Allier : étude archéologique de la nef, seconde tranche

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Sébastien Bully

2008-07-01

Full Text Available Comme en 2006, l’opération archéologique a été menée dans le cadre de la réfection intérieure des cinq vaisseaux de la nef de la priorale clunisienne par la CRMH d’Auvergne . L’intervention de quatre mois, toujours motivée par les risques de destruction générés par les travaux, avait pour objectif minimal de dégager, sur 30 à 35 cm de profondeur, le vaisseau central et les deux collatéraux sud de la nef ; soumise au calendrier du chantier, elle a débuté en avril, s’est poursuivie en juin et j...

Integration of the GET electronics for the CHIMERA and FARCOS devices

Science.gov (United States)

De Filippo, E.; Acosta, L.; Auditore, L.; Boiano, C.; Cardella, G.; Castoldi, A.; D’Andrea, M.; De Luca, S.; Favela, F.; Fichera, F.; Giudice, N.; Gnoffo, B.; Grimaldi, A.; Guazzoni, C.; Lanzalone, G.; Librizzi, F.; Litrico, P.; Maiolino, C.; Maffesanti, S.; Martorana, NS; Pagano, A.; Pagano, EV; Papa, M.; Parsani, T.; Passaro, G.; Pirrone, S.; Politi, G.; Previdi, F.; Quattrocchi, L.; Rizzo, F.; Russotto, P.; Saccà, G.; Salemi, G.; Sciliberto, D.; Trifirò, A.; Trimarchi, M.

2018-05-01

A new front-end based on digital GET electronics has been adopted for the readout of the CsI(Tl) detectors of the CHIMERA 4π multi-detector and for the new modular Femtoscopy Array for Correlation and Spectroscopy (FARCOS). It is expected that the coupling of CHIMERA with the FARCOS array, featuring high angular and energy resolution, and the adoption of the new digital electronics will be well suited for improving specific future data analysis, with the full shape storage of the signals, in the field of heavy ion reactions with stable and exotic beams around the Fermi energies domain. Integration of the GET electronics with CHIMERA and FARCOS devices and with the local analog data acquisition will be briefly discussed. We present some results from previous experimental tests and from the first in-beam experiment (Hoyle-Gamma) with the coupled GET+CHIMERA data acquisition.

Chimera-like states in a neuronal network model of the cat brain

Science.gov (United States)

Santos, M. S.; Szezech, J. D.; Borges, F. S.; Iarosz, K. C.; Caldas, I. L.; Batista, A. M.; Viana, R. L.; Kurths, J.

2017-08-01

Neuronal systems have been modeled by complex networks in different description levels. Recently, it has been verified that networks can simultaneously exhibit one coherent and other incoherent domain, known as chimera states. In this work, we study the existence of chimera states in a network considering the connectivity matrix based on the cat cerebral cortex. The cerebral cortex of the cat can be separated in 65 cortical areas organised into the four cognitive regions: visual, auditory, somatosensory-motor and frontolimbic. We consider a network where the local dynamics is given by the Hindmarsh-Rose model. The Hindmarsh-Rose equations are a well known model of neuronal activity that has been considered to simulate membrane potential in neuron. Here, we analyse under which conditions chimera states are present, as well as the affects induced by intensity of coupling on them. We observe the existence of chimera states in that incoherent structure can be composed of desynchronised spikes or desynchronised bursts. Moreover, we find that chimera states with desynchronised bursts are more robust to neuronal noise than with desynchronised spikes.

HIV-1 Nef in Macrophage-Mediated Disease Pathogenesis

Science.gov (United States)

Lamers, Susanna L.; Fogel, Gary B.; Singer, Elyse J.; Salemi, Marco; Nolan, David J.; Huysentruyt, Leanne C.; McGrath, Michael S.

2013-01-01

Combined anti-retroviral therapy (cART) has significantly reduced the number of AIDS-associated illnesses and changed the course of HIV-1 disease in developed countries. Despite the ability of cART to maintain high CD4+ T-cell counts, a number of macrophage-mediated diseases can still occur in HIV-infected subjects. These diseases include lymphoma, metabolic diseases, and HIV-associated neurological disorders. Within macrophages, the HIV-1 regulatory protein “Nef” can modulate surface receptors, interact with signaling pathways, and promote specific environments that contribute to each of these pathologies. Moreover, genetic variation in Nef may also guide the macrophage response. Herein, we review findings relating to the Nef–macrophage interaction and how this relationship contributes to disease pathogenesis. PMID:23215766

Chimera states in complex networks: interplay of fractal topology and delay

Science.gov (United States)

Sawicki, Jakub; Omelchenko, Iryna; Zakharova, Anna; Schöll, Eckehard

2017-06-01

Chimera states are an example of intriguing partial synchronization patterns emerging in networks of identical oscillators. They consist of spatially coexisting domains of coherent (synchronized) and incoherent (desynchronized) dynamics. We analyze chimera states in networks of Van der Pol oscillators with hierarchical connectivities, and elaborate the role of time delay introduced in the coupling term. In the parameter plane of coupling strength and delay time we find tongue-like regions of existence of chimera states alternating with regions of existence of coherent travelling waves. We demonstrate that by varying the time delay one can deliberately stabilize desired spatio-temporal patterns in the system.

A Universal Aptamer Chimera for the Delivery of Functional microRNA-126.

Science.gov (United States)

Rohde, Jan-H; Weigand, Julia E; Suess, Beatrix; Dimmeler, Stefanie

2015-06-01

microRNAs (miRs) regulate vascular diseases such as atherosclerosis and cancer. miR-126 is important for endothelial cell signaling and promotes angiogenesis, protects against atherosclerosis, and reduces breast cancer cell growth and metastasis. The overexpression of miR-126, therefore, may be an attractive therapeutic strategy for the treatment of cardiovascular disease or cancer. Here we report a novel strategy to deliver miR-126 to endothelial and breast cancer cells. We tested three different strategies to deliver miR-126 by linking the miR to an aptamer for the ubiquitously expressed transferrin receptor (transferrin receptor aptamer, TRA). Linking the precursor of miR-126 (pre-miR-126) to the TRA by annealing of a complementary stick led to efficient uptake and processing of miR-126, resulting in the delivery of 1.6×10(6)±0.3×10(6) copies miR-126-3p per ng RNA in human endothelial cells and 7.4×10(5)±2×10(5) copies miR-126-3p per ng in MCF7 breast cancer cells. The functionality of the active TRA-miR-126 chimera was further demonstrated by showing that the chimera represses the known miR-126 target VCAM-1 and improved endothelial cell sprouting in a spheroid assay. Moreover, the TRA-miR-126 chimera reduced proliferation and paracrine endothelial cell recruitment of breast cancer cells to a similar extent as miR-126-3p mimics introduced by conventional liposome-based transfection. Together, this data demonstrates that pre-miR-126 can be delivered by a non-specific aptamer to exert biological functions in two different cell models. The use of the TRA-miR-126 chimera or the combination of the delivery strategy with other endothelial or tumor specific aptamers may provide an interesting therapeutic option to treat vascular disease or cancers.

Persistent Low-Level Replication of SIVΔnef Drives Maturation of Antibody and CD8 T Cell Responses to Induce Protective Immunity against Vaginal SIV Infection.

Science.gov (United States)

Adnan, Sama; Reeves, R Keith; Gillis, Jacqueline; Wong, Fay E; Yu, Yi; Camp, Jeremy V; Li, Qingsheng; Connole, Michelle; Li, Yuan; Piatak, Michael; Lifson, Jeffrey D; Li, Wenjun; Keele, Brandon F; Kozlowski, Pamela A; Desrosiers, Ronald C; Haase, Ashley T; Johnson, R Paul

2016-12-01

Defining the correlates of immune protection conferred by SIVΔnef, the most effective vaccine against SIV challenge, could enable the design of a protective vaccine against HIV infection. Here we provide a comprehensive assessment of immune responses that protect against SIV infection through detailed analyses of cellular and humoral immune responses in the blood and tissues of rhesus macaques vaccinated with SIVΔnef and then vaginally challenged with wild-type SIV. Despite the presence of robust cellular immune responses, animals at 5 weeks after vaccination displayed only transient viral suppression of challenge virus, whereas all macaques challenged at weeks 20 and 40 post-SIVΔnef vaccination were protected, as defined by either apparent sterile protection or significant suppression of viremia in infected animals. Multiple parameters of CD8 T cell function temporally correlated with maturation of protection, including polyfunctionality, phenotypic differentiation, and redistribution to gut and lymphoid tissues. Importantly, we also demonstrate the induction of a tissue-resident memory population of SIV-specific CD8 T cells in the vaginal mucosa, which was dependent on ongoing low-level antigenic stimulation. Moreover, we show that vaginal and serum antibody titers inversely correlated with post-challenge peak viral load, and we correlate the accumulation and affinity maturation of the antibody response to the duration of the vaccination period as well as to the SIVΔnef antigenic load. In conclusion, maturation of SIVΔnef-induced CD8 T cell and antibody responses, both propelled by viral persistence in the gut mucosa and secondary lymphoid tissues, results in protective immune responses that are able to interrupt viral transmission at mucosal portals of entry as well as potential sites of viral dissemination.

Pharmacological characterisation of α6β4* nicotinic acetylcholine receptors assembled from three different α6/α3 subunit chimeras in tsA201 cells

DEFF Research Database (Denmark)

Jensen, Anne Bjørnskov; Hoestgaard-Jensen, Kirsten; Jensen, Anders A.

2014-01-01

by their inefficient functional expression in vitro. In the present study we have characterized and compared the pharmacological properties displayed by α6β4 and α6β4β3 nicotinic acetylcholine receptors assembled in tsA201 cells from the classical α6/α3 chimera (C1) and two novel α6/α3 chimeras (C6F223L and C16F223L...... should be made keeping the molecular modifications in the α6 surrogate subunits in mind, this study sheds light on the pharmacological properties of α6β4⁎ nicotinic acetylcholine receptors and demonstrates the applicability of the C6F223L and C16F223L chimeras for studies of these receptors....

Chimera states in a multilayer network of coupled and uncoupled neurons

Science.gov (United States)

Majhi, Soumen; Perc, Matjaž; Ghosh, Dibakar

2017-07-01

We study the emergence of chimera states in a multilayer neuronal network, where one layer is composed of coupled and the other layer of uncoupled neurons. Through the multilayer structure, the layer with coupled neurons acts as the medium by means of which neurons in the uncoupled layer share information in spite of the absence of physical connections among them. Neurons in the coupled layer are connected with electrical synapses, while across the two layers, neurons are connected through chemical synapses. In both layers, the dynamics of each neuron is described by the Hindmarsh-Rose square wave bursting dynamics. We show that the presence of two different types of connecting synapses within and between the two layers, together with the multilayer network structure, plays a key role in the emergence of between-layer synchronous chimera states and patterns of synchronous clusters. In particular, we find that these chimera states can emerge in the coupled layer regardless of the range of electrical synapses. Even in all-to-all and nearest-neighbor coupling within the coupled layer, we observe qualitatively identical between-layer chimera states. Moreover, we show that the role of information transmission delay between the two layers must not be neglected, and we obtain precise parameter bounds at which chimera states can be observed. The expansion of the chimera region and annihilation of cluster and fully coherent states in the parameter plane for increasing values of inter-layer chemical synaptic time delay are illustrated using effective range measurements. These results are discussed in the light of neuronal evolution, where the coexistence of coherent and incoherent dynamics during the developmental stage is particularly likely.

Viremic long-term nonprogressive HIV-1 infection is not associated with abnormalities in known Nef functions

NARCIS (Netherlands)

Heigele, Anke; Camerini, David; van't Wout, Angélique B.; Kirchhoff, Frank

2014-01-01

A small minority of HIV-1-infected individuals show low levels of immune activation and do not develop immunodeficiency despite high viral loads. Since the accessory viral Nef protein modulates T cell activation and plays a key role in the pathogenesis of AIDS, we investigated whether specific

Chimeras in a network of three oscillator populations with varying network topology

DEFF Research Database (Denmark)

Martens, Erik Andreas

2010-01-01

this system as a model system, we discuss for the first time the influence of network topology on the existence of so-called chimera states. In this context, the network with three populations represents an interesting case because the populations may either be connected as a triangle, or as a chain, thereby......-like. By showing that chimera states only exist for a bounded set of parameter values, we demonstrate that their existence depends strongly on the underlying network structures, and conclude that chimeras exist on networks with a chain-like character....

Robust Weak Chimeras in Oscillator Networks with Delayed Linear and Quadratic Interactions

Science.gov (United States)

Bick, Christian; Sebek, Michael; Kiss, István Z.

2017-10-01

We present an approach to generate chimera dynamics (localized frequency synchrony) in oscillator networks with two populations of (at least) two elements using a general method based on a delayed interaction with linear and quadratic terms. The coupling design yields robust chimeras through a phase-model-based design of the delay and the ratio of linear and quadratic components of the interactions. We demonstrate the method in the Brusselator model and experiments with electrochemical oscillators. The technique opens the way to directly bridge chimera dynamics in phase models and real-world oscillator networks.

Availability of endogenous peptides limits expression of an M3a-Ld major histocompatibility complex class I chimera

Science.gov (United States)

1994-01-01

Taking advantage of our understanding of the peptide specificity of the major histocompatibility complex class I-b molecule M3a, we sought to determine why these molecules are poorly represented on the cell surface. To this end we constructed a chimeric molecule with the alpha 1 and alpha 2 domains of M3a and alpha 3 of Ld thereby allowing use of available monoclonal antibodies to quantify surface expression. Transfected, but not control, B10.CAS2 (H-2M3b) cells were lysed readily by M3a-restricted monoclonal cytotoxic T lymphocytes. Thus, the chimera bound, trafficked, and presented endogenous mitochondrial peptides. However, despite high levels of M3a-Ld mRNA, transfectants were negative by surface staining. This finding was consistent with inefficient trafficking to the cell surface. Incubation at 26 degrees C, thought to permit trafficking of unoccupied heavy (H) chains, resulted in detectable cell surface expression of chimeric molecules. Incubation with exogenous peptide at 26 degrees C (but not at 37 degrees C) greatly enhanced expression of M3a-Ld molecules in a dose- dependent manner, suggesting stabilization of unoccupied molecules. Stable association of beta 2-microglobulin with the chimeric H chain was observed in labeled cell lysates only in the presence of exogenous specific peptide, indicating that peptide is required for the formation of a ternary complex. These results indicate that surface expression of M3a-Ld is limited largely by the steady-state availability of endogenous peptides. Since most known M3a-binding peptides are N- formylated, native M3a may normally be expressed at high levels only during infection by intracellular bacteria. PMID:8270862

Lessons from Interspecies Mammalian Chimeras.

Science.gov (United States)

Suchy, Fabian; Nakauchi, Hiromitsu

2017-10-06

As chimeras transform from beasts of Greek mythology into tools of contemporary bioscience, secrets of developmental biology and evolutionary divergence are being revealed. Recent advances in stem cell biology and interspecies chimerism have generated new models with extensive basic and translational applications, including generation of transplantable, patient-specific organs.

CAPRRESI: Chimera Assembly by Plasmid Recovery and Restriction Enzyme Site Insertion.

Science.gov (United States)

Santillán, Orlando; Ramírez-Romero, Miguel A; Dávila, Guillermo

2017-06-25

Here, we present chimera assembly by plasmid recovery and restriction enzyme site insertion (CAPRRESI). CAPRRESI benefits from many strengths of the original plasmid recovery method and introduces restriction enzyme digestion to ease DNA ligation reactions (required for chimera assembly). For this protocol, users clone wildtype genes into the same plasmid (pUC18 or pUC19). After the in silico selection of amino acid sequence regions where chimeras should be assembled, users obtain all the synonym DNA sequences that encode them. Ad hoc Perl scripts enable users to determine all synonym DNA sequences. After this step, another Perl script searches for restriction enzyme sites on all synonym DNA sequences. This in silico analysis is also performed using the ampicillin resistance gene (ampR) found on pUC18/19 plasmids. Users design oligonucleotides inside synonym regions to disrupt wildtype and ampR genes by PCR. After obtaining and purifying complementary DNA fragments, restriction enzyme digestion is accomplished. Chimera assembly is achieved by ligating appropriate complementary DNA fragments. pUC18/19 vectors are selected for CAPRRESI because they offer technical advantages, such as small size (2,686 base pairs), high copy number, advantageous sequencing reaction features, and commercial availability. The usage of restriction enzymes for chimera assembly eliminates the need for DNA polymerases yielding blunt-ended products. CAPRRESI is a fast and low-cost method for fusing protein-coding genes.

Persistent Low-Level Replication of SIVΔnef Drives Maturation of Antibody and CD8 T Cell Responses to Induce Protective Immunity against Vaginal SIV Infection.

Directory of Open Access Journals (Sweden)

Sama Adnan

2016-12-01

Full Text Available Defining the correlates of immune protection conferred by SIVΔnef, the most effective vaccine against SIV challenge, could enable the design of a protective vaccine against HIV infection. Here we provide a comprehensive assessment of immune responses that protect against SIV infection through detailed analyses of cellular and humoral immune responses in the blood and tissues of rhesus macaques vaccinated with SIVΔnef and then vaginally challenged with wild-type SIV. Despite the presence of robust cellular immune responses, animals at 5 weeks after vaccination displayed only transient viral suppression of challenge virus, whereas all macaques challenged at weeks 20 and 40 post-SIVΔnef vaccination were protected, as defined by either apparent sterile protection or significant suppression of viremia in infected animals. Multiple parameters of CD8 T cell function temporally correlated with maturation of protection, including polyfunctionality, phenotypic differentiation, and redistribution to gut and lymphoid tissues. Importantly, we also demonstrate the induction of a tissue-resident memory population of SIV-specific CD8 T cells in the vaginal mucosa, which was dependent on ongoing low-level antigenic stimulation. Moreover, we show that vaginal and serum antibody titers inversely correlated with post-challenge peak viral load, and we correlate the accumulation and affinity maturation of the antibody response to the duration of the vaccination period as well as to the SIVΔnef antigenic load. In conclusion, maturation of SIVΔnef-induced CD8 T cell and antibody responses, both propelled by viral persistence in the gut mucosa and secondary lymphoid tissues, results in protective immune responses that are able to interrupt viral transmission at mucosal portals of entry as well as potential sites of viral dissemination.

Construction of RNA-Quantum Dot Chimera for Nanoscale Resistive Biomemory Application.

Science.gov (United States)

Lee, Taek; Yagati, Ajay Kumar; Pi, Fengmei; Sharma, Ashwani; Choi, Jeong-Woo; Guo, Peixuan

2015-07-28

RNA nanotechnology offers advantages to construct thermally and chemically stable nanoparticles with well-defined shape and structure. Here we report the development of an RNA-QD (quantum dot) chimera for resistive biomolecular memory application. Each QD holds two copies of the pRNA three-way junction (pRNA-3WJ) of the bacteriophage phi29 DNA packaging motor. The fixed quantity of two RNAs per QD was achieved by immobilizing the pRNA-3WJ with a Sephadex aptamer for resin binding. Two thiolated pRNA-3WJ serve as two feet of the chimera that stand on the gold plate. The RNA nanostructure served as both an insulator and a mediator to provide defined distance between the QD and gold. Immobilization of the chimera nanoparticle was confirmed with scanning tunneling microscopy. As revealed by scanning tunneling spectroscopy, the conjugated pRNA-3WJ-QD chimera exhibited an excellent electrical bistability signal for biomolecular memory function, demonstrating great potential for the development of resistive biomolecular memory and a nano-bio-inspired electronic device for information processing and computing.

Diversity of chimera-like patterns from a model of 2D arrays of neurons with nonlocal coupling

Science.gov (United States)

Tian, Chang-Hai; Zhang, Xi-Yun; Wang, Zhen-Hua; Liu, Zong-Hua

2017-06-01

Chimera states have been studied in 1D arrays, and a variety of different chimera states have been found using different models. Research has recently been extended to 2D arrays but only to phase models of them. Here, we extend it to a nonphase model of 2D arrays of neurons and focus on the influence of nonlocal coupling. Using extensive numerical simulations, we find, surprisingly, that this system can show most types of previously observed chimera states, in contrast to previous models, where only one or a few types of chimera states can be observed in each model. We also find that this model can show some special chimera-like patterns such as gridding and multicolumn patterns, which were previously observed only in phase models. Further, we present an effective approach, i.e., removing some of the coupling links, to generate heterogeneous coupling, which results in diverse chimera-like patterns and even induces transformations from one chimera-like pattern to another.

A chimera embryo assay reveals a decrease in embryonic cellular proliferation induced by sperm from X-irradiated male mice

International Nuclear Information System (INIS)

Obasaju, M.F.; Wiley, L.M.; Oudiz, D.J.; Raabe, O.; Overstreet, J.W.

1989-01-01

Male mice were divided into three experimental groups and a control group. Mice in the experimental groups received one of three doses of acute X irradiation (1.73, 0.29, and 0.05 Gy) and together with the control unirradiated mice were then mated weekly to unirradiated female mice for a 9-week experimental period. Embryos were recovered from the weekly matings at the four-cell stage and examined by the chimera assay for proliferative disadvantage. Aggregation chimeras were constructed of embryos from female mice mated to irradiated males (experimental embryos) and embryos from females mated to unexposed males (control embryos) and contained either one experimental embryo and one control embryo (heterologous chimera) or two control embryos (control chimera). The control embryo in heterologous chimeras and either embryo in control chimeras were prelabeled with the vital dye fluorescein isothiocyanate (FITC), and the chimeras were cultured for 40 h and viewed under phase-contrast and epifluorescence microscopy to obtain total embryo cell number and the cellular contribution from the FITC-labeled embryo. Experimental and control embryos that were cultured singly were also examined for embryo cell number at the end of the 40-h culture period. In control chimeras, the mean ratio of the unlabeled cells:total chimera cell number (henceforth referred to as ''mean ratio'') was 0.50 with little or no weekly variation over the 9-week experimental period. During Weeks 4-7, the mean ratios of heterologous chimeras differed significantly from the mean ratio of control chimeras with the greatest differences occurring during Week 7 (0.41 for chimeras of 0.05 Gy dose group, 0.40 for chimeras of the 0.29 Gy dose group, and 0.17 for chimeras of the 1.73 Gy dose group)

Basins of Attraction for Chimera States

DEFF Research Database (Denmark)

Martens, Erik Andreas; Panaggio, Mark; Abrams, Daniel

2016-01-01

Chimera states---curious symmetry-broken states in systems of identical coupled oscillators---typically occur only for certain initial conditions. Here we analyze their basins of attraction in a simple system comprised of two populations. Using perturbative analysis and numerical simulation we...

Intermittent chaotic chimeras for coupled rotators

DEFF Research Database (Denmark)

Olmi, Simona; Martens, Erik Andreas; Thutupalli, Shashi

2015-01-01

Two symmetrically coupled populations of N oscillators with inertia m display chaotic solutions with broken symmetry similar to experimental observations with mechanical pendulums. In particular, we report evidence of intermittent chaotic chimeras, where one population is synchronized and the other...

Four-cluster chimera state in non-locally coupled phase oscillator systems with an external potential

International Nuclear Information System (INIS)

Zhu Yun; Zheng Zhi-Gang; Yang Jun-Zhong

2013-01-01

Dynamics of a one-dimensional array of non-locally coupled Kuramoto phase oscillators with an external potential is studied. A four-cluster chimera state is observed for the moderate strength of the external potential. Different from the clustered chimera states studied before, the instantaneous frequencies of the oscillators in a synchronized cluster are different in the presence of the external potential. As the strength of the external potential increases, a bifurcation from the two-cluster chimera state to the four-cluster chimera states can be found. These phenomena are well predicted analytically with the help of the Ott—Antonsen ansatz. (general)

Infusion of donor lymphocytes into stable canine radiation chimeras: implications for mechanism of transplantation tolerance

International Nuclear Information System (INIS)

Weiden, P.L.; Storb, R.; Tsoi, M.S.; Graham, T.C.; Lerner, K.G.; Thomas, E.D.

1976-01-01

Canine radiation chimeras were used to investigate further mechanism(s) responsible for maintaining the stable chimeric state. In an attempt to elucidate the nature of this postulated active mechanism, the cytotoxicity of donor lymphocytes for fibroblasts of the chimera and the presence or absence of serum-blocking factors were assessed in vitro by using a cellular inhibition (CI) assay. The presence of serum-blocking factors did not protect against the development of significant GVHD in two chimeras (fatal in one). GVHD did not occur in four other chimeras after infusion of cytotoxic donor lymphocytes despite the absence of serum-blocking factors. These and previous results suggest that serum-blocking factors are not the mechanism suppressing the development of GVHD in canine radiation chimeras, and raise the possibility that a suppressor cell population may be responsible for preventing GVHD

Phenotypic characterization of early events of thymus repopulation in radiation bone marrow chimeras

International Nuclear Information System (INIS)

Sharrow, S.O.; Singer, A.; Hammerling, U.; Mathieson, B.J.

1983-01-01

The phenotype of murine thymocytes repopulating the thymus of radiation bone marrow chimeras shortly after irradiation and bone marrow reconstitution was analyzed by immunofluorescence and flow microfluorometry. Thymuses in these chimeras, while essentially devoid of lymphoid cells at day 7, were repopulated by days 10 to 12 after irradiation. It was found that this initial repopulation arose from a radioresistant intrathymic precursor that expanded to an almost complete complement of host-type thymocytes. However, these host-derived thymocytes were unusual in that they were relatively deficient in Lyt 1+2- and peanut agglutinin ''dull'' cells as compared with normal thymocytes. Donor bone-marrow-derived cells first appeared in the irradiated chimeric thymuses between days 12 and 15 after irradiation and bone marrow transfer. By day 19, chimeric thymuses contained more than 98% donor cells. This course was identical for three chimeric combinations, each made across different genetic barriers. In contrast to the cells that populate the fetal thymus during normal ontogeny, the first donor bone-marrow-derived cells that can be detected within the irradiated chimeric thymuses already expressed phenotypically normal adult T cell subpopulations in that they contained significant numbers both of Lyt 1+2- and of Lyt 1+2+ thymocytes. Thus, the Lyt phenotype of donor cells that initially repopulate an adult thymus after irradiation is markedly different from the Lyt phenotype of cells that initially populate the fetal thymus. The differences between adult and fetal thymic development that are observed in radiation bone marrow chimeras may be important in our understanding of T cell differentiation in these animals

Secondary Disease in Radiation Chimeras

Energy Technology Data Exchange (ETDEWEB)

Congdon, C. C. [Biology Division, Oak Ridge National Laboratory, Oak Ridge, TN (United States)

1969-07-15

A review of research dealing directly or indirectly with the development of bidirectional tolerance in radiation chimeras has been made, emphasizing some of the contemporary research on this subject in Oak Ridge and Knoxville. By controlling such factors as cell dose, age of donor animal and day of cell injection, it was possible to achieve bidirectional tolerance. Attempts to reduce bidirectional tolerance in favour of increasing the graft-versus-host reaction were less successful. Hypoxic caging demonstrated a new approach to achieving bidirectional tolerance through physiological competition for growth. Graft-versus-host reactions have a lower growth priority than marrow regeneration or erythropoietic hyperplasia. Study of pathologic processes, immunologic capability and the-biochemical lesions in radiation chimeras all lead to new ideas that involve bidirectional tolerance. The investigations on dose rate in radiation suppression of the immune response and on LD{sub 50} (30- to 90-day)values after injection of different numbers of marrow cells all have a bearing on control of the host-versus-graft response and therefore are important in understanding bidirectional tolerance. (author)

Chimera Type Behavior in Nonlocal Coupling System with Two Different Inherent Frequencies

Science.gov (United States)

Lin, Larry; Li, Ping-Cheng; Tseng, Hseng-Che

2014-03-01

From the research of Kuramoto and Strogatz, arrays of identical oscillators can display a remarkable pattern, named chimera state, in which phase-locked oscillators coexist with drifting ones in nonlocal coupling oscillator system. We consider further in this study, two groups of oscillators with different inherent frequencies and arrange them in a ring. When the difference of the inherent frequencies is within some specific parameter range, oscillators of nonlocal coupling system show two distinct chimera states. When the parameter value exceeds some threshold value, two chimera states disappear. They show different features. The statistical dynamic behavior of the system can be described by Kuramoto theory.

HIV-1 Env and Nef Cooperatively Contribute to Plasmacytoid Dendritic Cell Activation via CD4-Dependent Mechanisms.

Science.gov (United States)

Reszka-Blanco, Natalia J; Sivaraman, Vijay; Zhang, Liguo; Su, Lishan

2015-08-01

Plasmacytoid dendritic cells (pDCs) are the major source of type I IFN (IFN-I) in response to human immunodeficiency virus type 1 (HIV-1) infection. pDCs are rapidly activated during HIV-1 infection and are implicated in reducing the early viral load, as well as contributing to HIV-1-induced pathogenesis. However, most cell-free HIV-1 isolates are inefficient in activating human pDCs, and the mechanisms of HIV-1 recognition by pDCs and pDC activation are not clearly defined. In this study, we report that two genetically similar HIV-1 variants (R3A and R3B) isolated from a rapid progressor differentially activated pDCs to produce alpha interferon (IFN-α). The highly pathogenic R3A efficiently activated pDCs to induce robust IFN-α production, while the less pathogenic R3B did not. The viral determinant for efficient pDC activation was mapped to the V1V2 region of R3A Env, which also correlated with enhanced CD4 binding activity. Furthermore, we showed that the Nef protein was also required for the activation of pDCs by R3A. Analysis of a panel of R3A Nef functional mutants demonstrated that Nef domains involved in CD4 downregulation were necessary for R3A to activate pDCs. Our data indicate that R3A-induced pDC activation depends on (i) the high affinity of R3A Env for binding the CD4 receptor and (ii) Nef activity, which is involved in CD4 downregulation. Our findings provide new insights into the mechanism by which HIV-1 induces IFN-α in pDCs, which contributes to pathogenesis. Plasmacytoid dendritic cells (pDCs) are the major type I interferon (IFN-I)-producing cells, and IFN-I actually contributes to pathogenesis during chronic viral infections. How HIV-1 activates pDCs and the roles of pDCs/IFN-I in HIV-1 pathogenesis remain unclear. We report here that the highly pathogenic HIV R3A efficiently activated pDCs to induce IFN-α production, while most HIV-1 isolates are inefficient in activating pDCs. We have discovered that R3A-induced pDC activation depends on

Chimeras of Bet v 1 and Api g 1 reveal heterogeneous IgE responses in patients with birch pollen allergy.

Science.gov (United States)

Gepp, Barbara; Lengger, Nina; Bublin, Merima; Hemmer, Wolfgang; Breiteneder, Heimo; Radauer, Christian

2014-07-01

Characterization of IgE-binding epitopes of allergens and determination of their patient-specific relevance is crucial for the diagnosis and treatment of allergy. We sought to assess the contribution of specific surface areas of the major birch pollen allergen Bet v 1.0101 to binding IgE of individual patients. Four distinct areas of Bet v 1 representing in total 81% of its surface were grafted onto the scaffold of its homolog, Api g 1.0101, to yield the chimeras Api-Bet-1 to Api-Bet-4. The chimeras were expressed in Escherichia coli and purified. IgE binding of 64 sera from Bet v 1-sensitized subjects with birch pollen allergy was determined by using direct ELISA. Specificity was assessed by means of inhibition ELISA. rApi g 1.0101, Api-Bet-1, Api-Bet-2, Api-Bet-3, and Api-Bet-4 bound IgE from 44%, 89%, 80%, 78%, and 48% of the patients, respectively. By comparing the amount of IgE binding to the chimeras and to rApi g 1.0101, 81%, 70%, 75%, and 45% of the patients showed significantly enhanced IgE binding to Api-Bet-1, Api-Bet-2, Api-Bet-3, and Api-Bet-4, respectively. The minority (8%) of the sera revealed enhanced IgE binding exclusively to a single chimera, whereas 31% showed increased IgE binding to all 4 chimeras compared with rApi g 1.0101. The chimeras inhibited up to 70% of IgE binding to rBet v 1.0101, confirming the specific IgE recognition of the grafted regions. The Bet v 1-specific IgE response is polyclonal, and epitopes are spread across the entire Bet v 1 surface. Furthermore, the IgE recognition profile of Bet v 1 is highly patient specific. Copyright © 2014 The Authors. Published by Mosby, Inc. All rights reserved.

Advances in Chimera Grid Tools for Multi-Body Dynamics Simulations and Script Creation

Science.gov (United States)

Chan, William M.

2004-01-01

This viewgraph presentation contains information about (1) Framework for multi-body dynamics - Geometry Manipulation Protocol (GMP), (2) Simulation procedure using Chimera Grid Tools (CGT) and OVERFLOW-2 (3) Further recent developments in Chimera Grid Tools OVERGRID, Grid modules, Script library and (4) Future work.

Complement factor 5a receptor chimeras reveal the importance of lipid-facing residues in transport competence

DEFF Research Database (Denmark)

Klco, Jeffery M; Sen, Saurabh; Hansen, Jakob L

2009-01-01

. Despite relatively conservative substitutions, the lipid-facing chimeras (TM1, TM2, TM4, TM5, TM6 or TM7) were retained in the endoplasmic reticulum/cis-Golgi network. With the exception of the TM7 chimera that did not bind ligand, the lipid-facing chimeras bound ligand with low affinity, but similar...... oligomerization studies demonstrated energy transfer between the wild-type complement factor 5a receptor and the lipid-facing chimeras, suggesting that the lipid-facing residues within a single TM segment are not essential for oligomerization. These studies highlight the importance of the lipid-facing residues...

Chimera states in an ensemble of linearly locally coupled bistable oscillators

Science.gov (United States)

Shchapin, D. S.; Dmitrichev, A. S.; Nekorkin, V. I.

2017-11-01

Chimera states in a system with linear local connections have been studied. The system is a ring ensemble of analog bistable self-excited oscillators with a resistive coupling. It has been shown that the existence of chimera states is not due to the nonidentity of oscillators and noise, which is always present in real experiments, but is due to the nonlinear dynamics of the system on invariant tori with various dimensions.

Multiclustered chimeras in large semiconductor laser arrays with nonlocal interactions

Science.gov (United States)

Shena, J.; Hizanidis, J.; Hövel, P.; Tsironis, G. P.

2017-09-01

The dynamics of a large array of coupled semiconductor lasers is studied numerically for a nonlocal coupling scheme. Our focus is on chimera states, a self-organized spatiotemporal pattern of coexisting coherence and incoherence. In laser systems, such states have been previously found for global and nearest-neighbor coupling, mainly in small networks. The technological advantage of large arrays has motivated us to study a system of 200 nonlocally coupled lasers with respect to the emerging collective dynamics. Moreover, the nonlocal nature of the coupling allows us to obtain robust chimera states with multiple (in)coherent domains. The crucial parameters are the coupling strength, the coupling phase and the range of the nonlocal interaction. We find that multiclustered chimera states exist in a wide region of the parameter space and we provide quantitative characterization for the obtained spatiotemporal patterns. By proposing two different experimental setups for the realization of the nonlocal coupling scheme, we are confident that our results can be confirmed in the laboratory.

Chimera and phase-cluster states in populations of coupled chemical oscillators

Science.gov (United States)

Tinsley, Mark R.; Nkomo, Simbarashe; Showalter, Kenneth

2012-09-01

Populations of coupled oscillators may exhibit two coexisting subpopulations, one with synchronized oscillations and the other with unsynchronized oscillations, even though all of the oscillators are coupled to each other in an equivalent manner. This phenomenon, discovered about ten years ago in theoretical studies, was then further characterized and named the chimera state after the Greek mythological creature made up of different animals. The highly counterintuitive coexistence of coherent and incoherent oscillations in populations of identical oscillators, each with an equivalent coupling structure, inspired great interest and a flurry of theoretical activity. Here we report on experimental studies of chimera states and their relation to other synchronization states in populations of coupled chemical oscillators. Our experiments with coupled Belousov-Zhabotinsky oscillators and corresponding simulations reveal chimera behaviour that differs significantly from the behaviour found in theoretical studies of phase-oscillator models.

Importance of M2-M3 loop in governing properties of genistein at the α7 nicotinic acetylcholine receptor inferred from α7/5-HT3A chimera.

Science.gov (United States)

Grønlien, Jens Halvard; Ween, Hilde; Thorin-Hagene, Kirsten; Cassar, Steven; Li, Jinhe; Briggs, Clark A; Gopalakrishnan, Murali; Malysz, John

2010-11-25

Genistein and 5-hydroxyindole (5-HI) potentiate the α7 nicotinic acetylcholine receptor current by primarily increasing peak amplitude, a property of type I α7 positive allosteric modulation. In this study, the effects of these two compounds were investigated at two different α7/5-HT(3) chimeras (chimera 1, comprising of extracellular α7 N-terminus fused to the remainder of 5-HT(3A), and chimera 2 containing an additional α7 encoded M2-M3 loop), and wild-type α7 and 5-HT(3A) receptors. Agonist-evoked responses, examined by expression of the chimeras in Xenopus laevis oocytes or HEK-293 cells, revealed that currents decayed slower and compounds {rank order: N-[(3R)-1-azabicyclo[2.2.2]oct-3-yl]-4-chlorobenzamide hydrochloride (PNU-282987)~2-(1,4-diazabicyclo[3.2.2]nonan-4-yl)-5-phenyl-1,3,4-oxadiazole (NS6784)>acetylcholine>choline} were more potent in chimera 2 than chimera 1 or α7 receptors. In chimera 2, genistein and 5-HI potentiated agonist-evoked responses (EC(50): 4-5 μM for genistein and 300-500 μM for 5-HI) and at higher concentrations evoked current directly consistent with ago-allosteric modulation. At chimera 1 and 5-HT(3A) receptors, neither compound directly evoked any current and 5-HI, only at chimera 1, was able to potentiate agonist-evoked responses. Genistein and 5-HI did not inhibit the binding of the α7 agonist [(3)H](1S,4S)-2,2-dimethyl-5-(6-phenylpyridazin-3-yl)-5-aza-2-azoniabicyclo[2.2.1] heptane ([(3)H]A-585539) to rat brain or chimera 2. In summary, this study supports the role of the M2-M3 loop being critical for the positive allosteric effect of genistein, but not 5-HI, and in agonist-evoked response fine-tuning. The identification of distinct α7 receptor modulatory sites offers unique opportunities for developing CNS therapeutics and understanding its pharmacology. Copyright © 2010 Elsevier B.V. All rights reserved.

Immune responsiveness and incidence of reticulum cell sarcoma in long-term syngeneic radiation chimeras

International Nuclear Information System (INIS)

Adorini, L.; Gorini, G.; Covelli, V.; Ballardin, E.; di Michele, A.; Bassani, B.; Metalli, P.; Doria, G.

1976-01-01

Long-term syngeneic radiation chimeras displayed a very low incidence of reticulum cell sarcoma as compared with control mice. Immune reactivity of these animals was studied in vivo by anti-dinitrophenyl antibody titer and affinity and in vitro by mitotic responsiveness to phytohemagglutinin, concanavalin A and lipopolysaccharide. Antibody titer and affinity as well as the response to T lectins were found to be increased in chimeras. These results were attributed to increased function of mature T2 cells, which could explain the reduced incidence of reticulum cell sarcoma in chimeras

Application of a Chimera Full Potential Algorithm for Solving Aerodynamic Problems

Science.gov (United States)

Holst, Terry L.; Kwak, Dochan (Technical Monitor)

1997-01-01

A numerical scheme utilizing a chimera zonal grid approach for solving the three dimensional full potential equation is described. Special emphasis is placed on describing the spatial differencing algorithm around the chimera interface. Results from two spatial discretization variations are presented; one using a hybrid first-order/second-order-accurate scheme and the second using a fully second-order-accurate scheme. The presentation is highlighted with a number of transonic wing flow field computations.

Status of T- and B-cell cooperation in radiation chimeras: evidence for a suppressor effect

International Nuclear Information System (INIS)

Gengozian, N.; Urso, P.

1976-01-01

Absolute tolerance may not be in operation in the allogeneic bone marrow chimera, but rather a dynamic state involving interaction not only between the donor and host but also among the donor-lymphoid cells themselves may exist. Whether this observation made in one allogeneic chimera, CD2F 1 → C3BF 1 , will be true for other chimeras (different strain combinations, species) remains to be shown. Thus, the tempo, mode, and requirement for the generation of suppressor T cells are factors that may vary for any specific allogeneic bone marrow transplant. Finally, the manner and degree to which the tolerance-inducing mechanism may affect T- and B-cell functions of the chimera with respect to third-party antigens are yet to be determined

The Chimera II Real-Time Operating System for advanced sensor-based control applications

Science.gov (United States)

Stewart, David B.; Schmitz, Donald E.; Khosla, Pradeep K.

1992-01-01

Attention is given to the Chimera II Real-Time Operating System, which has been developed for advanced sensor-based control applications. The Chimera II provides a high-performance real-time kernel and a variety of IPC features. The hardware platform required to run Chimera II consists of commercially available hardware, and allows custom hardware to be easily integrated. The design allows it to be used with almost any type of VMEbus-based processors and devices. It allows radially differing hardware to be programmed using a common system, thus providing a first and necessary step towards the standardization of reconfigurable systems that results in a reduction of development time and cost.

T lymphocytes from irradiation chimeras repopulated with 13-day fetal liver cells recognize antigens only in association with self-MHC products

International Nuclear Information System (INIS)

Nisbet-Brown, E.; Diener, E.

1986-01-01

The restriction specificities of maturing thymocytes are determined by the Class II MHC antigens expressed by non-lymphoid thymic tissues. The proliferative response of mature T lymphocytes to antigen-presenting cells (APC) and antigen requires that the APC express the same MHC antigens as the thymus in which the T cells differentiated. Thus, in the two-way bone marrow chimera [A + B----(A x B)F1], T lymphocyte populations of A and B haplotypes have each acquired the potential to recognize antigens associated with either parental haplotype. In spite of the large body of work on MHC restriction, we still do not have a clear understanding of the mechanisms which impose self restriction. The chimeric model systems used previously to study MHC restriction have used adult bone marrow cells as the source of lymphoid precursors. During normal ontogeny, T cells are derived from precursors in the fetal liver and we felt that a direct comparison of T cells from fetal liver and bone marrow-repopulated animals would shed light on the development of MHC restriction specificities during T cell ontogeny in the thymus or prethymically. We found that parental T lymphocyte populations isolated from two-way fetal liver chimeras cooperated only with syngeneic APC, while those from bone marrow chimeras cooperated with APC of either parental haplotype. This suggests that fetal liver and bone marrow may not be equivalent sources of stem cells. Our results may be due to fundamental differences between thymocyte precursors in fetal liver and bone marrow, including the time course of their expression of T cell receptor gene products

A Phase 1 Study of 4 Live, Recombinant Human Cytomegalovirus Towne/Toledo Chimera Vaccines in Cytomegalovirus-Seronegative Men.

Science.gov (United States)

Adler, Stuart P; Manganello, Anne-Marie; Lee, Ronzo; McVoy, Michael A; Nixon, Daniel E; Plotkin, Stanley; Mocarski, Edward; Cox, Josephine H; Fast, Patricia E; Nesterenko, Pavlo A; Murray, Susan E; Hill, Ann B; Kemble, George

2016-11-01

 Human cytomegalovirus (HCMV) infection causes disease in newborns and transplant recipients. A HCMV vaccine (Towne) protects transplant recipients.  The genomes of Towne and the nonattenuated Toledo strain were recombined, yielding 4 Towne/Toledo chimera vaccines. Each of 36 HCMV-seronegative men received 1 subcutaneous dose of 10, 100, or 1000 plaque-forming units (PFU) in cohorts of 3. Safety and immunogenicity were evaluated over 12 weeks after immunization and for 52 weeks for those who seroconverted.  There were no serious local or systemic reactions. No subject had HCMV in urine or saliva. For chimera 3, none of 9 subjects seroconverted. For chimera 1, 1 of 9 seroconverted (the seroconverter received 100 PFU). For chimera 2, 3 subjects seroconverted (1 received 100 PFU, and 2 received 1000 PFU). For chimera 4, 7 subjects seroconverted (1 received 10 PFU, 3 received 100 PFU, and 3 received 1000 PFU). All 11 seroconverters developed low but detectable levels of neutralizing activity. CD4 + T-cell responses were detectable in 1 subject (who received 100 PFU of chimera 4). Seven subjects receiving chimera 2 or 4 had detectable CD8 + T-cell responses to IE1; 3 responded to 1-2 additional antigens.  The Towne/Toledo chimera vaccine candidates were well tolerated and were not excreted. Additional human trials of chimeras 2 and 4 are appropriate.  NCT01195571. © The Author 2016. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail journals.permissions@oup.com.

Anticipatory Governance: Bioethical Expertise for Human/Animal Chimeras

Science.gov (United States)

Harvey, Alison; Salter, Brian

2012-01-01

The governance demands generated by the use of human/animal chimeras in scientific research offer both a challenge and an opportunity for the development of new forms of anticipatory governance through the novel application of bioethical expertise. Anticipatory governance can be seen to have three stages of development whereby bioethical experts move from a reactive to a proactive stance at the edge of what is scientifically possible. In the process, the ethicists move upstream in their engagement with the science of human-to-animal chimeras. To what extent is the anticipatory coestablishment of the principles and operational rules of governance at this early stage in the development of the human-to-animal research field likely to result in a framework for bioethical decision making that is in support of science? The process of anticipatory governance is characterised by the entwining of the scientific and the philosophical so that judgements against science are also found to be philosophically unfounded, and conversely, those activities that are permissible are deemed so on both scientific and ethical grounds. Through what is presented as an organic process, the emerging bioethical framework for human-to-animal chimera research becomes a legitimating framework within which ‘good’ science can safely progress. Science gives bioethical expertise access to new governance territory; bioethical expertise gives science access to political acceptability. PMID:23576848

Chimera at the phase-flip transition of an ensemble of identical nonlinear oscillators

Science.gov (United States)

Gopal, R.; Chandrasekar, V. K.; Senthilkumar, D. V.; Venkatesan, A.; Lakshmanan, M.

2018-06-01

A complex collective emerging behavior characterized by coexisting coherent and incoherent domains is termed as a chimera state. We bring out the existence of a new type of chimera in a nonlocally coupled ensemble of identical oscillators driven by a common dynamic environment. The latter facilitates the onset of phase-flip bifurcation/transitions among the coupled oscillators of the ensemble, while the nonlocal coupling induces a partial asynchronization among the out-of-phase synchronized oscillators at this onset. This leads to the manifestation of coexisting out-of-phase synchronized coherent domains interspersed by asynchronous incoherent domains elucidating the existence of a different type of chimera state. In addition to this, a rich variety of other collective behaviors such as clusters with phase-flip transition, conventional chimera, solitary state and complete synchronized state which have been reported using different coupling architectures are found to be induced by the employed couplings for appropriate coupling strengths. The robustness of the resulting dynamics is demonstrated in ensembles of two paradigmatic models, namely Rössler oscillators and Stuart-Landau oscillators.

Allogeneic unresponsiveness to orthotopic cardiac transplants in DL-A-identical radiation chimeras

International Nuclear Information System (INIS)

Boyd, A.D.; Spencer, F.C.; Hirose, H.; Engelman, R.M.; Cannon, F.D.; Ferrebee, J.W.; Rapaport, F.T.

1975-01-01

Nine Cooperstown beagles of known DL-A genotypes were exposed to supralethal total-body irradiation and received bone-marrow allografts from DL-A-identical donors. Four to 5 months later, the resulting chimeras received orthotopic cardiac allografts from their corresponding donors of marrow. Six chimeras died of operative complications in the immediate postoperative period. The other 3 chimeras survived from 173 to 547 days; 1 dog died at 173 days as a result of right-sided heart failure, secondary to stenosis at the site of the pulmonary artery anastomosis. The other two recipients continue to be active and healthy at 545 and 547 days. The results indicate that dogs can be rendered specifically tolerant to orthotopic cardiac allografts by supralethal total-body irradiation and the transplantation of marrow obtained from the prospective allograft donor

Exceptional curves on smooth rational surfaces with -K not nef and of self-intersection zero

International Nuclear Information System (INIS)

Lahyane, Mustapha

2001-08-01

We prove that a smooth rational surface X defined over the field of complex numbers having an anti-canonical divisor not nef and of self-intersection zero has a finite number of (-1)-curves. A (-1)-curve is a smooth rational curve of self-interaction -1. By giving an example, we also show that X may have no (-2)-curves, a (-2)-curve is a smooth rational curve of self-intersection -2. (author)

Immune competence of splenic lymphocytes following graft-vs-host disease in mouse allogeneic radiation chimeras

International Nuclear Information System (INIS)

Urso, P.; Gengozian, N.

1977-01-01

The abnormal immune response of long-term mouse allogeneic chimeras is reflected by qualitative deficiencies in either T or B lymphocytes. The present study was undertaken to determine if a relationship existed between the severity of graft-vs-host disease (GVHD) that these animals had experienced and a functional defect in either the T or B cell population. The in vitro PFC response of chimera spleen cells to sheep red blood cells (SRBC) was evaluated in the presence of normal T or B lymphocytes 4 to 8 months after marrow transplantation and well beyond the GVHD period. In an analysis of several different allogeneic radiation chimeras, our results showed no relationship between the severity of GVHD experienced and the immunologic capacity of either T or B cells. Thus, different chimera combinations showing similar degrees of GVHD were functionally deficient in one or the other of these two cells types or both with no apparent predilection for abnormality in either population. In examining the quantitative in vitro PFC response to sheep RBC by spleen cells from individual chimeras, we found that the number of PFC formed was related to the severity of GVHD experienced by that animal. A general relationship between severity of GVHD and PFC capacity may also exist between chimeras of different genetic combinations. However, this relationship is not precise since gross exceptions occur. Our results, although documenting further the qualitative abnormalities in T and/or B lymphocytes of radiation chimeras, do not reveal the factor or mechanisms by which these cells are made unresponsive. It is suggested that the tolerance-inducing mechanism of these animals, whether it be humoral blocking factors or suppressor cells, is in some way interfering with the collaboration of T and B cells for antibody production

Cell surface appearance of unexpected host MHC determinants on thymocytes from radiation bone marrow chimeras

International Nuclear Information System (INIS)

Sharrow, S.O.; Mathieson, B.J.; Singer, A.

1981-01-01

The phenotypic appearance of cell surface antigens on murine thymocytes from long-term radiation bone marrow chimeras was analyzed using indirect immunofluorescence and flow microfluorometry. Cells maturing in the thymi of these mice were typed for MHC (Kk, I-Ak, H-2b, Kb, and Ib) and non-MHC (Lty 1, Ly 9, and TL) determinants. All cells were of donor origin as determined by non-MHC (Ly) phenotype in P1 leads to P2, P1 x P2 leads to P1, and P1 leads to P2 radiation chimeras. In contrast, the MHC phenotypes of these thymocytes were markedly affected by the host environment. Specifically, H-2 and I-A determinants of both parental phenotypes were detected on thymocytes from P1 leads to P1 x P2 chimeras; I-A determinants of host phenotype were present, whereas I-A determinants of donor phenotype were reduced on thymocytes from P1 x P2 leads to P1 chimeras; and thymocytes from P1 leads to P2 chimeras possessed H-2 and I-A determinants of host phenotype but showed reduction of donor I-A phenotype determinants. The appearance of host cell surface H-2 and I-A determinants on thymocytes from chimeras closely parallels the functional recognition of MHC determinants by T cells from chimeric mice and thus may be significantly related to the development of the self-recognition repertoire by maturing T cells

Growth control of genetically modified cells using an antibody/c-Kit chimera.

Science.gov (United States)

Kaneko, Etsuji; Kawahara, Masahiro; Ueda, Hiroshi; Nagamune, Teruyuki

2012-05-01

Gene therapy has been regarded as an innovative potential treatment against serious congenital diseases. However, applications of gene therapy remain limited, partly because its clinical success depends on therapeutic gene-transduced cells acquiring a proliferative advantage. To address this problem, we have developed the antigen-mediated genetically modified cell amplification (AMEGA) system, which uses chimeric receptors to enable the selective proliferation of gene-transduced cells. In this report, we describe mimicry of c-Kit signaling and its application to the AMEGA system. We created an antibody/c-Kit chimera in which the extracellular domain of c-Kit is replaced with an anti-fluorescein single-chain Fv antibody fragment and the extracellular D2 domain of the erythropoietin receptor. A genetically modified mouse pro-B cell line carrying this chimera showed selective expansion in the presence of fluorescein-conjugated BSA (BSA-FL) as a growth inducer. By further engineering the transmembrane domain of the chimera to reduce interchain interaction we attained stricter ligand-dependency. Since c-Kit is an important molecule in the expansion of hematopoietic stem cells (HSCs), this antibody/c-Kit chimera could be a promising tool for gene therapy targeting HSCs. Copyright © 2011 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

What's Wrong with Human/Nonhuman Chimera Research?

Science.gov (United States)

Hyun, Insoo

2016-08-01

The National Institutes of Health (NIH) is poised to lift its funding moratorium on research involving chimeric human/nonhuman embryos, pending further consideration by an NIH steering committee. The kinds of ethical concerns that seem to underlie this research and chimera research more generally can be adequately addressed.

Antiviral T cell competence and restriction specificity of mixed allogeneic (P1 + P2----P1) irradiation chimeras

International Nuclear Information System (INIS)

Rueedi, E.S.; Sykes, M.; Ildstad, S.T.; Chester, C.H.; Althage, A.; Hengartner, H.; Sachs, D.H.; Zinkernagel, R.M.

1989-01-01

Mixed irradiation bone marrow chimeras were prepared by reconstituting lethally irradiated C57BL/10 (B10) or B10.D2 mice with T cell-depleted bone marrow cells of B10 plus B10.D2 origin. These chimeras were healthy and survived well under conventional housing conditions and after experimental laboratory infections. Of a total of 17 chimeras tested, 2 died spontaneously or from the injected virus. Twelve of fifteen chimeras mounted a measurable cytotoxic T cell response to virus. Despite approximately equal percentages of B10 and B10.D2 lymphocytes in chimeras, cytotoxic T cell responses to vaccinia virus and lymphocytic choriomeningitis virus were mediated variably by either syngeneic or allogeneic donor lymphocytes; thus the H-2 type of effector T cells frequently did not correspond to the 50:50 distribution of spleen or peripheral blood lymphocytes. Cytotoxic responses were restricted exclusively to recipient H-2 type. All mixed chimeras examined were able to mount a good IgG response to vesicular stomatitis virus. These results confirm previous data suggesting that such mixed chimeras are healthy and immunocompetent and demonstrate strict recipient-determined restriction specificity of effector T cells; they also suggest that if T help is necessary for induction of virus-specific cytotoxic T cells, it does not require host-restricted interactions between helper T cells and precursor cytotoxic T cells

Origin of hemopoietic stromal progenitor cells in chimeras

International Nuclear Information System (INIS)

Chertkov, J.L.; Drize, N.J.; Gurevitch, O.A.; Samoylova, R.S.

1985-01-01

Intravenously injected bone marrow cells do not participate in the regeneration of hemopoietic stromal progenitors in irradiated mice, nor in the curetted parts of the recipient's marrow. The hemopoietic stromal progenitors in allogeneic chimeras are of recipient origin. The adherent cell layer (ACL) of long-term cultures of allogeneic chimera bone marrow contains only recipient hemopoietic stromal progenitors. However, in ectopic hemopoietic foci produced by marrow implantation under the renal capsule and repopulated by the recipient hemopoietic cells after irradiation and reconstitution by syngeneic hemopoietic cells, the stromal progenitors were of implant donor origin, as were stromal progenitors of the ACL in long-term cultures of hemopoietic cells from ectopic foci. Our results confirm that the stromal and hemopoietic progenitors differ in origin and that hemopoietic stromal progenitors are not transplantable by the intravenous route in mice

The use of the mouse chimera assay to detect early embryonic damage from male mice exposed to low-dose radiation

International Nuclear Information System (INIS)

Oudiz, D.; Warner, P.; Walsh, K.J.; Wiley, L.

1990-01-01

Mouse chimeras are in vitro aggregations of two 4-cell embryos and are used to detect subtle, nonlethal changes, which are expressed as a proliferative disadvantage in exposed embryos. One of the embryos is labeled with a viable dye (FITC) in order to determine the relative cellular contribution of each embryo when the chimera is dissociated 40 hours later. This proliferative disadvantage has been seen at doses which do not produce an effect on cell number when the embryos are cultured singly. Previously, the assay has detected a decrease in cellular proliferation in embryos from male mice exposed to a single dose of x-radiation as low as 0.05 Gy. In the current study, male mice were irradiated with a single dose of 0, 0.001, 0.01, or 0.05 Gy, and then serially mated for the next 8 weeks to unexposed females. Chimeras were constructed from control and treated embryos. Embryos from males treated with 0.05 Gy exhibited a significant decrease in cellular proliferation during weeks 6 and 7 post-irradiation. A similar decrease was seen in the males treated with 0.01 Gy. No reductions were observed from embryos cultured singly in any of the treatment groups

Three-dimensional chimera patterns in networks of spiking neuron oscillators

Science.gov (United States)

Kasimatis, T.; Hizanidis, J.; Provata, A.

2018-05-01

We study the stable spatiotemporal patterns that arise in a three-dimensional (3D) network of neuron oscillators, whose dynamics is described by the leaky integrate-and-fire (LIF) model. More specifically, we investigate the form of the chimera states induced by a 3D coupling matrix with nonlocal topology. The observed patterns are in many cases direct generalizations of the corresponding two-dimensional (2D) patterns, e.g., spheres, layers, and cylinder grids. We also find cylindrical and "cross-layered" chimeras that do not have an equivalent in 2D systems. Quantitative measures are calculated, such as the ratio of synchronized and unsynchronized neurons as a function of the coupling range, the mean phase velocities, and the distribution of neurons in mean phase velocities. Based on these measures, the chimeras are categorized in two families. The first family of patterns is observed for weaker coupling and exhibits higher mean phase velocities for the unsynchronized areas of the network. The opposite holds for the second family, where the unsynchronized areas have lower mean phase velocities. The various measures demonstrate discontinuities, indicating criticality as the parameters cross from the first family of patterns to the second.

What's Wrong with Human/Nonhuman Chimera Research?

Directory of Open Access Journals (Sweden)

Insoo Hyun

2016-08-01

Full Text Available The National Institutes of Health (NIH is poised to lift its funding moratorium on research involving chimeric human/nonhuman embryos, pending further consideration by an NIH steering committee. The kinds of ethical concerns that seem to underlie this research and chimera research more generally can be adequately addressed.

Application of Chimera Composite Grid Scheme to Ship Appendages

National Research Council Canada - National Science Library

Lin, Cheng-Wen

1995-01-01

.... The chimera scheme of grid generation uses a system of relatively simple grids. The grids each define a particular component of the overall geometry, making the initial grid generation much simpler...

Studies on the mechanism of stable graft--host tolerance in canine and human radiation chimeras

International Nuclear Information System (INIS)

Storb, R.; Tsoi, M.S.; Weiden, P.L.; Graham, T.C.; Thomas, E.D.

1976-01-01

In studies with dogs, marrow donors were immunized against their chimeras by repeated skin grafts which they rejected. Lymphocytes from chimeras and donors were tested for cell inhibition by exposure to skin fibroblasts from chimeras and donors. Results were not compatible with the concept that tolerance in radiation chimeras is maintained by serum-blocking factors. They provide circumstantial evidence against the possibility that the stable chimeric state is the result of the deletion of a close or inactivation of donor lymphocytes specifically responsive for host antigens. They are most consistent with the possibility that a suppressor-cell population is responsible for the maintenance of tolerance. Human recipients of marrow transplants were tested with the cell inhibition assay. Although the incidence of positive cell inhibition and blocking was somewhat higher than in the dog, results were not compatible with the concept that serum blocking is the sole mechanism for maintaining the stable chimeric state in human patients

Allogeneic radiation chimeras respond to TNP-modified donor and host targets

International Nuclear Information System (INIS)

Lattime, E.C.; Gershon, H.E.; Stutman, O.

1980-01-01

Tolerance to major histocompatibility antigens as well as the ability to mount a cytotoxic response to hapten-modified cells of bone marrow donor and host origin was studied in allogeneic radiation chimeras. Lethally irradiated (C57BL/6 x DBA/2)F1 hosts reconstituted with anti-Thy 1.2 + C-treated bone marrow from (C57BL/6 x CBA)F1 mice showed tolerance to the MHC antigens of the three parental strains as measured by MLC and CML assay. The chimeras responded normally to unrelated allogeneic cells. Chimeric animals generated a cytotoxic response to hapten-modified cells of both donor (CBA) and host (DBA/2) haplotypes, as well as to C57BL/6, demonstrating that tolerance to the hapten-presenting host haplotype is sufficient to allow a cytotoxic antihapten response, and that processing through a semiallogeneic host environment does not affect the ability to generate a response to hapten in conjunction with self-determinants. Chimeras failed to mount a cytotoxic response to hapten presented on nontolerated allogeneic spleen cells

Mechanisms of appearance of amplitude and phase chimera states in ensembles of nonlocally coupled chaotic systems

Science.gov (United States)

Bogomolov, Sergey A.; Slepnev, Andrei V.; Strelkova, Galina I.; Schöll, Eckehard; Anishchenko, Vadim S.

2017-02-01

We explore the bifurcation transition from coherence to incoherence in ensembles of nonlocally coupled chaotic systems. It is firstly shown that two types of chimera states, namely, amplitude and phase, can be found in a network of coupled logistic maps, while only amplitude chimera states can be observed in a ring of continuous-time chaotic systems. We reveal a bifurcation mechanism by analyzing the evolution of space-time profiles and the coupling function with varying coupling coefficient and formulate the necessary and sufficient conditions for realizing the chimera states in the ensembles.

Tolerance, immunocompetence, and secondary disease in fully allogeneic radiation chimeras

International Nuclear Information System (INIS)

Rayfield, L.S.; Brent, L.

1983-01-01

The aim of this study was to ascertain the extent to which secondary disease and mortality in fully allogeneic chimeras (C57BL leads to CBA) is caused (if at all) by a delayed graft-versus-host reaction. Adult CBA males were thymectomized, irradiated, and reconstituted with T-lymphocyte-depleted C57BL or CBA bone marrow cells (BMC), followed three weeks after irradiation by implantation under the kidney capsule of thymic lobes from C57BL or CBA fetal or adult donors. These mice were observed for the development of secondary disease for periods in excess of 250 days, and they were examined at 5 weeks or 4 months for T lymphocyte reactivity and tolerance to alloantigens, using the cell-mediated lympholysis assay (CML). The following results were obtained. First, removal of T lymphocytes with anti-Thy 1 antibody and complement from allogeneic bone marrow did not prevent wasting and eventual death, although it prolonged the lifespan of mice substantially. Second, T lymphocytes generated from bone marrow-derived precursor cells became tolerant of the histocompatibility antigens of the thymus donor strain but remained normally reactive to third-party antigens. Third, allogeneic radiation chimeras did not survive as well as animals reconstituted with syngeneic cells, even when they were demonstrably tolerant in CML. Fourth, C57BL BMC maturing in a CBA host equipped with a C57BL thymus graft did not become tolerant of host antigens, indicating that extra-thymic tolerance does not occur in fully allogeneic--as opposed to semiallogeneic--chimeras. It is argued that the function of B lymphocytes and/or accessory cells is impaired in fully allogeneic radiation chimeras, and that the mortality observed was directly related to the resulting immunodeficiency. The relevance of the results described in this paper to clinical bone marrow transplantation is discussed

La Chimera di Dino Campana e Altre Chimere

Directory of Open Access Journals (Sweden)

Lucia Wataghin

2008-08-01

Full Text Available O presente artigo contém considerações sobre resultados e problemáticas da reutilização de materiais da tradição literária em um dos mais celebrados poemas de Dino Campana, La Chimera.

Greengenes: Chimera-checked 16S rRNA gene database and workbenchcompatible in ARB

Energy Technology Data Exchange (ETDEWEB)

DeSantis, T.Z.; Hugenholtz, P.; Larsen, N.; Rojas, M.; Brodie,E.L; Keller, K.; Huber, T.; Dalevi, D.; Hu, P.; Andersen, G.L.

2006-02-01

A 16S rRNA gene database (http://greengenes.lbl.gov) addresses limitations of public repositories by providing chimera-screening, standard alignments and taxonomic classification using multiple published taxonomies. It was revealed that incongruent taxonomic nomenclature exists among curators even at the phylum-level. Putative chimeras were identified in 3% of environmental sequences and 0.2% of records derived from isolates. Environmental sequences were classified into 100 phylum-level lineages within the Archaea and Bacteria.

Chronic graft-versus-host disease in the rat radiation chimera: I. clinical features, hematology, histology, and immunopathology in long-term chimeras

Energy Technology Data Exchange (ETDEWEB)

Beschorner, W.E.; Tutschka, P.J.; Santos, G.W.

1982-04-01

The clinical features, pathology, and immunopathology of chronic graft-versus-host disease (GVHD) developing in the long-term rat radiation chimera are described. At 6 to 12 months post-transplant, the previously stable ACI/LEW chimeras developed patchy to diffuse severe hair loss and thickened skin folds, and had microscopic features resembling scleroderma, Sjogren's syndrome, and chronic hepatitis. Skin histology showed dermal inflammation and acanthosis with atrophy of the appendages, with progression to dermal sclerosis. The liver revealed chronic hepatitis with bile duct injury and proliferation and periportal piecemeal necrosis. The tongue had considerable submucosal inflammation, muscular necrosis, and atrophy and arteritis. The serous salivary glands, lacrimal glands, and bronchi had lymphocytic inflammation and injury to duct, acinar, and mucosal columnar epithelium. The thymus had lymphocyte depletion of the medulla with prominent epithelium. The spleen and lymph nodes had poorly developed germinal centers but increased numbers of plasma cells. IgM was observed along the basement membrane and around the basal cells of the skin and tongue and along the basement membrane of the bile ducts. IgM was present also in the arteries of the tongue. Immunoglobulins eluted from the skin, cross-reacted with the bile duct epithelium and usually with both ACI and Lewis skin. Increased titers of speckled antinuclear antibodies were present in the serum of rats with chronic (GVHD). Chronic GVHD in the long-term rat radiation chimera is very similar to human chronic GVHD and is a potentially excellent model for autoimmune disorders including scleroderma, Sjorgren's syndrome, and chronic hepatitis.

Chronic graft-versus-host disease in the rat radiation chimera: I. clinical features, hematology, histology, and immunopathology in long-term chimeras

International Nuclear Information System (INIS)

Beschorner, W.E.; Tutschka, P.J.; Santos, G.W.

1982-01-01

The clinical features, pathology, and immunopathology of chronic graft-versus-host disease (GVHD) developing in the long-term rat radiation chimera are described. At 6 to 12 months post-transplant, the previously stable ACI/LEW chimeras developed patchy to diffuse severe hair loss and thickened skin folds, and had microscopic features resembling scleroderma, Sjogren's syndrome, and chronic hepatitis. Skin histology showed dermal inflammation and acanthosis with atrophy of the appendages, with progression to dermal sclerosis. The liver revealed chronic hepatitis with bile duct injury and proliferation and periportal piecemeal necrosis. The tongue had considerable submucosal inflammation, muscular necrosis, and atrophy and arteritis. The serous salivary glands, lacrimal glands, and bronchi had lymphocytic inflammation and injury to duct, acinar, and mucosal columnar epithelium. The thymus had lymphocyte depletion of the medulla with prominent epithelium. The spleen and lymph nodes had poorly developed germinal centers but increased numbers of plasma cells. IgM was observed along the basement membrane and around the basal cells of the skin and tongue and along the basement membrane of the bile ducts. IgM was present also in the arteries of the tongue. Immunoglobulins eluted from the skin, cross-reacted with the bile duct epithelium and usually with both ACI and Lewis skin. Increased titers of speckled antinuclear antibodies were present in the serum of rats with chronic (GVHD). Chronic GVHD in the long-term rat radiation chimera is very similar to human chronic GVHD and is a potentially excellent model for autoimmune disorders including scleroderma, Sjorgren's syndrome, and chronic hepatitis

Navier-Stokes Computations of Sabot Discard Using Chimera Scheme

National Research Council Canada - National Science Library

Ferry, E

1997-01-01

.... Numerical flow field computations have been made for various orientations and locations of sabots using an unsteady, zonal Navier-Stokes code and the Chimera composite grid discretization technique at M = 4.0 and alpha = 0...

Chimera states in Gaussian coupled map lattices

Science.gov (United States)

Li, Xiao-Wen; Bi, Ran; Sun, Yue-Xiang; Zhang, Shuo; Song, Qian-Qian

2018-04-01

We study chimera states in one-dimensional and two-dimensional Gaussian coupled map lattices through simulations and experiments. Similar to the case of global coupling oscillators, individual lattices can be regarded as being controlled by a common mean field. A space-dependent order parameter is derived from a self-consistency condition in order to represent the collective state.

Production of somatic chimera chicks by injection of bone marrow cells into recipient blastoderms.

Science.gov (United States)

Heo, Young Tae; Lee, Sung Ho; Kim, Teoan; Kim, Nam Hyung; Lee, Hoon Taek

2012-01-01

Several types of cells, including blastoderm cells, primordial germ cells, and embryonic germ cells were injected into early-stage recipient embryos to produce chimera avians and to gain insights into cell development. However, a limited number of studies of avian adult stem cells have also been conducted. This study is, to the best of our knowledge, the first to evaluate chicken bone marrow cells' (chBMC) ability to differentiate into multiple cell lineages and capability to generate chimera chicks. We induced random differentiation of chBMCs in vitro and injected immunologically selected pluripotent cells in chBMCs into the blastoderms of recipient eggs. The multipotency of BMCs from the barred Plymouth rock (BPR) was confirmed via AP staining, RT-PCR, immunocytochemistry, and FACS using specific markers, such as Oct-4 and SSEA-1, 3 and 4. Isolated chBMCs were found to be able to induce in vitro differentiation to multiple cell lineages. Approximately 5,000 chBMCs were injected into the blastoderms of white leghorn (WL) recipients and proved able to contribute to the generation of somatic chimera chicks with a frequency of 2.7% (2 of 73). Confirmation of chimerism in hatched chicks was achieved via PCR analysis using D-loop-specific primers of BPR and WL. Our study demonstrated the successful production of chimera chicks using chBMC. Therefore, we propose that the use of adult chBMCs may constitute a new possible approach to the production of chimera poultry, and may provide helpful studies in avian developmental biology.

Chimera: construction of chimeric sequences for phylogenetic analysis

NARCIS (Netherlands)

Leunissen, J.A.M.

2003-01-01

Chimera allows the construction of chimeric protein or nucleic acid sequence files by concatenating sequences from two or more sequence files in PHYLIP formats. It allows the user to interactively select genes and species from the input files. The concatenated result is stored to one single output

Chimera States in Mechanical Oscillator Networks

OpenAIRE

Martens, Erik Andreas; Thutupalli, Shashi; Fourrière, Antoine; Hallatschek, Oskar

2013-01-01

The synchronization of coupled oscillators is a fascinating manifestation of self-organization that nature uses to orchestrate essential processes of life, such as the beating of the heart. Although it was long thought that synchrony and disorder were mutually exclusive steady states for a network of identical oscillators, numerous theoretical studies in recent years have revealed the intriguing possibility of “chimera states,” in which the symmetry of the oscillator population is broken into...

Using CHIMERA detector at LNS for gamma-particle coincidences

Directory of Open Access Journals (Sweden)

Cardella G.

2016-01-01

Full Text Available We have recently evaluated the quality of γ-ray angular distributions that can be extracted in particle-gamma coincidence measurements using the CHIMERA detector at LNS. γ-rays have been detected using the CsI(Tl detectors of the spherical part of the CHIMERA array. Very clean γ-rays angular distributions were extracted in reactions induced by different stable beams impinging on 12C thin targets. The results evidenced an effect of projectile spin flip on the γ-rays angular distributions. γ-particle coincidence measurements were also performed in reactions induced by neutron rich exotic beams produced through in-flight fragmentation at LNS. In recent experiments also the Farcos array was used to improve energy and angular resolution measurements of the detected charged particles. Results obtained with both stable and radioactive beams are reported.

Application of Chimera Grid Scheme to Combustor Flowfields at all Speeds

Science.gov (United States)

Yungster, Shaye; Chen, Kuo-Huey

1997-01-01

A CFD method for solving combustor flowfields at all speeds on complex configurations is presented. The approach is based on the ALLSPD-3D code which uses the compressible formulation of the flow equations including real gas effects, nonequilibrium chemistry and spray combustion. To facilitate the analysis of complex geometries, the chimera grid method is utilized. To the best of our knowledge, this is the first application of the chimera scheme to reacting flows. In order to evaluate the effectiveness of this numerical approach, several benchmark calculations of subsonic flows are presented. These include steady and unsteady flows, and bluff-body stabilized spray and premixed combustion flames.

Transfer of experimental allergic encephalomyelitis to bone marrow chimeras. Endothelial cells are not a restricting element

International Nuclear Information System (INIS)

Hinrichs, D.J.; Wegmann, K.W.; Dietsch, G.N.

1987-01-01

The adoptive transfer of clinical and histopathologic signs of experimental allergic encephalomyelitis (EAE) requires MHC compatibility between cell donor and cell recipient. The results of adoptive transfer studies using F1 to parent bone marrow chimeras as recipients of parental-derived BP-sensitive spleen cells indicate that this restriction is not expressed at the level of the endothelial cell but is confined to the cells of bone marrow derivation. Furthermore, these results indicate that the development of EAE is not dependent on the activity of MHC-restricted cytotoxic cells

Targeting nanodisks via a single chain variable antibody - Apolipoprotein chimera

International Nuclear Information System (INIS)

Iovannisci, David M.; Beckstead, Jennifer A.; Ryan, Robert O.

2009-01-01

Nanodisks (ND) are nanometer scale complexes of phospholipid and apolipoprotein that have been shown to function as drug delivery vehicles. ND harboring significant quantities of the antifungal agent, amphotericin B, or the bioactive isoprenoid, all trans retinoic acid, have been generated and characterized. As currently formulated, ND possess limited targeting capability. In this study, we constructed a single chain variable antibody (scFv).apolipoprotein chimera and assessed the ability of this fusion protein to form ND and recognize the antigen to which the scFv is directed. Data obtained revealed that α-vimentin scFv.apolipoprotein A-I is functional in ND formation and antigen recognition, opening the door to the use of such chimeras in targeting drug-enriched ND to specific tissues.

An integrin alpha4beta7•IgG heterodimeric chimera binds to MAdCAM-1 on high endothelial venules in gut-associated lymphoid tissue.

Science.gov (United States)

Hoshino, Hitomi; Kobayashi, Motohiro; Mitoma, Junya; Sato, Yoshiko; Fukuda, Minoru; Nakayama, Jun

2011-06-01

Lymphocyte homing is regulated by a multistep process mediated by sequential adhesive interactions between circulating lymphocytes and high endothelial venules (HEVs). In gut-associated lymphoid tissue (GALT), the initial interactive step, "tethering and rolling," is partly mediated by integrin α4β7 expressed on GALT-homing lymphocytes and its ligand MAdCAM-1, which is exclusively expressed on HEVs in GALT. To probe functional MAdCAM-1 in tissue sections, we developed a soluble integrin α4β7 heterodimeric IgG chimera by joining the extracellular region of mouse integrin α4 and β7 subunits to a human IgG Fc domain. Western blot analysis revealed that co-transfection of HEK 293T cells with expression vectors encoding integrin α4•IgG and β7•IgG results in the formation of α4β7•IgG heterodimeric chimeras. This complex preferentially binds to CHO cells expressing MAdCAM-1 and, to a lesser extent, to cells expressing VCAM-1, but not to cells expressing ICAM-1. Moreover, α4β7•IgG specifically binds to HEVs in GALT in situ in a divalent cation-dependent fashion and inhibits lymphocyte binding to HEVs in GALT. These findings indicate that α4β7•IgG can be used as a probe for functional MAdCAM-1 expressed on HEVs in GALT and could potentially serve as an anti-inflammatory drug inhibiting GALT-specific lymphocyte migration.

Insights into the Activity and Substrate Binding of Xylella fastidiosa Polygalacturonase by Modification of a Unique QMK Amino Acid Motif Using Protein Chimeras.

Science.gov (United States)

Warren, Jeremy G; Lincoln, James E; Kirkpatrick, Bruce C

2015-01-01

Polygalacturonases (EC 3.2.1.15) catalyze the random hydrolysis of 1, 4-alpha-D-galactosiduronic linkages in pectate and other galacturonans. Xylella fastidiosa possesses a single polygalacturonase gene, pglA (PD1485), and X. fastidiosa mutants deficient in the production of polygalacturonase are non-pathogenic and show a compromised ability to systemically infect grapevines. These results suggested that grapevines expressing sufficient amounts of an inhibitor of X. fastidiosa polygalacturonase might be protected from disease. Previous work in our laboratory and others have tried without success to produce soluble active X. fastidiosa polygalacturonase for use in inhibition assays. In this study, we created two enzymatically active X. fastidiosa / A. vitis polygalacturonase chimeras, AX1A and AX2A to explore the functionality of X. fastidiosa polygalacturonase in vitro. The AX1A chimera was constructed to specifically test if recombinant chimeric protein, produced in Escherichia coli, is soluble and if the X. fastidiosa polygalacturonase catalytic amino acids are able to hydrolyze polygalacturonic acid. The AX2A chimera was constructed to evaluate the ability of a unique QMK motif of X. fastidiosa polygalacturonase, most polygalacturonases have a R(I/L)K motif, to bind to and allow the hydrolysis of polygalacturonic acid. Furthermore, the AX2A chimera was also used to explore what effect modification of the QMK motif of X. fastidiosa polygalacturonase to a conserved RIK motif has on enzymatic activity. These experiments showed that both the AX1A and AX2A polygalacturonase chimeras were soluble and able to hydrolyze the polygalacturonic acid substrate. Additionally, the modification of the QMK motif to the conserved RIK motif eliminated hydrolytic activity, suggesting that the QMK motif is important for the activity of X. fastidiosa polygalacturonase. This result suggests X. fastidiosa polygalacturonase may preferentially hydrolyze a different pectic substrate or

Chimera states in multi-strain epidemic models with temporary immunity

Science.gov (United States)

Bauer, Larissa; Bassett, Jason; Hövel, Philipp; Kyrychko, Yuliya N.; Blyuss, Konstantin B.

2017-11-01

We investigate a time-delayed epidemic model for multi-strain diseases with temporary immunity. In the absence of cross-immunity between strains, dynamics of each individual strain exhibit emergence and annihilation of limit cycles due to a Hopf bifurcation of the endemic equilibrium, and a saddle-node bifurcation of limit cycles depending on the time delay associated with duration of temporary immunity. Effects of all-to-all and non-local coupling topologies are systematically investigated by means of numerical simulations, and they suggest that cross-immunity is able to induce a diverse range of complex dynamical behaviors and synchronization patterns, including discrete traveling waves, solitary states, and amplitude chimeras. Interestingly, chimera states are observed for narrower cross-immunity kernels, which can have profound implications for understanding the dynamics of multi-strain diseases.

Multi-dimensional simulations of core-collapse supernova explosions with CHIMERA

Science.gov (United States)

Messer, O. E. B.; Harris, J. A.; Hix, W. R.; Lentz, E. J.; Bruenn, S. W.; Mezzacappa, A.

2018-04-01

Unraveling the core-collapse supernova (CCSN) mechanism is a problem that remains essentially unsolved despite more than four decades of effort. Spherically symmetric models with otherwise high physical fidelity generally fail to produce explosions, and it is widely accepted that CCSNe are inherently multi-dimensional. Progress in realistic modeling has occurred recently through the availability of petascale platforms and the increasing sophistication of supernova codes. We will discuss our most recent work on understanding neutrino-driven CCSN explosions employing multi-dimensional neutrino-radiation hydrodynamics simulations with the Chimera code. We discuss the inputs and resulting outputs from these simulations, the role of neutrino radiation transport, and the importance of multi-dimensional fluid flows in shaping the explosions. We also highlight the production of 48Ca in long-running Chimera simulations.

Polyfunctional analysis of Gag and Nef specific CD8+ T-cell responses in HIV-1 infected Indian individuals.

Science.gov (United States)

Mendiratta, Sanjay; Vajpayee, Madhu; Mojumdar, Kamalika; Chauhan, Neeraj K; Sreenivas, Vishnubhatla

2011-02-01

Polyfunctional CD8+ T-cells have been described as most competent in controlling viral replication. We studied the impact of antigen persistence on the polyfunctional immune responses of CD8+ T-lymphocytes to HIV Gag and Nef peptides and polyclonal stimuli in 40 ART naïve HIV infected individuals and analyzed the alterations in T-cell functionality in early and late stages of infection. Significantly elevated level of global response and polyfunctional profile of CD8+ T-cells were observed to polyclonal stimulation, than HIV specific antigens in chronically infected individuals. However no key differences were observed in CD8+ T-cell functional profile in any of the 15 unique subsets for Gag and Nef specific antigens. The subjects in early stage of infection (defined as a gap of 6 months or less between seroconversion and enrolment and with no apparent clinical symptoms) had a higher degree of response functionality (4+ or 3+ different functions simultaneously) than in the late stage infection (defined as time duration since seroconversion greater than 6 months). The data suggest that persistence of antigen during chronic infection leads to functional impairment of HIV specific responses. Copyright © 2010 Elsevier Ltd. All rights reserved.

Proteomic Analysis Reveals the Leaf Color Regulation Mechanism in Chimera Hosta "Gold Standard" Leaves.

Science.gov (United States)

Yu, Juanjuan; Zhang, Jinzheng; Zhao, Qi; Liu, Yuelu; Chen, Sixue; Guo, Hongliang; Shi, Lei; Dai, Shaojun

2016-03-08

Leaf color change of variegated leaves from chimera species is regulated by fine-tuned molecular mechanisms. Hosta "Gold Standard" is a typical chimera Hosta species with golden-green variegated leaves, which is an ideal material to investigate the molecular mechanisms of leaf variegation. In this study, the margin and center regions of young and mature leaves from Hosta "Gold Standard", as well as the leaves from plants after excess nitrogen fertilization were studied using physiological and comparative proteomic approaches. We identified 31 differentially expressed proteins in various regions and development stages of variegated leaves. Some of them may be related to the leaf color regulation in Hosta "Gold Standard". For example, cytosolic glutamine synthetase (GS1), heat shock protein 70 (Hsp70), and chloroplastic elongation factor G (cpEF-G) were involved in pigment-related nitrogen synthesis as well as protein synthesis and processing. By integrating the proteomics data with physiological results, we revealed the metabolic patterns of nitrogen metabolism, photosynthesis, energy supply, as well as chloroplast protein synthesis, import and processing in various leaf regions at different development stages. Additionally, chloroplast-localized proteoforms involved in nitrogen metabolism, photosynthesis and protein processing implied that post-translational modifications were crucial for leaf color regulation. These results provide new clues toward understanding the mechanisms of leaf color regulation in variegated leaves.

Construction of an Aptamer-SiRNA Chimera-Modified Tissue-Engineered Blood Vessel for Cell-Type-Specific Capture and Delivery.

Science.gov (United States)

Chen, Wen; Zeng, Wen; Sun, Jiansen; Yang, Mingcan; Li, Li; Zhou, Jingting; Wu, Yangxiao; Sun, Jun; Liu, Ge; Tang, Rui; Tan, Ju; Zhu, Chuhong

2015-06-23

The application of tissue-engineered blood vessels (TEBVs) is the main developmental direction of vascular replacement therapy. Due to few and/or dysfunctional endothelial progenitor cells (EPCs), it is difficult to successfully construct EPC capture TEBVs in diabetes. RNA has a potential application in cell protection and diabetes treatment, but poor specificity and low efficiency of RNA transfection in vivo limit the application of RNA. On the basis of an acellular vascular matrix, we propose an aptamer-siRNA chimera-modified TEBV that can maintain a satisfactory patency in diabetes. This TEBV consists of two parts, CD133-adenosine kinase (ADK) chimeras and a TEBV scaffold. Our results showed that CD133-ADK chimeras could selectively capture the CD133-positive cells in vivo, and then captured cells can internalize the bound chimeras to achieve RNA self-transfection. Subsequently, CD133-ADK chimeras were cut into ADK siRNA by a dicer, resulting in depletion of ADK. An ADK-deficient cell may act as a bioreactor that sustainably releases adenosine. To reduce nonspecific RNA transfection, we increased the proportion of HAuCl4 during the material preparation, through which the transfection capacity of polyethylenimine (PEI)/polyethylene glycol (PEG)-capped gold nanoparticles (PEI/PEG-AuNPs) was significantly decreased and the ability of TEBV to resist tensile and liquid shear stress was greatly enhanced. PEG and 2'-O-methyl modification was used to enhance the in vivo stability of RNA chimeras. At day 30 postgrafting, the patency rate of CD133-ADK chimera-modified TEBVs reached 90% in diabetic rats and good endothelialization was observed.

Radiobiological researches on Dianthus caryophyllus L. carnation chimeras

International Nuclear Information System (INIS)

Pereau-Leroy, Pierre

1975-01-01

This research thesis reports a radiobiological study of Dianthus periclinal chimeras performed by submitting plants and plant cuttings at different physiological stages to cobalt-60 gamma irradiation under different dose conditions and rates. The effects of these treatments are studied while growing the so-processed plants and by microscopic examination of sections of irradiated meristems [fr

Sequential analysis of the virus-immune responder characteristics of thymocytes from F1→parent radiation chimeras

International Nuclear Information System (INIS)

Korngold, R.; Doherty, P.C.

1982-01-01

The virus-immune responder characteristics of thymocytes, spleen and lymph node (LN) cells from (P 1 x P 2 )F 1 →P 1 radiation chimeras have been examined sequentially at weekly intervals. Adoptively-transferred thymocytes generate strong cytotoxic thymus-derived lymphocyte (CTL) responses from 28 to 100 days after reconstitution with bone marrow, which are almost invariably restricted to recognition of virus presented in the context of P 1 . This pattern of H-2 restriction is also maintained for spleen and LN cells from the [(H-2sup(kxd)F 1 →H-2sup(k)] and [(H-2sup(kxb)F 1 →H-2sup(k)] combinations but there is random emergence of reactivity to H-2sup(k)+virus for peripheral lymphoid cells from [(H-2sup(kxb)F 1 →H-2sup(b)] chimeras. Treatment of established [(P 1 xP 2 )]F 1 →P 1 ] chimeras with a low dose of cyclophosphamide (Cy) did not lead to the emergence of significant CTL effector function for P2 + virus. Also, administration of a large dose of Cy prior to irradiation of the chimera recipients did not modify the H-2 restriction profile of the chimera, though the level of CTL responsiveness associated with the appropriate H-2 type was apparently enhanced. (Auth.)

In vitro induction of mutation and separation of chimeras in Gerbera jamesonii

International Nuclear Information System (INIS)

Jerzy, M.; Zalewska, M.; Garczewska, A.

1994-01-01

Using ex vitro leaves as objects to be irradiated and to induce variation in sixteen Gerbera jamesonii cultivars, reproduced from adventitious buds, resulted in obtaining the mutants which inflorescence color was uniformly changed and which newly acquired traits recurred in the second generation of plants reproduced vegetatively from the isolated shoot tips. However, chimeras appeared among the vM 1 plants exposed to various doses of gamma rays (5-25 Gy and they constituted almost half of the mutated plants. A further propagation of chimeras from leaf explants forming adventitious shoots significantly increased the number of solid mutants with uniformly changed inflorescence color in the vM 1 generation. (author)

Chaos in Dirac Electron Optics: Emergence of a Relativistic Quantum Chimera.

Science.gov (United States)

Xu, Hong-Ya; Wang, Guang-Lei; Huang, Liang; Lai, Ying-Cheng

2018-03-23

We uncover a remarkable quantum scattering phenomenon in two-dimensional Dirac material systems where the manifestations of both classically integrable and chaotic dynamics emerge simultaneously and are electrically controllable. The distinct relativistic quantum fingerprints associated with different electron spin states are due to a physical mechanism analogous to a chiroptical effect in the presence of degeneracy breaking. The phenomenon mimics a chimera state in classical complex dynamical systems but here in a relativistic quantum setting-henceforth the term "Dirac quantum chimera," associated with which are physical phenomena with potentially significant applications such as enhancement of spin polarization, unusual coexisting quasibound states for distinct spin configurations, and spin selective caustics. Experimental observations of these phenomena are possible through, e.g., optical realizations of ballistic Dirac fermion systems.

Chaos in Dirac Electron Optics: Emergence of a Relativistic Quantum Chimera

Science.gov (United States)

Xu, Hong-Ya; Wang, Guang-Lei; Huang, Liang; Lai, Ying-Cheng

2018-03-01

We uncover a remarkable quantum scattering phenomenon in two-dimensional Dirac material systems where the manifestations of both classically integrable and chaotic dynamics emerge simultaneously and are electrically controllable. The distinct relativistic quantum fingerprints associated with different electron spin states are due to a physical mechanism analogous to a chiroptical effect in the presence of degeneracy breaking. The phenomenon mimics a chimera state in classical complex dynamical systems but here in a relativistic quantum setting—henceforth the term "Dirac quantum chimera," associated with which are physical phenomena with potentially significant applications such as enhancement of spin polarization, unusual coexisting quasibound states for distinct spin configurations, and spin selective caustics. Experimental observations of these phenomena are possible through, e.g., optical realizations of ballistic Dirac fermion systems.

Book Review: Evolution's Chimera: Bats and the Marvel of ...

African Journals Online (AJOL)

Abstract. Book Title: Evolution's Chimera: Bats and the Marvel of Evolutionary Adaptation. Book Author: David Jacobs. 2016, University of Cape Town Press, Juta and Company (Pty) Ltd, PO Box 14373, Lansdowne 7779, Cape Town, South Africa Softcover, 204 pages. ISBN 978-1-77582-212-7. Price R299 ...

Use of fragmentation beams at LNS with CHIMERA detector

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Gianí R.

2012-07-01

Full Text Available The recent intensity upgrade of the LNS fragmentation beam is discussed. The available beams, the tagging procedures and details on the beam quality are reported. The experimental program started with the CHIMERA detector using such beams is also discussed with preliminary results and future perspectives.

Chronic graft-versus-host disease in the rat radiation chimera. III. Immunology and immunopathology in rapidly induced models

International Nuclear Information System (INIS)

Beschorner, W.E.; Tutschka, P.J.; Santos, G.W.

1983-01-01

Although chronic graft-versus-host disease (GVHD) frequently develops in the long-term rat radiation chimera, we present three additional models in which a histologically similar disease is rapidly induced. These include adoptive transfer of spleen and bone marrow from rats with spontaneous chronic GVHD into lethally irradiated rats of the primary host strain; sublethal irradiation of stable chimeras followed by a booster transplant; and transfer of spleen cells of chimeras recovering from acute GVHD into second-party (primary recipient strain) or third-party hosts. Some immunopathologic and immune abnormalities associated with spontaneous chronic GVHD were not observed in one or more of the induced models. Thus, IgM deposition in the skin, antinuclear antibodies, and vasculitis appear to be paraphenomena. On the other hand, lymphoid hypocellularity of the thymic medulla, immaturity of splenic follicles, and nonspecific suppressor cells were consistently present in the long term chimeras, and in all models. These abnormalities therefore may be pathogenetically important, or closely related to the development of chronic GVHD

Functional clonal deletion versus suppressor cell-induced transplantation tolerance in chimeras prepared with a short course of total-lymphoid irradiation

International Nuclear Information System (INIS)

Slavin, S.; Morecki, S.; Weigensberg, M.; Bar, S.; Weiss, L.

1986-01-01

Allogeneic bone marrow (BM) chimeras induced by infusion of BM cells into recipients conditioned with total lymphoid irradiation (TLI) were shown to develop humoral and cell-mediated tolerance to host and donor-type alloantigens by a number of in vitro and in vivo assays. Spleen cells of tolerant chimeras exhibited suppressive activity of mixed lymphocyte reaction (MLR). MLR suppression was not abrogated by depletion of Lyt-2 cells, and neither could Lyt-2-positive cells sorted from the spleens of tolerant chimeras suppress MLR or attenuate graft-versus-host reactivity in vivo. Likewise, specifically unresponsive spleen cells obtained from chimeras could not be induced to respond in MLR against tolerizing host-type cells following depletion of Lyt-2 or passage through a nylon-wool column. Tolerance of chimera spleen cells to host alloantigens, best documented by permanent survival of donor-type skin allografts, could be adoptively transferred into syngeneic recipients treated by heavy irradiation but not into untreated or mildly irradiated recipients. Adoptive transfer of tolerance seemed to be associated with experimental conditions favoring engraftment of tolerant cells rather than suppression of host reactivity. We speculate that although host and/or donor-derived suppressor cells may be operating in reducing the pool of specific alloreactive clones by blocking cell proliferation in response to allogeneic challenge, the final outcome in tolerant chimeras is actual or functional deletion of alloreactive clones

Cysteine 138 mutation in HIV-1 Nef from patients with delayed disease progression

DEFF Research Database (Denmark)

Tolstrup, Martin; Laursen, Alex Lund; Gerstoft, J.

2006-01-01

on the delayed disease status. However, the results demonstrate a high incidence of a single amino acid polymorphism (cysteine 138) in HIV-1 Nef. The allelic frequency of cysteine 138 between the delayed disease progression group and the progressor group was found to be statistically significant (P = 0.......0139). The phylogeny of isolates was investigated and the variants harbouring the cysteine 138 mutation clustered independently. CONCLUSION: The present study describes a viral genetic polymorphism related to AIDS disease progression. The polymorphism (cysteine 138) has previously been reported to confer decreased...... viral replication (Premkumar DR, et al. AIDS Res Hum Retroviruses 1996; 12(4): 337-45). A sequence database search for comparative mutations revealed a high frequency of cysteine 138 in patients with reported SP AIDS...

Interspecies chimera between primate embryonic stem cells and mouse embryos: monkey ESCs engraft into mouse embryos, but not post-implantation fetuses.

Science.gov (United States)

Simerly, Calvin; McFarland, Dave; Castro, Carlos; Lin, Chih-Cheng; Redinger, Carrie; Jacoby, Ethan; Mich-Basso, Jocelyn; Orwig, Kyle; Mills, Parker; Ahrens, Eric; Navara, Chris; Schatten, Gerald

2011-07-01

Unequivocal evidence for pluripotency in which embryonic stem cells contribute to chimeric offspring has yet to be demonstrated in human or nonhuman primates (NHPs). Here, rhesus and baboons ESCs were investigated in interspecific mouse chimera generated by aggregation or blastocyst injection. Aggregation chimera produced mouse blastocysts with GFP-nhpESCs at the inner cell mass (ICM), and embryo transfers (ETs) generated dimly-fluorescencing abnormal fetuses. Direct injection of GFP-nhpESCs into blastocysts produced normal non-GFP-fluorescencing fetuses. Injected chimera showed >70% loss of GFP-nhpESCs after 21 h culture. Outgrowths of all chimeric blastocysts established distinct but separate mouse- and NHP-ESC colonies. Extensive endogenous autofluorescence compromised anti-GFP detection and PCR analysis did not detect nhpESCs in fetuses. NhpESCs localize to the ICM in chimera and generate pregnancies. Because primate ESCs do not engraft post-implantation, and also because endogenous autofluorescence results in misleading positive signals, interspecific chimera assays for pluripotency with primate stem cells is unreliable with the currently available ESCs. Testing primate ESCs reprogrammed into even more naïve states in these inter-specific chimera assays will be an important future endeavor. Copyright © 2011 Elsevier B.V. All rights reserved.

Solvable model of spiral wave chimeras.

Science.gov (United States)

Martens, Erik A; Laing, Carlo R; Strogatz, Steven H

2010-01-29

Spiral waves are ubiquitous in two-dimensional systems of chemical or biological oscillators coupled locally by diffusion. At the center of such spirals is a phase singularity, a topological defect where the oscillator amplitude drops to zero. But if the coupling is nonlocal, a new kind of spiral can occur, with a circular core consisting of desynchronized oscillators running at full amplitude. Here, we provide the first analytical description of such a spiral wave chimera and use perturbation theory to calculate its rotation speed and the size of its incoherent core.

Solvable Model of Spiral Wave Chimeras

DEFF Research Database (Denmark)

Martens, Erik Andreas; Laing, Carlo R.; Strogatz, Steven H.

2010-01-01

Spiral waves are ubiquitous in two-dimensional systems of chemical or biological oscillators coupled locally by diffusion. At the center of such spirals is a phase singularity, a topological defect where the oscillator amplitude drops to zero. But if the coupling is nonlocal, a new kind of spiral...... can occur, with a circular core consisting of desynchronized oscillators running at full amplitude. Here, we provide the first analytical description of such a spiral wave chimera and use perturbation theory to calculate its rotation speed and the size of its incoherent core....

Temporal intermittency and the lifetime of chimera states in ensembles of nonlocally coupled chaotic oscillators

Science.gov (United States)

Semenova, N. I.; Strelkova, G. I.; Anishchenko, V. S.; Zakharova, A.

2017-06-01

We describe numerical results for the dynamics of networks of nonlocally coupled chaotic maps. Switchings in time between amplitude and phase chimera states have been first established and studied. It has been shown that in autonomous ensembles, a nonstationary regime of switchings has a finite lifetime and represents a transient process towards a stationary regime of phase chimera. The lifetime of the nonstationary switching regime can be increased to infinity by applying short-term noise perturbations.

T cell receptor zeta allows stable expression of receptors containing the CD3gamma leucine-based receptor-sorting motif

DEFF Research Database (Denmark)

Dietrich, J; Geisler, C

1998-01-01

The leucine-based motif in the T cell receptor (TCR) subunit CD3gamma constitutes a strong internalization signal. In fully assembled TCR this motif is inactive unless phosphorylated. In contrast, the motif is constitutively active in CD4/CD3gamma and Tac/CD3gamma chimeras independently of phosph......The leucine-based motif in the T cell receptor (TCR) subunit CD3gamma constitutes a strong internalization signal. In fully assembled TCR this motif is inactive unless phosphorylated. In contrast, the motif is constitutively active in CD4/CD3gamma and Tac/CD3gamma chimeras independently...... of phosphorylation and leads to rapid internalization and sorting of these chimeras to lysosomal degradation. Because the TCRzeta chain rescues incomplete TCR complexes from lysosomal degradation and allows stable surface expression of fully assembled TCR, we addressed the question whether TCRzeta has the potential...... to mask the CD3gamma leucine-based motif. By studying CD4/CD3gamma and CD16/CD3gamma chimeras, we found that CD16/CD3gamma chimeras associated with TCRzeta. The CD16/CD3gamma-TCRzeta complexes were stably expressed at the cell surface and had a low spontaneous internalization rate, indicating...

Growth of transplantable melanoma and leukaemia and prevention of virus-induced leukaemia in long lived radiation chimeras constructed with unmanipulated bone marrow

International Nuclear Information System (INIS)

Pierpaoli, W.

1985-01-01

Haemopoietic radiation chimeras across the H-2 barrier (BALB/c → C57B1/6; H-2sup(d) → H-2sup(b) chimeras and vice versa) have been studied for their capacity to suppress the growth, or to reject, transplantable B16 melanotic melanoma and radiation leukaemia virus-induced, transplantable leukaemia. Also, radiation leukaemia virus (RadLV) obtained from the thymus of leukaemic C57B1/6 mice was injected i.p. into established chimeras (H-2sup(d) → H-2sup(b)). As expected, long lived, graft versus host disease free allogeneic chimeras constructed with intact bone marrow were unable to reject the tumours both when recipients were BALB/c → C57B1/6 or C57B1/6 → BALB/c chimeras. However, inoculation of a large number of immunocompetent cells from normal BALB/c mice into BALB/c → C57B1/6 chimeras failed to promote a rejection of the tumours. On the contrary, the same amount of syngeneic (BALB/c) immunocompetent cells prevented growth of melanoma when transferred into athymic nude BALB/c mice, while the tumour grew unimpaired in untreated athymic nude BALB/c mice. The same type of H-2sup(d) → H-2sup(b) chimeras displayed complete resistance to inoculation of leukaemogenic H-2sup(b) restricted RadLV while all H-2sup(b) → H-2sup(b), syngeneically reconstituted mice developed disseminated leukaemia. (author)

Analysis of the hormone-binding domain of steroid receptors using chimeras generated by homologous recombination

International Nuclear Information System (INIS)

Martinez, Elisabeth D.; Pattabiraman, Nagarajan; Danielsen, Mark

2005-01-01

The glucocorticoid receptor and the mineralocorticoid receptor are members of the steroid receptor family that exhibit ligand cross-reactivity. Specificity of steroid receptor action is investigated in the present work by the construction and characterization of chimeras between the glucocorticoid receptor and the mineralocorticoid receptor. We used an innovative approach to make novel steroid receptor proteins in vivo that in general, contrary to our expectations, show increased ligand specificity compared to the parental receptors. We describe a receptor that is specific for the potent synthetic glucocorticoid triamcinolone acetonide and does not bind aldosterone. A further set of chimeras has an increased ability to discriminate between ligands, responding potently to mineralocorticoids and only very weakly to synthetic glucocorticoids. A chimera with the fusion site in the hinge highlights the importance of the region between the DNA-binding and the hormone-binding domains since, unlike both the glucocorticoid and mineralocorticoid receptors, it only responds to mineralocorticoids. One chimera has reduced specificity in that it acts as a general corticoid receptor, responding to glucocorticoids and mineralocorticoids with similar potency and efficacy. Our data suggest that regions of the glucocorticoid and mineralocorticoid receptor hormone-binding domains are functionally non-reciprocal. We present transcriptional, hormone-binding, and structure-modeling evidence that suggests that receptor-specific interactions within and across domains mediate aspects of specificity in transcriptional responses to steroids

Studies on the mechanism of the self restriction of T cell responses in radiation chimeras

International Nuclear Information System (INIS)

Fink, P.J.; Bevan, M.J.

1981-01-01

Recent experiments with murine radiation chimeras have shown that F 1 T cells that mature in an H-2 homozygous thymus, as is the case in [F 1 → Parent 1] chimeras, are restricted to recognizing foreign antigen in the context of Parent 1 H-2 antigens. Conflicting results on the stringency of self H-2 restriction of T cells from normal mice have suggested that the thymic restriction in chimeras may be due to active suppression of parent 2-restricted T cell clones. We have therefore conducted 3 sets of experiments to test for suppression of maturing T cells that could mediate thymic tutoring of H-2-restriction specificity in chimeras. In 2 sets of experiments, we found no evidence that suppressor cells could be exported from 1 thymus and act either intrathymically on thymocytes in a 2nd thymus or extrathymically on recent thymic emigrants. We believe current data support a role for the thymus in positive as well as negative selection of maturing thymocytes on the basis of self recognition, in the absence of any suppression. Our results do not support the concept that suppression is responsible for the difference in the degree of self preference in the T cells of chimeric mice relative to cell populations obtained from neonatally tolerant mice or from normal mice after acute negative selection

EXAMINATION OF THE GERM CELL CHIMERA FORMING POTENTIAL OF MOUSE EMBRYONIC STEM CELLS

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V.B. CÂRSTEA

2007-05-01

Full Text Available The aim of this study was to examine the factors, which influence the chimeraforming potential of mouse embryonic stem cells (ES cells. In our work, we examinethe chimera producing ability of R1 and R1/E mouse ES cell lines. We found that thepassage number affects chimera-forming capability of the ES cells. With theincreasing of the passage number, it could be getting less chimera animal, and onlythe R1/E ES cell line derived cells could contribute to the germ cells. At first, wecompared the marker of pluripotency using immunostaining and RT PCR, but wecould not find any difference between the R1 and R1/E cell in this way. Atchromosome analysis, we found, that the number of aneuploid cells, in R1 ES cellline, dramatically increased after 10 passages. We thought that the reason is thatduring the cell division Y chromosome could not arrange correctly between the twonewly derived progeny cells. To prove our conception, we made X and YchromosomeFISH analyses. We found, that the aneuploid R1 and R1/E ES cellscontain only one X and one Y chromosome, so not the loss of Y chromosome causethe problem at the germ cell formation. At last, we made the karyotypeanalysis of R1 and R1/E ES cells at different passages. The karyotype analysisdemonstrated that in the case of R1 ES cell line, the 41 and 42-chromosomecontaining cells hold trisomy. With the increasing of the passages number, thenumber of trisomy containing aneuploid cells increased. The aneuploid ES cells cancontribute to the different tissuses of chimera animals, but cannot form viable germcells.

EXAMINATION OF THE GERM CELL CHIMERA FORMING POTENTIAL OF MOUSE EMBRYONIC STEM CELLS

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CÂRSTEA V. B

2007-01-01

Full Text Available The aim of this study was to examine the factors, which influence the chimeraforming potential of mouse embryonic stem cells (ES cells. In our work, we examinethe chimera producing ability of R1 and R1/E mouse ES cell lines. We found that thepassage number affects chimera-forming capability of the ES cells. With theincreasing of the passage number, it could be getting less chimera animal, and onlythe R1/E ES cell line derived cells could contribute to the germ cells. At first, wecompared the marker of pluripotency using immunostaining and RT PCR, but wecould not find any difference between the R1 and R1/E cell in this way. Atchromosome analysis, we found, that the number of aneuploid cells, in R1 ES cellline, dramatically increased after 10 passages. We thought that the reason is thatduring the cell division Y chromosome could not arrange correctly between the twonewly derived progeny cells. To prove our conception, we made X and YchromosomeFISH analyses. We found, that the aneuploid R1 and R1/E ES cellscontain only one X and one Y chromosome, so not the loss of Y chromosome causethe problem at the germ cell formation. At last, we made the karyotypeanalysis of R1 and R1/E ES cells at different passages. The karyotype analysisdemonstrated that in the case of R1 ES cell line, the 41 and 42-chromosomecontaining cells hold trisomy. With the increasing of the passages number, thenumber of trisomy containing aneuploid cells increased. The aneuploid ES cells cancontribute to the different tissuses of chimera animals, but cannot form viable germcells.

Chimera patterns in two-dimensional networks of coupled neurons

Science.gov (United States)

Schmidt, Alexander; Kasimatis, Theodoros; Hizanidis, Johanne; Provata, Astero; Hövel, Philipp

2017-03-01

We discuss synchronization patterns in networks of FitzHugh-Nagumo and leaky integrate-and-fire oscillators coupled in a two-dimensional toroidal geometry. A common feature between the two models is the presence of fast and slow dynamics, a typical characteristic of neurons. Earlier studies have demonstrated that both models when coupled nonlocally in one-dimensional ring networks produce chimera states for a large range of parameter values. In this study, we give evidence of a plethora of two-dimensional chimera patterns of various shapes, including spots, rings, stripes, and grids, observed in both models, as well as additional patterns found mainly in the FitzHugh-Nagumo system. Both systems exhibit multistability: For the same parameter values, different initial conditions give rise to different dynamical states. Transitions occur between various patterns when the parameters (coupling range, coupling strength, refractory period, and coupling phase) are varied. Many patterns observed in the two models follow similar rules. For example, the diameter of the rings grows linearly with the coupling radius.

Polariton Chimeras: Bose-Einstein Condensates with Intrinsic Chaoticity and Spontaneous Long-Range Ordering

Science.gov (United States)

Gavrilov, S. S.

2018-01-01

The system of cavity polaritons driven by a plane electromagnetic wave is found to undergo the spontaneous breaking of spatial symmetry, which results in a lifted phase locking with respect to the driving field and, consequently, in the possibility of internal ordering. In particular, periodic spin and intensity patterns arise in polariton wires; they exhibit strong long-range order and can serve as media for signal transmission. Such patterns have the properties of dynamical chimeras: they are formed spontaneously in perfectly homogeneous media and can be partially chaotic. The reported new mechanism of chimera formation requires neither time-delayed feedback loops nor nonlocal interactions.

Chimera grids in the simulation of three-dimensional flowfields in turbine-blade-coolant passages

Science.gov (United States)

Stephens, M. A.; Rimlinger, M. J.; Shih, T. I.-P.; Civinskas, K. C.

1993-01-01

When computing flows inside geometrically complex turbine-blade coolant passages, the structure of the grid system used can affect significantly the overall time and cost required to obtain solutions. This paper addresses this issue while evaluating and developing computational tools for the design and analysis of coolant-passages, and is divided into two parts. In the first part, the various types of structured and unstructured grids are compared in relation to their ability to provide solutions in a timely and cost-effective manner. This comparison shows that the overlapping structured grids, known as Chimera grids, can rival and in some instances exceed the cost-effectiveness of unstructured grids in terms of both the man hours needed to generate grids and the amount of computer memory and CPU time needed to obtain solutions. In the second part, a computational tool utilizing Chimera grids was used to compute the flow and heat transfer in two different turbine-blade coolant passages that contain baffles and numerous pin fins. These computations showed the versatility and flexibility offered by Chimera grids.

Human-animal chimera: a neuro driven discussion? Comparison of three leading European research countries.

Science.gov (United States)

Cabrera Trujillo, Laura Yenisa; Engel-Glatter, Sabrina

2015-06-01

Research with human-animal chimera raises a number of ethical concerns, especially when neural stem cells are transplanted into the brains of non-human primates (NHPs). Besides animal welfare concerns and ethical issues associated with the use of embryonic stem cells, the research is also regarded as controversial from the standpoint of NHPs developing cognitive or behavioural capabilities that are regarded as "unique" to humans. However, scientists are urging to test new therapeutic approaches for neurological diseases in primate models as they better mimic human physiology than all current animal models. As a response, various countries have issued reports on the topic. Our paper summarizes the ethical issues raised by research with human-animal brain chimeras and compares the relevant regulatory instruments and different recommendations issued in national reports from three important European research nations: Germany, Switzerland and the United Kingdom. We assess and discuss the focus and priorities set by the different reports, review various reasons for and perspectives on the importance of the brain in chimera research, and identify critical points in the reports that warrant further specification and debate.

Mechanism of donor to host tolerance in rat bone marrow chimeras

International Nuclear Information System (INIS)

Tutschka, P.; Schwerdtfeger, R.; Slavin, R.; Santos, G.

1977-01-01

Lewis rats were conditioned with cyclophosphamide and grafted with AgB incompatible bone marrow. They were examined 250 days after transplantation and demonstrated to be healthy complete chimeras. Marrow cells from these chimeras were infused into lethally irradiated ACI, Lewis and BN recipients. Graft-versus-host disease occurred only in the BN rats. Other chimeric rats were given no treatment, busulfan, CY, or total body irradiation prior to the infusion of normal ACI BM. GvHD occurred only in animals given CY or TBI. Normal Lewis rats were conditioned with TBI and given ACI BM. In addition, they received whole blood, irradiated blood, or serum from chimeric rats. GvHD developed in all animals except those given unirradiated chimeric blood. These studies suggest that suppressor cell populations, sensitive to immunosuppression, are likely the fundamental mechanism of recovery from GvHD

Induction of chlorophyll chimeras and chlorophyll mutations in mungbean (Vigna radiata) cv. T44

International Nuclear Information System (INIS)

Singh, V.P.; Yadav, R.D.S.

1993-01-01

Uniform and healthy seeds of mungbean (Vigna radiata) cv. T44 were exposed to varying doses of gamma rays, ethyl methane sulphonate (EMS) and combination treatment of gamma rays with EMS. The data were recorded for seed germination, plant survival, frequency and spectrum of chlorophyll chimeras in M 1 and chlorophyll mutations in M 2 generation. Among all, the combination treatments were found most effective for inducing chlorophyll chimeras and chlorophyll mutations than the gamma rays or EMS alone. Of the mutants under reference, the albino, xantha and chlorina showed monogenic recessive while viridis exhibited digenic recessive inheritance. (author). 8 refs., 2 tabs

Human Polycomb group EED protein negatively affects HIV-1 assembly and release

Directory of Open Access Journals (Sweden)

Darlix Jean-Luc

2007-06-01

Full Text Available Abstract Background The human EED protein, a member of the superfamily of Polycomb group (PcG proteins with WD-40 repeats, has been found to interact with three HIV-1 components, namely the structural Gag matrix protein (MA, the integrase enzyme (IN and the Nef protein. The aim of the present study was to analyze the possible biological role of EED in HIV-1 replication, using the HIV-1-based vector HIV-Luc and EED protein expressed by DNA transfection of 293T cells. Results During the early phase of HIV-1 infection, a slight negative effect on virus infectivity occurred in EED-expressing cells, which appeared to be dependent on EED-MA interaction. At late times post infection, EED caused an important reduction of virus production, from 20- to 25-fold as determined by CAp24 immunoassay, to 10- to 80-fold based on genomic RNA levels, and this decrease was not due to a reduction of Gag protein synthesis. Coexpression of WTNef, or the non-N-myristoylated mutant NefG2A, restored virus yields to levels obtained in the absence of exogenous EED protein. This effect was not observed with mutant NefΔ57 mimicking the Nef core, or with the lipid raft-retargeted fusion protein LAT-Nef. LATAA-Nef, a mutant defective in the lipid raft addressing function, had the same anti-EED effect as WTNef. Cell fractionation and confocal imaging showed that, in the absence of Nef, EED mainly localized in membrane domains different from the lipid rafts. Upon co-expression with WTNef, NefG2A or LATAA-Nef, but not with NefΔ57 or LAT-Nef, EED was found to relocate into an insoluble fraction along with Nef protein. Electron microscopy of HIV-Luc producer cells overexpressing EED showed significant less virus budding at the cell surface compared to control cells, and ectopic assembly and clustering of nuclear pore complexes within the cytoplasm. Conclusion Our data suggested that EED exerted an antiviral activity at the late stage of HIV-1 replication, which included genomic

Bacterial membrane activity of a-peptide/b-peptoid chimeras: Influence of amino acid composition and chain length on the activity against different bacterial strains

DEFF Research Database (Denmark)

Hein-Kristensen, Line; Knapp, Kolja M; Franzyk, Henrik

2011-01-01

and subsequent killing is usually not tested. In this report, six α-peptide/β-peptoid chimeras were examined for the effect of amino acid/peptoid substitutions and chain length on the membrane perturbation and subsequent killing of food-borne and clinical bacterial isolates. RESULTS: All six AMP analogues...... acid only had a minor effect on MIC values, whereas chain length had a profound influence on activity. All chimeras were less active against Serratia marcescens (MICs above 46 μM). The chimeras were bactericidal and induced leakage of ATP from Staphylococcus aureus and S. marcescens with similar time...... of onset and reduction in the number of viable cells. EDTA pre-treatment of S. marcescens and E. coli followed by treatment with chimeras resulted in pronounced killing indicating that disintegration of the Gram-negative outer membrane eliminated innate differences in susceptibility. Chimera chain length...

Serine integrase chimeras with activity in E. coli and HeLa cells

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Alfonso P. Farruggio

2014-09-01

Full Text Available In recent years, application of serine integrases for genomic engineering has increased in popularity. The factor-independence and unidirectionality of these large serine recombinases makes them well suited for reactions such as site-directed vector integration and cassette exchange in a wide variety of organisms. In order to generate information that might be useful for altering the specificity of serine integrases and to improve their efficiency, we tested a hybridization strategy that has been successful with several small serine recombinases. We created chimeras derived from three characterized members of the serine integrase family, phiC31, phiBT1, and TG1 integrases, by joining their amino- and carboxy-terminal portions. We found that several phiBT1-phiC31 (BC and phiC31-TG1 (CT hybrid integrases are active in E. coli. BC chimeras function on native att-sites and on att-sites that are hybrids between those of the two donor enzymes, while CT chimeras only act on the latter att-sites. A BC hybrid, BC{−1}, was also active in human HeLa cells. Our work is the first to demonstrate chimeric serine integrase activity. This analysis sheds light on integrase structure and function, and establishes a potentially tractable means to probe the specificity of the thousands of putative large serine recombinases that have been revealed by bioinformatics studies.

Restricted antibody formation to sheep erythrocytes of allogeneic bone marrow chimeras histoincompatible at the K end of the H-2 complex

International Nuclear Information System (INIS)

Onoe, K.; Yasumizu, R.; Oh-Ishi, T.; Kakinuma, M.; Good, R.A.; Morikawa, K.

1981-01-01

Employing a new method for allogeneic bone marrow transplantation, irradiation chimeras constructed from various combinations of marrow cells from B10 H-2 recombinant mice and AKR recipients were prepared. Though these chimeras had well-developed populations of T and B cells, they showed strikingly different patterns of responses in the primary antibody formation to sheep erythrocytes (SRBC), a T dependent antigen. These are (a) AKR mice treated with C57BL/10 cells, [B10 leads to AKR] fully H-2 incompatible, and AKR mice treated with B10.A (5R) cells, [5R leads to AKR] I-J,E compatible chimeras that were almost completely unresponsive to SRBC; (b) AKR mice treated with B10.BR cells [BR leads to AKR] fully H-2 compatible, and AKR mice treated with B10 AKM cells, [AKM leads to AKR] chimeras where donor and recipient differed only at H-2D, showed the same number of plaque-forming cells (PFC) as B10 control mice; (c) AKR mice treated with B10.A cells, [B10 leads to AKR] chimeras, where donor and recipient were matched at H-2K-I-E region, showed about one-half the number of PFC as the control mice. From these results we conclude that in allogeneic bone marrow chimeras primary antibody response to T-dependent antigen, such as SRBC, is generated when at least the K end of the H-2 complex is compatible between donor and recipient

Resistance to BN myelogenous leukemia in rat radiation chimeras

International Nuclear Information System (INIS)

Singer, D.E.; Haynor, D.R.; Williams, R.M

1980-01-01

Lewis → LBNFl rat radiation chimeras showed marked resistance to transplanted BN myelogenous leukemia when compared to naive LBNFl, LBNFl → LBNFl, or BN → LBNFl. This occurred in the absence of overt graft versus host disease or of anti-BN response in mixed lymphocyte culture. Bone marrow specific antigens may serve as the target of the resistance mechanism. (author)

Numerical and analytical investigation of the chimera state excitation conditions in the Kuramoto-Sakaguchi oscillator network

Science.gov (United States)

Frolov, Nikita S.; Goremyko, Mikhail V.; Makarov, Vladimir V.; Maksimenko, Vladimir A.; Hramov, Alexander E.

2017-03-01

In this paper we study the conditions of chimera states excitation in ensemble of non-locally coupled Kuramoto-Sakaguchi (KS) oscillators. In the framework of current research we analyze the dynamics of the homogeneous network containing identical oscillators. We show the chimera state formation process is sensitive to the parameters of coupling kernel and to the KS network initial state. To perform the analysis we have used the Ott-Antonsen (OA) ansatz to consider the behavior of infinitely large KS network.

The contribution of human/non-human animal chimeras to stem cell research

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Sonya Levine

2017-10-01

Full Text Available Chimeric animals are made up of cells from two separate zygotes. Human/non-human animal chimeras have been used for a number of research purposes, including human disease modeling. Pluripotent stem cell (PSC research has relied upon the chimera approach to examine the developmental potential of stem cells, to determine the efficacy of cell replacement therapies, and to establish a means of producing human organs. Based on ethical issues, this work has faced pushback from various sources including funding agencies. We discuss here the essential role these studies have played, from gaining a better understanding of human biology to providing a stepping stone to human disease treatments. We also consider the major ethical issues, as well as the current status of support for this work in the United States.

Efficient expression of functional (α6β22β3 AChRs in Xenopus oocytes from free subunits using slightly modified α6 subunits.

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Carson Kai-Kwong Ley

Full Text Available Human (α6β2(α4β2β3 nicotinic acetylcholine receptors (AChRs are essential for addiction to nicotine and a target for drug development for smoking cessation. Expressing this complex AChR is difficult, but has been achieved using subunit concatamers. In order to determine what limits expression of α6* AChRs and to efficiently express α6* AChRs using free subunits, we investigated expression of the simpler (α6β22β3 AChR. The concatameric form of this AChR assembles well, but is transported to the cell surface inefficiently. Various chimeras of α6 with the closely related α3 subunit increased expression efficiency with free subunits and produced pharmacologically equivalent functional AChRs. A chimera in which the large cytoplasmic domain of α6 was replaced with that of α3 increased assembly with β2 subunits and transport of AChRs to the oocyte surface. Another chimera replacing the unique methionine 211 of α6 with leucine found at this position in transmembrane domain 1 of α3 and other α subunits increased assembly of mature subunits containing β3 subunits within oocytes. Combining both α3 sequences in an α6 chimera increased expression of functional (α6β22β3 AChRs to 12-fold more than with concatamers. This is pragmatically useful, and provides insights on features of α6 subunit structure that limit its expression in transfected cells.

Chimera states in brain networks: Empirical neural vs. modular fractal connectivity

Science.gov (United States)

Chouzouris, Teresa; Omelchenko, Iryna; Zakharova, Anna; Hlinka, Jaroslav; Jiruska, Premysl; Schöll, Eckehard

2018-04-01

Complex spatiotemporal patterns, called chimera states, consist of coexisting coherent and incoherent domains and can be observed in networks of coupled oscillators. The interplay of synchrony and asynchrony in complex brain networks is an important aspect in studies of both the brain function and disease. We analyse the collective dynamics of FitzHugh-Nagumo neurons in complex networks motivated by its potential application to epileptology and epilepsy surgery. We compare two topologies: an empirical structural neural connectivity derived from diffusion-weighted magnetic resonance imaging and a mathematically constructed network with modular fractal connectivity. We analyse the properties of chimeras and partially synchronized states and obtain regions of their stability in the parameter planes. Furthermore, we qualitatively simulate the dynamics of epileptic seizures and study the influence of the removal of nodes on the network synchronizability, which can be useful for applications to epileptic surgery.

Acute serum amyloid A induces migration, angiogenesis, and inflammation in synovial cells in vitro and in a human rheumatoid arthritis/SCID mouse chimera model.

LENUS (Irish Health Repository)

Connolly, Mary

2010-06-01

Serum amyloid A (A-SAA), an acute-phase protein with cytokine-like properties, is expressed at sites of inflammation. This study investigated the effects of A-SAA on chemokine-regulated migration and angiogenesis using rheumatoid arthritis (RA) cells and whole-tissue explants in vitro, ex vivo, and in vivo. A-SAA levels were measured by real-time PCR and ELISA. IL-8 and MCP-1 expression was examined in RA synovial fibroblasts, human microvascular endothelial cells, and RA synovial explants by ELISA. Neutrophil transendothelial cell migration, cell adhesion, invasion, and migration were examined using transwell leukocyte\\/monocyte migration assays, invasion assays, and adhesion assays with or without anti-MCP-1\\/anti-IL-8. NF-kappaB was examined using a specific inhibitor and Western blotting. An RA synovial\\/SCID mouse chimera model was used to examine the effects of A-SAA on cell migration, proliferation, and angiogenesis in vivo. High expression of A-SAA was demonstrated in RA patients (p < 0.05). A-SAA induced chemokine expression in a time- and dose-dependent manner (p < 0.05). Blockade with anti-scavenger receptor class B member 1 and lipoxin A4 (A-SAA receptors) significantly reduced chemokine expression in RA synovial tissue explants (p < 0.05). A-SAA induced cell invasion, neutrophil-transendothelial cell migration, monocyte migration, and adhesion (all p < 0.05), effects that were blocked by anti-IL-8 or anti-MCP-1. A-SAA-induced chemokine expression was mediated through NF-kappaB in RA explants (p < 0.05). Finally, in the RA synovial\\/SCID mouse chimera model, we demonstrated for the first time in vivo that A-SAA directly induces monocyte migration from the murine circulation into RA synovial grafts, synovial cell proliferation, and angiogenesis (p < 0.05). A-SAA promotes cell migrational mechanisms and angiogenesis critical to RA pathogenesis.

Cysteine 138 mutation in HIV-1 Nef from patients with delayed disease progression

DEFF Research Database (Denmark)

Tolstrup, Martin; Laursen, Alex Lund; Gerstoft, J.

2006-01-01

.0139). The phylogeny of isolates was investigated and the variants harbouring the cysteine 138 mutation clustered independently. CONCLUSION: The present study describes a viral genetic polymorphism related to AIDS disease progression. The polymorphism (cysteine 138) has previously been reported to confer decreased......-1 isolates from patients in a long-term non-progressor (LTNP) cohort and a slow-progressor (SP) cohort (n = 11) was analysed and compared with isolates from a control patient group of progressors (n = 18). Most of the patients with delayed disease progression had extensive medical records, providing...... an insight into the LTNP disease profile and allowing for the stratification of patients based on their CD4 cell decline. RESULTS: In sequences from nine patients, most of the functional domains of HIV-1 Nef appeared intact, and no major deletions were observed to possibly account for an effect...

A 3-D chimera grid embedding technique

Science.gov (United States)

Benek, J. A.; Buning, P. G.; Steger, J. L.

1985-01-01

A three-dimensional (3-D) chimera grid-embedding technique is described. The technique simplifies the construction of computational grids about complex geometries. The method subdivides the physical domain into regions which can accommodate easily generated grids. Communication among the grids is accomplished by interpolation of the dependent variables at grid boundaries. The procedures for constructing the composite mesh and the associated data structures are described. The method is demonstrated by solution of the Euler equations for the transonic flow about a wing/body, wing/body/tail, and a configuration of three ellipsoidal bodies.

Stable Chimeras and Independently Synchronizable Clusters

Science.gov (United States)

Cho, Young Sul; Nishikawa, Takashi; Motter, Adilson E.

2017-08-01

Cluster synchronization is a phenomenon in which a network self-organizes into a pattern of synchronized sets. It has been shown that diverse patterns of stable cluster synchronization can be captured by symmetries of the network. Here, we establish a theoretical basis to divide an arbitrary pattern of symmetry clusters into independently synchronizable cluster sets, in which the synchronization stability of the individual clusters in each set is decoupled from that in all the other sets. Using this framework, we suggest a new approach to find permanently stable chimera states by capturing two or more symmetry clusters—at least one stable and one unstable—that compose the entire fully symmetric network.

Cellular basis of the immunohematologic defects observed in short-term semiallogeneic B6C3F1→C3H chimeras: evidence for host-versus-graft reaction initiated by radioresistant T cells

International Nuclear Information System (INIS)

Aizawa, S.; Sado, T.; Kamisaku, H.; Kubo, E.

1980-01-01

Lethally irradiated C3Hf mice reconstituted with a relatively low dose (2 x 10 6 ) of B6C3F 1 bone marrow cells (B6C3F 1 →C3Hf chimeras) frequently manifest immunohematologic deficiencies during the first month following injection of bone marrow cells. They show slow recovery of antibody-forming potential to sheep red blood cells (SRBC) as compared to that observed in syngeneic (C3Hf→C3Hf or B6C3F 1 →B6C3F 1 ) chimeras. They also show a deficiency of B-cell activity as assessed by antibody response to SRBC following further reconstitution with B6C3F 1 -derived thymus cells 1 week after injection of bone marrow cells. A significant fraction of B6C3F 1 →C3Hf chimeras was shown to manifest a sudden loss of cellularity of spleens during the second week following injection of bone marrow cells even though cellularity was restored to the normal level within 1 week. The splenic mononuclear cells recovered from such chimeras almost invariably showed strong cytotoxicity against target cells expressing donor-type specific H-2 antigens (H-2/sup b/) when assesed by 51 Cr-release assay in vitro. The effector cells responsible for the observed anti-donor specific cytotoxicity were shown to be residual host-derived T cells. These results indicate strongly that residual host T cells could develop anti-donor specific cytotoxicity even after exposure to a supralethal dose (1050 R) of radiation and that the immunohematologic disturbances observed in shortterm F 1 to parent bone marrow chimeras (B6C3F 1 →C3Hf) were due to host-versus-graft reaction (HVGR) initiated by residual host T cells. The implication of these findings on the radiobiological nature of the residual T cells and the persistence of potentially anti-donor reactive T-cell clones in long-surviving allogeneic bone marrow chimeras was discussed

Icing modelling in NSMB with chimera overset grids

Energy Technology Data Exchange (ETDEWEB)

Pena, D. [Ècole Polytechnique de Montréal (Canada); ICUBE, Strasbourg University (France); Deloze, T.; Laurendeau, E. [Ècole Polytechnique de Montréal (Canada); Hoarau, Y. [ICUBE, Strasbourg University (France)

2015-03-10

In aerospace Engineering, the accurate simulation of ice accretion is a key element to increase flight safety and avoid accidents related to icing effects. The icing code developed in the NSMB solver is based on an Eulerian formulation for droplets tracking, an iterative Messinger model using a modified water runback scheme for ice thickness calculation and mesh deformation to track the ice/air interface through time. The whole process is parallelized with MPI and applied with chimera grids.

The contribution of human/non-human animal chimeras to stem cell research.

Science.gov (United States)

Levine, Sonya; Grabel, Laura

2017-10-01

Chimeric animals are made up of cells from two separate zygotes. Human/non-human animal chimeras have been used for a number of research purposes, including human disease modeling. Pluripotent stem cell (PSC) research has relied upon the chimera approach to examine the developmental potential of stem cells, to determine the efficacy of cell replacement therapies, and to establish a means of producing human organs. Based on ethical issues, this work has faced pushback from various sources including funding agencies. We discuss here the essential role these studies have played, from gaining a better understanding of human biology to providing a stepping stone to human disease treatments. We also consider the major ethical issues, as well as the current status of support for this work in the United States. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Numerical solution of the full potential equation using a chimera grid approach

Science.gov (United States)

Holst, Terry L.

1995-01-01

A numerical scheme utilizing a chimera zonal grid approach for solving the full potential equation in two spatial dimensions is described. Within each grid zone a fully-implicit approximate factorization scheme is used to advance the solution one interaction. This is followed by the explicit advance of all common zonal grid boundaries using a bilinear interpolation of the velocity potential. The presentation is highlighted with numerical results simulating the flow about a two-dimensional, nonlifting, circular cylinder. For this problem, the flow domain is divided into two parts: an inner portion covered by a polar grid and an outer portion covered by a Cartesian grid. Both incompressible and compressible (transonic) flow solutions are included. Comparisons made with an analytic solution as well as single grid results indicate that the chimera zonal grid approach is a viable technique for solving the full potential equation.

HINTW, a W-chromosome HINT gene in chick, is expressed ubiquitously and is a robust female cell marker applicable in intraspecific chimera studies.

Science.gov (United States)

Nagai, Hiroki; Sezaki, Maiko; Bertocchini, Federica; Fukuda, Kimiko; Sheng, Guojun

2014-05-01

Grafting and transplantation experiments in embryology require proper distinction between host and donor tissues. For the avian model this has traditionally been achieved by using two closely related species (e.g., chick and quail) followed by species-specific antibody staining. Here, we show that an in situ hybridization probe against the HINTW gene is a robust and reliable marker for female-derived chicken cells. At all pre-circulation stages tested, all cells in female embryos, independently confirmed by PCR analysis, were strongly positive for HINTW, whereas all male embryos were negative. This probe is broadly applicable in intra-specific chick/chick chimera studies, and as a proof of principle, we utilized this probe to detect female cells in three experimental settings: (1) to mark female donor cells in a node transplantation assay; (2) to distinguish female cells in male/female twins generated by the Cornish pasty culture; and (3) to detect female half of the embryo in artificially generated bilateral gynandromorphs. A rapid, PCR based pre-screening step increases the efficiency of obtaining desired donor/host sex combination from 25% to 100%. For most avian chimera studies, this female-specific in situ probe is a low cost alternative to the commonly used QCPN antibody and to ubiquitous-GFP chicken strains which are not widely available to the research community. © 2014 Wiley Periodicals, Inc.

The ethics of killing human/great-ape chimeras for their organs: a reply to Shaw et al.

Science.gov (United States)

Palacios-González, César

2016-06-01

The aim of this paper is to critically examine David Shaw, Wybo Dondorp, and Guido de Wert's arguments in favour of the procurement of human organs from human/nonhuman-primate chimeras, specifically from great-ape/human chimeras. My main claim is that their arguments fail and are in need of substantial revision. To prove this I first introduce the topic, and then reconstruct Shaw et al.'s position and arguments. Next, I show that Shaw et al.: (1) failed to properly apply the subsidiarity and proportionality principles; (2) neglected species overlapping cases in their ethical assessment; (3) ignored the ethics literature on borderline persons; and (4) misunderstood McMahan's two-tiered moral theory. These mistakes render an important part of their conclusions either false or problematic to the point that they would no longer endorse them. Finally I will briefly mention a possible multipolar solution to the human organ shortage problem that would reduce the need for chimeras' organs.

Immunogenicity of seven new recombinant yellow fever viruses 17D expressing fragments of SIVmac239 Gag, Nef, and Vif in Indian rhesus macaques.

Directory of Open Access Journals (Sweden)

Mauricio A Martins

Full Text Available An effective vaccine remains the best solution to stop the spread of human immunodeficiency virus (HIV. Cellular immune responses have been repeatedly associated with control of viral replication and thus may be an important element of the immune response that must be evoked by an efficacious vaccine. Recombinant viral vectors can induce potent T-cell responses. Although several viral vectors have been developed to deliver HIV genes, only a few have been advanced for clinical trials. The live-attenuated yellow fever vaccine virus 17D (YF17D has many properties that make it an attractive vector for AIDS vaccine regimens. YF17D is well tolerated in humans and vaccination induces robust T-cell responses that persist for years. Additionally, methods to manipulate the YF17D genome have been established, enabling the generation of recombinant (rYF17D vectors carrying genes from unrelated pathogens. Here, we report the generation of seven new rYF17D viruses expressing fragments of simian immunodeficiency virus (SIVmac239 Gag, Nef, and Vif. Studies in Indian rhesus macaques demonstrated that these live-attenuated vectors replicated in vivo, but only elicited low levels of SIV-specific cellular responses. Boosting with recombinant Adenovirus type-5 (rAd5 vectors resulted in robust expansion of SIV-specific CD8(+ T-cell responses, particularly those targeting Vif. Priming with rYF17D also increased the frequency of CD4(+ cellular responses in rYF17D/rAd5-immunized macaques compared to animals that received rAd5 only. The effect of the rYF17D prime on the breadth of SIV-specific T-cell responses was limited and we also found evidence that some rYF17D vectors were more effective than others at priming SIV-specific T-cell responses. Together, our data suggest that YF17D - a clinically relevant vaccine vector - can be used to prime AIDS virus-specific T-cell responses in heterologous prime boost regimens. However, it will be important to optimize rYF17D

Navier-Stokes calculations on multi-element airfoils using a chimera-based solver

Science.gov (United States)

Jasper, Donald W.; Agrawal, Shreekant; Robinson, Brian A.

1993-01-01

A study of Navier-Stokes calculations of flows about multielement airfoils using a chimera grid approach is presented. The chimera approach utilizes structured, overlapped grids which allow great flexibility of grid arrangement and simplifies grid generation. Calculations are made for two-, three-, and four-element airfoils, and modeling of the effect of gap distance between elements is demonstrated for a two element case. Solutions are obtained using the thin-layer form of the Reynolds averaged Navier-Stokes equations with turbulence closure provided by the Baldwin-Lomax algebraic model or the Baldwin-Barth one equation model. The Baldwin-Barth turbulence model is shown to provide better agreement with experimental data and to dramatically improve convergence rates for some cases. Recently developed, improved farfield boundary conditions are incorporated into the solver for greater efficiency. Computed results show good comparison with experimental data which include aerodynamic forces, surface pressures, and boundary layer velocity profiles.

Contribution of Mouse Embryonic Stem Cells and Induced Pluripotent Stem Cells to Chimeras through Injection and Coculture of Embryos

OpenAIRE

Guo, Jitong; Wu, Baojiang; Li, Shuyu; Bao, Siqin; Zhao, Lixia; Hu, Shuxiang; Sun, Wei; Su, Jie; Dai, Yanfeng; Li, Xihe

2014-01-01

Blastocyst injection and morula aggregation are commonly used to evaluate stem cell pluripotency based on chimeric contribution of the stem cells. To assess the protocols for generating chimeras from stem cells, 8-cell mouse embryos were either injected or cocultured with mouse embryonic stem cells and induced pluripotent stem cells, respectively. Although a significantly higher chimera rate resulted from blastocyst injection, the highest germline contribution resulted from injection of 8-cel...

Thoughts on the chimera method of simulation of three-dimensional viscous flow

Science.gov (United States)

Steger, Joseph L.

1991-01-01

The chimera overset grid is reviewed and discussed relative to other procedures for simulating flow about complex configurations. It is argued that while more refinement of the technique is needed, current schemes are competitive to unstructured grid schemes and should ultimately prove more useful.

Defining the biomechanical and biological threshold of murine mild traumatic brain injury using CHIMERA (Closed Head Impact Model of Engineered Rotational Acceleration).

Science.gov (United States)

Namjoshi, Dhananjay R; Cheng, Wai Hang; Bashir, Asma; Wilkinson, Anna; Stukas, Sophie; Martens, Kris M; Whyte, Tom; Abebe, Zelalem A; McInnes, Kurt A; Cripton, Peter A; Wellington, Cheryl L

2017-06-01

CHIMERA (Closed Head Impact Model of Engineered Rotational Acceleration) is a recently described animal model of traumatic brain injury (TBI) that primarily produces diffuse axonal injury (DAI) characterized by white matter inflammation and axonal damage. CHIMERA was specifically designed to reliably generate a variety of TBI severities using precise and quantifiable biomechanical inputs in a nonsurgical user-friendly platform. The objective of this study was to define the lower limit of single impact mild TBI (mTBI) using CHIMERA by characterizing the dose-response relationship between biomechanical input and neurological, behavioral, neuropathological and biochemical outcomes. Wild-type male mice were subjected to a single CHIMERA TBI using six impact energies ranging from 0.1 to 0.7J, and post-TBI outcomes were assessed over an acute period of 14days. Here we report that single TBI using CHIMERA induces injury dose- and time-dependent changes in behavioral and neurological deficits, axonal damage, white matter tract microgliosis and astrogliosis. Impact energies of 0.4J or below produced no significant phenotype (subthreshold), 0.5J led to significant changes for one or more phenotypes (threshold), and 0.6 and 0.7J resulted in significant changes in all outcomes assessed (mTBI). We further show that linear head kinematics are the most robust predictors of duration of unconsciousness, severity of neurological deficits, white matter injury, and microgliosis following single TBI. Our data extend the validation of CHIMERA as a biofidelic animal model of DAI and establish working parameters to guide future investigations of the mechanisms underlying axonal pathology and inflammation induced by mechanical trauma. Crown Copyright © 2017. Published by Elsevier Inc. All rights reserved.

Thymectomized, irradiated, and bone marrow-reconstituted chimeras have normal cytolytic T lymphocyte precursors but a defect in lymphokine production

International Nuclear Information System (INIS)

Duprez, V.; Maziarz, R.; Weinberger, O.; Burakoff, S.J.

1984-01-01

A model system has been developed to study extrathymic T cell differentiation; mice have been thymectomized, lethally irradiated, and reconstituted with bone marrow cells depleted of Thy-1 + cells. After 8 wk, the spleen cells of these athymic, bone marrow-reconstituted chimeras contain Thy-1 + precytolytic T lymphocytes (CTL) that are able to respond to antigen only if supernatant from Con A-activated T cells is added to culture. The phenotype of these pre-CTL is similar to that of thymocytes, suggesting that they may be immature T cells. Initial evaluation of the CTL repertoire of these athymic mice demonstrated that the CTL generated to trinitrophenyl-modified syngeneic cells are H-2-restricted, and that the CTL generated to alloantigens have many of the cross-reactivities observed in normal mice but not in nude mice. In this report, the authors demonstrate a helper T cell defect in these thymectomized chimeras. These chimeras lack an Ly-1 + helper cell required for thymocytes to differentiate to CTL. Further studies revealed that when spleen cells from these thymectomized chimeras were stimulated with Con A, they produced normal levels of interleukin 2. However, these splenocytes were defective in the production of another factor needed for CTL differentiation

Inherited effects from irradiated mouse immature oocytes detected in aggregation embryo chimeras

International Nuclear Information System (INIS)

Straume, T.; Raabe, O.G.; Walsh, K.J.; Wiley, L.M.

1993-01-01

Data obtained using the mouse-preimplantation-embryo-chimera assay are presented that show a transmitted effect following low-dose irradiation of immature oocytes in vivo. Six-week-old female mice were irradiated using 137 Cs-γ-rays (0.05 Gy, 0.15 Gy, and unexposed controls). At 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 and 12 weeks post exposure, the mice were mated and aggregation chimeras made from the 4-cell embryos. Three independent experiments have now been carried out, all showing a significant embryonic cell-proliferation disadvantage of the embryos obtained from the females treated 7 weeks previously, i.e., embryos from oocytes that were immature at the time of radiation exposure. No effect was detected at 1-6 weeks when embryos were obtained from maturing oocytes. Also, the effect was not seen at 8, 9, 10, 11, and 12 weeks post exposure. The implications of these results are discussed in the light of previous studies on mouse oocytes

On the application of Chimera/unstructured hybrid grids for conjugate heat transfer

Science.gov (United States)

Kao, Kai-Hsiung; Liou, Meng-Sing

1995-01-01

A hybrid grid system that combines the Chimera overset grid scheme and an unstructured grid method is developed to study fluid flow and heat transfer problems. With the proposed method, the solid structural region, in which only the heat conduction is considered, can be easily represented using an unstructured grid method. As for the fluid flow region external to the solid material, the Chimera overset grid scheme has been shown to be very flexible and efficient in resolving complex configurations. The numerical analyses require the flow field solution and material thermal response to be obtained simultaneously. A continuous transfer of temperature and heat flux is specified at the interface, which connects the solid structure and the fluid flow as an integral system. Numerical results are compared with analytical and experimental data for a flat plate and a C3X cooled turbine cascade. A simplified drum-disk system is also simulated to show the effectiveness of this hybrid grid system.

Survival of allografts from bone marrow donors in temporary dog radiation chimeras

International Nuclear Information System (INIS)

Vriesendorp, H.M.

Complete radiation chimeras accept indefinitely a skin or a kidney graft from the bone marrow (BM) donor. The advantages of this method of inducing graft acceptance are that it does not require the use of toxic post-operative immunosuppressive agents and that the immune reactivity against antigens other than the ones carried by the BM donor remains intact. The disadvantages of this approach are that supralethal total body irradiation (TBI) causes toxicity and that allogeneic BM cells can cause lethal Graft versus Host reactions. Attempts were made to diminish the significance of these disadvantages by using lower dose TBI and giving fewer BM cells. It is shown that, in dogs, 7.5 Gy TBI followed by 4 X 10 8 BM cells.kg -1 body weight of a DLA identical sibling leads to the development of complete radiation chimeras. The exclusive presence of donor type haemopoiesis can be demonstrated by determinations of 'informative' genetic markers, i.e., markers that show different genotypes in donor and recipient. (Auth.)

The influence of specific binding of collagen-silk chimeras to silk biomaterials on hMSC behavior.

Science.gov (United States)

An, Bo; DesRochers, Teresa M; Qin, Guokui; Xia, Xiaoxia; Thiagarajan, Geetha; Brodsky, Barbara; Kaplan, David L

2013-01-01

Collagen-like proteins in the bacteria Streptococcus pyogenes adopt a triple-helix structure with a thermal stability similar to that of animal collagens, can be expressed in high yield in Escherichia coli and can be easily modified through molecular biology techniques. However, potential applications for such recombinant collagens are limited by their lack of higher order structure to achieve the physical properties needed for most biomaterials. To overcome this problem, the S. pyogenes collagen domain was fused to a repetitive Bombyx mori silk consensus sequence, as a strategy to direct specific non-covalent binding onto solid silk materials whose superior stability, mechanical and material properties have been previously established. This approach resulted in the successful binding of these new collagen-silk chimeric proteins to silk films and porous scaffolds, and the binding affinity could be controlled by varying the number of repeats in the silk sequence. To explore the potential of collagen-silk chimera for regulating biological activity, integrin (Int) and fibronectin (Fn) binding sequences from mammalian collagens were introduced into the bacterial collagen domain. The attachment of bioactive collagen-silk chimeras to solid silk biomaterials promoted hMSC spreading and proliferation substantially in comparison to the controls. The ability to combine the biomaterial features of silk with the biological activities of collagen allowed more rapid cell interactions with silk-based biomaterials, improved regulation of stem cell growth and differentiation, as well as the formation of artificial extracellular matrices useful for tissue engineering applications. Copyright © 2012 Elsevier Ltd. All rights reserved.

Artificial modulation of the gating behavior of a K+ channel in a KvAP-DNA chimera.

Directory of Open Access Journals (Sweden)

Andrew Wang

Full Text Available We present experiments where the gating behavior of a voltage-gated ion channel is modulated by artificial ligand binding. We construct a channel-DNA chimera with the KvAP potassium channel reconstituted in an artificial membrane. The channel is functional and the single channel ion conductivity unperturbed by the presence of the DNA. However, the channel opening probability vs. bias voltage, i.e., the gating, can be shifted considerably by the electrostatic force between the charges on the DNA and the voltage sensing domain of the protein. Different hybridization states of the chimera DNA thus lead to different response curves of the channel.

The Chimera Method of Simulation for Unsteady Three-Dimensional Viscous Flow

Science.gov (United States)

Meakin, Robert L.

1996-01-01

The Chimera overset grid method is reviewed and discussed in the context of a method of solution and analysis of unsteady three-dimensional viscous flows. The state of maturity of the various pieces of support software required to use the approach is discussed. A variety of recent applications of the method is presented. Current limitations of the approach are defined.

Suppressor cells in transplantation tolerance II. Maturation of suppressor cells in the bone marrow chimera

International Nuclear Information System (INIS)

Tutschka, P.J.; Ki, P.F.; Beschorner, W.E.; Hess, A.D.; Santos, G.W.

1981-01-01

Histoincompatible bone marrow allografts were established in lethally irradiated rats. At various times after transplantation, the spleen cells were harvested, subjected to mixed lymphocyte cultures, and assayed for suppressor cells in vitro and in vivo by adoptive transfer studies. Alloantigen-nonspecific suppressor cells appeared in the chimera at 40 days after grafting, coinciding with the resolution of graft-versus-host disease (GVHD). At 250 days the nonspecific suppressor cells were replaced by suppressor cells specifically suppressing donor-versus-host alloantigen responses. At 720 days suppressor cells could no longer be identified by in vitro methods but were identified by in vivo adoptive transfer of transplantation tolerance. After injection of host-type antigen into chimeras, the suppressor cells could be again demonstrated by in vitro methods

Suppressor cells in transplantation tolerance. II. maturation of suppressor cells in the bone marrow chimera

International Nuclear Information System (INIS)

Tutschka, P.J.; Ki, P.F.; Beschorner, W.E.; Hess, A.D.; Santos, G.W.

1981-01-01

Histoincompatible bone marrow allografts were established in lethally irradiated rats. At various times after transplantation, the spleen cells were harvested, subjected to mixed lymphocyte cultures, and assayed for suppressor cells in vitro and in vivo by adoptive transfer studies. Alloantigen-nonspecific suppressor cells appeared in the chimera at 40 days after grafting, coinciding with the resolution of graft-versus-host disease (GVHD). At 250 days the nonspecific suppressor cells were replaced by suppressor cells specifically suppressing donor-versus-host alloantigen responses. At 720 days suppressor cells could no longer be identified by in vitro methods but were identified by in vivo adoptive transfer of transplantation tolerance. After injection of host-type antigen into chimeras, the suppressor cells could be again demonstrated by in vitro methods

Radiosensitivity and chimera formation in Hibiscus syriacus

International Nuclear Information System (INIS)

Kwon, S.H.; Won, J.L.

1980-01-01

Radiosensitivity of gamma-irradiated Hibiscus syriacus and chimera formation were investigated. The lethal dose-50 percent with respect to seeding and cuttings was 15kR and 2 approximately 3 kR respectively, chlorophyll mutation rate of seeds irradiated with 15 kR being about 13 percent. The degree of chimeric leaf mutants from the buds by radiation treatment depends on the bud position of the branch. Buds of the middle part of V 1 branch seemed to be more multi-cellular condition than the upper and low part when irradiation was made. It is assumed that at least two primordia of V 2 branch were already differentiated from the V 1 branch in Hibiscus syriacus plant. (Author)

Programmable display of DNA-protein chimeras for controlling cell-hydrogel interactions via reversible intermolecular hybridization.

Science.gov (United States)

Zhang, Zhaoyang; Li, Shihui; Chen, Niancao; Yang, Cheng; Wang, Yong

2013-04-08

Extensive studies have been recently carried out to achieve dynamic control of cell-material interactions primarily through physicochemical stimulation. The purpose of this study was to apply reversible intermolecular hybridization to program cell-hydrogel interactions in physiological conditions based on DNA-antibody chimeras and complementary oligonucleotides. The results showed that DNA oligonucleotides could be captured to and released from the immobilizing DNA-functionalized hydrogels with high specificity via DNA hybridization. Accordingly, DNA-antibody chimeras were captured to the hydrogels, successfully inducing specific cell attachment. The cell attachment to the hydrogels reached the plateau at approximately half an hour after the functionalized hydrogels and the cells were incubated together. The attached cells were rapidly released from the bound hydrogels when triggering complementary oligonucleotides were introduced to the system. However, the capability of the triggering complementary oligonucleotides in releasing cells was affected by the length of intermolecular hybridization. The length needed to be at least more than 20 base pairs in the current experimental setting. Notably, because the procedure of intermolecular hybridization did not involve any harsh condition, the released cells maintained the same viability as that of the cultured cells. The functionalized hydrogels also exhibited the potential to catch and release cells repeatedly. Therefore, this study demonstrates that it is promising to regulate cell-material interactions dynamically through the DNA-programmed display of DNA-protein chimeras.

Transfer to Intermediate Forms Following Concept Discrimination by Pigeons: Chimeras and Morphs

Science.gov (United States)

Ghosh, Natasha; Lea, S. E. G.; Noury, Malia

2004-01-01

Two experiments examined pigeons' generalization to intermediate forms following training of concept discriminations. In Experiment 1, the training stimuli were sets of images of dogs and cats, and the transfer stimuli were head/body chimeras, which humans tend to categorize more readily in terms of the head part rather than the body part. In…

Characterization of hemopoietic stem cell chimerism in antibody-facilitated bone marrow chimeras

International Nuclear Information System (INIS)

Francescutti, L.H.; Gambel, P.; Wegmann, T.G.

1985-01-01

The authors have previously described a model for bone marrow transplantation that involves preparation of the host with monoclonal antibody against class I or class II antigens instead of irradiation or cytotoxic drugs. This allows engraftment and subsequent repopulation of the host by donor tissue. They have previously reported on chimerism in the peripheral blood of P1----(P1 X P2)F1 animals. In this report, the authors describe the examination of the bone marrow and spleen stem cell chimerism of these antibody-facilitated (AF) chimeras, by determining, with an isozyme assay, the phenotype of methylcellulose colonies grown from stem cells. They have found a correlation between peripheral blood chimerism and the stem cell constitution of both spleen and bone marrow. The peripheral blood chimerism also correlates with the level of chimerism in macrophages derived from peritoneal exudate cells. These findings indicate that assaying the peripheral blood of such chimeras provides an excellent indication of the degree of chimerism at the stem cell level and stands in sharp contrast to the level of chimerism in certain lymphoid compartments

Bacterial expression and one-step purification of an isotope-labeled heterotrimeric G-protein α-subunit

International Nuclear Information System (INIS)

Abdulaev, Najmoutin G.; Zhang Cheng; Dinh, Andy; Ngo, Tony; Bryan, Philip N.; Brabazon, Danielle M.; Marino, John P.; Ridge, Kevin D.

2005-01-01

Heterologous expression systems are often employed to generate sufficient quantities of isotope-labeled proteins for high-resolution NMR studies. Recently, the interaction between the prodomain region of subtilisin and an active, mutant form of the mature enzyme has been exploited to develop a cleavable affinity tag fusion system for one-step generation and purification of full-length soluble proteins obtained by inducible prokaryotic expression. As a first step towards applying high-resolution NMR methods to study heterotrimeric G-protein α-subunit (G α ) conformation and dynamics, the utility of this subtilisin prodomain fusion system for expressing and purifying an isotope-labeled G α chimera (∼40 kDa polypeptide) has been tested. The results show that a prodomain fused G α chimera can be expressed to levels approaching 6-8 mg/l in minimal media and that the processed, mature protein exhibits properties similar to those of G α isolated from natural sources. To assay for the functional integrity of the purified G α chimera at NMR concentrations and probe for changes in the structure and dynamics of G α that result from activation, 15 N-HSQC spectra of the GDP/Mg 2+ bound form of G α obtained in the absence and presence of aluminum fluoride, a well known activator of the GDP bound state, have been acquired. Comparisons of the 15 N-HSQC spectra reveals a number of changes in chemical shifts of the 1 HN, 15 N crosspeaks that are discussed with respect to expected changes in the protein conformation associated with G α activation

H-2-incompatible bone marrow chimeras produce donor-H-2-restricted Ly-2 suppressor T-cell factor(s)

International Nuclear Information System (INIS)

Noguchi, M.; Onoe, K.; Ogasawara, M.; Iwabuchi, K.; Geng, L.; Ogasawara, K.; Good, R.A.; Morikawa, K.

1985-01-01

To study adaptive-differentiation phenomena of T lymphocytes, suppressor T-cell factors (TsF) produced by Ly-2+ splenic T cells from fully allogeneic mouse bone marrow chimeras were analyzed. AKR mice irradiated and reconstituted with B10 marrow cells (B10----AKR chimeras) produced an Ly-2+ TsF after hyperimmunization with sheep erythrocytes. The TsF suppressed primary antibody responses (to sheep erythrocytes) generated with spleen cells of mice of H-2b haplotype but not those of H-2k haplotype. Thus, this suppressor factor was donor-H-2-restricted. The immunoglobulin heavy chain variable region gene (Igh-V)-restricting element was not involved in this form of suppression. Similar results were obtained when TsF from B6----BALB/c and BALB/c----B6 chimeras were analyzed. The TsF from B10----AKR chimeras suppressed responses of B10.A(3R) and B10.A(5R) mice but not those of B10.A(4R). This finding showed that identity between the factor-producing cells and target spleen cells is required on the left-hand side of the E beta locus of the H-2 region and that the putative I-Jb locus is not involved in this form of suppression. The present results support the postulate that post-thymic differentiation in the presence of continued or repeated stimulation with antigen and donor-derived antigen-presenting cells generates donor-H-2-restricted T-cell clones that may predominate within the repertoire of the specific antigen being presented

Chaos in Dirac electron optics: Emergence of a relativistic quantum chimera

OpenAIRE

Xu, Hong-Ya; Wang, Guang-Lei; Huang, Liang; Lai, Ying-Cheng

2018-01-01

We uncover a remarkable quantum scattering phenomenon in two-dimensional Dirac material systems where the manifestations of both classically integrable and chaotic dynamics emerge simultaneously and are electrically controllable. The distinct relativistic quantum fingerprints associated with different electron spin states are due to a physical mechanism analogous to chiroptical effect in the presence of degeneracy breaking. The phenomenon mimics a chimera state in classical complex dynamical ...

Contrasting feature in the repopulation of host-type T cells in the spleens of F1----P and P----F1 radiation bone marrow chimeras

International Nuclear Information System (INIS)

Hirokawa, K.; Sado, T.; Kubo, S.; Kamisaku, H.; Utsuyama, M.

1986-01-01

The regeneration and persistence of host- and donor-derived T cells were examined in the thymus as well as the spleen of mouse radiation bone marrow chimeras of two semiallogeneic combinations (F1----P, P----F1) with different Thy-1 markers on T cells of donor and host origins. An unexpectedly large number of host-type T cells were recovered from the spleens of F1----P chimeras, amounting to as high as 45 and 25% of total T cells at 6 and 14 weeks after bone marrow transplantation (BMT), respectively. To the contrary, the residual host-type T cells in the spleens of P----F1 chimeras disappeared quickly, resulting in less than 0.1% of total T cells at 6 weeks after BMT. It was also revealed that the number of host-type T cells in the spleens of F1----P chimeras decreased in proportion to increase of radiation dose given to the recipients

Anti-bacterial immunity to Listeria monocytogenes in allogeneic bone marrow chimera in mice

International Nuclear Information System (INIS)

Onoe, K.; Good, R.A.; Yamamoto, K.

1986-01-01

Protection and delayed-type hypersensitivity (DTH) to the facultative intracellular bacterium Listeria monocytogenes (L.m.) were studied in allogeneic and syngeneic bone marrow chimeras. Lethally irradiated AKR (H-2k) mice were successfully reconstituted with marrow cells from C57BL/10 (B10) (H-2b), B10 H-2-recombinant strains or syngeneic mice. Irradiated AKR mice reconstituted with marrow cells from H-2-compatible B10.BR mice, [BR----AKR], as well as syngeneic marrow cells, [AKR----AKR], showed a normal level of responsiveness to the challenge stimulation with the listeria antigens when DTH was evaluated by footpad reactions. These mice also showed vigorous activities in acquired resistance to the L.m. By contrast, chimeric mice that had total or partial histoincompatibility at the H-2 determinants between donor and recipient, [B10----AKR], [B10.AQR----AKR], [B10.A(4R)----AKR], or [B10.A(5R)----AKR], were almost completely unresponsive in DTH and antibacterial immunity. However, when [B10----AKR] H-2-incompatible chimeras had been immunized with killed L.m. before challenge with live L.m., these mice manifested considerable DTH and resistance to L.m. These observations suggest that compatibility at the entire MHC between donor and recipient is required for bone marrow chimeras to be able to manifest DTH and protection against L.m. after a short-term immunization schedule. However, this requirement is overcome by a preceding or more prolonged period of immunization with L.m. antigens. These antigens, together with marrow-derived antigen-presenting cells, can then stimulate and expand cell populations that are restricted to the MHC (H-2) products of the donor type

Histopathological changes in exocrine glands of murine transplantation chimeras. II: Sjögren's syndrome-like exocrinopathy in mice without lupus nephritis. A model of primary Sjögren's syndrome

DEFF Research Database (Denmark)

Ussing, Anne Phaff; Prause, J.U.; Sørensen, Inger

1992-01-01

Autoimmune disease, primary Sjögren's syndrome, transplantation chimeras, experimental model, exocrinopathy, inbred mouse strains......Autoimmune disease, primary Sjögren's syndrome, transplantation chimeras, experimental model, exocrinopathy, inbred mouse strains...

New type of chimera structures in a ring of bistable FitzHugh–Nagumo oscillators with nonlocal interaction

Energy Technology Data Exchange (ETDEWEB)

Shepelev, I.A., E-mail: igor_sar@li.ru; Vadivasova, T.E., E-mail: vadivasovate@yandex.ru; Bukh, A.V., E-mail: buh.andrey@yandex.ru; Strelkova, G.I., E-mail: strelkovagi@info.sgu.ru; Anishchenko, V.S., E-mail: wadim@info.sgu.ru

2017-04-25

We study the spatiotemporal dynamics of a ring of nonlocally coupled FitzHugh–Nagumo oscillators in the bistable regime. A new type of chimera patterns has been found in the noise-free network and when isolated elements do not oscillate. The region of existence of these structures has been explored when the coupling range and the coupling strength between the network elements are varied. - Highlights: • Dynamics of a ring of nonlocally coupled FitzHugh–Nagumo oscillators in the bistable regime is studied. • A new type of chimera patterns has been found in the noise-free network. • The region of existence of new structures has been explored when varying the coupling parameters.

Interaction of chimera states in a multilayered network of nonlocally coupled oscillators

Science.gov (United States)

Goremyko, M. V.; Maksimenko, V. A.; Makarov, V. V.; Ghosh, D.; Bera, B.; Dana, S. K.; Hramov, A. E.

2017-08-01

The processes of formation and evolution of chimera states in the model of a multilayered network of nonlinear elements with complex coupling topology are studied. A two-layered network of nonlocally intralayer-coupled Kuramoto-Sakaguchi phase oscillators is taken as the object of investigation. Different modes implemented in this system upon variation of the degree of interlayer interaction are demonstrated.

Vaccination with Gag, Vif, and Nef gene fragments affords partial control of viral replication after mucosal challenge with SIVmac239.

Science.gov (United States)

Martins, Mauricio A; Wilson, Nancy A; Piaskowski, Shari M; Weisgrau, Kim L; Furlott, Jessica R; Bonaldo, Myrna C; Veloso de Santana, Marlon G; Rudersdorf, Richard A; Rakasz, Eva G; Keating, Karen D; Chiuchiolo, Maria J; Piatak, Michael; Allison, David B; Parks, Christopher L; Galler, Ricardo; Lifson, Jeffrey D; Watkins, David I

2014-07-01

Broadly targeted cellular immune responses are thought to be important for controlling replication of human and simian immunodeficiency viruses (HIV and SIV). However, eliciting such responses by vaccination is complicated by immunodominance, the preferential targeting of only a few of the many possible epitopes of a given antigen. This phenomenon may be due to the coexpression of dominant and subdominant epitopes by the same antigen-presenting cell and may be overcome by distributing these sequences among several different vaccine constructs. Accordingly, we tested whether vaccinating rhesus macaques with "minigenes" encoding fragments of Gag, Vif, and Nef resulted in broadened cellular responses capable of controlling SIV replication. We delivered these minigenes through combinations of recombinant Mycobacterium bovis BCG (rBCG), electroporated recombinant DNA (rDNA) along with an interleukin-12 (IL-12)-expressing plasmid (EP rDNA plus pIL-12), yellow fever vaccine virus 17D (rYF17D), and recombinant adenovirus serotype 5 (rAd5). Although priming with EP rDNA plus pIL-12 increased the breadth of vaccine-induced T-cell responses, this effect was likely due to the improved antigen delivery afforded by electroporation rather than modulation of immunodominance. Indeed, Mamu-A*01(+) vaccinees mounted CD8(+) T cells directed against only one subdominant epitope, regardless of the vaccination regimen. After challenge with SIVmac239, vaccine efficacy was limited to a modest reduction in set point in some of the groups and did not correlate with standard T-cell measurements. These findings suggest that broad T-cell responses elicited by conventional vectors may not be sufficient to substantially contain AIDS virus replication. Immunodominance poses a major obstacle to the generation of broadly targeted, HIV-specific cellular responses by vaccination. Here we attempted to circumvent this phenomenon and thereby broaden the repertoire of SIV-specific cellular responses by

A Biochemical/Biophysical Assay Dyad for HTS-Compatible Triaging of Inhibitors of the HIV-1 Nef/Hck SH3 Interaction

KAUST Repository

Breuer, Sebastian

2013-07-26

The current treatment regimens for HIV include over 20 anti-retrovirals. However, adverse drug effects and the emergence of drug resistance necessitates the continued improvement of the existing drug classes as well as the development of novel drugs that target as yet therapeutically unexploited viral and cellular pathways. Here we demonstrate a strategy for the discovery of protein-protein interaction inhibitors of the viral pathogenicity factor HIV-1 Nef and its interaction with the host factor SH3. A combination of a time-resolved fluorescence resonance energy resonance energy transfer-based assay and a label-free resonant waveguide grating-based assay was optimized for high-throughput screening formats.

A Biochemical/Biophysical Assay Dyad for HTS-Compatible Triaging of Inhibitors of the HIV-1 Nef/Hck SH3 Interaction

KAUST Repository

Breuer, Sebastian; Espinola, Sheryll; Morelli, Xavier; Torbett, Bruce E; Arold, Stefan T.; Engels, Ingo H

2013-01-01

The current treatment regimens for HIV include over 20 anti-retrovirals. However, adverse drug effects and the emergence of drug resistance necessitates the continued improvement of the existing drug classes as well as the development of novel drugs that target as yet therapeutically unexploited viral and cellular pathways. Here we demonstrate a strategy for the discovery of protein-protein interaction inhibitors of the viral pathogenicity factor HIV-1 Nef and its interaction with the host factor SH3. A combination of a time-resolved fluorescence resonance energy resonance energy transfer-based assay and a label-free resonant waveguide grating-based assay was optimized for high-throughput screening formats.

"American Chimera: The Ever-Present Domination of Whiteness, Patriarchy, and Capitalism…A Parable"

Science.gov (United States)

Montoya, Roberto; Matias, Cheryl E.; Nishi, Naomi W. M.; Sarcedo, Geneva L.

2016-01-01

In Greek mythology, the Chimera is a fire-breathing monster with three heads: one of a lion, one of a horned goat, and one of a powerful dragon. Of similar construction is the presence of three structures in US society, whiteness, patriarchy, and capitalism, which are overwhelmingly represented, valued, and espoused when examining areas of…

Recipient micro-environment does not dictate the Igh-V restriction specificity of T cell suppressor inducer factor (TsiF) from allogeneic bone marrow chimera in mice

International Nuclear Information System (INIS)

Noguchi, M.; Ogasawara, M.; Iwabuchi, K.; Osgasawara, K.; Ishihara, T.; Good, R.A.; Morikawa, K.; Onoe, K.

1985-01-01

The authors have ascertained previously from a study of fully allogeneic irradiation chimeras in mice that the H-2 restriction of the suppressor factor (Ly-2 T suppressor factor) is determined by the post-thymic environment protected by the donor cells, rather than by the thymic environment of the recipient. In the present study, the author analyzed differentiation influences that determine the Igh restriction specificities of the suppressor inducer T cell factor(s) (TsiF) that are produced by Ly-1+ splenic T cells in fully allogeneic bone marrow chimeras in mice. AKR mice that had been lethally irradiated and reconstituted with B10 marrow cells, [B10----AKR] chimeras, produced Ly-1 TsiF after hyper-immunization with sheep erythrocytes (SRBC) which suppressed antigen--specifically the primary antibody responses to SRBC that were generated in cells of the same Igh-Vb haplotype of donor strain and not those generated in cells of the recipient Igh-Va type. Similar results were obtained when Ly-1 TsiF from [B6----BALB/c] and [BALB/c----B6] chimeras were analyzed. Furthermore, the Ly-1 TsiF from [BALB/c----B6] chimeras suppressed the primary antibody responses of both BALB/c [H-2d, Igh-Va, Igh-Ca] and BAB-14 (H-2d, Igh-Va, Igh-Cb), but not those of CAL-20 (H-2d, Igh-Vd, Igh-Cd). These results demonstrate clearly that the Ly-1 TsiF from allogeneic bone marrow chimeras are donor Igh-V-restricted and are not influenced by the recipient micro-environment, presumably that were provided by the thymuses of the recipient mice

Bacterial expression and one-step purification of an isotope-labeled heterotrimeric G-protein {alpha}-subunit

Energy Technology Data Exchange (ETDEWEB)

Abdulaev, Najmoutin G. [University of Maryland Biotechnology Institute, Center for Advanced Research in Biotechnology (United States); Zhang Cheng; Dinh, Andy [University of Texas Health Science Center, Center for Membrane Biology, Department of Biochemistry and Molecular Biology (United States); Ngo, Tony; Bryan, Philip N. [University of Maryland Biotechnology Institute, Center for Advanced Research in Biotechnology (United States); Brabazon, Danielle M. [Loyola College in Maryland, Department of Chemistry (United States); Marino, John P. [University of Maryland Biotechnology Institute, Center for Advanced Research in Biotechnology (United States)], E-mail: marino@carb.nist.gov; Ridge, Kevin D. [University of Texas Health Science Center, Center for Membrane Biology, Department of Biochemistry and Molecular Biology (United States)

2005-05-15

Heterologous expression systems are often employed to generate sufficient quantities of isotope-labeled proteins for high-resolution NMR studies. Recently, the interaction between the prodomain region of subtilisin and an active, mutant form of the mature enzyme has been exploited to develop a cleavable affinity tag fusion system for one-step generation and purification of full-length soluble proteins obtained by inducible prokaryotic expression. As a first step towards applying high-resolution NMR methods to study heterotrimeric G-protein {alpha}-subunit (G{sub {alpha}}) conformation and dynamics, the utility of this subtilisin prodomain fusion system for expressing and purifying an isotope-labeled G{sub {alpha}} chimera ({approx}40 kDa polypeptide) has been tested. The results show that a prodomain fused G{sub {alpha}} chimera can be expressed to levels approaching 6-8 mg/l in minimal media and that the processed, mature protein exhibits properties similar to those of G{sub {alpha}} isolated from natural sources. To assay for the functional integrity of the purified G{sub {alpha}} chimera at NMR concentrations and probe for changes in the structure and dynamics of G{sub {alpha}} that result from activation, {sup 15}N-HSQC spectra of the GDP/Mg{sup 2+} bound form of G{sub {alpha}} obtained in the absence and presence of aluminum fluoride, a well known activator of the GDP bound state, have been acquired. Comparisons of the {sup 15}N-HSQC spectra reveals a number of changes in chemical shifts of the {sup 1}HN, {sup 15}N crosspeaks that are discussed with respect to expected changes in the protein conformation associated with G{sub {alpha}} activation.

Distinct fates of self-specific T cells developing in irradiation bone marrow chimeras: Clonal deletion, clonal anergy, or in vitro responsiveness to self-Mls-1a controlled by hemopoietic cells in the thymus

International Nuclear Information System (INIS)

Speiser, D.E.; Chvatchko, Y.; Zinkernagel, R.M.; MacDonald, H.R.

1990-01-01

Elimination of potentially self-reactive T lymphocytes during their maturation in the thymus has been shown to be a major mechanism in accomplishing self-tolerance. Previous reports demonstrated that clonal deletion of self-Mls-1a-specific V beta 6+ T lymphocyte is controlled by a radiosensitive I-E+ thymic component. Irradiation chimeras reconstituted with I-E- bone marrow showed substantial numbers of mature V beta 6+ T cells despite host Mls-1a expression. Analysis of the functional properties of such chimeric T cells revealed a surprising variability in their in vitro reactivity to host Mls-1a, depending on the H-2 haplotype of stem cells used for reconstitution. In chimeras reconstituted with B10.S (H-2s) stem cells, mature V beta 6+ lymphocytes were present but functionally anergic to host-type Mls-1a in vitro. In contrast, in chimeras reconstituted with B10.G (H-2q) bone marrow, nondeleted V beta 6+ cells were highly responsive to Mls-1a in vitro. These findings suggest that clonal anergy of V beta 6+ cells to self-Mls-1a may be controlled by the affinity/avidity of T cell receptor interactions with bone marrow-derived cells in the thymus depending on the major histocompatibility complex class II molecules involved. Furthermore, chimeras bearing host (Mls-1a)-reactive V beta 6+ cells did not differ clinically from those with anergic or deleted V beta 6+ cells and survived more than one year without signs of autoimmune disease. Interestingly, their spleen cells had no Mls-1a stimulatory capacity in vitro. Therefore, regulation at the level of antigen presentation may be an alternative mechanism for maintenance of tolerance to certain self-antigens such as Mls-1a

A C-terminal segment of the V{sub 1}R vasopressin receptor is unstructured in the crystal structure of its chimera with the maltose-binding protein

Energy Technology Data Exchange (ETDEWEB)

Adikesavan, Nallini Vijayarangan; Mahmood, Syed Saad; Stanley, Nithianantham; Xu, Zhen; Wu, Nan [Department of Biochemistry, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106-4935 (United States); Thibonnier, Marc [Department of Medicine, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106-4935 (United States); Shoham, Menachem, E-mail: mxs10@case.edu [Department of Biochemistry, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106-4935 (United States)

2005-04-01

The 1.8 Å crystal structure of an MBP-fusion protein with the C-terminal cytoplasmic segment of the V1 vasopressin receptor reveals that the receptor segment is unstructured. The V{sub 1} vascular vasopressin receptor (V{sub 1}R) is a G-protein-coupled receptor (GPCR) involved in the regulation of body-fluid osmolality, blood volume and blood pressure. Signal transduction is mediated by the third intracellular loop of this seven-transmembrane protein as well as by the C-terminal cytoplasmic segment. A chimera of the maltose-binding protein (MBP) and the C-terminal segment of V{sub 1}R has been cloned, expressed, purified and crystallized. The crystals belong to space group P2{sub 1}, with unit-cell parameters a = 51.10, b = 66.56, c = 115.72 Å, β = 95.99°. The 1.8 Å crystal structure reveals the conformation of MBP and part of the linker region of this chimera, with the C-terminal segment being unstructured. This may reflect a conformational plasticity in the C-terminal segment that may be necessary for proper function of V{sub 1}R.

High-level expression and characterization of a chimeric lipase from Rhizopus oryzae for biodiesel production.

Science.gov (United States)

Yu, Xiao-Wei; Sha, Chong; Guo, Yong-Liang; Xiao, Rong; Xu, Yan

2013-02-21

Production of biodiesel from non-edible oils is receiving increasing attention. Tung oil, called "China wood oil" is one kind of promising non-edible biodiesel oil in China. To our knowledge, tung oil has not been used to produce biodiesel by enzymatic method. The enzymatic production of biodiesel has been investigated extensively by using Rhizopus oryzae lipase as catalyst. However, the high cost of R. oryzae lipase remains a barrier for its industrial applications. Through different heterologous expression strategies and fermentation techniques, the highest expression level of the lipase from R. oryzae reached 1334 U/mL in Pichia pastoris, which is still not optimistic for industry applications. The prosequence of lipases from Rhizopus sp. is very important for the folding and secretion of an active lipase. A chimeric lipase from R. oryzae was constructed by replacing the prosequence with that from the R. chinensis lipase and expressed in P. pastoris. The maximum activity of the chimera reached 4050 U/mL, which was 11 fold higher than that of the parent. The properties of the chimera were studied. The immobilized chimera was used successfully for biodiesel production from tung oil, which achieved higher FAME yield compared with the free chimeric lipase, non-chimeric lipase and mature lipase. By response surface methodology, three variables, water content, methanol to tung oil molar ratio and enzyme dosage were proved to be crucial parameters for biosynthesis of FAME and the FAME yield reached 91.9±2.5% at the optimized conditions by adding 5.66 wt.% of the initial water based on oil weight, 3.88 of methanol to tung oil molar ratio and 13.24 wt.% of enzyme concentration based on oil weight at 40°C. This is the first report on improving the expression level of the lipase from R. oryzae by replacing prosequences. The immobilized chimera was used successfully for biodiesel production from tung oil. Using tung oil as non-edible raw material and a chimeric lipase

Enhancing production and cytotoxic activity of polymeric soluble FasL-based chimeric proteins by concomitant expression of soluble FasL.

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Aurore Morello

Full Text Available Membrane FasL is the natural trigger of Fas-mediated apoptosis. A soluble homotrimeric counterpart (sFasL also exists which is very weakly active, and needs oligomerization beyond its trimeric state to induce apoptosis. We recently generated a soluble FasL chimera by fusing the immunoglobulin-like domain of the leukemia inhibitory factor receptor gp190 to the extracellular region of human FasL, which enabled spontaneous dodecameric homotypic polymerization of FasL. This polymeric soluble human FasL (pFasL displayed anti-tumoral activity in vitro and in vivo without systemic cytotoxicity in mouse. In the present work, we focused on the improvement of pFasL, with two complementary objectives. First, we developed more complex pFasL-based chimeras that contained a cell-targeting module. Secondly, we attempted to improve the production and/or the specific activity of pFasL and of the cell-targeting chimeras. We designed two chimeras by fusing to pFasL the extracellular portions of the HLA-A2 molecule or of a human gamma-delta TCR, and analyzed the consequences of co-expressing these molecules or pFasL together with sFasL on their heterotopic cell production. This strategy significantly enhanced the production of pFasL and of the two chimeras, as well as the cytotoxic activity of the two chimeras but not of pFasL. These results provide the proof of concept for an optimization of FasL-based chimeric proteins for a therapeutic use.

Approximate Waveforms for Extreme-Mass-Ratio Inspirals: The Chimera Scheme

International Nuclear Information System (INIS)

Sopuerta, Carlos F; Yunes, Nicolás

2012-01-01

We describe a new kludge scheme to model the dynamics of generic extreme-mass-ratio inspirals (EMRIs; stellar compact objects spiraling into a spinning supermassive black hole) and their gravitational-wave emission. The Chimera scheme is a hybrid method that combines tools from different approximation techniques in General Relativity: (i) A multipolar, post-Minkowskian expansion for the far-zone metric perturbation (the gravitational waveforms) and for the local prescription of the self-force; (ii) a post-Newtonian expansion for the computation of the multipole moments in terms of the trajectories; and (iii) a BH perturbation theory expansion when treating the trajectories as a sequence of self-adjusting Kerr geodesies. The EMRI trajectory is made out of Kerr geodesic fragments joined via the method of osculating elements as dictated by the multipolar post-Minkowskian radiation-reaction prescription. We implemented the proper coordinate mapping between Boyer-Lindquist coordinates, associated with the Kerr geodesies, and harmonic coordinates, associated with the multipolar post-Minkowskian decomposition. The Chimera scheme is thus a combination of approximations that can be used to model generic inspirals of systems with extreme to intermediate mass ratios, and hence, it can provide valuable information for future space-based gravitational-wave observatories, like LISA, and even for advanced ground detectors. The local character in time of our multipolar post-Minkowskian self-force makes this scheme amenable to study the possible appearance of transient resonances in generic inspirals.

Dominance and persistence of donor marrow in long-lived allogeneic radiation chimeras obtained with unmanipulated bone marrow

International Nuclear Information System (INIS)

Pierpaoli, W.; Maestroni, G.J.M.

1983-01-01

Allogeneic, H-2-incompatible irradiation chimeras (H-2sup(d) → H-2sup(b)) constructed with normal, unmanipulated bone marrow and with marrow-derived factors live long and do not manifest a GvH disease. Their response to primary immunization is deficient but their alloreactivity is normal. This chimeric allotolerance cannot be passively transferred from chimeric donors to normal irradiated recipients. Passive transfer of both donor- or recipient-type immuno-competent T-cells into the chimeric mice does not lead to syngeneic reconstitution, rejection of the engrafted marrow or GvH disease, and the mice maintain permanently their chimerism. This new model demonstrates that chimerism is not eradicable in long-lived chimeras reconstituted with unmanipulated bone marrow, and that the bone marrow itself plays a dominant role in maintenance of chimerism. (Auth.)

Human iPSC Glial Mouse Chimeras Reveal Glial Contributions to Schizophrenia

DEFF Research Database (Denmark)

Windrem, Martha S.; Osipovitch, Mikhail; Liu, Zhengshan

2017-01-01

with childhood-onset SCZ. After neonatal implantation into myelin-deficient shiverer mice, SCZ GPCs showed premature migration into the cortex, leading to reduced white matter expansion and hypomyelination relative to controls. The SCZ glial chimeras also showed delayed astrocytic differentiation and abnormal...... astrocytic morphologies. When established in myelin wild-type hosts, SCZ glial mice showed reduced prepulse inhibition and abnormal behavior, including excessive anxiety, antisocial traits, and disturbed sleep. RNA-seq of cultured SCZ human glial progenitor cells (hGPCs) revealed disrupted glial...

Periodic synchronization and chimera in conformist and contrarian oscillators

Science.gov (United States)

Hong, Hyunsuk

2014-06-01

We consider a system of phase oscillators that couple with both attractive and repulsive interaction under a pinning force and explore collective behavior of the system. The oscillators can be divided into two subpopulations of "conformist" oscillators with attractive interaction and "contrarian" ones with repulsive interaction. We find that the interplay between the pinning force and the opposite relationship of the conformist and contrarian oscillators induce peculiar dynamic states: periodic synchronization, breathing chimera, and fully pinned state depending on the fraction of the conformists. Using the Watanabe-Strogatz transformation, we reduce the dynamics into a low-dimensional one and find that the above dynamic states are generated from the reduced dynamics.

Chimeras and Mirages of the Golden Horde

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V.A. Ivanov

2014-01-01

Full Text Available The article examines the problem of so-called “imperial culture” of the Golden Horde. The author analyzes the archaeological material regarding it as a component of “imperial culture”. The author evaluates the quality of the archaeological material as well as the breadth and intensity of its distribution among the population of the Golden Horde and the neighboring tribal areas, which the author considers a priori as consumers of this “imperial culture”. Based on this analysis, the author concludes that in general, the concept of “imperial culture” of the Golden Horde is a chimera. In turn, the expected powerful effect of “imperial culture” of the Golden Horde in the culture of neighboring peoples of the Urals and the Volga region is a mirage created by the imagination of researchers.

Grid adaptation using chimera composite overlapping meshes

Science.gov (United States)

Kao, Kai-Hsiung; Liou, Meng-Sing; Chow, Chuen-Yen

1994-01-01

The objective of this paper is to perform grid adaptation using composite overlapping meshes in regions of large gradient to accurately capture the salient features during computation. The chimera grid scheme, a multiple overset mesh technique, is used in combination with a Navier-Stokes solver. The numerical solution is first converged to a steady state based on an initial coarse mesh. Solution-adaptive enhancement is then performed by using a secondary fine grid system which oversets on top of the base grid in the high-gradient region, but without requiring the mesh boundaries to join in any special way. Communications through boundary interfaces between those separated grids are carried out using trilinear interpolation. Application to the Euler equations for shock reflections and to shock wave/boundary layer interaction problem are tested. With the present method, the salient features are well-resolved.

Characteristics of macrophages in irradiation chimeras in mice reconstituted with allogeneic bone marrow cells

International Nuclear Information System (INIS)

Yasumizu, R.; Onoe, K.; Iwabuchi, K.; Ogasawara, M.; Fujita, M.; Okuyama, H.; Good, R.A.; Morikawa, K.

1985-01-01

Biological and immunological characteristics of the reticuloendothelial system of irradiation bone marrow chimeric mice and macrophages collected from various tissue sources of the mice were studied. The chimeras showed comparable activities in carbon clearance to those of normal donor or recipient mice. The macrophages from spleen, lymph node, bone marrow, peripheral blood, liver, peritoneal cavity, and lung were demonstrated to be of donor marrow origin. They showed almost the same enzyme activities and phagocytic capability of sheep erythrocytes (SRBC, E), SRBC sensitized with anti-SRBC IgG (EA), and SRBC sensitized with anti-SRBC IgM and coated with complement (EAC) as those of normal mice. Proportions of Fc receptor and complement receptor-positive cells are also in normal range. In addition, the antigen-presenting capability of the chimeric macrophages for in vitro primary antibody response to SRBC was intact. These observations suggest that the reticuloendothelial system and macrophages of allogeneic bone marrow chimeras where donor and recipient differ at the major histocompatibility complex have no defect so far as could be ascertained by the present study

Brucella-Salmonella lipopolysaccharide chimeras are less permeable to hydrophobic probes and more sensitive to cationic peptides and EDTA than are their native Brucella sp. counterparts.

Science.gov (United States)

Freer, E; Moreno, E; Moriyón, I; Pizarro-Cerdá, J; Weintraub, A; Gorvel, J P

1996-01-01

A rough (R) Brucella abortus 45/20 mutant was more sensitive to the bactericidal activity of polymyxin B and lactoferricin B than was its smooth (S) counterpart but considerably more resistant than Salmonella montevideo. The outer membrane (OM) and isolated lipopolysaccharide (LPS) of S. montevideo showed a higher affinity for these cationic peptides than did the corresponding B. abortus OM and LPS. We took advantage of the moderate sensitivity of R B. abortus to cationic peptides to construct live R B. abortus-S-LPS chimeras to test the activities of polymyxin B, lactoferricin B, and EDTA. Homogeneous and abundant peripheral distribution of the heterologous S-LPS was observed on the surface of the chimeras, and this coating had no effect on the viability or morphology of the cells. When the heterologous LPS corresponded to the less sensitive bacterium S B. abortus S19, the chimeras were more resistant to cationic peptides; in contrast, when the S-LPS was from the more sensitive bacterium S. montevideo, the chimeras were more susceptible to the action of peptides and EDTA. A direct correlation between the amount of heterologous S-LPS on the surface of chimeric Brucella cells and peptide sensitivity was observed. Whereas the damage produced by polymyxin B in S. montevideo and B. abortus-S. montevideo S-LPS chimeras was manifested mainly as OM blebbing and inner membrane rolling, lactoferricin B caused inner membrane detachment, vacuolization, and the formation of internal electron-dense granules in these cells. Native S and R B. abortus strains were permeable to the hydrophobic probe N-phenyl-1-naphthylamine (NPN). In contrast, only reduced amounts of NPN partitioned into the OMs of the S. montevideo and B. abortus-S. montevideo S-LPS chimeras. Following peptide exposure, accelerated NPN uptake similar to that observed for S. montevideo was detected for the B. abortus-S. montevideo LPS chimeras. The partition of NPN into native or EDTA-, polymyxin B-, or

Brucella-Salmonella lipopolysaccharide chimeras are less permeable to hydrophobic probes and more sensitive to cationic peptides and EDTA than are their native Brucella sp. counterparts.

Science.gov (United States)

Freer, E; Moreno, E; Moriyón, I; Pizarro-Cerdá, J; Weintraub, A; Gorvel, J P

1996-10-01

A rough (R) Brucella abortus 45/20 mutant was more sensitive to the bactericidal activity of polymyxin B and lactoferricin B than was its smooth (S) counterpart but considerably more resistant than Salmonella montevideo. The outer membrane (OM) and isolated lipopolysaccharide (LPS) of S. montevideo showed a higher affinity for these cationic peptides than did the corresponding B. abortus OM and LPS. We took advantage of the moderate sensitivity of R B. abortus to cationic peptides to construct live R B. abortus-S-LPS chimeras to test the activities of polymyxin B, lactoferricin B, and EDTA. Homogeneous and abundant peripheral distribution of the heterologous S-LPS was observed on the surface of the chimeras, and this coating had no effect on the viability or morphology of the cells. When the heterologous LPS corresponded to the less sensitive bacterium S B. abortus S19, the chimeras were more resistant to cationic peptides; in contrast, when the S-LPS was from the more sensitive bacterium S. montevideo, the chimeras were more susceptible to the action of peptides and EDTA. A direct correlation between the amount of heterologous S-LPS on the surface of chimeric Brucella cells and peptide sensitivity was observed. Whereas the damage produced by polymyxin B in S. montevideo and B. abortus-S. montevideo S-LPS chimeras was manifested mainly as OM blebbing and inner membrane rolling, lactoferricin B caused inner membrane detachment, vacuolization, and the formation of internal electron-dense granules in these cells. Native S and R B. abortus strains were permeable to the hydrophobic probe N-phenyl-1-naphthylamine (NPN). In contrast, only reduced amounts of NPN partitioned into the OMs of the S. montevideo and B. abortus-S. montevideo S-LPS chimeras. Following peptide exposure, accelerated NPN uptake similar to that observed for S. montevideo was detected for the B. abortus-S. montevideo LPS chimeras. The partition of NPN into native or EDTA-, polymyxin B-, or

Bovine and human lactoferricin peptides: chimeras and new cyclic analogs.

Science.gov (United States)

Arias, Mauricio; McDonald, Lindsey J; Haney, Evan F; Nazmi, Kamran; Bolscher, Jan G M; Vogel, Hans J

2014-10-01

Lactoferrin (LF) is an important antimicrobial and immune regulatory protein present in neutrophils and most exocrine secretions of mammals. The antimicrobial activity of LF has been related to the presence of an antimicrobial peptide sequence, called lactoferricin (LFcin), located in the N-terminal region of the protein. The antimicrobial activity of bovine LFcin is considerably stronger than the human version. In this work, chimera peptides combining segments of bovine and human LFcin were generated in order to study their antimicrobial activity and mechanism of action. In addition, the relevance of the conserved disulfide bridge and the resulting cyclic structure of both LFcins were analyzed by using "click chemistry" and sortase A-catalyzed cyclization of the peptides. The N-terminal region of bovine LFcin (residues 17-25 of bovine LF) proved to be very important for the antimicrobial activity of the chimera peptides against E. coli, when combined with the C-terminal region of human LFcin. Similarly the cyclic bovine LFcin analogs generated by "click chemistry" and sortase A preserved the antimicrobial activity of the original peptide, showing the significance of these two techniques in the design of cyclic antimicrobial peptides. The mechanism of action of bovine LFcin and its active derived peptides was strongly correlated with membrane leakage in E. coli and up to some extent with the ability to induce vesicle aggregation. This mechanism was also preserved under conditions of high ionic strength (150 mM NaCl) illustrating the importance of these peptides in a more physiologically relevant system.

Formation of germline chimera Gaok chicken used circulation primordial germ cells (circulation PGCs fresh and thawed

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Kostaman T

2014-03-01

Full Text Available Formation of germline chimeras by transfer of chicken primordial germ cells (PGCs is one of the effective techniques for preservation and regeneration of genetic resources in chickens. This study attempted to form germline chimeras of Gaok chicken buy purifying circulated PGCs of donor embryo before it is transferred to the recipient (White Leghorn chickens=WL and studied the ability of recipient embryo on survival in incubators, and hatchability. This study used 200 fertile eggs of Gaok and 90 fertile WL breed all of the eggs was incubated at 380C and 60% humidity in a portable incubator. PGCs-circulation of the blood collected Gaok embryos at stage 14-16 were taken from the dorsal aorta, and then purified by centrifugation method using nycodenz. PGCs-circulation results further purification frozen in liquid nitrogen before being transferred to the recipient embryo. The results showed that for the development of embryos transferred to the fresh circulation of PGCs-circulation as many as 25 cells can survive up to day 14, while one of the transferred of 50 and 100 cells into recipient embryos was hatched (10%. On the contrari recipient embryos that are transferred to the frozen PGCs-circulation the embryos development was shorter, and only survived until day 10th (treatment 25 cells, day 14th (treatment of 50 cells and day 17th (treatment of 100 cells. It is concluded that the amount of PGCs-circulation embryos transferred to the recipient is one factor that influence the success of the development germline chimeras.

Auxerre. Suivi archéologique du chantier de restauration des toitures de la nef de la cathédrale Saint-Étienne

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Sylvain Aumard

2003-06-01

Full Text Available Le chantierLe chantier de restauration de la cathédrale a commencé en avril 2002 par la toiture de la nef. La mise en place du Conseil scientifique allait permettre de s’intéresser de très près à un terrain un peu nouveau pour le Centre, plutôt habitué à intervenir sur des maçonneries que sur des charpentes et des couvertures. Le déroulement et la teneur du suivi archéologique ont été adaptés à la progression du chantier de restauration, en trois tranches, d’est en ouest. Les observations ont...

Grid adaption using Chimera composite overlapping meshes

Science.gov (United States)

Kao, Kai-Hsiung; Liou, Meng-Sing; Chow, Chuen-Yen

1993-01-01

The objective of this paper is to perform grid adaptation using composite over-lapping meshes in regions of large gradient to capture the salient features accurately during computation. The Chimera grid scheme, a multiple overset mesh technique, is used in combination with a Navier-Stokes solver. The numerical solution is first converged to a steady state based on an initial coarse mesh. Solution-adaptive enhancement is then performed by using a secondary fine grid system which oversets on top of the base grid in the high-gradient region, but without requiring the mesh boundaries to join in any special way. Communications through boundary interfaces between those separated grids are carried out using tri-linear interpolation. Applications to the Euler equations for shock reflections and to a shock wave/boundary layer interaction problem are tested. With the present method, the salient features are well resolved.

Chronic Exposure to Androgenic-Anabolic Steroids Exacerbates Axonal Injury and Microgliosis in the CHIMERA Mouse Model of Repetitive Concussion.

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Dhananjay R Namjoshi

Full Text Available Concussion is a serious health concern. Concussion in athletes is of particular interest with respect to the relationship of concussion exposure to risk of chronic traumatic encephalopathy (CTE, a neurodegenerative condition associated with altered cognitive and psychiatric functions and profound tauopathy. However, much remains to be learned about factors other than cumulative exposure that could influence concussion pathogenesis. Approximately 20% of CTE cases report a history of substance use including androgenic-anabolic steroids (AAS. How acute, chronic, or historical AAS use may affect the vulnerability of the brain to concussion is unknown. We therefore tested whether antecedent AAS exposure in young, male C57Bl/6 mice affects acute behavioral and neuropathological responses to mild traumatic brain injury (TBI induced with the CHIMERA (Closed Head Impact Model of Engineered Rotational Acceleration platform. Male C57Bl/6 mice received either vehicle or a cocktail of three AAS (testosterone, nandrolone and 17α-methyltestosterone from 8-16 weeks of age. At the end of the 7th week of treatment, mice underwent two closed-head TBI or sham procedures spaced 24 h apart using CHIMERA. Post-repetitive TBI (rTBI behavior was assessed for 7 d followed by tissue collection. AAS treatment induced the expected physiological changes including increased body weight, testicular atrophy, aggression and downregulation of brain 5-HT1B receptor expression. rTBI induced behavioral deficits, widespread axonal injury and white matter microgliosis. While AAS treatment did not worsen post-rTBI behavioral changes, AAS-treated mice exhibited significantly exacerbated axonal injury and microgliosis, indicating that AAS exposure can alter neuronal and innate immune responses to concussive TBI.

Chronic Exposure to Androgenic-Anabolic Steroids Exacerbates Axonal Injury and Microgliosis in the CHIMERA Mouse Model of Repetitive Concussion.

Science.gov (United States)

Namjoshi, Dhananjay R; Cheng, Wai Hang; Carr, Michael; Martens, Kris M; Zareyan, Shahab; Wilkinson, Anna; McInnes, Kurt A; Cripton, Peter A; Wellington, Cheryl L

2016-01-01

Concussion is a serious health concern. Concussion in athletes is of particular interest with respect to the relationship of concussion exposure to risk of chronic traumatic encephalopathy (CTE), a neurodegenerative condition associated with altered cognitive and psychiatric functions and profound tauopathy. However, much remains to be learned about factors other than cumulative exposure that could influence concussion pathogenesis. Approximately 20% of CTE cases report a history of substance use including androgenic-anabolic steroids (AAS). How acute, chronic, or historical AAS use may affect the vulnerability of the brain to concussion is unknown. We therefore tested whether antecedent AAS exposure in young, male C57Bl/6 mice affects acute behavioral and neuropathological responses to mild traumatic brain injury (TBI) induced with the CHIMERA (Closed Head Impact Model of Engineered Rotational Acceleration) platform. Male C57Bl/6 mice received either vehicle or a cocktail of three AAS (testosterone, nandrolone and 17α-methyltestosterone) from 8-16 weeks of age. At the end of the 7th week of treatment, mice underwent two closed-head TBI or sham procedures spaced 24 h apart using CHIMERA. Post-repetitive TBI (rTBI) behavior was assessed for 7 d followed by tissue collection. AAS treatment induced the expected physiological changes including increased body weight, testicular atrophy, aggression and downregulation of brain 5-HT1B receptor expression. rTBI induced behavioral deficits, widespread axonal injury and white matter microgliosis. While AAS treatment did not worsen post-rTBI behavioral changes, AAS-treated mice exhibited significantly exacerbated axonal injury and microgliosis, indicating that AAS exposure can alter neuronal and innate immune responses to concussive TBI.

Inhibition of HIV transmission in human cervicovaginal explants and humanized mice using CD4 aptamer-siRNA chimeras

Science.gov (United States)

Wheeler, Lee Adam; Trifonova, Radiana; Vrbanac, Vladimir; Basar, Emre; McKernan, Shannon; Xu, Zhan; Seung, Edward; Deruaz, Maud; Dudek, Tim; Einarsson, Jon Ivar; Yang, Linda; Allen, Todd M.; Luster, Andrew D.; Tager, Andrew M.; Dykxhoorn, Derek M.; Lieberman, Judy

2011-01-01

The continued spread of the HIV epidemic underscores the need to interrupt transmission. One attractive strategy is a topical vaginal microbicide. Sexual transmission of herpes simplex virus type 2 (HSV-2) in mice can be inhibited by intravaginal siRNA application. To overcome the challenges of knocking down gene expression in immune cells susceptible to HIV infection, we used chimeric RNAs composed of an aptamer fused to an siRNA for targeted gene knockdown in cells bearing an aptamer-binding receptor. Here, we showed that CD4 aptamer-siRNA chimeras (CD4-AsiCs) specifically suppress gene expression in CD4+ T cells and macrophages in vitro, in polarized cervicovaginal tissue explants, and in the female genital tract of humanized mice. CD4-AsiCs do not activate lymphocytes or stimulate innate immunity. CD4-AsiCs that knock down HIV genes and/or CCR5 inhibited HIV infection in vitro and in tissue explants. When applied intravaginally to humanized mice, CD4-AsiCs protected against HIV vaginal transmission. Thus, CD4-AsiCs could be used as the active ingredient of a microbicide to prevent HIV sexual transmission. PMID:21576818

Inhibition of muscle-specific gene expression by Id3: requirement of the C-terminal region of the protein for stable expression and function.

Science.gov (United States)

Chen, B; Han, B H; Sun, X H; Lim, R W

1997-01-15

We have examined the role of an Id-like protein, Id3 (also known as HLH462), in the regulation of muscle-specific gene expression. Id proteins are believed to block expression of muscle-specific genes by preventing the dimerization between ubiquitous bHLH proteins (E proteins) and myogenic bHLH proteins such as MyoD. Consistent with its putative role as an inhibitor of differentiation, Id3 mRNA was detected in proliferating skeletal muscle cells, was further induced by basic fibroblast growth factor (bFGF) and was down-regulated in differentiated muscle cultures. Overexpression of Id3 efficiently inhibited the MyoD-mediated activation of the muscle-specific creatine kinase (MCK) reporter gene. Deletion analysis indicated that the C-terminal 15 amino acids of Id3 are critical for the full inhibitory activity while deleting up to 42 residues from the C-terminus of the related protein, Id2, did not affect its ability to inhibit the MCK reporter gene. Chimeric protein containing the N-terminal region of Id3 and the C-terminus of Id2 was also non-functional in transfected cells. In contrast, wild-type Id3, the C-terminal mutants, and the Id3/Id2 chimera could all interact with the E-protein E47in vitro. Additional studies indicated that truncation of the Id3 C-terminus might have adversely affected the expression level of the mutant proteins but the Id3/Id2 chimera was stably expressed. Taken together, our results revealed a more complex requirement for the expression and proper function of the Id family proteins than was hitherto expected.

Newspaper coverage of human-pig chimera research: A qualitative study on select media coverage of scientific breakthrough.

Science.gov (United States)

Hagan-Brown, Abena; Favaretto, Maddalena; Borry, Pascal

2017-07-01

A recently published article in the journal Cell by scientists from the Salk Institute highlighted the successful integration of stem cells from humans in pig embryos. This marks the first step toward the goal of growing human organs in animals for transplantation. There has, to date, been no research performed on the presentation of this breakthrough in the media. We thus assessed early newspaper coverage of the chimera study, looking into the descriptions as well as the benefits and concerns raised by the study mentioned by newspaper sources. We looked at newspaper coverage of the human-pig chimera study in the two weeks after the publication of the article describing the breakthrough in Cell. This time period spanned from January 26 to February 9, 2017. We used the LexisNexis Academic database and identified articles using the search string "hybrid OR chimera AND pig OR human OR embryo." The relevant articles were analyzed using qualitative content analysis. Two researchers openly coded the articles independently using themes that emerged from the raw texts. Our search yielded 31 unique articles, after extensive screening for relevance and duplicates. Through our analysis, we were able to identify several themes in a majority of the texts. Almost every article gave descriptive information about the chimera experiment with details about the study findings. All of the articles mentioned the benefits of the study, citing both immediate- and long-term goals, which included creating transplantable human organs, disease and drug development, and personalized medicine, among others. Some of the articles highlighted some ethical, social, and health concerns that the study and its future implications pose. Many of the articles also offered reassurances over the concerns brought up by the experiment. Our results appeared to align with similar research performed on the media representation of sensitive scientific news coverage. We also explored the inconsistency between

Xenogeneic chimera-Generated by blastocyst complementation-As a potential unlimited source of recipient-tailored organs.

Science.gov (United States)

Oldani, Graziano; Peloso, Andrea; Lacotte, Stéphanie; Meier, Raphael; Toso, Christian

2017-07-01

Blastocyst complementation refers to the injection of cells into a blastocyst. The technology allows for the creation of chimeric animals, which have the potential to be used as an unlimited source of organ donors. Pluripotent stem cells could be generated from a patient in need of a transplantation and injected into a large animal blastocyst (potentially of a pig), leading to the creation of organ(s) allowing immunosuppression-free transplantation. Various chimera combinations have already been generated, but one of the most recent steps leads to the creation of human-pig chimeras, which could be studied at an embryo stage. Although still far from clinical reality, the potential application is almost unlimited. The present review illustrates the historical steps of intra- and interspecific blastocyst complementation in rodents and large animals, specifically looking at its potential for generation of organ grafts. We also speculate on how it could change transplant indications, on its economic impact, and on the linked ethical concerns. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Present status of the Chimera-Isospin experiment

Energy Technology Data Exchange (ETDEWEB)

Politi, G.; Arena, N.; Cardella, G.; DeFilippo, E.; Lanzano, G.; Nigro, S.L.; Pagano, A.; Papa, M.; Pirrone, S.; Russotto, P. [Catania Univ., INFN (Italy); Alderighi, M.; Sechi, G.; Sperduto, M.L. [Milano Univ., INFN, CNR (Italy); Amorini, F.; Anzalone, A.; Baran, V.; Bonasera, A.; Cavallaro, S.L.; Colonna, M.; Di Toro, M.; LaGuidara, E.; Lanzalone, G.; IaconoManno, M.; Giustolisi, F.; Maiolino, C.; Porto, F.; Rizzo, F.; Trifiro, A.; Trimarchi, M. [Catania Univ., INFN, Lab. Nazionali del Sud (Italy); Auditore, L.; Barna, R.; DePasquale, D. [Messina Univ., INFN (Italy); Berceanu, I.; Petrovici, M.; Pop, A. [Inst. for Physics and Nuclear Engineering, Bucharest (Romania); Blicharska, J.; Grzeszczuk, A.; Kowalski, S.; Zipper, W. [Univ. of Silesia, Inst. of Physics, Katowice (Poland); Borderie, B.; LeNeindre, N.; Rivet, M.F. [Paris-11 Univ., IPN-IN2P3-CNRS, 91 - Orsay (France); Bougault, R. [Caen Univ., LPC-ISMRA (France); Briczycnski, J.; Gawlikowicz, W.; Majka, Z.; Planeta, R. [M. Smoluchowski Inst. of Physics, Jagellonian Univ., Cracow (Poland); Bruno, M.; D' Agostino, M.; Fuschini, E.; Geraci, E.; Vannini, G. [Bologna Univ., INFN (Italy); Chatterjee, M.B. [Saha Inst. of Nuclear Physics, NIS Div., Kolkata (India); Chbihi, A.; Wieleczko, J.P. [GANIL -CEA-IN2P3-CNRS, 14 - Caen (France); Cibor, J. [H.Niewodniczanski Inst. of Nuclear Physics, Cracow (Poland); Dayras, R. [CEA Saclay, Dept. d' Astrophysique, de Physique des Particules, de Physique Nucleaire et de l' Instrumentation Associee, SPhN, 91- Gif sur Yvette (France); Guazzoni, P.; Russo, S.; Sassi, M.; Zetta, L. [Milano Univ., INFN (Italy); Guinet, D. [Univ. Claude Bernard, IPN-IN2P3-CNRS, 69 - Lyon (France); Li, S.; Wu, H.; Xiao, Z. [Inst. of Modern Physics, Lanzhou (China); Nicolis, N.G. [Ioannina Univ., Dept. of Physics (Greece); Piasecki, E.; Swiderski, L.; Siwek-Wilczynska, K.; Skwira, I. [Warsaw Univ., Inst. for Experimental Physics (Poland); Rosato, E.; Vigilante, M.; Wilczynski, J.

2003-07-01

The CHIMERA detector was designed to significantly contribute to multifragmentation studies in the field of heavy ion collisions at intermediate energies. The device has been used at 'Laboratori Nazionali del Sud' (LNS) in Catania (Italy) to study different aspects of the relevant nuclear reaction mechanism, in two different campaigns: the first one in 2000, by using the forward part (1 - 30 degrees) of the device, and the second one in 2003, by using the 4{pi} geometry. The experimental results have confirmed the capability of the apparatus for good isotopic identification of light charged particles and light fragments (3

Present status of the Chimera-Isospin experiment

International Nuclear Information System (INIS)

Politi, G.; Arena, N.; Cardella, G.; DeFilippo, E.; Lanzano, G.; Nigro, S.L.; Pagano, A.; Papa, M.; Pirrone, S.; Russotto, P.; Alderighi, M.; Sechi, G.; Sperduto, M.L.; Amorini, F.; Anzalone, A.; Baran, V.; Bonasera, A.; Cavallaro, S.L.; Colonna, M.; Di Toro, M.; LaGuidara, E.; Lanzalone, G.; IaconoManno, M.; Giustolisi, F.; Maiolino, C.; Porto, F.; Rizzo, F.; Trifiro, A.; Trimarchi, M.; Auditore, L.; Barna, R.; DePasquale, D.; Berceanu, I.; Petrovici, M.; Pop, A.; Blicharska, J.; Grzeszczuk, A.; Kowalski, S.; Zipper, W.; Borderie, B.; LeNeindre, N.; Rivet, M.F.; Bougault, R.; Briczycnski, J.; Gawlikowicz, W.; Majka, Z.; Planeta, R.; Bruno, M.; D'Agostino, M.; Fuschini, E.; Geraci, E.; Vannini, G.; Chatterjee, M.B.; Chbihi, A.; Wieleczko, J.P.; Cibor, J.; Dayras, R.; Guazzoni, P.; Russo, S.; Sassi, M.; Zetta, L.; Guinet, D.; Li, S.; Wu, H.; Xiao, Z.; Nicolis, N.G.; Piasecki, E.; Swiderski, L.; Rosato, E.; Vigilante, M.; Wilczynski, J.; Siwek-Wilczynska, K.; Skwira, I.

2003-01-01

The CHIMERA detector was designed to significantly contribute to multifragmentation studies in the field of heavy ion collisions at intermediate energies. The device has been used at 'Laboratori Nazionali del Sud' (LNS) in Catania (Italy) to study different aspects of the relevant nuclear reaction mechanism, in two different campaigns: the first one in 2000, by using the forward part (1 - 30 degrees) of the device, and the second one in 2003, by using the 4π geometry. The experimental results have confirmed the capability of the apparatus for good isotopic identification of light charged particles and light fragments (3< Z<10) in a wide angular detection range. The data analysis relative to the first 2000 campaign (REVERSE) is presently aimed to disentangle dynamical and equilibrium emission components in multifragmentation reactions and to learn more about the role of the isospin degree of freedom in asymmetric nuclear matter. Reduction of the data of the second campaign is still in progress. (authors)

Application of the Chimera overlapped grid scheme to simulation of Space Shuttle ascent flows

Science.gov (United States)

Buning, Pieter G.; Parks, Steven J.; Chan, William M.; Renze, Kevin J.

1992-01-01

Several issues relating to the application of Chimera overlapped grids to complex geometries and flowfields are discussed. These include the addition of geometric components with different grid topologies, gridding for intersecting pieces of geometry, and turbulence modeling in grid overlap regions. Sample results are presented for transonic flow about the Space Shuttle launch vehicle. Comparisons with wind tunnel and flight measured pressures are shown.

The HIV-1 Tat protein modulates CD4 expression in human T cells through the induction of miR-222.

Science.gov (United States)

Orecchini, Elisa; Doria, Margherita; Michienzi, Alessandro; Giuliani, Erica; Vassena, Lia; Ciafrè, Silvia Anna; Farace, Maria Giulia; Galardi, Silvia

2014-01-01

Several cellular microRNAs show substantial changes in expression during HIV-1 infection and their active role in the viral life cycle is progressively emerging. In the present study, we found that HIV-1 infection of Jurkat T cells significantly induces the expression of miR-222. We show that this induction depends on HIV-1 Tat protein, which is able to increase the transcriptional activity of NFkB on miR-222 promoter. Moreover, we demonstrate that miR-222 directly targets CD4, a key receptor for HIV-1, thus reducing its expression. We propose that Tat, by inducing miR-222 expression, complements the CD4 downregulation activity exerted by other viral proteins (i.e., Nef, Vpu, and Env), and we suggest that this represents a novel mechanism through which HIV-1 efficiently represses CD4 expression in infected cells.

Selective elimination of HIV-1-infected cells by Env-directed, HIV-1-based virus-like particles

International Nuclear Information System (INIS)

Peretti, Silvia; Schiavoni, Ilaria; Pugliese, Katherina; Federico, Maurizio

2006-01-01

We recently showed that both replicating and resting cells cultivated with ganciclovir (GCV) were killed when challenged with vesicular stomatitis virus G glycoprotein pseudotyped HIV-1-based virus-like particles (VLPs) carrying the Nef7 (i.e., an HIV-1 Nef mutant incorporating in virions at high levels)/herpes simplex virus-1 thymidine kinase (HSV-TK) fusion product. On this basis, a novel anti-HIV therapeutic approach based on Nef7/TK VLPs expressing X4 or R5 HIV cell receptor complexes has been attempted. We here report that (CD4-CXCR4) and (CD4-CCR5) Nef7-based VLPs efficiently enter cells infected by X4- or R5-tropic HIV-1 strains, respectively. Importantly, the delivery of the VLP-associated Nef7/TK led to cell death upon GCV treatment. Of interest, VLPs were effective also against non-replicating, HIV-1-infected primary human monocyte-derived macrophages. HIV-targeted VLPs represent a promising candidate for the treatment of persistently HIV-1-infected cells that are part of virus reservoirs resistant to HAART therapies

Colon cancer chemoprevention by a novel NO chimera that shows anti-inflammatory and antiproliferative activity in vitro and in vivo.

Science.gov (United States)

Hagos, Ghenet K; Carroll, Robert E; Kouznetsova, Tatiana; Li, Qian; Toader, Violeta; Fernandez, Patricia A; Swanson, Steven M; Thatcher, Gregory R J

2007-08-01

Chemopreventive agents in colorectal cancer possess either antiproliferative or anti-inflammatory actions. Nonsteroidal anti-inflammatory drugs (NSAID) and cyclooxygenase-2 inhibitors have shown promise, but are compromised by side effects. Nitric oxide donor NSAIDs are organic nitrates conjugated via a labile linker to an NSAID, originally designed for use in pain relief, that have shown efficacy in colorectal cancer chemoprevention. The NO chimera, GT-094, is a novel nitrate containing an NSAID and disulfide pharmacophores, a lead compound for the design of agents specifically for colorectal cancer. GT-094 is the first nitrate reported to reduce aberrant crypt foci (by 45%) when administered after carcinogen in the standard azoxymethane rat model of colorectal cancer. Analysis of proximal and distal colon tissue from 8- and 28-week rat/azoxymethane studies showed that GT-094 treatment reduced colon crypt proliferation by 30% to 69%, reduced inducible NO synthase (iNOS) levels by 33% to 67%, reduced poly(ADP-ribose)polymerase-1 expression and cleavage 2- to 4-fold, and elevated levels of p27 in the distal colon 3-fold. Studies in cancer cell cultures recapitulated actions of GT-094: antiproliferative activity and transient G(2)-M phase cell cycle block were measured in Caco-2 cells; apoptotic activity was examined but not observed; anti-inflammatory activity was seen in the inhibition of up-regulation of iNOS and endogenous NO production in lipopolysaccharide (LPS)-induced RAW 264.7 cells. In summary, antiproliferative, anti-inflammatory, and cytoprotective activity observed in vivo and in vitro support GT-094 as a lead compound for the design of NO chimeras for colorectal cancer chemoprevention.

Impact of hyperbolicity on chimera states in ensembles of nonlocally coupled chaotic oscillators

Energy Technology Data Exchange (ETDEWEB)

Semenova, N.; Anishchenko, V. [Department of Physics, Saratov State University, Astrakhanskaya Str. 83, 410012 Saratov (Russian Federation); Zakharova, A.; Schöll, E. [Institut für Theoretische Physik, TU Berlin, Hardenbergstraße 36, 10623 Berlin (Germany)

2016-06-08

In this work we analyse nonlocally coupled networks of identical chaotic oscillators. We study both time-discrete and time-continuous systems (Henon map, Lozi map, Lorenz system). We hypothesize that chimera states, in which spatial domains of coherent (synchronous) and incoherent (desynchronized) dynamics coexist, can be obtained only in networks of chaotic non-hyperbolic systems and cannot be found in networks of hyperbolic systems. This hypothesis is supported by numerical simulations for hyperbolic and non-hyperbolic cases.

Histogenesis of mouse sarcomas induced by implantation of polyvinyl chloride film in radiation chimeras

International Nuclear Information System (INIS)

Mojzhess, T.G.; Prigozhina, E.L.

1976-01-01

Sarcomas were induced in CBA/CBA-T6T6 mouse radiation chimeras by implantation of polyvinyl chloride film subcutaneously 13 months after irradiation and injection of donor's bone marrow. Of the 12 tumors studied 11 had the recipient's karyotype and one the donor's. The formation of connective-tissue cells from bone-marrow precursors thus, evidently does not play an essential role in the histogenesis of sarcomas induced by plastics

Compartmentalization of the gut viral reservoir in HIV-1 infected patients

Directory of Open Access Journals (Sweden)

Grant Tannika

2007-12-01

Full Text Available Abstract Background Recently there has been an increasing interest and appreciation for the gut as both a viral reservoir as well as an important host-pathogen interface in human immunodefiency virus type 1 (HIV-1 infection. The gut associated lymphoid tissue (GALT is the largest lymphoid organ infected by HIV-1. In this study we examined if different HIV-1 quasispecies are found in different parts of the gut of HIV-1 infected individuals. Results Gut biopsies (esophagus, stomach, duodenum and colorectum were obtained from eight HIV-1 infected preHAART (highly active antiretroviral therapy patients. HIV-1 Nef and Reverse transcriptase (RT encoding sequences were obtained through nested PCR amplification from DNA isolated from the gut biopsy tissues. The PCR fragments were cloned and sequenced. The resulting sequences were subjected to various phylogenetic analyses. Expression of the nef gene and viral RNA in the different gut tissues was determined using real-time RT-PCR. Phylogenetic analysis of the Nef protein-encoding region revealed compartmentalization of viral replication in the gut within patients. Viral diversity in both the Nef and RT encoding region varied in different parts of the gut. Moreover, increased nef gene expression (p Conclusion Our results indicated that different HIV-1 quasispecies populate different parts of the gut, and that viral replication in the gut is compartmentalized. These observations underscore the importance of the gut as a host-pathogen interface in HIV-1 infection.

Clonal deletion: A mechanism of tolerance in mixed bone marrow chimeras

International Nuclear Information System (INIS)

Yu, J.C.; Webster, M.; Fox, I.J.

1990-01-01

The mechanism of antigen-specific immunologic unresponsiveness which results from lethal irradiation and mixed (syngeneic-allogeneic) bone marrow cell (BMC) reconstitution is unknown. To determine whether clonal deletion is the mechanism of tolerance in this model, monoclonal antibody (Mab) RR-4-4, specific for a T-cell receptor (V beta 6) reactive against the minor alloantigen MLsa, was employed. Six-week-old B10 mice (H-2b, Mlsb, Thyl.2) were tolerized to AKR antigens (H-2k, Mlsa, Thyl.1) by whole body irradiation (950 R) and iv infusion of T-cell-depleted (TCD) B10 BMC + non-TCD AKR BMC. Chimerism and antigen-specific tolerance were documented by flow microfluorometry (FMF), skin grafting, mixed lymphocyte reaction, and cell-mediated lympholysis. When tolerant B10 mice (n = 15) had accepted AKR skin grafts for greater than 100 days, these animals were studied for the presence of host V beta 6+ T cells using Mab RR-4-4. FMF revealed that 0-5% of host (B10) lymph node and spleen cells from chimeras were V beta 6+ while 15-20% of lymph node and spleen cells from control B10 mice expressed V beta 6. These data demonstrate that clonal deletion occurs in the lethal irradiation-mixed reconstitution model as evidenced by the near total elimination of Mlsa-reactive V beta 6+ T cells and suggest that it maybe a mechanism responsible for tolerance in adult mice

Early dominance of irradiated host cells in the responder profiles of thymocytes from P → F1 radiation chimeras

International Nuclear Information System (INIS)

Korngold, R.; Bennink, J.R.; Doherty, P.C.

1981-01-01

The number of cells in the thymus of radiation (1000 rad) chimeras increases approximately 10-fold between 7 and 14 days after reconstitution with bone marrow. At least 50% of the cells in thymus on day 14 are of host origin and respond to virus presented in the context of both H-2/sup k/ and H-2/sup b/ when primed in irradiated, virus-infected (b x k)F 1 recipients. Strong CTL responses can be generated from thymocytes of donor origin on day 21. All evidence of a significant host thymocyte component has disappeared by day 28. The responsiveness of 14-day thymocytes is not abrogated by pretreatment of the mice used to make the chimeras with anti-thymocyte serum or by using doses of irradiation as high as 1200 rads to eliminate host components

The ChimERA project: Coupling mechanistic exposure and effect models into an integrated platform for ecological risk assessment

NARCIS (Netherlands)

Laender, de F.; Brink, van den P.J.; Janssen, C.R.; Guardo, Di A.

2014-01-01

Current techniques for the ecological risk assessment of chemical substances are often criticised for their lack of environmental realism, ecological relevance and methodological accuracy. ChimERA is a 3-year project (2013-2016), funded by Cefic's Long Range Initiative (LRI) that aims to address

Optimization of three-dimensional imaging on in vitro produced porcine blastocysts and chimeras for stem cell testing

DEFF Research Database (Denmark)

Secher, Jan Ole Bertelsen; Freude, Kristine; Li, Rong

2015-01-01

. This is relevant for testing of presumed pluripotent stem cells. The gold standard for pluripotent stem cells is to test if the cells are capable of contributing to germline chimeras. Differential staining can be used to evaluate the possibility of chimeric contribution; if the cells are located in the area...

In vitro neoformation of grape chimeras (Vitis vinifera L.

Directory of Open Access Journals (Sweden)

Sandrine Verdisson

1999-03-01

Full Text Available Difference in grape sensitivity to Botrytis cinerea attacks between cultivars was explained by differences in the epidermic tissue of the fruit. Therefore, this work was conducted to create a grape periclinal chimera, whose fruits would combine the skin of a Botrytis tolerant cultivar with a pulp of an another cultivar admitted its good organoleptic quality and productivity. In a first time, graftings of two cultivars (Chardonnay and Pinot noir were conducted in vitro on 5 different media supplemented with various plant growth regulators. Adventitious shoots were only observed on medium containing BAP and GA3 from a mixed callus structure after four weeks of darkness followed by a light/dark regime. In a second time, RAPD analysis, conducted on these plants, showed their chimerical characteristics.

Radiation-induced mouse chimeras: a cellular analysis of the major lymphoid compartments, factors affecting lethal graft versus host disease and host-tumor interactions

International Nuclear Information System (INIS)

Almaraz, R.

1981-01-01

The major lymphoid compartments of allogeneic bone marrow chimeras were evaluated for the extent of cell chimerism and distribution of Thy 1 and la bearing cells. These chimeras contained lymphoid cell primarily of donor origin. The bone marrow compartment was a mixture of host and donor origin cells. The distribution of Thy 1 and la bearing cells was similar as in normal mice. The effect of adult thymectomy alone or followed by whole-body irradiation and bone marrow reconstitution on the distribution of the Thy 1 positive cells was also investigated. Thymectomy with or without WBI and bone marrow reconstitution significantly lowered the number of Thy 1 bearing cells in the blood and spleen. The number of la bearing cells did not appear to be affected by thymectomy. The role of circulating lymphoid cells in the incidence of lethal graft versus host disease (GVHD) in radiation induced fully allogeneic mouse chimeras was studied. Mice reconstituted with allogeneic bone marrow from bled donors had a statistically lower incidence of GVHD than those reconstituted with bone marrow from unbled donors. Addition of mature peripheral lymphocytes from blood to the reconstituting bone marrow cells from bled donors reduplicated the high incidence of lethal GVHD. It was demonstrated that the bone marrow of mice not exsanguinated prior to harvesting of bone marrow contained significant numbers of peripheral contaminating cells in the harvested bone marrow. The role of suppressor cell elimination in resisting tumor growth was investigated using radiation induced mouse chimeras. Local effects of irradiation alone at the site of tumor inoculation could account for this lack of growth

Mass and charge identification of fragments detected with the Chimera Silicon-CsI(Tl) telescopes

Energy Technology Data Exchange (ETDEWEB)

Le Neindre, N.; Alderighi, M.; Anzalone, A.; Barna, R.; Bartolucci, M.; Berceanu, I.; Borderie, B.; Bougault, R.; Bruno, M.; Cardella, G.; Cavallaro, S.; D' Agostino, M. E-mail: dagostino@bo.infn.it; Dayras, R.; De Filippo, E.; De Pasquale, D.; Geraci, E.; Giustolisi, F.; Grzeszczuk, A.; Guazzoni, P.; Guinet, D.; Iacono-Manno, M.; Italiano, A.; Kowalski, S.; Lanchais, A.; Lanzano, G.; Lanzalone, G.; Li, S.; Lo Nigro, S.; Maiolino, C.; Manfredi, G.; Moisa, D.; Pagano, A.; Papa, M.; Paduszynski, T.; Petrovici, M.; Piasecki, E.; Pirrone, S.; Politi, G.; Pop, A.; Porto, F.; Rivet, M.F.; Rosato, E.; Russo, S.; Sambataro, S.; Sechi, G.; Simion, V.; Sperduto, M.L.; Steckmeyer, J.C.; Sutera, C.; Trifiro, A.; Tassan-Got, L.; Trimarchi, M.; Vannini, G.; Vigilante, M.; Wilczynski, J.; Wu, H.; Xiao, Z.; Zetta, L.; Zipper, W

2002-09-01

Mass and charge identification of charged products detected with Silicon-CsI(Tl) telescopes of the Chimera apparatus are presented. An identification function, based on the Bethe-Bloch formula, is used to fit empirical correlations between {delta}E and E ADC readings, in order to determine, event by event, the atomic and mass numbers of the detected charged reaction products prior to energy calibration.

Expression of antigens coded in murine leukemia viruses on thymocytes of allogeneic donor origin in AKR mice following syngeneic or allogeneic bone marrow transplantation

International Nuclear Information System (INIS)

Wustrow, T.P.; Good, R.A.

1985-01-01

Removal of T-lymphocytes from marrow inoculum with monoclonal antibody plus complement permitted establishment of long-lived allogeneic chimeras between C57BL/6 and AKR/J mice. Development of leukemia was prevented for 15 mo. Protection from leukemia occurred with both young (4 wk) and older (4 mo) recipients. AKR mice reconstituted with syngeneic marrow or control AKR mice all developed leukemia-lymphoma before 1 yr of age. During spontaneous lymphomagenesis in AKR mice, amplified expression of gag or env gene-coded virus antigens on the surface of thymocytes preceded leukemia development and evidence for amplification of other virus genes. These changes generally appeared before 6 mo. Similar viral gene expression and viral gene amplification occurred in the thymus and spleen cells of leukemia-resistant chimeric mice. Using monoclonal antibodies to Mr 70,000 glycoprotein epitopes characteristic of ecotropic, xenotropic, or dualtropic viruses, antigens marking each virus form were found on thymocytes of allogeneic 4-wk and 4-mo chimeras as well as on the cells of AKR mice and of AKR mice reconstituted with syngeneic marrow. Flow cytometric analysis showed amplification of the virus genes in mice protected from leukemia-lymphoma by allogeneic bone marrow transplantation from leukemia-resistant mice. Allogeneic chimeras and syngeneically transplanted mice both showed evidence of accelerated viremia and of recombinant virus formation. The findings suggest that an event essential to leukemogenesis which occurs within the AKR lymphoid cells or their environment is lacking in the allogeneic chimeras. The nature of this influence of a resistance gene or genes introduced into AKR mice by allogeneic bone marrow transplantation deserves further study

The HIV-1 Tat protein modulates CD4 expression in human T cells through the induction of miR-222

Science.gov (United States)

Orecchini, Elisa; Doria, Margherita; Michienzi, Alessandro; Giuliani, Erica; Vassena, Lia; Ciafrè, Silvia Anna; Farace, Maria Giulia; Galardi, Silvia

2014-01-01

Several cellular microRNAs show substantial changes in expression during HIV-1 infection and their active role in the viral life cycle is progressively emerging. In the present study, we found that HIV-1 infection of Jurkat T cells significantly induces the expression of miR-222. We show that this induction depends on HIV-1 Tat protein, which is able to increase the transcriptional activity of NFkB on miR-222 promoter. Moreover, we demonstrate that miR-222 directly targets CD4, a key receptor for HIV-1, thus reducing its expression. We propose that Tat, by inducing miR-222 expression, complements the CD4 downregulation activity exerted by other viral proteins (i.e., Nef, Vpu, and Env), and we suggest that this represents a novel mechanism through which HIV-1 efficiently represses CD4 expression in infected cells. PMID:24717285

Autoantibody detection in type 2 autoimmune hepatitis using a chimera recombinant protein.

Science.gov (United States)

Vitozzi, Susana; Lapierre, Pascal; Djilali-Saiah, Idriss; Alvarez, Fernando

2002-04-01

Autoantibodies against cytochrome P450 2D6 (CYP2D6), known as anti-liver/kidney microsome type 1 (LKM1) and/or anti-human formiminotransferase cyclodeaminase, formally known as anti-liver cytosol type 1 (LC1) define type 2 autoimmune hepatitis (AIH). The aims of this work are to develop a sensitive and specific test to detect anti-LKM1 and/or anti-LC1 autoantibodies and to establish the prevalence of anti-LC1. Sera from children with type 2 AIH (n=48) and those from a control group (n=100) were evaluated for anti-LKM1 and anti-LC1 by Enzyme-Linked Immunosorbent Assay (ELISA) and Western blotting. Each serum sample was assayed for reactivity against formiminotransferase cyclodeaminase and CYP2D6 alone or as part of a recombinant chimera protein. By ELISA with recombinant chimera protein, 50 serum samples were positive, 48 from patients with type 2 AIH and 2 from patients with chronic hepatitis C. Twenty-five of 48 (52%) patients studied were positive for both CYP2D6 and LC1 autoantibodies. Anti-LC1, either as the only marker or associated with anti-LKM1, was positive in 34/48 (71%). By Western blotting, anti-LC1 was found in 27/48 (56%) patients. This ELISA technique has proven to be antigen-specific and more sensitive than Western blot for the detection of anti-LC1 and anti-LKM1 autoantibodies. The prevalence of anti-LC1 (71%) confirms it as an important immunomarker in type 2 AIH.

La charpente de la nef de la cathédrale de Bourges The structure of the nave in Bourges cathedral

Directory of Open Access Journals (Sweden)

Frédéric Epaud

2012-03-01

Full Text Available La cathédrale gothique de Bourges a été édifiée en deux campagnes avec le chœur, de 1195 à 1214, puis la nef, de 1225 à 1255, après 10 ans d’interruption du chantier. Ses charpentes d’origine ont été en partie reconstruites sur l’ensemble des collatéraux, suite à un incendie en 1559, et sur la partie médiane du grand vaisseau, entre 1747 et 1754, du fait de la suppression du faux transept et de sa flèche. Le relevé archéologique de la charpente gothique subsistante sur la nef, et l’analyse dendrochronologique de ses bois démontrent que les abattages se sont étalés de 1230 à 1257, avec deux grandes campagnes de coupes de bois entre 1240 et 1244 et en automne-hiver 1254-1255, juste avant la mise en œuvre et le levage de la charpente en 1256 ou peu après. Ces coupes successives supposent un approvisionnement du chantier par des donations de bois ou de parcelles forestières exploitées aussitôt, obligeant à un stockage des bois dans l’attente du chantier. La charpente à chevrons-formant-fermes a été exécutée selon un premier projet qui a été modifié en cours de réalisation pour y insérer un dispositif de contreventement longitudinal, avec une nouvelle structure des fermes principales permettant de le recevoir. Ce contreventement axial est doublé par un second situé dans le plan des chevrons, attesté pour la première fois par la dendrochronologie du milieu du xiiie s. En 1262, les travées orientales de la charpente de la nef sont reprises pour permettre le rajout d’une flèche en bois et d’un faux-transept à l’aplomb de la quatrième travée de voûtes.The Gothic cathedral of Bourges was built in two phases, with the chancel from 1195 to 1214 then the nave from 1225 to 1255, after a 10-year interruption to the building work. The original roof structure was in part reconstructed on all the sides, following a fire in 1559, and on the middle part of the great nave, between 1747 and 1754, due to

Niemann-Pick C1 (NPC1/NPC1-like1 Chimeras Define Sequences Critical for NPC1’s Function as a Filovirus Entry Receptor

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Esther Ndungo

2012-10-01

Full Text Available We recently demonstrated that Niemann-Pick C1 (NPC1, a ubiquitous 13-pass cellular membrane protein involved in lysosomal cholesterol transport, is a critical entry receptor for filoviruses. Here we show that Niemann-Pick C1-like1 (NPC1L1, an NPC1 paralog and hepatitis C virus entry factor, lacks filovirus receptor activity. We exploited the structural similarity between NPC1 and NPC1L1 to construct and analyze a panel of chimeras in which NPC1L1 sequences were replaced with cognate sequences from NPC1. Only one chimera, NPC1L1 containing the second luminal domain (C of NPC1 in place of its own, bound to the viral glycoprotein, GP. This engineered protein mediated authentic filovirus infection nearly as well as wild-type NPC1, and more efficiently than did a minimal NPC1 domain C-based receptor recently described by us. A reciprocal chimera, NPC1 containing NPC1L1’s domain C, was completely inactive. Remarkably, an intra-domain NPC1L1-NPC1 chimera bearing only a ~130-amino acid N–terminal region of NPC1 domain C could confer substantial viral receptor activity on NPC1L1. Taken together, these findings account for the failure of NPC1L1 to serve as a filovirus receptor, highlight the central role of the luminal domain C of NPC1 in filovirus entry, and reveal the direct involvement of N–terminal domain C sequences in NPC1’s function as a filovirus receptor.

Multidimensional simulations of core-collapse supernovae with CHIMERA

Science.gov (United States)

Lentz, Eric J.; Bruenn, S. W.; Yakunin, K.; Endeve, E.; Blondin, J. M.; Harris, J. A.; Hix, W. R.; Marronetti, P.; Messer, O. B.; Mezzacappa, A.

2014-01-01

Core-collapse supernovae are driven by a multidimensional neutrino radiation hydrodynamic (RHD) engine, and full simulation requires at least axisymmetric (2D) and ultimately symmetry-free 3D RHD simulation. We present recent and ongoing work with our multidimensional RHD supernova code CHIMERA to understand the nature of the core-collapse explosion mechanism and its consequences. Recently completed simulations of 12-25 solar mass progenitors(Woosley & Heger 2007) in well resolved (0.7 degrees in latitude) 2D simulations exhibit robust explosions meeting the observationally expected explosion energy. We examine the role of hydrodynamic instabilities (standing accretion shock instability, neutrino driven convection, etc.) on the explosion dynamics and the development of the explosion energy. Ongoing 3D and 2D simulations examine the role that simulation resolution and the removal of the imposed axisymmetry have in the triggering and development of an explosion from stellar core collapse. Companion posters will explore the gravitational wave signals (Yakunin et al.) and nucleosynthesis (Harris et al.) of our simulations.

The Crystal Structure of a Maxi/Mini-Ferritin Chimera Reveals Guiding Principles for the Assembly of Protein Cages

Energy Technology Data Exchange (ETDEWEB)

Cornell, Thomas A. [Department; Division; Srivastava, Yogesh [Genome; Jauch, Ralf [Genome Institute of Singapore, Singapore; Genome; Fan, Rongli [Division; Orner, Brendan P. [Department; Division

2017-07-19

Cage proteins assemble into nanoscale structures with large central cavities. They play roles, including those as virus capsids and chaperones, and have been applied to drug delivery and nanomaterials. Furthermore, protein cages have been used as model systems to understand and design protein quaternary structure. Ferritins are ubiquitous protein cages that manage iron homeostasis and oxidative damage. Two ferritin subfamilies have strongly similar tertiary structure yet distinct quaternary structure: maxi-ferritins normally assemble into 24-meric, octahedral cages with C-terminal E-helices centered around 4-fold symmetry axes, and mini-ferritins are 12-meric, tetrahedral cages with 3-fold axes defined by C-termini lacking E-domains. To understand the role E-domains play in ferritin quaternary structure, we previously designed a chimera of a maxi-ferritin E-domain fused to the C-terminus of a mini-ferritin. The chimera is a 12-mer cage midway in size between those of the maxi- and mini-ferritin. The research described herein sets out to understand (a) whether the increase in size over a typical mini-ferritin is due to a frozen state where the E-domain is flipped out of the cage and (b) whether the symmetrical preference of the E-domain in the maxi-ferritin (4-fold axis) overrules the C-terminal preference in the mini-ferritin (3-fold axis). With a 1.99 Å resolution crystal structure, we determined that the chimera assembles into a tetrahedral cage that can be nearly superimposed with the parent mini-ferritin, and that the E-domains are flipped external to the cage at the 3-fold symmetry axes.

On applications of chimera grid schemes to store separation

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Cougherty, F. C.; Benek, J. A.; Steger, J. L.

1985-01-01

A finite difference scheme which uses multiple overset meshes to simulate the aerodynamics of aircraft/store interaction and store separation is described. In this chimera, or multiple mesh, scheme, a complex configuration is mapped using a major grid about the main component of the configuration, and minor overset meshes are used to map each additional component such as a store. As a first step in modeling the aerodynamics of store separation, two dimensional inviscid flow calculations were carried out in which one of the minor meshes is allowed to move with respect to the major grid. Solutions of calibrated two dimensional problems indicate that allowing one mesh to move with respect to another does not adversely affect the time accuracy of an unsteady solution. Steady, inviscid three dimensional computations demonstrate the capability to simulate complex configurations, including closely packed multiple bodies.

Effects of T cell depletion in radiation bone marrow chimeras. II. Requirement for allogeneic T cells in the reconstituting bone marrow inoculum for subsequent resistance to breaking of tolerance

International Nuclear Information System (INIS)

Sykes, M.; Sheard, M.A.; Sachs, D.H.

1988-01-01

The ability of normal recipient-type lymphocytes to break tolerance in long-term allogenic radiation chimeras has been investigated. Reconstitution of lethally irradiated mice with a mixture of syngeneic and allogeneic T cell-depleted (TCD) bone marrow (BM) has previously been shown to lead to mixed chimerism and permanent, specific tolerance to donor and host alloantigen (3-5). If allogeneic T cells are not depleted from the reconstituting inoculum, complete allogeneic chimerism results; however, no clinical evidence for GVHD is observed, presumably due to the protective effect provided by syngeneic TCD BM. This model has now been used to study the effects of allogenic T cells administered in reconstituting BM inocula on stability of long-term tolerance. We have attempted to break tolerance in long-term chimeras originally reconstituted with TCD or non-TCD BM by challenging them with inocula containing normal, nontolerant recipient strain lymphocytes. tolerance was broken with remarkable ease in recipients of mixed marrow inocula in which both original BM components were TCD. In contrast, tolerance in chimeras originally reconstituted with non-TCD allogeneic BM was not affected by such inocula. Susceptibility to loss of chimerism and tolerance was not related to initial levels of chimerism per se, but rather to T cell depletion of allogeneic BM, since chimeras reconstituted with TCD allogeneic BM alone (mean level of allogeneic chimerism 98%) were as susceptible as mixed chimeras to the tolerance-breaking effects of such inocula. The possible contribution of GVH reactivity to this resistance was investigated using an F1 into parent strain combination. In these animals, the use of non-TCD F1 BM inocula for reconstitution did not lead to resistance to the tolerance-breaking effects of recipient strain splenocytes

Major Histocompatibilty Complex-Restricted Adaptive Immune Responses to CT26 Colon Cancer Cell Line in Mixed Allogeneic Chimera.

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Lee, K W; Choi, B; Kim, Y M; Cho, C W; Park, H; Moon, J I; Choi, G-S; Park, J B; Kim, S J

2017-06-01

Although the induction of mixed allogeneic chimera shows promising clinical tolerance results in organ transplantation, its clinical relevance as an anti-cancer therapy is yet unknown. We introduced a mixed allogenic chimera setting with the use of a murine colon cancer cell line, CT26, by performing double bone marrow transplantation. We analyzed donor- and recipient-restricted anti-cancer T-cell responses, and phenotypes of subpopulations of T cells. The protocol involves challenging 1 × 10 5 cells of CT26 cells intra-hepatically on day 50 after bone marrow transplantation, and, by use of CT26 lysates and an H-2L d -restricted AH1 pentamer, flow cytometric analysis was performed to detect the generation of cancer-specific CD4 + and CD8 + T cells at various time points. We found that immunocompetence against tumors depends heavily on cancer-specific CD8 + T-cell responses in a major histocompatibility complex-restricted manner; the evidence was further supported by the increase of interferon-γ-secreting CD4 + T cells. Moreover, we demonstrated that during the effector immune response to CT26 cancer challenge, there was a presence of central memory cells (CD62L hi CCR7 + ) as well as effector memory cells (CD62L lo CCR7 - ). Moreover, mixed allogeneic chimeras (BALB/c to C56BL/6 or vice versa) showed similar or heightened immune responses to CT26 cells compared with that of wild-type mice. Our results suggest that the responses of primary immunocompetency and of pre-existing memory T cells against allogeneic cancer are sustained and preserved long-term in a mixed allogeneic chimeric environment. Copyright © 2017 Elsevier Inc. All rights reserved.

Amplitude mediated chimera states with active and inactive oscillators

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Mukherjee, Rupak; Sen, Abhijit

2018-05-01

The emergence and nature of amplitude mediated chimera states, spatio-temporal patterns of co-existing coherent and incoherent regions, are investigated for a globally coupled system of active and inactive Ginzburg-Landau oscillators. The existence domain of such states is found to shrink and shift in parametric space with the increase in the fraction of inactive oscillators. The role of inactive oscillators is found to be twofold—they get activated to form a separate region of coherent oscillations and, in addition, decrease the common collective frequency of the coherent regions by their presence. The dynamical origin of these effects is delineated through a bifurcation analysis of a reduced model system that is based on a mean field approximation. Our results may have practical implications for the robustness of such states in biological or physical systems where age related deterioration in the functionality of components can occur.

Multitasking for flows about multiple body configurations using the chimera grid scheme

Science.gov (United States)

Dougherty, F. C.; Morgan, R. L.

1987-01-01

The multitasking of a finite-difference scheme using multiple overset meshes is described. In this chimera, or multiple overset mesh approach, a multiple body configuration is mapped using a major grid about the main component of the configuration, with minor overset meshes used to map each additional component. This type of code is well suited to multitasking. Both steady and unsteady two dimensional computations are run on parallel processors on a CRAY-X/MP 48, usually with one mesh per processor. Flow field results are compared with single processor results to demonstrate the feasibility of running multiple mesh codes on parallel processors and to show the increase in efficiency.

Construction of a plasmid coding for green fluorescent protein tagged cathepsin L and data on expression in colorectal carcinoma cells

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Tripti Tamhane

2015-12-01

Full Text Available The endo-lysosomal cysteine cathepsin L has recently been shown to have moonlighting activities in that its unexpected nuclear localization in colorectal carcinoma cells is involved in cell cycle progression (Tamhane et al., 2015 [1]. Here, we show data on the construction and sequence of a plasmid coding for human cathepsin L tagged with an enhanced green fluorescent protein (phCL-EGFP in which the fluorescent protein is covalently attached to the C-terminus of the protease. The plasmid was used for transfection of HCT116 colorectal carcinoma cells, while data from non-transfected and pEGFP-N1-transfected cells is also shown. Immunoblotting data of lysates from non-transfected controls and HCT116 cells transfected with pEGFP-N1 and phCL-EGFP, showed stable expression of cathepsin L-enhanced green fluorescent protein chimeras, while endogenous cathepsin L protein amounts exceed those of hCL-EGFP chimeras. An effect of phCL-EGFP expression on proliferation and metabolic states of HCT116 cells at 24 h post-transfection was observed.

Construction of a novel lentiviral vector carrying human B-domain ...

African Journals Online (AJOL)

USER

2010-03-29

Mar 29, 2010 ... Construction of the lentiviral expression vector. Both self-inactivating (SIN) ..... activated partial thromboplastin time. Figure 4. Expression of ... 1 entry to an endocytic pathway and suppresses both the requirement for Nef and ...

Functional analysis of Kv1.2 and paddle chimera Kv channels in planar lipid bilayers

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Tao, Xiao; MacKinnon, Roderick

2010-01-01

Summary Voltage-dependent K+ channels play key roles in shaping electrical signaling in both excitable as well as non-excitable cells. These channels open and close in response to the voltage changes across the cell membrane. Many studies have been carried out in order to understand the voltage sensing mechanism. Our laboratory recently determined the atomic structures of a mammalian voltage-dependent K+ channel Kv1.2 and a mutant of Kv1.2 named the ‘paddle-chimera’ channel, in which the voltage sensor paddle was transferred from Kv2.1 to Kv1.2. These two structures provide atomic descriptions of voltage-dependent channels with unprecedented clarity. Until now the functional integrity of these two channels biosynthesized in yeast cells have not been assessed. Here we report the electrophysiological and pharmacological properties of Kv1.2 and the paddle chimera channels in planar lipid bilayers. We demonstrate that Pichia yeast produce ‘normally functioning’ mammalian voltage-dependent K+ channels with qualitatively similar features to the Shaker K+ channel in the absence of the N-terminal inactivation gate, and that the paddle chimera mutant channel functions as well as Kv1.2. We find, however, that in several respects the Kv1.2 channel exhibits functional properties that are distinct from Kv1.2 channels reported in the literature. PMID:18638484

Streptococcal cell wall-induced arthritis and adjuvant arthritis in F344----Lewis and in Lewis----F344 bone marrow chimeras

International Nuclear Information System (INIS)

van Bruggen, M.C.; van den Broek, M.F.; van den Berg, W.B.

1991-01-01

Streptococcal cell wall (SCW)-induced arthritis and adjuvant arthritis (AA) are rat models for chronic, erosive polyarthritis. Both models can be induced in susceptible Lewis rats, whereas F344 rats are resistant. In AA as well as in SCW arthritis, antigen-specific T lymphocytes have been demonstrated to be crucial for chronic disease. In this communication the authors describe their studies to probe the cellular mechanism responsible for the difference in susceptibility of Lewis and F344, using bone marrow chimeras. By transplanting bone marrow cells from F344 into lethally irradiated Lewis recipients, Lewis rats were rendered resistant to SCW arthritis induction. F344 rats reconstituted with Lewis bone marrow, i.e., Lewis----F344 chimeras, develop an arthritis upon SCW injection. For AA comparable results were obtained. These data suggest that both resistance and susceptibility to bacterium-induced chronic arthritis are mediated by hemopoietic/immune cells and that the recipiental environment does not influence the susceptibility to chronic joint inflammation

Test of GET Electronics for the CHIMERA and FARCOS multi-detectors

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De Luca, S.; Acosta, L.; Auditore, L.; Boiano, C.; Cardella, G.; Castoldi, A.; D'Andrea, M.; De Filippo, E.; Dell'Aquila, D.; Fichera, F.; Gnoffo, B.; Guazzoni, C.; Lanzalone, G.; Lombardo, I.; Martorana, N. S.; Minniti, T.; Norella, S.; Pagano, A.; Pagano, E. V.; Papa, M.; Pirrone, S.; Politi, G.; Quattrocchi, L.; Rizzo, F.; Russotto, P.; Saccà, G.; Trifirò, A.; Trimarchi, M.; Verde, G.; Vigilante, M.

2017-11-01

In this paper we present the results of the tests on the new digital electronics GET (General Electronics for Tpc), which will be used for the readout of the CsI(Tl) detectors of CHIMERA (Charged Heavy Ion Mass and Energy Resolving Array) and for the new correlator FARCOS (Femtoscope ARray for COrrelations and Spectroscopy). The new electronics allows us to digitize the full waveform of the signals produced by the detector. Among its features it is worth noticing the compactness and low power consumption (5W for 256 channels). Tests have been performed with pulsers, radioactive sources and ion beams. With such electronics very good results in energy resolution and isotope separation of the detected fragments were obtained, by using both hardware and software filters.

Monsters, dreams and madness: Commentary on 'The arms of the chimeras'.

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Reis, Bruce

2016-04-01

Considering Freudian and Post-Freudian approaches to the intersubjective Beatrice Ithier puts the work of Michel de M'Uzan and Thomas Ogden in comparison. To this comparison I add a consideration of the work of Christopher Bollas. The highly creative clinical approaches these three theorists take is shown to be informed by their elaborations of the Freudian notion of unconscious communication and by new approaches to the issue of identity. Attention is paid to differentiating traumatic from fanciful chimeras; and to the experience of the analyst undergoing the sorts of transformations requisite to entering this psychic space marked by fluid exchanges of being and becoming, wherein analyst becomes patient, new subjects are created through shared dreams, and through which monsters appear. Copyright © 2016 Institute of Psychoanalysis.

New type of chimera structures in a ring of bistable FitzHugh-Nagumo oscillators with nonlocal interaction

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Shepelev, I. A.; Vadivasova, T. E.; Bukh, A. V.; Strelkova, G. I.; Anishchenko, V. S.

2017-04-01

We study the spatiotemporal dynamics of a ring of nonlocally coupled FitzHugh-Nagumo oscillators in the bistable regime. A new type of chimera patterns has been found in the noise-free network and when isolated elements do not oscillate. The region of existence of these structures has been explored when the coupling range and the coupling strength between the network elements are varied.

Study on proliferative responses to host Ia antigens in allogeneic bone marrow chimera in mice: sequential analysis of the reactivity and characterization of the cells involved in the responses

International Nuclear Information System (INIS)

Iwabuchi, K.; Ogasawara, K.; Ogasawara, M.; Yasumizu, R.; Noguchi, M.; Geng, L.; Fujita, M.; Good, R.A.; Onoe, K.

1987-01-01

Irradiation bone marrow chimeras were established by reconstitution of lethally irradiated AKR mice with C57BL/10 marrow cells to permit serial analysis of the developing reactivities of lymphocytes from such chimeras, [B10----AKR], against donor, host, or third party antigens. We found that substantial proliferative responses to Ia antigens of the recipient strain and also to third party antigens were generated by the thymocytes obtained from the irradiation chimeras at an early stage after bone marrow reconstitution. The majority of the responding thymocytes had surfaces lacking demonstrable peanut agglutinin receptors and were donor type Thy-1+, Ly-2-, and L3T4+ in both anti-recipient and anti-third party MLR. In anti-host responses, however, Ly-2+ thymocytes seemed to be at least partially involved. This capacity of thymus cells to mount a response to antigens of the recipient strain declined shortly thereafter, whereas the capacity to mount MLR against third party antigens persisted. The spleen cells of [B10----AKR] chimeras at the same time developed a more durable capability to exhibit anti-host reactivities and a permanent capability of reacting to third party allo-antigens. The stimulator antigens were Ia molecules on the stimulator cells in both anti-recipient and anti-third party MLR. The responding splenocytes were of donor origin and most of them had Thy-1+, Ly-1+2-, and L3T4+ phenotype

Mouse immature oocytes irradiated in vivo at 14-days of age and evaluated for transmitted effects using the aggregation embryo chimera assay

International Nuclear Information System (INIS)

Straume, T.; Raabe, O.G.; Walsh, K.J.; Wiley, L.M.

1996-01-01

A previous study using the mouse-preimplantation-embryo-chimera assay demonstrated a reproducible transmitted effect (proliferation disadvantage observed in early embryos) from females irradiated as 49-day-old adults using 0.15 Gy of gamma rays and then mated seven weeks later, i.e., embryos were from oocytes that were immature at time of irradiation. Because mouse immature oocytes are known to be much more radiosensitive to cell killing in juveniles than in adults, a follow-on study was performed here using 14-day-old juvenile mice. In contrast to adults, the exposure of juveniles to 0.15 Gy of gamma rays did not result in a detectable transmitted proliferation disadvantage when animals were mated 7 or 12 weeks later. This observation is discussed in light of previous studies on mouse immature oocytes and embryo chimeras

CHIMERA II - A real-time multiprocessing environment for sensor-based robot control

Science.gov (United States)

Stewart, David B.; Schmitz, Donald E.; Khosla, Pradeep K.

1989-01-01

A multiprocessing environment for a wide variety of sensor-based robot system, providing the flexibility, performance, and UNIX-compatible interface needed for fast development of real-time code is addressed. The requirements imposed on the design of a programming environment for sensor-based robotic control is outlined. The details of the current hardware configuration are presented, along with the details of the CHIMERA II software. Emphasis is placed on the kernel, low-level interboard communication, user interface, extended file system, user-definable and dynamically selectable real-time schedulers, remote process synchronization, and generalized interprocess communication. A possible implementation of a hierarchical control model, the NASA/NBS standard reference model for telerobot control system is demonstrated.

Chimera distribution amplitudes for the pion and the longitudinally polarized ρ-meson

Energy Technology Data Exchange (ETDEWEB)

Stefanis, N.G., E-mail: stefanis@tp2.ruhr-uni-bochum.de [Institut für Theoretische Physik II, Ruhr-Universität Bochum, D-44780 Bochum (Germany); Pimikov, A.V., E-mail: pimikov@theor.jinr.ru [Bogoliubov Laboratory of Theoretical Physics, JINR, 141980 Dubna (Russian Federation); Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, 730000 (China)

2016-01-15

Using QCD sum rules with nonlocal condensates, we show that the distribution amplitude of the longitudinally polarized ρ-meson may have a shorttailed platykurtic profile in close analogy to our recently proposed platykurtic distribution amplitude for the pion. Such a chimera distribution de facto amalgamates the broad unimodal profile of the distribution amplitude, obtained with a Dyson–Schwinger equations-based computational scheme, with the suppressed tails characterizing the bimodal distribution amplitudes derived from QCD sum rules with nonlocal condensates. We argue that pattern formation, emerging from the collective synchronization of coupled oscillators, can provide a single theoretical scaffolding to study unimodal and bimodal distribution amplitudes of light mesons without recourse to particular computational schemes and the reasons for them.

Double-chimera proteins to enhance recruitment of endothelial cells and their progenitor cells.

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Behjati, M; Kazemi, M; Hashemi, M; Zarkesh-Esfahanai, S H; Bahrami, E; Hashemi-Beni, B; Ahmadi, R

2013-08-20

Enhanced attraction of selective vascular reparative cells is of great importance in order to increase vascular patency after endovascular treatments. We aimed to evaluate efficient attachment of endothelial cells and their progenitors on surfaces coated with mixture of specific antibodies, L-selectin and VE-cadherin, with prohibited platelet attachment. The most efficient conditions for coating of L-selectin-Fc chimera and VE-cadherin-Fc chimera proteins were first determined by protein coating on ELISA plates. The whole processes were repeated on titanium substrates, which are commonly used to coat stents. Endothelial progenitor cells (EPCs) and human umbilical vein endothelial cells (HUVECs) were isolated and characterized by flow cytometry. Cell attachment, growth, proliferation, viability and surface cytotoxicity were evaluated using nuclear staining and MTT assay. Platelet and cell attachment were evaluated using scanning electron microscopy. Optimal concentration of each protein for surface coating was 50 ng/ml. The efficacy of protein coating was both heat and pH independent. Calcium ions had significant impact on simultaneous dual-protein coating (P<0.05). Coating stability data revealed more than one year stability for these coated proteins at 4°C. L-selectin and VE-cadherin (ratio of 50:50) coated surface showed highest EPC and HUVEC attachment, viability and proliferation compared to single protein coated and non-coated titanium surfaces (P<0.05). This double coated surface did not show any cytotoxic effect. Surfaces coated with L-selectin and VE-cadherin are friendly surface for EPC and endothelial cell attachment with less platelet attachment. These desirable factors make the L-selectin and VE-cadherin coated surfaces perfect candidate endovascular device. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Identification of Molecular Tumor Markers in Renal Cell Carcinomas with TFE3 Protein Expression by RNA Sequencing

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Dorothee Pflueger

2013-11-01

Full Text Available TFE3 translocation renal cell carcinoma (tRCC is defined by chromosomal translocations involving the TFE3 transcription factor at chromosome Xp11.2. Genetically proven TFE3 tRCCs have a broad histologic spectrum with overlapping features to other renal tumor subtypes. In this study,we aimed for characterizing RCC with TFE3 protein expression. Using next-generation whole transcriptome sequencing (RNA-Seq as a discovery tool, we analyzed fusion transcripts, gene expression profile, and somatic mutations in frozen tissue of one TFE3 tRCC. By applying a computational analysis developed to call chimeric RNA molecules from paired-end RNA-Seq data, we confirmed the known TFE3 translocation. Its fusion partner SFPQ has already been described as fusion partner in tRCCs. In addition, an RNAread-through chimera between TMED6 and COG8 as well as MET and KDR (VEGFR2 point mutations were identified. An EGFR mutation, but no chromosomal rearrangements, was identified in a control group of five clear cell RCCs (ccRCCs. The TFE3 tRCC could be clearly distinguished from the ccRCCs by RNA-Seq gene expression measurements using a previously reported tRCC gene signature. In validation experiments using reverse transcription-PCR, TMED6-COG8 chimera expression was significantly higher in nine TFE3 translocated and six TFE3-expressing/non-translocated RCCs than in 24 ccRCCs (P<.001 and 22 papillaryRCCs (P<.05-.07. Immunohistochemical analysis of selected genes from the tRCC gene signature showed significantly higher eukaryotic translation elongation factor 1 alpha 2 (EEF1A2 and Contactin 3 (CNTN3 expression in 16 TFE3 translocated and six TFE3-expressing/non-translocated RCCs than in over 200 ccRCCs (P < .0001, both.

Persistence of antigen is required to maintain transplantation tolerance induced by genetic modification of bone marrow stem cells.

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Tian, C; Bagley, J; Iacomini, J

2006-09-01

Genetic modification of hematopoietic stem cells (HSCs) resulting in a state of molecular chimerism can be used to induce donor-specific tolerance to allografts. However, the requirements for maintaining tolerance in molecular chimeras remain unknown. Here, we examined whether long-term expression of a retrovirally encoded alloantigen in hematopoietic cells is required to maintain donor-specific tolerance in molecular chimeras. To this end, mice were reconstituted with syngeneic bone marrow transduced with retroviruses carrying the gene encoding the allogeneic MHC class I molecule Kb. Following induction of molecular chimerism, mice were depleted of cells expressing Kb by administration of the anti-Kb monoclonal antibody Y-3. Mice that were effectively depleted of cells expressing the retrovirally encoded MHC class I antigen rejected Kb disparate skin allografts. In contrast, control molecular chimeras accepted Kb disparate skin allografts indefinitely. These data suggest maintenance of tolerance in molecular chimeras requires long-term expression of retrovirally transduced alloantigen on the progeny of retrovirally transduced HSCs.

Self-organized emergence of multilayer structure and chimera states in dynamical networks with adaptive couplings

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Kasatkin, D. V.; Yanchuk, S.; Schöll, E.; Nekorkin, V. I.

2017-12-01

We report the phenomenon of self-organized emergence of hierarchical multilayered structures and chimera states in dynamical networks with adaptive couplings. This process is characterized by a sequential formation of subnetworks (layers) of densely coupled elements, the size of which is ordered in a hierarchical way, and which are weakly coupled between each other. We show that the hierarchical structure causes the decoupling of the subnetworks. Each layer can exhibit either a two-cluster state, a periodic traveling wave, or an incoherent state, and these states can coexist on different scales of subnetwork sizes.

Incomplete development of the spleen and the deformity in the chimeras between asplenic mutant (Dominant hemimelia) and normal mice.

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Suto, J; Wakayama, T; Imamura, K; Goto, S; Fukuta, K

1995-08-01

The semidominant gene Dh (Dominant hemimelia) induces skeletal and visceral abnormalities of various degrees and failure of the spleen in mice. The homozygous individual (Dh/Dh) seems to be lethal. The present experiment was designed to investigate the ability Dh cells to form a spleen and the genesis of the hind limb malformations by Dh/Dh and Dh/+ cells in chimeric mice. The Dh/Dh and Dh/+ embryos were produced in the F2 progeny of a cross between inbred strains of Dh/+ and DDD mice. They were aggregated with C3H/He or C57BL/6 embryos to make chimeras. Identification of Dh/Dh or Dh/+ embryos was carried out by Pep-3, and chimerism was analyzed by Gpi-1. Of 25 chimeras carrying the Dh gene, four mice formed a small spleen, two mice had a vestigial spleen, and the others no spleen. The tissues of the incompletely developed spleens were normal histologically and Dh cells were involved in the tissues of the spleen. In the chimeric mice, hindlimb malformation by the Dh gene was reduced in severity and the lethality of the homozygote (Dh/Dh) was rescued.

Nitrite-embedded packaging film effects on fresh and frozen beef color development and stability as influenced by meat age and muscle type.

Science.gov (United States)

Claus, James R; Du, Chen

2013-11-01

Muscles (Longissimus lumborum, LL; Psoas major, PM, semitendinosus, ST) were aged (2, 9d postmortem), cut into steaks, anaerobically packaged (nitrite-embedded film, NEF), and displayed (fresh, 19d; frozen, 39d). Fresh NEF increased (PMeat age influenced NEF color. Intact NEF maintained acceptable red color throughout display. Residual nitrite and nitrate associated with fresh NEF and nitrate in NEF cooked LL were found (Pmeat age and muscle differences. NEF packaging has potential to extend fresh beef color display life. NEF appears to offer the opportunity to display bright red beef in frozen display by limiting typical effects of photooxidation. Copyright © 2013 Elsevier Ltd. All rights reserved.

Exploiting the yeast L-A viral capsid for the in vivo assembly of chimeric VLPs as platform in vaccine development and foreign protein expression.

Directory of Open Access Journals (Sweden)

Frank Powilleit

Full Text Available A novel expression system based on engineered variants of the yeast (Saccharomyces cerevisiae dsRNA virus L-A was developed allowing the in vivo assembly of chimeric virus-like particles (VLPs as a unique platform for a wide range of applications. We show that polypeptides fused to the viral capsid protein Gag self-assemble into isometric VLP chimeras carrying their cargo inside the capsid, thereby not only effectively preventing proteolytic degradation in the host cell cytosol, but also allowing the expression of a per se cytotoxic protein. Carboxyterminal extension of Gag by T cell epitopes from human cytomegalovirus pp65 resulted in the formation of hybrid VLPs that strongly activated antigen-specific CD8(+ memory T cells ex vivo. Besides being a carrier for polypeptides inducing antigen-specific immune responses in vivo, VLP chimeras were also shown to be effective in the expression and purification of (i a heterologous model protein (GFP, (ii a per se toxic protein (K28 alpha-subunit, and (iii a particle-associated and fully recyclable biotechnologically relevant enzyme (esterase A. Thus, yeast viral Gag represents a unique platform for the in vivo assembly of chimeric VLPs, equally attractive and useful in vaccine development and recombinant protein production.

Accessory genes confer a high replication rate to virulent feline immunodeficiency virus.

Science.gov (United States)

Troyer, Ryan M; Thompson, Jesse; Elder, John H; VandeWoude, Sue

2013-07-01

Feline immunodeficiency virus (FIV) is a lentivirus that causes AIDS in domestic cats, similar to human immunodeficiency virus (HIV)/AIDS in humans. The FIV accessory protein Vif abrogates the inhibition of infection by cat APOBEC3 restriction factors. FIV also encodes a multifunctional OrfA accessory protein that has characteristics similar to HIV Tat, Vpu, Vpr, and Nef. To examine the role of vif and orfA accessory genes in FIV replication and pathogenicity, we generated chimeras between two FIV molecular clones with divergent disease potentials: a highly pathogenic isolate that replicates rapidly in vitro and is associated with significant immunopathology in vivo, FIV-C36 (referred to here as high-virulence FIV [HV-FIV]), and a less-pathogenic strain, FIV-PPR (referred to here as low-virulence FIV [LV-FIV]). Using PCR-driven overlap extension, we produced viruses in which vif, orfA, or both genes from virulent HV-FIV replaced equivalent genes in LV-FIV. The generation of these chimeras is more straightforward in FIV than in primate lentiviruses, since FIV accessory gene open reading frames have very little overlap with other genes. All three chimeric viruses exhibited increased replication kinetics in vitro compared to the replication kinetics of LV-FIV. Chimeras containing HV-Vif or Vif/OrfA had replication rates equivalent to those of the virulent HV-FIV parental virus. Furthermore, small interfering RNA knockdown of feline APOBEC3 genes resulted in equalization of replication rates between LV-FIV and LV-FIV encoding HV-FIV Vif. These findings demonstrate that Vif-APOBEC interactions play a key role in controlling the replication and pathogenicity of this immunodeficiency-inducing virus in its native host species and that accessory genes act as mediators of lentiviral strain-specific virulence.

Latent Membrane Protein 1 as a molecular adjuvant for single-cycle lentiviral vaccines

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Rahmberg Andrew R

2011-05-01

Full Text Available Abstract Background Molecular adjuvants are a promising method to enhance virus-specific immune responses and protect against HIV-1 infection. Immune activation by ligands for receptors such as CD40 can induce dendritic cell activation and maturation. Here we explore the incorporation of two CD40 mimics, Epstein Barr Virus gene LMP1 or an LMP1-CD40 chimera, into a strain of SIV that was engineered to be limited to a single cycle of infection. Results Full length LMP1 or the chimeric protein LMP1-CD40 was cloned into the nef-locus of single-cycle SIV. Human and Macaque monocyte derived macrophages and DC were infected with these viruses. Infected cells were analyzed for activation surface markers by flow cytometry. Cells were also analyzed for secretion of pro-inflammatory cytokines IL-1β, IL-6, IL-8, IL-12p70 and TNF by cytometric bead array. Conclusions Overall, single-cycle SIV expressing LMP1 and LMP1-CD40 produced a broad and potent TH1-biased immune response in human as well as rhesus macaque macrophages and DC when compared with control virus. Single-cycle SIV-LMP1 also enhanced antigen presentation by lentiviral vector vaccines, suggesting that LMP1-mediated immune activation may enhance lentiviral vector vaccines against HIV-1.

THE KEY TO THE TREASURE IS THE TREASURE: BARTH’S METAFICTION IN CHIMERA

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Katarina Drzajic

2014-11-01

Full Text Available John Barth, one of the most prominent postmodern authors, is famous for his creative literary games: while his favorite tool, metafiction, is at times hard to comprehend, he is almost always both the writer and a character of his stories. “Everyone is necessarily the hero of his own life story,” he said, thus confirming the quite loose difference between reality and fiction in post-modernism. Bearing in mind that the story within a story is a common characteristic of his work, in this paper we shall analyze the most interesting points at which we encounter this phenomenon an d discover what actually represents the treasure in one of his most perplexing, yet incredibly captivating novels, Chimera.

Bioassays for TSH Receptor Autoantibodies, from FRTL-5 Cells to TSH Receptor-LH/CG Receptor Chimeras: The Contribution of Leonard D. Kohn.

Science.gov (United States)

Giuliani, Cesidio; Saji, Motoyasu; Bucci, Ines; Napolitano, Giorgio

2016-01-01

Since the discovery 60 years ago of the "long-acting thyroid stimulator" by Adams and Purves, great progress has been made in the detection of thyroid-stimulating hormone (TSH) receptor (TSHR) autoantibodies (TRAbs) in Graves' disease. Today, commercial assays are available that can detect TRAbs with high accuracy and provide diagnostic and prognostic evaluation of patients with Graves' disease. The present review focuses on the development of TRAbs bioassays, and particularly on the role that Leonard D. Kohn had in this. Indeed, 30 years ago, the Kohn group developed a bioassay based on the use of FRTL-5 cells that was characterized by high reproducibility, feasibility, and diagnostic accuracy. Using this FRTL-5 bioassay, Kohn and his colleagues were the first to develop monoclonal antibodies (moAbs) against the TSHR. Furthermore, they demonstrated the multifaceted functional nature of TRAbs in patients with Graves' disease, with the identification of stimulating and blocking TRAbs, and even antibodies that activated pathways other than cAMP. After the cloning of the TSHR, the Kohn laboratory constructed human TSHR-rat luteinizing hormone/chorionic gonadotropin receptor chimeras. This paved the way to a new bioassay based on the use of non-thyroid cells transfected with the Mc4 chimera. The new Mc4 bioassay is characterized by high diagnostic and prognostic accuracy, greater than for other assays. The availability of a commercial kit based on the Mc4 chimera is spreading the use of this assay worldwide, indicating its benefits for these patients with Graves' disease. This review also describes the main contributions made by other researchers in TSHR molecular biology and TRAbs assay, especially with the development of highly potent moAbs. A comparison of the diagnostic accuracies of the main TRAbs assays, as both immunoassays and bioassays, is also provided.

De novo generation of helper virus-satellite chimera RNAs results in disease attenuation and satellite sequence acquisition in a host-dependent manner.

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Pyle, J D; Scholthof, Karen-Beth G

2018-01-15

Panicum mosaic virus (PMV) is a helper RNA virus for satellite RNAs (satRNAs) and a satellite virus (SPMV). Here, we describe modifications that occur at the 3'-end of a satRNA of PMV, satS. Co-infections of PMV+satS result in attenuation of the disease symptoms induced by PMV alone in Brachypodium distachyon and proso millet. The 375 nt satS acquires ~100-200 nts from the 3'-end of PMV during infection and is associated with decreased abundance of the PMV RNA and capsid protein in millet. PMV-satS chimera RNAs were isolated from native infections of St. Augustinegrass and switchgrass. Phylogenetic analyses revealed that the chimeric RNAs clustered according to the host species from which they were isolated. Additionally, the chimera satRNAs acquired non-viral "linker" sequences in a host-specific manner. These results highlight the dynamic regulation of viral pathogenicity by satellites, and the selective host-dependent, sequence-based pressures for driving satRNA generation and genome compositions. Copyright © 2017 Elsevier Inc. All rights reserved.

Ectopic ERK Expression Induces Phenotypic Conversion of C10 Cells and Alters DNA Methyltransferase Expression

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Sontag, Ryan L.; Weber, Thomas J.

2012-05-04

In some model systems constitutive extracellular signal regulated kinase (ERK) activation is sufficient to promote an oncogenic phenotype. Here we investigate whether constitutive ERK expression influences phenotypic conversion in murine C10 type II alveolar epithelial cells. C10 cells were stably transduced with an ERK1-green fluorescent protein (ERK1-GFP) chimera or empty vector and ectopic ERK expression was associated with the acquisition of soft agar focus-forming potential in late passage, but not early passage cells. Late passage ERK1-GFP cells exhibited a significant increase in the expression of DNA methyl transferases (DNMT1 and 3b) and a marked increase in sensitivity to 5-azacytidine (5-azaC)-mediated toxicity, relative to early passage ERK1-GFP cells and vector controls. The expression of xeroderma pigmentosum complementation group A (XPA) and DNA-dependent protein kinase catalytic subunit (DNA-PKcs) were significantly increased in late passage cells, suggesting enhanced DNA damage recognition and repair activity which we interpret as a reflection of genomic instability. Phospho-ERK levels were dramatically decreased in late passage ERK1-GFP cells, relative to early passage and vector controls, and phospho-ERK levels were restored by treatment with sodium orthovanadate, indicating a role for phosphatase activity in this response. Collectively these observations suggest that ectopic ERK expression promotes phenotypic conversion of C10 cells that is associated with latent effects on epigenetic programming and phosphatase activities.

Regulation of expression of two LY-6 family genes by intron retention and transcription induced chimerism

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Mallya Meera

2008-09-01

Full Text Available Abstract Background Regulation of the expression of particular genes can rely on mechanisms that are different from classical transcriptional and translational control. The LY6G5B and LY6G6D genes encode LY-6 domain proteins, whose expression seems to be regulated in an original fashion, consisting of an intron retention event which generates, through an early premature stop codon, a non-coding transcript, preventing expression in most cell lines and tissues. Results The MHC LY-6 non-coding transcripts have shown to be stable and very abundant in the cell, and not subject to Nonsense Mediated Decay (NMD. This retention event appears not to be solely dependent on intron features, because in the case of LY6G5B, when the intron is inserted in the artificial context of a luciferase expression plasmid, it is fully spliced but strongly stabilises the resulting luciferase transcript. In addition, by quantitative PCR we found that the retained and spliced forms are differentially expressed in tissues indicating an active regulation of the non-coding transcript. EST database analysis revealed that these genes have an alternative expression pathway with the formation of Transcription Induced Chimeras (TIC. This data was confirmed by RT-PCR, revealing the presence of different transcripts that would encode the chimeric proteins CSNKβ-LY6G5B and G6F-LY6G6D, in which the LY-6 domain would join to a kinase domain and an Ig-like domain, respectively. Conclusion In conclusion, the LY6G5B and LY6G6D intron-retained transcripts are not subjected to NMD and are more abundant than the properly spliced forms. In addition, these genes form chimeric transcripts with their neighbouring same orientation 5' genes. Of interest is the fact that the 5' genes (CSNKβ or G6F undergo differential splicing only in the context of the chimera (CSNKβ-LY6G5B or G6F-LY6G6C and not on their own.

Generation of anti-idiotype scFv for pharmacokinetic measurement in lymphoma patients treated with chimera anti-CD22 antibody SM03.

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Qi Zhao

Full Text Available Pre-clinical and clinical studies of therapeutic antibodies require highly specific reagents to examine their immune responses, bio-distributions, immunogenicity, and pharmacodynamics in patients. Selective antigen-mimicking anti-idiotype antibody facilitates the assessment of therapeutic antibody in the detection, quantitation and characterization of antibody immune responses. Using mouse specific degenerate primer pairs and splenocytic RNA, we generated an idiotype antibody-immunized phage-displayed scFv library in which an anti-idiotype antibody against the therapeutic chimera anti-CD22 antibody SM03 was isolated. The anti-idiotype scFv recognized the idiotype of anti-CD22 antibody and inhibited binding of SM03 to CD22 on Raji cell surface. The anti-idiotype scFv was subsequently classified as Ab2γ type. Moreover, our results also demonstrated firstly that the anti-idiotype scFv could be used for pharmacokinetic measurement of circulating residual antibody in lymphoma patients treated with chimera anti-CD22 monoclonal antibody SM03. Of important, the present approach could be easily adopted to generate anti-idiotype antibodies for therapeutic antibodies targeting membrane proteins, saving the cost and time for producing a soluble antigen.

Fascaplysin sensitizes cells to TRAIL-induced apoptosis through upregulating DR5 expression

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Wang, Feng; Chen, Haimin; Yan, Xiaojun; Zheng, Yanling

2013-05-01

This study investigated the molecular mechanism of anti-tumor effect of fascaplysin, a nitrogenous red pigment firstly isolated from a marine sponge. Microarray analysis show that the TNF and TNF receptor superfamily in human umbilical vein endothelial cells (HUVEC) and human hepatocarcinoma cells (BEL-7402) were significantly regulated by fascaplysin. Western Blot results reveal that fascaplysin increased the expression of cleaved caspase-9, active caspase-3, and decreased the level of procaspase-8 and Bid. Flow cytometry and cytotoxicity tests indicate that fascaplysin sensitized cells to tumor necrosis-related apoptosisinducing ligand-(TRAIL) induced apoptosis, which was markedly blocked by TRAIL R2/Fc chimera, a dominant negative form of TRAIL receptor DR5. Therefore, our results demonstrate that fascaplysin promotes apoptosis through the activation of TRAIL signaling pathway by upregulating DR5 expression.

Artificial muscle: the human chimera is the future.

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Tozzi, P

2011-12-14

Severe heart failure and cerebral stroke are broadly associated with the impairment of muscular function that conventional treatments struggle to restore. New technologies enable the construction of "smart" materials that could be of great help in treating diseases where the main problem is muscle weakness. These materials "behave" similarly to biological systems, because the material directly converts energy, for example electrical energy into movement. The extension and contraction occur silently like in natural muscles. The real challenge is to transfer this amazing technology into devices that restore or replace the mechanical function of failing muscle. Cardiac assist devices based on artificial muscle technology could envelope a weak heart and temporarily improve its systolic function, or, if placed on top of the atrium, restore the atrial kick in chronic atrial fibrillation. Artificial sphincters could be used to treat urinary incontinence after prostatectomy or faecal incontinence associated with stomas. Artificial muscles can restore the ability of patients with facial paralysis due to stroke or nerve injury to blink. Smart materials could be used to construct an artificial oesophagus including peristaltic movement and lower oesophageal sphincter function to replace the diseased oesophagus thereby avoiding the need for laparotomy to mobilise stomach or intestine. In conclusion, in the near future, smart devices will integrate with the human body to fill functional gaps due to organ failure, and so create a human chimera.

Surface functionalization of inorganic nano-crystals with fibronectin and E-cadherin chimera synergistically accelerates trans-gene delivery into embryonic stem cells

International Nuclear Information System (INIS)

Kutsuzawa, K.; Chowdhury, E.H.; Nagaoka, M.; Maruyama, K.; Akiyama, Y.; Akaike, T.

2006-01-01

Stem cells holding great promises in regenerative medicine have the potential to be differentiated to a specific cell type through genetic manipulation. However, conventional ways of gene transfer to such progenitor cells suffer from a number of disadvantages particularly involving safety and efficacy issues. Here, we report on the development of a bio-functionalized inorganic nano-carrier of DNA by embedding fibronectin and E-cadherin chimera on the carrier, leading to its high affinity interactions with embryonic stem cell surface and accelerated trans-gene delivery for subsequent expression. While only apatite nano-particles were very inefficient in transfecting embryonic stem cells, fibronectin-anchored particles and to a more significant extent, fibronectin and E-cadherin-Fc-associated particles dramatically enhanced trans-gene delivery with a value notably higher than that of commercially available lipofection system. The involvement of both cell surface integrin and E-cadherin in mediating intracellular localization of the hybrid carrier was verified by blocking integrin binding site with excess free fibronectin and up-regulating both integrin and E-cadherin through PKC activation. Thus, the new establishment of a bio-functional hybrid gene-carrier would promote and facilitate development of stem cell-based therapy in regenerative medicine

Development of a large scale Chimera grid system for the Space Shuttle Launch Vehicle

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Pearce, Daniel G.; Stanley, Scott A.; Martin, Fred W., Jr.; Gomez, Ray J.; Le Beau, Gerald J.; Buning, Pieter G.; Chan, William M.; Chiu, Ing-Tsau; Wulf, Armin; Akdag, Vedat

1993-01-01

The application of CFD techniques to large problems has dictated the need for large team efforts. This paper offers an opportunity to examine the motivations, goals, needs, problems, as well as the methods, tools, and constraints that defined NASA's development of a 111 grid/16 million point grid system model for the Space Shuttle Launch Vehicle. The Chimera approach used for domain decomposition encouraged separation of the complex geometry into several major components each of which was modeled by an autonomous team. ICEM-CFD, a CAD based grid generation package, simplified the geometry and grid topology definition by provoding mature CAD tools and patch independent meshing. The resulting grid system has, on average, a four inch resolution along the surface.

An expression tag toolbox for microbial production of membrane bound plant cytochromes P450

DEFF Research Database (Denmark)

Vazquez Albacete, Dario; Cavaleiro, Mafalda; Christensen, Ulla

2017-01-01

of the intermediate and the final product of the pathway. Finally, the effect of a robustly performing expression tag was explored with a library of 49 different P450s from medicinal plants and nearly half of these were improved in expression by more than 2-fold. The developed toolbox serves as platform to tune P450...... tag chimeras of the model plant P450 CYP79A1 in different Escherichia coli strains. Using a high-throughput screening platform based on C-terminal GFP fusions, we identify several highly expressing and robustly performing chimeric designs. Analysis of long-term cultures by flow cytometry showed...... homogeneous populations for some of the conditions. Three chimeric designs were chosen for a more complex combinatorial assembly of a multigene pathway consisting of two P450s and a redox partner. Cells expressing these recombinant enzymes catalysed the conversion of the substrate to highly different ratios...

The determination of lymphoid cell chimerism using peripheral blood lymphocytes from murine bone marrow chimeras

International Nuclear Information System (INIS)

Skidmore, B.J.; Miller, L.S.

1978-01-01

A simple, rapid and accurate method was devised for determining lymphoid cell chimerism in bone marrow-reconstituted mice. Chimeras were produced by reconstituting lethally irradiated mice with semi-allogeneic bone marrow cells. Lymphocytes from the peripheral blood of individual chimeric mice were purified by sedimentation in dextran solution and differential flotation in Ficoll-Hypaque gradients. From 250-500 μl of blood, 1-7 x 10 5 cells were routinely obtained. The extent of chimerism was determined serologically by using peripheral blood lymphocytes as target cells in a dye exclusion microcytotoxicity assay. Using this new technique, approximately 80% of the reconstituted mice were found to be repopulated with lymphocytes of the donor type. (Auth.)

Donor T cells primed on leukemia lysate-pulsed recipient APCs mediate strong graft-versus-leukemia effects across MHC barriers in full chimeras.

Science.gov (United States)

Ghosh, Arnab; Koestner, Wolfgang; Hapke, Martin; Schlaphoff, Verena; Länger, Florian; Baumann, Rolf; Koenecke, Christian; Cornberg, Markus; Welte, Karl; Blazar, Bruce R; Sauer, Martin G

2009-04-30

Antigen-presenting cells (APCs) of host origin drive graft-versus-leukemia (GVL) effects but can also trigger life-threatening graft-versus-host disease (GVHD) after hematopoietic cell transplantation (HCT) across major histocompatibility complex (MHC) barriers. We show that in vitro priming of donor lymphocytes can circumvent the need of recipient-derived APCs in vivo for mediating robust GVL effects and significantly diminishes the risk of severe GVHD. In vitro, generated and expanded T cells (ETCs) mediate anti-leukemia effects only when primed on recipient-derived APCs. Loading of APCs in vitro with leukemia cell lysate, chimerism status of the recipient, and timing of adoptive transfer after HCT are important factors determining the outcome. Delayed transfer of ETCs resulted in strong GVL effects in leukemia-bearing full chimera (FC) and mixed chimera (MC) recipients, which were comparable with the GVL/GVHD rates observed after the transfer of naive donor lymphocyte infusion (DLI). Upon early transfer, GVL effects were more pronounced with ETCs but at the expense of significant GVHD. The degree of GVHD was most severe in MCs after transfer of ETCs that had been in vitro primed either on nonpulsed recipient-derived APCs or with donor-derived APCs.

Focal glomerulosclerosis in proviral and c-fms transgenic mice links Vpr expression to HIV-associated nephropathy

International Nuclear Information System (INIS)

Dickie, Peter; Roberts, Amanda; Uwiera, Richard; Witmer, Jennifer; Sharma, Kirti; Kopp, Jeffrey B.

2004-01-01

Clinical and morphologic features of human immunodeficiency virus (HIV)-associated nephropathy (HIVAN), such as proteinuria, sclerosing glomerulopathy, tubular degeneration, and interstitial disease, have been modeled in mice bearing an HIV proviral transgene rendered noninfectious through a deletion in gag/pol. Exploring the genetic basis of HIVAN, HIV transgenic mice bearing mutations in either or both of the accessory genes nef and vpr were created. Proteinuria and focal glomerulosclerosis (FGS) only developed in mice with an intact vpr gene. Transgenic mice bearing a simplified proviral DNA (encoding only Tat and Vpr) developed renal disease characterized by FGS in which Vpr protein was localized to glomerular and tubular epithelia by immunohistochemistry. The dual transgenic progeny of HIV[Tat/Vpr] mice bred to HIV[ΔVpr] proviral transgenic mice displayed a more severe nephropathy with no apparent increase in Vpr expression, implying that multiple viral genes contribute to HIVAN. However, the unique contribution of macrophage-specific Vpr expression in the development of glomerular disease was underscored by the induction of FGS in multiple murine lines bearing a c-fms/vpr transgene

Particle identification method in the CsI(Tl) scintillator used for the CHIMERA 4 pi detector

CERN Document Server

Alderighi, M; Basssini, R; Berceanu, I; Blicharska, J; Boiano, C; Borderie, B; Bougault, R; Bruno, M; Cali, C; Cardella, G; Cavallaro, S; D'Agostino, M; D'andrea, M; Dayras, R; De Filippo, E; Fichera, F; Geraci, E; Giustolisi, F; Grzeszczuk, A; Guardone, N; Guazzoni, P; Guinet, D; Iacono-Manno, M; Kowalski, S; La Guidara, E; Lanchais, A L; Lanzalone, G; Lanzanò, G; Le Neindre, N; Li, S; Maiolino, C; Majka, Z; Manfredi, G; Nicotra, D; Paduszynski, T; Pagano, A; Papa, M; Petrovici, C M; Piasecki, E; Pirrone, S; Politi, G; Pop, A; Porto, F; Rivet, M F; Rosato, E; Sacca, G; Sechi, G; Simion, V; Sperduto, M L; Steckmeyer, J C; Trifiró, A; Trimarchi, M; Urso, S; Vannini, G; Vigilante, M; Wilczynski, J; Wu, H; Xiao, Z; Zetta, L; Zipper, W

2002-01-01

The charged particle identification obtained by the analysis of signals coming from the CsI(Tl) detectors of the CHIMERA 4 pi heavy-ion detector is presented. A simple double-gate integration method, with the use of the cyclotron radiofrequency as reference time, results in low thresholds for isotopic particle identification. The dependence of the identification quality on the gate generation timing is discussed. Isotopic identification of light ions up to Beryllium is clearly seen. For the first time also the identification of Z=5 particles is observed. The identification of neutrons interacting with CsI(Tl) by (n,alpha) and (n,gamma) reactions is also discussed.

Novel type of chimera spiral waves arising from decoupling of a diffusible component

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Tang, Xiaodong; Yang, Tao; Liu, Yang; Zhao, Yuemin; Gao, Qingyu, E-mail: epstein@brandeis.edu, E-mail: gaoqy@cumt.edu.cn [College of Chemical Engineering, China University of Mining and Technology, Xuzhou 221008 (China); Epstein, Irving R., E-mail: epstein@brandeis.edu, E-mail: gaoqy@cumt.edu.cn [Department of Chemistry and Volen Center for Complex Systems, MS 015, Brandeis University, Waltham, Massachusetts 02454-9110 (United States)

2014-07-14

Spiral waves composed of coherent traveling waves surrounding a core containing stochastically distributed stationary areas are found in numerical simulations of a three-variable reaction-diffusion system with one diffusible species. In the spiral core, diffusion of this component (w) mediates transitions between dynamic states of the subsystem formed by the other two components, whose dynamics is more rapid than that of w. Diffusive coupling between adjacent sites can be “on” or “off” depending on the subsystem state. The incoherent structures in the spiral core are produced by this decoupling of the slow diffusive component from the fast non-diffusing subsystem. The phase diagram reveals that the region of incoherent behavior in chimera spirals grows drastically, leading to modulation and breakup of the spirals, in the transition zones between 1{sup n-1} and 1{sup n} local mixed-mode oscillations.

Expression of a humanized SZ-63 McAb functional recombinant Fab fragment in E. Coli

International Nuclear Information System (INIS)

Xia Lijun; Gu Jianming; Zhang Xiaoming; Liu Yue; Wan Haiying; Li Peixia; Ruan Changgeng

1995-06-01

MRNA was selected on oligo(dT)-cellulose from total RNA isolated from SZ-63 hybridoma cells by CsCl ultracentrifugation. cDNA coding for heavy and light variable regions were amplified by reverse transcriptase-polymerase chain reaction (RT-PCR). The amplified fragments were then cloned and sequenced by the 32 P labelled sanger dideoxy-mediated chain-termination method. The nucleotides of VH and Vκ are 354 and 321 respectively, the amino acid sequence of heavy and light chain of SZ-63 were also deduced. Then, linking the variable genes of SZ-63 with human immunoglobulin γ 1 CH and κ VL genes, constructing pHEN1-63 Fab/Hu chimera for expression and transforming E. coli HB2151. The expressed chimeric SZ-63 Fab was soluble. Both ELISA and Western blot results showed the expression products could specifically bind with cross-linked fibrin and the content in expression culture was about 225 μg/L. (5 figs.)

Improved innate and adaptive immunostimulation by genetically modified HIV-1 protein expressing NYVAC vectors.

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Esther D Quakkelaar

Full Text Available Attenuated poxviruses are safe and capable of expressing foreign antigens. Poxviruses are applied in veterinary vaccination and explored as candidate vaccines for humans. However, poxviruses express multiple genes encoding proteins that interfere with components of the innate and adaptive immune response. This manuscript describes two strategies aimed to improve the immunogenicity of the highly attenuated, host-range restricted poxvirus NYVAC: deletion of the viral gene encoding type-I interferon-binding protein and development of attenuated replication-competent NYVAC. We evaluated these newly generated NYVAC mutants, encoding HIV-1 env, gag, pol and nef, for their ability to stimulate HIV-specific CD8 T-cell responses in vitro from blood mononuclear cells of HIV-infected subjects. The new vectors were evaluated and compared to the parental NYVAC vector in dendritic cells (DCs, RNA expression arrays, HIV gag expression and cross-presentation assays in vitro. Deletion of type-I interferon-binding protein enhanced expression of interferon and interferon-induced genes in DCs, and increased maturation of infected DCs. Restoration of replication competence induced activation of pathways involving antigen processing and presentation. Also, replication-competent NYVAC showed increased Gag expression in infected cells, permitting enhanced cross-presentation to HIV-specific CD8 T cells and proliferation of HIV-specific memory CD8 T-cells in vitro. The recombinant NYVAC combining both modifications induced interferon-induced genes and genes involved in antigen processing and presentation, as well as increased Gag expression. This combined replication-competent NYVAC is a promising candidate for the next generation of HIV vaccines.

Aerodynamic study of sounding rocket flows using Chimera and patched multiblock meshes

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João Alves de Oliveira Neto

2011-01-01

Full Text Available Aerodynamic flow simulations over a typical sounding rocket are presented in this paper. The work is inserted in the effort of developing computational tools necessary to simulate aerodynamic flows over configurations of interest for Instituto de Aeronáutica e Espaço of Departamento de Ciência e Tecnologia Aeroespacial. Sounding rocket configurations usually require fairly large fins and, quite frequently, have more than one set of fins. In order to be able to handle such configurations, the present paper presents a novel methodology which combines both Chimera and patched multiblock grids in the discretization of the computational domain. The flows of interest are modeled using the 3-D Euler equations and the work describes the details of discretization procedure, which uses a finite difference approach for structure, body-conforming, multiblock grids. The method is used to calculate the aerodynamics of a sounding rocket vehicle. The results indicate that the present approach can be a powerful aerodynamic analysis and design tool.

Increasing the biological activity of IL-2 and IL-15 through complexing with anti-IL-2 mAbs and Il-15Ralfa-Fc chimera

Czech Academy of Sciences Publication Activity Database

Votavová, Petra; Tomala, Jakub; Kovář, Marek

2014-01-01

Roč. 195, č. 1 (2014), s. 1-10 ISSN 0165-2478 R&D Projects: GA ČR GAP301/11/0325; GA MŠk(CZ) ED1.1.00/02.0109; GA ČR GA13-12885S Institutional support: RVO:61388971 Keywords : IL-2 * IL-15 * chimera Subject RIV: EC - Immunology Impact factor: 2.512, year: 2014

Assay for the detection of non-lethal changes that are expressed as a proliferative disadvantage in mouse (Mus musculus) embryo aggregation chimberas

International Nuclear Information System (INIS)

Obasaju, M.F.

1986-01-01

This study demonstrates the potential utility of the chimera embryo assay in measuring the effects of a variety of non-lethal, potentially hazardous environmental agents on normal mammalian embryonic cells. The two major findings to have emerged from this investigation are, (1) relative cellular contribution per embryo in chimeras was found to depend on the strain of the partner embryo and this relationship apparently does not require cell to cell contact between the partner embryos of the chimera and is already apparent after only two cell cycles; and (2) within the same outbred strain, exposure of one partner embryo in the chimera to either X-irradiation or chlorpromazine, at dose levels that were lower than those previously found to be embryotoxic; such toxicity was revealed as a proliferative disadvantage that was also evident after only 2 cell cycles. Partner embryos in the chimera were distinguished by labelling one of them with the fluorescent dye, fluorescein isothiocyanate (FITC), which was shown to have no detrimental effects on the proliferation rate of the labelled embryos

Solid-State Nuclear Magnetic Resonance Investigation of the Structural Topology and Lipid Interactions of a Viral Fusion Protein Chimera Containing the Fusion Peptide and Transmembrane Domain.

Science.gov (United States)

Yao, Hongwei; Lee, Myungwoon; Liao, Shu-Yu; Hong, Mei

2016-12-13

The fusion peptide (FP) and transmembrane domain (TMD) of viral fusion proteins play important roles during virus-cell membrane fusion, by inducing membrane curvature and transient dehydration. The structure of the water-soluble ectodomain of viral fusion proteins has been extensively studied crystallographically, but the structures of the FP and TMD bound to phospholipid membranes are not well understood. We recently investigated the conformations and lipid interactions of the separate FP and TMD peptides of parainfluenza virus 5 (PIV5) fusion protein F using solid-state nuclear magnetic resonance. These studies provide structural information about the two domains when they are spatially well separated in the fusion process. To investigate how these two domains are structured relative to each other in the postfusion state, when the ectodomain forms a six-helix bundle that is thought to force the FP and TMD together in the membrane, we have now expressed and purified a chimera of the FP and TMD, connected by a Gly-Lys linker, and measured the chemical shifts and interdomain contacts of the protein in several lipid membranes. The FP-TMD chimera exhibits α-helical chemical shifts in all the membranes examined and does not cause strong curvature of lamellar membranes or membranes with negative spontaneous curvature. These properties differ qualitatively from those of the separate peptides, indicating that the FP and TMD interact with each other in the lipid membrane. However, no 13 C- 13 C cross peaks are observed in two-dimensional correlation spectra, suggesting that the two helices are not tightly associated. These results suggest that the ectodomain six-helix bundle does not propagate into the membrane to the two hydrophobic termini. However, the loosely associated FP and TMD helices are found to generate significant negative Gaussian curvature to membranes that possess spontaneous positive curvature, consistent with the notion that the FP-TMD assembly may

SCHEMA computational design of virus capsid chimeras: calibrating how genome packaging, protection, and transduction correlate with calculated structural disruption.

Science.gov (United States)

Ho, Michelle L; Adler, Benjamin A; Torre, Michael L; Silberg, Jonathan J; Suh, Junghae

2013-12-20

Adeno-associated virus (AAV) recombination can result in chimeric capsid protein subunits whose ability to assemble into an oligomeric capsid, package a genome, and transduce cells depends on the inheritance of sequence from different AAV parents. To develop quantitative design principles for guiding site-directed recombination of AAV capsids, we have examined how capsid structural perturbations predicted by the SCHEMA algorithm correlate with experimental measurements of disruption in seventeen chimeric capsid proteins. In our small chimera population, created by recombining AAV serotypes 2 and 4, we found that protection of viral genomes and cellular transduction were inversely related to calculated disruption of the capsid structure. Interestingly, however, we did not observe a correlation between genome packaging and calculated structural disruption; a majority of the chimeric capsid proteins formed at least partially assembled capsids and more than half packaged genomes, including those with the highest SCHEMA disruption. These results suggest that the sequence space accessed by recombination of divergent AAV serotypes is rich in capsid chimeras that assemble into 60-mer capsids and package viral genomes. Overall, the SCHEMA algorithm may be useful for delineating quantitative design principles to guide the creation of libraries enriched in genome-protecting virus nanoparticles that can effectively transduce cells. Such improvements to the virus design process may help advance not only gene therapy applications but also other bionanotechnologies dependent upon the development of viruses with new sequences and functions.

Crystal structures of a GABAA-receptor chimera reveal new endogenous neurosteroid-binding sites.

Science.gov (United States)

Laverty, Duncan; Thomas, Philip; Field, Martin; Andersen, Ole J; Gold, Matthew G; Biggin, Philip C; Gielen, Marc; Smart, Trevor G

2017-11-01

γ-Aminobutyric acid receptors (GABA A Rs) are vital for controlling excitability in the brain. This is emphasized by the numerous neuropsychiatric disorders that result from receptor dysfunction. A critical component of most native GABA A Rs is the α subunit. Its transmembrane domain is the target for many modulators, including endogenous brain neurosteroids that impact anxiety, stress and depression, and for therapeutic drugs, such as general anesthetics. Understanding the basis for the modulation of GABA A R function requires high-resolution structures. Here we present the first atomic structures of a GABA A R chimera at 2.8-Å resolution, including those bound with potentiating and inhibitory neurosteroids. These structures define new allosteric binding sites for these modulators that are associated with the α-subunit transmembrane domain. Our findings will enable the exploitation of neurosteroids for therapeutic drug design to regulate GABA A Rs in neurological disorders.

Genetic resistance in experimental autoimmune encephalomyelitis. I. Analysis of the mechanism of LeR resistance using radiation chimeras

International Nuclear Information System (INIS)

Pelfrey, C.M.; Waxman, F.J.; Whitacre, C.C.

1989-01-01

Experimental autoimmune encephalomyelitis (EAE) is a cell-mediated autoimmune disease of the central nervous system that has been extensively studied in the rat. The Lewis rat is highly susceptible to the induction of EAE, while the Lewis resistant (LeR) rat is known to be resistant. In this paper, we demonstrate that the LeR rat, which was derived from the Lewis strain by inbreeding of fully resistant animals, is histocompatible with the Lewis strain. Radiation chimeras, a tool for distinguishing between immunologic and nonimmunologic resistance mechanisms, were utilized to analyze the cellular mechanisms involved in genetic resistance to EAE. By transplanting bone marrow cells from LeR rats into irradiated Lewis recipients, Lewis rats were rendered resistant to EAE induction. Likewise, transplanting Lewis bone marrow cells into irradiated LeR recipients rendered LeR rats susceptible. Mixed lymphoid cell chimeras using bone marrow, spleen, and thymus cells in Lewis recipient rats revealed individual lymphoid cell types and cell interactions that significantly affected the incidence and severity of EAE. Our results suggest that LeR resistance is mediated by hematopoietic/immune cells, and that cells located in the spleen appear to play a critical role in the resistance/susceptibility to EAE induction. Depletion of splenic adherent cells did not change the patterns of EAE resistance. In vivo cell mixing studies suggested the presence of a suppressor cell population in the LeR spleen preparations which exerted an inhibitory effect on Lewis autoimmune responses. Thus, the mechanism of LeR resistance appears to be different from that in other EAE-resistant animals

A chimera grid scheme. [multiple overset body-conforming mesh system for finite difference adaptation to complex aircraft configurations

Science.gov (United States)

Steger, J. L.; Dougherty, F. C.; Benek, J. A.

1983-01-01

A mesh system composed of multiple overset body-conforming grids is described for adapting finite-difference procedures to complex aircraft configurations. In this so-called 'chimera mesh,' a major grid is generated about a main component of the configuration and overset minor grids are used to resolve all other features. Methods for connecting overset multiple grids and modifications of flow-simulation algorithms are discussed. Computational tests in two dimensions indicate that the use of multiple overset grids can simplify the task of grid generation without an adverse effect on flow-field algorithms and computer code complexity.

NHE1 inhibition by amiloride- and benzoylguanidine-type compounds. Inhibitor binding loci deduced from chimeras of NHE1 homologues with endogenous differences in inhibitor sensitivity

DEFF Research Database (Denmark)

Pedersen, Stine F; King, Scott A; Nygaard, Eva B

2007-01-01

NHE1). Although highly homologous to the amiloride- and HOE-sensitive human NHE1 (hNHE1), AtNHE1 is insensitive to HOE-type and PaNHE1 to both amiloride- and HOE-type compounds. Here we generated chimeras to "knock in" amiloride and HOE sensitivity to PaNHE1, and we thereby identified several NHE1...

H-2 restriction specificity of T cells from H-2 incompatible radiation bone marrow chimeras: further evidence for the absence of crucial influence of the host/thymus environment on the generation of H-2 restricted TNP-specific T lymphocyte precursors

International Nuclear Information System (INIS)

Aizawa, S.; Sado, T.; Kubo, E.

1984-01-01

Experiments were conducted to answer the questions related to (a) the role played by the antigen-presenting cells (APCs) present within the thymus and (b) the effect of radiation dose to the recipients on the H-2 restriction profile of TNP-specific cytotoxic T lymphocyte precursors (CTLP) recovered from spleens and/or thymuses of H-2 incompatible radiation bone marrow chimeras (BMC). The H-2 restriction profile of intrathymically differentiating TNP-specific CTLPs was also analyzed in order to test an argument that donor-H-2 restricted CTLP detected in spleens of H-2 incompatible BMC were due to the extrathymically differentiated T cells under the influence of donor-derived lymphoreticular cells. The results indicated the following: (i) splenic T cells from B10(H-2b) leads to (B10(H-2b) leads to B10.BR(H-2k)) chimeras, which were constructed by irradiating primary B10 leads to B10.BR chimeras with 1100 R and reconstituting them with donor-type (B10) bone marrow cells as long as 8 months after their construction, manifested restriction specificities for both donor- and host-type H-2, (ii) splenic T cells from two types of (B10 X B10.BR)F1 leads to B10 chimeras which were reconstituted after exposure of the recipients with either 900 or 1100 R with donor-type bone marrow cells generated both donor- and host-H-2 restricted TNP-specific cytotoxic T cells, and (iii) the TNP-specific CTLPs present in the regenerating thymuses of B10.BR leads to B10 and (B10 X B10.BR)F1 leads to B10 chimeras 4 weeks after their construction were also shown to manifest both donor- and host-H-2 restriction specificities. The significance of these findings on the H-2 restriction profile of CTLP generated in BMCs is discussed

Novel BET protein proteolysis-targeting chimera exerts superior lethal activity than bromodomain inhibitor (BETi) against post-myeloproliferative neoplasm secondary (s) AML cells.

Science.gov (United States)

Saenz, D T; Fiskus, W; Qian, Y; Manshouri, T; Rajapakshe, K; Raina, K; Coleman, K G; Crew, A P; Shen, A; Mill, C P; Sun, B; Qiu, P; Kadia, T M; Pemmaraju, N; DiNardo, C; Kim, M-S; Nowak, A J; Coarfa, C; Crews, C M; Verstovsek, S; Bhalla, K N

2017-09-01

The PROTAC (proteolysis-targeting chimera) ARV-825 recruits bromodomain and extraterminal (BET) proteins to the E3 ubiquitin ligase cereblon, leading to degradation of BET proteins, including BRD4. Although the BET-protein inhibitor (BETi) OTX015 caused accumulation of BRD4, treatment with equimolar concentrations of ARV-825 caused sustained and profound depletion (>90%) of BRD4 and induced significantly more apoptosis in cultured and patient-derived (PD) CD34+ post-MPN sAML cells, while relatively sparing the CD34+ normal hematopoietic progenitor cells. RNA-Seq, Reverse Phase Protein Array and mass cytometry 'CyTOF' analyses demonstrated that ARV-825 caused greater perturbations in messenger RNA (mRNA) and protein expressions than OTX015 in sAML cells. Specifically, compared with OTX015, ARV-825 treatment caused more robust and sustained depletion of c-Myc, CDK4/6, JAK2, p-STAT3/5, PIM1 and Bcl-xL, while increasing the levels of p21 and p27. Compared with OTX015, PROTAC ARV-771 treatment caused greater reduction in leukemia burden and further improved survival of NSG mice engrafted with luciferase-expressing HEL92.1.7 cells. Co-treatment with ARV-825 and JAK inhibitor ruxolitinib was synergistically lethal against established and PD CD34+ sAML cells. Notably, ARV-825 induced high levels of apoptosis in the in vitro generated ruxolitinib-persister or ruxolitinib-resistant sAML cells. These findings strongly support the in vivo testing of the BRD4-PROTAC based combinations against post-MPN sAML.

A Navier-Strokes Chimera Code on the Connection Machine CM-5: Design and Performance

Science.gov (United States)

Jespersen, Dennis C.; Levit, Creon; Kwak, Dochan (Technical Monitor)

1994-01-01

We have implemented a three-dimensional compressible Navier-Stokes code on the Connection Machine CM-5. The code is set up for implicit time-stepping on single or multiple structured grids. For multiple grids and geometrically complex problems, we follow the 'chimera' approach, where flow data on one zone is interpolated onto another in the region of overlap. We will describe our design philosophy and give some timing results for the current code. A parallel machine like the CM-5 is well-suited for finite-difference methods on structured grids. The regular pattern of connections of a structured mesh maps well onto the architecture of the machine. So the first design choice, finite differences on a structured mesh, is natural. We use centered differences in space, with added artificial dissipation terms. When numerically solving the Navier-Stokes equations, there are liable to be some mesh cells near a solid body that are small in at least one direction. This mesh cell geometry can impose a very severe CFL (Courant-Friedrichs-Lewy) condition on the time step for explicit time-stepping methods. Thus, though explicit time-stepping is well-suited to the architecture of the machine, we have adopted implicit time-stepping. We have further taken the approximate factorization approach. This creates the need to solve large banded linear systems and creates the first possible barrier to an efficient algorithm. To overcome this first possible barrier we have considered two options. The first is just to solve the banded linear systems with data spread over the whole machine, using whatever fast method is available. This option is adequate for solving scalar tridiagonal systems, but for scalar pentadiagonal or block tridiagonal systems it is somewhat slower than desired. The second option is to 'transpose' the flow and geometry variables as part of the time-stepping process: Start with x-lines of data in-processor. Form explicit terms in x, then transpose so y-lines of data are

Chimeras in leaky integrate-and-fire neural networks: effects of reflecting connectivities

Science.gov (United States)

Tsigkri-DeSmedt, Nefeli Dimitra; Hizanidis, Johanne; Schöll, Eckehard; Hövel, Philipp; Provata, Astero

2017-07-01

The effects of attracting-nonlocal and reflecting connectivity are investigated in coupled Leaky Integrate-and-Fire (LIF) elements, which model the exchange of electrical signals between neurons. Earlier investigations have demonstrated that repulsive-nonlocal and hierarchical network connectivity can induce complex synchronization patterns and chimera states in systems of coupled oscillators. In the LIF system we show that if the elements are nonlocally linked with positive diffusive coupling on a ring network, the system splits into a number of alternating domains. Half of these domains contain elements whose potential stays near the threshold and they are interrupted by active domains where the elements perform regular LIF oscillations. The active domains travel along the ring with constant velocity, depending on the system parameters. When we introduce reflecting coupling in LIF networks unexpected complex spatio-temporal structures arise. For relatively extensive ranges of parameter values, the system splits into two coexisting domains: one where all elements stay near the threshold and one where incoherent states develop, characterized by multi-leveled mean phase velocity profiles.

HIV-1 induces DCIR expression in CD4+ T cells.

Directory of Open Access Journals (Sweden)

Alexandra A Lambert

2010-11-01

Full Text Available The C-type lectin receptor DCIR, which has been shown very recently to act as an attachment factor for HIV-1 in dendritic cells, is expressed predominantly on antigen-presenting cells. However, this concept was recently challenged by the discovery that DCIR can also be detected in CD4(+ T cells found in the synovial tissue from rheumatoid arthritis (RA patients. Given that RA and HIV-1 infections share common features such as a chronic inflammatory condition and polyclonal immune hyperactivation status, we hypothesized that HIV-1 could promote DCIR expression in CD4(+ T cells. We report here that HIV-1 drives DCIR expression in human primary CD4(+ T cells isolated from patients (from both aviremic/treated and viremic/treatment naive persons and cells acutely infected in vitro (seen in both virus-infected and uninfected cells. Soluble factors produced by virus-infected cells are responsible for the noticed DCIR up-regulation on uninfected cells. Infection studies with Vpr- or Nef-deleted viruses revealed that these two viral genes are not contributing to the mechanism of DCIR induction that is seen following acute infection of CD4(+ T cells with HIV-1. Moreover, we report that DCIR is linked to caspase-dependent (induced by a mitochondria-mediated generation of free radicals and -independent intrinsic apoptotic pathways (involving the death effector AIF. Finally, we demonstrate that the higher surface expression of DCIR in CD4(+ T cells is accompanied by an enhancement of virus attachment/entry, replication and transfer. This study shows for the first time that HIV-1 induces DCIR membrane expression in CD4(+ T cells, a process that might promote virus dissemination throughout the infected organism.

Chimera and modulated drift states in a ring of nonlocally coupled oscillators with heterogeneous phase lags

Science.gov (United States)

Choe, Chol-Ung; Kim, Ryong-Son; Ri, Ji-Song

2017-09-01

We consider a ring of phase oscillators with nonlocal coupling strength and heterogeneous phase lags. We analyze the effects of heterogeneity in the phase lags on the existence and stability of a variety of steady states. A nonlocal coupling with heterogeneous phase lags that allows the system to be solved analytically is suggested and the stability of solutions along the Ott-Antonsen invariant manifold is explored. We present a complete bifurcation diagram for stationary patterns including the uniform drift and modulated drift states as well as chimera state, which reveals that the stable modulated drift state and a continuum of metastable drift states could occur due to the heterogeneity of the phase lags. We verify our theoretical results using the direct numerical simulations of the model system.

Transient Expression and Cellular Localization of Recombinant Proteins in Cultured Insect Cells.

Science.gov (United States)

Fabrick, Jeffrey A; Hull, J Joe

2017-04-20

Heterologous protein expression systems are used for the production of recombinant proteins, the interpretation of cellular trafficking/localization, and the determination of the biochemical function of proteins at the sub-organismal level. Although baculovirus expression systems are increasingly used for protein production in numerous biotechnological, pharmaceutical, and industrial applications, nonlytic systems that do not involve viral infection have clear benefits but are often overlooked and underutilized. Here, we describe a method for generating nonlytic expression vectors and transient recombinant protein expression. This protocol allows for the efficient cellular localization of recombinant proteins and can be used to rapidly discern protein trafficking within the cell. We show the expression of four recombinant proteins in a commercially available insect cell line, including two aquaporin proteins from the insect Bemisia tabaci, as well as subcellular marker proteins specific for the cell plasma membrane and for intracellular lysosomes. All recombinant proteins were produced as chimeras with fluorescent protein markers at their carboxyl termini, which allows for the direct detection of the recombinant proteins. The double transfection of cells with plasmids harboring constructs for the genes of interest and a known subcellular marker allows for live cell imaging and improved validation of cellular protein localization.

Diverse cellular architecture of atherosclerotic plaque derives from clonal expansion of a few medial SMCs

DEFF Research Database (Denmark)

Jacobsen, Kevin; Lund, Marie Bek; Shim, Jeong

2017-01-01

chimeras of eGFP+Apoe-/- and Apoe-/- mouse embryos and in mice with a mosaic expression of fluorescent proteins in medial SMCs that were rendered atherosclerotic by PCSK9-induced hypercholesterolemia. Fibrous caps in aggregation chimeras were found constructed from large, endothelial-aligned layers...... in the cap and heterogeneous ACTA2- SMCs in the plaque interior, including chondrocyte-like cells and cells with intracellular lipid and crystalline material. Fibrous cap SMCs were invariably arranged in endothelium-aligned clonal sheets, confirming results in the aggregation chimeras. Analysis of the clonal...

2D and 3D core-collapse supernovae simulation results obtained with the CHIMERA code

Energy Technology Data Exchange (ETDEWEB)

Bruenn, S W; Marronetti, P; Dirk, C J [Physics Department, Florida Atlantic University, 777 W. Glades Road, Boca Raton, FL 33431-0991 (United States); Mezzacappa, A; Hix, W R [Physics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6354 (United States); Blondin, J M [Department of Physics, North Carolina State University, Raleigh, NC 27695-8202 (United States); Messer, O E B [Center for Computational Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6354 (United States); Yoshida, S, E-mail: bruenn@fau.ed [Max-Planck-Institut fur Gravitationsphysik, Albert Einstein Institut, Golm (Germany)

2009-07-01

Much progress in realistic modeling of core-collapse supernovae has occurred recently through the availability of multi-teraflop machines and the increasing sophistication of supernova codes. These improvements are enabling simulations with enough realism that the explosion mechanism, long a mystery, may soon be delineated. We briefly describe the CHIMERA code, a supernova code we have developed to simulate core-collapse supernovae in 1, 2, and 3 spatial dimensions. We then describe the results of an ongoing suite of 2D simulations initiated from a 12, 15, 20, and 25 M{sub o-dot} progenitor. These have all exhibited explosions and are currently in the expanding phase with the shock at between 5,000 and 20,000 km. We also briefly describe an ongoing simulation in 3 spatial dimensions initiated from the 15 M{sub o-dot} progenitor.

Expression and Purification of the Main Component Contained in Camel Milk and Its Antimicrobial Activities Against Bacterial Plant Pathogens.

Science.gov (United States)

Tanhaeian, Abbas; Shahriari Ahmadi, Farajollah; Sekhavati, Mohammad Hadi; Mamarabadi, Mojtaba

2018-04-04

Lactoferrin is the most dominant protein in milk after casein. This protein plays a crucial role in many biological processes including the regulation of iron metabolism, induction and modulation of the immune system, the primary defense against microorganisms, inhibiting lipid peroxidation and presenting antimicrobial activity against various pathogens such as parasites, fungi, bacteria, and viruses. The major antimicrobial effect of lactoferrin is related to its N-terminal tail where different peptides for instance lactoferricin and lactoferrampin which are important for their antimicrobial abilities are present. The growth rate of bacterial cells in camel milk is lower than that of the cow milk due to having more antimicrobial compounds. In this study, we have fused a codon-optimized partial camel lactoferrcin and lactoferrampin DNA sequences in order to construct a fused peptide via a lysine. This chimeric 42-mer peptide consists of complete and partial amino acid sequence of camel lactoferrampin and lactoferricin, respectively. Human embryonic kidney 293 (HEK-293) cells were used for synthesizing this recombinant peptide. Finally, the antibacterial activities of this constructed peptide were investigated under in vitro condition. The result showed that, all construction, cloning and expression processes were successfully performed in HEK-293. One His-tag tail was added to the chimera in order to optimize the isolation and purification processes and also reduce the cost of production. Additionally, His-tag retained the antimicrobial activity of the chimera. The antimicrobial tests showed that the growth rate in the majority of bacterial plant pathogens, including gram negative and positive bacteria, was inhibited by recombinant chimera as the level of MIC values were evaluated between 0.39 and 25.07 μg/ml for different bacterial isolates.

Lack of adaptation to human tetherin in HIV-1 Group O and P

Science.gov (United States)

2011-01-01

Background HIV-1 viruses are categorized into four distinct groups: M, N, O and P. Despite the same genomic organization, only the group M viruses are responsible for the world-wide pandemic of AIDS, suggesting better adaptation to human hosts. Previously, it has been reported that the group M Vpu protein is capable of both down-modulating CD4 and counteracting BST-2/tetherin restriction, while the group O Vpu cannot antagonize tetherin. This led us to investigate if group O, and the related group P viruses, possess functional anti-tetherin activities in Vpu or another viral protein, and to further map the residues required for group M Vpu to counteract human tetherin. Results We found a lack of activity against human tetherin for both the Vpu and Nef proteins from group O and P viruses. Furthermore, we found no evidence of anti-human tetherin activity in a fully infectious group O proviral clone, ruling out the possibility of an alternative anti-tetherin factor in this virus. Interestingly, an activity against primate tetherins was retained in the Nef proteins from both a group O and a group P virus. By making chimeras between a functional group M and non-functional group O Vpu protein, we were able to map the first 18 amino acids of group M Vpu as playing an essential role in the ability of the protein to antagonize human tetherin. We further demonstrated the importance of residue alanine-18 for the group M Vpu activity. This residue lies on a diagonal face of conserved alanines in the TM domain of the protein, and is necessary for specific Vpu-tetherin interactions. Conclusions The absence of human specific anti-tetherin activities in HIV-1 group O and P suggests a failure of these viruses to adapt to human hosts, which may have limited their spread. PMID:21955466

Lack of adaptation to human tetherin in HIV-1 Group O and P

Directory of Open Access Journals (Sweden)

Haworth Kevin G

2011-09-01

Full Text Available Abstract Background HIV-1 viruses are categorized into four distinct groups: M, N, O and P. Despite the same genomic organization, only the group M viruses are responsible for the world-wide pandemic of AIDS, suggesting better adaptation to human hosts. Previously, it has been reported that the group M Vpu protein is capable of both down-modulating CD4 and counteracting BST-2/tetherin restriction, while the group O Vpu cannot antagonize tetherin. This led us to investigate if group O, and the related group P viruses, possess functional anti-tetherin activities in Vpu or another viral protein, and to further map the residues required for group M Vpu to counteract human tetherin. Results We found a lack of activity against human tetherin for both the Vpu and Nef proteins from group O and P viruses. Furthermore, we found no evidence of anti-human tetherin activity in a fully infectious group O proviral clone, ruling out the possibility of an alternative anti-tetherin factor in this virus. Interestingly, an activity against primate tetherins was retained in the Nef proteins from both a group O and a group P virus. By making chimeras between a functional group M and non-functional group O Vpu protein, we were able to map the first 18 amino acids of group M Vpu as playing an essential role in the ability of the protein to antagonize human tetherin. We further demonstrated the importance of residue alanine-18 for the group M Vpu activity. This residue lies on a diagonal face of conserved alanines in the TM domain of the protein, and is necessary for specific Vpu-tetherin interactions. Conclusions The absence of human specific anti-tetherin activities in HIV-1 group O and P suggests a failure of these viruses to adapt to human hosts, which may have limited their spread.

High Resolution Land Surface Modeling over the NEF Basin in the Chilean Patagonia

Science.gov (United States)

Somos-Valenzuela, M. A.

2017-12-01

be transfer to a regional setting and pseudo climate data will be used to study the impacts of climate change in the Baker River Basin system hydrology. The expected results are: 1) Land cover change maps and trends, and their relationship to changes in streamflow, and climate observations. 2) a calibrated hydro glaciology model for a catchment in the NEF river Basin

New insights into structure-function relationship of the DHPR beta1a subunit in skeletal muscle excitation-contraction coupling using zebrafish 'relaxed' as an expression system

International Nuclear Information System (INIS)

Dayal, A.

2010-01-01

mechanism or already contributes at the ultrastructural level i.e. DHPR tetrad arrangement. Surprisingly, our experiments revealed full tetrad formation and an almost complete restoration of EC coupling in [beta]1-null zebrafish relaxed larvae and isolated myotubes upon expression of a [beta]1a-specific heptad repeat mutant (LVV to AAA) and thus contradict the earlier results. According to our novel finding that the [beta]1a heptad repeat motif is not the key determinant of DHPR-RyR1 coupling, the next aim was to perform further in-depth structural-functional studies on the role of the DHPR [beta]1a subunit in skeletal muscle EC coupling. Previous loss-of-function studies identified the [beta]1a C-terminus as a key determinant of skeletal muscle EC coupling. However, loss-of-function studies always raise concerns if the observed effects are solely due to a more general loss of function because of global protein misfolding. Consequently, we were rather interested to carry out a gain-of-function approach. The ancestral [beta] subunit, [beta]M, despite lacking major parts of the variable N-, C-termini and the HOOK region is able to perform all basic [beta]-functions as mentioned above. So, we used [beta]M as the basis for chimeric gain-of-function experiments to probe for in vivo rescue of EC coupling via the larval motility restoration. Systematic expression studies with [beta]M/[beta]1a chimeras carrying substitutions of all variable (C-, N-termini, and HOOK) and conserved regions (SH3 and GK domains) were performed. All the heterologously expressed [beta]M/[beta]1a chimeras completely restored [alpha]1S triad targeting in relaxed myotubes. Surprisingly, [beta]M/[beta]1a chimeras carrying substitutions of either N- or C-terminus, or of all the three variable regions together with [beta]1a sequence displayed very reduced larval motility restoration. Thus, in clear contrast to the expectations raised by previous loss-of-function studies with [beta]2a/[beta]1a chimeras by

Fragmentation studies with the CHIMERA detector at LNS in Catania: recent progress

Energy Technology Data Exchange (ETDEWEB)

Pagano, A.; Alderighi, M.; Amorini, F.; Anzalone, A.; Arena, L.; Auditore, L.; Baran, V.; Bartolucci, M.; Berceanu, I.; Blicharska, J.; Brzychczyk, J.; Bonasera, A.; Borderie, B.; Bougault, R.; Bruno, M.; Cardella, G.; Cavallaro, S.; Chatterjee, M.B.; Chbihi, A.; Cibor, J.; Colonna, M.; D' Agostino, M.; Dayras, R.; De Filippo, E.; Di Toro, M.; Gawlikowicz, W.; Geraci, E.; Giustolisi, F.; Grzeszczuk, A.; Guazzoni, P.; Guinet, D.; Iacono-Manno, M.; Kowalski, S.; La Guidara, E.; Lanzano, G.; Lanzalone, G.; Le Neindre, N.; Li, S.; Lo Nigro, S.; Maiolino, C.; Majka, Z.; Manfredi, G.; Paduszynski, T.; Papa, M.; Petrovici, M.; Piasecki, E.; Pirrone, S.; Planeta, R.; Politi, G.; Pop, A.; Porto, F.; Rivet, M.F.; Rosato, E.; Rizzo, F.; Russo, S.; Russotto, P.; Sassi, M.; Sechi, G.; Simion, V.; Siwek-Wilczynska, K.; Skwira, I.; Sperduto, M.L.; Steckmeyer, J.C.; Swiderski, L.; Trifiro, A.; Trimarchi, M.; Vannini, G.; Vigilante, M.; Wieleczko, J.P.; Wilczynski, J.; Wu, H.; Xiao, Z.; Zetta, L.; Zipper, W

2004-04-05

The new detector CHIMERA, in its final 4{pi} configuration, has been installed at Laboratori Nazionali del Sud (LNS) in Catania in January 2003. Beams of different energies ranging from protons to Au ions were delivered by the Tandem and the Super Conducting Cyclotron for nuclear reaction studies, in agreement with the approval of the Scientific Advisory Committee of LNS. Recent experimental results confirm very low energy thresholds of the trigger (below 0.5 MeV/nucleon), ensured within a wide dynamical range. Good characteristics of identification of light charged particles and heavy fragments have been obtained by using three detection techniques: {delta}E-E, {delta}E-time of flight, and the Pulse-Shape discrimination method. We present results of recent analysis concerning the production of intermediate mass fragments (IMF) in semi-peripheral collisions. Our results combined with theoretical Boltzmann-Nordheim-Vlasov simulations clearly demonstrate the presence of very fast processes of IMF production in the overlapping region of the target and projectile nuclei during re-separation, i.e. in the time scale comparable with the collision time. Evidence for slower, sequential-like production of IMF's is also shown.

Fragmentation studies with the CHIMERA detector at LNS in Catania: recent progress

International Nuclear Information System (INIS)

Pagano, A.; Alderighi, M.; Amorini, F.; Anzalone, A.; Arena, L.; Auditore, L.; Baran, V.; Bartolucci, M.; Berceanu, I.; Blicharska, J.; Brzychczyk, J.; Bonasera, A.; Borderie, B.; Bougault, R.; Bruno, M.; Cardella, G.; Cavallaro, S.; Chatterjee, M.B.; Chbihi, A.; Cibor, J.; Colonna, M.; D'Agostino, M.; Dayras, R.; De Filippo, E.; Di Toro, M.; Gawlikowicz, W.; Geraci, E.; Giustolisi, F.; Grzeszczuk, A.; Guazzoni, P.; Guinet, D.; Iacono-Manno, M.; Kowalski, S.; La Guidara, E.; Lanzano, G.; Lanzalone, G.; Le Neindre, N.; Li, S.; Lo Nigro, S.; Maiolino, C.; Majka, Z.; Manfredi, G.; Paduszynski, T.; Papa, M.; Petrovici, M.; Piasecki, E.; Pirrone, S.; Planeta, R.; Politi, G.; Pop, A.; Porto, F.; Rivet, M.F.; Rosato, E.; Rizzo, F.; Russo, S.; Russotto, P.; Sassi, M.; Sechi, G.; Simion, V.; Siwek-Wilczynska, K.; Skwira, I.; Sperduto, M.L.; Steckmeyer, J.C.; Swiderski, L.; Trifiro, A.; Trimarchi, M.; Vannini, G.; Vigilante, M.; Wieleczko, J.P.; Wilczynski, J.; Wu, H.; Xiao, Z.; Zetta, L.; Zipper, W.

2004-01-01

The new detector CHIMERA, in its final 4π configuration, has been installed at Laboratori Nazionali del Sud (LNS) in Catania in January 2003. Beams of different energies ranging from protons to Au ions were delivered by the Tandem and the Super Conducting Cyclotron for nuclear reaction studies, in agreement with the approval of the Scientific Advisory Committee of LNS. Recent experimental results confirm very low energy thresholds of the trigger (below 0.5 MeV/nucleon), ensured within a wide dynamical range. Good characteristics of identification of light charged particles and heavy fragments have been obtained by using three detection techniques: ΔE-E, ΔE-time of flight, and the Pulse-Shape discrimination method. We present results of recent analysis concerning the production of intermediate mass fragments (IMF) in semi-peripheral collisions. Our results combined with theoretical Boltzmann-Nordheim-Vlasov simulations clearly demonstrate the presence of very fast processes of IMF production in the overlapping region of the target and projectile nuclei during re-separation, i.e. in the time scale comparable with the collision time. Evidence for slower, sequential-like production of IMF's is also shown

[Molecular cloning, expression of rat Msx-1 and Msx-2 during early embryo genesis and roles for mandibular chondrogenesis].

Science.gov (United States)

Ishiguro, S

1999-03-01

Quail-chick chimera experiments have shown a contribution of carnial neural crest cells to the craniofacial skeletal elements. Moreover, tissue interactions between epithelial-mesenchymal interaction during early facial process development are required for both skeletal differentiation and morphogenesis. In this study, it was observed that Msx homeobox containing genes expressed in the facial process were important molecules of cartilage morphogenesis. Rat cDNAs were isolated and encoded by Msx-1 and -2, and then the expression patterns using in situ hybridization were investigated during early rat face development. These genes were correlatively expressed in the cranial neural crest forming area (E 9.5 dpc) and the facial process (E 12.5 dpc). Antisence inhibition of Msx genes in the E 12.5 mandibular process exhibited the alteration of their gene expression and cartilage patterns. Antisence inhibition of Msx-1 induced lack of the medial portion of cartilage, and antisence inhibition of Msx-2 enhanced chondrogenesis of mandibular process under the organ culture condition. Thus it was concluded that expression of Msx genes during mandibular process development comprises important signals of chondrogenesis.

Induction of cell scattering by expression of beta1 integrins in beta1-deficient epithelial cells requires activation of members of the rho family of GTPases and downregulation of cadherin and catenin function

DEFF Research Database (Denmark)

Gimond, C; van Der Flier, A; van Delft, S

1999-01-01

different beta1-null cell lines, epithelial GE11 and fibroblast-like GD25 cells. Expression of beta1A or the cytoplasmic splice variant beta1D, induced the disruption of intercellular adherens junctions and cell scattering in both GE11 and GD25 cells. In GE11 cells, the morphological change correlated...... for a complete morphological transition towards the spindle-shaped fibroblast-like phenotype. The expression of an interleukin-2 receptor (IL2R)-beta1A chimera and its incorporation into focal adhesions also induced the disruption of cadherin-based adhesions and the reorganization of ECM-cell contacts...

Primordial germ cell-mediated chimera technology produces viable pure-line Houbara bustard offspring: potential for repopulating an endangered species.

Directory of Open Access Journals (Sweden)

Ulrich Wernery

2010-12-01

Full Text Available The Houbara bustard (Chlamydotis undulata is a wild seasonal breeding bird populating arid sandy semi-desert habitats in North Africa and the Middle East. Its population has declined drastically during the last two decades and it is classified as vulnerable. Captive breeding programmes have, hitherto, been unsuccessful in reviving population numbers and thus radical technological solutions are essential for the long term survival of this species. The purpose of this study was to investigate the use of primordial germ cell-mediated chimera technology to produce viable Houbara bustard offspring.Embryonic gonadal tissue was dissected from Houbara bustard embryos at eight days post-incubation. Subsequently, Houbara tissue containing gonadal primordial germ cells (gPGCs was injected into White Leghorn chicken (Gallus gallus domesticus embryos, producing 83/138 surviving male chimeric embryos, of which 35 chimeric roosters reached sexual maturity after 5 months. The incorporation and differentiation of Houbara gPGCs in chimeric chicken testis were assessed by PCR with Houbara-specific primers and 31.3% (5/16 gonads collected from the injected chicken embryos showed the presence of donor Houbara cells. A total of 302 semen samples from 34 chimeric roosters were analyzed and eight were confirmed as germline chimeras. Semen samples from these eight roosters were used to artificially inseminate three female Houbara bustards. Subsequently, 45 Houbara eggs were obtained and incubated, two of which were fertile. One egg hatched as a male live born Houbara; the other was female but died before hatching. Genotyping confirmed that the male chick was a pure-line Houbara derived from a chimeric rooster.This study demonstrates for the first time that Houbara gPGCs can migrate, differentiate and eventually give rise to functional sperm in the chimeric chicken testis. This approach may provide a promising tool for propagation and conservation of endangered avian

Aptamer-miRNA-212 Conjugate Sensitizes NSCLC Cells to TRAIL

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Margherita Iaboni

2016-01-01

Full Text Available TNF-related apoptosis-inducing ligand (TRAIL is a promising antitumor agent for its remarkable ability to selectively induce apoptosis in cancer cells, without affecting the viability of healthy bystander cells. The TRAIL tumor suppressor pathway is deregulated in many human malignancies including lung cancer. In human non-small cell lung cancer (NSCLC cells, sensitization to TRAIL therapy can be restored by increasing the expression levels of the tumor suppressor microRNA-212 (miR-212 leading to inhibition of the anti-apoptotic protein PED/PEA-15 implicated in treatment resistance. In this study, we exploited a previously described RNA aptamer inhibitor of the tyrosine kinase receptor Axl (GL21.T expressed on lung cancer cells, as a means to deliver miR-212 into human NSCLC cells expressing Axl. We demonstrate efficient delivery of miR-212 following conjugation of the miR to GL21.T (GL21.T-miR212 chimera. We show that the chimera downregulates PED and restores TRAIL-mediate cytotoxicity in cancer cells. Importantly, treatment of Axl+ lung cancer cells with the chimera resulted in (i an increase in caspase activation and (ii a reduction of cell viability in combination with TRAIL therapy. In conclusion, we demonstrate that the GL21.T-miR212 chimera can be employed as an adjuvant to TRAIL therapy for the treatment of lung cancer.

Simulation of unsteady flows through stator and rotor blades of a gas turbine using the Chimera method

Science.gov (United States)

Nakamura, S.; Scott, J. N.

1993-01-01

A two-dimensional model to solve compressible Navier-Stokes equations for the flow through stator and rotor blades of a turbine is developed. The flow domains for the stator and rotor blades are coupled by the Chimera method that makes grid generation easy and enhances accuracy because the area of the grid that have high turning of grid lines or high skewness can be eliminated from the computational domain after the grids are generated. The results of flow computations show various important features of unsteady flows including the acoustic waves interacting with boundary layers, Karman vortex shedding from the trailing edge of the stator blades, pulsating incoming flow to a rotor blade from passing stator blades, and flow separation from both suction and pressure sides of the rotor blades.

Plant immunity triggered by engineered in vivo release of oligogalacturonides, damage-associated molecular patterns.

Science.gov (United States)

Benedetti, Manuel; Pontiggia, Daniela; Raggi, Sara; Cheng, Zhenyu; Scaloni, Flavio; Ferrari, Simone; Ausubel, Frederick M; Cervone, Felice; De Lorenzo, Giulia

2015-04-28

Oligogalacturonides (OGs) are fragments of pectin that activate plant innate immunity by functioning as damage-associated molecular patterns (DAMPs). We set out to test the hypothesis that OGs are generated in planta by partial inhibition of pathogen-encoded polygalacturonases (PGs). A gene encoding a fungal PG was fused with a gene encoding a plant polygalacturonase-inhibiting protein (PGIP) and expressed in transgenic Arabidopsis plants. We show that expression of the PGIP-PG chimera results in the in vivo production of OGs that can be detected by mass spectrometric analysis. Transgenic plants expressing the chimera under control of a pathogen-inducible promoter are more resistant to the phytopathogens Botrytis cinerea, Pectobacterium carotovorum, and Pseudomonas syringae. These data provide strong evidence for the hypothesis that OGs released in vivo act as a DAMP signal to trigger plant immunity and suggest that controlled release of these molecules upon infection may be a valuable tool to protect plants against infectious diseases. On the other hand, elevated levels of expression of the chimera cause the accumulation of salicylic acid, reduced growth, and eventually lead to plant death, consistent with the current notion that trade-off occurs between growth and defense.

Generation and characterization of a stable cell population releasing fluorescent HIV-1-based Virus Like Particles in an inducible way

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Bosch Valerie

2006-12-01

Full Text Available Abstract Background The availability of cell lines releasing fluorescent viral particles can significantly support a variety of investigations, including the study of virus-cell interaction and the screening of antiviral compounds. Regarding HIV-1, the recovery of such biologic reagents represents a very hard challenge due to the intrinsic cytotoxicity of many HIV-1 products. We sought to overcome such a limitation by using a cell line releasing HIV-1 particles in an inducible way, and by exploiting the ability of a HIV-1 Nef mutant to be incorporated in virions at quite high levels. Results Here, we report the isolation and characterization of a HIV-1 packaging cell line, termed 18-4s, able to release valuable amounts of fluorescent HIV-1 based Virus-Like Particles (VLPs in an inducible way. 18-4s cells were recovered by constitutively expressing the HIV-1 NefG3C mutant fused with the enhanced-green fluorescent protein (NefG3C-GFP in a previously isolated inducible HIV-1 packaging cell line. The G3C mutation creates a palmitoylation site which results in NefG3C-GFP incorporation into virions greatly exceeding that of the wild type counterpart. Upon induction of 18-4s cells with ponasterone A and sodium butyrate, up to 4 μg/ml of VLPs, which had incorporated about 150 molecules of NefG3C-GFP per viral particle, were released into the culture supernatant. Due to their intrinsic strong fluorescence, the 18-4s VLPs were easily detectable by a novel cytofluorometric-based assay developed here. The treatment of target cells with fluorescent 18-4 VLPs pseudotyped with different glycoprotein receptors resulted in these becoming fluorescent as early as two hours post-challenge. Conclusion We created a stable cell line releasing fluorescent HIV-1 based VLPs upon induction useful for several applications including the study of virus-cell interactions and the screening of antiviral compounds.

Ability of herpes simplex virus vectors to boost immune responses to DNA vectors and to protect against challenge by simian immunodeficiency virus

International Nuclear Information System (INIS)

Kaur, Amitinder; Sanford, Hannah B.; Garry, Deirdre; Lang, Sabine; Klumpp, Sherry A.; Watanabe, Daisuke; Bronson, Roderick T.; Lifson, Jeffrey D.; Rosati, Margherita; Pavlakis, George N.; Felber, Barbara K.; Knipe, David M.; Desrosiers, Ronald C.

2007-01-01

The immunogenicity and protective capacity of replication-defective herpes simplex virus (HSV) vector-based vaccines were examined in rhesus macaques. Three macaques were inoculated with recombinant HSV vectors expressing Gag, Env, and a Tat-Rev-Nef fusion protein of simian immunodeficiency virus (SIV). Three other macaques were primed with recombinant DNA vectors expressing Gag, Env, and a Pol-Tat-Nef-Vif fusion protein prior to boosting with the HSV vectors. Robust anti-Gag and anti-Env cellular responses were detected in all six macaques. Following intravenous challenge with wild-type, cloned SIV239, peak and 12-week plasma viremia levels were significantly lower in vaccinated compared to control macaques. Plasma SIV RNA in vaccinated macaques was inversely correlated with anti-Rev ELISPOT responses on the day of challenge (P value < 0.05), anti-Tat ELISPOT responses at 2 weeks post challenge (P value < 0.05) and peak neutralizing antibody titers pre-challenge (P value 0.06). These findings support continued study of recombinant herpesviruses as a vaccine approach for AIDS

Suppressed phenylalanine ammonia-lyase activity after heat shock in transgenic Nicotiana plumbaginifolia containing an Arabidopsis HSP18.2-parsley PAL2 chimera gene.

Science.gov (United States)

Moriwaki, M; Yamakawa, T; Washino, T; Kodama, T; Igarashi, Y

1999-01-01

The activity of phenylalanine ammonia-lyase (PAL; EC 4.3.1.5) after heat shock (HS) in leaves and buds of transgenic Nicotiana plumbaginifolia containing an Arabidopsis HSP18.2 promoter-parsley phenylalanine ammonia-lyase 2 (HSP18.2-PAL2) chimera gene was examined. Immediately after HS treatment at 44 degrees C for 5 h, the PAL activity in both transgenic and normal (untransformed) plants was 35-38% lower than that before HS. At normal temperature (25-26 degrees C), the PAL activity recovered within 5 h of ending the HS treatment in normal plants, but not until 12-24 h in transgenic plants containing the HSP18.2-PAL2 gene. Reverse transcription-polymerase chain reaction (RT-PCR) analysis revealed the presence of parsley PAL2 mRNA in transgenic plants, which remained for 8-12 h following 5-h HS at 44 degrees C; the mRNA was not observed before HS. The content of chlorogenic acid (CGA; 3-caffeoylquinic acid) decreased drastically 8-12 h after HS in transgenic plants, but only slightly in normal plants. Thus, the decrease in PAL activity accompanied by expression of the parsley PAL2 gene after HS treatment corresponded to the decrease in CGA synthesis. These results might be attributed to post-transcriptional degradation of endogenous PAL mRNA triggered by transcription of the transgene.

Why the moratorium on human-animal chimera research should not be lifted.

Science.gov (United States)

Moy, Alan

2017-08-01

The National Institutes of Health (NIH) announced its plans to lift its moratorium on funding research that involves injecting human embryonic stem cells into animal embryos, which would allow for the creation of part-human and part-animal organisms known as chimeras. The NIH allowed only one month to receive public comments in the midst of a presidential election campaign. Lifting the moratorium means that, for the first time, the federal government will begin spending taxpayer dollars on the creation and manipulation of new organisms that would blur the line between humans and animals. Interestingly, this government effort is creating an uncommon coalition between pro-life groups and animal rights activists that oppose this medical research on ethical grounds; the former seeking to ensure the welfare of human embryos and the latter seeking to protect the well-being of animals. Unlike the issue of abortion, this research is complex. Yet, it is important that the pro-life laity and clergy be adequately informed on some of the basic science and ethics that surround this research. To fully understand why this research is unethical and why the NIH is pursuing this particular research, it is important to understand the ethical tenets governing human-subject research and why secular scientists are pursuing this scientific field.

CTL epitope distribution patterns in the Gag and Nef proteins of HIV-1 from subtype A infected subjects in Kenya: Use of multiple peptide sets increases the detectable breadth of the CTL response

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Birx Deborah L

2006-04-01

Full Text Available Abstract Background Subtype A is a major strain in the HIV-1 pandemic in eastern Europe, central Asia and in certain regions of east Africa, notably in rural Kenya. While considerable effort has been focused upon mapping and defining immunodominant CTL epitopes in HIV-1 subtype B and subtype C infections, few epitope mapping studies have focused upon subtype A. Results We have used the IFN-γ ELIspot assay and overlapping peptide pools to show that the pattern of CTL recognition of the Gag and Nef proteins in subtype A infection is similar to that seen in subtypes B and C. The p17 and p24 proteins of Gag and the central conserved region of Nef were targeted by CTL from HIV-1-infected Kenyans. Several epitope/HLA associations commonly seen in subtype B and C infection were also observed in subtype A infections. Notably, an immunodominant HLA-C restricted epitope (Gag 296–304; YL9 was observed, with 8/9 HLA-CW0304 subjects responding to this epitope. Screening the cohort with peptide sets representing subtypes A, C and D (the three most prevalent HIV-1 subtypes in east Africa, revealed that peptide sets based upon an homologous subtype (either isolate or consensus only marginally improved the capacity to detect CTL responses. While the different peptide sets detected a similar number of responses (particularly in the Gag protein, each set was capable of detecting unique responses not identified with the other peptide sets. Conclusion Hence, screening with multiple peptide sets representing different sequences, and by extension different epitope variants, can increase the detectable breadth of the HIV-1-specific CTL response. Interpreting the true extent of cross-reactivity may be hampered by the use of 15-mer peptides at a single concentration and a lack of knowledge of the sequence that primed any given CTL response. Therefore, reagent choice and knowledge of the exact sequences that prime CTL responses will be important factors in

Efficient natural defense mechanisms against Listeria monocytogenes in T and B cell-deficient allogeneic bone marrow radiation chimeras. Preactivated macrophages are the main effector cells in an early phase after bone marrow transfer

International Nuclear Information System (INIS)

Roesler, J.; Groettrup, E.B.; Baccarini, M.; Lohmann-Mattes, M.L.

1989-01-01

Radiation chimeras in the early phase after bone marrow transplantation are a good model to study the efficiency of the body's nonspecific defense system represented by macrophages (M phi), polymorphonuclear cells (PMN), and NK cells. These cell types are present in large numbers in spleen and liver at that time, whereas the specific immune system represented by T and B cells is functionally deficient. We previously reported enhanced activities in vitro of M phi (and PMN) from recipient animals in an early phase after allogeneic bone marrow transfer. We here demonstrate that these activities result in enhanced spontaneous resistance against Listeria monocytogenes in vivo: CFU of L. monocytogenes in spleen and liver 48 h after infection were about 1 or 2 to 4 log steps less than in untreated control mice of donor or host haplotype. This enhanced resistance decreased over the 4-mo period after marrow transfer. Preactivated M phi were identified as the most important effector cells. Isolated from spleen and peritoneal cavity, they performed enhanced killing of phagocytosed Listeria. Such preactivated M phi occurred in recipient animals after transfer of allogeneic but not of syngeneic bone marrow. The precise mechanism of M phi activation in the allogeneic radiation chimera in the complete absence of any detectable T cell function is not clear at present. However, these preactivated M phi display an important protective effect against L. monocytogenes: chimeras could eliminate Listeria without acquisition of positive delayed-type sensitivity when infected with 10(3) bacteria. An inoculum of 5 . 10(3) L. monocytogenes resulted either in prolonged survival compared with normal mice of the recipient haplotype or in definitive survival accompanied by a positive delayed-type sensitivity

Understanding and Targeting Tumor Microenvironment in Prostate Cancer to Inhibit Tumor Progression and Castration Resistance

Science.gov (United States)

2016-10-01

cancer-secreted chemokine to attract Cxcr2-expressing MDSCs and, correspondingly, pharmacological inhibition of Cxcr2 impeded tumor progression...impact of pharmacological inhibition of Cxcl5 and Cxcr2 on MDSCs using the transwell migration assay 26 . First, anti-Cxcl5 neutralizing antibody...and MRI . (B) Generation of the CPPSML chimera model. (C) Fluorescence microscopy and H&E image of snap frozen prostate tumor from chimera showing that

New type of chimera and mutual synchronization of spatiotemporal structures in two coupled ensembles of nonlocally interacting chaotic maps

Science.gov (United States)

Bukh, Andrei; Rybalova, Elena; Semenova, Nadezhda; Strelkova, Galina; Anishchenko, Vadim

2017-11-01

We study numerically the dynamics of a network made of two coupled one-dimensional ensembles of discrete-time systems. The first ensemble is represented by a ring of nonlocally coupled Henon maps and the second one by a ring of nonlocally coupled Lozi maps. We find that the network of coupled ensembles can realize all the spatio-temporal structures which are observed both in the Henon map ensemble and in the Lozi map ensemble while uncoupled. Moreover, we reveal a new type of spatiotemporal structure, a solitary state chimera, in the considered network. We also establish and describe the effect of mutual synchronization of various complex spatiotemporal patterns in the system of two coupled ensembles of Henon and Lozi maps.

The Cucumber vein yellowing virus silencing suppressor P1b can functionally replace HCPro in Plum pox virus infection in a host-specific manner.

Science.gov (United States)

Carbonell, Alberto; Dujovny, Gabriela; García, Juan Antonio; Valli, Adrian

2012-02-01

Plant viruses of the genera Potyvirus and Ipomovirus (Potyviridae family) use unrelated RNA silencing suppressors (RSS) to counteract antiviral RNA silencing responses. HCPro is the RSS of Potyvirus spp., and its activity is enhanced by the upstream P1 protein. Distinctively, the ipomovirus Cucumber vein yellowing virus (CVYV) lacks HCPro but contains two P1 copies in tandem (P1aP1b), the second of which functions as RSS. Using chimeras based on the potyvirus Plum pox virus (PPV), we found that P1b can functionally replace HCPro in potyviral infections of Nicotiana plants. Interestingly, P1a, the CVYV protein homologous to potyviral P1, disrupted the silencing suppression activity of P1b and reduced the infection efficiency of PPV in Nicotiana benthamiana. Testing the influence of RSS in host specificity, we found that a P1b-expressing chimera poorly infected PPV's natural host, Prunus persica. Conversely, P1b conferred on PPV chimeras the ability to replicate locally in cucumber, CVYV's natural host. The deleterious effect of P1a on PPV infection is host dependent, because the P1aP1b-expressing PPV chimera accumulated in cucumber to higher levels than PPV expressing P1b alone. These results demonstrate that a potyvirus can use different RSS, and that particular RSS and upstream P1-like proteins contribute to defining the virus host range.

Molecular determinants of desensitization and assembly of the chimeric GABA(A) receptor subunits (alpha1/gamma2) and (gamma2/alpha1) in combinations with beta2 and gamma2

DEFF Research Database (Denmark)

Elster, L; Kristiansen, U; Pickering, D S

2001-01-01

Two gamma-aminobutyric acid(A) (GABA(A)) receptor chimeras were designed in order to elucidate the structural requirements for GABA(A) receptor desensitization and assembly. The (alpha1/gamma2) and (gamma2/alpha1) chimeric subunits representing the extracellular N-terminal domain of alpha1 or gamma......, as opposed to the staining of the (gamma2/alpha1)-containing receptors, which was only slightly higher than background. To explain this, the (alpha1/gamma2) and (gamma2/alpha1) chimeras may act like alpha1 and gamma2 subunits, respectively, indicating that the extracellular N-terminal segment is important...... for assembly. However, the (alpha1/gamma2) chimeric subunit had characteristics different from the alpha1 subunit, since the (alpha1/gamma2) chimera gave rise to no desensitization after GABA stimulation in whole-cell patch-clamp recordings, which was independent of whether the chimera was expressed...

Radiosensitive target in the early mouse embryo exposed to very low doses of ionizing radiation

International Nuclear Information System (INIS)

Wiley, Lynn M.; Raabe, Otto G.; Khan, Rakhshi; Straume, Tore

1994-01-01

We exposed mouse preimplantation embryos in vitro to either tritiated water (HTO) or tritiated thymidine (TdR) to determine whether the radiosensitive target was nuclear or extranuclear for embryonic cell proliferation disadvantage in the mouse embryo chimera assay. 8-cell embryos were incubated in either HTO or TdR for 2 h and paired with non-irradiated control embryos to form chimeras. Chimeras were cultured for an average of 20.2 h to allow for 2-3 cell cycles and then partially dissociated to obtain the number of progeny cells contributed by the two partner embryos for each chimera. These values were expressed as a 'proliferation ratio' (number of cells from the irradiated embryo: total number of cells in the chimera). A ratio significantly less than 0.50 indicates that the experimental embryo expressed an embryonic cell proliferation disadvantage, which is the endpoint of this assay. The activity concentrations of HTO and TdR were adjusted so that both would deliver comparable mean absorbed nuclear doses during the combined initial 2-h irradiation incubation and subsequent 20.2 h chimera incubation periods. Although nuclear doses were comparable under these conditions, the extranuclear dose delivered by the uniformly distributed HTO was about 100 times greater than the extranuclear dose delivered by TdR for each given nuclear dose. Consequently, obtaining mean TdR proliferation ratios≤mean HTO proliferation ratios would be evidence for a nuclear target while obtaining mean HTO proliferation ratios< mean TdR proliferation ratios would be evidence for an extranuclear target. TdR consistently produced lower mean proliferation ratios over a range of doses from 0.14 Gy to 0.43 Gy. Therefore, we conclude that the radiosensitive target for this endpoint is nuclear

Primordial Germ Cell-Mediated Chimera Technology Produces Viable Pure-Line Houbara Bustard Offspring: Potential for Repopulating an Endangered Species

Science.gov (United States)

Wernery, Ulrich; Liu, Chunhai; Baskar, Vijay; Guerineche, Zhor; Khazanehdari, Kamal A.; Saleem, Shazia; Kinne, Jörg; Wernery, Renate

2010-01-01

Background The Houbara bustard (Chlamydotis undulata) is a wild seasonal breeding bird populating arid sandy semi-desert habitats in North Africa and the Middle East. Its population has declined drastically during the last two decades and it is classified as vulnerable. Captive breeding programmes have, hitherto, been unsuccessful in reviving population numbers and thus radical technological solutions are essential for the long term survival of this species. The purpose of this study was to investigate the use of primordial germ cell-mediated chimera technology to produce viable Houbara bustard offspring. Methodology/Principal Findings Embryonic gonadal tissue was dissected from Houbara bustard embryos at eight days post-incubation. Subsequently, Houbara tissue containing gonadal primordial germ cells (gPGCs) was injected into White Leghorn chicken (Gallus gallus domesticus) embryos, producing 83/138 surviving male chimeric embryos, of which 35 chimeric roosters reached sexual maturity after 5 months. The incorporation and differentiation of Houbara gPGCs in chimeric chicken testis were assessed by PCR with Houbara-specific primers and 31.3% (5/16) gonads collected from the injected chicken embryos showed the presence of donor Houbara cells. A total of 302 semen samples from 34 chimeric roosters were analyzed and eight were confirmed as germline chimeras. Semen samples from these eight roosters were used to artificially inseminate three female Houbara bustards. Subsequently, 45 Houbara eggs were obtained and incubated, two of which were fertile. One egg hatched as a male live born Houbara; the other was female but died before hatching. Genotyping confirmed that the male chick was a pure-line Houbara derived from a chimeric rooster. Conclusion This study demonstrates for the first time that Houbara gPGCs can migrate, differentiate and eventually give rise to functional sperm in the chimeric chicken testis. This approach may provide a promising tool for propagation

Duct- and Acinar-Derived Pancreatic Ductal Adenocarcinomas Show Distinct Tumor Progression and Marker Expression

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Rute M.M. Ferreira

2017-10-01

Full Text Available The cell of origin of pancreatic ductal adenocarcinoma (PDAC has been controversial. Here, we show that identical oncogenic drivers trigger PDAC originating from both ductal and acinar cells with similar histology but with distinct pathophysiology and marker expression dependent on cell of origin. Whereas acinar-derived tumors exhibited low AGR2 expression and were preceded by pancreatic intraepithelial neoplasias (PanINs, duct-derived tumors displayed high AGR2 and developed independently of a PanIN stage via non-mucinous lesions. Using orthotopic transplantation and chimera experiments, we demonstrate that PanIN-like lesions can be induced by PDAC as bystanders in adjacent healthy tissues, explaining the co-existence of mucinous and non-mucinous lesions and highlighting the need to distinguish between true precursor PanINs and PanIN-like bystander lesions. Our results suggest AGR2 as a tool to stratify PDAC according to cell of origin, highlight that not all PanIN-like lesions are precursors of PDAC, and add an alternative progression route to the current model of PDAC development.

A genetically engineered live-attenuated simian-human immunodeficiency virus that co-expresses the RANTES gene improves the magnitude of cellular immunity in rhesus macaques

International Nuclear Information System (INIS)

Shimizu, Yuya; Inaba, Katsuhisa; Kaneyasu, Kentaro; Ibuki, Kentaro; Himeno, Ai; Okoba, Masashi; Goto, Yoshitaka; Hayami, Masanori; Miura, Tomoyuki; Haga, Takeshi

2007-01-01

Regulated-on-activation-normal-T-cell-expressed-and-secreted (RANTES), a CC-chemokine, enhances antigen-specific T helper (Th) type-1 responses against HIV-1. To evaluate the adjuvant effects of RANTES against HIV vaccine candidate in SHIV-macaque models, we genetically engineered a live-attenuated SHIV to express the RANTES gene (SHIV-RANTES) and characterized the virus's properties in vivo. After the vaccination, the plasma viral loads were same in the SHIV-RANTES-inoculated monkeys and the parental nef-deleted SHIV (SHIV-NI)-inoculated monkeys. SHIV-RANTES provided some immunity in monkeys by remarkably increasing the antigen-specific CD4 + Th cell-proliferative response and by inducing an antigen-specific IFN-γ ELISpot response. The magnitude of the immunity in SHIV-RANTES-immunized animals, however, failed to afford greater protection against a heterologous pathogenic SHIV (SHIV-C2/1) challenge compared to control SHIV-NI-immunized animals. SHIV-RANTES immunized monkeys, elicited robust cellular CD4 + Th responses and IFN-γ ELISpot responses after SHIV-C2/1 challenge. These findings suggest that the chemokine RANTES can augment vaccine-elicited, HIV-specific CD4 + T cell responses

Structure of 10Be and 16C nuclei via break-up reactions studied with the 4π Chimera array

Science.gov (United States)

Dell'Aquila, D.; Acosta, L.; Amorini, F.; Andolina, R.; Auditore, L.; Berceanu, I.; Cardella, G.; Chatterjiee, M. B.; De Filippo, E.; Francalanza, L.; Gnoffo, B.; Grzeszczuk, A.; Lanzalone, G.; Lombardo, I.; Martorana, N.; Minniti, T.; Pagano, A.; Pagano, E. V.; Papa, M.; Pirrone, S.; Politi, G.; Pop, A.; Porto, F.; Quattrocchi, L.; Rizzo, F.; Rosato, E.; Russotto, P.; Trifirò, A.; Trimarchi, M.; Verde, G.; Vigilante, M.

2018-01-01

The study of cluster states in neutron-rich Be and C isotopes is a subject of interest in Nuclear Physics. These states should be characterized by high deformation where α-clusters are bounded by valence neutrons. We performed a spectroscopic study of 10Be and 16C isotopes via projectile break-up reactions, by using radioactive beams produced at the INFN-LNS FRIBs facility and the Chimera 4π array. The possible evidence of a new 10Be state at 13.5 MeV excitation energy was found in the 6He+4He disintegration channel. The spectroscopy of 16C was studied via the 6He+10Be break-up channel; in this case we found the indication of a possible new state at about 20.6 MeV.

Chimeras Reveal a Single Lipid-Interface Residue that Controls MscL Channel Kinetics as well as Mechanosensitivity

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Li-Min Yang

2013-02-01

Full Text Available MscL, the highly conserved bacterial mechanosensitive channel of large conductance, serves as an osmotic “emergency release valve,” is among the best-studied mechanosensors, and is a paradigm of how a channel senses and responds to membrane tension. Although all homologs tested thus far encode channel activity, many show functional differences. We tested Escherichia coli and Staphylococcus aureus chimeras and found that the periplasmic region of the protein, particularly E. coli I49 and the equivalent S. aureus F47 at the periplasmic lipid-aqueous interface of the first transmembrane domain, drastically influences both the open dwell time and the threshold of channel opening. One mutant shows a severe hysteresis, confirming the importance of this residue in determining the energy barriers for channel gating. We propose that this site acts similarly to a spring for a clasp knife, adjusting the resistance for obtaining and stabilizing an open or closed channel structure.

Intrathymic T cell differentiation in radiation bone marrow chimeras and its role in T cell emigration to the spleen. An immunohistochemical study

International Nuclear Information System (INIS)

Hirokawa, K.; Sado, T.; Kubo, S.; Kamisaku, H.; Hitomi, K.; Utsuyama, M.

1985-01-01

Immunohistochemical studies were made on the regeneration of T cells of host- and donor-type in the thymus and spleen of radiation bone marrow chimeras by using B10- and B10.BR-Thy-1 congenic mice. In Thy-1 congenic chimeras, thymocytes of donor bone marrow origin, were first recognized at day 7, when the thymus involuted to the smallest size after the irradiation. The thymocytes of donor-type then proliferated exponentially, showing a slightly faster rate when higher doses of bone marrow cells were used for reconstitution, reaching a level of 100 million by day 17 and completely replacing the cortical thymocytes of host origin by day 21. The replacement of medullary thymocytes from host- to donor-type occurred gradually between days 21 and 35, after the replacement in the cortex was completed. In the spleen, about 1 million survived cells were recovered at day 3 after the irradiation, and approximately 60% of them were shown to be host-type T cells that were observed in the white pulp areas. The host-type T cells in the spleen increased gradually after day 10, due to the influx of host-type T cells from the regenerating thymus. Thus a pronounced increase of T cells of host-type was immunohistochemically observed in the splenic white pulp between days 21 and 28, when thymocytes of host-type were present mainly in the thymic medulla. These host-type T cells were shown to persist in the spleen for a long time, as long as 420 days after the treatment. Phenotypically, they were predominantly Lyt-1+2+ when examined at day 28, but 5 mo later, they were about 50% Lyt-1+2+ and 50% Lyt-1+2-

Visualization of the African swine fever virus infection in living cells by incorporation into the virus particle of green fluorescent protein-p54 membrane protein chimera

International Nuclear Information System (INIS)

Hernaez, Bruno; Escribano, Jose M.; Alonso, Covadonga

2006-01-01

Many stages of African swine fever virus infection have not yet been studied in detail. To track the behavior of African swine fever virus (ASFV) in the infected cells in real time, we produced an infectious recombinant ASFV (B54GFP-2) that expresses and incorporates into the virus particle a chimera of the p54 envelope protein fused to the enhanced green fluorescent protein (EGFP). The incorporation of the fusion protein into the virus particle was confirmed immunologically and it was determined that p54-EGFP was fully functional by confirmation that the recombinant virus made normal-sized plaques and presented similar growth curves to the wild-type virus. The tagged virus was visualized as individual fluorescent particles during the first stages of infection and allowed to visualize the infection progression in living cells through the viral life cycle by confocal microscopy. In this work, diverse potential applications of B54GFP-2 to study different aspects of ASFV infection are shown. By using this recombinant virus it was possible to determine the trajectory and speed of intracellular virus movement. Additionally, we have been able to visualize for first time the ASFV factory formation dynamics and the cytophatic effect of the virus in live infected cells. Finally, we have analyzed virus progression along the infection cycle and infected cell death as time-lapse animations

Expression of T cell antigen receptor genes in the thymus of irradiated mice after bone marrow transplantation

International Nuclear Information System (INIS)

Matsuzaki, G.; Yoshikai, Y.; Kishihara, K.; Nomoto, K.

1988-01-01

Sequential appearance of the expression of T cell antigen receptor genes was investigated in the thymus of irradiated mice at the early stage after transplantation of Thy-1 congeneic H-2 compatible allogeneic bone marrow cells. The first cells to repopulate the thymus on day 7 after bone marrow transplantation were intrathymic radioresistant T cell precursors, which expanded mainly to CD4+CD8+ host-type thymocytes by day 14. A high level of gamma gene expression but a much reduced level of alpha and beta gene expression were detected in the host-type thymocytes on day 7. During regeneration of these cells, gamma-chain messages fell to low level and alpha and beta mRNA levels increased. The thymus of the recipients began to be repopulated by donor-derived T cells about 2 wk after bone marrow transplantation and was almost completely replaced by the third week. An ordered expression of gamma then beta and alpha-chain gene transcript was also observed in the donor-type thymocytes at the early stage after bone marrow transplantation. The use of thymocytes at early stage in whole-body irradiated bone marrow chimera provides a pertinent source for investigating the molecular mechanism of T cell differentiation in adult thymus

Detection of Hepatitis C core antibody by dual-affinity yeast chimera and smartphone-based electrochemical sensing.

Science.gov (United States)

Aronoff-Spencer, Eliah; Venkatesh, A G; Sun, Alex; Brickner, Howard; Looney, David; Hall, Drew A

2016-12-15

Yeast cell lines were genetically engineered to display Hepatitis C virus (HCV) core antigen linked to gold binding peptide (GBP) as a dual-affinity biobrick chimera. These multifunctional yeast cells adhere to the gold sensor surface while simultaneously acting as a "renewable" capture reagent for anti-HCV core antibody. This streamlined functionalization and detection strategy removes the need for traditional purification and immobilization techniques. With this biobrick construct, both optical and electrochemical immunoassays were developed. The optical immunoassays demonstrated detection of anti-HCV core antibody down to 12.3pM concentrations while the electrochemical assay demonstrated higher binding constants and dynamic range. The electrochemical format and a custom, low-cost smartphone-based potentiostat ($20 USD) yielded comparable results to assays performed on a state-of-the-art electrochemical workstation. We propose this combination of synthetic biology and scalable, point-of-care sensing has potential to provide low-cost, cutting edge diagnostic capability for many pathogens in a variety of settings. Copyright © 2016 Elsevier B.V. All rights reserved.

Self-recognition specificity expressed by T cells from nude mice. Absence of detectable Ia-restricted T cells in nude mice that do exhibit self-K/D-restricted T cell responses

International Nuclear Information System (INIS)