28 research outputs found

    Rigid Supersymmetric Theories in Curved Superspace

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    We present a uniform treatment of rigid supersymmetric field theories in a curved spacetime M\mathcal{M}, focusing on four-dimensional theories with four supercharges. Our discussion is significantly simpler than earlier treatments, because we use classical background values of the auxiliary fields in the supergravity multiplet. We demonstrate our procedure using several examples. For M=AdS4\mathcal{M}=AdS_4 we reproduce the known results in the literature. A supersymmetric Lagrangian for M=S4\mathcal{M}=\mathbb{S}^4 exists, but unless the field theory is conformal, it is not reflection positive. We derive the Lagrangian for M=S3×R\mathcal{M}=\mathbb{S}^3\times \mathbb{R} and note that the time direction R\mathbb{R} can be rotated to Euclidean signature and be compactified to §1\S^1 only when the theory has a continuous R-symmetry. The partition function on M=S3ק1\mathcal{M}=\mathbb{S}^3\times \S^1 is independent of the parameters of the flat space theory and depends holomorphically on some complex background gauge fields. We also consider R-invariant N=2\mathcal{N}=2 theories on S3\mathbb{S}^3 and clarify a few points about them.Comment: 26 pages, uses harvmac; v2 with added reference

    Monopoles, three-algebras and ABJM theories with N=5,6,8\N=5,6,8 supersymmetry

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    We extend the hermitian three-algebra formulation of ABJM theory to include U(1)U(1) factors. With attention payed to extra U(1)U(1) factors, we refine the classification of N=6\N=6 ABJM theories. We argue that essentially the only allowed gauge groups are SU(N)×SU(N)SU(N)\times SU(N), U(N)×U(M)U(N)\times U(M) and Sp(N)×U(1)Sp(N)\times U(1) and that we have only one independent Chern-Simons level in all these cases. Our argument is based on integrality of the U(1)U(1) Chern-Simons levels and supersymmetry. A relation between monopole operators and Wilson lines in Chern-Simons theory suggests certain gauge representations of the monopole operators. From this we classify cases where we can not expect enhanced N=8\N=8 supersymmetry. We also show that there are two equivalent formulations of N=5\N=5 ABJM theories, based on hermitian three-algebra and quaternionic three-algebra respectively. We suggest properties of monopoles in N=5\N=5 theories and show how these monopoles may enhance supersymmetry from N=5\N=5 to N=6\N=6.Comment: 52 page

    Gla-rich protein function as an anti-inflammatory agent in monocytes/macrophages: implications for calcification-related chronic inflammatory diseases

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    Calcification-related chronic inflammatory diseases are multifactorial pathological processes, involving a complex interplay between inflammation and calcification events in a positive feed-back loop driving disease progression. Gla-rich protein (GRP) is a vitamin K dependent protein (VKDP) shown to function as a calcification inhibitor in cardiovascular and articular tissues, and proposed as an anti-inflammatory agent in chondrocytes and synoviocytes, acting as a new crosstalk factor between these two interconnected events in osteoarthritis. However, a possible function of GRP in the immune system has never been studied. Here we focused our investigation in the involvement of GRP in the cell inflammatory response mechanisms, using a combination of freshly isolated human leucocytes and undifferentiated/differentiated THP-1 cell line. Our results demonstrate that VKDPs such as GRP and matrix gla protein (MGP) are synthesized and gamma-carboxylated in the majority of human immune system cells either involved in innate or adaptive immune responses. Stimulation of THP-1 monocytes/macrophages with LPS or hydroxyapatite (HA) up-regulated GRP expression, and treatments with GRP or GRP-coated basic calcium phosphate crystals resulted in the down-regulation of mediators of inflammation and inflammatory cytokines, independently of the protein gamma-carboxylation status. Moreover, overexpression of GRP in THP-1 cells rescued the inflammation induced by LPS and HA, by down-regulation of the proinflammatory cytokines TNF alpha, IL-1 beta and NFkB. Interestingly, GRP was detected at protein and mRNA levels in extracellular vesicles released by macrophages, which may act as vehicles for extracellular trafficking and release. Our data indicate GRP as an endogenous mediator of inflammatory responses acting as an anti-inflammatory agent in monocytes/macrophages. We propose that in a context of chronic inflammation and calcification-related pathologies, GRP might act as a novel molecular mediator linking inflammation and calcification events, with potential therapeutic application.Portuguese Science and Technology Foundation (FCT) [PTDC/SAU-ORG/117266/2010, PTDC/BIM-MEC/1168/2012, UID/Multi/ 04326/2013]; FCT fellowships [SFRH/BPD/70277/2010, SFRH/BD/111824/2015

    TILLING - a shortcut in functional genomics

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    Recent advances in large-scale genome sequencing projects have opened up new possibilities for the application of conventional mutation techniques in not only forward but also reverse genetics strategies. TILLING (Targeting Induced Local Lesions IN Genomes) was developed a decade ago as an alternative to insertional mutagenesis. It takes advantage of classical mutagenesis, sequence availability and high-throughput screening for nucleotide polymorphisms in a targeted sequence. The main advantage of TILLING as a reverse genetics strategy is that it can be applied to any species, regardless of its genome size and ploidy level. The TILLING protocol provides a high frequency of point mutations distributed randomly in the genome. The great mutagenic potential of chemical agents to generate a high rate of nucleotide substitutions has been proven by the high density of mutations reported for TILLING populations in various plant species. For most of them, the analysis of several genes revealed 1 mutation/200–500 kb screened and much higher densities were observed for polyploid species, such as wheat. High-throughput TILLING permits the rapid and low-cost discovery of new alleles that are induced in plants. Several research centres have established a TILLING public service for various plant species. The recent trends in TILLING procedures rely on the diversification of bioinformatic tools, new methods of mutation detection, including mismatch-specific and sensitive endonucleases, but also various alternatives for LI-COR screening and single nucleotide polymorphism (SNP) discovery using next-generation sequencing technologies. The TILLING strategy has found numerous applications in functional genomics. Additionally, wide applications of this throughput method in basic and applied research have already been implemented through modifications of the original TILLING strategy, such as Ecotilling or Deletion TILLING
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