1,631 research outputs found

    Genome sequence of the button mushroom Agaricus bisporus reveals mechanisms governing adaptation to a humic-rich ecological niche

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    Agaricus bisporus is the model fungus for the adaptation, persistence, and growth in the humic-rich leaf-litter environment. Aside from its ecological role, A. bisporus has been an important component of the human diet for over 200 y and worldwide cultivation of the "button mushroom" forms a multibillion dollar industry. We present two A. bisporus genomes, their gene repertoires and transcript profiles on compost andduringmushroomformation.The genomes encode a full repertoire of polysaccharide-degrading enzymes similar to that of wood-decayers. Comparative transcriptomics of mycelium grown on defined medium, casing-soil, and compost revealed genes encoding enzymes involved in xylan, cellulose, pectin, and protein degradation aremore highly expressed in compost. The striking expansion of heme-thiolate peroxidases and β-etherases is distinctive from Agaricomycotina wood-decayers and suggests a broad attack on decaying lignin and related metabolites found in humic acid-rich environment. Similarly, up-regulation of these genes together with a lignolytic manganese peroxidase, multiple copper radical oxidases, and cytochrome P450s is consistent with challenges posed by complex humic-rich substrates. The gene repertoire and expression of hydrolytic enzymes in A. bisporus is substantially different from the taxonomically related ectomycorrhizal symbiont Laccaria bicolor. A common promoter motif was also identified in genes very highly expressed in humic-rich substrates. These observations reveal genetic and enzymatic mechanisms governing adaptation to the humic-rich ecological niche formed during plant degradation, further defining the critical role such fungi contribute to soil structure and carbon sequestration in terrestrial ecosystems. Genome sequence will expedite mushroom breeding for improved agronomic characteristics

    Heavy ion collisions and AdS/CFT

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    We review some recent applications of the AdS/CFT correspondence to heavy ion collisions including a calculation of the jet quenching parameter in N=4 super-Yang-Mills theory and quarkonium suppression from velocity scaling of the screening length for a heavy quark-antiquark pair. We also briefly discuss differences and similarities between QCD and N=4 Super-Yang-Mills theory.Comment: Plenary talk given at Quark Matter 2006, Shanghai, China, 14-20 Nov 2006; to appear in the conference proceedin

    Governance, regulation and financial market instability: the implications for policy

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    Just as the 1929 Stock Market Crash discredited Classical economic theory and policy and opened the way for Keynesianism, a consequence of the collapse of confidence in financial markets and the banking system—and the effect that this has had on the global macro economy—is currently discrediting the ‘conventional wisdom’ of neo-liberalism. This paper argues that at the heart of the crisis is a breakdown in governance that has its roots in the co-evolution of political and economic developments and of economic theory and policy since the 1929 Stock Market Crash and the Great Depression that followed. However, while many are looking back to the Great Depression and to the theories and policies that seemed to contribute to recovery during the first part of the twentieth century, we argue that the current context is different from the earlier one; and there are more recent events that may provide better insight into the causes and contributing factors giving rise to the present crisis and to the implications for theory and policy that follow

    Trust in governance networks: Its impacts on outcomes

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    __Abstract__ Governance networks are characterized by complex interaction and decision making, and much uncertainty. Surprisingly, there is very little research on the impact of trust in achieving results in governance networks. This article asks two questions: (a) Does trust influence the outcomes of environmental projects? and (b) Does active network management improve the level of trust in networks? The study is based on a Web-based survey of respondents involved in environmental projects. The results indicate that trust does matter for perceived outcomes and that network management strategies enhance the level of trust

    Pre- and Posttranslational Regulation of Î’-Endorphin Biosynthesis in the CNS: Effects of Chronic Naltrexone Treatment

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    There appear to be two anatomically distinct Β-endorphin (ΒE) pathways in the brain, the major one originating in the arcuate nucleus of the hypothalamus and a smaller one in the area of the nucleus tractus solitarius (NTS) of the caudal medulla. Previous studies have shown that these two proopiomelanocortin (POMC) systems may be differentially regulated by chronic morphine treatment, with arcuate cells down-regulated and NTS cells unaffected. In the present experiments, we examined the effects of chronic opiate antagonist treatment on ΒE biosynthesis across different CNS regions to assess whether the arcuate POMC system would be regulated in the opposite direction to that seen after opiate agonist treatment and to determine whether different ΒE-containing areas might be differentially regulated. Male adult rats were administered naltrexone (NTX) by various routes for 8 days (subcutaneous pellets, osmotic minipumps, or repeated intraperitoneal injections). Brain and spinal cord regions were assayed for total ΒE-ir, different molecular weight immunoreactive Β-endorphin (ΒE-ir) peptides, and POMC mRNA. Chronic NTX treatment, regardless of the route of administration, reduced total ΒE-ir concentrations by 30–40% in diencephalic areas (the arcuate nucleus, the remaining hypothalamus, and the thalamus) and the midbrain, but had no effect on ΒE-ir in the NTS or any region of the spinal cord. At the same time, NTX pelleting increased POMC mRNA levels in the arcuate to ∼ 140% of control values. These data suggest that arcuate POMC neurons are up-regulated after chronic NTX treatment (whereas NTS and spinal cord systems remain unaffected) and that they appear to be under tonic inhibition by endogenous opioids. Chromatographic analyses demonstrated that, after chronic NTX pelleting, the ratio of full length ΒE 1–31 to more processed ΒE-ir peptides (i.e., ΒE 1–27 and ΒE 1–26 ) tended to increase in a dose-dependent manner in diencephalic areas. Because ΒE 1–31 is the only POMC product that possesses opioid agonist properties, and ΒE 1–27 has been posited to function as an endogenous anatgonist of ΒE 1–31 , the NTX-induced changes in the relative concentrations of ΒE 1–31 and ΒE 1–27 /ΒE 1–26 may represent a novel regulatory mechanism of POMC cells to alter the opioid signal in the synapse.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65603/1/j.1471-4159.1993.tb05820.x.pd
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