495 research outputs found

    Study of the Nuclear Behavior in the Basidia and Basidiospores of \u3cem\u3eSchizophyllum commune\u3c/em\u3e Fries

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    Schizophyllum commune Fries is a member of the Hymeno­ mycetes. This genus has long intrigued mycologists because of the peculiar spliit gills\u27\u27 it characteristically possesses. For a long time, however, not much importance was attached to the fungus until it was reported from many parts or the world and its. pathogenicity as a wood-destroying agaric established. Despite these facts relatively little is known about the fungus. Perhaps the phase of development most completely described was the development of the gills , Essig (1922). Because of the location of the hymenium and stipe attachment, Essig (1922) suggested that the fungus more properly belongs in the family Thellephoraceae rather than the Agaricaceae; however, further work in the develop­ment of the fungus, especially the cytology, must properly be accomplished before such a change can be made. The cytological work on Schizophyllum is very incomplete, especially the cytology of the basidia; and many stages of development involving work in this field have not been demonstrated. Problems are presented by the exceedingly small nuclei, the small basidia, the hardness of the sporophore, difficulty in staining, and the difficulty of sectioning the sporophore thin enough for cytological investigation

    Rat cities and beehive worlds: density and design in the modern city

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    Nestled among E. M. Forster's careful studies of Edwardian social mores is a short story called "The Machine Stops." Set many years in the future, it is a work of science fiction that imagines all humanity housed in giant high-density cities buried deep below a lifeless surface. With each citizen cocooned in an identical private chamber, all interaction is mediated through the workings of "the Machine," a totalizing social system that controls every aspect of human life. Cultural variety has ceded to rigorous organization: everywhere is the same, everyone lives the same life. So hopelessly reliant is humanity upon the efficient operation of the Machine, that when the system begins to fail there is little the people can do, and so tightly ordered is the system that the failure spreads. At the story's conclusion, the collapse is total, and Forster's closing image offers a condemnation of the world they had built, and a hopeful glimpse of the world that might, in their absence, return: "The whole city was broken like a honeycomb. [⋯] For a moment they saw the nations of the dead, and, before they joined them, scraps of the untainted sky" (2001: 123). In physically breaking apart the city, there is an extent to which Forster is literalizing the device of the broken society, but it is also the case that the infrastructure of the Machine is so inseparable from its social structure that the failure of one causes the failure of the other. The city has-in the vocabulary of present-day engineers-"failed badly.

    H5N1 Whole-Virus Vaccine Induces Neutralizing Antibodies in Humans Which Are Protective in a Mouse Passive Transfer Model

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    BACKGROUND: Vero cell culture-derived whole-virus H5N1 vaccines have been extensively tested in clinical trials and consistently demonstrated to be safe and immunogenic; however, clinical efficacy is difficult to evaluate in the absence of wide-spread human disease. A lethal mouse model has been utilized which allows investigation of the protective efficacy of active vaccination or passive transfer of vaccine induced sera following lethal H5N1 challenge. METHODS: We used passive transfer of immune sera to investigate antibody-mediated protection elicited by a Vero cell-derived, non-adjuvanted inactivated whole-virus H5N1 vaccine. Mice were injected intravenously with H5N1 vaccine-induced rodent or human immune sera and subsequently challenged with a lethal dose of wild-type H5N1 virus. RESULTS: Passive transfer of H5N1 vaccine-induced mouse, guinea pig and human immune sera provided dose-dependent protection of recipient mice against lethal challenge with wild-type H5N1 virus. Protective dose fifty values for serum H5N1 neutralizing antibody titers were calculated to be ≤1∶11 for all immune sera, independently of source species. CONCLUSIONS: These data underpin the confidence that the Vero cell culture-derived, whole-virus H5N1 vaccine will be effective in a pandemic situation and support the use of neutralizing serum antibody titers as a correlate of protection for H5N1 vaccines

    A Whole Virus Pandemic Influenza H1N1 Vaccine Is Highly Immunogenic and Protective in Active Immunization and Passive Protection Mouse Models

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    The recent emergence and rapid spread of a novel swine-derived H1N1 influenza virus has resulted in the first influenza pandemic of this century. Monovalent vaccines have undergone preclinical and clinical development prior to initiation of mass immunization campaigns. We have carried out a series of immunogenicity and protection studies following active immunization of mice, which indicate that a whole virus, nonadjuvanted vaccine is immunogenic at low doses and protects against live virus challenge. The immunogenicity in this model was comparable to that of a whole virus H5N1 vaccine, which had previously been demonstrated to induce high levels of seroprotection in clinical studies. The efficacy of the H1N1 pandemic vaccine in protecting against live virus challenge was also seen to be equivalent to that of the H5N1 vaccine. The protective efficacy of the H1N1 vaccine was also confirmed using a severe combined immunodeficient (SCID) mouse model. It was demonstrated that mouse and guinea pig immune sera elicited following active H1N1 vaccination resulted in 100% protection of SCID mice following passive transfer of immune sera and lethal challenge. The immune responses to a whole virus pandemic H1N1 and a split seasonal H1N1 vaccine were also compared in this study. It was demonstrated that the whole virus vaccine induced a balanced Th-1 and Th-2 response in mice, whereas the split vaccine induced mainly a Th-2 response and only minimal levels of Th-1 responses. These data supported the initiation of clinical studies with the same low doses of whole virus vaccine that had previously been demonstrated to be immunogenic in clinical studies with a whole virus H5N1 vaccine

    Red Queen Coevolution on Fitness Landscapes

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    Species do not merely evolve, they also coevolve with other organisms. Coevolution is a major force driving interacting species to continuously evolve ex- ploring their fitness landscapes. Coevolution involves the coupling of species fit- ness landscapes, linking species genetic changes with their inter-specific ecological interactions. Here we first introduce the Red Queen hypothesis of evolution com- menting on some theoretical aspects and empirical evidences. As an introduction to the fitness landscape concept, we review key issues on evolution on simple and rugged fitness landscapes. Then we present key modeling examples of coevolution on different fitness landscapes at different scales, from RNA viruses to complex ecosystems and macroevolution.Comment: 40 pages, 12 figures. To appear in "Recent Advances in the Theory and Application of Fitness Landscapes" (H. Richter and A. Engelbrecht, eds.). Springer Series in Emergence, Complexity, and Computation, 201

    An integrated theoretical framework to enhance resource efficiency, sustainability and human health in agri-food systems

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    The absence of integrated decision-making across the agri-food system is arguably the single biggest obstacle to global food security and breaking through it is perhaps our biggest challenge. To date little research has been done which takes a fully integrated view to address this global challenge. Integrated decision making implies change across all parts of the diverse agri-food system, requiring an integrated assessment of all the processes involved from the ecology of the land through to nutrition and health. To address this research need, we propose a theoretical framework for integrated solutions based upon mapping of whole agri-food systems, their quantitative analysis based on enhanced life cycle assessment, the use of emergent data to catalyse viable and commercially attractive innovation and the free access of data to all stakeholders and in particular consumers as the principle engine for change. This integrated framework is conceptualised through theoretical development building from prior research. This theoretical framework involves an iterative methodology of four overlapping steps (Map, Analyse, Visualise and Share), namely the MAVS cycle. It gives a transparent advanced methodology and collaborative decision support to all stakeholders across the agri-food ecosystems. We hypothesize that this framework would provide a mechanism to break down the current barriers that prevent the integrated solutions absolutely necessary for global food security. We also theoretically position the perspective that it would break the “four walls” of information that reside within each organisation, fostering an open system that encourages a more democratized agri-food system, in which sustainability and resource efficiency are embedded
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