22 research outputs found

    Unauthorized Horizontal Spread in the Laboratory Environment: The Tactics of Lula, a Temperate Lambdoid Bacteriophage of Escherichia coli

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    We investigated the characteristics of a lambdoid prophage, nicknamed Lula, contaminating E. coli strains from several sources, that allowed it to spread horizontally in the laboratory environment. We found that new Lula infections are inconspicuous; at the same time, Lula lysogens carry unusually high titers of the phage in their cultures, making them extremely infectious. In addition, Lula prophage interferes with P1 phage development and induces its own lytic development in response to P1 infection, turning P1 transduction into an efficient vehicle of Lula spread. Thus, using Lula prophage as a model, we reveal the following principles of survival and reproduction in the laboratory environment: 1) stealth (via laboratory material commensality), 2) stability (via resistance to specific protocols), 3) infectivity (via covert yet aggressive productivity and laboratory protocol hitchhiking). Lula, which turned out to be identical to bacteriophage phi80, also provides an insight into a surprising persistence of T1-like contamination in BAC libraries

    Lateral injection of oxygen with the Bosporus plume - fingers of oxidizing potential in the Black Sea

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    Saline and warm Mediterranean water flowing through the Bosporus Strait maintains a permanent pycnocline with vertical separation of oxic (O(2)), suboxic (absence of O(2) and H(2)S), and anoxic (H(2)S) zones in the Black Sea. The stable suboxic zone implies restricted vertical mixing of the upper oxic and lower anoxic layers and limited vertical flux of oxygen that cannot balance the upward flux of sulfide. We report data that directly confirm massive lateral injections (>200 km from the Bosporus) of oxygen-enriched waters of the Bosporus plume, created by the mixing of shallow, cold, intermediate-layer Black Sea water with Mediterranean water. These plume waters are laterally injected into the oxic layer and, more importantly, into the suboxic and anoxic layers over several small vertical scales ("fingers" of similar to5 m) at water densities (sigma(1)) from 15.0 to 16.4. O(2) injection oxidizes Mn(II) to Mn(III,IV), which then oxidizes H(2)S. The onset of H(2)S detection occurs in deeper waters in the southwest (>170 m; sigma(1) approximate to 16.4) relative to the west central Black Sea (110 m; sigma(1) approximate to 16.2) and coincides with increased MnO(2) and S(8) formation in the southwest

    Precaution and Fairness: A Framework for Distributing Costs of Protection from Environmental Risks

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    While there is an extensive literature on how the precautionary principle should be interpreted and when precautions should be taken, relatively little discussion exists about the fair distribution of costs of taking precautions. We address this issue by proposing a general framework for deciding how costs of precautions should be shared, which consists of a series of default principles that are triggered according to desert, rights, and ability to pay. The framework is developed with close attention to the pragmatics of how distributions will affect actual behaviours. It is intended to help decision-makers think more systematically about distributional consequences of taking precautionary measures, thereby to improve decision-making. Two case studies—one about a ban on turtle fishing in Costa Rica, and one about a deep-sea mining project in Papua New Guinea—are given to show how the framework can be applied
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