10 items with the tag “molybdenum

  • Stoichiometry of Life, Task 1: Laboratory Studies in Biological Stoichiometry
    NAI 2009 Arizona State University Annual Report

    Living things require a broad menu of chemical elements to function. This project aims to quantify the chemical elements required by prokaryotes – the class of terrestrial organisms thought most similar to those that might be present in extraterrestrial settings – through laboratory experiments. These experiments will also teach us the ways in which such organisms cope with scarcity of the bioessential elements nitrogen, phosphorus and iron. We are also conducting experiments to isolate micro-organisms that use the element arsenic in place of phosphorus, if they exist. In Year 1 we initiated the first stage of these experiments.

    ROADMAP OBJECTIVES: 5.1 5.2 5.3 6.1 6.2 7.1
  • Stoichiometry of Life - Task 1e- Experimental Studies - Diatom Growth on Iron Nanoparticles
    NAI 2010 Arizona State University Annual Report

    In some environments (such as ocean regions fed by icebergs), the critical element iron (Fe) is supplied in the form of very small (“nano”) particles that are suspended rather than dissolved in water. However, it’s not known if this nanoparticle Fe is available to microscopic phytoplankton. This project involves experiments testing whether diatoms (a key oceanic phytoplankton group) can access nanoparticle Fe.

    ROADMAP OBJECTIVES: 6.1
  • Stoichiometry of Life - Task 1d - Experimental Studies - the Role of Molybdenum in the Nitrogen Cycle, Past and Present
    NAI 2010 Arizona State University Annual Report

    The element molybdenum (Mo) is critical for key processes in the cycling of nitrogen (N); for example, it is essential for the enzyme nitrogenase which bacteria use to convert gaseous N to “fixed” N that can be used in biological processes. This project seeks to understand how Mo might limit N processing in modern ecosystems (lakes and oceans) and infer its potential role in the past.

    ROADMAP OBJECTIVES: 4.1 5.1 6.1
  • Stoichiometry of Life - Task 1b - Experimental Studies - Microbial Production of Exopolymeric Subtances (EPS)
    NAI 2010 Arizona State University Annual Report

    One way that microscopic plankton affect the Earth system is by producing carbon compounds that can sink to the bottom of the ocean, thus burying C for extended periods. The production of “exopolymeric substances” (EPS), sticky molecules often made from sugars, is such a mechanism. This project seeks to determine some of the basic parameters that affect the production of EPS by marine phytoplankton.

    ROADMAP OBJECTIVES: 4.1 6.1
  • Stoichiometry of Life - Task 2c - Biological Soil Crusts: Metal Use and Acquisition
    NAI 2011 Arizona State University Annual Report

    Desert biological soil crusts (BSCs) are a complex consortia of microorganisms including cyanobacteria, algae, and fungi. BSCs are the primary colonizers of desert soils, supplying both carbon and nitrogen to these arid-land ecosystems. As such, they may represent an analog for soil development on the early Earth. BSCs occupy an extremely nutrient-poor niche, and meet their nutrient and metal requirements by manipulating their surroundings via the production of metal-binding ligands called siderophores. The soil crust’s metabolism affects the chemical composition of soil porewaters and soil solid phases; these alterations to soil metal contents may represent a biosignature for biological soil crusts that can be preserved over long time scales.

    ROADMAP OBJECTIVES: 4.1 5.3 6.1 6.2 7.1
  • Stoichiometry of Life - Task 1 - Laboratory Studies in Biological Stoichiometry
    NAI 2011 Arizona State University Annual Report

    This project component involves a diverse set of studies of various microorganisms with which we are trying to better understand how living things use chemical elements (nitrogen, phosphorus, iron, etc) and how they cope, in a physiological sense, with shortages of such elements. For example, how does the “elemental recipe of life” change when an organism is starved for phosphorus? Is this change similar for diverse species of microorganisms? Are the changes the same if the organism is limited by a different key nutrient? Furthermore, how does an organism shift its patterns of gene expression when it is starved by various nutrients? This will help in interpreting studies of gene expression in natural environments. At an even more profound level: can an organism substitute an element that is similar to the one that is limiting, as in the case of arsenic for phosphorus?

    ROADMAP OBJECTIVES: 5.2 5.3 6.1 6.2
  • Stoichiometry of Life - Task 1 - Laboratory Studies in Biological Stoichiometry
    NAI 2012 Arizona State University Annual Report

    This project component involves a diverse set of studies of various microorganisms with which we are trying to better understand how living things use chemical elements (nitrogen, phosphorus, iron, etc) and how they cope, in a physiological sense, with shortages of such elements. For example, how does the “elemental recipe of life” change when an organism is starved for phosphorus or nitrogen or iron? Is this change similar for diverse species of microorganisms? Furthermore, how does an organism shift its patterns of gene expression when it is starved by various nutrients? This will help in interpreting studies of gene expression in natural environments, including extreme environments relevant to astrobiology.

    ROADMAP OBJECTIVES: 5.2 5.3 6.1 6.2