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  • 1
    Electronic Resource
    Electronic Resource
    Anaerobic biosynthesis of unsaturated fatty acids in the cyanobacterium, Oscillatoria limnetica (1989)
    Springer
    Archives of microbiology 152 (1989), S. 215-217 
    Details
    ISSN: 1432-072X
    Keywords: Cyanobacterium ; Oscillatoria limnetica ; Anacrobic unsaturated fatty acid synthesis ; Positional isomers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The mechanism for synthesis of monounsaturated fatty acids under aerobic and anaerobic conditions was studied in the facultative anaerobic cyanobacterium, Oscillatoria limnetica. The hexadecenoic acid (C16∶1) of aerobically grown O. limnetica was shown to contain both the Δ7 (79%) and Δ9 (21%) isomers, while the octadecenoic (C18∶1) acid was entirely the Δ9 acid. Incorporation of [2-14C] acetate into the fatty acids under aerobic conditions resulted in synthesis of the Δ7 and Δ9 C16∶1 and the Δ9 C18∶1. Synthesis of unsaturated fatty acids in the presence of DCMU required sulfide. Anaerobic incubations in the presence of DCMU and sulfide (less than 0.003% atmospheric oxygen) resulted in a two-fold increase in monounsaturated fatty acids of both Δ7 and Δ9 C16∶1 and Δ9 and Δ11 C18∶1. The synthesis of these isomers is characteristic of a bacterialtype, anaerobic pathway.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00409653
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  • 2
    Electronic Resource
    Electronic Resource
    The isolation of DNA-containing particles from lyophilized cells by a new procedure
    Amsterdam : Elsevier
    Analytical Biochemistry 2 (1961), S. 513-520 
    Details
    ISSN: 0003-2697
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/0003-2697(61)90018-5
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  • 3
    Electronic Resource
    Electronic Resource
    Studies of Elodea nuttallii grown under photorespiratory conditions. I. Photosynthetic characteristics (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 14 (1991), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract. The photosynthetic characteristics of Elodea nuttallii grown in wastewater in continuous flow reactors in a greenhouse were investigated. The diurnal changes in dissolved inorganic carbon (DIC), dissolved oxygen (DO) and pH were monitored. Photosynthesis removed both CO2(aq) and HCO3− from the reactors. A stoichiometry of 1.19:1 was observed between HCO3− removal during photosynthesis and OH− production during photosynthesis, consistent with theories regarding direct bicarbonate utilization. In laboratory experiments, the light compensation points (гPPFD) were similar (31–35μmol m−2 s−1) to reported values for other macrophytes; however, the light saturation level was high (1100μmol m−2 s−1) and similar to values reported for aerial portions Of heterophyllous macrophytes. The kinetics of photosynthetic oxygen evolution (Km (CO2) = 96mmol m−3; Vmax= 133mmol g−1 Chl h−1) and the CO2 compensation point (г= 44cm3 m−3) suggested an adaptive, low photorespiratory state in response to low carbon concentrations. Photosynthetic Vmax values were slightly, but significantly higher (P 0.001) at pH 8.0 compared to pH 4.5. While CO2 utilization at pH 8 could account for most of the observed phototsynthetic rates, an HCO3− component was present, suggesting two separate transport systems for HCO3− and CO2(aq) in E. nuttallii. The activity of RUBISCO (160.3 mmol g−1 Chl h−1 was one of the highest reported values for aquatic macrophytes. Compared to RUBISCO, we observed lower activities of the β-carboxylating enzymes phopho enolpyruvate carboyxlase (PEPcase), 24.1 mmol g−1 Chl h−1; phosphor enol pyruvate carboxykinase (PEPCKase), 14 mmol g−1 Chl h−1. This suggests that the potential light-independent fixation of carbon in E. nuttallii was much less than RUBISCO-dependent fixation. The RUBISCO/PEPcase ratio was 6.6, indicating that E. nuttallii was similar to Myriophyllum sp. in possessing a physiological adaptation to low CO2 levels which is hypothesized to include carbonic anhydrase (CA) and an active transport system for HCO3−. CA levels were surprisingly low in E. nuttallii (14.2 EUmg Chl−).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3040.1991.tb01331.x
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  • 4
    Electronic Resource
    Electronic Resource
    Studies of Elodea nuttallii grown under photorespiratory conditions. II. Evidence for bicarbonate active transport (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 14 (1991), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract. Elodea nuttallii was grown under greenhouse conditions in domestic wastewater in an aquatic treatment system under conditions conducive to photorespiration. Initial research on the photosynthetic characteristics of E. nuttallii suggest that the submergent macrophyte possessed a carbon concentrating mechanism. Isotopic disequilibria H14CO3-uptake studies (5-80s) were used to assess the bicarbonate active-transport capabilities in E. nuttallii leaves. Using a range of substrate concentrations (50-50200mmol m−3), the accumulation of label (mmol g−1 Chl) over time due to transport was found initially to exceed accumulation due to fixation until steady state rates were observed. Internal steady state pools of dissolved inorganic carbon (DIC) ranged from 40 to 80 mol m−3. The concentration factor (CF: the ratio of internal cyroplasmic (DIC] to external medium [DIC]) decreased from 800 to 114 as external bicarbonate concentrations were increased. Inhibition of transport by uncouplers (2,4-dinitrophenol (DNP), carbonyl cyanide-m-chlorophenylhydrazone (CCCP)); ATPase inhibitors (dicylcohexocarbodiamide (DCCD), phloridzin, arsenate); electron transport inhibitors (DCMU, Antimycin A), and carbonic anhydrase inhibitors (ethoxyzolamide, acetazolamide) suggest that bicarbonate transport required (1) a proton motive force, (2) a functional ATPase, (3) a chloroplast carbon sink, and possibly (4) a CA-like moiety associated with the transport protein. While plasmalemmasomes were not observed, the plasmalemma was vesiculated and acid and alkaline banding was observed when leaves were incubated under light in the presence of bicarbonate. These data are consistent with the operation of a bicarbonate-cation symport which concentrates substrate against a concentration gradient at the expense of metabolic energy. The presence of an active transport system for bicarbonate ensures that internal carbon concentrations are high when carbon dioxide, is scarce and bicarbonate is the only carbon species available in aquatic treatment systems during photorespiratory conditions. Therefore, E. nuttallii is particularly well suited for use in these systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3040.1991.tb01332.x
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  • 5
    Electronic Resource
    Electronic Resource
    Studies of Elodea nuttallii grown under photorespiratory conditions. III. Quantitative cytological characteristics (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 14 (1991), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract. Elodea nuttallii was grown in primary effluent from domestic wastewater under conditions in which CO2 may be limiting. However, high photosynthetic inorganic carbon uptake rates have been reported for Elodea under these conditions. In order to determine if leaf cell structure showed modifications which would support proposed models of a plasma membrane (PM) bicarbonate transport system and observed high photo-synthetic rates, leaf cell ultrastructure was analysed using quantitative techniques (stereology). A Fold Index (FI) calculated for the PM showed that infolding increased surface area to 2.15 times that of an idealized cell of the same shape and size. Association Indices (Sa) showed a significant association of the mitochondria with the PM. These observations support models for an ATPase-driven HCO3-cation cotransport system in Elodea cells. High chloroplast thylakoid surface density values (Sv) were similar to C4:monocots and indicated high light-gathering potential. The granal/stromal (g/s), granal/cristae (g/c), and stromal/cristae (s/c) membrane ratios were similar to those of C3 plant cells. Thus, Elodea chloroplasts and cells exhibited some structural features similar to both C3 and C4 plants. Membrane-bound inclusion bodies, which occupied 1% of the cell volume, were also observed in the leaf cells. Cell walls and nucleoid regions were absent in these bodies and X-ray (EDAX) analysis failed to detect any element (above the resolution limit of atomic no. 12) in substantial quantities. Inclusion bodies were observed in both the cytoplasm and the periplast and remain unidentified. A model is proposed for Elodea using an ATPase proton pump in the plasma membrane which extrudes protons into the periplast space between the cell wall and plasma membrane. This proton gradient is coupled to a bicarbonate symport.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3040.1991.tb01333.x
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  • 6
    Electronic Resource
    Electronic Resource
    Chilling stress and oxygen metabolizing enzymes in Zea mays and Zea diploperennis (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 14 (1991), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract. The activities of five active-oxygen scavenging enzymes were compared for cold-lability and three were compared for chilling induction in two Zea genotypes of contrasting susceptibility to photoinhibition during chilling. Activities of superoxide dismutase (SOD, EC 1.15.1.1), ascorbate peroxidase (APX, EC 1.11.1.11), monodehydroascorbate reductase (MDHAR, EC 1.6.5.4), dehydroascorbate reductase (DHAR, EC 1.8.5.1), and glutathione reductase (GTR, EC 1.6.4.2) in leaf extracts from plants grown without chilling stress were assayed at 19°C and 5°C. Enzymes from the chilling-susceptible Z. Mays cv. LG11 had lower specific activities at 5°C than did enzymes from the chilling-tolerant Z. diploperennis, except for MDHAR where no significant differences were observed. The activities of SOD and APX from Z. diploperennis were double those of Z. mays at both assay temperatures. Monodehydroa-scrobate reductase and glutathione reductase activities in both species were reduced by 63–78% at a 5°C assay temperature. The dehydroascorbate reductase (DHAR) showed the greatest low-temperature lability losing 96% (Z. diploperennis) and 100% (Z. mays) of its activity at 5°C. To examine possible chilling-induced changes in levels of enzyme activity, plants of both Zea genotypes were transferred to growth chambers at 10°C at moderate light intensities. Glutathione reductase activity was found to increase within 24h in Z. diploperennis, but it decreased slightly in Z. mays. MDHAR activity decreased by 50% in Z. diploperennis but showed only a transient increase in activity in Z. mays.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3040.1991.tb01375.x
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  • 7
    Electronic Resource
    Electronic Resource
    Biomarkers as tracers for life on early earth and mars (1996)
    Springer
    Origins of life and evolution of the biospheres 26 (1996), S. 515-516 
    Details
    ISSN: 1573-0875
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02459903
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  • 8
    Electronic Resource
    Electronic Resource
    Biomarkers as Tracers for Life on Early Earth and Mars (1998)
    Springer
    Origins of life and evolution of the biospheres 28 (1998), S. 475-483 
    Details
    ISSN: 1573-0875
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Biomarkers in geological samples are products derived from biochemical (natural product) precursors by reductive and oxidative processes (e.g., cholestanes from cholesterol). Generally, lipids, pigments and biomembranes are preserved best over longer geological times and labile compounds such as amino acids, sugars, etc. are useful biomarkers for recent times. Thus, the detailed characterization of biomarker compositions permits the assessment of the major contributing species of extinct and/or extant life. In the case of the early Earth, work has progressed to elucidate molecular structure and carbon isotopic signals preserved in ancient sedimentary rocks. In addition, the combination of bacterial biochemistry with the organic geochemistry of contemporary and ancient hydrothermal ecosystems permits the modeling of the nature, behavior and preservation potential of primitive microbial communities. This approach uses combined molecular and isotopic analyses to characterize lipids produced by cultured bacteria (representative of ancient strains) and to test a variety of culture conditions which affect their biosynthesis. On considering Mars, the biomarkers from lipids and biopolymers would be expected to be preserved best if life flourished there during its early history (3.5–4 × 109 yr ago). Both oxidized and reduced products would be expected. This is based on the inferred occurrence of hydrothermal activity during that time with the concomitant preservation of biochemically-derived organic matter. Both known biomarkers (i.e., as elucidated for early terrestrial samples and for primitive terrestrial microbiota) and novel, potentially unknown compounds should be characterized.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006508012904
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  • 9
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    Intracellular localization of a group II chaperonin indicates a membrane-related function (2003)
    National Academy of Sciences
    Details
    Publication Date: 2003-12-12
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
    Published by National Academy of Sciences
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  • 10
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    Agreement of Experiment and Theory on the Single Ionization of Helium by Fast Proton Impact (2016)
    American Physical Society (APS)
    Details
    Publication Date: 2016-02-19
    Description: Author(s): H. Gassert, O. Chuluunbaatar, M. Waitz, F. Trinter, H.-K. Kim, T. Bauer, A. Laucke, Ch. Müller, J. Voigtsberger, M. Weller, J. Rist, M. Pitzer, S. Zeller, T. Jahnke, L. Ph. H. Schmidt, J. B. Williams, S. A. Zaytsev, A. A. Bulychev, K. A. Kouzakov, H. Schmidt-Böcking, R. Dörner, Yu. V. Popov, and M. S. Schöffler High resolution measurements of the electron emission pattern following the ionization of helium settles a decade old discrepancy between theory and experiment on the angular emission pattern. [Phys. Rev. Lett. 116, 073201] Published Wed Feb 17, 2016
    Keywords: Atomic, Molecular, and Optical Physics
    Print ISSN: 0031-9007
    Electronic ISSN: 1079-7114
    Topics: Physics
    Published by American Physical Society (APS)
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