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  • 1
    Electronic Resource
    Electronic Resource
    Pathway and products of CO2-fixation by green prokaryotic algae in the cloacal cavity of Diplosoma virens (1978)
    Springer
    Marine biology 47 (1978), S. 325-330 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Light-dependent 14CO2 fixation by the algae of Diplosoma virens (Hartmeyer) ranged between about 3 and 27 μmoles mg-1 chlorophyll h-1. The principal first products of 14C fixation were 3-phosphoglyceric acid and phosphorylated sugars, indicating that ribulose bisphosphate carboxylase was the primary carboxylation enzyme. The activity of this enzyme in crude extracts of the algae was 4 to 6 μmoles CO2 mg-1 chlorophyll h-1. The principal end product of 14C fixation by these algae in the ascidian host was a water-soluble oligosaccharide which was an α-1,4-glucan. A maximum of 7% of the 14C fixed was found in insoluble materials of the algae or its host after 60 min 14CO2 fixation. Whether the α-1,4-glucan is a product of algal or animal metabolism remains to be determined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00388923
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  • 2
    Electronic Resource
    Electronic Resource
    Coupling of ion transport in green cells ofAtriplex spongiosa leaves to energy sources in the light and in the dark (1970)
    Springer
    The journal of membrane biology 2 (1970), S. 17-30 
    Details
    ISSN: 1432-1424
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary The coupling of ion transport to energy sources in the light and in the dark in green cells ofAtriplex spongiosa leaves was investigated using light of different qualities, an inhibitor of electron transport (dichlorophenyl dimethyl urea), and an uncoupler (p-CF3O-carbonyl cyanide phenylhydrazone). Two different mechanisms of ion uptake were, distinguished. (1) A light-dependent Cl− pump which is linked to light-dependent K+ uptake. The energy for this pump is probably derived from photosynthetic electron transport or from nicotinamide adenine dinucleotide phosphate, reduced form. This mechanism is dichlorophenyl dimethyl urea-sensitive and enhanced by uncouplers. (2) A mechanism independent of light, which operates at the same rate in the light and in the dark. This mechanism is sensitive to uncouplers. It is probably aK−Na exchange mechanism since K+ and Cl− uptake and a small net uptake of H+ are balanced by Na+ loss.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01869847
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  • 3
    Electronic Resource
    Electronic Resource
    Effect of poly-L-lysine on potassium fluxes in red beet tissue (1970)
    Springer
    The journal of membrane biology 2 (1970), S. 85-94 
    Details
    ISSN: 1432-1424
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary Poly-L-lysine concentrations (10−6 m) which cause slight leakage of pigment from beet cells completely disrupt the kinetics of*K (labeled) absorption at 25°C in the range 0.01 to 50mm KCl. Lower concentrations of polylysine (10−7 to 10−9 m) interfere with potassium fluxes at both cell membranes, initially increasing efflux across the plasma membrane and decreasing the capacity of the cytoplasm to retain ions during flux experiments at 2°C. At 25°C, these concentrations of polylysine increase*K (labeled) absorption from 0.2mm KCl, but not from 10mm KCl. These responses are discussed in relation to ion transport via the three-compartment in-series model proposed for plant cells. Particular emphasis is placed on the role of the plasma membrane in K transport from solutions of low concentration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01869852
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  • 4
    Electronic Resource
    Electronic Resource
    Crassulacean Acid Metabolism: A Curiosity in Context (1978)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Plant Physiology 29 (1978), S. 379-414 
    Details
    ISSN: 0066-4294
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1146/annurev.pp.29.060178.002115
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  • 5
    Electronic Resource
    Electronic Resource
    Rapid changes in xanthophyll cycle-dependent energy dissipation and photosystem II efficiency in two vines, Stephania japonica and Smilax australis, growing in the understory of an open Eucalyptus forest (1999)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 22 (1999), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Leaves of Stephania japonica and Smilax australis were characterized in situ on the coast of north-eastern New South Wales, Australia, where they were growing naturally in three different light environments: deep shade, in the understory of an open Eucalyptus forest where they received frequent sunflecks of high intensity, and in an exposed site receiving full sunlight. In deep shade the xanthophyll cycle remained epoxidized during the day and the vast majority of absorbed light was utilized for photosynthesis. In the exposed site both deepoxidation and epoxidation of the xanthophyll cycle and changes in the level of xanthophyll-dependent thermal energy dissipation largely tracked the diurnal changes in photon flux density (PFD). In the understory the xanthophyll cycle became largely deepoxidized to zeaxanthin and antheraxanthin upon exposure of the leaves to the first high intensity sunfleck and this high level of deepoxidation was maintained throughout the day both during and between subsequent sunflecks. In contrast, thermal energy dissipation activity, and the efficiency of photosystem II, fluctuated rapidly in response to the changes in incident PFD. These findings suggest a fine level of control over the engagement of zeaxanthin and antheraxanthin in energy dissipation activity, presumably through rapid changes in thylakoid acidification, such that they became rapidly engaged for photoprotection during the sunflecks and rapidly disengaged upon return to low light when continued engagement might limit carbon gain.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-3040.1999.00369.x
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  • 6
    Electronic Resource
    Electronic Resource
    dr and spr/sr mutations of Chlamydomonas reinhardtii affecting D1 protein function and synthesis define two independent steps leading to chronic photoinhibition and confer differential fitness (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 20 (1997), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The effects of introduced chloroplast gene mutations affecting D1 synthesis, turnover and function on photosynthesis, growth and competitive ability were examined in autotrophic cultures of Chlamydomonas reinhardtii (Chlorophyta) adapted to low or high irradiance. Few discernible effects were evident when the mutants were grown in low light (LL, 70 μmol m−2 s−1). The herbicide-resistant psbA mutation Ser264→ Ala (dr) slowed electron transfer and accelerated D1 degradation in cells grown under high light (HL, 600 μmol m−2 s−1). The maximum rate of light-and CO2-saturated photosynthesis, cell growth rate and competitive ability in the dr mutant were reduced compared to wild type under HL. However, the wild-type rate of D1 synthesis in dr was adequate to compensate for accelerated D1 degradation. 16S rRNA mutations conferring resistance to streptomycin and spectinomycin (spr/sr) that altered chloroplast ribosome structure and assembly were used to inhibit chloroplast protein synthesis. In spr/sr cells grown under HL, D1 synthesis was reduced by 40–60% compared to wild type and D1 degradation was accelerated, leading to a 4-fold reduction in D1 pool size. The reduced D1 levels were accompanied by an elevation of Fo and a decline in Fv/Fm, quantum yield and maximum rate of CO2-saturated photosynthesis. Chemostat experiments showed that the growth rate and competitive ability of spr/sr were reduced against both wild type and dr.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-3040.1997.d01-143.x
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  • 7
    Electronic Resource
    Electronic Resource
    Isotopic heterogeneity of water in transpiring leaves: identification of the component that controls the δ18O of atmospheric O2 and CO2 (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 17 (1994), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Two direct but independent approaches were developed to identify the average δ18O value of the water fraction in the chloroplasts of transpiring leaves. In the first approach, we used the δ18O value of CO2 in isotopic equilibrium with leaf water to reconstruct the δ18O value of water in the chloroplasts. This method was based on the idea that the enzyme carbonic anhydrase facilitates isotopic equilibrium between CO2 and H2O predominantly in the chloroplasts, at a rate that is several orders of magnitude faster than the non-catalysed exchange in other leaf water fractions. In the second approach, we measured the δ18O value of O2 from photosynthetic water oxidation in the chloroplasts of intact leaves. Since O2 is produced from chloroplast water irreversibly and without discrimination, the δ18O value of the O2 should be identical to that of chloroplast water. In intact, transpiring leaves of sunflower (Helianthus annuus cv. giant mammoth) under the experimental conditions used, the average δ18O value of chloroplasts water was displaced by 3—10 % (depending on relative humidity and atmospheric composition) below the value predicted by the conventional Craig & Gordon model. Furthermore, this δ18O value was always lower than the δ18O value that was measured for bulk leaf water. Our results have implications for a variety of environmental studies since it is the δ18O value of water in the chloroplasts that is the relevant quantity in considering terrestrial plants influence on the δ18O values of atmospheric CO2 and O2, as well as in influencing the δ18O of plant organic matter.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3040.1994.tb00267.x
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  • 8
    Electronic Resource
    Electronic Resource
    Concepts of plant biotic stress. Some insights into the stress physiology of virus-infected plants, from the perspective of photosynthesis (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 100 (1997), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The consequences of biotic stress have been poorly understood, partly because its application is difficult to control and partly because its physiological consequences are highly variable. Many plant viruses are recognised on the basis of leaf symptoms that depend on localised changes to chloroplast structure and function. This paper reviews recent progress in understanding early interactions between plant viruses and the photosynthetic apparatus, using chlorophyll fluorescence analysis of novel, defined algal-virus systems and using high resolution imaging of chlorophyll fluorescence and other photosynthetic processes in higher plant systems. We then consider the consequences of viral effects on photosynthetic functioning for whole plants and populations with an emphasis on the potential interactions with other environmental factors. Early responses indicated by increase in both non-photochemical quenching of fluorescence and increased reduction state of the primary electron transport acceptor QA suggest that, not surprisingly, both photoprotective and photoinhibitory processes contribute to the accelerated local demise of the photosynthetic apparatus and symptom development. In other cases, localised accumulations of carbohydrate and source-sink imbalance following infection may inhibit gene expression, leading to altered levels of chloroplast protein complexes and enzymes of photosynthetic metabolism coincident with symptom development. Recent experiments suggest that much of the variability in plant responses to biotic stress may result from interactions with other environmental factors, such as light intensity and nutrition. Experiments suggest that virus infections may have greater effects on fitness and competitive ability in low N, high light environments than in shaded, high nutrient conditions. Some ecological implications of these observations are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1997.tb04776.x
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  • 9
    Electronic Resource
    Electronic Resource
    Stomatal mechanism as the basis of evolution of crassulacean acid metabolism (1985)
    [s.l.] : Nature Publishing Group
    Nature 314 (1985), S. 200-200 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] KEELEY ET AL. REPLY-We agree with Cockburn that, although the presence of CAM in astomatous Stylites does not support his theory on the stomatal origin of CAM, it does not necessarily falsify the theory either. We also agree with Thomas that Stylites most reasonably should be included with ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/314200c0
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  • 10
    Electronic Resource
    Electronic Resource
    Australian universities (1995)
    [s.l.] : Nature Publishing Group
    Nature 376 (1995), S. 630-630 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] SIR - If one does not manipulate the numbers, the research output, impact and cost effectiveness in Australian universities continue to be dominated by the Institute of Advanced Studies (LAS) and the faculties of the Australian National University (ANU), not by the "sandstone club". For example, ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/376630b0
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