chlorophyll-a and sodium-chlorate

The recent visualization of stomatal nanoparticle uptake ended a 40-yr-old paradigm. Assuming clean, hydrophobic leaf surfaces, the paradigm considered stomatal liquid water transport to be impossible as a result of water surface tension. However, real leaves are not clean, and deposited aerosols may change hydrophobicity and water surface tension. Droplets containing NaCl, NaClO(3), (NH(4))(2) SO(4), glyphosate, an organosilicone surfactant or various combinations thereof were evaporated on stomatous abaxial and astomatous adaxial surfaces of apple (Malus domestica) leaves. The effects on photosynthesis, necrosis and biomass were determined. Observed using an environmental scanning electron microscope, NaCl and NaClO(3) crystals on hydrophobic tomato (Solanum lycopersicum) cuticles underwent several humidity cycles, causing repeated deliquescence and efflorescence of the salts. All physiological parameters were more strongly affected by abaxial than adaxial treatments. Spatial expansion and dendritic crystallization of the salts occurred and cuticular hydrophobicity was decreased more rapidly by NaClO(3) than NaCl. The results confirmed the stomatal uptake of aqueous solutions. Humidity fluctuations promote the spatial expansion of salts into the stomata. The ion-specific effects point to the Hofmeister series: chaotropic ions reduce surface tension, probably contributing to the defoliant action of NaClO(3), whereas the salt spray tolerance of coastal plants is probably linked to the kosmotropic nature of chloride ions.

Topics: Ammonium Sulfate; Biological Transport; Chlorates; Chlorophyll; Fluorescence; Glycine; Glyphosate; Hydrophobic and Hydrophilic Interactions; Malus; Microscopy, Electron, Scanning; Photosynthesis; Photosystem II Protein Complex; Plant Diseases; Plant Leaves; Plant Stomata; Plant Transpiration; Sodium Chloride; Solanum lycopersicum; Solutions; Surface Tension; Water

We studied the interactions of the CO(2)-concentrating mechanism and variable light in the filamentous cyanobacterium Leptolyngbya sp. CPCC 696 acclimated to low light (15 μmol m(-2) s(-1) PPFD) and low inorganic carbon (50 μM Ci). Mass spectrometric and polarographic analysis revealed that mediated CO(2) uptake along with both active Na(+)-independent and Na(+)-dependent HCO(3)(-) transport, likely through Na(+)/HCO(3)(-) symport, were employed to concentrate Ci internally. Combined transport of CO(2) and HCO(3)(-) required about 30 kJ mol(-1) of energy from photosynthetic electron transport to support an intracellular Ci accumulation 550-fold greater than the external Ci. Initially, Leptolyngbya rapidly induced oxygen evolution and Ci transport to reach 40-50% of maximum values by 50 μmol m(-2) s(-1) PPFD. Thereafter, photosynthesis and Ci transport increased gradually to saturation around 1,800 μmol m(-2) s(-1) PPFD. Leptolyngbya showed a low intrinsic susceptibility to photoinhibition of oxygen evolution up to PPFD of 3,000 μmol m(-2) s(-1). Intracellular Ci accumulation showed a lag under low light but then peaked at about 500 μmol photons m(-2) s(-1) and remained high thereafter. Ci influx was accompanied by a simultaneous, light-dependent, outward flux of CO(2) and by internal CO(2)/HCO(3)(-) cycling. The high-affinity and high-capacity CCM of Leptolyngbya responded dynamically to fluctuating PPFD and used excitation energy in excess of the needs of CO(2) fixation by increasing Ci transport, accumulation and Ci cycling. This capacity may allow Leptolyngbya to tolerate periodic exposure to excess high light by consuming electron equivalents and keeping PSII open.

Topics: Acclimatization; Bicarbonates; Biological Transport; Carbon; Carbon Dioxide; Carbon Isotopes; Chlorates; Chlorophyll; Chlorophyll A; Cyanobacteria; DNA, Ribosomal; Light; Photosynthesis; Photosystem II Protein Complex; RNA, Bacterial; RNA, Ribosomal, 16S; Time Factors

The intact Photosystem I core protein, containing the psaA and psaB polypeptides, and electron transfer components P-700 through FX, was isolated from cyanobacterial and higher plant Photosystem I complexes with chaotropic agents followed by sucrose density ultracentrifugation. The concentrations of NaClO4, NaSCN, NaI, NaBr or urea required for the functional removal of the 8.9 kDa, FA/FB polypeptide was shown to be inversely related to the strength of the chaotrope. The Photosystem I core protein, which was purified to homogeniety, contains 4 mol of acid-labile sulfide and has the following properties: (i) the FX-containing core consists of the 82 and 83 kDa reaction center polypeptides but is totally devoid of the low-molecular-mass polypeptides; (ii) methyl viologen and other bipyridilium dyes have the ability to accept electrons directly from FX; (iii) the difference spectrum of FX from 400 to 900 nm is characteristic of an iron-sulfur cluster; (iv) the midpoint potential of FX, determined optically at room temperature, is 60 mV more positive than in the control; (v) there is indication by ESR spectroscopy of low-temperature heterogeneity within FX; and (vi) the heterogeneity is seen by optical spectroscopy as inefficiency in low-temperature electron flow to FX. The constraints imposed by the amount of non-heme iron and labile sulfide in the Photosystem I core protein, the cysteine content of the psaA and psaB polypeptides, and the stoichiometry of high-molecular-mass polypeptides, cause us to re-examine the possibility that FX is a [4Fe-4S] rather than a [2Fe-2S] cluster ligated by homologous cysteine residues on the psaA and psaB heterodimer.

Topics: Bromides; Centrifugation, Density Gradient; Chlorates; Chlorophyll; Cold Temperature; Cross-Linking Reagents; Cyanobacteria; Digitonin; Electron Spin Resonance Spectroscopy; Electron Transport; Glutaral; Kinetics; Light-Harvesting Protein Complexes; Molecular Weight; Octoxynol; Oxidation-Reduction; Photochemistry; Photosynthetic Reaction Center Complex Proteins; Photosystem I Protein Complex; Plant Proteins; Polyethylene Glycols; Sodium; Sodium Compounds; Sodium Iodide; Spectrophotometry; Thiocyanates; Urea