title: The ultrastructure and flexibility of thylakoid membranes in leaves and isolated chloroplasts as revealed by small-angle neutron scattering.
abstract: We studied the periodicity of the multilamellar membrane system of granal chloroplasts in different isolated plant thylakoid membranes, using different suspension media, as well as on different detached leaves and isolated protoplasts-using small-angle neutron scattering. Freshly isolated thylakoid membranes suspended in isotonic or hypertonic media, containing sorbitol supplemented with cations, displayed Bragg peaks typically between 0.019 and 0.023Å(-1), corresponding to spatially and statistically averaged repeat distance values of about 275-330 Å⁻¹. Similar data obtained earlier led us in previous work to propose an origin from the periodicity of stroma thylakoid membranes. However, detached leaves, of eleven different species, infiltrated with or soaked in D2O in dim laboratory light or transpired with D2O prior to measurements, exhibited considerably smaller repeat distances, typically between 210 and 230 Å⁻¹, ruling out a stromal membrane origin. Similar values were obtained on isolated tobacco and spinach protoplasts. When NaCl was used as osmoticum, the Bragg peaks of isolated thylakoid membranes almost coincided with those in the same batch of leaves and the repeat distances were very close to the electron microscopically determined values in the grana. Although neutron scattering and electron microscopy yield somewhat different values, which is not fully understood, we can conclude that small-angle neutron scattering is a suitable technique to study the periodic organization of granal thylakoid membranes in intact leaves under physiological conditions and with a time resolution of minutes or shorter. We also show here, for the first time on leaves, that the periodicity of thylakoid membranes in situ responds dynamically to moderately strong illumination. This article is part of a special issue entitled: photosynthesis research for sustainability: keys to produce clean energy.
authors: Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, Hungarian Academy of Sciences, POB 49, H-1525 Budapest, Hungary.
authors: R
authors: R
authors: Unnep
authors: Institute of Plant Biology, Biological Research Centre, Hungarian Academy of Sciences, POB 521, H-6701 Szeged, Hungary.
authors: O
authors: O
authors: Zsiros
authors: Department of Plant Anatomy, Eötvös University, Pázmány Péter sétány 1/C, H-1117 Budapest, Hungary.
authors: K
authors: K
authors: Solymosi
authors: Institute of Plant Biology, Biological Research Centre, Hungarian Academy of Sciences, POB 521, H-6701 Szeged, Hungary.
authors: L
authors: L
authors: Kovács
authors: Institute of Plant Biology, Biological Research Centre, Hungarian Academy of Sciences, POB 521, H-6701 Szeged, Hungary.
authors: P H
authors: PH
authors: Lambrev
authors: Institute of Plant Biology, Biological Research Centre, Hungarian Academy of Sciences, POB 521, H-6701 Szeged, Hungary.
authors: T
authors: T
authors: Tóth
authors: Institut Laue-Langevin, BP 156, F-38042, Grenoble Cedex 9, France.
authors: R
authors: R
authors: Schweins
authors: IMFUFA, Department of Science, Systems and Models, Roskilde University, DK-4000 Roskilde, Denmark.
authors: D
authors: D
authors: Posselt
authors: Jülich Centre for Neutron Science, Forschungszentrum Jülich GmbH, 85747 Garching, Germany.
authors: N K
authors: NK
authors: Székely
authors: Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, Hungarian Academy of Sciences, POB 49, H-1525 Budapest, Hungary.
authors: L
authors: L
authors: Rosta
authors: Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, Hungarian Academy of Sciences, POB 49, H-1525 Budapest, Hungary; Laboratory for Neutron Scattering, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland.
authors: G
authors: G
authors: Nagy
authors: Institute of Plant Biology, Biological Research Centre, Hungarian Academy of Sciences, POB 521, H-6701 Szeged, Hungary. Electronic address: garab.gyozo@brc.mta.hu.
authors: G
authors: G
authors: Garab
mesh_terms: D000447:Aldehydes; D002021:Buffers; D002473:Cell Wall / Q000648:ultrastructure; D002736:Chloroplasts / Q000648:ultrastructure*; D009502:Neutrons; D018515:Plant Leaves / Q000648:ultrastructure; D053838:Scattering, Small Angle; D020524:Thylakoids / Q000648:ultrastructure*
chemical_list: D000447:Aldehydes; D002021:Buffers; C007860:glutaconaldehyde
keywords: Electron microscopy; Granum; Lamellar repeat distance; Small-angle neutron scattering; Thylakoid membrane