The association of chloroplast DNA with photosynthetic membrane vesicles from spinach chloroplasts

1979 ◽  
Vol 36 (1) ◽  
pp. 169-183
Author(s):  
R.J. Rose
Keyword(s):  
Chloroplast Dna ◽  
Light And Electron Microscopy ◽  
Membrane System ◽  
Chloroplast Division ◽  
Chloroplast Envelope ◽  
Photosynthetic Membrane ◽  
Electron Microscope Autoradiography ◽  
Photosynthetic Membranes ◽  
Spinach Chloroplasts ◽  
Microscope Autoradiography

To investigate the association between chloroplast DNA (cp DNA) and the photosynthetic membranes of spinach chloroplasts, previously suggested by electron-microscope autoradiography, use has been made of vesicles formed by isolating chloroplasts directly in 3.5 mM Mg2+. These chloroplast vesicles consist of photosynthetic membranes, separate from chloroplast envelope membranes. Light and electron microscopy confirm that the vesicles consist of swollen stroma lamellar membranes with some peripheral grana lamellae that are much less swollen. Vesicles labelled with [H]thymidine were obtained from [3H]thymidine-labelled chloroplasts from spinach disks in which chloroplast division and cp DNA synthesis and segregation were occurring. The chloroplast vesicle fraction retains about 45% of the cp DNA as determined by liquid scintillation counting. The cp DNA-membrane associations do not appear to be dependent on the presence of Mg2+. The chloroplast vesicles can be autoradiographed for light microscopy if they are fixed in formaldehyde and no centrifugation steps are used. Light-microscope autoradiography is consistent with a preferential labelling of grana as opposed to stroma membranes, and long lengths of membrane are labelled. It appears that in spinach chloroplasts cp DNA is associated with granal thylakoids at intervals along the length of a continuous photosynthetic membrane system. Such an organization would facilitate cp DNA segregation during chloroplast division.

The localization of (3H) thymidine incorporation in the DNA of replicating spinach chloroplasts by electron-microscope autoradiography

1976 ◽  
Vol 20 (2) ◽  
pp. 341-355
Author(s):  
R.J. Rose ◽  
J.V. Possingham
Keyword(s):  
Grain Size ◽  
Electron Microscope ◽  
Thymidine Incorporation ◽  
Membrane System ◽  
Chloroplast Envelope ◽  
Lamellar System ◽  
Electron Microscope Autoradiography ◽  
Spinach Chloroplasts ◽  
Microscope Autoradiography ◽  
Leaf Disks

Electron-microscope autoradiography has been used to obtain information on the localization of DNA labelled with [3H]thymidine in chloroplasts known to be replicating and concomitantly synthesizing and segregating DNA, in cultured leaf disks. The studies were made using both Microdol-X developer and a ‘compact’ developer which gave a smaller grain size. About 80% of the grains were associated with the granal membranes and with presumptive DNA regions (3-nm fibril material in clear areas). Few grains occurred in association with the chloroplast envelope. We suggest that the DNA of chloroplasts is associated with the grana lamellae and extends into the stroma. Some light-microscope autoradiographs of whole chloroplasts show spiral or helical-like labelling patterns. We interpret these patterns as demonstration of the possibility that DNA occurs along the length of a continuous lamellar membrane system. Chloroplast fractionation experiments provided data consistent with the electron-microscope autoradiographic studies as most of the label was associated with chlorophyll-containing lamellae. We consider an association of chloroplast DNA molecules along the length of a continuous lamellar system would ensure an orderly segregation of DNA to daughter chloroplasts, during the binary fission of spinach chloroplasts by constriction division.

Structural analysis of the photosynthetic membrane from Ectothiorhodospira halochloris

1983 ◽  
Vol 41 ◽  
pp. 740-741
Author(s):  
H. Engelhardt ◽  
R. Guckenberger ◽  
W. Baumeister
Keyword(s):  
Lattice Structure ◽  
Bacterial Species ◽  
Hexagonal Lattice ◽  
Reaction Centre ◽  
Photosynthetic Membrane ◽  
Rhodopseudomonas Viridis ◽  
Photosynthetic Membranes ◽  
Ectothiorhodospira Halochloris ◽  
Main Components

Bacterial photosynthetic membranes contain, apart from lipids and electron transport components, reaction centre (RC) and light harvesting (LH) polypeptides as the main components. The RC-LH complexes in Rhodopseudomonas viridis membranes are known since quite seme time to form a hexagonal lattice structure in vivo; hence this membrane attracted the particular attention of electron microscopists. Contrary to previous claims in the literature we found, however, that 2-D periodically organized photosynthetic membranes are not a unique feature of Rhodopseudomonas viridis. At least five bacterial species, all bacteriophyll b - containing, possess membranes with the RC-LH complexes regularly arrayed. All these membranes appear to have a similar lattice structure and fine-morphology. The lattice spacings of the Ectothiorhodospira haloohloris, Ectothiorhodospira abdelmalekii and Rhodopseudomonas viridis membranes are close to 13 nm, those of Thiocapsa pfennigii and Rhodopseudomonas sulfoviridis are slightly smaller (∼12.5 nm).

Effect of light intensity on the ultrastructure of the filamentous cyanobacterium, Anabaena variabilis

1988 ◽  
Vol 46 ◽  
pp. 300-301
Author(s):  
C. S. Bricker ◽  
S. R. Barnum ◽  
B. Huang ◽  
J. G. Jaworskl
Keyword(s):  
Fatty Acid ◽  
Light Intensity ◽  
Acid Content ◽  
Fatty Acid Content ◽  
Anabaena Variabilis ◽  
Chloroplast Envelope ◽  
Major Constituent ◽  
Filamentous Cyanobacterium ◽  
Photosynthetic Membrane ◽  
Effect Of Light

Cyanobacteria are Gram negative prokaryotes that are capable of oxygenic photosynthesis. Although there are many similarities between eukaryotes and cyanobacteria in electron transfer and phosphorylation during photosynthesis, there are two features of the photosynthetic apparatus in cyanobacteria which distinguishes them from plants. Cyanobacteria contain phycobiliproteins organized in phycobilisomes on the surface of photosynthetic membrane. Another difference is in the organization of the photosynthetic membranes. Instead of stacked thylakolds within a chloroplast envelope membrane, as seen In eukaryotes, IntracytopIasmlc membranes generally are arranged in three to six concentric layers. Environmental factors such as temperature, nutrition and light fluency can significantly affect the physiology and morphology of cells. The effect of light Intensity shifts on the ultrastructure of Internal membrane in Anabaena variabilis grown under controlled environmental conditions was examined. Since a major constituent of cyanobacterial thylakolds are lipids, the fatty acid content also was measured and correlated with uItrastructural changes. The regulation of fatty acid synthesis in cyanobacteria ultimately can be studied if the fatty acid content can be manipulated.

Incorporation of Cholesterol into Peripheral Nerve Myelin

1972 ◽  
Vol 30 ◽  
pp. 334-335
Author(s):  
Frank A. Rawlins
Keyword(s):  
Electron Microscope ◽  
Sciatic Nerve ◽  
Electron Microscope Autoradiography ◽  
Myelin Sheaths ◽  
Microscope Autoradiography ◽  
Grain Distribution ◽  
Sciatic Nerves ◽  
Autoradiographic Analysis ◽  
Old Mice ◽  
Short Times

Several speculations exist as to the site of incorporation of preformed molecules into myelin. The possibility that an autoradiographic analysis of cholesterol-1,2-H3 incorporation at very short times after injection might shed some light in the solution of that problem led to the present experiment.Cholesterol-1,2-H3 was injected intraperitoneally into 24 tenday old mice. The animals were then sacrificed at 10,20,30,40,60,90,120 and 180 min after the injection and the sciatic nerves were processed for electron microscope autoradiography. To analyze the grain distribution in the autoradiograms of cross and longitudinal sections from each sciatic nerve myelin sheaths were subdivided into three compartments named: outer 1/3, middle 1/3 and inner 1/3 compartments.It was found that twenty min. after the injection of cholesterol -1.2-H3 (Figs. 1 and 2), 55% of the total number of grains (t.n.g) found in myelin were within the outer 1/3 compartment, 9% were within the middle 1/3 and 36% within the inner 1/3 compartment

Structure of the chloroplast and its DNA in chloromonadophycean algae

1981 ◽  
Vol 49 (1) ◽  
pp. 401-409
Author(s):  
A.W. Coleman ◽  
P. Heywood
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Membrane ◽  
Nuclear Envelope ◽  
Chloroplast Dna ◽  
Single Layer ◽  
Longitudinal Axis ◽  
Chloroplast Envelope ◽  
Large Numbers ◽  
Gonyostomum Semen ◽  
Chloroplast Stroma

The arrangement and ultrastructure of chloroplasts is described for the Chloromonadophycean algae gonyostomum semen Diesing and Vacuolaria virescens Cienkowsky. The chloroplasts are present in large numbers and are discoid structures approximately 3–4 micrometer in length by 2–3 micrometer in width. In Gonyostomum semen the chloroplasts form a single layer immediately interior to the cell membrane; frequently their longitudinal axis parallels the longitudinal axis of the cell. The chloroplasts in Vacuolaria virescens are more than I layer deep and do not appear to be preferentially oriented. In both organisms, chloroplast bands usually consist of 3 apposed thylakoids, although fusion and interconnections between adjacent bands frequently occur. External to the girdle band (the outermost thylakoids) is the chloroplast envelope. This is bounded by endoplasmic reticulum but there is no immediately apparent continuity between this endoplasmic reticulum and the nuclear envelope. Electron-dense spheres in the chloroplast stroma are thought to be lipid food reserve. Ring-shaped electron-translucent regions in the chloroplast contain chloroplast DNA. The DNA is distributed along this ring in an uneven fashion and, when stained, resembles a string of beads. Each plastid has I ring, and the ring is unbroken in the intact plastid.

scholarly journals Cryo-Electron Tomography Reveals the Comparative Three-Dimensional Architecture of Prochlorococcus, a Globally Important Marine Cyanobacterium

2007 ◽  
Vol 189 (12) ◽  
pp. 4485-4493 ◽  
Author(s):  
Claire S. Ting ◽  
Chyongere Hsieh ◽  
Sesh Sundararaman ◽  
Carmen Mannella ◽  
Michael Marko
Keyword(s):  
Cell Wall ◽  
Electron Tomography ◽  
Three Dimensional ◽  
Membrane System ◽  
Niche Differentiation ◽  
Dimensional Structure ◽  
Comparative Genomic ◽  
Photosynthetic Membrane ◽  
Peptidoglycan Biosynthesis ◽  
Cryo Electron Tomography

ABSTRACT In an age of comparative microbial genomics, knowledge of the near-native architecture of microorganisms is essential for achieving an integrative understanding of physiology and function. We characterized and compared the three-dimensional architecture of the ecologically important cyanobacterium Prochlorococcus in a near-native state using cryo-electron tomography and found that closely related strains have diverged substantially in cellular organization and structure. By visualizing native, hydrated structures within cells, we discovered that the MED4 strain, which possesses one of the smallest genomes (1.66 Mbp) of any known photosynthetic organism, has evolved a comparatively streamlined cellular architecture. This strain possesses a smaller cell volume, an attenuated cell wall, and less extensive intracytoplasmic (photosynthetic) membrane system compared to the more deeply branched MIT9313 strain. Comparative genomic analyses indicate that differences have evolved in key structural genes, including those encoding enzymes involved in cell wall peptidoglycan biosynthesis. Although both strains possess carboxysomes that are polygonal and cluster in the central cytoplasm, the carboxysomes of MED4 are smaller. A streamlined cellular structure could be advantageous to microorganisms thriving in the low-nutrient conditions characteristic of large regions of the open ocean and thus have consequences for ecological niche differentiation. Through cryo-electron tomography we visualized, for the first time, the three-dimensional structure of the extensive network of photosynthetic lamellae within Prochlorococcus and the potential pathways for intracellular and intermembrane movement of molecules. Comparative information on the near-native structure of microorganisms is an important and necessary component of exploring microbial diversity and understanding its consequences for function and ecology.

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