scholarly journals The Alga Ochromonas danica Produces Bromosulfolipids

2016 ◽  
Vol 18 (5) ◽  
pp. 1124-1127 ◽  
Author(s):  
Alexander R. White ◽  
Brendan M. Duggan ◽  
Shiou-Chuan Tsai ◽  
Christopher D. Vanderwal
Keyword(s):  
Ochromonas Danica

The effects of spectinomycin and ethidium bromide on the synthesis of organelle rRNA and on ultrastructure in Ochromonas danica

1980 ◽  
Vol 43 (1) ◽  
pp. 119-136
Author(s):  
H. Smith-Johannsen ◽  
D. Fromson ◽  
S.P. Gibbs
Keyword(s):  
Electron Microscopy ◽  
Ethidium Bromide ◽  
Ribosomal Proteins ◽  
Specific Inhibitor ◽  
Chloroplast Ultrastructure ◽  
Normal Amount ◽  
Chloroplast Membranes ◽  
Mitochondrial Ribosomes ◽  
Mitochondrial Rrna ◽  
Ochromonas Danica

The effects of 24-h exposure to spectinomycin (100 microgram/ml) and ethidium bromide (1 microgram/ml) on the accumulation of chloroplast and mitochondrial rRNAs and on organelle ultrastructure were studied in greening cells of Ochromonas danica. Cells treated with ethidium bromide for 24 h divide at the same rate as controls but contain less than one third the normal amount of mitochondrial rRNA. Ultrastructural observations showed that these cells contain only 10% the number of mitochondrial ribosomes found in controls as well as fewer mitochondrial cristae. Ethidium bromide has no effect on chloroplast ultrastructure in Ochromonas. Greening cells treated with spectinomycin grow at close to control rates but contain 30–40% less chloroplast rRNA than do controls. Electron microscopy showed that spectinomycin disrupts the organization of chloroplast membranes and reduces the number of chloroplast ribosomes by 30%. Under these conditions, spectinomycin has no effect on mitochondrial rRNA or ultrastructure. Since spectinomycin is a specific inhibitor of translation on 70S ribosomes, these results are consistent with the possibility that at least some chloroplast ribosomal proteins are synthesized in the chloroplast of Ochromonas.

The route of entry of cytoplasmically synthesized proteins into chloroplasts of algae possessing chloroplast ER

1979 ◽  
Vol 35 (1) ◽  
pp. 253-266
Author(s):  
S.P. Gibbs
Keyword(s):  
Protein Synthesis ◽  
Nuclear Envelope ◽  
Outer Membrane ◽  
Chloroplast Envelope ◽  
Inhibit Protein Synthesis ◽  
Ochromonas Danica ◽  
Plastid Proteins ◽  
Regular Network ◽  
Cytoplasmic Ribosomes ◽  
Plastid Ribosomes

In 8 classes of algae, namely the Cryptophyceae, Raphidophyceae, Haptophyceae, Chrysophyceae, Bacillariophyceae, Xanthophyceae, Eustigmatophyceae and Phaeophyceae, the chloroplasts, in addition to being surrounded by a double-membraned chloroplast envelope, are also enclosed by a cisterna of endoplasmic reticulum called the chloroplast ER. Often this ER cisterna is continuous with the outher membrane of the nuclear envelope in such a manner that the nuclear envelope forms a part of the ER sac enclosing the chloroplast. In all these classes of algae except the Cryptophyceae, a regular network of tubules and vesicles, named the periplastidal reticulum, is present at a specific location between the chloroplast envelope and the chloroplast ER. In the Cryptophyceae, scattered vesicles are found between the chloroplast envelope and the chloroplast ER. Ribosomes which have been shown to be arranged to polysomes are found on the outer membrane of the chloroplast ER. It is proposed that nuclear-coded proteins which are destined for the chloroplast are synthesized on these polysomes, passing during synthesis into the lumen of the ER cisterna. Vesicles containing these proteins then pinch off the chloroplast ER and form the periplastidal reticulum. Vesicles containing these proteins then pinch off the chloroplast ER and form the periplastidal reticulum. Vesicles then fuse with the outer membrane of the chloroplast envelope thereby delivering their contents to the lumen of the chloroplast envelope. Proteins then cross the inner membrane of the chloroplast envelope in an as yet unknown manner. Experimental evidence for this hypothesis comes from studies on Ochromonas danica using chloramphenicol and spectinomycin, which inhibit protein synthesis on plastid ribosomes, and cycloheximide, which inhibits protein synthesis on cytoplasmic ribosomes. In cells of Ochromonas exposed to chloramphenicol or spectinomycin, the periplastidal reticulum proliferates markedly becoming several layers thick. Presumably this build up of periplastidal reticulum occurs because the transport of cytoplasmically synthesized plastid proteins is slowed down when protein synthesis in the chloroplast is inhibited. Conversely, when cells of Ochromonas are treated with cycloheximide, there is a reduction in the amount of periplastidal reticulum presumably because there are no cytoplasmically synthesized proteins to be transported into the chloroplast.

Characterization of rRNAs from the chrysophyte alga Ochromonas danica

1979 ◽  
Vol 14 (1) ◽  
pp. 91-101
Author(s):  
Heidi Smith-Johannsen ◽  
Sarah P. Gibbs ◽  
David Fromson
Keyword(s):  
Ochromonas Danica

Intracellular Localization of Two Betaine Lipids by Cell Fractionation and Immunomicroscopy

1997 ◽  
Vol 52 (7-8) ◽  
pp. 487-495 ◽  
Author(s):  
K. Department of Chemistry and Biochem ◽  
W. Department of Chemistry and Biochem ◽  
A. Faculty of Biology, University of B
Keyword(s):  
Fluorescence Microscopy ◽  
Cellular Localization ◽  
Gradient Centrifugation ◽  
Intracellular Localization ◽  
Rabbit Serum ◽  
Cell Fractionation ◽  
Thin Sections ◽  
Ochromonas Danica ◽  
Betaine Lipids ◽  
Cyt C

Abstract The cellular localization of the betaine lipids diacylglyceryl-N,N,N-trimethylhomoserine (DGTS) and diacylglycerylhydroxymethyl-N,N,N-trimethyl-β-alanine (DGTA) was investi­ gated by a) chemical analysis of subcellular fractions and b) immunochemical methods using specific antisera and either fluorescence microscopy or electron microscopy for detection of the label. A homogenate of Lycopodium annotinum (Pteridophyta) was fractionated by differential and density gradient centrifugation. The particulate fractions obtained were analyzed for chlorophyll, cyt c oxidase, NADH-cyt c reductase and DGTS. Non-plastidial fractions were enriched in DGTS and only minor amounts of this lipid could be attributed to chloroplasts. Anti-DGTS and anti-DGTA sera were produced by immunization of rabbits. The monospecificity of the antisera was examined with cells of Chlamydomonas reinhardtii (Chlorophyceae) containing DGTS, Pavlova lutheri (Haptophyceae) containing DGTA and Ochromonas danica (Chrysophyceae) containing both DGTS and DGTA. Euglena gracilis which is free of betaine lipids, was used as a control. For the test, a FITC-coupled goat anti-rabbit antibody was used and detected by fluorescence microscopy. Thin sections of Ochromonas and Pavlova were incubated first with the anti-lipid sera and subsequently with a gold-coupled anti-rabbit serum and then examined in the electron microscope. With O chro­ monas, anti-DGTS as well as anti-DGTA sera gave an accumulation of gold label in the cytoplasmic space but not in the chloroplasts. Similar results were obtained with Pavlova using anti-DGTA serum. These results describe for the first time the cytochemical localiza­ tion of DGTS and DGTA strongly suggesting both these lipids to be associated mainly with non-plastidial structures.

scholarly journals Halogenation-Dependent Effects of the Chlorosulfolipids of Ochromonas danica on Lipid Bilayers

2020 ◽  
Vol 15 (11) ◽  
pp. 2986-2995
Author(s):  
Frank R. Moss III ◽  
Gabrielle E. Cabrera ◽  
Grace M. McKenna ◽  
Giulio J. Salerno ◽  
Steven R. Shuken ◽  
...  
Keyword(s):  
Lipid Bilayers ◽  
Ochromonas Danica
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