Paramylon synthesis by Euglena gracilis photoheterotrophically grown under low O2 pressure |
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Authors: | R Calvayrac D Laval-Martin J Briand J Farineau |
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Institution: | (1) Laboratoire des Membranes Biologiques, Université de Paris VII, Tour 54-53, 3è étage, 2, place Jussieu, F-75005 Paris;(2) Service de Biophysique du Département de Biologie-Commissariat à l'Energie Atomique, C.E.N. Saclay, B.P. 2, F-91190 Gif-sur-Yvette, France |
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Abstract: | Special culture conditions for Euglena gracilis Z and ZR are described. They induce interactions between the chloroplast and mitochondrial metabolisms leading to paramylon synthesis. When grown in continuous light under pure nitrogen and in the presence of lactate as the sole carbon source, sugar synthesis occurs during the first 24 h of culture with the participation of both mitochondria (using lactate) and of chloroplasts (fixing CO2 from lactate decarboxylation). The activities of ribulose bisphosphate carboxylase, phosphoenolpyruvate carboxylase, and phosphoenolpyruvate carboxykinase are very high and mitochondria and chloroplasts develop then a common network of vesicles in which paramylon grains can be seen. Electron micrographs demonstrate membrane continuity between the two types of organelles. Occasionally the mitochondrial matrix and the chloroplast stroma are separated by only a unit membrane.Abbreviations Chl
chlorophyll
- OAA
oxaloacetic acid
- PEP
phosphoenolpyruvate
- RuBP
ribulose bisphosphate
- DTT
1,4-dithiothreitol
- PVP
polyvinylpyrrolidone |
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Keywords: | Aerophily (micro-) Chloroplasts Euglena Mitochondria Paramylon synthesis |
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