Free-living nematodes Caenorhabditis elegans possess in their mitochondria an additional rhodoquinone, an essential component of the eukaryotic fumarate reductase system.
The respiratory chain of Caenorhabditis elegans was characterized in mitochondria isolated from aerobically grown nematodes. Nematode mitochondria contain ubiquinone-9 as a major component and rhodoquinone-9 as a minor component. The ratio of ubiquinone-9/rhodoquinone-9 is higher in C. elegans mitochondria than in mitochondria from second-stage larvae of Ascaris suum, the free-living stage of porcine gut-dwelling nematode. The individual oxidoreductase activities comprising succinate oxidase and the amount of substrate-reducible cytochromes are comparable to those of mitochondria from second-stage larvae of A. suum. The specific activity of fumarate reductase is lower in C. elegans mitochondria than in mitochondria from second-stage larvae of A. suum, but still higher than in mammalian mitochondria. These results indicate that the free-living nematode C. elegans is capable of synthesizing rhodoquinone, as distinguished from aerobic mammalian species, although its mitochondria appear more aerobic than A. suum larval mitochondria.
Takamiya
S
S
Department of Parasitology, Division of Biochemical Analyses, Central Laboratory of Medical Sciences, Juntendo University School of Medicine, Hongo 2-1-1, Bunkyo-ku, Tokyo, 113-8421, Japan. stakamiy@med.juntendo.ac.jp
Matsui
T
T
Taka
H
H
Murayama
K
K
Matsuda
M
M
Aoki
T
T
D000332:Aerobiosis; D000818:Animals; D017173:Caenorhabditis elegans / Q000502:physiology*; D004579:Electron Transport; D008928:Mitochondria / Q000378:metabolism*; D013053:Spectrophotometry; D013385:Succinate Dehydrogenase / Q000378:metabolism*; D014451:Ubiquinone / Q000031:analogs & derivatives* / Q000378:metabolism
D014451:Ubiquinone; D013385:Succinate Dehydrogenase; C003304:rhodoquinone