Localization of RubisCO and sulfur in endosymbiotic bacteria of the gutless marine oligochaete Inanidrilus leukodermatus (Annelida)
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- Krieger, J., Giere, O. & Dubilier, N. Marine Biology (2000) 137: 239. doi:10.1007/s002270000355
The chemoautotrophic potential of the two co-occurring larger and smaller bacterial endosymbionts of the gutless marine oligochaete Inanidrilus leukodermatus was determined using immunocytochemistry. An antibody directed against the Form I of ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO), the key CO2-fixing enzyme of the Calvin–Benson cycle, consistently labeled the larger symbionts. Electron microscopic spectroscopy showed that the larger symbionts contained sulfur in intracellular globules and to a lesser degree in the cytoplasm. The presence of RubisCO and sulfur indicates that the larger endosymbionts of I. leukodermatus are chemoautotrophic sulfur-oxidizing bacteria. In contrast, no RubisCO or sulfur was detected in the smaller endosymbionts of this host.