Immunolocalization and distribution of form ii rubisco in the pyrenoid and chloroplast stroma of amphidinium carterae and form i rubisco in the symbiont-derived plastids of peridinium foliaceum (dinophyceae)
Article first published online: 25 DEC 2001
Journal of Phycology
Volume 36, Issue 1, pages 127–138, February 2000
How to Cite
Jenks, A. and Gibbs, S. P. (2000), Immunolocalization and distribution of form ii rubisco in the pyrenoid and chloroplast stroma of amphidinium carterae and form i rubisco in the symbiont-derived plastids of peridinium foliaceum (dinophyceae). Journal of Phycology, 36: 127–138. doi: 10.1046/j.1529-8817.2000.99114.x
- Issue published online: 25 DEC 2001
- Article first published online: 25 DEC 2001
- 1 Received 13 June 1999. Accepted 12 October 1999.
- Amphidinium carterae ;
- CO2–concentrating mechanism;
- Peridinium foliaceum;
- Phaeodactylum tricornutum;
- Rubisco Form II
Chloroplasts of peridinin-containing dinoflagellates have recently been shown to contain Form II Rubisco, which consists of large subunits only and is coded by nuclear genes. We have used immunoelectron microscopy to determine the distribution of Form II and Form I Rubisco in dinoflagellates. In sections of Amphidinium carterae Hulburt, the pyrenoid was intensely labeled and the rest of the chloroplast moderately labeled by antisera to Form II Rubisco from the purple non-sulfur bacterium Rhodospirillum rubrum and the symbiotic dinoflagellate Symbiodinium sp. No labeling was observed when sections were exposed to antiserum against Form I Rubisco of the haptophyte alga Isochrysis galbana. In contrast, cell sections of the dinoflagellate Peridinium foliaceum (Stein) Biecheler, whose chloroplasts belong to a diatom endosymbiont, showed no labeling with the two antisera against Form II Rubisco, but heavy pyrenoid labeling was present after treatment with antiserum against Form I Rubisco of I. galbana. The same immunolabeling results were obtained with the free-living diatom Phaeodactylum tricornutum Bohlin. Volumetric analysis of the distribution of Form II Rubisco in the chloroplast of A. carterae showed that, in cells grown under moderate photon irradiance, 72.9% of the plastid's Rubisco was localized in the pyrenoid, whereas in cells grown under low irradiance only 37.0% of the Rubisco was found in the pyrenoid. This light-induced concentration of Rubisco in the pyrenoid suggests that a CO2–concentrating mechanism may elevate CO2 within the pyrenoid, favoring the efficient fixation of CO2 by pyrenoid Rubisco.