1. Distribution of the two photosystems (PS I and PS II) in the thylakoid membranes of the alga Euglena gracilis. The distribution of photosystem I and II (PS I and PS II) in the alga Euglena gracilis Z strain was studied by electron microscopic immunocytochemistry. In this alga, the thylakoids are not organized in gram structures, as they are in higher plants. Two different antibodies were used to identify PS I. One is directed against particles of PS I from maize and the other against the 60 and 62 kDa PS I reaction centre proteins of the cyanobacterium Synechococcus elongatus. Both antibodies demonstrated the presence of PS I in the two types of thylakoid membranes, appressed (AM) and non-appressed (NAM). Quantitative analysis showed that 60--74% of PS I is in the AM and 26--40% is in the NAM, and since about 80--90% of the membranes are AM, that PS I is more concentrated in the NAM. An antibody directed against the CP47 protein of PS II also revealed labelling in both types of thylakoid membranes (54% in AM and 46% in NAM). PS II is again more concentrated in the NAM. I demonstrated by the photo-oxidation of 3,3'-diaminobenzidine that there is PS I activity in the two types of membranes and, moreover, that there are changes in this activity during the light cycle of the cell. My results indicate that the distribution of PS I and PS II in Euglena gracilis Z strain is different from that of higher plants and is similar to that seen in green algae. The possible evolutionary significance of our observations are discussed. / 2. Localization of the protein CP47 (plastid protein) in the mitochondria of euglenoids. The localization of the CP47 protein to the mitochondria of euglenoids was studied by electron microscopic immunocytochemistry. My results demonstrate that this protein, which is coded by chloroplast DNA in all algae and plants, is present in whole or in part in the mitochondria of Euglena gracilis and related euglenoids. I used two different antibodies against the protein CP47 (anti-CP47 from Chlamydomonas reinhardtii and S. elongatus) to test wild-type, light-grown, cells of Euglena. Both antibodies selectively labelled the mitochondria. These results furthermore suggest that this labelling is particularly associated with mitochondrial cristae. Anti-CP47 from S. elongatus also labelled the mitochondria of other euglenoids, such as dark-grown cells of Euglena gracilis, the mutant Y9Z1NaL, and Astasia longa. Since the CP47 protein is present in dark-grown cells and in the mutant Y9Z1NaL, which are organisms that do not have an active psbB gene, I suggest that a gene transfer has occurred from the plastid to the mitochondria during evolution. Because our results show the presence of CP47 in the mitochondria of Astasia longa, I postulate that the transfer occurred before the branching of Astasia from Euglena.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.36755 |
| Date | January 2000 |
| Creators | Bonavia-Fisher, Bruna. |
| Contributors | Gibbs, S. P. (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Department of Biology.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001782990, proquestno: NQ69855, Theses scanned by UMI/ProQuest. |
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