1. Algal Evolution Johanna Weston Keeling, 2004

2. 3.5 billion cyanobacteria 2.2 to 1.5 billion mitochondial origin 1.5 – 1.2 Plastid “Little Green Slaves” (Dyall et al., 2004)

3. ENDOSYMBIOSIS – Primary – Secondary – Tertiary – Serial Secondary (Keeling, 2004)

4. How do endosymbionts become organelles? Organelle – discrete subcellular structure of specialized function usually bound by two or more membranes Metabolite antiporters and Biochemical pathways Genetic integration and reduction Protein import apparatus

5. Phosphate Translocator Family Antiport dependent on counter-exchange Algae profit from cyanobacteria carbon fixation ER/Golgi metabolite translocator protein in host recruited to the plastid envelope (Bhattacharya et al., 2007)

6. Transfer and Reduction Cyanobacteria – 2000 to 4000 kb Plastids – < 200 kb – < 200 genes “Muller’s ratchet” Oxygen free radials (Bhattacharya et al., 2007)

7. TIC - TOC Defining feature of organelle genesis Sophisticated outcome of the requirement for regulated protein import Evolutionary diverse origins – Cyanobacteria – Co-option of host genes – HGT from bacteria Transit peptideN C (Gould et al., 2008)

8. TIC-TOC Independent Existing endomembrane system of host cell Paulinella chromatophora α – carbonic anhydrase **2 o Endosymbiosis combination of both (Gould et al., 2008)(Bhattacharya et al., 2007)

9. Animal-Algal Endosymbiosis Elysia chlorotica and chloroplasts of Vaucheria litorea 9 months with only light and CO 2 Not inherited (Mujer et al., 1996) (Green et al., 2000)

10. References Bhattacharya, Debashish, et al. "How do endosymbionts become organelles? Understanding early events in plastid evolution." BioEssay (2007): 1239-1246. Gould, Sven, Ross Waller and Geoffrey Macfadden. "Plastid evolution." Annual Review of Plant Biology (2008): 491-517. Graham, Linda E., James M. Graham and Lee W. Wilcox. Algae. 2. San Francisco: Benjamin Cummings, 2009. Green, Brian, et al. "Mullusc-algal chloroplast endosymbiosis. Photosynthesis, thylakoid protein maintenance, and chloroplast gene expression continue for many months in the absence of the algal nucleus." Plant Physiology (2000): 331-342. Keeling, Patrick. "Diversity and evolutionary history of plastids and their hosts." Americal Journal of Botany (2004): 1418-1493. Mujer, Cesar, et al. "Chloroplast genes are expressed during intracellular symbiotic association of Vaucheria litorea plastids with the sea slug Elysia chlorotica." Cell Biology (1996): 12333-12338. Weber, Andreas, Marc Linka and Debashish Bhattacharya. "Single, ancient orgin of a plastid metabolite translocator family in Plantae from an endomembrane-derived ancestor." Eukaryotic Cell (2006): 609-612.