PARENT SESSION
Posters P1D Photosynthesis and global change. Abstracts (699-710)

Isolation of intact algal symbiosomes from the zooanthid, Zooxanthus robustus. Rosanne Quinnell^*,1, Mauricio Rodriguez-Lanetty², Carol Scaramuzzi¹, Aniuska Kazandjian¹, Anthony Larkum¹, ¹ School of Biological Sciences, NSW, Australia² Oregon State University, USA

ABSTRACT- Symbiosome membranes separate endosymbiont from host tissue and are usually derived from host tissue. In zoanthid, Zoanthus robustus, the symbiosome formed during endosymbiosis, is comprised of zooxanthellae, surrounded by and separated from the host endodermal cells by the symbiosome membrane. The symbiosome membrane therefore forms an interface between the host endodermal cell cytoplasm and the endosymbiotic alga, and presumably plays a pivotal role in communication between host and endosymbiont, and it is likely to be involved in the release of the endosymbiont en masse (mass coral bleaching) during periods of global warming and the subsequent rise in sea water temperature, as well as on a smaller scale during conditions of overcrowding within the host cell where expulsion is a means of controlling endosymbiont population. Marine algal symbioses play a vital role in maintaining the integrity of the Great Barrier Reef and so the symbiosome membrane and associated proteins are of interest. We have isolated intact symbiosomes using as series of mechanical disruptions coupled to differential sucrose gradient centrifugation in the presence of protease inhibitors and seawater. We are currently working to improve the purity of the isolated symbiosome membranes, and initial membrane preparations revealed a number of putative symbiosome proteins (17.5, 49, 70 and 80 kDa); characterisation of these proteins could provide vital information as to the molecular processes involved in coral bleaching.

KEY WORDS: marine algae, symbiosomes, coral bleaching