Symbiotic interactions are common and important in a wide variety of plant and animal communities. Among the more complex symbioses is the mutualism between benthic marine invertebrates, especially cnidarians, and photosynthetic dinoflagellate algae (zooxanthellae). This type of symbiosis has had a key role in the formation of an important marine ecosystem, the coral reef. Little is known about the molecular basis for the establishment and maintenance of these common biological relationships. The symbiosis between scleractinian corals and their zooxanthellae is highly susceptible to changes in environmental factors such as elevated seawater temperature and/or elevated light levels. Global warming has impacted coral reefs world wide by causing the disruption of these symbioses (coral bleaching), causing many corals to subsequently die. It is now urgent to gain a better understanding of the molecular and cellular interactions that are critical to the functional integrity of these symbioses. The PIs have assembled a team of coral reef biologists (Coffroth, Szmant) with a long record of field experience in studying symbiotic relationships in marine ecosystems, genome scientists (Medina, Manohar, Nelson, Terry) with wide-ranging expertise in high throughput genomic techniques and analysis of data generated by such methods, and educational experts (Tang) with high impact capabilities for public outreach through the educational programs in a museum/aquarium setting. The PIs have several members on the team who are part of minority groups, including six women (Coffroth, Manohar, Medina, Szmant, Tang, and Terry), two Hispanic (Medina, Szmant), and two Asian-Americans (Manohar, Tang). The PIs are using microarray expression profiling developed from expressed sequence tags (EST) data to identify genes and cellular pathways involved in the host-zooxanthellae symbiosis in the Montastraea faveolata mutualistic system from Caribbean tropical reef areas. They are performing gene manipulation experiments to establish function of these genes. When accompanied by sequencing of bacterial artificial chromosome (BAC) clones containing them, this approach will contribute to understanding how these genes are regulated in both the host and the symbiont. The research is the first attempt to look at a very important mutualistic relationship using a genome wide analysis of gene expression. The PIs are making all the resources generated by this project (ESTs, microarrays, cDNA and BAC libraries) available through several outreach programs. Gaining a better understanding of host-symbiont relationships in coral reef ecosystems can have implications for atmospheric and ocean sciences, conservation biology and the study and diagnosis of microbial diseases in corals. Consequently, this project will be of great interest to a broader scientific community.