Genetic Basis of Specificity in Dinoflagellate-Invertebrate Symbiosis

摘要

The prime goals of this award were: (1) to study the composition of the cellwalls of symbiotic dinoflagellates, (2) analyze the chemical composition of the glycoproteins exuded by symbiotic dinoflagellates and (3) sequence the SSU rRNA gene from the symbiotic dinoflagellate Symbiodinium pilosum and assess its phylogenetic position relative to other protists. All three of these goals have been accomplished, and manuscripts or published papers describing the observations are attached. Briefly, the cell walls of symbiotic dino-flagellates are composed of cellulose and proteins, but whether any of the proteins are involved in recognition of symbionts by hosts remains unresolved. The large molecular weight glycoproteins exuded by symbiotic dinoflagellates have been characterized, and polyclonal antibodies have been prepared against them. We have preliminary evidence that show that the glycoproteins excuded by the symbionts in culture are also exuded in hospite. Analyses of the SSU rRNA sequence of S. pilosum shows that it is clustered among the dinoflagellates which appear to share a common ancestry with the Apicomplexa and the Ciliata.