Origin of bistramide a identified in Lissoclinum bistratum (Urochordata): possible involvement of symbiotic Prochlorophyta

An attempt was made to determine whether bistramide A (=bistratene A), a polycycloether with biological activity isolated from Lissodinum bistratum Sluiter, originates from the ascidian itself or from its symbiont Prochlorophyta. A high-pressure liquid chromatography assay carried out on the whole ascidian, the ascidian without a portion of its Prochloron and the Prochloron themselves gave concentrations respectively of 0.182,0.166 and 0.850%. In view of these results, as well as of the capacity of Prochloron to synthesize complex nitrogenous products and the cytotoxicity of these products, it is hypothesized that bistramide A originates exclusively in Prochloron.