Figure 1

The phenotype of V. carteri : wild-type and transformant. V. carteri consists of ~2000 small, biflagellate, terminally differentiated, somatic cells at the surface and ~16 large reproductive cells in the interior of a spheroid. The reproductive cells develop inside the mother spheroid to embryos and later to juveniles. Up to 99% of the volume of such a spheroid consists of a complex, transparent, glycoprotein-rich extracellular matrix that holds all of the cells in place. (A) Wild-type spheroid of Volvox carteri f. nagariensis short before release of ~16 juvenile spheroids. (B) Spheroid of transformant NitLuc-A172 functionally expressing the G. princeps luciferase gene under control of the V. carteri nitA promoter. Transformant NitLuc-A172 shows the same phenotype as its wild-type parent.