Fig. 1. Histogram showing the ratio and distribution of phenotypes among V. carteri 153-68 transformed with WT (A1), mutant ATG (ATG1-ATG7) and mutant ORF2 (ATG2Stop) regA DNA, respectively, and the observed phenotypes. (A) A histogram indicating the abundance - relative to the WT control, A1 (100%) - of co-transformants exhibiting three different phenotypes: wild-type (WT), somatic regenerator (Reg) and modified somatic regenerator (M-Reg). (B) An adult WT Volvox carteri spheroid containing terminally differentiated somatic cells on the surface and 16 reproductive cells (gonidia) inside the spheroid [picture from Schmitt (Schmitt, 2003)]. (C) The Reg mutant phenotype is characterized by somatic cells that dedifferentiate, grow and redifferentiate to become fully functional gonidia (Kirk et al., 1999). (D) An adult M-Reg spheroid with juveniles ready for hatching. Just a few somatic cells have begun to grow and to redifferentiate, suggesting suboptimal expression of the regA gene.