Neural control of body-plan axis in regenerating planaria
Fig 7
Model-predicted morphogen gradients are consistent with experimentally-observed regeneration outcomes for a variety of cutting scenarios of 2H worms, supporting the vector transport hypothesis.
Planaria heteromophoses show organism-level polarities consistent with head number. In 1H worms (A), cilia flow vector fields (B) occur as monopolar gradients with flow directed away from the single head (B, C). In 2H worms (D) bipolar cilia flow fields were observed (E), which exhibit coordinated beat movement away from each of the two heads (F). From the bipolar cilia beat in 2H worms, we hypothesize a bipolar nervous system, where example synapsin stains of a whole 2H worm (F, G) and nerve polarity map trace (H) are shown. The white dotted line shows location of proposed line of symmetry at the midpoint between the two pharnyx for the bipolar 2H transport gradient (H), which is consistent with the observed location of cilia beat flow pattern symmetry in 2H worms. Panels I, J, K, L, M, and N show model-predicted steady-state ERK concentrations, where higher ERK levels are probabilistically associated with head outcomes (as shown in O). Cutting 2H worms showed experimental regeneration outcomes consistent with model predictions for a variety of cutting scenarios (I, J, K, L, M, N). A Chi2 test was used to compare model and experimental frequencies which showed corroboration between experiment and the model with p < 0.05.