Fig. 5: Generation of Elav⁺ peptidergic neurons subtypes from FoxL2⁺/SoxC⁺ progenitors.

A Lineage tracing of peptidergic neurons from continuously labeled FoxL2 > KikGR⁺ Piwi1⁺ progenitors. These progenitors give rise to orange and red FoxL2 > KikGR⁺ peptidergic neurons at 2, 4, and 7 days post-photoconversion. Transiently expressing SoxC > KikGR⁺ progenitors generate peptidergic neurons with green, orange, and red reporter states present at 2, 4, and 7 days photoconversion, reflecting predicted differences between continuous (FoxL2 > KikGR) and transient (SoxC > KikGR) driver expression in the peptidergic lineage. Data shown in (B, C). B and C Proportion of green, orange and red Elav⁺ peptidergic neurons (Neural 1 class) recovered from FoxL2 > KikGR⁺ and SoxC > KikGR⁺ cells at 2, 4, and 7 days photoconversion. D Peptidergic neuron development: (top, scenario 1) neuron clusters encompass both differentiation intermediates and end states or (bottom, scenario 2) neuron clusters are distinct terminally differentiated subtypes generated in parallel. SoxC > KikGR labels early intermediate states (green or orange cells, no red cells), and late differentiated states accumulate red cells (scenario 1, see Supplementary Fig. 14). The ratio of green + orange to red cells across cell clusters distinguishes between intermediates or concurrent differentiated states within a cellular lineage. Letters indicate distinct neuron clusters. E Distribution of SoxC > KikGR⁺ peptidergic neuron clusters at 7 days post-photoconversion shows similar green + orange to red cells proportions across clusters, supporting that they are terminally differentiated neurons (scenario 2 in D) without intermediates among these. Additional data in Supplementary Fig. 14. F Proportional abundance of SoxC > KikGR⁺ and FoxL2 > KikGR⁺ peptidergic neural subtypes (in blue, R² = 0.66). For comparison, digestive secretory cells are shown in orange and differentiated cell types that do not fit either proportional relationship within dashed lines. Additional data in Supplementary Fig. 14E. E, F 95% confidence interval of the fitted linear regression is shown in shaded gray. G Model of peptidergic neuron development: peptidergic-committed Piwi1⁺ multipotent cells differentiate into distinct peptidergic subtypes within 4 days in adults. Data provided in Source Data File 5.