Nutrient availability regulates Xenopus laevis tadpole growth and progression through developmental stages. Nutrient availability regulates Xenopus laevis tadpole growth and progression through developmental stages. (A) Schematic of experimental timeline. Day 0 is defined as stage 46. Some animals were euthanized at day 0 and the rest were separated into three nutritional treatment groups: fed=continuously fed twice a day for 10 days (green, top); NR=nutrient restricted for 10 days (blue, middle); and DF=nutrient restricted to day 3 and then fed twice a day for 7 days (orange, bottom). Empty boxes indicate no additional feeding; striped boxes indicate supplemental food. Colors in A correspond to images in C and data in D and E. (B) Depiction of early and late stage 47 animals. (C) Representative images of tadpoles from each group from three time points, ventral side visible. Scale bar, 5 mm. (D) Plot of normalized body length in tadpoles from the three different nutritional groups defined in A: fed (green triangles), NR (blue squares) and DF (orange circles). NR led to significantly shorter body lengths starting on Day 4. DF reversed the increase in body length starting on day 5. (E) Plot of Nieuwkoop–Faber stage in the three different nutritional treatment groups defined in A. NR slowed average progression of development, and DF significantly increased progression of development by day 6. Refer to Table 1 for data and Table 2 for corresponding statistics; n=500 animals total from two independent clutches, with a subset of 11–22 animals measured per group per time point. C. R. McKeown et al. J Exp Biol 2017;220:358-368 © 2017. Published by The Company of Biologists Ltd