Coupling of growth rate and developmental tempo reduces body size heterogeneity in C. elegans

Animals must reach the correct size during development, despite stochastic differences in their growth rate. Here, Stojanovski et al. show that a coupling of growth and development by an oscillatory timer buffers fluctuations in the growth of the nematode C. elegans to ensure its correct size. Animals increase by orders of magnitude in volume during development. Therefore, small variations in growth rates among individuals could amplify to a large heterogeneity in size. By live imaging of C. elegans, we show that amplification of size heterogeneity is prevented by an inverse coupling of the volume growth rate to the duration of larval stages and does not involve strict size thresholds for larval moulting. We perturb this coupling by changing the developmental tempo through manipulation of a transcriptional oscillator that controls the duration of larval development. As predicted by a mathematical model, this perturbation alters the body volume. Model analysis shows that an inverse relation between the period length and the growth rate is an intrinsic property of genetic oscillators and can occur independently of additional complex regulation. This property of genetic oscillators suggests a parsimonious mechanism that counteracts the amplification of size differences among individuals during development.

Automated summary

Animals need to reach the correct size during development, but stochastic differences in growth rate can lead to variations in size. This study shows that the nematode C. elegans uses an oscillatory timer to couple growth and development, buffering fluctuations in growth to ensure the correct size.