Nyaanga, Joy, Andersen, Erik, Goss, Christina, Mangan, Niall, Shirman, Sasha, Zhang, Gaotian
[
International Worm Meeting,
2021]
Organismal growth is regulated on a genetic level, as changes in gene expression patterns and signaling dictate much of development. However, environmental conditions (e.g. nutrients and temperature) also have strong impacts on growth. For a comprehensive understanding of organismal growth, the links among genetics, environment, and metabolic regulation must be considered. Studies of single cells have revealed that growth regulation can be achieved using time or size sensing control methods. In multicellular organisms, regulatory mechanisms must not only control single cell growth but also integrate it across organs and tissues during development. The nematode Caenorhabditis elegans enables the investigation of growth control in metazoans because it has conserved metazoan pathways and processes and can be cultured by the thousands in controlled laboratory conditions. We developed a high-throughput phenotyping platform that facilitates a quantitative assessment of C. elegans growth at high precision. Using this platform, we collected growth measurements of thousands of individuals throughout the 72 hours of larval development, measured feeding behavior to pinpoint developmental transitions associated with decreased feeding, and quantified highly accurate changes in animal size and shape during development. We observed simultaneous increases in animal length, decreases in width, and maintenance of volume at each larval transition, suggesting that body shape in addition to size plays a role in the control of C. elegans growth. We propose a model of growth control whereby C. elegans senses body size through physical constraints on cuticle stretch and undergoes larval-stage transitions when the cuticle reaches its maximum capacity for stretch. This work lays the foundation for a mechanistic dissection of how both genetics and environmental cues control organismal growth.