• body size;
  • TGFβ;
  • BMP;
  • Caenorhabditis elegans;
  • mutant screen


In the nematode Caenorhabditis elegans, a TGFβ-related signaling pathway regulates body size and male tail morphogenesis. We sought to identify genes encoding components or modifiers of this pathway in a large-scale genetic screen. Remarkably, this screen was able to identify essentially all core components of the TGFβ signaling pathway. Among 34 Small mutants, many mutations disrupt genes encoding recognizable components of the TGFβ pathway: DBL-1 ligand, DAF-4 type II receptor, SMA-6 type I receptor, and SMA-2, SMA-3, and SMA-4 Smads. Moreover, we find that at least 11 additional complementation groups can mutate to the Small phenotype. Four of these 11 genes, sma-9, sma-14, sma-16, and sma-20 affect male tail morphogenesis as well as body size. Two genes, sma-11 and sma-20, also influence regulation of the developmentally arrested dauer larval stage, suggesting a role in a second characterized TGFβ pathway in C. elegans. Other genes may represent tissue-specific factors or parallel pathways for body size control. Because of the conservation of TGFβ signaling pathways, homologs of these genes may be involved in tissue specificity and/or crosstalk of TGFβ pathways in other animals. genesis 35:239–247, 2003. © 2003 Wiley-Liss, Inc.