[
International C. elegans Meeting,
2001]
One of the least understood aspects of animal development is how growth and body size are regulated 1,2 . Here we show that a signal from the germ-line represses growth in the nematode Caenorhabditis elegans . Laser-microbeam ablation of cells that give rise to the germ-line causes adults to become giant. Ablation of these cells in self-sterile mutant worms also causes gigantism suggesting that the germ-line represses growth because it is the source of a growth-antagonizing signal rather than a sink of resources required for reproduction. The C. elegans germ-line also emits a signal that represses longevity 3 . This longevity-repressing signal requires the activity of DAF-16, a forkhead/winged-helix transcription factor 3 , but we find that that the growth-repressing signal does not. The growth-repressing signal also does not require the activity of DBL-1, a TGF-beta-related protein that promotes growth in worms 4,5 . By ablating the germ-line precursors of other species of free-living nematodes we found that both the growth-repressing and longevity-repressing signals are evolutionarily variable. Some species have both, others have just one or the other. We suggest that variation in germ-line signaling contributes to body size and life-history diversity in the nematodes. 1. I, Conlon, M. Raff, Cell 96, 235 (1999). 2. S. J. Day, P. A. Lawrence, Development 127, 2977 (2000). 3. H. Hsin, C. Kenyon, Nature 399 , 362 (1999). 4. K. Morita, K. L. Chow, N. Ueno, Development 126, 1337 (1999). 5. Y. Suzuki et al ., Development 126, 241 (1999).