Evolution of germ-line signals that regulate growth and aging in nematodes.
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 because of a sink of resources required for reproduction. The C. elegans germ line also emits a signal that represses longevity. This longevity-repressing signal requires the activity of DAF-16, a forkhead/winged-helix transcription factor, 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 transforming growth factor beta-related protein that promotes growth in worms. By ablating the germ-line precursors of other species of free-living nematodes, we also found that both the growth-repressing and longevity-repressing signals are evolutionarily variable. Some species have both signals; 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.
Patel
Mavji N
MN
Department of Biological Science, Imperial College at Silwood Park, Ascot, Berks SL5 7PY, United Kingdom.
Knight
Christopher G
CG
Karageorgi
Constantina
C
Leroi
Armand M
AM
D000375:Aging / Q000235:genetics; D000818:Animals; D000916:Antibody Diversity; D005075:Biological Evolution; D001824:Body Constitution / Q000235:genetics; D017173:Caenorhabditis elegans / Q000235:genetics* / Q000254:growth & development; D029742:Caenorhabditis elegans Proteins / Q000235:genetics; D005260:Female; D051858:Forkhead Transcription Factors; D017238:Genes, Helminth; D008136:Longevity / Q000235:genetics; D008297:Male; D009154:Mutation; D015398:Signal Transduction; D014157:Transcription Factors / Q000235:genetics
D029742:Caenorhabditis elegans Proteins; D051858:Forkhead Transcription Factors; D014157:Transcription Factors; C108831:daf-16 protein, C elegans