Nematode autofluorescence and its use as an indicator of viability

Representatives of 15 nematode genera were viewed with 450-490-nm epi-illumination and found to autofluoresce. The autofluorescence was limited to 1-5-mum-d globules in the intestinal cells of live nematodes. When adult Pratylenchus penetrans or Caenorhabditis elegans were killed with formaldehyde, freezing, or heat, autofluorescence dispersed throughout the body. Mixed stages of P. penetrans were killed by freezing at several different temperatures. Estimates of survival based on autofluorescence dispersal matched estimates based on mobility more closely than did estimates based on the vital stain, eosin-y.