SURFACTANT STIMULATION OF GROWTH IN THE NEMATODE CAENORHABDITIS-ELEGANS

Size fractionation has been used to isolate L1/L2 larvae from mixed cu ltures of the nematode, Caenorhabditis elegans. Worm lengths have been compared during growth in synchronized liquid and agar cultures. Supp lementation of liquid S medium with 10 ppm surfactant (Pluronics F-68, F-127, F-38, L-35; Tween-20 or Triton X-100) promoted a significant s timulation of growth over three clays in all cases. Because of possibl e poor nutrition and/or aeration in liquid culture, experiments were r epeated using the same surfactants in standard NGM agar. Four surfacta nts again stimulated worm growth significantly whereas two (Tween-20 a nd Pluronic F-68) did not. Differences between these surfactants were also demonstrated with respect to: (i) toxicity; (ii) induction of str ess responses in a transgenic hsp/reporter strain; and (iii) stimulati on of amino acid incorporation into soluble protein both initially and after 41 h of surfactant treatment. These surfactants, and in particu lar, Pluronic F-127, are potentially valuable as culture supplements f or enhancing nematode larval growth. Possible mechanisms for growth pr omotion by surfactants are discussed in light of the fixed somatic cel l lineage and the fact that Pluronic F-127 did not speed up maturation from L4 larvae into egg-bearing adults. (C) 1997 by Elsevier Science Inc.