Figure 5.

Less age-associated defects in the cholinergic neurons of C. elegans fed on Se-enriched E. coli bacteria. The transgenic C. elegans strain LX929, with its cholinergic neurons tagged by GFP, was supplied with either the standard E. coli OP50 diet or with Se-enriched E. coli OP50 for up to 12 days, starting at the L1 stage. The nerve cords of the nematodes were visualized by fluorescence microscopy. (A) At each of the specified days, the fractions of healthy, mildly damaged and severely damaged neurons of 30 nematodes from each group were calculated. Data are depicted as means from three independent experiments. (B) Neurodegeneration index, calculated by weighting the occurrence of mild and severe damages in the neurons. Data are depicted as means ± S.E.M. from three independent experiments; statistical analysis was performed using an unpaired t-test with Welch’s correction (* p < 0.05). (C) Representative photographs of young nematodes who had received the standard E. coli OP50 diet (left panel) or Se-enriched E. coli OP50 (right panel) for 3 days (post L1 stage). (D) Representative photographs of aged nematodes who had received the standard E. coli OP50 diet (left panel) or Se-enriched E. coli OP50 (right panel) for 12 days (post L1 stage). Note the lower extent of damage, e.g., lower numbers of knots (as marked by the white arrows), in the right panel.