Neurodegeneration occurs in <i>C. elegans</i> following exposure to <i>S. venezuelae</i> conditioned medium.

<p>A. An isogenic worm strain expressing GFP in DA neurons was examined for DA neurodegeneration four and six days after exposure to <i>Streptomyces</i> spp. conditioned media. Significant DA neurodegeneration only occurred from exposure to <i>S. venezuelae</i> conditioned medium (*<i>P</i><0.05; ANOVA). B. Photomicrographs of GFP-labeled DA neurons from <i>C. elegans</i> exposed to bacterial conditioned medium for six days. All six anterior DA neurons in <i>C. elegans</i> exhibit degenerative changes following exposure to <i>S. venezuelae</i> but not <i>E. coli</i> (control) medium (the four CEP class of DA neurons and the two ADE class of DA neurons are indicated with arrows and arrowheads, respectively). C. Populations of isogenic worm strains expressing GFP exclusively in 5-HT, GABA, ACh, Glut, and DA (+ and –TH) neuronal classes were examined for neurodegeneration. The only animals that displayed significant neurodegeneration after six days exposure to <i>S. venezuelae</i> conditioned medium were those in which the DA (+TH) neurons were analyzed (*<i>P</i><0.01; ANOVA). These data were standardized against the amount of degeneration observed from exposure to <i>E. coli</i> control conditioned medium. D. At eight days of exposure to <i>S. venezuelae</i> conditioned medium, all neuronal classes examined exhibited significant degeneration (*<i>P</i><0.01; ANOVA). These data were standardized against the amount of degeneration observed from exposure to <i>E. coli</i> control conditioned medium. Because each neuronal class contains varying numbers of neurons, this analysis was based on the percentage of degenerating neurons (not degenerating worms, as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0007227#pone-0007227-g001" target="_blank">Fig. 1C</a>) to compensate for differences in total neuron numbers. Furthermore, DA neurons still exhibited significantly more degeneration than other neuronal classes (*<i>P</i><0.05; ANOVA). All graphical data in this figure are represented as mean degeneration +/− S.E.M. Scale bar = 50 µM.