Fig. 3. Analysis of NSM serotonin immunoreactivity in adult hermaphrodites. (A,B) In wild-type animals, nine neurons of five classes were stained by the anti-serotonin antibody. In general, the frequency of the AIM and RIH neurons stained is lower than of NSM, ADF and HSN, and the intensity of the staining in AIM and RIH is often lower. (C,D) In unc-86-null mutants, serotonin immunoreactivity in NSM and ADF remained, unlike in AIM, RIH and HSN. The ADF neurons are the only class of the serotonergic neurons that does not express unc-86, and unc-86 mutations had no effect on ADF serotonin immunoreactivity. (E,F) Treatment of animals with the serotonin reuptake block drug imipramine significantly reduced NSM but not ADF serotonin immunoreactivity in unc-86 mutants (E), and this effect was not observed in wild-type animals treated with imipramine at the same concentration (F). (G) No serotonin could be detected in the unc-86(e1416);nss-1(yz12) double mutant. unc-86(n846); nss-1(yz12) showed similar staining pattern (not shown). (H) The nss-1(yz12) mutation specifically affects serotonin immunoreactivity in ADF. Adult animals are shown, and the anterior is towards the left. For each strain, the immunostaining was performed many times, and quantification of the observation from two recent trials is presented in Table 1.