Fig 2. Sat2-carrying worms can develop in the optimal concentration of nourseothricin.

(A) Schematic of the resistance-marker vector. The vector contains the NTC resistance genes, Sat2 or Nat, under the control of the universal ribosomal promoter, rps-27. (B and C) Ten mCherry-positive P0 worms were placed onto selective or nonselective plates and, after three days of incubation, a 25 mm² slice was excised from each gel and transferred to new selective or nonselective plates, respectively. Transfers were repeated 4-times and the plates were scored three days after the final transfer. (B) Micrographs showing worms carrying Prps-27::Sat2, Pmyo-2::mCherry, Pmyo-3::mCherry and Prab-3::mCherry as an extrachromosomal array. Upper panels show the original bright images of the worms and the mCherry signals. Lower panels, the contrast images to observe mCherry signal. (C) The plot shows the ratios of mCherry-positive to mCherry-negative worms. The results for two independent strains are shown. ****, p < 0.0001, Fisher’s exact test, n = 224 (line #1, 0.00 mg/ml), 226 (line #1, 0.04 mg/ml), 215 (line #2, 0.00 mg/ml) and 273 (line #2, 0.04 mg/ml) worms. Note that most worms have extrachromosomal arrays even after the 4-times transfer when cultured on the NTC-containing plates. In contrast, the extrachromosomal arrays were largely lost from the worms on the non-selection plates.