Figure 1.

Iron depletion induces LIT1 expression and LIT1-dependent inhibition of replication. (A) Immunofluorescence with anti-LIT1 antibodies of live WT and Δlit1 promastigotes after 24-h incubation in iron-depleted medium. The arrows point to promastigotes expressing LIT1 on the cell surface. Bars, 6 µm. (B) qPCR detection of LIT1 transcripts in WT promastigotes at different periods after iron depletion. (C) WT promastigotes grown in regular media to mid-log phase were incubated in iron-depleted medium for 6 h, harvested, and resuspended in iron-depleted medium supplemented or not with 8 µM Fe-NTA, 5 µM hemin, or 8 µM Fe-NTA/5 µM hemin. After 14 h, total RNA was isolated from 10⁸ cells harvested from each culture, and LIT1 transcript levels were determined by qPCR. *, P < 0.0125; **, P < 0.0075 (Student’s t test). (D) WT or Δlit1 promastigotes grown to mid-log in regular medium were used to initiate cultures in iron-depleted medium. The growth rates of WT and Δlit1 strains under iron-depleted conditions were determined by microscopic counting of viable cells at the indicated time points. (B–D) The data represent the mean ± SD of triplicate determinations and are representative of three independent experiments.