Biolistic Transformation
50 ml Tetrahymena  cultures were grown to 500,000 cells ml-1 and starved for 10–16 h in 10 mM Tris-HCl buffer, pH 7.4, at 30°C with agitation. Biolistic transformations were performed as described previously (Sparvoli et al., 2018, Cassidy-Hanley et al., 1997). Transformants were identified after 3 days selection in paromomycin sulfate (120 μg ml-1 with 1 μg ml-1 of CdCl2), and then serially passaged 5\(\times\)/week for ~4 weeks in decreasing concentrations of CdCl2 and increasing concentrations of paromomycin sulfate.