Mechanisms of <i>VSG</i> switching in WT and short-telomere isolates.

<p>(A) Cartoon depicting the critical details of the three predominant mechanisms of <i>VSG</i> switching- IS (In situ), TE (telomere exchange), and GC (duplicative gene conversion). Large arrowhead indicates active promoter; small arrowhead depicts the silent promoter; dashed line indicates transcription; orange box shows the position of the antibiotic selection marker. <i>VSG427-2</i> nomenclature is used interchangeably with its colloquial name <i>VSG221</i> (B) OSF of the populations of WT (blue, n = 12 populations) and <i>TERT^−/−</i> short-telomere (green, n = 6 populations) switchers. (C) Percent of WT (blue, n = 189) and <i>TERT^−/−</i> short-telomere (green, n = 188) <i>VSG</i> switched isolates versus switching mechanism: IS (in situ), GC (all gene conversion = GC+ES−GC), TE (telomere exchange), or UD (undetermined). Percent loss of BES1 <i>VSG</i> pseudogene from GC (“Ψ− GC+”) switched isolates (WT n = 26 & Short n = 149) is shown beyond the broken line (WT, lined blue bar & short-telomere, lined green bar). (D) RAGE separated chromosomes blotted and probed with <i>VSG</i> specific probes for a subset of <i>TERT^−/−</i> short-telomere switched clones.