Figure 2.

Immunofluorescence of fixed Oxytricha trifallax cells during genome rearrangements. (a) A methylcytosine signal appears during the 30-40 h (hour) window. Cells are staged by the nuclear morphology observed in single, well-timed cells. The micronucleus (I), parental macronucleus (A) and zygotic macronucleus (Z) are all indicated. (b) Co-immunofluorescence analysis shows co-localization of methylcytosine and hydroxymethylcytosine. (c) Quantification of methylcytosine-containing DNA-rich bodies (the parental macronucleus) in the 46 h population shown in (a), separated by cell stage. (d). Co-immunofluorescence with methylcytosine and anti-Otiwi1, a temporal marker for zygotic macronucleus development. Note the temporal separation of Otiwi1 and DNA methylation during the transition between S1 and S3. (e) The nuclear morphology criteria used in (a) - (d) for staging cells. MAC, macronucleus; Veg, vegetative.