FIGURE 7.

Treatment of oocytes with Chaetocin mimics natural aging: Young prophase I‐arrested mouse oocytes (9 animals were used for this experiment) were released to resume meiosis in a medium supplemented with Chaetocin that inhibits heterochromatin formation (see Methods). (a) The resulting phenotype was measured by the assessment of maturation efficiency of treated oocytes compared with untreated controls (Z test p = 0.008). Incubation with Chaetocin requires sealing of the plate for bio‐safety reasons. Therefore, an additional control with a sealed plate but without the drug was added (see Methods). (b) Activation of L1 retrotransposons following Chaetocin treatment was measured by immunofluorescence for L1‐ORF1p in young MII mouse oocytes with or without Chaetocin (MW p = 0.0007) (c) To measure RNA processing activity in Chaetocin‐treated oocytes, in situ staining was performed for dsRNA in young MII mouse oocytes with or without Chaetocin. (MW p = 0.02)