Figure 7. Sex chromosomes are especially vulnerable to HP1E depletion in D. melanogaster.
Representative images of fluorescent in situ hybridization (FISH) analyses of first zygotic telophase in (A) wild-type and (B) PEL embryos using chromosome-specific satellite probes (C), which recognize chromosome-specific repetitive elements (Dernburg, 2011). FISH probes against the Y chromosome were tested together with probes against either the chr. X probe (left) or chr. 2 + 3 probe (middle) or chr. 4 probe (right). (D) Using at least 20 images per probe pair per sex, we find that sex chromosomes are statistically enriched in the telophase bridge of PEL embryos. Quantification of chromosomal element appearance in the first telophase bridge in male and female embryos (PEL embryos) fathered by HP1E-depleted males. Hybridization of the fourth chromosome probe to the Y chromosome precluded data collection for this probe in male embryos. Data are reported as ‘obs/total/(%)’ where ‘obs’ = number of embryos observed with the probe appearing in the telophase bridge, ‘total’ = total number of embryos sampled per probe, and ‘%’ = obs × 100/total.