Figure 1. Delayed Onset of Sxl RNA Synthesis in Haploids.

Haploid 1X;1A (top row) and diploid XX;AA (bottom row) embryos were stained following in situ hybridization. Dots represent nascent transcripts from SxlPe in surface nuclei. Nuclear cycles (12–15) are indicated; e and m denote early (≤5 min) and mid (≤20 min) stages of the cellularization cycles. Haploid embryos cellularize during nuclear cycle 15 and diploids during cycle 14. Cycle 12 and haploid cycle 13 embryos were illuminated with visible and UV light to highlight DAPI-stained nuclei. Embryos were progeny of sibling mh¹/mh¹or mh¹/FM3 females and mh¹/Y males.