Figure 5. Zygotic replacement of replication coupled H3.2K36 with H3.2R36 does not cause ectopic repression of HOX genes.

1. Chromosomal positions of various histone H3 genes, ash1 and marker transgenes. Twenty‐three histone gene repeat units, each containing single His1, His2B, His2A, His4 and His3.2 gene, are clustered near the centromere (black circle) of chromosome 2. These histone genes are removed by the ΔHisC deletion. To select the animals homozygous for the deletion, the ΔHisC chromosomes are marked with insertions of either Elav‐Gal4 or UAS‐2xYFP transgenes (black triangles on chromosome 2L). The His3.3A and His3.3B genes encode the same protein, but reside on chromosomes 2L and X. The transgenes carrying twelve copies of either the wild‐type histone repeat unit (12x ^WT) or the unit in which H3 gene is altered to have K36 replaced with arginine (12x ^H3K36R) are inserted in the same attP site (black triangle on chromosome 3L) 47. The ash1 gene is located on the same chromosome arm.
2. The ΔHisC; 12x ^H3K36R and control ΔHisC; 12x ^WT flies show no homeotic transformations and are indistinguishable from the wild type.