Figure 4.—

MSL1 and MSL3, but not MSL2, are required for full expression of autosomal genes. (A) Fourth-linked and heterochromatic genes are not misregulated in msl2¹ male larvae. Box plots represent the log₂ (mutant:control) expression of the indicated groups of genes. Expression was measured by hybridizing microarrays with probes generated from msl2¹ and msl2¹/+ (control) male larvae. Enrichment for heterochromatic genes is described in materials and methods. (B) Fourth-linked and heterochromatic genes require MSL1 for full expression. Expression of a panel of genes was measured in msl1¹ males and their heterozygous brothers (controls). Seven euchromatic genes on the second and third chromosomes; 4 euchromatic X-linked genes, 12 fourth-linked genes, and 10 heterochromatic genes on the second and third chromosome were assayed (see Table S1). Expression of heterochromatic and fourth-linked genes differs from euchromatic genes on the second and third chromosomes at the 0.003 and 0.002 confidence level, respectively. (C) Fourth-linked and heterochromatic genes require MSL3 for full expression. Expression of a panel of genes was measured in msl3² males and their heterozygous brothers (controls). Seven euchromatic genes on the second and third chromosomes, 4 euchromatic X-linked genes, 13 fourth-linked genes, and 10 heterochromatic genes were measured. Expression of heterochromatic and fourth-linked genes differs significantly from euchromatic genes on the second and third chromosomes at the 0.032 and 0.036 confidence levels. Dmn was used to normalize amplification. Box plots were generated using Bioconductor R. See materials and methods for details of statistical analyses.