TABLE 8

XSEs become dosage compensated after sex is determined

Transcript measured by qRT–PCRa
Genotypesex-1ceh-39fox-1nhr-64b
her-1; xol-1(y9) sdc-2(y74) unc-9 XOc0.8 ± 0.11.3 ± 0.10.9 ± 0.11.1 ± 0.1
sdc-2(y93, RNAi) XXd2.9 ± 0.25.2 ± 0.62.0 ± 0.11.0 ± 0.1
dpy-27(y57) XX1.8 ± 0.11.8 ± 0.21.3 ± 0.11.3 ± 0.1
sex-1(y263) XX0.9 ± 0.1e2.8 ± 0.42.1 ± 0.51.3 ± 0.1
sex-2(y324) XX1.4 ± 0.12.6 ± 0.32.2 ± 0.31.2 ± 0.1
ceh-39(y414) XX1.2 ± 0.13.9 ± 0.41.8 ± 0.21.1 ± 0.1
ceh-39(gk296) XX1.3 ± 0.1NA1.3 ± 0.11.1 ± 0.1
fox-1(y303) XX1.2 ± 0.11.3 ± 0.11.4 ± 0.11.3 ± 0.1
xol-1(y9) sex-1(y263) XX0.9 ± 0.11.8 ± 0.20.9 ± 0.11.1 ± 0.1
yIs58[ceh-39(+)] XX1.0 ± 0.14.1 ± 0.51.1 ± 0.10.9 ± 0.1
yIs58[ceh-39(+)]; sex-1(y263) XX1.0 ± 0.126.4 ± 2.83.6 ± 0.51.2 ± 0.1
yIs58[ceh-39(+)]; xol-1(y9) sex-1(y263) XX1.0 ± 0.13.1 ± 0.32.3 ± 0.21.0 ± 0.1
  • a The levels of XSE transcripts in embryos of different genotypes (listed by genotype) were measured by qRT–PCR and are expressed as the fold change compared to the transcript levels measured in wild-type XX embryos. All transcripts levels were normalized to the levels of the control gene, fatty acid synthase-1 (fasn-1), whose expression is constant throughout embryogenesis and is not affected by dosage compensation. See Van Gilst et al. (2005) for details and protocol. nhr-64, another gene not affected by dosage compensation, was used as a control to gauge the variability and reliability of measurements made using qRT–PCR. Experimental error is expressed as the standard error of the mean. Similar results were obtained for all genotypes in separate qRT–PCR experiments in which transcript levels were normalized to the levels of nhr-64.

  • b A critical control was to compare the fasn-1-normalized nhr-64 transcript levels in three independent preparations of wild-type embryos. That comparison showed the nhr-64 transcript levels to be statistically equivalent among the independent RNA preparations (nhr-64, 1.3 ± 0.1).

  • c The full genotype is her-1(hv1y101); xol-1(y9) sdc-2(y74) unc-9(101) XO.

  • d XX animals carrying the weak sdc-2(y93) mutation were fed sdc-2(RNAi), and the dead, dosage-compensation-defective progeny embryos were harvested for RNA isolation.

  • e The sex-1(y263) mutation affects sex-1 mRNA splicing and may destabilize the mutant sex-1 transcripts, causing a decrease in their overall levels, specifically in sex-1 mutants.