Sensory neuron-specific genes are less likely to be classified into Gene Ontology categories and more likely to be worm-specific. (a) All genes on the microarray were ordered by descending che-2::PABP/acr-5::PABP value and the fraction of GO-annotated genes in each bin is indicated for a bin width of 50 rank orders. Only the top 1,500 genes are shown in (a)-(c). (b) The fraction of genes with homologs in C. briggsae, and not in humans, mice, flies, fission yeast or budding yeast (cutoff BLASTP score E = 1 × 10-20) in each bin is indicated as in (a). (c) The fraction of genes with homologs in both animals and yeasts, namely in humans, mice or flies and in fission yeast or budding yeast (cutoff BLASTP score E = 1 × 10-20) in each bin is indicated as in (a). In all panels, the red dotted line indicates the average of all the genes, and the blue dotted lines indicate the 95% confidence limits assuming a random binominal distribution.