Analysis of candidate Aplysia californica chemosensory receptors subfamily b. (a) Conservation of predicted amino acid sequences for 38 full-length genes is displayed as a consensus strength as color-coded histogram. In this representation, the relative frequency with which an amino acid appears at a given position is reflected by the color, as depicted by the scale bar. The seven transmembrane domains (based on the HMMTOP version 2.0 program) are indicated by a solid bar above the sequence. (b) Schematic representation of the genome organization of clustered genes AcCR11b and AcCR12b (genomic contig AASC01159697), including predicted start (ATG) and stop codons (TAG). (c) Similar to (b) but clustered genes AcCR13b and AcCR14b (genomic contig AASC01064969). A predicted retrotransposon element is identified in the reverse orientation between the two gene sequences (see Figure S1 in Additional file 3). Met, methionine.