Fig. 1

Gene maps and organization of the complete mitochondrial genomes of Radix swinhoei (a) and Planorbarius corneus (c). The outer and the inner circles represent the positive (H-strand) and the negative (L-strand) strand, respectively. The tRNA genes are named using single-letter amino acid abbreviations as shown in the Tables (b, d). ^aIndicates that the gene is encoded by H or L strand; ^b Intergenic nucleotides, indicates the number of nucleotides separating a gene from the one upstream of it; negative numbers indicate an overlap between the adjacent genes; ^cIncomplete termination codon, which might probably be extended by post-transcriptional adenylation; ^dRepresent the presence of repeat masker