Structure of the mitochondrial genome of Flustra foliacea (GenBank accession number JQ061319). The arrows indicate the direction of transcription. Numbers indicate noncoding nucleotides between genes (negative values refer to gene overlaps). The tRNA genes are named using single-letter amino acid abbreviations. Those coding for leucine, serine and tryptophan are named L1 for the tRNALeu(CUN) (anticodon UAG) gene, L2 for the tRNALeu(UUR) (anticodon UAA) gene, S1 for the tRNASer(AGN) (anticodon UCU) gene, S2 for the tRNASer(UCN) (anticodon UGA) gene, and W1 for the tRNATrp(UGR) (anticodon UCA) gene and W2 for the tRNATrp(UGR) (anticodon UCA) gene. The genomic features are described in the table on the right. a: Start and end positions of rRNA genes and MNCR determined by boundaries of adjacent genes. b: Incomplete termination codon, which is probably extended by post-transcriptional adenylation.