Scientists mapped the full mitochondrial DNA and RNA of the anglerfish and found lots of ribosomal RNA, unusually high levels of certain protein‑coding RNAs, and some new long non‑coding RNAs. They also spotted a tiny peptide that looks like the human longevity peptide humanin, but it’s in fish mitochondria and its function isn’t known for humans.

Analyze key features of the anglerfish Lophius piscatorius mitochondrial transcriptome based on high-throughput total RNA sequencing. We determined the complete mitochondrial DNA and corresponding transcriptome sequences of L. piscatorius. Key features include highly abundant mitochondrial ribosomal RNAs (10-100 times that of mRNAs), and that cytochrome oxidase mRNAs appeared > 5 times more abundant than both NADH dehydrogenase and ATPase mRNAs. Unusual for a vertebrate mitochondrial mRNA, the polyadenylated COI mRNA was found to harbor a 75 nucleotide 3' untranslated region. The mitochondrial genome expressed several non-canonical genes, including the long noncoding RNAs lncCR-H, lncCR-L and lncCOI. Whereas lncCR-H and lncCR-L mapped to opposite strands in a non-overlapping organization within the control region, lncCOI appeared novel among vertebrates. We found lncCOI to be a highly abundant mitochondrial RNA in antisense to the COI mRNA. Finally, we present the coding potential of a humanin-like peptide within the large subunit ribosomal RNA.