Scientists discover a conserved mitochondrial RNA shared by zebrafish and humans

Researchers have identified a previously undescribed mitochondrial long noncoding RNA, named lncOriL, that is present in zebrafish and appears to be conserved across vertebrates, including humans. The finding emerged from a detailed characterization of the mitochondrial transcriptome during early zebrafish development, carried out using long-read direct RNA sequencing.

The team, led by Tor Erik Jørgensen and colleagues and published in BMC Molecular and Cell Biology, reports that lncOriL is 313 nucleotides long, polyadenylated, and expressed at an abundance comparable to that of the ND5 messenger RNA. It maps to a region of the mitochondrial genome that covers the origin of light strand replication and four flanking antisense transfer RNA genes.

The zebrafish mitochondrial transcriptome itself proved distinctive but practically invariant between developmental stages. All heavy-strand messenger RNAs carried 3′ poly-A tails of approximately 50 to 60 residues. Three unusual transcripts stood out: the COI and ND5 mRNAs, which possess significant 3′ untranslated regions corresponding to antisense gene sequences, and the newly described lncOriL.

One notable chemical feature concerned ND5 mRNA. The researchers found that this single transcript carried one third of all detected m6A methylation sites in the zebrafish mitochondrial transcriptome, a striking concentration of epitranscriptomic marks on one mitochondrial message.

A further layer of the finding involves a mitochondrial transfer RNA-derived fragment, tiRNA5-Asn, which has a 35-nucleotide perfect pairing potential to lncOriL. This fragment was present at all investigated developmental stages, suggesting a possible regulatory interaction between the two RNAs that the authors propose warrants further experimental investigation.

The zebrafish results were not an isolated observation. Additional analyses including adult zebrafish, scissortail (Rasbora rasbora), and monkfish (Lophius piscatorius) strongly corroborated the prevalence of the COI mRNA, ND5 mRNA, and lncOriL transcript among teleost fish.

Surprisingly, the findings extended beyond fish. Mitochondrial transcriptome analyses in domestic pig (Sus scrofa) and human (Homo sapiens) supported the results, including the presence of tiRNA5-Asn in human tissues. This cross-species consistency underpins the authors’ conclusion that lncOriL appears ubiquitously expressed across vertebrates.

The potential regulation of the RNA by a transfer RNA-derived fragment conserved in both zebrafish and human suggests, in the authors’ words, a previously unrecognized layer of mitochondrial gene expression regulation.

The authors note that the teleost mitochondrial transcriptome remains poorly understood, even though teleost fish and mammals share the same mitochondrial gene content and organization. The study is an open-access research article published on 19 September 2026, and the reported version is an accepted manuscript shared early, subject to further edits before the final version of record. The functional role of lncOriL remains a matter for future experimental work rather than an established mechanism.

Subject of Research: Discovery of a conserved polyadenylated mitochondrial long noncoding RNA in zebrafish and humans

Article Title: lncOriL, a polyadenylated mitochondrial lncRNA common to zebrafish and human

Article References: Jørgensen, T. E., Wardale, A., Profant, S. W., Amundsen, C., Emblem, Å., Joakimsen, I. S., Brekke, O.-L., Karlsen, B. O., Babiak, I., & Johansen, S. D. (2026). lncOriL, a polyadenylated mitochondrial lncRNA common to zebrafish and human. BMC Molecular and Cell Biology. https://doi.org/10.1186/s12860-026-00602-x

Image Credits: AI Generated

DOI: 10.1186/s12860-026-00602-x

Keywords: mitochondrial RNA, lncOriL, zebrafish, transcriptome, long-read RNA sequencing, tiRNA5-Asn, ND5 mRNA, m6A methylation, vertebrates, gene regulation, noncoding RNA, polyadenylated