An evolutionary preserved intergenic spacer in gadiform mitogenomes generates a long noncoding RNA

• Published in: BMC Evolutionary Biology
• Main Authors: Jørgensen, Tor Erik, Bakke, Ingrid, Ursvik, anita, Andreassen, morten, Moum, Truls, Johansen, Steinar Daae
• Format: Article in Journal/Newspaper
• Language: English
• Published: BioMed Central 2015
• Subjects: Hake; atlantic cod
• Online Access: http://hdl.handle.net/11250/275754; https://doi.org/10.1186/s12862-014-0182-3

The electronic version of this article is the complete one and can be found online at: http://www.biomedcentral.com/1471-2148/14/182 Background: Vertebrate mitogenomes are economically organized and usually lack intergenic sequences other than the control region. Intergenic spacers located between the tRNAThr and tRNAPro genes (“T-P spacers”) have been observed in several taxa, including gadiform species, but information about their biological roles and putative functions is still lacking. Results: Sequence characterization of the complete European hake Merluccius merluccius mitogenome identified a complex T-P spacer ranging in size from 223–532 bp. Further analyses of 32 gadiform species, representing 8 families and 28 genera, revealed the evolutionary preserved presence of T-P spacers across all taxa. Molecular complexity of the T-P spacers was found to be coherent with the phylogenetic relationships, supporting a common ancestral origin and gain of function during codfish evolution. Intraspecific variation of T-P spacer sequences was assessed in 225 Atlantic cod specimens and revealed 26 haplotypes. Pyrosequencing data representing the mito-transcriptome poly (A) fraction in Atlantic cod identified an abundant H-strand specific long noncoding RNA of about 375 nt. The T-P spacer corresponded to the 5’ part of this transcript, which terminated within the control region in a tail-to-tail configuration with the L-strand specific transcript (the 7S RNA). Conclusions: The T-P spacer is inferred to be evolutionary preserved in gadiform mitogenomes due to gain of function through a long noncoding RNA. We suggest that the T-P spacer adds stability to the H-strand specific long noncoding RNA by forming stable hairpin structures and additional protein binding sites. Forlagets publiserte versjon. Open access. © 2014 Jørgensen et al.; licensee BioMed Central Ltd.This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.