Abstract
BackgroundDoubly Uniparental Inheritance (DUI) represents the most outstanding exception to matrilinear inheritance of mitochondrial DNA (mtDNA), typical of Metazoa. In a few bivalve mollusks, two sex-linked mtDNAs (the so-called M and F) are inherited in a peculiar way: both daughters and sons receive their F from the mother, whereas sons inherit M from the father (males do not transmit F to their progeny). This realizes a double mechanism of transmission, in which M and F mtDNAs are inherited uniparentally.DUI systems represent a unique experimental model for testing the evolutionary mechanisms that apply to mitochondrial genomes and their transmission patterns as well as to mtDNA recombination.ResultsA new case of DUI is described in Musculista senhousia (Mollusca: Bivalvia: Mytilidae). Its heteroplasmy pattern is in line with standard DUI. Sequence variability analysis evidenced two main results: F haplotypes sequence variability is higher than that of M haplotypes, and F mitochondrial haplotypes experience a higher mutation rate in males' somatic tissues than in females' ones. Phylogenetic analysis revealed also that M. senhousia M and F haplotypes cluster separately from that of the other mytilids.ConclusionSequence variability analysis evidenced some unexpected traits. The inverted variability pattern (the F being more variable than M) was new and it challenges most of the rationales proposed to account for sex-linked mtDNA evolution. We tentatively related this to the history of the Northern Adriatic populations analyzed. Moreover, F sequences evidenced a higher mutation level in male's soma, this variability being produced de novo each generation. This suggests that mechanisms evolved to protect mtDNA in females (f.i. antioxidant gene complexes) might be under relaxed selection in males. Phylogenetic analysis of sex-linked haplotypes confirmed that they have switched their roles during the evolutionary history of mytilids, at variance to what has been observed in unionids. Consequently, reciprocal monophyly of M and F lineages got easily lost because of role-reversals and consequent losses of M lineages, as already observed in Mytilus.
Highlights
Uniparental Inheritance (DUI) represents the most outstanding exception to matrilinear inheritance of mitochondrial DNA, typical of Metazoa
A new case of Doubly Uniparental Inheritance (DUI) is described in Musculista senhousia (Mollusca: Bivalvia: Mytilidae)
The inverted variability pattern was new and it challenges most of the rationales proposed to account for sex-linked mitochondrial DNA (mtDNA) evolution
Summary
Uniparental Inheritance (DUI) represents the most outstanding exception to matrilinear inheritance of mitochondrial DNA (mtDNA), typical of Metazoa. In the Mytilus edulis species complex (i.e. Mytilus edulis, M. galloprovincialis, M. trossulus) the coinheritance of the female and the male mitochondrial genomes have been largely demonstrated and, in more detail, both daughters and sons get the F genome from the mother, whereas sons only inherit and transmit the M genome of the father. This peculiar mtDNA inheritance pattern is known as Doubly Uniparental Inheritance (DUI; [4,5]) or gender-associated inheritance [2,3]. Evidences of both neutral and non-neutral evolution have been found in different Mytilus taxa and populations, results that were considered in line with a nearly neutral model of molecular evolution (see discussion)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
