The atypical presence of the paternal mitochondrial DNA in somatic tissues of male and female individuals of the blue mussel species Mytilus galloprovincialis

<p>Abstract</p> <p>Background</p> <p>In animals mtDNA inheritance is maternal except in certain molluscan bivalve species which have a paternally inherited mitochondrial genome (genome M) along with the standard maternal one (genome F). Normally, the paternal genome occurs in the male gonad, but it can be often found, as a minority, in somatic tissues of males and females. This may happen in two ways. One is through "sperm mtDNA leakage" into somatic tissues, a deviation from the normal situation in which the sperm mtDNA vanishes in females or ends up exclusively in the germ line of males. The other is through "egg heteroplasmy", when the egg contains, in small quantities, the paternal genome in addition to maternal genome.</p> <p>Findings</p> <p>To test the two hypotheses, we compared the sequences of one of the most variable domains of the M molecule in a somatic tissue (foot) and in the sperm of ten male and in the foot of ten female individuals of <it>M. galloprovincialis</it>. Presence of the M genome was rarer in the foot of females than males. The M genome in the sperm and in the foot of males was identical.</p> <p>Conclusions</p> <p>Given that the surveyed region differs from individual to individual, the identity of the M genome in the foot and the sperm of males supports strongly the hypothesis that, at least for the tissue examined, the presence of the M genome is due to sperm mtDNA leakage.</p

Female-dependent transmission of paternal mtDNA is a shared feature of bivalve species with doubly uniparental inheritance (DUI) of mitochondrial DNA

Several species from a number of bivalve molluscan families are known to have a paternally transmitted mitochondrial genome, along with the standard maternally transmitted one. The main characteristic of the phenomenon, known as doubly uniparental inheritance (DUI), is the coupling of sex and mtDNA inheritance: males receive both genomes but transmit only the paternal to their progeny; females either do not have the paternal genome or, if they do, they do not transmit it to their progeny. In the families Mytilidae and Veneridae, both of which have DUI, a female individual is either female-biased (it produces only, or nearly so, female progeny), male-biased (it produces mainly male progeny) or non-biased (it produces both genders in intermediate frequencies). Here we present evidence for a same pattern in the freshwater mussel, Unio delphinus (Unionidae). These results suggest that the maternal control of whether a fertilized egg will develop into a male or a female individual (and the associated feature of whether it will inherited or not inherit the paternal mtDNA) is a general characteristic of species with DUI.Peer reviewe

Paternal mtDNA and Maleness Are Co-Inherited but Not Causally Linked in Mytilid Mussels

BACKGROUND: In marine mussels of the genus Mytilus there are two mitochondrial genomes. One is transmitted through the female parent, which is the normal transmission route in animals, and the other is transmitted through the male parent which is an unusual phenomenon. In males the germ cell line is dominated by the paternal mitochondrial genome and the somatic cell line by the maternal. Research to date has not allowed a clear answer to the question of whether inheritance of the paternal genome is causally related to maleness. METHODOLOGY/PRINCIPAL FINDINGS: Here we present results from hybrid crosses, from triploid mussels and from observations of sperm mitochondria in fertilized eggs which clearly show that maleness and presence of the paternal mitochondrial genome can be decoupled. These same results show that the female mussel has exclusive control of whether her progeny will inherit the mitochondrial genome of the male parent. CONCLUSIONS/SIGNIFICANCE: These findings are important in our efforts to understand the mechanistic basis of this unusual mode of mitochondrial DNA inheritance that is common among bivalves

The correlation between rates of vaccination and rates of acceptance of the theory of evolution

The proportion of people who were fully vaccinated against Covid-19 by February 2022 varied among the countries of the European Union. It is shown here that this proportion is inversely related to the rate of acceptance of the theory of evolution in these countries

No Evidence for Absence of Paternal mtDNA in Male Progeny From Pair Matings of the Mussel Mytilus galloprovincialis

The claim that a Mytilus galloprovincialis male failed to transmit mtDNA to its sons in controlled crosses is shown to be false. At present there is no evidence for mussel males lacking a paternal mtDNA. This makes unlikely the hypothesis that maternal genomes may become paternally transmitted by invading the germ line of males that lack a paternal genome