Pursuing the quest for better understanding the taxonomic distribution of the system of doubly uniparental inheritance of mtDNA.

Arthur Gusman,Sophia Lecomte,Sophie Breton,Marco Passamonti,Donald T Stewart

doi:10.7717/peerj.2760

Abstract

There is only one exception to strict maternal inheritance of mitochondrial DNA (mtDNA) in the animal kingdom: a system named doubly uniparental inheritance (DUI), which is found in several bivalve species. Why and how such a radically different system of mitochondrial transmission evolved in bivalve remains obscure. Obtaining a more complete taxonomic distribution of DUI in the Bivalvia may help to better understand its origin and function. In this study we provide evidence for the presence of sex-linked heteroplasmy (thus the possible presence of DUI) in two bivalve species, i.e., the nuculanoid Yoldia hyperborea(Gould, 1841)and the veneroid Scrobicularia plana(Da Costa,1778), increasing the number of families in which DUI has been found by two. An update on the taxonomic distribution of DUI in the Bivalvia is also presented.

Highlights

Strict maternal inheritance (SMI) is considered to be the paradigm for mitochondrial DNA transmission in animal species (Birky, 2001)
doubly uniparental inheritance (DUI) is characterized by the presence of two distinct sex-associated mitochondrial lineages: the female type (F mitochondrial DNA (mtDNA)), which is transmitted through the eggs to all offspring, and the male type (M mtDNA) which is present in sperm, enters all eggs at the time of fertilization, but is only retained and transmitted through male offspring
Some major features of DUI are quite well known—for example species with DUI show strong sex biases in offspring towards one or the other sex following parental crosses (e.g., Kenchington et al, 2002; Kenchington et al, 2009), both F and M lineages show rapid molecular evolution compared to other animals, the M mtDNA usually evolves faster than the F mtDNA, M mitochondria show sex-specific behavior in newly formed zygotes, and novel mtDNA-encoded protein-coding genes have been found in species with DUI (Breton et al, 2007; Passamonti & Ghiselli, 2009; Zouros, 2013; Breton et al, 2014)—the main function of this peculiar system of mtDNA transmission still remains undetermined

Summary

Introduction

Strict maternal inheritance (SMI) is considered to be the paradigm for mitochondrial DNA (mtDNA) transmission in animal species (Birky, 2001). The F-type mtDNA is predominant in all tissues of both sexes, except in the male gonad where the M-type mtDNA prevails; some exceptions have been documented, adult females are essentially homoplasmic and adult males are heteroplasmic (reviewed in Breton et al, 2007; Passamonti & Ghiselli, 2009; Zouros, 2013). The stability of this system of heredity across evolutionary time in several. Sustained by the correlation between DUI and gonochorism (and the absence of DUI and hermaphroditism), one main hypothesis suggests a link between this model of heredity and the maintenance of separate sexes (Breton et al, 2011a)

Methods

Results

Conclusion