Characteristics of mitochondrial DNA of unionid bivalves (Mollusca: Bivalvia: Unionidae). I. Detection and characteristics of doubly uniparental inheritance (DUI) of unionid mitochondrial DNA

Abstract

Doubly Uniparental Inheritance (DUI), a peculiar way of inheritance of mitochondrial DNA in animals, has been detected in seven families of marine and freshwater bivalves, including Unionidae. DUI involves two independently inherited mitochondrial genomes: maternal (F genome) and paternal (M genome), which show different tissue localisation and wide genetic variation. F genomes occur in somatic tissues of both sexes and are inherited maternally (Strict Maternal Inheritance, SMI). M genomes are located in male germ cells and transmitted to next generations along the male lineage, i.e. from fathers to male offspring. The objective of this study was detection of M genomes and characteristics of DUI in unionid bivalves from Poland, based on sequential analyses of seven mitochondrial genes. This is the study to analyse F and M haplotypes at intra-and interspecific level in seven species of freshwater mussels. DUI was first observed in species of the genus Unio (U. crassus, U. pictorum and U. tumidus), and the best M haplotype marker was gene cox1. In the studied bivalves F and M sequences showed a similar intraspecific variation, with differences among the genes. Three tRNA genes showed the smallest (ca. 20%) nucleotide variation, followed by the gene coding for RNA for the small ribosomal subunit, srRNA (24%); a significantly greater variation (exceeding 30%) was recorded for protein-coding genes (cox1, cytb) and the gene coding for RNA for the large ribosomal subunit, lrRNA. Interspecific variation of F sequences of the studied unionids ranged from 5% for tRNAs to 18% for cytb. Higher values were observed for M sequences: from 7% for tRNAs to 19% for cox1. The Chinese mussel occurring in Poland, despite the morphology-based identification as Anodonta / Sinanodonta woodiana, proved to be genetically more similar to A. arcaeformis than to Asian specimens of A. woodiana. Phylogenetic analyses showed that in the genus Unio the youngest species were U. pictorum and U. mancus, and the earliest species was U. tumidus showing the greatest genetic distinctness.

Bad taxonomy can kill : molecular reevaluation ofUnio mancusLamarck, 1819 (Bivalvia : Unionidae) and its accepted subspecies

“…Specimens from the Italian lake cluster in clade 2. Sequences of specimens identified as U. pictorum by Soroka (2010) all clustered in clade 3 together with our own material of U. pictorum. Average divergence within the U. pictorum clade was 0.3% (max: 1%), average divergence within the U. mancus clade was 0.5% (max 1.3%), minimum distance between U. mancus and U. pictorum was 2.9%.…”

Chinese pond mussel Sinanodonta woodiana (Lea, 1834) (Bivalvia): origin of the Polish population and GenBank data

“…Specimens of S. woodiana from 5 analysed Polish populations had identical sequences of the mitochondrial cox1 gene fragment. They did not differ from those of individuals from other populations in Poland (Soroka, 2010), Hungary, Italy, and Ukraine (Tab. 1, Fig.…”

“…So far, studies of European species of Unionidae have revealed a low variation within the cox1 gene (less than 1%) in Unio gibbus, U. pictorum and U. tumidus, as well as Anodonta anatina (Källeresjö et al, 2005, Araujo et al 2009, Soroka 2008b, 2010. A higher intraspecific variation of the cox1 gene was reported for the gastropod Sadleriana fluminensis (3%) (Szarowska and Falniowski, 2013) and Potamilus species (2.6%) (Roe and Lydeard, 1998).…”

“…Currently it is assigned to the genus Sinanodonta Modell, 1945 (Beran, 1997(Beran, , 2008Bohme, 1998;Falkner et al, 2001;Yurishinets and Korniushin, 2001;Domagała et al, 2007;Gąbka et al, 2007;Popa et al, 2007;Munjiu and Shubernetski, 2008;Cappelletti et al, 2009;Soroka, 2010;Popa et al, 2011). Mitochondrial cytochrome c oxidase subunit I gene cox1 is used most often for species identification and phylogenetic analyses.…”

Doubly uniparental inheritance and highly divergent mitochondrial genomes of the freshwater mussel Unio tumidus (Bivalvia: Unionidae)

“…The presence of DUI in this species was confirmed but only individual mitochondrial genes have been characterized (Soroka, 2010b). Here we present, sequenced for the first time, the complete sequences of both genomes, first such case in the genus Unio and second among European Unionidae after Anodonta anatina (Soroka & Burzynski, 2015.…”