Mitogenomics and Mitochondrial Inheritance 

Mitogenomics

The mitochondrial genome (mtDNA) is a good model system for evolutionary genomic studies, and the availability of more than 1000 sequences (at present) provides an almost unique opportunity to decode mechanisms of genome evolution over a large phylogenetic range. Several structural genomic features (for example genome size, gene content, gene order, compositional features, nucleotide substitution rate, repeated sequences, non-coding sequences, secondary structure of the encoded RNA) can be systematically and quite easily investigated in the small mitochondrial genome. These features allow both the description of evolutionary trends in phylogenetically distant organisms and the identification of functional constraints that might account for structural differences. Our research group studies mt genome structure and evolution in bivalves and basal pterygote insects, such as stick insects (Phasmida), as a part of a large collaboration project aimed to fill the taxonomic gaps in the characterization of mitochondrial DNA in metazoans.

  Mitochondrial Inheritance and DUI

Eukaryotes have exploited several mechanisms for organelle uniparental inheritance, so that this feature arose and evolved independently many times in their history. Metazoans’ mitochondria commonly experience Strict Maternal Inheritance (SMI), i.e. they are only transmitted by females. One of the main biological questions is how and why uniparental inheritance has evolved for organelle DNA. The most noteworthy exception to SMI comes from some bivalve mollusks, in which two mitochondrial lineages (together with their genomes) are inherited, one through females (F), the other through males (M). This inheritance mechanism is known as Doubly Uniparental Inheritance (DUI), since both sexes inherit uniparentally their mitochondria. DUI is a choice model to address many aspects that should be of interest to a wide range of biological sub-fields, such as mitochondria inheritance, mtDNA evolution and recombination, genomic conflicts, evolution of sex, developmental biology, etc. Actually, as researches proceed, mitochondria appear to have acquired a central role in many fundamental processes of life, which are not only in their metabolic activity as cellular power plants, such as cell signaling, fertilization, development, differentiation, ageing, apoptosis and sex determination. A function of mitochondria in the origin and maintenance of sex has been also proposed.