Abstract
The complete sequences of three mitochondrial genomes from the land snail Cornu aspersum were determined. The mitogenome has a length of 14050 bp, and it encodes 13 protein-coding genes, 22 transfer RNA genes and two ribosomal RNA genes. It also includes nine small intergene spacers, and a large AT-rich intergenic spacer. The intra-specific divergence analysis revealed that COX1 has the lower genetic differentiation, while the most divergent genes were NADH1, NADH3 and NADH4. With the exception of Euhadra herklotsi, the structural comparisons showed the same gene order within the family Helicidae, and nearly identical gene organization to that found in order Pulmonata. Phylogenetic reconstruction recovered Basommatophora as polyphyletic group, whereas Eupulmonata and Pulmonata as paraphyletic groups. Bayesian and Maximum Likelihood analyses showed that C. aspersum is a close relative of Cepaea nemoralis, and with the other Helicidae species form a sister group of Albinaria caerulea, supporting the monophyly of the Stylommatophora clade.
Highlights
Mitochondria, powerhouses of the cell, are in charge of producing energy in the form of Adenosine triphosphate (ATP) that is usable by the cell in eukaryotic organisms
Genome Structural Features The size of the mitochondrial genome of C. aspersum is 14050 bp (Fig. 2), and contains 13 protein-coding genes, 22 transfer RNA genes, and two ribosomal RNA genes (Fig. 2)
In agreement with our results it has been shown that the COX1 gene is one of the most conserved protein-coding genes in the mitochondrial genome of all metazoans [48,49], while the most variable are the subunits of the NADH oxidoreductase and ATP synthase complexes [50,51,52]
Summary
Mitochondria, powerhouses of the cell, are in charge of producing energy in the form of Adenosine triphosphate (ATP) that is usable by the cell in eukaryotic organisms. The mitochondrial genome of metazoans is typically a circular double stranded DNA molecule of about 12–20 kb length, which contains 37 genes including 13 protein-coding genes, 2 ribosomal RNAs (12S rRNA and 16S rRNA) genes, and 22 transfer RNAs (tRNAs) [3]. It has an AT-rich non-coding region that contains the potential origin for mitochondrial DNA replication (POR) [4] and RNA transcription (i.e., the mitochondrial control region) [3,5]. The monophyly of Eupulmonata (Fig. 1A) has been documented based on the combination of mitochondrial and nuclear genes [13,17,18], whereas the paraphyly of this group (Fig. 1B) has been recovered using complete mitochondrial genomes [4,16]
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