Itcontains the 37 genes that are typical for animal mtDNAs, with 15 on oneDNA strand and 22 on the other. Results: The mitochondrial genome of a cephalopodmollusk, the Chambered Nautilus, is 16,258 nts in length and 59.5 percentA+T, both values that are typical of animal mitochondrial genomes.
Their comparison serves as amodel system for understanding the processes of genome evolution.Although complete mitochondrial genome sequences have been reported formore than 600 animals, the taxonomic sampling is highly biased towardvertebrates and arthropods, leaving much of the diversity yetuncharacterized. « lessīackground: Mitochondria contain small genomes that arephysically separate from those of nuclei. This appears to be yet another case where polyadenylation of mitochondrial tRNAs restores what would otherwise be an incomplete structure. tunicata implies that mutational bias during replication also plays a role. The skew in nucleotide composition between the two strands is strong and associated with the direction of transcription in various parts of the genomes, but a comparison with K. It contains an unusual number of non-coding regions, especially considering that these otherwise often are generated by the same processes that produce gene rearrangements. Conclusion: Nautilus macromphalus mtDNA contains an expected gene content that has experienced few rearrangements since the evolutionary split between cephalopods and polyplacophorans. Some of the tRNA genes appear to overlap on the same strand, but this could be resolved if the polycistron were cleaved at the beginning of the downstream gene, followed by polyadenylation of the product of the upstream gene to form a fully paired structure.
One of the non-coding regions contains multiple repeats of a tRNA-like sequence. There is an unusual number of non-coding regions and their function, if any, is not known however, several of these demark abrupt shifts in nucleotide skew, and there are several identical sequence elements at these junctions, suggesting that they may play roles in transcription and/or replication. There is strong skew in the distribution of nucleotides between the two strands, and analysis of this yields insight into modes of transcription and replication. The arrangement of these genes can be derived from that of the distantly related Katharina tunicata (Mollusca: Polyplacophora) by a switch in position of two large blocks of genes and transpositions of four tRNA genes. It contains the 37 genes that are almost universally found in animal mtDNAs, more » with 15 on one DNA strand and 22 on the other. Results: The mitochondrial genome of the bellybutton nautilus, Nautilus macromphalus, a cephalopod mollusk, is 16,258 nts in length and 59.5% A+T, both values that are typical of animal mitochondrial genomes. Although complete mitochondrial genome sequences have been reported for more than 600 animals, the taxonomic sampling is highly biased toward vertebrates and arthropods, leaving much of the diversity yet uncharacterized. Their comparison serves as a model system for understanding the processes of genome evolution. = ,īackground: Mitochondria contain small genomes that are physically separate from those of nuclei.
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