File Name: animal mitochondrial dna structure and evolution .zip
The mitochondrial genome is vital for Caenorhabditis elegans metabolism, physiology, and development. The C.
Replicating animal mitochondrial DNA. The field of mitochondrial DNA mtDNA replication has been experiencing incredible progress in recent years, and yet little is certain about the mechanism s used by animal cells to replicate this plasmid-like genome. Mutations in the genes coding for the first three proteins are associated with human diseases and premature aging, justifying the research interest in the genetic, biochemical and structural properties of the mtDNA replication machinery. Here we summarize these properties and discuss the current models of mtDNA replication in animal cells. For decades, the mitochondrial genome was thought to be a less important plasmid-like DNA, which contained residual genetic information from the ancestral a-proteobacterium that eventually became the mitochondrion, determining one of the most important endosymbiotic events in the evolutionary history of eukaryotes.
Dennis V. Animal mitochondrial DNA mtDNA is usually depicted as a small and very economically organized molecule with almost invariable gene content, stable gene order, a high rate of sequence evolution, and several unorthodox genetic features. Sampling across different animal phyla reveals that such a description applies primarily to mtDNA of bilaterian animals such as arthropods or chordates. By contrast, mitochondrial genomes of nonbilaterian animals phyla Cnidaria, Placozoa, and Porifera display more variation in size and gene content and, in most cases, lack the genetic novelties associated with bilaterian mtDNA. Outside the Metazoa, mtDNA of the choanoflagellate Monosiga brevicollis , the closest unicellular out-group, is a much larger molecule that contains a large proportion of noncoding DNA, 1. Thus, changes in animal mtDNA organization appear to correlate with two main transitions in animal evolution: the origin of multicellularity and the origin of the Bilateria.
We amplified and sequenced the mitochondrial control region from 23 species representing six families of teleost fish. The length of this segment is highly variable among even closely related species due to the presence of tandemly repeated sequences and large insertions. The position of the repetitive sequences suggests that they arise during replication both near the origin of replication and at the site of termination of the D-loop strand. Many of the conserved sequence blocks CSBs observed in mammals are also found among fish. In particular, the mammalian CSB-D is present in all of the fish species studied. Study of potential secondary structures of RNAs from the conserved regions provides little insight into the functional constraints on these regions. The variable structure of these control regions suggests that particular care should be taken to identify the most appropriate segment for studies of intraspecific variation.
This chapter describes structural features and evolution of metazoan mitochondrial DNA (mtDNA) molecules. Throughout the evolution of metazoa, gene content.
Volume 16 Issue 2 Mar. Turn off MathJax Article Contents. Zoological Research, , 16 2 :
Its role for the function of the cell and the organism remains a fertile field, its origin and evolution is an indispensable part of the evolution of life and its interaction with the nuclear DNA is among the most important cases of genome synergism and co-evolution. Also, mtDNA was proven one of the most useful tools in population genetics and molecular phylogenetics. In this article we focus on animal mtDNA and discuss briefly how our views about its structure, function and transmission have changed, how these changes affect the information we have accumulated through its use in the fields of phylogeny and population structure and what are the most important questions that remain open for future research. Mitochondria are organelles, remnants of ancestral bacterial endosymbionts, found in nearly all eukaryotic cells [ 1 ]. Mitochondria, along with plastids in plants, are the only cytoplasmic organelles in the eukaryotic cell that carry genetic elements.
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Accordingly, the endosymbiont hypothesis—the idea that the mitochondrion evolved from a bacterial progenitor via symbiosis within an essentially eukaryotic host cell—has assumed the status of a theory.Reply