scholarly journals Mitochondrial genomes of Columbicola feather lice are highly fragmented, indicating repeated evolution of minicircle-type genomes in parasitic lice

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e8759 ◽  
Author(s):  
Andrew D. Sweet ◽  
Kevin P. Johnson ◽  
Stephen L. Cameron
Keyword(s):  
Mitochondrial Genome ◽  
Sequence Data ◽  
Genome Structure ◽  
Mitochondrial Genomes ◽  
Single Chromosome ◽  
Pediculus Humanus ◽  
Feather Lice ◽  
Genome Shotgun Sequence ◽  
Repeated Evolution ◽  
Linear Chromosomes

Most animals have a conserved mitochondrial genome structure composed of a single chromosome. However, some organisms have their mitochondrial genes separated on several smaller circular or linear chromosomes. Highly fragmented circular chromosomes (“minicircles”) are especially prevalent in parasitic lice (Insecta: Phthiraptera), with 16 species known to have between nine and 20 mitochondrial minicircles per genome. All of these species belong to the same clade (mammalian lice), suggesting a single origin of drastic fragmentation. Nevertheless, other work indicates a lesser degree of fragmentation (2–3 chromosomes/genome) is present in some avian feather lice (Ischnocera: Philopteridae). In this study, we tested for minicircles in four species of the feather louse genus Columbicola (Philopteridae). Using whole genome shotgun sequence data, we applied three different bioinformatic approaches for assembling the Columbicola mitochondrial genome. We further confirmed these approaches by assembling the mitochondrial genome of Pediculus humanus from shotgun sequencing reads, a species known to have minicircles. Columbicola spp. genomes are highly fragmented into 15–17 minicircles between ∼1,100 and ∼3,100 bp in length, with 1–4 genes per minicircle. Subsequent annotation of the minicircles indicated that tRNA arrangements of minicircles varied substantially between species. These mitochondrial minicircles for species of Columbicola represent the first feather lice (Philopteridae) for which minicircles have been found in a full mitochondrial genome assembly. Combined with recent phylogenetic studies of parasitic lice, our results provide strong evidence that highly fragmented mitochondrial genomes, which are otherwise rare across the Tree of Life, evolved multiple times within parasitic lice.

scholarly journals Mitochondrial genomes ofColumbicolafeather lice are highly fragmented, indicating repeated evolution of minicircle-type genomes in parasitic lice

2019 ◽  
Author(s):  
Andrew D. Sweet ◽  
Kevin P. Johnson ◽  
Stephen L. Cameron
Keyword(s):  
Mitochondrial Genome ◽  
Sequence Data ◽  
Genome Structure ◽  
Mitochondrial Genomes ◽  
Single Chromosome ◽  
Pediculus Humanus ◽  
Feather Lice ◽  
Genome Shotgun Sequence ◽  
Repeated Evolution ◽  
Linear Chromosomes

ABSTRACTMost animals have a conserved mitochondrial genome structure composed of a single chromosome. However, some organisms have their mitochondrial genes separated on several smaller circular or linear chromosomes. Highly fragmented circular chromosomes (“minicircles”) are especially prevalent in parasitic lice (Insecta: Phthiraptera), with 16 species known to have between 9 and 20 mitochondrial minicircles per genome. All of these species belong to the same clade (mammalian lice), suggesting a single origin of drastic fragmentation. Nevertheless, other work indicates a lesser degree of fragmentation (2-3 chromosomes/genome) is present in some avian feather lice (Ischnocera: Philopteridae). In this study, we tested for minicircles in four species of the feather louse genusColumbicola(Philopteridae). Using whole genome shotgun sequence data, we applied three different bioinformatic approaches for assembling theColumbicolamitochondrial genome. We further confirmed these approaches by assembling the mitochondrial genome ofPediculus humanusfrom shotgun sequencing reads, a species known to have minicircles. All three methods indicatedColumbicolaspp. genomes are highly fragmented into 15-17 minicircles between 1,119 and 3,173 bp in length, with 1-4 genes per minicircle. Subsequent annotation of the minicircles indicated that tRNA arrangements of minicircles varied substantially between species. These mitochondrial minicircles for species ofColumbicolarepresent the first feather lice (Philopteridae) for which minicircles have been found in a full mitochondrial genome assembly. Combined with recent phylogenetic studies of parasitic lice, our results provide strong evidence that highly fragmented mitochondrial genomes, which are otherwise rare across the Tree of Life, evolved multiple times within parasitic lice.

scholarly journals Revealing the high variability on nonconserved core and mobile elements of Austropuccinia psidii and other rust mitochondrial genomes

PLoS ONE ◽  
2021 ◽  
Vol 16 (3) ◽  
pp. e0248054
Author(s):  
Jaqueline Raquel de Almeida ◽  
Diego Mauricio Riaño Pachón ◽  
Livia Maria Franceschini ◽  
Isaneli Batista dos Santos ◽  
Jessica Aparecida Ferrarezi ◽  
...  
Keyword(s):  
Mitochondrial Genome ◽  
Transmembrane Protein ◽  
Genome Structure ◽  
Rust Fungi ◽  
Mitochondrial Genomes ◽  
Phylogenomic Analysis ◽  
The Core ◽  
Mtdna Sequence ◽  
Austropuccinia Psidii

Mitochondrial genomes are highly conserved in many fungal groups, and they can help characterize the phylogenetic relationships and evolutionary biology of plant pathogenic fungi. Rust fungi are among the most devastating diseases for economically important crops around the world. Here, we report the complete sequence and annotation of the mitochondrial genome of Austropuccinia psidii (syn. Puccinia psidii), the causal agent of myrtle rust. We performed a phylogenomic analysis including the complete mitochondrial sequences from other rust fungi. The genome composed of 93.299 bp has 73 predicted genes, 33 of which encoded nonconserved proteins (ncORFs), representing almost 45% of all predicted genes. A. psidii mtDNA is one of the largest rust mtDNA sequenced to date, most likely due to the abundance of ncORFs. Among them, 33% were within intronic regions of diverse intron groups. Mobile genetic elements invading intron sequences may have played significant roles in size but not shaping of the rust mitochondrial genome structure. The mtDNAs from rust fungi are highly syntenic. Phylogenetic inferences with 14 concatenated mitochondrial proteins encoded by the core genes placed A. psidii according to phylogenetic analysis based on 18S rDNA. Interestingly, cox1, the gene with the greatest number of introns, provided phylogenies not congruent with the core set. For the first time, we identified the proteins encoded by three A. psidii ncORFs using proteomics analyses. Also, the orf208 encoded a transmembrane protein repressed during in vitro morphogenesis. To the best of our knowledge, we presented the first report of a complete mtDNA sequence of a member of the family Sphaerophragmiacea.

scholarly journals Largest Complete Mitochondrial Genome of a Gymnosperm, Sitka Spruce (Picea sitchensis), Indicates Complex Physical Structure

2019 ◽  
Author(s):  
Shaun D. Jackman ◽  
Lauren Coombe ◽  
René L. Warren ◽  
Heather Kirk ◽  
Eva Trinh ◽  
...  
Keyword(s):  
Mitochondrial Genome ◽  
Active Sites ◽  
Complete Mitochondrial Genome ◽  
Genome Structure ◽  
Sitka Spruce ◽  
Physical Structure ◽  
Picea Sitchensis ◽  
Mitochondrial Genomes ◽  
Long Reads ◽  
Branching Points

AbstractPlant mitochondrial genomes vary widely in size. Although many plant mitochondrial genomes have been sequenced and assembled, the vast majority are of angiosperms, and few are of gymnosperms. Most plant mitochondrial genomes are smaller than a megabase, with a few notable exceptions. We have sequenced and assembled the 5.5 Mbp mitochondrial genome of Sitka spruce (Picea sitchensis), the largest complete mitochondrial genome of a gymnosperm. We sequenced the whole genome using Oxford Nanopore MinION, and then identified contigs of mitochondrial origin assembled from these long reads. The assembly graph shows a multipartite genome structure, composed of one smaller 168 kbp circular segment of DNA, and a larger 5.4 Mbp component with a branching structure. The assembly graph gives insight into a putative complex physical genome structure, and its branching points may represent active sites of recombination.

scholarly journals Long-read sequencing reveals atypical mitochondrial genome structure in a New Zealand marine isopod

2022 ◽  
Vol 9 (1) ◽  
Author(s):  
William S. Pearman ◽  
Sarah J. Wells ◽  
James Dale ◽  
Olin K. Silander ◽  
Nikki E. Freed
Keyword(s):  
New Zealand ◽  
Mitochondrial Genome ◽  
Dna Sequencing ◽  
Recent Work ◽  
Genome Structure ◽  
Mitochondrial Genomes ◽  
Short Read ◽  
Mitochondrial Structure ◽  
Evolutionary Origins ◽  
Long Read

Most animal mitochondrial genomes are small, circular and structurally conserved. However, recent work indicates that diverse taxa possess unusual mitochondrial genomes. In Isopoda , species in multiple lineages have atypical and rearranged mitochondrial genomes. However, more species of this speciose taxon need to be evaluated to understand the evolutionary origins of atypical mitochondrial genomes in this group. In this study, we report the presence of an atypical mitochondrial structure in the New Zealand endemic marine isopod, Isocladus armatus. Data from long- and short-read DNA sequencing suggest that I. armatus has two mitochondrial chromosomes. The first chromosome consists of two mitochondrial genomes that have been inverted and fused together in a circular form, and the second chromosome consists of a single mitochondrial genome in a linearized form. This atypical mitochondrial structure has been detected in other isopod lineages, and our data from an additional divergent isopod lineage (Sphaeromatidae) lends support to the hypothesis that atypical structure evolved early in the evolution of Isopoda . Additionally, we find that an asymmetrical site previously observed across many species within Isopoda is absent in I. armatus , but confirm the presence of two asymmetrical sites recently reported in two other isopod species.

The plant mitochondrial genome: homologous recombination as a mechanism for generating heterogeneity

1988 ◽  
Vol 319 (1193) ◽  
pp. 149-163 ◽  
Keyword(s):  
Mitochondrial Dna ◽  
Homologous Recombination ◽  
Mitochondrial Genome ◽  
Higher Plants ◽  
Genome Structure ◽  
Rapid Evolution ◽  
Mitochondrial Genomes ◽  
Base Sequence ◽  
Plant Mitochondrial Genome ◽  
Organelle Genomes

The mitochondrial genomes of higher plants are among the largest and most complex organelle genomes described. They are generally multicircular or partly linear; in some species, extrachromosomal plasmids are present. It is proposed that inter- and intramolecular homologous recombination can account for the diversity of the observed genome organizations. The ability of mitochondria to fuse establishes a panmictic mitochondrial DNA population which is in recombinational equilibrium. It is suggested that this suppresses the base mutation rate, and unequal partitioning of the cytoplasm during cell division can lead to the rapid evolution of mitochondrial genome structure. This contrasts with the observed rates of base-sequence and genome evolution in chloroplasts. This difference can be accounted for solely by the inability of chloroplasts to fuse, thereby preventing chloroplast genome panmixis.

scholarly journals Comparison of the mitochondrial genomes of the Old and New World strains of the legume pod borer, Maruca vitrata (Lepidoptera: Crambidae)

2017 ◽  
Vol 37 (03) ◽  
pp. 125-136
Author(s):  
Tolulope A. Agunbiade ◽  
Brad S. Coates ◽  
Weilin Sun ◽  
Mu-Rou Tsai ◽  
Maria Carmen Valero ◽  
...  
Keyword(s):  
Mitochondrial Genome ◽  
New World ◽  
De Novo ◽  
Sequence Data ◽  
Complete Mitochondrial Genome ◽  
Maruca Vitrata ◽  
Mitochondrial Genomes ◽  
Old World ◽  
Pod Borer ◽  
Legume Pod Borer

Abstract Maruca vitrata (Fabricius, 1787) is a cryptic pantropical species of Lepidoptera that are comprised of two unique strains that inhabit the American continents (New World strain) and regions spanning from Africa through to Southeast Asia and Northern Australia (Old World strain). In this study, we de novo assembled the complete mitochondrial genome sequence of the New World legume pod borer, M. vitrata, from shotgun sequence data generated on an Illumina HiSeq 2000. Phylogenomic comparisons were made with other previously published mitochondrial genome sequences from crambid moths, including the Old World strain of M. vitrata. The 15,385 bp M. vitrata (New World) sequence has an 80.7% A+T content and encodes the 13 protein-coding, 2 ribosomal RNA and 22 transfer RNA genes in the typical orientation and arrangement of lepidopteran mitochondrial DNAs. Mitochondrial genome-wide comparison between the New and Old World strains of M. vitrata detected 476 polymorphic sites (4.23% nucleotide divergence) with an excess of synonymous substitution as a result of purifying selection. Furthermore, this level of sequence variation suggests that these strains diverged from ~1.83 to 2.12 million years ago, assuming a linear rate of short-term substitution. The de novo assemblies of mitochondrial genomes from next-generation sequencing (NGS) reads provide readily available data for similar comparative studies.

scholarly journals Complete mitochondrial genome sequences of the northern spotted owl (Strix occidentalis caurina) and the barred owl (Strix varia; Aves: Strigiformes: Strigidae) confirm the presence of a duplicated control region

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3901 ◽  
Author(s):  
Zachary R. Hanna ◽  
James B. Henderson ◽  
Anna B. Sellas ◽  
Jérôme Fuchs ◽  
Rauri C.K. Bowie ◽  
...  
Keyword(s):  
Mitochondrial Genome ◽  
Sequence Data ◽  
Complete Mitochondrial Genome ◽  
Mitochondrial Genes ◽  
Mitochondrial Genomes ◽  
Genome Sequences ◽  
Spotted Owl ◽  
Strix Occidentalis ◽  
Strix Occidentalis Caurina ◽  
Control Regions

We report here the successful assembly of the complete mitochondrial genomes of the northern spotted owl (Strix occidentalis caurina) and the barred owl (S. varia). We utilized sequence data from two sequencing methodologies, Illumina paired-end sequence data with insert lengths ranging from approximately 250 nucleotides (nt) to 9,600 nt and read lengths from 100–375 nt and Sanger-derived sequences. We employed multiple assemblers and alignment methods to generate the final assemblies. The circular genomes of S. o. caurina and S. varia are comprised of 19,948 nt and 18,975 nt, respectively. Both code for two rRNAs, twenty-two tRNAs, and thirteen polypeptides. They both have duplicated control region sequences with complex repeat structures. We were not able to assemble the control regions solely using Illumina paired-end sequence data. By fully spanning the control regions, Sanger-derived sequences enabled accurate and complete assembly of these mitochondrial genomes. These are the first complete mitochondrial genome sequences of owls (Aves: Strigiformes) possessing duplicated control regions. We searched the nuclear genome of S. o. caurina for copies of mitochondrial genes and found at least nine separate stretches of nuclear copies of gene sequences originating in the mitochondrial genome (Numts). The Numts ranged from 226–19,522 nt in length and included copies of all mitochondrial genes except tRNAPro, ND6, and tRNAGlu. Strix occidentalis caurina and S. varia exhibited an average of 10.74% (8.68% uncorrected p-distance) divergence across the non-tRNA mitochondrial genes.

scholarly journals Mitochondrial Genomic Landscape: A Portrait of the Mitochondrial Genome 40 Years after the First Complete Sequence

Life ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 663
Author(s):  
Alessandro Formaggioni ◽  
Andrea Luchetti ◽  
Federico Plazzi
Keyword(s):  
Mitochondrial Genome ◽  
Nucleotide Composition ◽  
Complete Sequence ◽  
Gene Content ◽  
Mitochondrial Genomes ◽  
Single Chromosome ◽  
Genomic Landscape ◽  
Linear Genomes ◽  
Huge Variation ◽  
General Conservation

Notwithstanding the initial claims of general conservation, mitochondrial genomes are a largely heterogeneous set of organellar chromosomes which displays a bewildering diversity in terms of structure, architecture, gene content, and functionality. The mitochondrial genome is typically described as a single chromosome, yet many examples of multipartite genomes have been found (for example, among sponges and diplonemeans); the mitochondrial genome is typically depicted as circular, yet many linear genomes are known (for example, among jellyfish, alveolates, and apicomplexans); the chromosome is normally said to be “small”, yet there is a huge variation between the smallest and the largest known genomes (found, for example, in ctenophores and vascular plants, respectively); even the gene content is highly unconserved, ranging from the 13 oxidative phosphorylation-related enzymatic subunits encoded by animal mitochondria to the wider set of mitochondrial genes found in jakobids. In the present paper, we compile and describe a large database of 27,873 mitochondrial genomes currently available in GenBank, encompassing the whole eukaryotic domain. We discuss the major features of mitochondrial molecular diversity, with special reference to nucleotide composition and compositional biases; moreover, the database is made publicly available for future analyses on the MoZoo Lab GitHub page.

scholarly journals Single-cell genomics unveils a canonical origin of the diverse mitochondrial genomes of euglenozoans

BMC Biology ◽  
2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Kristína Záhonová ◽  
Gordon Lax ◽  
Savar D. Sinha ◽  
Guy Leonard ◽  
Thomas A. Richards ◽  
...  
Keyword(s):  
Single Cell ◽  
Small Subunit ◽  
Rrna Genes ◽  
Mitochondrial Genomes ◽  
Trna Genes ◽  
Rrna Gene ◽  
Heterotrophic Flagellates ◽  
Small Subunit Rrna ◽  
Single Chromosome ◽  
Linear Chromosomes

Abstract Background The supergroup Euglenozoa unites heterotrophic flagellates from three major clades, kinetoplastids, diplonemids, and euglenids, each of which exhibits extremely divergent mitochondrial characteristics. Mitochondrial genomes (mtDNAs) of euglenids comprise multiple linear chromosomes carrying single genes, whereas mitochondrial chromosomes are circular non-catenated in diplonemids, but circular and catenated in kinetoplastids. In diplonemids and kinetoplastids, mitochondrial mRNAs require extensive and diverse editing and/or trans-splicing to produce mature transcripts. All known euglenozoan mtDNAs exhibit extremely short mitochondrial small (rns) and large (rnl) subunit rRNA genes, and absence of tRNA genes. How these features evolved from an ancestral bacteria-like circular mitochondrial genome remains unanswered. Results We sequenced and assembled 20 euglenozoan single-cell amplified genomes (SAGs). In our phylogenetic and phylogenomic analyses, three SAGs were placed within kinetoplastids, 14 within diplonemids, one (EU2) within euglenids, and two SAGs with nearly identical small subunit rRNA gene (18S) sequences (EU17/18) branched as either a basal lineage of euglenids, or as a sister to all euglenozoans. Near-complete mitochondrial genomes were identified in EU2 and EU17/18. Surprisingly, both EU2 and EU17/18 mitochondrial contigs contained multiple genes and one tRNA gene. Furthermore, EU17/18 mtDNA possessed several features unique among euglenozoans including full-length rns and rnl genes, six mitoribosomal genes, and nad11, all likely on a single chromosome. Conclusions Our data strongly suggest that EU17/18 is an early-branching euglenozoan with numerous ancestral mitochondrial features. Collectively these data contribute to untangling the early evolution of euglenozoan mitochondria.

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