Two reads to rule them all: Nanopore long read-guided assembly of the iconic Christmas Island red crab, Gecarcoidea natalis (Pocock, 1888), mitochondrial genome and the challenges of AT-rich mitogenomes

2019 ◽  
Vol 45 ◽  
pp. 64-71 ◽  
Author(s):  
Han Ming Gan ◽  
Stuart M. Linton ◽  
Christopher M. Austin
Keyword(s):  
Mitochondrial Genome ◽  
Christmas Island ◽  
Long Read ◽  
Guided Assembly ◽  
Gecarcoidea Natalis

scholarly journals Mitochondrial genome evolution in pelagophyte algae

2021 ◽  
Author(s):  
Shannon J Sibbald ◽  
Maggie Lawton ◽  
John M Archibald
Keyword(s):  
Mitochondrial Genome ◽  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
23S Rrna ◽  
Mitochondrial Genomes ◽  
Trna Genes ◽  
Unique Region ◽  
Long Read ◽  
Genomic Studies ◽  
Aureoumbra Lagunensis

Abstract The Pelagophyceae are marine stramenopile algae that include Aureoumbra lagunensis and Aureococcus anophagefferens, two microbial species notorious for causing harmful algal blooms. Despite their ecological significance, relatively few genomic studies of pelagophytes have been carried out. To improve understanding of the biology and evolution of pelagophyte algae, we sequenced complete mitochondrial genomes for A. lagunensis (CCMP1510), Pelagomonas calceolata (CCMP1756) and five strains of A. anophagefferens (CCMP1707, CCMP1708, CCMP1850, CCMP1984 and CCMP3368) using Nanopore long-read sequencing. All pelagophyte mitochondrial genomes assembled into single, circular mapping contigs between 39,376 base-pairs (bp) (P. calceolata) and 55,968 bp (A. lagunensis) in size. Mitochondrial genomes for the five A. anophagefferens strains varied slightly in length (42,401 bp—42,621 bp) and were 99.4%-100.0% identical. Gene content and order was highly conserved between the A. anophagefferens and P. calceolata genomes, with the only major difference being a unique region in A. anophagefferens containing DNA adenine and cytosine methyltransferase (dam/dcm) genes that appear to be the product of lateral gene transfer from a prokaryotic or viral donor. While the A. lagunensis mitochondrial genome shares seven distinct syntenic blocks with the other pelagophyte genomes, it has a tandem repeat expansion comprising ∼40% of its length, and lacks identifiable rps19 and glycine tRNA genes. Laterally acquired self-splicing introns were also found in the 23S rRNA (rnl) gene of P. calceolata and the coxI gene of the five A. anophagefferens genomes. Overall, these data provide baseline knowledge about the genetic diversity of bloom-forming pelagophytes relative to non-bloom-forming species.

EXERCISE IN THE TERRESTRIAL CHRISTMAS ISLAND RED CRAB GECARCOIDEA NATALIS - BLOOD GAS TRANSPORT

1994 ◽  
Vol 188 (1) ◽  
pp. 235-256 ◽  
Author(s):  
A Adamczewska ◽  
S Morris
Keyword(s):  
Gas Transport ◽  
Lactate Production ◽  
Circulatory System ◽  
Indirect Evidence ◽  
Blood Gas ◽  
Christmas Island ◽  
Exercise Period ◽  
Gas Measurements ◽  
Gecarcoidea Natalis ◽  
O2 Delivery

The respiratory and circulatory physiology of the terrestrial Christmas Island red crab Gecarcoidea natalis was investigated with respect to exercise in the context of its annual breeding migration. Red crabs were allowed to walk for predetermined periods of up to 45 min. During this exercise period, blood gas measurements were made on venous, pulmonary and arterial samples to assess the function of the lungs in gas exchange and the performance of the circulatory system in gas transport and to determine the role and importance of the haemocyanin. The lungs of G. natalis were very efficient at O2 uptake, pulmonary blood being 80­90 % saturated throughout the 45 min exercise period. The maximum O2-carrying capacity was 1.1 mmol l-1, and haemocyanin (Hc) delivered 86 % of oxygen in resting crabs and 97 % during exercise. Oxygen delivery to the tissues was diffusion-limited during exercise. Indirect evidence, from the changes in haemolymph pH during transit through the lungs, suggested that the lung is the site of CO2 excretion. The Bohr shift was high at high pH (pH 7.8­7.5, phi=-1.23) but decreased at low pH (pH 7.1­6.8, phi=-0.48). The decreased Hc affinity for O2 during the exercise period facilitated O2 delivery to the tissues without impairing O2 loading at the lungs. The decrease in pH was sufficient to explain the change of affinity of Hc for O2 during the exercise period. The marked acidosis (0.8 pH unit decrease) was largely metabolic in origin, especially during sustained locomotion, but less than could be predicted from concomitant lactate production.

scholarly journals Long-read assemblies reveal structural diversity in genomes of organelles - an example with Acacia pycnantha

2020 ◽  
Author(s):  
Anna E. Syme ◽  
Todd G.B. McLay ◽  
Frank Udovicic ◽  
David J. Cantrill ◽  
Daniel J. Murphy
Keyword(s):  
Mitochondrial Genome ◽  
Chloroplast Genome ◽  
De Novo ◽  
Genomic Structure ◽  
Structural Diversity ◽  
Mitochondrial Genomes ◽  
Long Reads ◽  
Organelle Genomes ◽  
Long Read ◽  
Assembly Algorithms

AbstractAlthough organelle genomes are typically represented as single, static, circular molecules, there is evidence that the chloroplast genome exists in two structural haplotypes and that the mitochondrial genome can display multiple circular, linear or branching forms. We sequenced and assembled chloroplast and mitochondrial genomes of the Golden Wattle, Acacia pycnantha, using long reads, iterative baiting to extract organelle-only reads, and several assembly algorithms to explore genomic structure. Using a de novo assembly approach agnostic to previous hypotheses about structure, we found different assemblies revealed contrasting arrangements of genomic segments; a hypothesis supported by mapped reads spanning alternate paths.

scholarly journals The complete mitochondrial genome sequence of Oryctes rhinoceros (Coleoptera: Scarabaeidae) based on long-read nanopore sequencing

2020 ◽  
Author(s):  
Igor Filipović ◽  
James P. Hereward ◽  
Gordana Rašić ◽  
Gregor J. Devine ◽  
Michael J. Furlong ◽  
...  
Keyword(s):  
Mitochondrial Genome ◽  
Control Region ◽  
Complete Mitochondrial Genome ◽  
Rrna Genes ◽  
Invasive Pest ◽  
Long Control Region ◽  
Trna Genes ◽  
Oryctes Rhinoceros ◽  
Mitogenome Sequence ◽  
Long Read

AbstractThe coconut rhinoceros beetle (CRB, Oryctes rhinoceros) is a severe and invasive pest of coconut and other palms throughout Asia and the Pacific. The biocontrol agent, Oryctes rhinoceros nudivirus (OrNV), has successfully suppressed O. rhinoceros populations for decades but new CRB invasions started appearing after 2007. A single-SNP variant within the mitochondrial cox1 gene is used to distinguish the recently-invading CRB-G lineage from other haplotypes, but the lack of mitogenome sequence for this species hinders further development of a molecular toolset for biosecurity and management programmes against CRB. Here we report the complete circular sequence and annotation for CRB mitogenome, generated to support such efforts.Sequencing data were generated using long-read Nanopore technology from genomic DNA isolated from a CRB-G female. The mitochondrial genome was assembled with Flye v.2.5, using the short-read Illumina sequences to remove homopolymers with Pilon, and annotated with MITOS. Independently-generated transcriptome data were used to assess the O. rhinoceros mitogenome annotation and transcription. The aligned sequences of 13 protein-coding genes (PCGs) (with degenerate third codon position) from O. rhinoceros, 13 other Scarabaeidae taxa and two outgroup taxa were used for the phylogenetic reconstruction with the Maximum likelihood (ML) approach in IQ-TREE and Bayesian (BI) approach in MrBayes.The complete circular mitochondrial genome of O. rhinoceros is 20,898 bp-long, with a gene content canonical for insects (13 PCGs, 2 rRNA genes, and 22 tRNA genes), as well as one structural variation (rearrangement of trnQ and trnI) and a long control region (6,204 bp). Transcription was detected across all 37 genes, and interestingly, within three domains in the control region. ML and BI phylogenies had the same topology, correctly grouping O. rhinoceros with one other Dynastinae taxon, and recovering the previously reported relationship among lineages in the Scarabaeidae. In silico PCR-RFLP analysis recovered the correct fragment set that is diagnostic for the CRB-G haplogroup. These results validate the high-quality of the CRB mitogenome sequence and annotation.

scholarly journals Strategies and difficulties in assembling highly recombinogenic plant organelle genomes: a case study

2015 ◽  
Author(s):  
Concita Cantarella ◽  
Rachele Tamburino ◽  
Nunzia Scotti ◽  
Teodoro Cardi ◽  
Nunzio D'Agostino
Keyword(s):  
Mitochondrial Dna ◽  
Mitochondrial Genome ◽  
De Novo ◽  
Sequence Data ◽  
Repeated Sequences ◽  
Read Length ◽  
Plant Mitochondrial Genome ◽  
Sequencing Platform ◽  
Organelle Genomes ◽  
Long Read

Mitochondrial genomes in plants are larger and more complex than in other eukaryotes due to their recombinogenic nature as widely demonstrated. The mitochondrial DNA (mtDNA) is usually represented as a single circular map, the so-called master molecule. This molecule includes repeated sequences, some of which are able to recombine, generating sub-genomic molecules in various amounts, depending on the balance between their recombination and replication rates. Recent advances in DNA sequencing technology gave a huge boost to plant mitochondrial genome projects. Conventional approaches to mitochondrial genome sequencing involve extraction and enrichment of mitochondrial DNA, cloning, and sequencing. Large repeats and the dynamic mitochondrial genome organization complicate de novo sequence assembly from short reads. The PacBio RS long-read sequencing platform offers the promise of increased read length and unbiased genome coverage and thus the potential to produce genome sequence data of a finished quality (fewer gaps and longer contigs). However, recently published articles revealed that PacBio sequencing is still not sufficient to address mtDNA assembly-related issues. Here we present a preliminary hybrid assembly of a potato mtDNA based on both PacBio and Illumina reads and debate the strategies and obstacles in assembling genomes containing repeated sequences that are recombinationally active and serve as a constant source of rearrangements.

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.

scholarly journals Mitochondrial sequences or Numts – By-catch differs between sequencing methods

2019 ◽  
Author(s):  
Hannes Becher ◽  
Richard A Nichols
Keyword(s):  
Mitochondrial Dna ◽  
Mitochondrial Genome ◽  
Nuclear Genome ◽  
Short Read ◽  
Ancestral Sequences ◽  
Mtdna Sequence ◽  
Long Read ◽  
Data Yield ◽  
By Catch ◽  
Numt Sequence

AbstractNuclear inserts derived from mitochondrial DNA (Numts) encode valuable information. Being mostly non-functional, and accumulating mutations more slowly than mitochondrial sequence, they act like molecular fossils – they preserve information on the ancestral sequences of the mitochondrial DNA. In addition, changes to the Numt sequence since their insertion into the nuclear genome carry information about the nuclear phylogeny. These attributes cannot be reliably exploited if Numt sequence is confused with the mitochondrial genome (mtDNA). The analysis of mtDNA would be similarly compromised by any confusion, for example producing misleading results in DNA barcoding that used mtDNA sequence. We propose a method to distinguish Numts from mtDNA, without the need for comprehensive assembly of the nuclear genome or the physical separation of organelles and nuclei. It exploits the different biases of long and short-read sequencing. We find that short-read data yield mainly mtDNA sequences, whereas long-read sequencing strongly enriches for Numt sequences. We demonstrate the method using genome-skimming (coverage < 1x) data obtained on Illumina short-read and PacBio long-read technology from DNA extracted from six grasshopper individuals. The mitochondrial genome sequences were assembled from the short-read data despite the presence of Numts. The PacBio data contained a much higher proportion of Numt reads (over 16-fold), making us caution against the use of long-read methods for studies using mitochondrial loci. We obtained two estimates of the genomic proportion of Numts. Finally, we introduce “tangle plots”, a way of visualising Numt structural rearrangements and comparing them between samples.

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