Rapid Low-Cost Assembly of the Drosophila melanogaster Reference Genome Using Low-Coverage, Long-Read Sequencing

AbstractMotivationPopulation genomic analysis of transposable elements has greatly benefited from recent advances of sequencing technologies. However, the propensity of transposable elements to nest in highly repeated regions of genomes limits the efficiency of bioinformatic tools when short read sequences technology is used.ResultsLoRTE is the first tool able to use PacBio long read sequences to identify transposon deletions and insertions between a reference genome and genomes of different strains or populations. Tested against Drosophila melanogaster PacBio datasets, LoRTE appears to be a reliable and broadly applicable tools to study the dynamic and evolutionary impact of transposable elements using low coverage, long read sequences.Availability and ImplementationLoRTE is available at http://www.egce.cnrs-gif.fr/?p=6422. It is written in Python 2.7 and only requires the NCBI BLAST + package. LoRTE can be used on standard computer with limited RAM resources and reasonable running time even with large [email protected]

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Rapid low-cost assembly of the Drosophila melanogaster reference genome using low-coverage, long-read sequencing

10.1101/267401 ◽

2018 ◽

Cited By ~ 6

Author(s):

Edwin A. Solares ◽

Mahul Chakraborty ◽

Danny E. Miller ◽

Shannon Kalsow ◽

Kate Hall ◽

...

Keyword(s):

Drosophila Melanogaster ◽

Genetic Variation ◽

Large Scale ◽

Reference Genome ◽

De Novo ◽

Low Cost ◽

Nucleotide Polymorphisms ◽

Structural Variants ◽

High Coverage ◽

Reference Assembly

ABSTRACTAccurate and comprehensive characterization of genetic variation is essential for deciphering the genetic basis of diseases and other phenotypes. A vast amount of genetic variation stems from large-scale sequence changes arising from the duplication, deletion, inversion, and translocation of sequences. In the past 10 years, high-throughput short reads have greatly expanded our ability to assay sequence variation due to single nucleotide polymorphisms. However, a recent de novo assembly of a second Drosophila melanogaster reference genome has revealed that short read genotyping methods miss hundreds of structural variants, including those affecting phenotypes. While genomes assembled using high-coverage long reads can achieve high levels of contiguity and completeness, concerns about cost, errors, and low yield have limited widespread adoption of such sequencing approaches. Here we resequenced the reference strain of D. melanogaster (ISO1) on a single Oxford Nanopore MinION flow cell run for 24 hours. Using only reads longer than 1 kb or with at least 30x coverage, we assembled a highly contiguous de novo genome. The addition of inexpensive paired reads and subsequent scaffolding using an optical map technology achieved an assembly with completeness and contiguity comparable to the D. melanogaster reference assembly. Comparison of our assembly to the reference assembly of ISO1 uncovered a number of structural variants (SVs), including novel LTR transposable element insertions and duplications affecting genes with developmental, behavioral, and metabolic functions. Collectively, these SVs provide a snapshot of the dynamics of genome evolution. Furthermore, our assembly and comparison to the D. melanogaster reference genome demonstrates that high-quality de novo assembly of reference genomes and comprehensive variant discovery using such assemblies are now possible by a single lab for under $1,000 (USD).

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Identification of individual root-knot nematodes using low coverage long-read sequencing

PLoS ONE ◽

10.1371/journal.pone.0253248 ◽

2021 ◽

Vol 16 (12) ◽

pp. e0253248

Author(s):

Graham S. Sellers ◽

Daniel C. Jeffares ◽

Bex Lawson ◽

Tom Prior ◽

David H. Lunt

Keyword(s):

Plant Pathogens ◽

Low Cost ◽

Hybrid Origin ◽

Taxonomic Identification ◽

Taxonomic Assignment ◽

Root Knot Nematodes ◽

Marker Loci ◽

Long Read ◽

Low Coverage ◽

Individual Root

Root-knot nematodes (RKN; genus Meloidogyne) are polyphagous plant pathogens of great economic importance to agriculturalists globally. These species are small, diverse, and can be challenging for accurate taxonomic identification. Many of the most important crop pests confound analysis with simple genetic marker loci as they are polyploids of likely hybrid origin. Here we take a low-coverage, long-read genome sequencing approach to characterisation of individual root-knot nematodes. We demonstrate library preparation for Oxford Nanopore Technologies Flongle sequencing of low input DNA from individual juveniles and immature females, multiplexing up to twelve samples per flow cell. Taxonomic identification with Kraken 2 (a k-mer-based taxonomic assignment tool) is shown to reliably identify individual nematodes to species level, even within the very closely related Meloidogyne incognita group. Our approach forms a robust, low-cost, and scalable method for accurate RKN species diagnostics.

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Faculty Opinions recommendation of MinION-based long-read sequencing and assembly extends the Caenorhabditis elegans reference genome.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.732346961.793543720 ◽

2018 ◽

Author(s):

Charles Baer

Keyword(s):

Caenorhabditis Elegans ◽

Reference Genome ◽

Long Read

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Long-read assembly and comparative evidence-based reanalysis of Cryptosporidium genome sequences reveals expanded transporter repertoire and duplication of entire chromosome ends including subtelomeric regions

Genome Research ◽

10.1101/gr.275325.121 ◽

2021 ◽

pp. gr.275325.121

Author(s):

Rodrigo P. Baptista ◽

Yiran Li ◽

Adam Sateriale ◽

Karen L. Brooks ◽

Alan Tracey ◽

...

Keyword(s):

Genome Assembly ◽

Reference Genome ◽

Diarrheal Disease ◽

Gene Copy ◽

Future Research ◽

Single Nucleotide Variants ◽

Cryptosporidium Hominis ◽

Entire Chromosome ◽

Long Read ◽

Subtelomeric Regions

Cryptosporidiosis is a leading cause of waterborne diarrheal disease globally and an important contributor to mortality in infants and the immunosuppressed. Despite its importance, the Cryptosporidium community has only had access to a good, but incomplete, Cryptosporidium parvum IOWA reference genome sequence. Incomplete reference sequences hamper annotation, experimental design and interpretation. We have generated a new C. parvum IOWA genome assembly supported by PacBio and Oxford Nanopore long-read technologies and a new comparative and consistent genome annotation for three closely related species C. parvum, Cryptosporidium hominis and Cryptosporidium tyzzeri. We made 1,926 C. parvum annotation updates based on experimental evidence. They include new transporters, ncRNAs, introns and altered gene structures. The new assembly and annotation revealed a complete Dnmt2 methylase ortholog. Comparative annotation between C. parvum, C. hominis and C. tyzzeri revealed that most "missing" orthologs are found suggesting that the biological differences between the species must result from gene copy number variation, differences in gene regulation and single nucleotide variants (SNVs). Using the new assembly and annotation as reference, 190 genes are identified as evolving under positive selection, including many not detected previously. The new C. parvum IOWA reference genome assembly is larger, gap free and lacks ambiguous bases. This chromosomal assembly recovers all 16 chromosome ends, 13 of which are contiguously assembled. The three remaining chromosome ends are provisionally placed. These ends represent duplication of entire chromosome ends including subtelomeric regions revealing a new level of genome plasticity that will both inform and impact future research.

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DNA Preparation In Vitis Vinifera L. for Third Generation Sequencing

10.21203/rs.3.rs-259540/v2 ◽

2021 ◽

Author(s):

Androniki C. Bibi ◽

Anastasios Kollias ◽

Maria Astrinaki ◽

Despoina Vassou ◽

Dimitris Kafetzopoulos ◽

...

Keyword(s):

Vitis Vinifera ◽

Low Cost ◽

Ease Of Use ◽

Vitis Vinifera L ◽

Full Potential ◽

Third Generation ◽

High Quality ◽

Fresh Tissue ◽

Long Read ◽

Young Leaves

Abstract Background: There have been several attempts to sequence the genome of Vitis vinifera L. (grapevine), utilizing low-resolution second-generation platforms. Nevertheless, the characterization of the grapevine genetic resources and its adaptation to vulnerable conditions could be better addressed through extensive and high-resolution genome sequencing.MinION is a third-generation sequencer preferred by many laboratories due to its relatively low cost, ease of use and small size. Even though this long-read technology has been rapidly improving, to reach its full potential requires high-quality DNA.Results: Here we establish a workflow for DNA extraction suitable for MinION sequencing long reads from grapevine. This protocol was tested with leaf samples from different positions on annual growing branches of grapevine, Purified nuclei from fresh young leaves that led to high quality, long DNA fragments, suitable for long-read sequencing were successfully generated. It is evident that longer reads in grapevine associate with both fresh tissue and adjusted conditions used for nuclei purification.Conclusions: We propose that this workflow presents a significant advancement for long-read quality DNA isolation for grapevine and likely other plant species.

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Rapture-ready darters: choice of reference genome and genotyping method (whole-genome or sequence capture) influence population genomic inference in Etheostoma

10.1101/2020.05.21.108274 ◽

2020 ◽

Author(s):

Brendan N. Reid ◽

Rachel L. Moran ◽

Christopher J. Kopack ◽

Sarah W. Fitzpatrick

Keyword(s):

Reference Genome ◽

Sequence Data ◽

Low Cost ◽

Read Depth ◽

Model Organisms ◽

Whole Genome ◽

Reduced Representation ◽

Sequence Capture ◽

Population Genomic ◽

The Impact

AbstractResearchers studying non-model organisms have an increasing number of methods available for generating genomic data. However, the applicability of different methods across species, as well as the effect of reference genome choice on population genomic inference, are still difficult to predict in many cases. We evaluated the impact of data type (whole-genome vs. reduced representation) and reference genome choice on data quality and on population genomic and phylogenomic inference across several species of darters (subfamily Etheostomatinae), a highly diverse radiation of freshwater fish. We generated a high-quality reference genome and developed a hybrid RADseq/sequence capture (Rapture) protocol for the Arkansas darter (Etheostoma cragini). Rapture data from 1900 individuals spanning four darter species showed recovery of most loci across darter species at high depth and consistent estimates of heterozygosity regardless of reference genome choice. Loci with baits spanning both sides of the restriction enzyme cut site performed especially well across species. For low-coverage whole-genome data, choice of reference genome affected read depth and inferred heterozygosity. For similar amounts of sequence data, Rapture performed better at identifying fine-scale genetic structure compared to whole-genome sequencing. Rapture loci also recovered an accurate phylogeny for the study species and demonstrated high phylogenetic informativeness across the evolutionary history of the genus Etheostoma. Low cost and high cross-species effectiveness regardless of reference genome suggest that Rapture and similar sequence capture methods may be worthwhile choices for studies of diverse species radiations.

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Constructing a Reference Genome in a Single Lab: The Possibility to Use Oxford Nanopore Technology

Plants ◽

10.3390/plants8080270 ◽

2019 ◽

Vol 8 (8) ◽

pp. 270 ◽

Cited By ~ 4

Author(s):

Yun Gyeong Lee ◽

Sang Chul Choi ◽

Yuna Kang ◽

Kyeong Min Kim ◽

Chon-Sik Kang ◽

...

Keyword(s):

Plant Species ◽

Genome Sequencing ◽

Reference Genome ◽

Genome Structure ◽

Plant Genome ◽

Sequence Information ◽

Sequencing Analysis ◽

Oxford Nanopore ◽

A Genome ◽

Long Read

The whole genome sequencing (WGS) has become a crucial tool in understanding genome structure and genetic variation. The MinION sequencing of Oxford Nanopore Technologies (ONT) is an excellent approach for performing WGS and it has advantages in comparison with other Next-Generation Sequencing (NGS): It is relatively inexpensive, portable, has simple library preparation, can be monitored in real-time, and has no theoretical limits on reading length. Sorghum bicolor (L.) Moench is diploid (2n = 2x = 20) with a genome size of about 730 Mb, and its genome sequence information is released in the Phytozome database. Therefore, sorghum can be used as a good reference. However, plant species have complex and large genomes when compared to animals or microorganisms. As a result, complete genome sequencing is difficult for plant species. MinION sequencing that produces long-reads can be an excellent tool for overcoming the weak assembly of short-reads generated from NGS by minimizing the generation of gaps or covering the repetitive sequence that appears on the plant genome. Here, we conducted the genome sequencing for S. bicolor cv. BTx623 while using the MinION platform and obtained 895,678 reads and 17.9 gigabytes (Gb) (ca. 25× coverage of reference) from long-read sequence data. A total of 6124 contigs (covering 45.9%) were generated from Canu, and a total of 2661 contigs (covering 50%) were generated from Minimap and Miniasm with a Racon through a de novo assembly using two different tools and mapped assembled contigs against the sorghum reference genome. Our results provide an optimal series of long-read sequencing analysis for plant species while using the MinION platform and a clue to determine the total sequencing scale for optimal coverage that is based on various genome sizes.

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Assessment of Imputation from Low-Pass Sequencing to Predict Merit of Beef Steers

Genes ◽

10.3390/genes11111312 ◽

2020 ◽

Vol 11 (11) ◽

pp. 1312

Author(s):

Warren M. Snelling ◽

Jesse L. Hoff ◽

Jeremiah H. Li ◽

Larry A. Kuehn ◽

Brittney N. Keel ◽

...

Keyword(s):

Genomic Prediction ◽

Genomic Sequence ◽

Bos Taurus ◽

Low Cost ◽

Bos Indicus ◽

Snp Array ◽

Attractive Alternative ◽

Functional Variant ◽

Low Pass ◽

Low Coverage

Decreasing costs are making low coverage sequencing with imputation to a comprehensive reference panel an attractive alternative to obtain functional variant genotypes that can increase the accuracy of genomic prediction. To assess the potential of low-pass sequencing, genomic sequence of 77 steers sequenced to >10X coverage was downsampled to 1X and imputed to a reference of 946 cattle representing multiple Bos taurus and Bos indicus-influenced breeds. Genotypes for nearly 60 million variants detected in the reference were imputed from the downsampled sequence. The imputed genotypes strongly agreed with the SNP array genotypes (r¯=0.99) and the genotypes called from the transcript sequence (r¯=0.97). Effects of BovineSNP50 and GGP-F250 variants on birth weight, postweaning gain, and marbling were solved without the steers’ phenotypes and genotypes, then applied to their genotypes, to predict the molecular breeding values (MBV). The steers’ MBV were similar when using imputed and array genotypes. Replacing array variants with functional sequence variants might allow more robust MBV. Imputation from low coverage sequence offers a viable, low-cost approach to obtain functional variant genotypes that could improve genomic prediction.

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Closing Human Reference Genome Gaps: Identifying and Characterizing Gap-Closing Sequences

G3 Genes|Genome|Genetics ◽

10.1534/g3.120.401280 ◽

2020 ◽

Vol 10 (8) ◽

pp. 2801-2809 ◽

Cited By ~ 1

Author(s):

Tingting Zhao ◽

Zhongqu Duan ◽

Georgi Z. Genchev ◽

Hui Lu

Keyword(s):

Reference Genome ◽

De Novo ◽

Sequence Length ◽

Sequencing Data ◽

Human Reference Genome ◽

Satellite Sequences ◽

Long Read ◽

Data Gap ◽

Simple Repeats ◽

Gap Closing

Despite continuous updates of the human reference genome, there are still hundreds of unresolved gaps which account for about 5% of the total sequence length. Given the availability of whole genome de novo assemblies, especially those derived from long-read sequencing data, gap-closing sequences can be determined. By comparing 17 de novo long-read sequencing assemblies with the human reference genome, we identified a total of 1,125 gap-closing sequences for 132 (16.9% of 783) gaps and added up to 2.2 Mb novel sequences to the human reference genome. More than 90% of the non-redundant sequences could be verified by unmapped reads from the Simons Genome Diversity Project dataset. In addition, 15.6% of the non-reference sequences were found in at least one of four non-human primate genomes. We further demonstrated that the non-redundant sequences had high content of simple repeats and satellite sequences. Moreover, 43 (32.6%) of the 132 closed gaps were shown to be polymorphic; such sequences may play an important biological role and can be useful in the investigation of human genetic diversity.

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