De novo assembly of a chromosome-scale reference genome for the northern flicker Colaptes auratus.
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ABSTRACT:
SUBMITTER: Hruska JP
PROVIDER: S-EPMC8022726 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:BackgroundThe Syrian hamster (Mesocricetus auratus) has been suggested as a useful mammalian model for a variety of diseases and infections, including infection with respiratory viruses such as SARS-CoV-2. The MesAur1.0 genome assembly was generated in 2013 using whole-genome shotgun sequencing with short-read sequence data. Current more advanced sequencing technologies and assembly methods now permit the generation of near-complete genome assemblies with higher quality and greater continuity.FindingsHere, we report an improved assembly of the M. auratus genome (BCM_Maur_2.0) using Oxford Nanopore Technologies long-read sequencing to produce a chromosome-scale assembly. The total length of the new assembly is 2.46 Gb, similar to the 2.50-Gb length of a previous assembly of this genome, MesAur1.0. BCM_Maur_2.0 exhibits significantly improved continuity, with a scaffold N50 that is 6.7 times greater than MesAur1.0. Furthermore, 21,616 protein-coding genes and 10,459 noncoding genes are annotated in BCM_Maur_2.0 compared to 20,495 protein-coding genes and 4,168 noncoding genes in MesAur1.0. This new assembly also improves the unresolved regions as measured by nucleotide ambiguities, where ∼17.11% of bases in MesAur1.0 were unresolved compared to BCM_Maur_2.0, in which the number of unresolved bases is reduced to 3.00%.ConclusionsAccess to a more complete reference genome with improved accuracy and continuity will facilitate more detailed, comprehensive, and meaningful research results for a wide variety of future studies using Syrian hamsters as models.
| S-EPMC9155146 | biostudies-literature
Project description:MotivationThere are very few methods for de novo genome assembly based on the overlap graph approach. It is considered as giving more exact results than the so-called de Bruijn graph approach but in much greater time and of much higher memory usage. It is not uncommon that assembly methods involving the overlap graph model are not able to successfully compute greater datasets, mainly due to memory limitation of a computer. This was the reason for developing in last decades mainly de Bruijn-based assembly methods, fast and fairly accurate. However, the latter methods can fail for longer or more repetitive genomes, as they decompose reads to shorter fragments and lose a part of information. An efficient assembler for processing big datasets and using the overlap graph model is still looked out.ResultsWe propose a new genome-scale de novo assembler based on the overlap graph approach, designed for short-read sequencing data. The method, ALGA, incorporates several new ideas resulting in more exact contigs produced in short time. Among these ideas, we have creation of a sparse but quite informative graph, reduction of the graph including a procedure referring to the problem of minimum spanning tree of a local subgraph, and graph traversal connected with simultaneous analysis of contigs stored so far. What is rare in genome assembly, the algorithm is almost parameter-free, with only one optional parameter to be set by a user. ALGA was compared with nine state-of-the-art assemblers in tests on genome-scale sequencing data obtained from real experiments on six organisms, differing in size, coverage, GC content and repetition rate. ALGA produced best results in the sense of overall quality of genome reconstruction, understood as a good balance between genome coverage, accuracy and length of resulting sequences. The algorithm is one of tools involved in processing data in currently realized national project Genomic Map of Poland.Availability and implementationALGA is available at http://alga.put.poznan.pl.Supplementary informationSupplementary data are available at Bioinformatics online.
| S-EPMC8289375 | biostudies-literature
Project description:We announce the assembly of the first de novo reference genome for the California Scrub-Jay (Aphelocoma californica). The genus Aphelocoma comprises four currently recognized species including many locally adapted populations across Mesoamerica and North America. Intensive study of Aphelocoma has revealed novel insights into the evolutionary mechanisms driving diversification in natural systems. Additional insights into the evolutionary history of this group will require continued development of high-quality, publicly available genomic resources. We extracted high molecular weight genomic DNA from a female California Scrub-Jay from northern California and generated PacBio HiFi long-read data and Omni-C chromatin conformation capture data. We used these data to generate a de novo partially phased diploid genome assembly, consisting of two pseudo-haplotypes, and scaffolded them using inferred physical proximity information from the Omni-C data. The more complete pseudo-haplotype assembly (arbitrarily designated "Haplotype 1") is 1.35 Gb in total length, highly contiguous (contig N50 = 11.53 Mb), and highly complete (BUSCO completeness score = 97%), with comparable scaffold sizes to chromosome-level avian reference genomes (scaffold N50 = 66.14 Mb). Our California Scrub-Jay assembly is highly syntenic with the New Caledonian Crow reference genome despite ~10 million years of divergence, highlighting the temporal stability of the avian genome. This high-quality reference genome represents a leap forward in publicly available genomic resources for Aphelocoma, and the family Corvidae more broadly. Future work using Aphelocoma as a model for understanding the evolutionary forces generating and maintaining biodiversity across phylogenetic scales can now benefit from a highly contiguous, in-group reference genome.
| S-EPMC10650945 | biostudies-literature
Project description:IntroductionLablab (Lablab purpureus (L.) Sweet), an underutilized tropical legume crop, plays a crucial role in global food and nutritional security. To enhance our understanding of its genetic makeup towards developing elite cultivars, we sequenced and assembled a draft genome of L. purpureus accession PK2022T020 using a single tube long fragment read (stLFR) technique.Results and discussionThe preliminary assembly encompassed 367 Mb with a scaffold N50 of 4.3 Mb. To improve the contiguity of our draft genome, we employed a chromatin contact mapping (Hi-C) approach to obtain a pseudochromosome-level assembly containing 366 Mb with an N50 length of 31.1 Mb. A total of 327.4 Mb had successfully been anchored into 11 pseudomolecules, corresponding to the haploid chromosome number in lablab. Our gene prediction recovered 98.4% of the highly conserved orthologs based on the Benchmarking Universal Single-Copy Orthologs (BUSCO) analysis. Comparative analyses utilizing sequence information from single-copy orthologous genes demonstrated that L. purpureus diverged from the last common ancestor of the Phaseolus/Vigna species approximately 27.7 million years ago. A gene family expansion analysis revealed a significant expansion of genes involved in responses to biotic and abiotic stresses. Our high-quality chromosome-scale reference assembly provides an invaluable genomic resource for lablab genetic improvement and future comparative genomics studies among legume species.
| S-EPMC10948561 | biostudies-literature
Project description:The development of next-generation sequencing has made it possible to sequence whole genomes at a relatively low cost. However, de novo genome assemblies remain challenging due to short read length, missing data, repetitive regions, polymorphisms and sequencing errors. As more and more genomes are sequenced, reference-guided assembly approaches can be used to assist the assembly process. However, previous methods mostly focused on the assembly of other genotypes within the same species. We adapted and extended a reference-guided de novo assembly approach, which enables the usage of a related reference sequence to guide the genome assembly. In order to compare and evaluate de novo and our reference-guided de novo assembly approaches, we used a simulated data set of a repetitive and heterozygotic plant genome.The extended reference-guided de novo assembly approach almost always outperforms the corresponding de novo assembly program even when a reference of a different species is used. Similar improvements can be observed in high and low coverage situations. In addition, we show that a single evaluation metric, like the widely used N50 length, is not enough to properly rate assemblies as it not always points to the best assembly evaluated with other criteria. Therefore, we used the summed z-scores of 36 different statistics to evaluate the assemblies.The combination of reference mapping and de novo assembly provides a powerful tool to improve genome reconstruction by integrating information of a related genome. Our extension of the reference-guided de novo assembly approach enables the application of this strategy not only within but also between related species. Finally, the evaluation of genome assemblies is often not straight forward, as the truth is not known. Thus one should always use a combination of evaluation metrics, which not only try to assess the continuity but also the accuracy of an assembly.
| S-EPMC5681816 | biostudies-other
Project description:Chinese motherwort (Leonurus japonicus), a member of Lamiaceae family, is a commonly used medicinal herb for treating obstetrical and gynecological diseases, producing over 280 officinal natural products. Due to limited genomic resources, little progress has been made in deciphering the biosynthetic pathway of valuable natural products in L. japonicus. Here, we de novo assembled the L. japonicus genome using high-coverage ONT long reads and Hi-C reads. The chromosome-level genome assembly contained ten chromosomes representing 99.29% of 489.34 Mb genomic sequence with a contig and scaffold N50 of 7.27 Mb and 50.86 Mb, respectively. Genome validations revealed BUSCO and LAI score of 99.2% and 21.99, respectively, suggesting high quality of genome assembly. Using transcriptomic data from various tissues, 22,531 protein-coding genes were annotated. Phylogenomic analysis of 13 angiosperm plants suggested L. japonicus had 58 expanded gene families functionally enriched in specialized metabolism such as diterpenoid biosynthesis. The genome assembly, annotation, and sequencing data provide resources for the elucidation of biosynthetic pathways behind natural products of pharmaceutical applications in L. japonicus.
| S-EPMC10776605 | biostudies-literature
Project description:For over a thousand years, the common goldfish (Carassius auratus) was raised throughout Asia for food and as an ornamental pet. As a very close relative of the common carp (Cyprinus carpio), goldfish share the recent genome duplication that occurred approximately 14 million years ago in their common ancestor. The combination of centuries of breeding and a wide array of interesting body morphologies provides an exciting opportunity to link genotype to phenotype and to understand the dynamics of genome evolution and speciation. We generated a high-quality draft sequence and gene annotations of a "Wakin" goldfish using 71X PacBio long reads. The two subgenomes in goldfish retained extensive synteny and collinearity between goldfish and zebrafish. However, genes were lost quickly after the carp whole-genome duplication, and the expression of 30% of the retained duplicated gene diverged substantially across seven tissues sampled. Loss of sequence identity and/or exons determined the divergence of the expression levels across all tissues, while loss of conserved noncoding elements determined expression variance between different tissues. This assembly provides an important resource for comparative genomics and understanding the causes of goldfish variants.
| S-EPMC6594761 | biostudies-literature
Project description:Upriver orange mangrove (Bruguiera sexangula) is a member of the most mangrove-rich taxon (Rhizophoraceae family) and is commonly distributed in the intertidal zones in tropical and subtropical latitudes. In this study, we employed the 10× Genomics linked-read technology to obtain a preliminary de novo assembly of the B. sexangula genome, which was further scaffolded to a pseudomolecule level using the Bruguiera parviflora genome as a reference. The final assembly of the B. sexangula genome contained 260 Mb with an N50 scaffold length of 11,020,310 bases. The assembly comprised 18 pseudomolecules (corresponding to the haploid chromosome number in B. sexangula), covering 204,645,832 bases or 78.6% of the 260-Mb assembly. We predicted a total of 23,978 protein-coding sequences, 17,598 of which were associated with gene ontology terms. Our gene prediction recovered 96.6% of the highly conserved orthologs based on the Benchmarking Universal Single-Copy Orthologs (BUSCO) analysis. The chromosome-level assembly presented in this work provides a valuable genetic resource to help strengthen our understanding of mangroves' physiological and morphological adaptations to the intertidal zones.
| S-EPMC8872974 | biostudies-literature
Project description:Major advances in selection progress for cattle have been made following the introduction of genomic tools over the past 10-12 years. These tools depend upon the Bos taurus reference genome (UMD3.1.1), which was created using now-outdated technologies and is hindered by a variety of deficiencies and inaccuracies. We present the new reference genome for cattle, ARS-UCD1.2, based on the same animal as the original to facilitate transfer and interpretation of results obtained from the earlier version, but applying a combination of modern technologies in a de novo assembly to increase continuity, accuracy, and completeness. The assembly includes 2.7 Gb and is >250× more continuous than the original assembly, with contig N50 >25 Mb and L50 of 32. We also greatly expanded supporting RNA-based data for annotation that identifies 30,396 total genes (21,039 protein coding). The new reference assembly is accessible in annotated form for public use. We demonstrate that improved continuity of assembled sequence warrants the adoption of ARS-UCD1.2 as the new cattle reference genome and that increased assembly accuracy will benefit future research on this species.
| S-EPMC7081964 | biostudies-literature
Project description:Genomes assembled de novo from short reads are highly fragmented relative to the finished chromosomes of Homo sapiens and key model organisms generated by the Human Genome Project. To address this problem, we need scalable, cost-effective methods to obtain assemblies with chromosome-scale contiguity. Here we show that genome-wide chromatin interaction data sets, such as those generated by Hi-C, are a rich source of long-range information for assigning, ordering and orienting genomic sequences to chromosomes, including across centromeres. To exploit this finding, we developed an algorithm that uses Hi-C data for ultra-long-range scaffolding of de novo genome assemblies. We demonstrate the approach by combining shotgun fragment and short jump mate-pair sequences with Hi-C data to generate chromosome-scale de novo assemblies of the human, mouse and Drosophila genomes, achieving--for the human genome--98% accuracy in assigning scaffolds to chromosome groups and 99% accuracy in ordering and orienting scaffolds within chromosome groups. Hi-C data can also be used to validate chromosomal translocations in cancer genomes.
| S-EPMC4117202 | biostudies-literature