Questions tagged [assembly]

Process of creating the original sequence from the read sequences that it generated during a sequencing experiment. Can refer to genome assembly, in which case the original sequence is a genome, or transcripts assembly, in which case the original sequences are RNA transcripts.

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Merge / Reconciliate several de novo transcriptome assemblies with different kmers

I am building a De Novo transcriptome reference assembly for an eukaryotic organism for which I have a genome. I've created several assemblies with rnaSpades using different kmer sizes (19 to 69 with ...
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Will using smaller kmers help get larger contigs? If not, then what?

I've been using MEGAHIT to assemble metagenomes, with particular focus on specific genomic areas. Sometimes all I get is gene fragments or pathway fragments (eg. if I know that genes A, B, C, D and E ...
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polishing assembled genome to QV50 value

I am trying to assemble some genomes from pacbio reads using HGAP3 followed by quiver polishing. However, even after multiple rounds of quiver polishing, I cannot attain quality value 50 (QV50) for a ...
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49 views

Interpreting contig alignments to a reference genome

I have applied two de novo genome assembly tools to data from the run SRR12707453, corresponding to a phage (I downloaded the data and have no relation with the authors of the study). Using rnaSPAdes ...
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1answer
178 views

Coverage required

I was came across a problem during an exercise in a book and I don't really know how to solve it. I feel like something's missing. "coverage, c = $NL/G$ (N=number of reads, L=read length, G=genome ...
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Genome QC + Assembly Pipeline semantics

I’m trying to create a pipeline for genome assembly. How best can I “redirect/pipe” from existing fasta files (or files in general) to other steps of the pipeline? I was thinking of going from the SRA ...
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1answer
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Can SBOL encode DNA Assembly linkers?

Where in an SBOL file could you specify the linkers that would be placed as prefixes / suffixes between parts for assembly? Lets say you have a final construct of your design and want to assemble the ...
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56 views

creating a tab delimited file

I am working on a project using a fasta file. I am writing my command in nano within command-line and executing using python, also within my command-line. I would like my command to provide me with a ...
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2answers
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Is it possible to filter contaminated reads for raw PacBio sequences (not HiFi reads) before assembly?

De novo genome assembly for non-model organisms face the issue of bacterial contamination. For assembled contigs with mostly bacterial-like sequences (based on BLAST search), the entire contig can be ...
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wtdbg2: practical implications of k-mer fsize and psize choice

I am using wtdbg2 2.3 to assemble a human genome (sequenced on PromethION from a cell line). I filtered out reads with low average quality, and now I am trying to determine the parameters that will ...
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Is there any value in scaffolding the output contigs of MEGAHIT assembler given a metagenomic dataset?

As far as I understood, for most assembly programs, the scaffolding step takes into consideration paired-end information in order to get from contigs (contiguous sequences) to scaffolds (longer ...
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Quast duplication ratio and mismatches percent

When analyzing Quast results it seems that it doesn't calculate mismatches and indels in a useful way if the "Duplication ratio" is over 1. For example, that's what I get for an assembly ...
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1answer
38 views

Gold standard benchmark

This page is claimed to contain a gold standard benchmark for viral genome assembly. https://github.com/cbg-ethz/5-virus-mix The claim is here: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5411778/ &...
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How to deal with heterozygosity during polishing of genome assembly based on long reads?

All the long-read sequencing platforms are based on single-molecule sequencing which causes higher per-base error rates. For this reason a polishing step was added to genome assembly pipelines - ...
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4answers
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Tools for comparing/visualizing FASTAs?

I have two FASTAs/assemblies of the same species, but the bases are somewhat different. I would like to explore this. What tools/methods exist to compare two FASTAs and see the difference in ...
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How can I get or create a reference genome for Bacteria?

I am a computer engineer and nowadays trying to grasp some concepts of Bioinformatics particularly, reference genomes and genomic variants. My aim is to find the effect of sequence features on variant ...
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1answer
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Which one is a more convenient assembly?

I have developed a software for de novo genome assembly. Its performance varies gradually according to how much data you employ. At initial stages it often produces contigs that look like that when ...
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0answers
39 views

How to filter a genome assembly consistsing of a large number of contigs?

I did some de novo genome assemblies with Illumina PE data using SPAdes, whereas most of them consisting of a large number of contigs(>1000). I have several questions below. Do we need to filter ...
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Repeat analysis on eukaryotic assemblies

I have a hundred insect genomes and I'm looking for repeated regions along these assemblies. First of all, I thought of using <...
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1answer
75 views

Viral genome assembly using broad viral ngs pipeline?

I am trying to assemble RNA virus genome using Broad Viral NGS pipeline BROAD VIRAL NGS PIPELINE. I am two questions : 1) As this pipeline requires unaligned bam format as input, how do I convert ...
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1answer
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What is the meaning of these misaligned reads in a sequencing run?

I am analyzing some SARS-CoV-2 sequencing runs abd often find read alignments like the one in the image. ...
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2answers
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Bacterial DNA at the tail of transcriptome reads. What does that mean?

I am assembling a transcriptome obtained from the Internet. The transcriptome was extracted from a human cancer tissue that had been previously grafted into a mouse. I have detected that many ...
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1answer
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Viral genome finishing

I have assembled poxvirus genome using Ray. The assembly is good. Out of several thousand contigs I got, I was able to get one scaffold using Contiguator tool, which is about 90% of my genome. I have ...
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1answer
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Is there a simple command for outputting a tab delimited columns?

I am working on a fasta file and am writing my command in nano within command-line and executing using python, also within a command line. My objective is to get my command to provide me with a tab ...
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2answers
107 views

Contamination on genome assembly

I had a question for the community. I have a genome of a new species that has been sequenced via 150pb Illumina paired-end. To verify the quality of the assembly I used the ...
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1answer
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Is it possible to convert BAM file from one genome assembly to the other?

I Have multiple BAM files that are referenced to UCSC genome assembly GRCh37/hg19 that are read in different time frames. Now, I am planning a different studies that require assembling all the data ...
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1answer
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How to find all WGS assemblies accessions of a species

Some background Similar to the OP of https://www.biostars.org/p/377840/, I would like to programmatically BLAST a sequence to a local database of all WGS assemblies. Since this isn't feasible for the ...
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Genome assembly of SRR12196449 with SPAdes

I am trying to assemble the run SRR12196449 with SPAdes. The description of their project is: This project expected to standardize a method for amplification and ...
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1answer
33 views

Finding simple sequence from reads with significant overlap

I wrote a "script" to pull out reads from a huge fastq file in an iterative manner, by finding homology to the previous sequence. It should be relatively easy to overlap them and assemble ...
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1answer
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PacBio long-reads impact in transcriptome de novo assembly?

We are strongly interested in assembly a good transcriptome of reference for a non-model organism and build a local database. We have sequenced the same individual with Illumina (150 millions of pair-...
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1answer
120 views

Difference between paired-end, mate-pair and long read

I writing here because I have some questions for you. I wondered what the essential differences were between paired-end, ...
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After KEGG and GO analysis, how to make tables+phylogenetic trees

hope everyone is ok. I used Trinity to do a de novo transcriptome assembly, then blastp/blastx and then used Blast2GO software to do KEGG and GO analysis. So i got some txt files with header : for GO ...
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1answer
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RCSB API: limited returned result

Is there a limit of query results on RCSB API? Interestingly, no matter how to adjust my query criteria, only 10 assemblies are returned. Here is an example query json: (truncated from a longer query ...
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Which of the Transcriptome assembly method is best for identifying novel lncRNAs?

I'm working with human samples and I'm trying to identify novel lncRNAs from tumor samples of Prostate cancer. I'm using reference based transcriptome assembly with ...
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Filtering out nonarthropod sequences using Blobtools2

I am using Blobtools2 and am working my way through the sample dataset that they provide before using my own. The filtering tutorial I am following is --> https://blobtoolkit.genomehubs.org/...
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1answer
47 views

Gap-fill assembly with PacBio reads

I would like to gap-fill (or correct) a mammalian-sized assembly for which we have BACs that have been sequenced with PacBio CLR data. I have seen there are pbm22/gcpp tools available for correcting ...
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Resources to learn genome assembly workflow for small genomes (like viruses)

I have sequencing data of a few samples of a DNA genome virus. I'd like to learn de novo assembly of the ...
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1answer
182 views

Difference between genome assembly and genome sequence alignment to a reference to find structural variants

I'm trying to determine what the difference and benefits of genome assembly and genome sequence alignments are when trying to identify structural variants or transposons in populations. I've been ...
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1answer
131 views

Viral Metagenomics

I am analyzing viral metagenomics data (Illumina Miseq) for the first time. I have used Ray for de novo viral genome assembly before but I haven't done metagenomics analysis before. I know that there ...
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0answers
146 views

Platanus-allee phasing fail: Error(13): Error, SolveDBG exception!

I am using Platanus-allee 2.2.2 for heterozygous genome (~500mb) assembly with Illumina short reads and PacBio reads input data. I have the file contigs.fa from short reads but phasing step with ...
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2answers
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How to fragment genomes into non-overlapping sequences of differing sizes?

I have bacterial chromosomes/plasmids that I have downloaded off refseq in a multi-fasta that I would like to fragment into non-overlapping fragments of between 1 kb and 15 kb. I have tried googling ...
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1answer
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Comparing gene abundances between metagenomes

My workflow until now: Find fragments of a marker gene in unassembled metagenomes > download and assemble metagenomes > recover the gene neighborhood / gene set of interest Right now I have a ...
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1answer
48 views

Methods to predict one connected structure from two known separate structures

Currently, I am facing such a question: how to predict one connected protein structures from two separate known structures? It should be different from the protein-protein docking method, which is ...
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1answer
106 views

Decontaminating RNA seqs for de novo transcriptome assembly and annotation of novel eukaryotes

I have raw paired-end RNA-seq reads for two novel eukaryotic species. Some background: the reads represent a copepod (arthropod) species each. The mRNA for each read set was obtained by extracting ...
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Gffcompare issue: 0 reference transcripts loaded

I am trying to use gffcompare to compare my assembled transcriptome to a reference gtf that contains information about small open reading frames (sORFs). The reference gtf was obtained by processing ...
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1answer
108 views

“megahit: command not found” after correct installation with miniconda

I want to use MEGAHIT (git: https://github.com/voutcn/megahit) to assemble metagenome shotgun sequencing reads (illumina). I install the package with the command <...
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1answer
33 views

Assemble reads for a specific gene

I have a lot of unassembled sequencing data and I want to build phylogeny for some genes from these data. I can retrieved the sequene by mapping reads to a reference sequence but if the two species ...
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2answers
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Why do some assemblers require an odd-length kmer for the construction of de Bruijn graphs?

Why do some assemblers like SOAPdenovo2 or Velvet require an odd-length k-mer size for the construction of de Bruijn graph, while some other assemblers like ABySS are fine with even-length k-mers?
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estimate genome size: kmer-based approach from PacBio reads

Can anyone suggest a software/method for kmer analysis using PacBio reads (RSII)? Something similar to Jellyfish, that I saw in a nice tutorial - but must be suitable for long, noisy reads. ...