Questions tagged [long-reads]

Questions relating to long reads, such as pacbio or nanopore reads.

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rMATS and SUPPA on long read sequences?

Has anyone in the community used rMATs or SUPPA for differential splicing analysis in long read data? I have tried using SUPPA2 in PacBio Isoseq + MinION RNA-seq data and can identify the differential ...
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1answer
24 views

Chromosomal order of supplementary alignment in BAM file “SA” tag

I have several long-read sequences, which when aligned to a human reference genome, aligns to multiple chromosomal fragment as a result of chromothripsis shattering the linear DNA and randomly piecing ...
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53 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 got contigs.fa from short reads but phasing step with PacBio ...
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1answer
54 views

Why does samtools mpileup sometimes include ref bases (other than ',' or '.')?

This is my first post here. I can think of no way of giving an easily reproducible example, as per the stack ethos. SO apologies in advance and any feedback on question format appreciated. I have ...
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2answers
103 views

What assembler is appropriate for High-Fidelity PacBio reads

What assembler is appropriate for High-Fidelity PacBio reads? For example, canu is good for high-error PacBio reads. But what algorithm to use for HiFi reads? Would it be OK to use canu without the ...
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74 views

nanopore - where to retrieve information from the basecaller used

Where can I find information about the basecaller used in a specific nanopore run (we have a Gridion machine)? I know already that we have Guppy v. 3.0.3, which I ...
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1answer
72 views

BED file from .bam alignment structure

I am using a pipeline from nanopore to detect structural variants (SVs) in a human sample with long-reads sequencing. The first steps of the pipeline are: index the reference genome with ...
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1answer
316 views

Is nanopolish worth it since faster polishing software is available?

For Oxford Nanopore contigs produced by any long-read assembler has anyone performed any benchmarks to compare the polishing tools racon, ...
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1answer
176 views

Questions regarding Nanopore sequencing analysis

I am new to Nanopore sequencing analysis. I have a couple of questions regarding it which are as follows: How do I know if my fast5 file is multiread or single read file? Is there a way to combine ...
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252 views

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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3answers
2k views

Why Illumina if PacBio provides longer and better reads?

PacBio provides longer read length than Illumina's short-length reads. Longer reads offer better opportunity for genome assembly, structural variant calling. It is not worse than short reads for ...
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233 views

Mapping Reads to Known Gene Paralogs with Long Read Technology

I have some sequencing data from a captured region that is a known paralog edited. For now, I have been mapping the data using standard minimap2 flags for PacBio DNA sequencing: ...
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210 views

calling diploid SNVs from long reads

I'd like to call diploid SNV variants from long-reads data (~80SMRTcells PacBio). I have generated a draft reference genome for an indivudual from a heterozygous (~4%) species (Canu+Haplomerger2). ...
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1answer
219 views

Error correction within the long read

I am going to get some data from plasmid sequencing to identify SNPs on the plasmids. What is done in the lab is the following: The plasmids are purified by size. We amplify the plasmids using the ...
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1answer
67 views

Using ONT MinION, why is that we cannot get a full length DNA read?

Here, https://www.youtube.com/watch?v=E9-Rm5AoZGw, ONT claims they can read non-fragmented DNA and that with the hairpin like structure the double strands can be read at once. Then why is that MinION ...
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513 views

How to simulate nanopore reads?

I have looked already here: Tools for simulating Oxford Nanopore reads . This doesn't answer my question, because it lists a few Nanopore read simulators, but I have specific problems with each of ...
4
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1answer
298 views

How to map short sequences to long reads, recovering all multiply-mapped high-quality matches

The dilemma: I have a problem where I have around one million short sequences (21 bp to several 100s of basepairs) for which I need to identify all occurrences of in 20-30x coverage noisy long reads (...
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1answer
549 views

Can I pilon-polish long reads with Illumina short reads to improve structural variant detection?

I have pacbio Sequel data at 50 x coverage for a strain of animal. I would like to find structural variants compared to the reference genome sequence. At the moment, I align my reads to the reference ...
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54 views

Canu failed with 'didn't find any mers?'

I have installed canu using conda in an environment containing Python 3 on a Mac OS X. I checked that canu is properly installed by pulling out the help and it works. I launched a canu assembly job by ...
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2answers
1k views

Can I stop my nanopore sequencing run if there are no more reads being produced?

I am sequencing a whole genome on MinION. I have used this flow cell for 6 hours for the phage lambda control. That gave me around 300,000 reads. I started a 48h sequencing run on the same flow cell ...
2
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1answer
152 views

How to interpret the SMRT Link base modification algorithm output?

I have got PacBio data from a Sequel machine at a coverage > 50X. I have run it in SMRT Link with their Base Modification Detection algorithm. I am now trying to figure out how to interpret the output ...
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1answer
807 views

How many reads has my sequencing run produced on minion?

I am running a 48 h sequencing protocol on a FLO-MIN107, on MinION, with DNA library-prepped with SQK-RAD004. MinKNOW is installed on my Mac and controlling the MinION. I have found the following ...
2
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1answer
320 views

What to do with the configuration test cell after configuring the MinION with it?

What to do with the configuration test cell after configuring the MinION with it? I received a MinION with a configuration test cell in it. After running a configuration in the MinKNOW software while ...
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1answer
542 views

Does MinKNOW work with Mac OSX high sierra 10.13.1?

I have done a compatibility check as described here on my computer to know if I can use MinKNOW on my mac laptop. It says that my OS is incompatible and that the OSX must be Yosemite or El Capitan. ...
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1answer
111 views

Scaffolding a genome with hybrid data

I am assembling a ~500MB genome, and have ~150x long reads and ~200x 150bp PE short reads, with a ~400bp insert size. I've done a lot of work with minimap+miniasm, and have what I think is a good set ...
7
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1answer
681 views

Coverage calculation: long reads (RNA-seq)

Say your aim is to calculate the coverage of an RNA-seq experiment generated with long-read sequencing (so, uneven read length). Up to now, I relied on the Lander/Waterman equation: $$C = L*N / G$$...
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1answer
316 views

Mark BWA-SW split alignments in output for long reads

Is there a way to remove split alignments of single-end long reads from BWA-SW output? BWA-MEM has an option to include or flag split alignments in the result, but it seems BWA-SW method include them ...
7
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1answer
820 views

How can I use Nanopore reads to close gaps or resolve repeats in a short-read assembly?

Low coverage MinION reads should be useful to close gaps and resolve repeats left by short-read assemblers. However, I haven't had any success with the software I know about. I'm aware of the ...
5
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1answer
182 views

Detecting structural variants with MinION data

Working on various cancers I have an interest in detecting structural variation (SV) in human, we've successfully used various tools like Pindel, SVDetect, Manta, and LUMPY, to name a few for ...
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2answers
227 views

Finding the location and unit length of repetitive sequences within a long read

After discovering a few difficulties with genome assembly, I've taken an interest in finding and categorising repetitive DNA sequences, such as this one from Nippostrongylus brasiliensis [each base is ...
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2answers
141 views

Structural variant calling for low-coverage PacBio data

PacBio is selling ~10x PacBio SEQUEL long reads as an upgrade to Illumina data for SV discovery. In a clinical setting, the main requirements are proper sensitivity and specificity but also the ...
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1answer
200 views

Rapid metagenomics classifiers on long read data [closed]

I recently used the minION (Nanopore, 9.4 flow cell, RAD001 kit) to generate a metagenome out of environmental samples. Passed reads weren't brilliant (196, average 1,594bp lenght), but working with ...
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1answer
477 views

How can I improve a long-read assembly with a repetitive genome?

I'm currently trying to assembly a genome from a rodent parasite, Nippostrongylus brasiliensis. This genome does have an existing reference genome, but it is highly fragmented. Here are some ...
16
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573 views

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 - ...