Bioinformatics at COMAV

Walktroughs for the final tasks

Clean adapters and contaminants


ngs_user@machine:~/clean$ calculate_stats -c to_clean_454.fastq.gz | less
ngs_user@machine:~/clean$ calculate_stats -c to_clean_illumina.fastq.gz | less

Remove the adaptor:

ngs_user@machine:~/clean$ trim_blast_short -z -l AAGCAGTGGTATCAACGCAGAGTACGCGGG -l AAGCAGTGGTATCAACGCAGAGTACATGGG -l AAGCAGTGGTATCAACGCAGAGTAC -o 454_no_adapt.fastq.gz to_clean_454.fastq.gz
ngs_user@machine:~/clean$ trim_blast_short -z -l AAGCAGTGGTATCAACGCAGAGTACGCGGG -l AAGCAGTGGTATCAACGCAGAGTACATGGG -l AAGCAGTGGTATCAACGCAGAGTAC -o illumina_no_adapt.fastq.gz to_clean_illumina.fastq.gz
ngs_user@machine:~/clean$ calculate_stats -c 454_no_adapt.fastq.gz | less
ngs_user@machine:~/clean$ calculate_stats -c illumina_no_adapt.fastq.gz | less

Remove bad quality regions and filter out the small reads:

ngs_user@machine:~/clean$ trim_quality -z -o 454_qual.fastq.gz 454_no_adapt.fastq.gz
ngs_user@machine:~/clean$ trim_quality -z -o illumina_qual.fastq.gz illumina_no_adapt.fastq.gz
ngs_user@machine:~/clean$ filter_by_length -z -n 30 -o 454_clean.fastq.gz 454_no_adapt.fastq.gz
ngs_user@machine:~/clean$ filter_by_length -z -n 30 -o illumina_clean.fastq.gz illumina_no_adapt.fastq.gz

Remove the ribosomic reads:

ngs_user@machine:~/clean$ filter_by_blast -z -o no_ribo_454.fastq.gz -b arabidpsis_rrna.fasta -g blastn -x 0.000001 -e 454_ribo.fastq 454_clean.fastq.gz

Split 454 matepairs

Split the mate pairs:

~/mates$ split_matepairs -l 454 -o 454_mates.split.fastq 454_mates.fastq

Trim by quality and filter by length:

~/mates$ trim_quality -o 454_mates.qual.fastq 454_mates.split.fastq
~/mates$ filter_by_length -n 40 -o 454_mates.len.fastq 454_mates.qual.fastq

Recover mates still standing in two files and the rest in another file (orphan.fastq):

~/mates$ pair_matcher -o pairs.fastq -p orphan.fastq 454_mates.len.fastq
~/mates$ deinterleave_pairs -o mate1.fastq mate2.fastq pairs.fastq

Mithocondrial assembly

The assembly phase could be:

ngs_user@machine:~/mito$ velveth  assem 31 -fastq.gz -shortPaired  mito_yoruba_reads_pe.20k.fastq.gz
ngs_user@machine:~/mito$ velvetg assem/ -ins_length 500 -exp_cov 30.0 -read_trkg yes -amos_file yes
ngs_user@machine:~/mito$ calculate_stats assem/contigs.fa

Map to the mithocondrial assembly

First we have to create an index with bwa:

ngs_user@machine:~/mito$ cd
ngs_user@machine:~$ cd mito/assem/
ngs_user@machine:~/mito/assem$ bwa index -p contigs contigs.fa
[bwa_index] Pack FASTA... 0.00 sec
[bwa_index] Construct BWT for the packed sequence...
[bwa_index] 0.00 seconds elapse.
[bwa_index] Update BWT... 0.00 sec
[bwa_index] Pack forward-only FASTA... 0.01 sec
[bwa_index] Construct SA from BWT and Occ... 0.00 sec
[main] Version: 0.6.1-r104
[main] CMD: bwa index -p contigs contigs.fa
[main] Real time: 0.020 sec; CPU: 0.020 sec

The mapping:

ngs_user@machine:~/mito/assem$ deinterleave_pairs -o reads_1.fastq reads_2.fastq ../mito_yoruba_reads_pe.20k.fastq.gz
ngs_user@machine:~/mito/assem$ bwa aln contigs reads_1.fastq > reads_1.sai
[bwa_aln] 17bp reads: max_diff = 2
[bwa_aln] 38bp reads: max_diff = 3
[bwa_aln] 64bp reads: max_diff = 4
[bwa_aln] 93bp reads: max_diff = 5
[bwa_aln] 124bp reads: max_diff = 6
[bwa_aln] 157bp reads: max_diff = 7
[bwa_aln] 190bp reads: max_diff = 8
[bwa_aln] 225bp reads: max_diff = 9
[bwa_aln_core] calculate SA coordinate... 0.30 sec
[bwa_aln_core] write to the disk... 0.00 sec
[bwa_aln_core] 10000 sequences have been processed.
[main] Version: 0.6.1-r104
[main] CMD: bwa aln contigs reads_1.fastq
[main] Real time: 0.388 sec; CPU: 0.352 sec
ngs_user@machine:~/mito/assem$ bwa aln contigs reads_2.fastq > reads_2.sai
[bwa_aln] 17bp reads: max_diff = 2
[bwa_aln] 38bp reads: max_diff = 3
[bwa_aln] 64bp reads: max_diff = 4
[bwa_aln] 93bp reads: max_diff = 5
[bwa_aln] 124bp reads: max_diff = 6
[bwa_aln] 157bp reads: max_diff = 7
[bwa_aln] 190bp reads: max_diff = 8
[bwa_aln] 225bp reads: max_diff = 9
[bwa_aln_core] calculate SA coordinate... 0.31 sec
[bwa_aln_core] write to the disk... 0.00 sec
[bwa_aln_core] 10000 sequences have been processed.
[main] Version: 0.6.1-r104
[main] CMD: bwa aln contigs reads_2.fastq
[main] Real time: 0.376 sec; CPU: 0.352 sec
ngs_user@machine:~/mito/assem$ bwa sampe contigs reads_1.sai reads_2.sai reads_1.fastq reads_2.fastq > mapping.sam
[bwa_sai2sam_pe_core] convert to sequence coordinate...
[infer_isize] (25, 50, 75) percentile: (467, 502, 535)
[infer_isize] low and high boundaries: 331 and 671 for estimating avg and std
[infer_isize] inferred external isize from 8691 pairs: 501.343 +/- 50.302
[infer_isize] skewness: -0.008; kurtosis: -0.096; ap_prior: 2.64e-05
[infer_isize] inferred maximum insert size: 751 (4.96 sigma)
[bwa_sai2sam_pe_core] time elapses: 0.11 sec
[bwa_sai2sam_pe_core] changing coordinates of 7 alignments.
[bwa_sai2sam_pe_core] align unmapped mate...
[bwa_paired_sw] 1030 out of 1245 Q17 singletons are mated.
[bwa_paired_sw] 5 out of 18 Q17 discordant pairs are fixed.
[bwa_sai2sam_pe_core] time elapses: 0.32 sec
[bwa_sai2sam_pe_core] refine gapped alignments... 0.01 sec
[bwa_sai2sam_pe_core] print alignments... 0.09 sec
[bwa_sai2sam_pe_core] 10000 sequences have been processed.
[main] Version: 0.6.1-r104
[main] CMD: bwa sampe contigs reads_1.sai reads_2.sai reads_1.fastq reads_2.fastq
[main] Real time: 0.712 sec; CPU: 0.604 sec

SAM manipulation:

ngs_user@machine:~/mito/assem$ samtools view -hS -b -o mapping.bam mapping.sam
[samopen] SAM header is present: 57 sequences.
ngs_user@machine:~/mito/assem$ samtools sort mapping.bam mapping.sorted
ngs_user@machine:~/mito/assem$ samtools index mapping.sorted.bam
ngs_user@machine:~/mito/assem$ ls *bam*
mapping.bam  mapping.sorted.bam  mapping.sorted.bam.bai

Now we can open it with IGV.

Human Mithocondrial SNP calling

With bowtie2 and samtools:

ngs_user@machine:~/yoruba$ bowtie2-build human_cambridge_reference_mito.fasta mito_index
Reading reference sizes
  Time reading reference sizes: 00:00:00
  Calculating joined length
  Writing header
  Reserving space for joined string
ngs_user@machine:~/yoruba$ bowtie2 --sensitive -x mito_index -U mito_yoruba_reads_40k.fastq.gz -S yoru_cam.sam
40000 reads; of these:
  40000 (100.00%) were unpaired; of these:
    2030 (5.08%) aligned 0 times
    37970 (94.92%) aligned exactly 1 time
    0 (0.00%) aligned >1 times
94.92% overall alignment rate
ngs_user@machine:~/yoruba$ samtools view -hS -b -o yoru_cam.bam yoru_cam.sam
[samopen] SAM header is present: 1 sequences.
ngs_user@machine:~/yoruba$ samtools sort yoru_cam.bam yoru_cam.sorted
ngs_user@machine:~/yoruba$ samtools mpileup -ugf human_cambridge_reference_mito.fasta yoru_cam.sorted.bam | bcftools view -bvcg - > var.raw.bcf
[mpileup] 1 samples in 1 input files
<mpileup> Set max per-file depth to 8000
[afs] 0:15458.987 1:10.826 2:54.187
ngs_user@machine:~/yoruba$ bcftools view var.raw.bcf | varFilter -D100 > var.flt.vcf
ngs_user@machine:~/yoruba$ less var.flt.vcf

To open the vcf with IGV we have to compress it and index it:

ngs_user@machine:~/yoruba$ bgzip var.flt.vcf
ngs_user@machine:~/yoruba$ tabix -p vcf var.flt.vcf.gz

With ngs_backbone:

ngs_user@machine:~$ -p yoruba
ngs_user@machine:~$ cd yoruba/
ngs_user@machine:~/yoruba$ mkdir reads
ngs_user@machine:~/yoruba$ mkdir reads/cleaned
ngs_user@machine:~/yoruba$ ls reads/cleaned/
ngs_user@machine:~/yoruba$ cd reads/cleaned/
ngs_user@machine:~/yoruba/reads/cleaned$ gunzip mito_yoruba_reads_40k.fastq.gz
ngs_user@machine:~/yoruba/reads/cleaned$ mv mito_yoruba_reads_40k.fastq sm_yoruba.pl_illumina.lb_yoruba.sfastq
ngs_user@machine:~/yoruba/reads/cleaned$ ls
ngs_user@machine:~/yoruba/reads/cleaned$ cd ..
ngs_user@machine:~/yoruba/reads$ cd ..
ngs_user@machine:~/yoruba$ mkdir mapping
ngs_user@machine:~/yoruba$ mkdir mapping/reference
ngs_user@machine:~/yoruba$ ls mapping/reference/
ngs_user@machine:~/yoruba$ -a mapping,merge_bams,calmd_bam
2012-12-10 16:38:51,494 INFO MappingAnalyzer
2012-12-10 16:38:51,494 INFO backbone version: 1.4.0
2012-12-10 16:38:51,495 INFO Analysis started
2012-12-10 16:38:55,762 INFO Analysis finished
2012-12-10 16:38:55,764 INFO Time elapsed 0:00:04.400516
2012-12-10 16:38:55,843 INFO MergeBamAnalyzer
2012-12-10 16:38:55,846 INFO Analysis started
2012-12-10 16:38:59,202 INFO Analysis finished
2012-12-10 16:38:59,227 INFO Time elapsed 0:00:03.462259
2012-12-10 16:38:59,276 INFO CalmdBamAnalyzer
2012-12-10 16:38:59,280 INFO Analysis started
2012-12-10 16:39:01,598 INFO Analysis finished
2012-12-10 16:39:01,602 INFO Time elapsed 0:00:02.374086
ngs_user@machine:~/yoruba$ -a mapping_stats
2012-12-10 16:44:10,667 INFO BamStatsAnalyzer
2012-12-10 16:44:10,669 INFO backbone version: 1.4.0
2012-12-10 16:44:10,670 INFO Analysis started
2012-12-10 16:44:15,980 INFO Time elapsed 0:00:05.341456
ngs_user@machine:~/yoruba$ less mapping/bams/stats/statistics.txt
Statistics for merged.1.bam
General mapping statistics
Read group    Sample  Library Platform        Num mapped reads        % mapped
yoruba_illumina_yoruba        yoruba  yoruba  illumina        40000   95.025

Total number of reads: 40000
Reads aligned: 38010 (95.0%)
Reads not aligned: 1990 (5.0%)
ngs_user@machine:~/yoruba$ mkdir annotations
ngs_user@machine:~/yoruba$ mkdir annotations/input
ngs_user@machine:~/yoruba$ cp mapping/reference/reference.fasta annotations/input/yoruba.fasta
ngs_user@machine:~/yoruba$ -a annotate_snvs,write_annotations,annotation_stats
2012-12-10 16:42:55,010 INFO SnvCallerAnalyzer
2012-12-10 16:42:55,012 INFO backbone version: 1.4.0
2012-12-10 16:42:55,013 INFO Analysis started
2012-12-10 16:42:55,015 INFO Analysis finished
2012-12-10 16:42:55,016 INFO Time elapsed 0:00:00.043499

Obtain the SNP flanking sequence

Which SNPs are shared by the samtools and ngs_backbone SNP callings?

ngs_user@machine:~/mito$ cp var.flt.vcf.gz sam.vcf.gz
ngs_user@machine:~/mito$ gunzip sam.vcf.gz
ngs_user@machine:~/mito$ cp yoruba/annotations/features/yoruba.vcf.gz back.vcf.gz
ngs_user@machine:~/mito$ gunzip back.vcf.gz
ngs_user@machine:~/mito$ ls *vcf
back.vcf  sam.vcf
ngs_user@machine:~/mito$ intersectBed -a back.vcf -b sam.vcf  > common_snps.vcf

Which is the sequence around these SNPs?

ngs_user@machine:~/mito$ calculate_stats human_cambridge_reference_mito.fasta
Length stats and distribution.
N50: 16569
N95: 16569
minimum: 16,569
maximum: 16,569
average: 16569.00
variance: 0.00
tot. residues: 16,569
ngs_user@machine:~/mito$ gedit mito.genome
ngs_user@machine:~/mito$ cat mito.genome
gi|251831106|ref|NC_012920.1|  16569
ngs_user@machine:~/mito$ cut -f 1,2 common_snps.vcf > common_snps_col_1_2.bed
ngs_user@machine:~/mito$ cut -f 2 common_snps.vcf > common_snps_col_3.bed
ngs_user@machine:~/mito$ paste common_snps_col_1_2.bed common_snps_col_3.bed > common_snps.bed
ngs_user@machine:~/mito$ flankBed -i common_snps.bed -g mito.genome -b 100 > flanking.bed
ngs_user@machine:~/mito$ fastaFromBed -fi human_cambridge_reference_mito.fasta -bed flanking.bed -fo flanking.fasta