Hi Colin,

you solved it! That is exactly what is needed. Thank you. Now I can go to sleep and have sweet dreams.

What is this overlap detection supposed to achieve? It seems to sets reverse bases to 0 and perhaps takes their quality values and sums them together with quality of forward bases. That would explain why G values (38) most common in fastq/bam qualities are turn to m (76=38+38) in mpileup. But what is purpose of that?

Thank you, Colin.

Jiri

On 2/20/2017 11:18 PM, Colin Hercus wrote:
Hi Jiri,

That looks okay to me.

Samtools does have an option

  -x, --ignore-overlaps   disable read-pair overlap detection

perhaps you need to set that.


Colin

On 21 February 2017 at 12:32, Jiri Nehyba <ji...@utexas.edu <mailto:ji...@utexas.edu>> wrote:

    Hi Colin,

    here are couple of alignments from sam file. I used name sorting
    for this demonstration to show reads of both orientations
    together. Otherwise for mpile I am using the same bam file sorted
    by plain sort command.

    Jiri

M03964:25:000000000-AKT18:1:1101:1792:12037 83 chr16 3249344 42 173M = 3249342 -175 ACAACCCAGAGTTGTTGGGAAAATGAAGTAAGGCCCAGTGTGTCCAAGTGCCTGGCAGAGAAGAGCCCACAGGCAGGGAGTGCCTACCTTGTGTTCCAGGGCGACCTCCTCAATGGGGCGCACCCGGTGGCCTTGGTGCTCCTGACTCAGACTGCAGATGAGGCAGATGGGCT
    
GGGFGGGGFGGGGGGGGGFGGGGGGGFGFFGGFGGFCDGGFGGGGGGGGGGGGGGGFGGGGGGGGGGFFGGGFFGGCGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGEGFGGGGGGGGGGGGGGGGEGGGGGFGGG
AS:i:0 XN:i:0 XM:i:0 XO:i:0 XG:i:0 NM:i:0 MD:Z:173 YS:i:0 YT:Z:CP M03964:25:000000000-AKT18:1:1101:1792:12037 163 chr16 3249342 42 173M = 3249344 175 CAACAACCCAGAGTTGTTGGGAAAATGAAGTAAGGCCCAGTGTGTCCAAGTGCCTGGCAGAGAAGAGCCCACAGGCAGGGAGTGCCTACCTTGTGTTCCAGGGCGACCTCCTCAATGGGGCGCACCCGGTGGCCTTGGTGCTCCTGACTCAGACTGCAGATGAGGCAGATGGG
    
GGGGGGGGGDGGGGGGGGGCDGGF?FFFGAFGGGGGGGGFGGGGGGGGGGGGGGGGGGGEGGGGGGGGGFFECFF@EG7FCGGGGFGGGDFFGFFGGGGGG?CCCEFE>FGGGFFFCD8CEECGGGGGGGGGGGGGGGFCFCCGGFGF>F6F>FGGFGFDFFFAD>CAFFDAF
AS:i:0 XN:i:0 XM:i:0 XO:i:0 XG:i:0 NM:i:0 MD:Z:173 YS:i:0 YT:Z:CP M03964:25:000000000-AKT18:1:1101:1856:12139 83 chr16 3248843 42 198M = 3248841 -200 ACCCCTGCTCACTCTTCCCACCTTCCTCCCAGGGACGGATGGGCCATCAGCCACCTCTGACCTTACCAGAAAGCTCACTGCCTTCTCCTCCCCATAGGATCGCTGCTCCTCCCCTGATTTTCTCAGCTTCTTCAGATGCTCCAGCTGCTTCTGAATTTTCTTCTGGAAAAACAGCACTTGTTGAAAAGCTTGAATTTG
    
FDAFFFFGGGFGGDF@5C77GGC>GEGEGGFEEGGGGGGGGFGGGGFDEF6E8FGGGGFGGGGGFFGGGEA9GGGGFGGGGGGGGGGGGGGDGGFGGGFGGGGGGGEGGGGGFGGGFGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGFGGGGG
AS:i:0 XN:i:0 XM:i:0 XO:i:0 XG:i:0 NM:i:0 MD:Z:198 YS:i:-3 YT:Z:CP M03964:25:000000000-AKT18:1:1101:1856:12139 163 chr16 3248841 42 198M = 3248843 200 GGACCCCTGCTCACTCTTCCCACCTTCCTCCCAGGGACGGATGGGCCATCAGCCACCTCTGACCTTACCAGAAAGCTCACTGCCTTCTCCTCCCCATAGGATCGCTGCTCCTCCCCTGATTTTCTCAGCTTCTTCAGATGCTCCAGCTGCTTCTGACTTTTCTTCTGGAAAAACAGCACTTGTTGAAAAGCTTGAATT
    
GGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGFGGGGGGGGGGGGGGGGGGDEGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGFGGGGGGGGGFGGGGGGFGGGGEGGGCFGGGGGGGGGGGGFGGGGDGG+<D7FFGGFGFFFGFGFGF?5?FFFCFFF<@C5==@5@=CFF
AS:i:-3 XN:i:0 XM:i:1 XO:i:0 XG:i:0 NM:i:1 MD:Z:156A41 YS:i:0 YT:Z:CP M03964:25:000000000-AKT18:1:1101:1936:12864 83 chr16 3254291 42 159M = 3254289 -161 AATTTCTGGATTTGCGGGCGCCTTCTCCCCTGTAGAAATGGTGACCTCAAGGCTTCTAGGTCGCATCTTTCCCGAGGGCAGGTACACTTCGAAGGGCCTGCACTCCTTCTGCCCCGGGGCGCCCCCCGCCAGCCCCTGCAGCCTCCCCGCGGAGCTGGC
    
?CGC:<FF<7:E>GGC>>DF88ECEGGEC<<+7@F<CC?CFGGGDFGGGGGGGF9DGEE>E:C7FGGFEGGDEE<EGFGGFGGGGGEFFGE6G?;5@CGGGGGGGGGGCEEE:GGGGGCCGGGGGCGGEDGF@7FGGGEGDGGGGGEEGCEE<GGGGDF
AS:i:0 XN:i:0 XM:i:0 XO:i:0 XG:i:0 NM:i:0 MD:Z:159 YS:i:0 YT:Z:CP M03964:25:000000000-AKT18:1:1101:1936:12864 163 chr16 3254289 42 159M = 3254291 161 AGAATTTCTGGATTTGCGGGCGCCTTCTCCCCTGTAGAAATGGTGACCTCAAGGCTTCTAGGTCGCATCTTTCCCGAGGGCAGGTACACTTCGAAGGGCCTGCACTCCTTCTGCCCCGGGGCGCCCCCCGCCAGCCCCTGCAGCCTCCCCGCGGAGCTG
    
FCFGAEFCF9CEGGFFFGGGGEEGG:<@<:@B<FGGGGGGAF,C<EGFGD@FCA@FFFFGC,9C:@C@:FFG,EFGGGCB@F?@EFGFGCFDEG,BCGGGCEDCF>DFG9E9@DDFGC=6+@EEGG:@:EGGG*=:8**?F4D=<49EE7DDG557C46
AS:i:0 XN:i:0 XM:i:0 XO:i:0 XG:i:0 NM:i:0 MD:Z:159 YS:i:0 YT:Z:CP M03964:25:000000000-AKT18:1:1101:1992:12226 83 chr16 3243623 42 218M = 3243621 -220 GTCTAACACTCTTCAGATCATCAGAGAAGATGAGGTTGGGGTAAGCGGTTTCTGCATCCAGAATCACATTAACTGCAAAGAAAATTTGAATACCTAGGTAGGGGTCCATGGGCAACATCCCTACAGGGTTCTCCCCACCTGCAGGAAACAGGGACAGGGTAGTTCTTCTGGAACGTGGTAGGGGAGAGCACAGGGATCCAGCAGGCCAGGGCCACTTG
    
AFFFAFB:;+AFFA6FFFGFFGFGFFFGGGFFC>GGD?C6FEGGGED@CFGGGFDCFDECE,38FFEAGGGFGGGGGGGGGGECGGGGGCEFF@F9A=GGECFGGGGGDGEFGGGGGGGGGGGGE@CGGGGGGGGGGGGGGGGGGFGGGGFFGGGFGGFGGFGGGGGFGGFCGGGGGGGGDGGFCGFGGGFCFE@EFFDGFGFDCGGFF?GFFFFGFF
AS:i:0 XN:i:0 XM:i:0 XO:i:0 XG:i:0 NM:i:0 MD:Z:218 YS:i:-8 YT:Z:CP M03964:25:000000000-AKT18:1:1101:1992:12226 163 chr16 3243621 42 218M = 3243623 220 AAGTCTAACACTCTTCAGATCATCAGAGAAGATGAGGTTGGGGTAAGCGGTTTCTGCATCCAGAATCACATTAACTGCAAAGAAAATTTGAATACCGAGGTAGGGGTCCATGGGCAACATCCCTACAGGGTTATCCCCACCTGCAGGAAACAGGGACAGGGTAGTTCTTCTGGAACGTGGTAGGGGAGAGGACAGGGATCCAGCAGGCCAGGGCCACT
    
EEGCFDGFFEFFFD9CDEEFGGGFGGFGE,@@<AEF?C@E@FCFDGFFFE,@:EEFGFAE,B@FF,?AAFA9FFEFG,EFEFFF,,AFC,A<EFG,,@>CC4C@BC=?F?9EDCGGGF=,@DFGGGEC88D,+6@=2@D>E6=EFGGCG61=DDD?=*=?8*8=?F7CA+3<8@?5<F?>5@A5?)*:8))0::@BAD94>0*7((/58(/885>?04
    AS:i:-8 XN:i:0  XM:i:3  XO:i:0  XG:i:0  NM:i:3
    MD:Z:96T35C57C27        YS:i:0  YT:Z:CP
M03964:25:000000000-AKT18:1:1101:2092:11235 99 chr16 3254128 42 189M = 3254130 191 CGATATAAAGTAGGAAAGAACACAATTTACCGGTGACCGAATTTTCTGGATTTCCAGGGCCTTCCTTCAGGTCCGCAGATGCCCCTCCATCCGGCGTGGGCCTTGCCCGGGGTTCTGTTGCCGAGTCCAGATTCGCAGCTGTCTTTTCTTCTAGAGTCAGGAGAGTTTCTGGATTTGCGGGCGCCTTCT
    
@+F@:FF@EFFG9F9FE<88FEF8,;C6CFG@E:FGGFG@@C,6CFGFFFF9FFGGGDGGGGFFDFDF9FE,9EEE7++:,5,BFFGDG<EFGE+FEGG+:AFCF@,==FEF+8A,<FEG,?F7F@,3,8733EEG@+>EGFFCCFEC;,@7BDC,3@9C8<*,*45,2,2,2,,29:19?CDD5::2;
    AS:i:-12        XN:i:0  XM:i:4  XO:i:0  XG:i:0  NM:i:4
    MD:Z:42G51A53C15A24     YS:i:-19        YT:Z:CP
M03964:25:000000000-AKT18:1:1101:2092:11235 147 chr16 3254130 42 189M = 3254128 -191 ATATAAAGGAGGAAAGAACTCAATTTACCGGTGACCGAATGTTCTGGAGTTCCAGGGCCTTCCTTCAGGTCCGCAGAGGCCCCTCCATCCGGAGTGGGCCTTGCCCGGGGTTCTGTTGCCGAGGCCAGATTCGCAGCTGTCTTTTCCTCTAGAGTCAGGAGAATTTCTGGATTTGCGGGCGCCTGCTCC
    
))5A5655:8+8;1+1+4*+>:=+:81D8*C8@/?7GC9A70CFD;2**CFCC75;,@,EFE9C@53++++8D8>D8+ECB83,+@EGFGGGCF?@44+++F=+C:@+<GF8F=,+7CDFEAA,GEFC@+8:F8FC8FGFF8F@GCDC,9GFFF<<E<C,FFEDF6,GGGF6:::F7F7@@6CF7F@@,
    AS:i:-19        XN:i:0  XM:i:6  XO:i:0  XG:i:0  NM:i:6
    MD:Z:8T10A28T28T45T60T4 YS:i:-12        YT:Z:CP



    On 2/20/2017 9:01 PM, Colin Hercus wrote:
    Hi Jiri,

    Could you paste a few alignments from the SAM file.

    Colin

    On 21 February 2017 at 00:31, Jiri Nehyba <ji...@utexas.edu
    <mailto:ji...@utexas.edu>> wrote:

        Hi Tom,

        Thanks for your help.

        I think Bowtie2 is not changing base qualities. To verify that I
        extracted from Bowtie2 bam file back the fastqs (bedtools
        bamtofastq)
        and looked base scores in FastQC - they look the same as before
        alignment. Bowtie2 is assigning alignment quality scores (bam
        fifth
        column) and those are mostly perfect (151364 from 158220
        bam/sam lines
        have score 42).

        mpileup of samtools is changing the qualities. Below is one
        line from
        mpileup file (samtools mpileup -Q 0 -d 1000000 -f hg38.fa
        PREFIX.bam >
        PREFIX.pileup) . I folded long fifth and sixth column for better
        readibility. This is the position where the reads have C
        instead of T
        that is in reference. You might see about half of the bases have
        qualities higher than 0 (!), most frequent quality is m that
        would
        correspond to 109-33=76 on Illumina 1.8+ scale. Now original
        qualities
        both in fastqs and in bam/sam file don't have zeroes and the
        most common
        quality is G that is 38 on Illumina 1.8+ scale (lowest I can
        see just by
        looking at random places in bam file is + at the end of reads
        that is
        quality 10).


        Jiri Nehyba

        chr16    3243407    T    928
        
CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC
        
CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC.CCCCCCCCCCCC
        
CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC
        
CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC
        
CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCACCC
        
CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC.CCCCCCCCCCCCCCCcccccccccccccccc
        
cccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc
        
cccccccccccccccccccccccccccccccccccccccccccccccccccc,ccccccccccccccccccccccccccc
        
cccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc
        
cccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc
        
cccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccacccccccccccccccccc
        cccccccccccccccccccccccccccccccccccccccccccccccc
        
mhmmmmklgmlmmlmmmmmlmmmmmmmimlmmmljmml_mmmmm\llmmRkmmkjm_mmimmmlmmkmmlmmkmmfllmm
        
m`mmlmmmmmmm[m_mmmbkkmimmmmemmmRmmmkiml`glmlmmmmhi`_mm]gmmmbmkll]emLlkmmmmmkchgi
        
jmlmlkm_ilmmmmmmmmmikmXjmhjmm\jjjm`llmmimZmmh`mmmmmllRmjkmkmmkmllmmmmmmmmmmmmm[m
        
l^mmmmlmmlmhmmmmmmmmmlmmmmlmmYmmiYmmmjmmmmkmmjImmmkmmmmmgmmmklmbimmlmkmmmmmlmmim
        
emmmmmlmmmlmmmmmmmmmmmmmmkimmmkhmmjlGlhmllmmmmllmm[mmmgmeimimm_bmmkmQmamjmmlmmmf
        
mmhimmmmmlmmmmimmmml_mmjmmmmmlmmlmmmmimhemhR_^mm)mmjlmmmmkmmmm`m!!!!!!!!!!!!!!!!
        
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
        
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
        
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
        
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
        
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
        !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!


        On 2/20/2017 6:38 AM, Thomas W. Blackwell wrote:
        >
        > I think this is a bowtie2 question, not a samtools
        question. Why is
        > bowtie2 setting those base call qualities to zero ?
        >
        >                              -  tom blackwell  -
        >
        > On Sun, 19 Feb 2017, Jiri Nehyba wrote:
        >
        >> Hi,
        >>
        >> I would like to ask for help with mutation calling using
        >> samtools-bcftools. Specifically my problem is that I am
        loosing
        >> (almost) all my reverse bases and mutations are called only on
        >> forward bases (reads).
        >>
        >> I have installed last version of samtools and bcftools
        (1.3.1).
        >>
        >> I have paired fastqs from amplicon panel libraries
        sequenced on
        >> Illumina MiSeq. I cut off the primer sequences using Cutadapt,
        >> aligned reads to hg38 genome with Bowtie2 (paired
        alignment), sorted
        >> and indexed bam file with samtools and then I used
        following command:
        >>
        >> samtools mpileup -u -v -d 1000000 -f hg38.fa PREFIX.bam |
        bcftools
        >> call -c -v
        >>> PREFIX.vcf
        >>
        >> Resulting vcf file looks like this (showing just three
        rows and only
        >> some of the fields)
        >>
        >> chr16    3243407    .    T    C 221.999    .    DP=928; . . .
        >> ;DP4=1,0,462,0;MQ=42;FQ=-281.989;PV4=1,1,0.454462,1 GT:PL
        >> 1/1:255,255,0
        >> chr16    3243888    .    C    T 221.999    .    DP=2982; . . .
        >> ;DP4=2,0,1486,2;MQ=42;FQ=-281.989;PV4=1,0.458362,0.4298,1
        GT:PL
        >> 1/1:255,255,0
        >> chr16    3243922    .    A    T 221.999    .    DP=2982; . . .
        >>
        ;DP4=1,0,1486,4;MQ=42;FQ=-281.989;PV4=1,0.338485,0.450054,1 GT:PL
        >> 1/1:255,255,0
        >>
        >> What I don't like is the DP4 field that suggests extreme
        strand bias.
        >>
        >> I tried to find out why are those reverse bases discarded
        - there is
        >> no reason for generally lower quality score - amplicons
        are ligated
        >> randomly in both orientations and I am getting both sides
        of each
        >> amplicon in R1 and R2 reads.
        >>
        >> The only thing that prevents the "loss" of the bases is
        setting the Q
        >> to 0, like that:
        >>
        >> samtools mpileup -u -v -Q 0 -d 1000000 -f hg38.fa PREFIX.bam |
        >> bcftools call -c -v > PREFIX.vcf
        >>
        >> Result:
        >>
        >> chr16    3243407    .    T    C 221.999    .    DP=928; . . .
        >> ;DP4=2,1,462,463;MQ=42;FQ=-281.989;PV4=1,1,0.419714,1 GT:PL
        >> 1/1:255,255,0
        >> chr16    3243888    .    C    T 221.999    .    DP=2982; . . .
        >>
        ;DP4=2,2,1489,1489;MQ=42;FQ=-281.989;PV4=1,0.493227,0.40081,1
        GT:PL
        >> 1/1:255,255,0
        >> chr16    3243922    .    A    T 221.999    .    DP=2982; . . .
        >> ;DP4=4,3,1487,1488;MQ=42;FQ=-281.989;PV4=1,1,1,1   GT:PL
        1/1:255,255,0
        >>
        >> If I set Q to more than 0, for example 1 I will again
        loose almost
        >> all reverse bases.
        >>
        >> Finally, a look at mpileup file obtained by this command:
        samtools
        >> mpileup -Q 0 -d 1000000 -f hg38.fa PREFIX.bam > PREFIX.pileup
        >>
        >> I see that half of the bases is getting score ! that is 0  :
        >>
        >>
        >>
        >> Thank you for your help,
        >>
        >> Jiri
        >>


        
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