Hi all,

I run the code below to assemble gene expression from aligned reads:

samtools view MT1/Tophat_Out/accepted_hits.sorted.bam | python -m
HTSeq.scripts.count -q -s no - ~/Indexes/Mus_musculus/UCSC/mm10/Genes/genes.gtf > MT1/MT1.count.txt

Then I got this error message:

Error occurred when reading beginning of SAM/BAM file. file has no sequences defined (mode='r') - is it SAM/BAM format? Consider opening with check_sq=False [Exception type: ValueError, raised in libcalignmentfile.pyx:1000]

samtools view -h MT1/Tophat_Out/accepted_hits.sorted.bam

@HD VN:1.0  SO:coordinate  
@SQ SN:1    LN:195471971  
@SQ SN:10   LN:130694993  
@SQ SN:11   LN:122082543  
@SQ SN:12   LN:120129022  
@SQ SN:13   LN:120421639  
@SQ SN:14   LN:124902244  
@SQ SN:15   LN:104043685  
@SQ SN:16   LN:98207768  
@SQ SN:17   LN:94987271  
@SQ SN:18   LN:90702639  
@SQ SN:19   LN:61431566  
@SQ SN:2    LN:182113224  
@SQ SN:3    LN:160039680  
@SQ SN:4    LN:156508116  
@SQ SN:5    LN:151834684  
@SQ SN:6    LN:149736546  
@SQ SN:7    LN:145441459  
@SQ SN:8    LN:129401213  
@SQ SN:9    LN:124595110  
@SQ SN:MT   LN:16299  
@SQ SN:X    LN:171031299  
@SQ SN:Y    LN:91744698  
@PG ID:TopHat   VN:2.1.1    CL:/gpfs2/global/tophat-2.1.1.Linux_x86_64/tophat -r 200 -p 8 -o /gpfs2/home/user/protocol_1/data/MT1/Tophat_Out -G /gpfs2/home/user/ncbi-genomes-2022-09-07/Mus_musculus/Ensembl/GRCm38/Annotation/Genes/genes.gtf /gpfs2/home/user/ncbi-genomes-2022-09-07/Mus_musculus/Ensembl/GRCm38/Sequence/Bowtie2Index/genome /gpfs2/home/user/protocol_1/data/Fastq/Trim_MT1_1.fastq /gpfs2/home/user/protocol_1/data/Fastq/Trim_MT1_2.fastq  
@PG ID:samtools PN:samtools PP:TopHat   VN:1.12 CL:samtools view -h /gpfs2/home/user/protocol_1/data/MT1/Tophat_Out/accepted_hits.sorted.bam  
SRR213132.1920910.2 385 1   3155596 0   80M =   890971485941625 AATTCAACTAGAAAGTTACCTACCAAGTACTAATTAGAATTATAAAGTCAGAGTCTGCAGCTCCAGGCCTTTCAGTTAGT    A>CE+<4<B<<?EHHB?:?AA9<AFGC:ED@GDF*:**:B<FCII>B??DGE@/?BFGBBDADF;@EDDACECC=A?;;7    AS:i:-2 XN:i:0  XM:i:1  XO:i:0  XG:i:0  NM:i:1  MD:Z:37C42  YT:Z:UU NH:i:20 CC:Z:=  CP:i:7949540    HI:i:0  
SRR213132.34347266.1    113 1   3593111 50  80M 19  3806813GAACTCCCTAGTTAGAACCATGACTTGGGTGTGAAAGCCCTTGCCCTAGGAGTGAAAAGTCCTCACACCTGGCTTCTAAGC?5?;?>CDEFDFCCDHHHHHHIIIGHGHGFEGIIGBFIIIJIHFD<JIIHGIJJJJJGGHCHEFIHIIIJJJJJJJHHHAS:i:-5  XN:i:0  XM:i:1  XO:i:0  XG:i:0  NM:i:1  MD:Z:60T19  YT:Z:UU XS:A:-  NH:i:1  

...

Would you please what I need to do to fix this? Thanks a lot!