Hello, I am relatively new to this and would like to pull out reads aligned to the mm10 genome to a particular region of interest. I first ran my fastq files in tophat to get bam files. I then ran BamToSam to get the sam files with the read sequences and alignments. I thought it would be as simple as doing a grep on the chromosome I want and looking within those results to pull out the genomic region I want however my Sam file has 21 fields per row where column 3 and column 7 both have chromosomes and I believe that columns 4 and 8 are start locations. I am not clear as to which of these would be the aligned region of the genome? Any thoughts, or advice? Here is a line from my Sam file. Also, I took the sequence and blatted it on mm10 and the 100% returned hits did not match either chromosome? Maybe I am missing something. Any thoughts would be really helpful? thanks.
D192UACXX:7:2212:12464:05542 99 chr1 3035207 50 101M = 3035303 197 GTCCTGATTATGTATCTGATCTGTTAGTCTGTATCATTTTATTAGGGAATACAGTCCATTGATATTAAGAGATATTACAGAAAAAATGATTGTTGCTTCCT CBCFFFFFHHHHHJJJJJHJJJJJJJIHIIIHIIJIJJJIJJJJJJGIJJJJJIJJJJJJIJJJJIHIHIDHIIFHIIJJJJIJHHFF7?DFFEEEEEED AS:i:0 XN:i:0 XM:i:0 XO:i:0 XG:i:0 NM:i:0 MD:Z:101 YT:Z:UU NH:i:1 XS:A:-
D192UACXX:7:2212:12464:05542 99 chr1 3035207 50 101M = 3035303 197 GTCCTGATTATGTATCTGATCTGTTAGTCTGTATCATTTTATTAGGGAATACAGTCCATTGATATTAAGAGATATTACAGAAAAAATGATTGTTGCTTCCT CBCFFFFFHHHHHJJJJJHJJJJJJJIHIIIHIIJIJJJIJJJJJJGIJJJJJIJJJJJJIJJJJIHIHIDHIIFHIIJJJJIJHHFF7?DFFEEEEEED AS:i:0 XN:i:0 XM:i:0 XO:i:0 XG:i:0 NM:i:0 MD:Z:101 YT:Z:UU NH:i:1 XS:A:-
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