I have been analyzing zebrafish wild-type v mutant libraries. I have three mutant microRNA libraries called mir125b-1, mir125b-2, mir125b-3, and three wild-type libraries wt-1, wt-2, wt-3 .I am using GRCz10 as a reference genome and the corresponding zebrafish genome as a GTF file for mapping. I am using HTSeq default scripts to count the total number alignments. When I mapped my alignments for both wild type and mutant libraries using Ensembl biomart Ensembl ids as a filter. I got 231 microRNA counts for both microRNA mutants and wild-type embryos. My question is should the count for mutant v wild type be different or actually the mappings are always same but what matters is the difference in alignment counts for a particular microRNA read? Like mir10a has been mapped 320509 times for mir125b-1 and 258174 for wt-1.
Any information regarding the conceptual understanding will be helpful.
Thanks for the answer. I understand the differences between wild type and mutant libraries. My question was whether with respect to microRNA discovery a mutant microRNA library will have more or less microRNAs detected with respect to wild type when mapped to an assigned annotation or the difference will lie only in the number of alignments matched which should vary between wildtype and mutants where as the actual number of alignments matched would be similar?