Comparing the transcriptome of SP cells with that of non-SP cells in rainbow trout

In rainbow trout, type A spermatogonia can be split into SP cells and non-SP cells by the ability to exclude Hoechst 33342 dye (H33342). The H33342 fluorescence of SP cells are lower than that of non-SP cells, after H33342 staining. To investigate whether SP cells were transcriptomically distinct from non-SP cells, we compared the transcriptome of these cells. We used fluorescence-activated cell sorting (FACS) to isolate SP cells and non-SP cells from the type A spermatogonia in rainbow trout. To compensate unavailability of genetically uniform rainbow trout in independent sampling, SP cells and non-SP cells were collected at 3 times from 3 different parental fish groups. This experimental design allowed us to estimate effects specific to each parental fish genotype on mRNA expression in SP cells by a statistical modeling and to exclude the effects in subsequent analysis.