RNA-seq was carried out as described previously [34 (link)]. Total RNA from seminiferous tubules from one animal was extracted using 1 ml TRIzol reagent (Life Technologies). Quantity of the isolated total RNA was determined by spectrophotometric measurement using the NanoDrop device. The quality of the RNA was determined using standard 1% agarose gel electrophoresis. For the RT-PCR and quantitative RT-PCR (qRT-PCR), the RNA was treated with RQ1 (RNA Qualified) RNase-Free DNase (Promega) as recommended. RNA-seq libraries from three wild-type and three knockout animals were prepared using Illumina's TruSeq RNA Sample Preparation Kits v2 (Illumina Inc.). Briefly, 4 μg of total RNA was poly(A)-selected, followed by generation of double-stranded cDNA. Adapters were ligated, and resulting fragments were amplified by limited number of PCR cycles. RNA-seq libraries were sequenced on HiSeq 2000 platform with 90-nucleotide coverage of each end (PE90). Over 41 million individual sequences from each library were collected with a Q20% larger than 97%.