ABSTRACT: Purpose: RNA-seq method was applied to select genes expressed in feed conversion in pigs and pinpointed genes potentially associated with this feature. Methods: The whole pituitary samples were collected from 16 Puławska pigs (8 pigs per two groups - with high and low feed conversion) maintained at the same environmental and feeding condition. The RNA-seq analysis was performed in 90 single-end cycles on HiScanSQ platform (Illumina) and differentially expressed genes (DEGs) were determined using Deseq2 software. Validation was performed for 10 randomly selected genes using real-time PCR method. Results: The study showed that in pigs characterized by better feed conversion 274 genes were differentially expressed. Genes showed decreased expression encode proteins associated with cholesterol metabolism (APOA1, CH25H, APOE) and regulation of hormone levels (POMC, CTSZ, ADM, AGTR1, SOX8, AGT, CPT1, APOA1, GJA1, MYRIP, CYP1B1, NR1D1). Four genes showed over the 10-fold decrease of expression (CRYM, ISM1 and WNK4), where the CRYM protein binds thyroid hormone for regulatory and developmental roles and WNK4 regulates the balance between NaCl reabsorption and K(+) secretion. In turn, genes showed an increase of expression in the pituitary of pigs having better feed conversion encode proteins were related to cellular response to corticotropin-releasing hormone stimulus (NR4A1, NR4A2, NR4A3) and regulation of type B pancreatic cell proliferation (BIRC5, NR4A3, NR4A1). Conclusions: The present study indicates new genes potentially related to feed conversion, which is one of the most economically important traits in pig breeding. The selected genes should be investigated in future in the terms of their association with fattening traits. The study was financed from funds of the project -BIOSTRATEG, the decision number BIOSTRATEG2/297267/14/NCBR/2016.
