Camelia Tulcan2, Ioan Hutu2, Calin Mircu2 GENE EXPRESSION PATTERNS DURING IN VITRO DIFFERENTIATION OF BOVINE SKELETAL MUSCLE Oana Isabella Gavriliuc1, Virgil Paunescu1, Daniela Elena Ilie2, Cornelia Milovanov2, Camelia Tulcan2, Ioan Hutu2, Calin Mircu2 1 Dept. of Immunology, 'Victor Babes' University of Medicine and Pharmacy Timisoara, Romania 2 Banat University of Agricultural Sciences and Veterinary Medicine Timisoara, Romania Background Methods Differentiation of skeletal muscle is a multistep process assigned to a small population of muscle progenitor/stem cells and controlled by the interplay of regulatory transcription factors and cues from the culture medium. We established proliferating­ cell cultures from adult and newborn bovine skeletal muscle tissue and induced their in vitro differentiation into myotubes, using a serum-free medium formulation or media with horse serum. Gene expression pattern of bovine myogenic regulatory factors myf5, MyoD1, Pax7, myogenin and pluripotency-associated factors Oct4 and Nanog was determined by quantitative real-time PCR and correlated with the degree of myotube formation. Results Younger cells derived from newborn animals express pluripotency transcription factors at a higher level than cells derived from adult animals, whereas adult cells express some myogenic differentiation-associated activated factors. DM2 medium, which was also responsible for the best myogenic differention, induced downregulation of myogenic activating factors compared to the control, but higher than the other media. Diff. medium 1: DMEM/F12, 5%Horse serum 1, 10 ng/mL bFGF Diff. medium 2: DMEM/F12, 5%Horse serum 2, 10 ng/mL bFGF Diff. medium 3: 3:1 L15: M199, B27, 10 ng/mL bFGF Best differentiation, assessed by number of myotubes obtained, was observed for the second differentiation medium, with in-house collected horse serum and FGF. Conclusions Acknowledgements An efficient, sustained, myogenic conversion requires a continuous expression of intermediate levels of myogenic activation factors, but also that of pluripotency transcription factors. This work was supported by human resource postdoctoral program POSDRU/89/1.5/S/62371 and applied research partnership grant PN II PCCA 120/2012. European Biotechnology Congress, Bratislava, Slovakia 16-18 May, 2013 UMFVBT ‘VICTOR BABES’ UNIVERSITY OF MEDICINE AND PHARMACY TIMISOARA USAMVBT BANAT UNIVERSITY OF AGRICULTURAL SCIENCES AND VETERINARY MEDICINE