BÁO CÁO KHOA HỌC VỀ NGHIÊN CỨU VÀ GIẢNG DẠY SINH HỌC Ở VIỆT NAM - HỘI NGHỊ KHOA HỌC QUỐC GIA LẦN THỨ 5 DOI: 10.15625/vap.2022.0073 INCREASE HISTONE ACETYLATION DURING THE FIRST MITOTIC CELL CYCLE IMPROVES PREIMPLANTATION DEVELOPMENT AND THE QUALITY OF MOUSE EMBRYOS GENERATED BY ROUND SPERMATID INJECTION (ROSI) Pham Xuan Anh 1,# , Nguyen Nhat Thinh 1,# , Tang Kim Hoang Van 1 , Pham Truong Duy 1 , Pham Quoc Dinh 1 , Pham Minh Chien 1 , Bui Hong Thuy 1 , Nguyen Van Thuan 1,* Abstract. This study examined the effects of Scriptaid, a histone deacetylase inhibitor (HDAC) during the first mitotic cell cycle on preimplantation development of mouse embryos generated by injection of round spermatid into mature oocytes. In the first experiment, we treated ROSI embryo with 0, 50, 250, 500, 1.000 nM Scriptaid for 16 hours after injection and activation. We found the intensity of histone acetylation and diameter of ROSI male pronucleus are proportional to the increase of concentration of Scriptaid; however, the rate of ROSI embryo development to blastocyst was highest at 250 nM Scriptaid (51.6 %) compared with the other concentrations (19.4 %, 34.4 %, 35.3 %, and 8.6 %, respectively). In the second experiment, 250 nM Scriptaid is used to test optimal timing (6, 10, 16 hours) for Scriptaid treatment on preimplantation development of ROSI embryos. The results showed that the 10-hour to 16-hour treatment groups resulted in the highest development of ROSI embryos to the blastocyst stage (56 % and 57 %, P < 0.05) compared with 6-hour group (23 %). In conclusion, increasing histone acetylation at concentration of 250 nM Scriptaid with 10-hour treatment increased the intensity of histone acetylation and decondensation of the male DNA, finally increase the rate of ROSI embryos developing to blastocyst and blastocyst quality. Keywords: Histone acetylation, histone deacetylase inhibitor, mouse, preimplantation development, pronuclear formation, ROSI, round spermatid, Scriptaid. 1. INTRODUCTION Previous studies have demonstrated that using round spermatids after completion of second meiosis process injecting into mature oocyte can produce a fertilized embryo; some cases can produce a full-term development (Ogura et al., 1994; Yanagimachi, 2005; Hirabayashi et al., 2009). Until recently, development rate of ROSI embryos to full-term development is still significantly lower than that of fertilized embryo generated by mature spermatozoa for many reasons (Kimura et al., 1994; Kishigami et al., 2004; Kishigami et al., 2004b; Yanagimachi, 2005), typically due to abnormal DNA hypermethylation of 1 International University, Vietnam National University, Ho Chi Minh City # Equally contributed to this work * Email: nvthuan@hcmiu.edu.vn