Live-cell imaging of nuclear–chromosomal dynamics in bovine in vitro fertilised embryos

• Published in: Scientific reports Vol. 8; no. 1; pp. 7460 - 9
• Main Authors: Yao, Tatsuma, Suzuki, Rie, Furuta, Natsuki, Suzuki, Yuka, Kabe, Kyoko, Tokoro, Mikiko, Sugawara, Atsushi, Yajima, Akira, Nagasawa, Tomohiro, Matoba, Satoko, Yamagata, Kazuo, Sugimura, Satoshi
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 10-05-2018; Nature Publishing Group; Nature Portfolio
• Subjects: 13; 14; 631/136/1455; 631/80/641/2002; Animals; Blastocysts; Cattle - embryology; Cattle - genetics; Cell Survival; Chromosome Aberrations; Chromosome Segregation; Cytokinesis; Cytoplasm; Embryo, Mammalian - abnormalities; Embryo, Mammalian - cytology; Embryo, Mammalian - embryology; Embryo, Mammalian - ultrastructure; Embryogenesis; Embryonic growth stage; Embryos; Female; Fertilization in Vitro; Green fluorescent protein; Green Fluorescent Proteins - analysis; Histone H2B; Humanities and Social Sciences; Light microscopy; Luminescent Proteins - analysis; Microscopy; Microscopy, Confocal - methods; mRNA; multidisciplinary; Multivariate analysis; Optical Imaging - methods; Pregnancy; Red Fluorescent Protein; Reproductive technologies; Science; Science (multidisciplinary); Tubulin
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-018-25698-w

Nuclear/chromosomal integrity is an important prerequisite for the assessment of embryo quality in artificial reproductive technology. However, lipid-rich dark cytoplasm in bovine embryos prevents its observation by visible light microscopy. We performed live-cell imaging using confocal laser microscopy that allowed long-term imaging of nuclear/chromosomal dynamics in bovine
in vitro
fertilised (IVF) embryos. We analysed the relationship between nuclear/chromosomal aberrations and
in vitro
embryonic development and morphological blastocyst quality. Three-dimensional live-cell imaging of 369 embryos injected with mRNA encoding histone H2B-mCherry and enhanced green fluorescent protein (EGFP)-α-tubulin was performed from single-cell to blastocyst stage for eight days; 17.9% reached the blastocyst stage. Abnormalities in the number of pronuclei (PN), chromosomal segregation, cytokinesis, and blastomere number at first cleavage were observed at frequencies of 48.0%, 30.6%, 8.1%, and 22.2%, respectively, and 13.0%, 6.2%, 3.3%, and 13.4%, respectively, for abnormal embryos developed into blastocysts. A multivariate analysis showed that abnormal chromosome segregation (ACS) and multiple PN correlated with delayed timing and abnormal blastomere number at first cleavage, respectively. In morphologically transferrable blastocysts, 30–40% of embryos underwent ACS and had abnormal PN. Live-cell imaging may be useful for analysing the association between nuclear/chromosomal dynamics and embryonic development in bovine embryos.