RIKEN BioResource Center View Institution's Website 2 articles published in JoVE Genetics High-Resolution Comparison of Bacterial Conjugation Frequencies Masaki Shintani1,2,3, Moriya Ohkuma3, Kazuhide Kimbara1 1Applied Chemistry and Biochemical Engineering Course, Department of Engineering, Graduate School of Integrated Science and Technology, Shizuoka University, 2Department of Bioscience, Graduated School of Science and Technology, Shizuoka University, 3Japan Collection of Microorganisms, RIKEN BioResource Research Center With an aim to understand the behaviors of various bacterial conjugative DNA elements under different conditions, we describe a protocol for detecting differences in conjugation frequency, with high resolution, to estimate how efficiently the donor bacterium initiates conjugation. Biology Cryopreservation of Mouse Embryos by Ethylene Glycol-Based Vitrification Keiji Mochida1, Ayumi Hasegawa1, Kyuichi Taguma1, Atsushi Yoshiki1, Atsuo Ogura1 1RIKEN BioResource Center An ethylene glycol-based vitrification method for mouse embryos is described. It is advantageous to other methods in its simplicity and low embryonic toxicity, and therefore can be broadly applicable to many strains of mice, including inbred and gene-modified mice.