Simple and rapid determination of homozygous transgenic mice via in vivo fluorescence imaging.

// Xiaolin Lin 1, * , Junshuang Jia 1, * , Yujuan Qin 1, * , Xia Lin 1, * , Wei Li 1 , Gaofang Xiao 1 , Yanqing Li 1 , Raoying Xie 1 , Hailu Huang 1 , Lin Zhong 1 , Qinghong Wu 3 , Wanshan Wang 3 , Wenhua Huang 4 , Kaitai Yao 1 , Dong Xiao 1, 3 , Yan Sun 2 1 Cancer Research Institute, Southern Medical University, Guangzhou, China 2 Joint Program in Transfusion Medicine, Children’s Hospital Boston, Harvard Medical School, Boston, Massachusetts, USA 3 Institute of Comparative Medicine & Laboratory Animal Center, Southern Medical University, Guangzhou, China 4 Department of Anatomy, Guangdong Provincial Key Laboratory of Construction and Detection in Tissue Engineering, School of Basic Medical Science, Southern Medical University, Guangzhou, China * These authors have contributed equally to this work Correspondence to: Yan Sun, e-mail: suny528@gmail.com Dong Xiao, e-mail: Xiao_d@hotmail.com Kaitai Yao, e-mail: yao.kaitai@hotmail.com Keywords: transgenic mice, fluorescence reporter gene, in vivo qualitative and quantitative fluorescence imaging, homozygote Received: June 26, 2015      Accepted: October 02, 2015      Published: October 12, 2015 ABSTRACT Setting up breeding programs for transgenic mouse strains require to distinguish homozygous from the heterozygous transgenic animals. The combinational use of the fluorescence reporter transgene and small animal in-vivo imaging system might allow us to rapidly and visually determine the transgenic mice homozygous for transgene(s) by the in vivo fluorescence imaging. RLG, RCLG or Rm17LG transgenic mice ubiquitously express red fluorescent protein (RFP). To identify homozygous RLG transgenic mice, whole-body fluorescence imaging for all of newborn F2-generation littermates produced by mating of RFP-positive heterozygous transgenic mice (F1-generation) derived from the same transgenic founder was performed. Subsequently, the immediate data analysis of the in vivo fluorescence imaging was carried out, which greatly facilitated us to rapidly and readily distinguish RLG transgenic individual(s) with strong fluorescence from the rest of F2-generation littermates, followed by further determining this/these RLG individual(s) showing strong fluorescence to be homozygous, as strongly confirmed by mouse mating. Additionally, homozygous RCLG or Rm17LG transgenic mice were also rapidly and precisely distinguished by the above-mentioned optical approach. This approach allowed us within the shortest time period to obtain 10, 8 and 2 transgenic mice homozygous for RLG, RCLG and Rm17LG transgene, respectively, as verified by mouse mating, indicating the practicality and reliability of this optical method. Taken together, our findings fully demonstrate that the in vivo fluorescence imaging offers a visual, rapid and reliable alternative method to the traditional approaches (i.e., mouse mating and real-time quantitative PCR) in identifying homozygous transgenic mice harboring fluorescence reporter transgene under the control of a ubiquitous promoter in the situation mentioned in this study.