A fluorescent reporter strain for sexing at the preimplantation embryos

RIKEN BRC July 2023
Mouse of the Month
A fluorescent reporter strain
for sexing at the preimplantation embryos

B6;129B6-Tg(CAG-Su9/tdTomato/T2A/Puro)1GAitn (RBRC11535)


Blastocyst stage embryos (left) and pups (right) obtained by crossing X-GFP/Y-mtRFP mice with wild-type female mice. RFP-positive males (*) and GFP-positive females can be distinguished at the preimplantation stage.


Y-mtRFP mice (RBRC11535) have a transgene (CAG-Su9-tdTomato-T2A-Puror) inserted between exon 1 and 2 of the Ddx3y gene on the Y chromosome in the opposite direction to the Ddx3y gene. Y-mtRFP mice ubiquitously express red fluorescent tdTomato, which is distinguishable from green fluorescent protein (GFP), on the Y chromosome. In addition, the inclusion of a mitochondrial locating signal (Su9) into N-terminal of tdTomato avoids a postnatal lethal phenotype that may be due to the cytotoxic properties of tdTomato. It was reported that almost half of the fertilized eggs collected from Y-mtRFP male mice crossed with wild-type female mice showed red fluorescent signals at the pre-implantation stage. This indicates that XY eggs were recognized as tdTomato-positive embryos at the preimplantation stage. Furthermore, it is also reported that X-GFP/Y-mtRFP by mating Y-mtRFP male mice with X-GFP female mice (RBRC02032), in which GFP is ubiquitously expressed on X chromosomes, allow clearer sexing at the preimplantation embryos. The Y-mtRFP strain is a useful fluorescent reporter tool for a wide range of sex chromosome-related research.


Keywords : sex chromosome, preimplantation embryo, tdTomato, sexing, mitochondria
Depositor : Ayako Isotani, Ph.D. (Nara Institute of Science and Technology)
Strain name : B6;129B6-Tg(CAG-Su9/tdTomato/T2A/Puro)1GAitn
RBRC No. : RBRC11535
Reference : [1] Hirata W, Tomoda T, Yuri S, Isotani A.
Generation of the Y-chromosome linked red fluorescent protein transgenic mouse model and sexing at the preimplantation stage.
Exp Anim. 2022 Feb 9;71(1):82-89.
Related mouse resource : B6;B6C3-Tg(CAG/Acr-EGFP)CX-FM139Osb (RBRC02032)


July 2023
Saori Mizuno, Ph.D.
Contact: Experimental Animal Division, RIKEN BioResource Research Center (animal.brc@riken.jp)
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