**5. Acknowledgments**

We thank Dr. Robb Krumlauf for pBGZ40 vector and Dr. Neal G. Copeland for the recombineering related materials including *EL250* bacterial stain. We also acknowledge Drs. Takayuki Sota, Shinichi Kohsaka, Keiji Wada, Mikio Hoshino and their lab members for discussions and encouragements. This work was supported by grants from Takeda Science Foundation, The Nakatomi Foundation and Research Foundation ITSUU Laboratory, Program for Promotion of Fundamental Studies in Health Sciences of the National Institute of Biomedical Innovation (05-32), and a Grant-in-Aid for Scientific Research from JSPS (#21500333) to T. Inoue.
