We thank Mengjing Xu (research fellow), Yilin Jin (research fellow), and Shuke Nie (doctoral student) for helping raise the animals.

Role of Funding Source

This work was supported by the National Natural Science Foundation of China (NSFC-31171681 and NSFC-81472978) and the earmarked fund for Modern Agro-industry Technology Research System (CARS-17), China. The funding source had no further role in the study design, in the collection, analysis and interpretation of data; in the writing of the manuscript; and in the decision to submit the paper for publication.

Contributors

Author Hui Gao designed and wrote a first draft of the paper. Peipei Yan and Hao Huang carried out all the experiments. Shun Zhang and Fenghong Huang undertook the statistical analysis and created the figures. Taoping Sun, Sijing Chen, and Qianchun Deng performed dissection procedures. Qingde Huang managed the literature searches. Keqiang Ye assisted with the preparation and proof-reading of the manuscript. Jiqu Xu and Liegang Liu contributed to the design of the study, reviewed the manuscript, and contributed to the final version. All authors contributed to and have approved the final manuscript.

Conflict of Interest

The authors can identify no potential conflicts of interest.