AUTHOR CONTRIBUTIONS
C.X., Y.X.X., Y.Q. and C.X.Z. designed the study;
X.C.C. and C.J.B. collected the samples;
W.Q., S.P. and W.R.R. analyzed the results;
W.Q. and Y.Q. wrote the manuscript;
W.L.X., S.P. and L.Y. revised the manuscript;
all authors read and approved the final version of the manuscript.