Identification and characterization of core elements for SD13M. (A) MUSCLE analysis of identified core elements. The radial pattern with branches of similar length indicates that the levels of difference between the 60 types of core elements are similar. (B) Map of sequences homologous to each core element on SD13M. The locations and directions of homologous sequences for each core element are mapped on the horizontal line. Red and blue diamonds indicate positive and negative orientations, respectively.