Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
The double-headed arrows (left side) indicate Ac elements, while the single-headed arrows (right side) indicate fAc. The red × symbol indicates the junction of the two re-replicated segments in the insertion. Other symbols have the same meaning as in Figure 1 and Figure 2A.
