sentence: In addition to the RVD-defined base-preference of TALE-likes , the N-terminal regions ( NTRs ) of TALEs include sequence-degenerate repeat units known to exert a fixed base preference for thymine ( T ) , while the homologous region in RipTALs specifies a preference for guanine ( G ) ( Gao et al ., 2012 ; de Lange et al ., 2013 ) .