Structure prediction for a dicistronic tRNA-C/D box sRNA and a H/ACA box sRNA. (a) The most abundant C/D box sRNA, sRNA8, is located immediately downstream of tRNAVal(TAC). The tRNA secondary structure was obtained with tRNA-Scan-SE  and a possible C/D box sRNA8 secondary structure was computed with mfold . The box C/D and box C'/D' elements and the proposed RNase Z cleavage site are indicated. (b) Possible secondary structure (mfold ) for the single identified H/ACA box sRNA. Two ACA motifs and two identical k-turn bulges with potential GA-GA pairs are indicated.