From the reported P. marinus genome database we identified two major types of SL RNA genes: PmaSLRNA-L or L-type, and PmaSLRNA-S or S-type ( Figure 1A) , with the SL exons corresponding to the two SL sequences found previously in pcna and cyclins [14] . These sequences were similar to DinoSL ( Figure 1B ). For the L-type, we identified seven sequences (Table 3) , and all but one (AAXJ01000089, containing two units of SL RNA) are 1-1.8 kb in length containing a single SL RNA gene. For the S-type, 42 sequences were identified with lengths ranging 1 to .14 kb (Table 4) ; of these, some were arrayed as tandem repeats or as a single unit clustered with both or either of the U2 and U4 snRNA genes downstream of the SL RNA gene; others were single or 2-unit tandem-repeat sequences not associated with U2 or U4 snRNA genes ( Table 4 ).