Nucleic Acids Research, 2006, Vol. 34, No. 22 6701 Figure 3. Immunogold localization of SFM and 2TMFM in the transformed lines pHL-SFM and pHL-2TMFM. Thin sections of late trophozoites and schizonts from pHL-SFM line (a–f) and pHL-2TMFM line (g–l) were probed with an anti-c-myc mAb and revealed by 6 nm gold-labeled anti-mouse IgG. Gold particles were associated with Maurer’s clefts (a, g and h) or the erythrocyte surface (b–f, h, i, k and l). Some particles were associated with knobs (c, f, i and l). Bar, 0.25 mm. within a locus that is present, as either extended or frag- mented versions, as 13 copies in the 3D7 isolate genome. The extended versions share 36 Kb or more of sequence simi- larity, including >95% nt sequence identity spanning 15 Kb of sequence (Figure 6A); and almost 100% identity within numerous stretches >1 Kb, particularly for an alignment of the extended loci of the Pfmc-2TM genes PFF1525c, PFF0060w, PF11_0025 and PF10_0390 (the topmost four loci in Figure 6A). The loci identiﬁed as truncated versions (e.g. the loci containing PFA0680c, MAL7P1.58 or PFB0960c) might have additional sequence identities that were not recognized by the ClustalW alignment program, perhaps due to large deletions or insertions. It is possible that the ampliﬁed sub-telomeric loci are identical to one or more ‘sub-telomeric blocks’ described in the P.falciparum genome sequence manuscript [e.g. SB-4 or SB-5; see Figure 2 of Ref. (33)]. The conservation of sequences ﬂanking Pfmc-2TM genes is reminiscent of the subsets of var genes which share substantial conserved ﬂanking nucleotide sequences (34), although the var gene loci do not extend to the length, nor to the degree of the nucleotide conservation of the Pfmc-2TM loci.