South western assay with Giardia S/MARs. Nuclear Matrix was isolated from Giardia cells and the different fractions were separated on a SDS-PAGE (Panel A lane 6). The other fractions are cytoplasm (lane 1)Extract after DNAse treatment (lane 2); extract after treatment with 50 mM NaCl (Lane3) and extract after treatment with 1.6 M salt (Lane 4 and 5). Panel B shows the southwestern hybridization of the nuclear farctions of Giardia separated in a SDS-PAGE, with the different probes. 8 of the 14 predicted Giardia S/MARs are able to bind to nuclear matrix. (Lane5; 4B-I) in all the panels. Only GlSMAR10 (4b lane 4)) shows binding to 1.6 M salt extract along with nuclear matrix proteins. All others GlSMAR7 (panel a); GlSMAR16 (panel c); GlSMAR20 (panel d); GlSMAR22 (panel e); GlSMAR26 (panel f) GlSMAR58 (panel g) and GlSMAR66 (panel h) bind only to nuclear matrix proteins. Panel I is a negative control probed with linear digest of pUC19 DNA, which shows no binding to nuclear matrix or high salt extract.