Figure 1

Southern blot. Southern blot of the PstI restriction pattern in B. atticus, using XbaI₃₅₀ (A) and the PCR-obtained 5'-end of the 18S gene (B) as hybridizing probes. Southern Blot analysis revealed that: i) XbaI₃₅₀and PstI₅₃₀ cross-hybridize, with XbaI₃₅₀being part of the PstI₅₃₀ fragment (also tested by subsequent sequencing); ii) PstI₅₃₀ is a tandemly repeated sequence (* = PstI₅₃₀ dimer; ** = PstI₅₃₀ trimer), as also supported by XbaI₃₅₀restriction pattern (not shown); iii) 18S PCR probe and XbaI₃₅₀ hybridize with PstI₅₅₀₀, so they are associated; iv) the PstI₅₅₀₀ band is the rDNA cluster, since it hybridizes to the 18S probe (also checked by subsequent sequencing).