Restriction fragment length polymorphisms in P- and R-segments. The figure shows two representative blots. Genomic DNA of E. tenella strains Houghton (H), Weybridge (Wey), or Wisconsin (Wis) was digested with the indicated restriction enzymes, electrophoresed, blotted, and hybridized with radiolabeled probes for P- or R-segment sequences (probe names at top). (A) Shows no size polymorphism between the three strains in the XhoI or HindIII fragments detected by probe Pa; (B) shows a size polymorphism in the HindIII fragment detected by probe Rb.