Jα repertoires of TEA and Jα49 promoter-deleted mice. Vα8 to Cα RT-PCR products obtained from thymocytes of 4-5 week old ΔJ49, ΔTEAΔJ49, and Δ5′ mice, from thymocytes of 2-5 week old ΔTEA mice, and from thymocytes of age-matched wild-type littermates, were fractionated on agarose gels and immobilized to nylon filters. Jα usage was evaluated by hybridization with 32P-labeled Jα and Cα oligonucleotide probes. Relative Jα usage was calculated as (Jα signal for mutant / Cα signal for mutant) / (Jα signal for wild-type / Cα signal for wild-type). The dashed line indicates wild-type Jα usage (frequency=1). Results represent the mean ± SEM of 4-8 determinations.