Final answer:
Unproductive rearrangement between Valpha and Jalpha segments cannot be rescued by a second rearrangement.
Step-by-step explanation:
During the rearrangement of alpha:beta TCRs, unproductive rearrangement between Valpha and Jalpha can not be rescued by a second rearrangement between upstream Valpha and downstream Jalpha segments.
The rearrangement of the TCR genes is random and cannot be corrected if it results in an unproductive rearrangement. The T cells that undergo these unproductive rearrangements are usually eliminated through negative selection during their development in the thymus.