Figure 4.

Linkage of class Ia and class IIα and -β genes in the second nurse shark family of 39 offspring. The designations of diploid groupings and alleles are the same as in Fig. 3. Note that the class Ia leader hybridizations are much more discriminatory on this blot and are designated as U or L according to which band cosegregates with the U/L bands revealed with the α1 domain probe. The restriction enzymes used and the approximate sizes of the bands are the same as in Fig. 3.