Gene expression profiling of granule cells and Purkinje cells in the zebrafish cerebellum.

The structure of the neural circuitry of the cerebellum, which functions in some types of motor learning and coordination, is generally conserved among vertebrates. However, some cerebellar features are species specific. It is not clear which genes are involved in forming these conserved and species-specific structures and functions.

Separate domains of AID are required for somatic hypermutation and class-switch recombination.

Activation-induced cytidine deaminase (AID) is essential for class-switch recombination (CSR) and somatic hypermutation (SHM). Mutants with changes in the C-terminal region of AID retain SHM but lose CSR activity. Here we describe five mutants with alterations in the N-terminal region of AID that caused selective deficiency in SHM but retained CSR, suggesting that the CSR and SHM activities of AID may dissociate via interaction of CSR- or SHM-specific cofactors with different domains of AID.