Mice lacking TdT: mature animals with an immature lymphocyte repertoire.
In adult animals, template-independent (or N) nucleotides are frequently added during the rearrangement of variable (V), diversity (D), and joining (J) segments of lymphocyte receptor genes, greatly enhancing junctional diversity. Receptor genes from adult mice carrying a mutation in the terminal deoxynucleotidyl transferase (TdT) gene have few N nucleotides, providing proof that this enzyme is essential for creating diversity. Unlike those from normal adults, receptor genes from adult mutant mice show extensive evidence of homology-directed recombination, suggesting that TdT blocks this process. Thus, switch-on of the TdT gene during the first week after birth provokes an even greater expansion of lymphocyte receptor diversity than had previously been thought.
Gilfillan
S
S
Laboratoire de Génétique Moléculaire des Eucaryotes du CNRS, Institut de Chimie Biologique, Strasbourg, France.
Dierich
A
A
Lemeur
M
M
Benoist
C
C
Mathis
D
D
D000818:Animals; D001483:Base Sequence; D004253:DNA Nucleotidylexotransferase / Q000235:genetics / Q000378:metabolism*; D015322:Gene Rearrangement, B-Lymphocyte; D015329:Gene Rearrangement, T-Lymphocyte; D005803:Genes, Immunoglobulin; D007133:Immunoglobulin Joining Region / Q000235:genetics; D007135:Immunoglobulin Variable Region / Q000235:genetics; D008214:Lymphocytes / Q000276:immunology*; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D009154:Mutation; D009711:Nucleotides / Q000378:metabolism*; D011948:Receptors, Antigen, T-Cell / Q000235:genetics*; D011995:Recombination, Genetic
D007133:Immunoglobulin Joining Region; D007135:Immunoglobulin Variable Region; D009711:Nucleotides; D011948:Receptors, Antigen, T-Cell; D004253:DNA Nucleotidylexotransferase