Abstract
The random addition of "N nucleotides" by terminal deoxynucleotidyltransferase (TdT) is an important component of the diversity of T-cell receptor genes. We have investigated the expression of TdT during thymocyte differentiation and thymus ontogeny. TdT gene transcripts are confined to immature thymocytes of the cortex, being down-regulated concomitantly with recombination-activating gene transcripts after positive selection of mature medullary T cells. According to in situ hybridization, TdT RNA is absent from the neonatal thymus, but it appears 3 to 5 days after birth, just before the appearance of significant N-region diversity in T-cell receptor junctional sequences but clearly after the thymus attains competence at clonal deletion.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Aging / immunology
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Aging / physiology*
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Animals
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Animals, Newborn
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Base Sequence
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Cell Differentiation
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DNA Nucleotidylexotransferase / genetics
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Exons
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Gene Expression Regulation
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Genetic Variation*
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Heart / growth & development*
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Homeodomain Proteins*
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Mice
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Mice, Inbred Strains
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Molecular Sequence Data
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Oligodeoxyribonucleotides
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Polymerase Chain Reaction / methods
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Proteins / genetics
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RNA, Messenger / analysis
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RNA, Messenger / genetics
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Receptors, Antigen, T-Cell / genetics*
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T-Lymphocytes / cytology
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T-Lymphocytes / immunology*
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Thymus Gland / growth & development*
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Thymus Gland / immunology*
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Transcription, Genetic
Substances
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Homeodomain Proteins
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Oligodeoxyribonucleotides
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Proteins
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RNA, Messenger
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Receptors, Antigen, T-Cell
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RAG-1 protein
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DNA Nucleotidylexotransferase