The recombination-activating gene 1 of Pleurodeles waltl (urodele amphibian) is transcribed in lymphoid tissues and in the central nervous system

The recombination-activating gene 1 (RAG1) product is required for the soma tic rearrangement of immunoglobulin and T-cell receptor genes. We cloned an d sequenced the large continuous open reading frame coding for the salamand er Pleurodeles waltl RAG1 protein. Semi-quantitative RT-PCR experiments wer e performed to quantify the expression of RAG1 in different tissues. The st rongest signal was observed in the thymus of juvenile animals, confirming t he primary lymphoid nature of that organ. Weaker expression was observed in the spleen, brain, and eyes of adults. Signals in these tissues represente d 5.5%, 4.6%, and 2.0%, respectively, of the signal detected in the thymus. Expression in brain was confirmed by in situ hybridization. Similarly, low amounts of RAG1 transcripts were previously detected in the mouse brain. M oreover, the transcription of RAG1 begins as early as the neurula stages of development. These data suggest that the RAG1 protein could play a role in the central nervous system of vertebrates.