Ribosomal and chromosomal protein cDNA clones of Xenopus laevis thymus isolated with differential screening

1. Xenopus laevis is an excellent system for the study of the evolution and ontogeny of the immune system. But since only immunoglobulin genes have been isolated from this species, we undertook to isolate other genes expressed in an immunologically important organ, the thymus. 2. We used differential screening of a thymus cDNA library with cDNA probes made from thymus and from erythroblasts. 3. Approximately 50 clones which hybridized to the probe from thymus, but not from erythroblast, were isolated and sequenced from their termini. 4. Several clones were identified in data bank searches by their similarity to previously published sequences, and the partial sequences of these loci are reported here. 5. These include elongation factor 2, ribosomal protein S11, ribosomal protein S13, and the high mobility group protein. 6. Although these genes are not expected to be involved in an immune function, the availability of these sequences will facilitate the study of these loci in this species.