1. Ribonucleic acid (RNA) was isolated from calf spleen tissue by the new Kirby procedure followed by three phenol washings to reduce the peptide-protein contamination. Ultraviolet absorption spectra and colorimetric analyses indicated the reduction or absence of protein, peptide, DNA and, after methoxyethanol purification, polysaccharide from the isolated RNA.

  2. Ultracentrifuge sedimentation analysis showed three components in the undegraded RNA isolate: a 27S fraction, an 18S fraction and a 7-8S fraction. This ribosomal-messenger RNA was added to non-nutrient medium for induction testing.

  3. Neither embryos nor competent gastrula ectoderm of Xenopus laevis demonstrated, in a limited series, any tissue-specific inductive response, but both experimental systems in the RNA-conditioned medium did demonstrate enhanced epithelial development as compared with the control systems.

  4. Postgastrula stages of Taricha torosa and Ambystoma gracile exposed during development to reagent-grade beef liver s-RNA demonstrated hyperplasia in the dorsal mesencephalon-rhombencephalon and the anterior neural crest mesenchyme population along with an enhancement of auditory and posterior entodermal epithelial development.

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