The vitamin A derivative retinoic acid (RA) is involved in vertebrate anteroposterior axis formation and cellular differentiation and has been shown to modulate the expression of a number of genes ...implicated in the control of early embryonal development. Under defined culture conditions, all-trans-RA induces differentiation of P19 embryonal carcinoma cells into neural derivatives. In this report, we describe the isolation and partial characterization of 14 RA-regulated genes from P19 cells committed to differentiate along the neural pathway. In addition to the previously recognized genes encoding vimentin, heat stable antigen, neural cadherin, Hox-B2, F52/MacMARCKS, thymosin beta 4b, and the murine homolog of COUP-TF1, we identified 7 novel genes, 5 of which are predominantly expressed in developing neural tissues as shown by in situ hybridization. The results confirm the usefulness of the P19 system in the isolation and study of the regulation of developmentally expressed genes.
A tagged medium-energy neutron beam has been used in a precise measurement of the absolute differential cross section for np back-scattering. The results resolve significant discrepancies within the ...np database concerning the angular dependence in this regime. The experiment has determined the absolute normalization with 1.5% uncertainty, suitable to verify constraints of supposedly comparable precision that arise from the rest of the database in partial wave analyses. The analysis procedures, especially those associated with evaluation of systematic errors in the experiment, are described in detail so that systematic uncertainties may be included in a reasonable way in subsequent partial wave analysis fits incorporating the present results.
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