Antibodies specific for 7-methylguanosine (m7G) were evaluated for their ability to inhibit the translation of chorion mRNA in a wheat germ, cell-free amino acid incorporating system. Results obtained with antibody concentrations of 0.5--1.5 microM revealed dose-dependent inhibition of [3H]-labeled amino acid incorporation into acid-insoluble radioactivity. Inhibition of translation was attributed to the interaction of anti-m7G antibodies with the 5' termini of chorion mRNAs on the basis that (a) anti-m7G antibodies coupled to Sepharose (anti-m7G-Sepharose) immunospecifically retained 5'-terminal cap structures of chorion mRNAs, i.e., m7G (5')ppp(5')Nm, (b) significant inhibition of translation required a 2-h preincubation of anti-m7G antibodies with mRNA, and (c) similar preincubation periods with anti-m7G antibodies in the presence of the competing nucleoside hapten (m7G) obviated the inhibitory effect of the antibody. The nature of the anti-m7G antibody-mRNA complex was examined by digesting chorion mRNA with nuclease P1 before (predigested) and after (postdigested) immunospecific adsorption to anti-m7G-Sepharose adsorbent. Whereas predigested preparations yielded a single cap structure of the type m7G(5')ppp(5')N, the predominating cap in the postdigested sample was m7G(5')ppp(5')NpNpN. These latter data revealed that the nucleotide sequence adjacent to the cap was not significantly masked by the antibody and suggest the utility of anti-m7G antibody as a site-specific probe.
Public investment in health research is concentrated disproportionately in a limited number of United States medical schools: about 75 per cent of federal health-research expenditures occur in the "Top 40" institutions. The heavy resource demands of advanced research, coupled with constrained public investment in the foreseeable future, will cause a gradual shift of resources toward the already research-rich schools. The various implications of this shift in resources for different categories of medical schools are described under different assumptions for the future: growth, a steady state, and decline. These developments underscore a public-policy dilemma. The further concentration of health-research resources in centers of excellence, which is justifiable in terms of maximizing the potential scientific return on the public's investment, is apt to prove disruptive to medical education in many schools in the middle and lower strata of funded research activity.
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