Adjuvant action of poly A:U on T and B rosette-forming cells in SRBC-immunized mice. Analysis by two rosette assay methods

The adjuvant action of complexes of polyadenylic and polyuridylic acids (poly A:U) on the primary immune response to SRBC was studied with respect to its effect on the production of thymus-derived (T) and bone marrow-derived (B) rosette-forming cells (RFC). RFC were assayed by two separate methods; one in which rosettes were prepared by incubation at 37 °C and then at 4 °C, the other by centrifugation at 4 °C. Two to three times more RFC were detected in mice receiving SRBC only when RFC were assayed by the incubation method. Most RFC detected by the incubation method were <i>Θ</i>-negative (BRFC) whereas 15–32% of the RFC detected by the centrifugation method were <i>Θ</i> -positive (TRFC). Both methods detected a 2- to 3-fold amplification of BRFC in mice receiving SRBC plus poly A:U. However, while the centrifugation method detected a 2- to 3-fold increase in T RFC, the incubation method detected a greater than 10-fold amplification of T RFC.

In vitro synthesis of DNA complementary to purified rabbit globin mRNA (RNA-dependent DNA polymerase-reticulocyte-hemoglobin-density gradient centrifugation-oligo(dT) primer)

Several properties of the viral RNA-dependent DNA polymerases and of rabbit globin mRNA make it possible to consider synthesis of the globin gene in vitro. These enzymes copy an RNA template using a short sequence of complementary nucleotides as a primer. Furthermore, globin mRNA has a 3'-terminal sequence of adenylic acid residues that make it particularly suitable as a template, since oligo(dT) can be annealed to a specific site on the mRNA. This small primer could phase the DNA polymerase, possibly ensuring that replication is initiated from that end of the globin message. We have used this approach and find that purified mRNA is an efficient template for the polymerase enzyme. The reaction requires the RNA template and the four deoxyribonucleoside triphosphates, and it is markedly stimulated by the addition of oligo(dT). Consistent with the expectation that the oligo(dT) uniquely phases the polymerase at an adenine-rich region in the globin message, oligo(dG), oligo(dC), and oligo(dA) fail to serve as primers. The product has a density intermediate between that of DNA and RNA, and shifts to a lighter DNA density after treatment with base. Further, it is specifically complementary to globin mRNA and sediments slightly faster in an alkaline sucrose gradient than a DNA standard that has a molecular weight of 129,000. The data suggest that a major portion of the DNA product is a sequence of at least 500 bases, about 50 more than would be necessary to encode rabbit globin. The potential usefulness of this interesting product is discussed.

Selective condensation of aminoacyl adenylates by nucleoproteinoid microparticles (prebiotic-lysine-model system-genetic code)

Microparticles composed of each of four enzymically synthesized homopolynucleotides and the same lysine-rich proteinoid have been found to influence the condensation of the AMP-anhydrides of each of four amino acids. The conditions of preparation of the particles and other variables of the experiments control the types of reaction. When a specified set of conditions was identified empirically, the incorporation favored the amino acids whose present-day codons are related to the homopolynucleotide in the particle.