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By the use of the gene template it will be shown that D appears at two different sites on the Rh locus, and that the locus cannot simply be DCE - or a similar one. Further, -D- does not appear to be a super Rh(0) as described by Wiener. Finally, a simple explanation is offered for the action of incomplete (blocking) and agglutinating antibodies.
In this paper we consider a model for the selection and evolution of biological macromolecules when their reproduction is based on complementary instruction. The model is an extension of one of Eigen's models for selection and takes in account explicitly the formation of both single stranded and double stranded molecular complexes. We construct exact solutions to the rate equations for the case of constant rate parameters and error distributions. Criteria for selection are discussed.
An experimental system is described, which opens up a novel pathway towards a molecular understanding of the origin of life. The systemic conditions for the evolution of biological macromolecules are investigated in detail.
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We have isolated a conditional lethal mutant of bacteriophage 12 which makes plaques only on E. coli strains carrying a UGA suppressor. It grows normally in nonsuppressing hosts but does not lyse such strains. The mutation complements with amber mutations in each of the three known phage cistrons. These observations lead us to postulate the existence of a fourth gene in the RNA phage.
The Rpo-mediated recombination of phage lambda takes place independently of the recA function and is promoted by DNA-dependent RNA polymerase of Escherichia coli [Ikeda, H. & Kobayashi, I. (1977) Proc. Natl. Acad Sci. USA 74, 3932--3936]. The crossovers were particularly frequent to the cIII-N and N-cII regions which are transcribed actively. To determine whether the transcription process required for the recombination is the initiation step or the chain elongation step, we have examined the effect of bacterial rho mutation, which affects transcription termination, on the distribution of crossover points in the lambda phage genome. The crossovers in the cII-S interval took place more frequently in rho mutant strains than in wild-type strains. Analysis of lambda mRNA showed that much more O-P-Q mRNA is synthesized in the rho mutant cells than in the wild-type cells and is largely produced by the readthrough from the PR promotor. These results strongly suggest that the chain elongation in transcription plays an essential role in this recombination. Physical analysis of the recombinant phage DNA showed that this recombination is a legitimate type. Models are presented to explain how the transcription complex can promote this recA-independent recombination.
This paper points out certain theoretical problems in DNA synthesis associated with antiprimer transcription and with circularization that could oblige RNA tumor viruses to rely on a polyploid genome. It is suggested that each completed act of reverse transcription may be coupled with an act of genetic recombination aimed at recovering the antiprimer information from an adjacent genome subunit in a polyploid train. A partially double-stranded DNA transcript could then be formed with sufficient terminal redundancy to permit circularization. The model provides satisfactory explanations for observed genetic interactions (particularly recombination and heterozygote formation), for inactivation data and for selective subunit transcription.
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Rabbit globin mRNA has been purified and used as a template by reverse transcriptase. The resulting duplex molecule consisting of rabbit globin mRNA/cNDA has been linked in vitro to Eco RI cleaved plasmid Col E1 DNA. Transformation of E. coli C6OO by this recombinant molecule has been achieved. Transformed bacteria acquire the colicin EQ immunity of Col E1 and a closed circular DNA species of 4.40-4.45 x 10 (6) daltons in molecular weight, an increase of 2.0-2.5 x 10(5) daltons compared to that of the parent plasmid DNA. In addition , 3H cDNA synthesized from globin RNA hybridized perferentially to the recombinant plasmid DNA.
An in vitro protein-synthesizing system can synthesize two ribonucleic acid (RNA) polymerase subunits of Escherichia coli, beta and beta', when a transducing phage deoxyribonucleic acid (DNA) template containing the rpoB region of the bacterial chromosome is added. Recombinant rpoB transducing phages were isolated that carry "nonsense" mutations of the class rpo-rifampin zero amber (formally referred to as rifoam). DNA was extracted from two of these phages. These DNAs are unable to direct the synthesis of beta subunits, whereas beta' synthesis is unaffected. Both mutations can be efficiently suppressed in vitro by the addition of suppressor transfer RNA. One of the mutations (rpoB115) produces a detectable nonsense (or restart) fragment of the beta protein in the absence of suppression. It is concluded that rpoB115 is an amber mutation within the structural gene for the beta subunit of RNA polymerase.
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Explore the source record for details and available documents.
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Explore the source record for details and available documents.
Explore the source record for details and available documents.