PubMed Health⌕ Search

Biomedical subjects

R L Sinsheimer

Publications and source records attributed to R L Sinsheimer.

13 recordsLinked to original sources
PubMed1977

Separation of the complementary strands of DNA fragments on polyacrylamide gels.

32P-labeled (in vivo) phiX174 RFI DNA was restricted by Hinc II. Three aliquots of the same digest: a) nondenatured, b) heat denatured, and c) denatured by 5 mM Me-HgOH were analyzed on 3-15% acrylamide gel gradients or on 3% gels with reduced N,N'-methylene-bis-acrylamide. The autoradiography of the gels showed that the nondenatured sample migrates two times faster than the denatured samples. After denaturation each original fragment appeared as a doublet. Using in vitro synthesized RFI DNA labeled only in negative strand with 32P we could identify the position of the negative strand in each denatured doublet. The single strand DNA fragments could be recovered from the gel slices on a semi-preparative scale by electrophoresis into dialysis tubing.

Coliphages↗
PubMed1977

Recombinant DNA.

Explore the source record for details and available documents.

Base Sequence↗
PubMed1976

Process of infection with bacteriophage phi X174 XLI. Synthesis of defective phi X particles at 15 degrees C.

At 15 degrees C, phi X174-infected cells make single-stranded viral DNA fragments, varying in size from 0.2 to 0.9 times that of phi X DNA. In non-deproteinized lysates, this single-stranded DNA is found associated with proteins in particles sedimenting heterogeneously with an S20, w average of 80 to 90S. These particles do not differ appreciably from mature virus in polypeptide composition. Chase experiments, at 37 degrees C, of the label incorporated into this DNA at 15 degrees C suggest that both the single-stranded DNA fragments and the 80 to 90S particles are not precursors of virions but are defective end products.

Coliphages↗
PubMed1975

New method for isolation and sequence determination of 5'-terminal regions of bacteriophage phiX174 in vitro mRNAs.

We have determined the nucleotide sequences of the 5'-terminal oligonucleotides, produced by RNase T1 digestion of bacteriophage phiX174 mRNAs synthesized in vitro. The major sequences are: pppCpGp(Ap), pppApUpCpGp(Cp), pppAp(Ap)2UpCp(Up)2Gp(Gp), and pppAp(Ap)3UpCp(Up)2Gp(Gp). The sequences of several minor 5'-terminal oligonucleotides were also determined. For this research we have devised a simple isolation procedure, for the 5'-terminal oligonucleotides, based upon hydroxylapatite chromatography and two-dimensional thin-layer separation. This method allows for the rapid and quantitative recovery of all oligonucleotides containing 5'-triphosphate end groups and should be generally useful for sequence on 5' termini of mRNAs.

Base Sequence↗
PubMed1975

Recombinant DNA molecules of bacteriophage phi chi174.

Phi chi174 DNA structures containing two different parental genomes were detected genetically and examined by electron microscopy. These structures consisted of two monomeric double-stranded DNA molecules linked in a figure 8 configuration. Such DNA structures were observed to be formed preferentially in host recA+ cells or recA+ cell-free systems. Since the host recA+ allele is required for most phi chi174 recombinant formation, we conclude that the observed figure 8 molecules are intermediates in, or end products of, 1 phi chi174 recombination event. We propose that recombinant figure 8 DNA molecules arise as a result of "single-strand aggression," are stabilized by double-strand "branch migration," and represent a specific example of a common intermediate in genetic recombination.

Cell-Free System↗
PubMed1975

Process of infection with bacteriophage phiX174. XXXVII. RNA metabolism in phiX174-infected cells.

The RNA produced in vivo from bacteriophage phiX174 DNA has been analyzed by polyacrylamide-agarose gel electrophoresis and sedimentation in dimethyl sulfoxide gradients, and the results of Hayashi and Hayashi (1970) have been confirmed and extended. An efficient procedure for recovery of RNA from gels, followed by a hybridization assay, has indicated the presence in infected cells of 18 distinct RNA species with sizes up to and greater than the unit (viral) length. The sizes of phiX mRNA's were similar irrespective of whether material was analyzed on gels or in dimethyl sulfoxide gradients. When virus-induced RNA was detected by a double-label method, seven additional low-molecular weight species were observed on gels and the resolution of dimethyl sulfoxide gradients was enhanced. The present results lend support to aspects of the model of Hayashi and Hayashi (1970) for the generation of these discrete mRNA species; an alternative model is also discussed.

Coliphages↗