Base-specific reactions useful for DNA sequencing: methylene blue--sensitized photooxidation of guanine and osmium tetraoxide modification of thymine.

Exposure of DNA to methylene blue and visible or ultraviolet light causes guanine-specific modification, and subsequent treatment with piperidine leads to chain cleavage at each guanine residue. Treatment of DNA with osmium tetraoxide in dilute pyridine leads to thymidine-specific modification, and subsequent treatment with piperidine leads to chain cleavage at the modified thymidine residues. Both reactions can be used in conjunction with other base specific modifications described by Maxam and Gilbert (1) for the determination of the nucleotide sequence in DNA.

Structural proteins of polyoma virus: proteolytic degradation of virion proteins by exogenous and by virion-associated proteases.

A model has previously been proposed for the genetic relatedness of the structural proteins of polyoma virus, based upon similarities in the peptide maps of the major capsid protein VP1 with the virion proteins VP2 and VP3. Newer evidence suggests that this model is incorrect, and that protein VP1 is a product of one viral gene and that the multiple components of VP2 and VP3 are products of a second viral gene. Two-dimensional peptide maps of several preparations of polyoma purified separately from four separate infected-cell lysates has shown a variable content of VP1 peptides in proteins VP2 and VP3, with some preparations being free of detectable VP1 material in VP2 and VP3.

Relative quantitative assay of the biological activity of interferon messenger ribonucleic acid.

RNA extracted from cells previously stimulated to synthesize the antiviral protein, interferon, causes species-specific interferon synthesis when added to heterospecific cell cultures. Our results confirm the report of De Maeyer-Geugnard, De Maeyer & Montagnier (1972). We have used this observation to obtain a relative quantitative assay for the interferon messenger RNA activity.

Genetic economy of polyoma virus: capsid proteins are cleavage products of same viral gene.

Two-dimensional tryptic peptide maps of the nonhistone proteins of purified polyoma virus show marked similarities. Protein P(1) is a nondisaggregated, possibly covalent, dimer of the major capsid protein P(2), whereas P(3) and P(4) share several new peptides as well as many of the peptides derived from P(2). Extensive use of this kind of processing of viral proteins during the biosynthesis of DNA-containing animal viruses has not been reported previously.

Structural roles of polyoma virus proteins.

The superhelical, closed circular form of polyoma deoxyribonucleic acid (DNA) (Co 1) is bound in a 25S DNA-protein complex to the viral histone-like proteins after alkaline disruption of the virion. Nicked viral DNA or linear DNA are largely free of protein. Most of the viral protein disruption is in the form of capsomeres, sedimenting principally at 10S and 7S.

Gene therapy for human genetic disease?

In our view, gene therapy may ameliorate some human genetic diseases in the future. For this reason, we believe that research directed at the development of techniques for gene therapy should continue. For the foreseeable future, however, we oppose any further attempts at gene therapy in human patients because (i) our understanding of such basic processes as gene regulation and genetic recombination in human cells is inadequate; (ii) our understanding of the details of the relation between the molecular defect and the disease state is rudimentary for essentially all genetic diseases; and (iii) we have no information on the short-range and long-term side effects of gene therapy.

In vitro reassembly of shell-like particles from disrupted polyoma virus.

When purified polyoma virus is exposed to 0.01 M dithiothreitol in the presence of 0.2 M Na(2)CO(3)-NaHCO(3) (pH 10.