Showing papers on "genomic DNA published in 1974"
TL;DR: The methodology presented provides a promising approach to the sequence analysis of large portions of the DNA of small viruses.
Abstract: Publisher Summary This chapter describes the methods useful for obtaining 22 P-labeled RNA transcription products that are derived from unique and limited regions of a DNA genome. Such RNA's reflect the sequence of the DNA from which they are transcribed and are suitable for hybridization procedures and for sequence analysis. Several approaches are presented. The first makes use of DNA restriction enzymes, such as those obtained from Hemophilus infiuenzae and H. aegyptius that are capable of cleaving DNA into small discrete products that can be purified by acrylamide gel electrophoresis. A second method makes use of DNA from deletionsubstitution mutants of viruses, to which transcribed RNA's may be annealed and from which RNA complementary to specific regions of the DNA, may be recovered and analyzed. The chapter describes procedures that have been developed in several laboratories. These techniques have been successfully employed to obtain RNA sequences for discrete regions of the DNA's of bacteriophage and SV40. The methodology presented provides a promising approach to the sequence analysis of large portions of the DNA of small viruses.
19 citations
Journal Article•
TL;DR: This discussion primarily concerns transcription level regulation, i.e., control over which sequences in the genomic DNA are transcribed, and indicates that this is the initial level of regulation in the differentiated animal cell.
Abstract: Gene regulation in animal cells may occur at several stages of RNA metabolism, including synthesis, processing, transport, and utilization of the RNA. This discussion primarily concerns transcription level regulation, i.e., control over which sequences in the genomic DNA are transcribed. Current evidence indicates that this is the initial level of regulation in the differentiated animal cell; this conclusion is supported by quantitative hybridization experiments as well as by other kinds of data. Recent experiments are considered which show that animal structural genes are in general DNA sequences occurring only once per haploid genome. For at least one system, the sea urchin embryo, the amount of nonrepetitive DNA sequence represented in the mRNA's is known. About 14,000 average-sized structural genes are represented in the polysomal mRNA of this 600-cell embryo. Studies on organization of DNA sequences show that at least 80% of the DNA of Xenopus and sea urchin consists of short (300 nucleotides) repetitive sequence elements interspersed with longer nonrepetitive sequence regions. This arrangement is an ordered one, suggesting selective value in evolution and therefore function. Such a sequence arrangement pattern could account for the system properties of gene regulation in animal cells.
16 citations
TL;DR: The DNA of L-929 cell nuclei was examined for the presence of an RNA fraction hybridized to the DNA that could possibly serve a role in gene regulation and a role for, as well as the nature of the attachment of this RNA to DNA is suggested.
Abstract: The DNA of L-929 cell nuclei was examined for the presence of an RNA fraction hybridized to the DNA that could possibly serve a role in gene regulation. A low molecular weight ([unk]4.5S) RNA fraction was observed as an RNA-DNA complex in chromatin preparations subfractionated on a Cs2SO4 density gradient. This RNA does not appear to be covalently attached to the DNA. Neither does it appear to be attached to the DNA via a protein component. The RNA is resistant to ribonuclease H but is slowly attached by ribonuclease A + Tl. A role for, as well as the nature of the attachment of this RNA to DNA is suggested.
2 citations