Arrangement of base sequences in deoxyribonucleic Acid

Methods for the determination of deoxyribonucleic Acid homologies in streptomyces

Variations of the membrane filter technique for deoxyribonucleic acid (DNA) hybridizations were studied with respect to Streptomyces species. At the temperatures required for specific hybridization of DNA with the high melting temperature (T(m)) characteristic of Streptomyces, large amounts (up to 97%) of filter-bound DNA became eluted, in all reaction mixtures studied, within 21 hr. In most solutions this leaching was increased by the presence of sheared denatured DNA. Incubation of DNA-loaded filters in a solution of 50% formamide containing 6x standard saline citrate, at 48 C for 40 hr, was judged to be the best set of conditions tested based on relatively good retention of immobilized DNA, very low hybridization with unrelated DNA of a similarly high T(m) (from Sarcina lutea), and the formation of complexes similar in thermal stability to the native DNA. The expression of results as sheared DNA bound in relation to long-chain DNA retained is recommended when a high concentration of sheared DNA relative to immobilized DNA is used.

Simple genetic transformation assay for rapid diagnosis of Moraxella osloensis

A genetic transformation assay for unequivocal identification of strains of Moraxella osloensis is described. In this assay a stable tryptophan auxotroph is transformed to prototrophy by deoxyribonucleic acid (DNA) samples from other strains of M. osloensis but not by DNA samples from unrelated bacteria. The test is simple to perform and definitive results can be obtained in less than 24 h. The procedure, which is suitable for routine diagnosis in a clinical laboratory, involves a rapid method for preparation of crude transforming DNA from small quantities of bacterial cells and permits simultaneous examination of large numbers of isolated cultures. The assay was shown to correctly identify 27 strains previously classified as M. osloensis. Forty-five other gram-negative, oxidase-positive, nonmotile coccobacilli, which might be confused with M. osloensis unless subject to more extensive testing, were shown to be unrelated genetically to M. osloensis. The transformation assay clearly distinguishes M. osloensis from Acinetobacter. Although most strains of M. osloensis are nonfastidious, being able to grow in a mineral medium supplemented with a single organic carbon source, one of the strains tested was only able to grow on fairly complex media and could not be transformed to grow on simple media. Inability to alkalize Simmons citrate agar was shown not to be characteristic of all strains of M. osloensis.

Characterization and relatedness of marine vibrios pathogenic to fish: deoxyribonucleic acid homology and base composition

Deoxyribonucleic acid (DNA) isolated from several pathogenic marine vibrios was utilized in studies of base composition and nucleotide sequence relationships. Patterns of relatedness inferred from DNA criteria were found to correlate closely with those inferred from morphological, physiological, and serological analysis of the same organisms. The utility of the phenotypic and genotypic approaches to the determination of relatedness is discussed.

Deoxyribonucleic acid homology and relative genome size in Mycoplasma

The deoxyribonucleic acid homologies of Mycoplasma laidlawii type A and type B, M. pulmonis (#47 and #63), and M. hominis were determined by membrane methodology. The homology data revealed a difference in genome size between M. laidlawii type A and type B. This difference also held with stringent conditions of annealing (high temperature). Little or negligible homology was shown to exist between the M. laidlawii strains type A and type B and M. pulmonis strains 47 and 63 and M. hominis. M. hominis showed less than 10% homology to the M. pulmonis and M. laidlawii strains. Neither of the M. laidlawii strains showed more than 2% annealing to the M. pulmonis strains. Reaction rate studies are suggested as a means of demonstrating the phylogenetic relationship between the Mycoplasma and other microorganisms.

Base sequence homology and renaturation studies of the deoxyribonucleic acid of extremely halophilic bacteria

The genetic relatedness among various strains of halophilic bacteria has been assessed by deoxyribonucleic acid-deoxyribonucleic acid (DNA-DNA) duplex formation and ribosomal ribonucleic acid (RNA) hybridization. All of the strains of extremely halophilic rods are closely related, and the extent of divergence of base sequence is similar for the major and minor DNA components. Parallel experiments with ribosomal RNA revealed a relationship between the extremely halophilic rods and cocci and a more distant relationship to moderate halophiles and to a photosynthetic extreme halophile. Renaturation studies of halophile DNA exclude the possibility that the satellite DNA represents multiple copies of a small episomal element. The kinetics of DNA renaturation show that the genome size of the extreme and moderate halophiles is similar to that of Escherichia coli.

Polynucleotide sequence relationships among members of Enterobacteriaceae

Polynucleotide relationships were examined among many representatives of the Enterobacteriaceae by means of agar, membrane filter, and hydroxyapatite procedures. The amount of deoxyribonucleic acid (DNA) that reassociated was dependent, especially in interspecific reactions, on the annealing temperature. In only three cases: Escherichia coli-Shigella flexneri, Salmonella typhimurium-S. typhi, and Proteus mirabilis-P. vulgaris, was relative interspecific duplex formation 80% or higher. In most cases interspecies DNA duplex formation was 40% or less of that obtained from intraspecies DNA reassociation reactions. The stability of E. coli-S. flexneri DNA duplexes formed at either 60 or 75 C was virtually identical to that of homologous E. coli DNA duplexes, and the degree of interspecies duplex formation was minimally affected by the temperature increase (86% at 60 C; 77% at 75 C). The thermal stability of DNA duplexes formed at 60 C between DNA from E. coli and DNA from strains of Aerobacter aerogenes, S. typhimurium, S. typhi, and P. mirabilis was about 12 to 14 C below that of reassociated E. coli DNA. At 75 C, the formation of the interspecific DNA duplexes was markedly decreased, but the stability of the DNA able to reassociate at this temperature approximated that of reassociated E. coli DNA. The degree of reassociation and the thermal stability of E. coli-S. flexneri DNA duplexes suggests relatively little evolutionary divergence in these organisms. The other enterobacteria tested, however, have diverged to a point where less than one-half of their DNA can reanneal with E. coli DNA at 60 C and less than 10% reacts at 75 C. The degree of divergence between various enterobacteria does not appear to be uniform along the DNA molecule. Ribosomal ribonucleic acid (RNA)-specific sequences are conserved among most enterobacteria. An examination of messenger RNA relatively specific for the lactose operon suggests that specific chromosomal genes may diverge more or less than the genome as a whole.

Organ-specific estrogen-induced RNA synthesis resolved by DNA-RNA hybridization in the domestic fowl

In the domestic fowl and other oviparous vertebrates, estrogens induce hepatic synthesis of yolk proteins. The oviduct also increases in size and produces ovalbumin when estrogens are administered. DNA-RNA hybridization assays indicate that within 105 minutes following treatment with estrone the liver of immature pullets contains most, if not all, of the liver RNA species that are present in the livers of the laying hen. Because of limitations of the nucleic acid hybridization technique, which remain to be clearly defined, it is not known whether the hepatic RNA populations in estrone-treated pullets and laying hens are completely homologous or differ in some important way. The results indicate that the genomic response in the avian liver to exogenous estrone is "normal" (relative to the laying hen) and further suggest that the hepatic response to estrogen is primarily pertinent to vitellinogenesis.DNA-RNA hybridization assays on total RNA also indicate that estrogen-induced RNA species in the liver are not homologous to estrogen-evoked RNA species of the oviduct. Therefore, in these two target organs estrogen-evoked RNA synthesis appears to be in part organ-specific. These data indicate that the specificity of hormone action can be explained in part on the basis of induced synthesis of specific RNA molecules. Whether these alterations in transcription are due to indirect hormonal action or are the result of a primary action of estrogens or estrogen-binding site complexes on the genome and/or its repressors remains a basic question.

Homologies of deoxyribonucleic acids from Brucella ovis, canine abortion organisms, and other Brucella species

The bacterium that causes canine abortion has polynucleotide sequences similar, in deoxyribonucleic acid (DNA)-DNA homology studies, to those of Brucella suis and, by inference from previous data, those of B. abortus and B. melitensis as well as B. neotomae. Therefore, the organism causing canine abortion appears to be a member of the genus Brucella. DNA preparations from Serratia marcescens, Alcaligenes faecalis, and Bordetella bronchiseptica, 58, 62, and 66 mole% guanine plus cytosine, respectively, do not have detectable polynucleotide sequence homologies with B. suis DNA which is 56 mole% guanine plus cytosine. B. ovis DNA lacks some of the polynucleotide sequences present in B. suis DNA and appears to be a deletion mutant. However, a large proportion of B. ovis polynucleotides are similar to those of other Brucella species, which supports the inclusion of B. ovis in the genus.