About: Ribosomal DNA is a(n) research topic. Over the lifetime, 7266 publication(s) have been published within this topic receiving 407281 citation(s).
Papers published on a yearly basis
TL;DR: Analysis of the genomic DNA from a bacterial biofilm grown under aerobic conditions suggests that sulfate-reducing bacteria, despite their anaerobicity, were present in this environment.
Abstract: We describe a new molecular approach to analyzing the genetic diversity of complex microbial populations. This technique is based on the separation of polymerase chain reaction-amplified fragments of genes coding for 16S rRNA, all the same length, by denaturing gradient gel electrophoresis (DGGE). DGGE analysis of different microbial communities demonstrated the presence of up to 10 distinguishable bands in the separation pattern, which were most likely derived from as many different species constituting these populations, and thereby generated a DGGE profile of the populations. We showed that it is possible to identify constituents which represent only 1% of the total population. With an oligonucleotide probe specific for the V3 region of 16S rRNA of sulfate-reducing bacteria, particular DNA fragments from some of the microbial populations could be identified by hybridization analysis. Analysis of the genomic DNA from a bacterial biofilm grown under aerobic conditions suggests that sulfate-reducing bacteria, despite their anaerobicity, were present in this environment. The results we obtained demonstrate that this technique will contribute to our understanding of the genetic diversity of uncharacterized microbial populations.
Abstract: A set of oligonucleotide primers capable of initiating enzymatic amplification (polymerase chain reaction) on a phylogenetically and taxonomically wide range of bacteria is described along with methods for their use and examples. One pair of primers is capable of amplifying nearly full-length 16S ribosomal DNA (rDNA) from many bacterial genera; the additional primers are useful for various exceptional sequences. Methods for purification of amplified material, direct sequencing, cloning, sequencing, and transcription are outlined. An obligate intracellular parasite of bovine erythrocytes, Anaplasma marginale, is used as an example; its 16S rDNA was amplified, cloned, sequenced, and phylogenetically placed. Anaplasmas are related to the genera Rickettsia and Ehrlichia. In addition, 16S rDNAs from several species were readily amplified from material found in lyophilized ampoules from the American Type Culture Collection. By use of this method, the phylogenetic study of extremely fastidious or highly pathogenic bacterial species can be carried out without the need to culture them. In theory, any gene segment for which polymerase chain reaction primer design is possible can be derived from a readily obtainable lyophilized bacterial culture.
TL;DR: It is concluded that the rDNA sl variants and/or associated loci are under selection in CCII, which demonstrates that Rrn1 and Rrn2 are useful as new genetic markers.
Abstract: Spacer-length (sl) variation in ribosomal RNA gene clusters (rDNA) was surveyed in 502 individual barley plants, including samples from 50 accessions of cultivated barley, 25 accessions of its wild ancestor, and five generations of composite cross II (CCII), an experimental population of barley. In total, 17 rDNA sl phenotypes, made up of 15 different rDNA sl variants, were observed. The 15 rDNA sl variants comprise a complete ladder in which each variant differs in length from adjacent variants by approximately equal to 115 nucleotide pairs. Studies of four rDNA sl variants in an F2 population showed that these variants are located at two unlinked loci, Rrn1 and Rrn2, each with two codominant alleles. Using wheat-barley addition lines, we determined that Rrn1 and Rrn2 are located on chromosomes 6 and 7, respectively. The nonrandom distribution of sl variants between loci suggests that genetic exchange occurs much less frequently between than within the two loci, which demonstrates that Rrn1 and Rrn2 are useful as new genetic markers. Frequencies of rDNA sl phenotypes and variants were monitored over 54 generations in CCII. A phenotype that was originally infrequent in CCII ultimately became predominant, whereas the originally most frequent phenotype decreased drastically in frequency, and all other phenotypes originally present disappeared from the population. We conclude that the sl variants and/or associated loci are under selection in CCII.
01 Jan 1989
Abstract: With a standard set of primers directed toward conserved regions, we have used the polymerase chain reaction to amplify homologous segments ofmtDNA from more than 100 animal species, including mammals, birds, amphib- ians, fishes, and some invertebrates. Amplification and direct sequencing were possible using unpurified mtDNA from nano- gram samples of fresh specimens and microgram amounts of tissues preserved for months in alcohol or decades in the dry state. The bird and fish sequences evolve with the same strong bias toward transitions that holds for mammals. However, because the light strand of birds is deficient in thymine, thymine to cytosine transitions are less common than in other taxa. Amino acid replacement in a segment of the cytochrome b gene is faster in mammals and birds than in fishes and the pattern of replacements fits the structural hypothesis for cytochrome b. The unexpectedly wide taxonomic utility ofthese primers offers opportunities for phylogenetic and population research.
TL;DR: Oligodeoxynucleotides that are complementary to conserved regions at the 5' and 3' termini of eukaryotic 16S-like rRNAs were used to prime DNA synthesis in repetitive cycles of denaturation, reannealing, and DNA synthesis.
Abstract: Polymerase chain reaction conditions were established for the in vitro amplification of eukaryotic small subunit ribosomal (16S-like) rRNA genes. Coding regions from algae, fungi, and protozoa were amplified from nanogram quantities of genomic DNA or recombinant plasmids containing rDNA genes. Oligodeoxynucleotides that are complementary to conserved regions at the 5' and 3' termini of eukaryotic 16S-like rRNAs were used to prime DNA synthesis in repetitive cycles of denaturation, reannealing, and DNA synthesis. The fidelity of synthesis for the amplification products was evaluated by comparisons with sequences of previously reported rRNA genes or with primer extension analyses of rRNAs. Fewer than one error per 2000 positions were observed in the amplified rRNA coding region sequences. The primary structure of the 16S-like rRNA from the marine diatom, Skeletonema costatum, was inferred from the sequence of its in vitro amplified coding region.