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At least 163 records · Page 9Linked to original sources
PubMed1962

Hyperchromicity and strand separation in bacterial DNA.

Studies of the per cent of strand separation of N(14)-N(15) hybrid coli DNA heated to various temperatures in formaldehyde have shown that the process of strand separation is a function of temperature and formaldehyde concentration and is directly related to the measured hyperchromicity. No strands separate until about 75 per cent of full hyperchromicity is obtained, and even at apparently full hyperchromicity a large fraction of the strands may be held together, possibly by guanine-cytosine-rich regions.

Cytosine↗
PubMedDate not supplied

Heterologous hybridization of bacterial DNA to the endoglucanases A and B structural genes celA and celB of Clostridium thermocellum.

DNA from various cellulolytic and non-cellulolytic bacteria was found to hybridize to Clostridium thermocellum NCIB10682 DNA fragments carrying the structural genes celA and celB which code for endoglucanases A and B. Homology to celA was detected in Agrobacterium rhizogenes, Azospirillum brasilense, Bacillus subtilis, Cellulomonas sp., Clostridium stercorarium, Erwinia chrysanthemi, Pseudomonas solanacearum and Streptomyces griseus. Homology to celB was detected only in B. subtilis, C. stercorarium and E. chrysanthemi. No homology to celA or celB was detected in Agrobacterium tumefaciens, Rhizobium japonicum, Rhizobium meliloti, Rhizobium ORS571 and Trichoderma reesei. Hybridization performed with the homologous strain NCIB10682 and with C. thermocellum LQRI suggested that the two strains were identical in terms of cel genes. In addition, it is likely that the C. thermocellum cel genes, whose number is presently estimated to be at least ten, do not belong to a gene family, since heterologous hybridization was observed only to a single small EcoRI or HindIII fragment homologous to celB.

Bacteria↗
PubMed2001

The role of the macrophage scavenger receptor in immune stimulation by bacterial DNA and synthetic oligonucleotides.

To assess the role of the macrophage scavenger receptor type A (SRA) in immune activation by CpG DNA, cytokine induction and DNA uptake were tested in vitro and in vivo using SRA knockout (SRA-/-) and wild type (WT) mice. As a source of CpG DNA, Escherichia coli DNA (EC DNA) and a 20-mer phosphorothioate oligodeoxynucleotide with two CpG motifs (CpG ODN) were used. In vitro, both EC DNA and the CpG ODN induced dose-dependent increases of interleukin (IL)-12 production by spleen cells and bone-marrow-derived macrophages (BMMPhi) from both SRA-/- and WT mice. The levels of cytokines produced by SRA-/- spleen cells and BMMPhi were similar to those of WT spleen cells and BMMPhi. When injected intravenously with CpG ODN and EC DNA, both SRA-/- and WT mice showed elevated serum levels of IL-12. To investigate further the role of the SRA, flow cytometry and confocal microscopy were performed to examine the uptake of fluorescently labelled oligonucleotides. SRA-/- and WT BMMPhi showed similarity in the extent of uptake and distribution of oligonucleotides as assessed by these two techniques. Together, these findings indicate that, while the SRA may bind DNA, this receptor is not essential for the uptake of CpG DNA or its immunostimulatory activity.

Animals↗
PubMed1992

Staphylococcus epidermidis bacteremia from transfusion of contaminated platelets: application of bacterial DNA analysis.

Septicemia is a rare complication of platelet transfusion. A case is reported of transfusion-associated septicemia in a 66-year-old man who received a 10-unit pool of platelets. During transfusion, he experienced rigors, wheezing, dyspnea, and fever. A total of four blood cultures drawn 10 and 36 hours after discontinuation of the transfusion grew Staphylococcus epidermidis. Culture of the residual platelet pool yielded S. epidermidis with a colony count of 10(5) organisms per mL. Strain identity of all four blood isolates and the platelet pool isolate was confirmed by gel electrophoresis of EcoRI and HindIII restriction digests of whole-cell DNA. There have been 31 prior reported cases of platelet transfusion-associated septicemia, of which 9 have been caused by coagulase-negative staphylococci. Systemic reactions to platelet transfusions should prompt consideration of transfusion-associated bacteremia as the cause.

Aged↗
PubMed2006

TLR9-independent activation of B lymphocytes by bacterial DNA.

The intracellular Toll-like receptor 9 (TLR9) is unique in its ability to recognize single-stranded DNA unmethylated at CpG motifs. Work from this laboratory showed that plasmid DNA is spontaneously internalized in B lymphocytes. This event is followed by the upregulation of costimulatory molecules and the acquisition of antigen presenting function by these cells. However, it is not known whether this phenomenon depends on TLR9. Because of the relevant role played by DNA-based drugs in immunotherapy and vaccination, and the central role of TLR9 signaling by CpG motifs, we decided to investigate whether signaling through TLR9 is a prerequisite for spontaneous transgenesis of lymphocytes. Here we found that transgene expression and upregulation of CD40 and CD86 costimulatory molecules was not inhibited by chloroquine treatment. Spontaneous transgenesis also occurred in B lymphocytes from TLR9-/- mice, and the injection of TLR9-/- transgenic B lymphocytes in C57Bl/6 mice induced both CD4 and CD8 T cell responses comparable to those induced by wild-type B lymphocytes. Collectively, these results suggest that plasmid DNA activates mammalian B lymphocytes through a TLR9 independent pathway.

Animals↗