Biomedical subjects

Christine Anderson

Publications and source records attributed to Christine Anderson.

4 recordsLinked to original sources

PubMed2006

Sequencing of the intergenic 16S-23S rRNA spacer (ITS) region of Mollicutes species and their identification using microarray-based assay and DNA sequencing.

We have completed sequencing the 16S-23S rRNA intergenic transcribed spacer (ITS) region of most known Mycoplasma , Acholeplasma , Ureaplasma , Mesoplasma , and Spiroplasma species. Analysis of the sequence data revealed a significant interspecies variability and low intraspecies polymorphism of the ITS region among Mollicutes . This finding enabled the application of a combined polymerase chain reaction-microarray technology for identifying Mollicutes species. The microarray included individual species-specific oligonucleotide probes for characterizing human Mollicutes species and other species known to be common cell line contaminants. Evaluation of the microarray was conducted using multiple, previously characterized, Mollicutes species. The microarray analysis of the samples used demonstrated a highly specific assay, which is capable of rapid and accurate discrimination among Mollicutes species.

Animals↗

PubMed2006

Discovery of natural atypical nonhemolytic Listeria seeligeri isolates.

We found seven Listeria isolates, initially identified as isolates with the Xyl(+) Rha(-) biotype of Listeria welshimeri by phenotypic tests, which exhibited discrepant genotypic properties in a well-validated Listeria species identification oligonucleotide microarray. The microarray gives results of these seven isolates being atypical hly-negative L. seeligeri isolates, not L. welshimeri isolates. The aberrant L. seeligeri isolates were d-xylose fermentation positive, l-rhamnose fermentation negative (Xyl(+) Rha(-)), and nonhemolytic on blood agar and in the CAMP test with both Staphylococcus aureus (S(-) reaction) and Rhodococcus equi (R(-) reaction). All genes of the prfA cluster of L. seeligeri, located in the prs-ldh region, including the orfA2, orfD, prfA, orfE, plcA, hly, orfK, mpl, actA, dplcB, plcB, orfH, orfX, orfI, orfP, orfB, and orfA genes, were checked by PCR and direct sequencing for evidence of their presence in the atypical isolates. The prs-prfA cluster-ldh region of the L. seeligeri isolates was approximately threefold shorter due to the loss of orfD, prfA, orfE, plcA, hly, orfK, mpl, actA, dplcB, plcB, orfH, orfX, and orfI. The genetic map order of the cluster genes of all the atypical L. seeligeri isolates was prs-orfA2-orfP-orfB-orfA-ldh, which was comparable to the similar region in L. welshimeri, with the exception of the presence of orfA2. DNA sequencing and phylogenetic analysis of 17 housekeeping genes indicated an L. seeligeri genomic background in all seven of the atypical hly-negative L. seeligeri isolates. Thus, the novel biotype of Xyl(+) Rha(-) Hly(-) L. seeligeri strains can only be distinguished from Xyl(+) Rha(-) L. welshimeri strains genotypically, not phenotypically. In contrast, the Rha(+) Xyl(+) biotype of L. welshimeri would not present an identification issue.

Animals↗

PubMed2004

bryA: an unusual modular polyketide synthase gene from the uncultivated bacterial symbiont of the marine bryozoan Bugula neritina.

"Candidatus Endobugula sertula," the uncultivated bacterial symbiont of Bugula neritina, is the proposed source of the bryostatin family of anticancer compounds. We cloned a large modular polyketide synthase (PKS) gene complex from "Candidatus Endobugula sertula" and characterized one gene, bryA, which we propose is responsible for the initial steps of bryostatin biosynthesis. Typical PKS domains are present. However, acyltransferase domains are lacking in bryA, and beta-ketoacyl synthase domains of bryA cluster with those of PKSs with discrete, rather than integral, acyltransferases. We propose a model for biosynthesis of the bryostatin D-lactate starter unit by the bryA loading module, utilizing atypical domains homologous to FkbH, KR, and DH. The bryA gene product is proposed to synthesize a portion of the pharmacologically active part of bryostatin and may be useful in semisynthesis of clinically useful bryostatin analogs.

Amino Acid Sequence↗

PubMed2002

QS-21 structure/function studies: effect of acylation on adjuvant activity.

QS-21 is a natural saponin adjuvant derived from the tree Quillaja saponaria Molina. Previous studies over a limited dose range suggested the acylation is critical to adjuvant activity. In this study, we prepared DS-1 (deacylated QS-21) and RDS-1 (reacylated DS-1 with dodecylamine at a different site than QS-21) to determine the effect on a dose-response curve over a wider range in mice. DS-1 and RDS-1 induced IgG1 responses at higher doses compared to that induced by QS-21. DS-1 was inactive for inducing IgG2a or CTL responses at any doses. RDS-1 showed moderate IgG2a response at 240 microg, but did not show CTL response at any dose evaluated.

Acylation↗