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Robert W Phillips

Publications and source records attributed to Robert W Phillips.

5 recordsLinked to original sources
PubMed2005

Differentiation of campylobacter populations as demonstrated by flagellin short variable region sequences.

The DNA sequence of the flaA short variable region (SVR) was used to analyze a random population of Campylobacter isolates to investigate the weakly clonal population structure of members of the genus. The SVR sequence from 197 strains of C. jejuni and C. coli isolated from humans, bovine, swine, and chickens identified a group of 43 strains containing disparate short variable region sequences compared to the rest of the population. This group contains both C. jejuni and C. coli strains but disproportionately consisted of bovine isolates. Relative synonymous codon usage analysis of the sequences identified two groups: one group typified C. jejuni, and the second group was characteristic for C. coli and the disparate alleles were not clustered. The data show that there is significant differentiation of Campylobacter populations according to the source of the isolate even without considering the disparate isolates. Even though there is significant differentiation of chicken and bovine isolates, the bovine isolates did not show any difference in ability to colonize chickens. It is possible that disparate sequences were obtained through the lateral transfer of DNA from Campylobacter species other than C. jejuni and C. coli. It is evident that recombination within the flaA SVR occurs rapidly. However, the rate of migration between populations appears to limit the distribution of sequences and results in a weakly clonal population structure.

Animals↗
PubMed2004

Multilocus sequence typing of Listeria monocytogenes by use of hypervariable genes reveals clonal and recombination histories of three lineages.

In an attempt to develop a method to discriminate among isolates of Listeria monocytogenes, the sequences of all of the annotated genes from the fully sequenced strain L. monocytogenes EGD-e (serotype 1/2a) were compared by BLASTn to a file of the unfinished genomic sequence of L. monocytogenes ATCC 19115 (serotype 4b). Approximately 7% of the matching genes demonstrated 90% or lower identity between the two strains, and the lowest observed identity was 80%. Nine genes (hisJ, cbiE, truB, ribC, comEA, purM, aroE, hisC, and addB) in the 80 to 90% identity group and two genes (gyrB and rnhB) with approximately 97% identity were selected for multilocus sequence analysis in two sets of L. monocytogenes isolates (a 15-strain diversity set and a set of 19 isolates from a single food-processing plant). Based on concatenated sequences, a total of 33 allotypes were differentiated among the 34 isolates tested. Population genetics analyses revealed three lineages of L. monocytogenes that differed in their history of apparent recombination. Lineage I appeared to be completely clonal, whereas representatives of the other lineages demonstrated evidence of horizontal gene transfer and recombination. Although most of the gene sequences for lineage II strains were distinct from those of lineage I, a few strains with the majority of genes characteristic of lineage II had some that were characteristic of lineage I. Genes from lineage III organisms were mostly similar to lineage I genes, with instances of genes appearing to be mosaics with lineage II genes. Even though lineage I and lineage II generally demonstrated very distinct sequences, the sequences for the 11 selected genes demonstrated little discriminatory power within each lineage. In the L. monocytogenes isolate set obtained from one food-processing plant, lineage I and lineage II were found to be almost equally prevalent. While it appears that different lineages of L. monocytogenes can share habitats, they appear to differ in their histories of horizontal gene transfer.

Animals↗
PubMed2002

Kineococcus radiotolerans sp. nov., a radiation-resistant, gram-positive bacterium.

A gram-type positive, motile, coccus-shaped organism was isolated from a radioactive work area. Strain SRS30216T is an orange-pigmented bacterium that is catalase-positive, oxidase-negative and urease-negative. The orange pigment is most likely a carotenoid with absorption peaks at approximately 444, 471 and 501 nm. Cells normally grew in clusters, but individual, motile, flagellated cells were also observed. Growth of strain SRS30216T occurred at temperatures between 11 and 41 degrees C, between pH 5 and 9 and at NaCl concentrations up to and including 5%. Fatty acid composition was limited, with >90% of the fatty acids being anteiso 15:0. Alkenes of 19-24 carbons in length were detected during examination of the neutral lipids. Strain SRS30216T demonstrated high levels of resistance to gamma-radiation and desiccation. The most closely related recognized species is Kineococcus aurantiacus RA 333T, which is 93% similar in 16S rDNA sequence. DNA-DNA hybridization revealed only 31% similarity between these two organisms. It is proposed that SRS30216T (= ATCC BAA-149T = DSM 14245T) represents the type strain of a novel species in the genus Kineococcus, Kineococcus radiotolerans sp. nov..

Actinomycetales↗
PubMed2002

Gravity: It's the law.

Based on experience in microgravity and on centrifuge induced hypergravity, exposure to either altered force field causes marked effects in animals and humans. It would seem logical that changes from unit gravity would have different effects depending on whether gravity is increased or decreased. Examples will be presented of responses to altered gravitational fields and changes in human and animal musculoskeletal, cardiopulmonary neurovestibular and metabolic responses.

Journal Article↗