Biomedical subjects

Claudia Goyer

Publications and source records attributed to Claudia Goyer.

4 recordsLinked to original sources

PubMed2006

Identification of low-temperature-regulated genes in the fire blight pathogen Erwinia amylovora.

Genes involved in pathogenicity of several plant pathogens were shown to be induced at relatively cold temperatures. Loci from the fire blight pathogen Erwinia amylovora (Burrill) induced at 18 degrees C were identified using the miniTn5 transposon that contains the promoterless reporter gene gusA coding for beta-glucuronidase (GUS). Certain mutants (2.7%) expressed GUS predominantly at 18 degrees C on minimal medium plates, indicating that the transposon had been inserted downstream of a putatively thermoregulated promoter. Those mutants were further screened with a quantitative GUS fluorometric assay. A total of 21 mutants were selected: 19 mutants had a transposon insertion in temperature-dependent genetic loci, with a 2.2- to 6.3-fold induction of gusA gene expression at 18 degrees C, and two mutants with impaired growth at 18 degrees C. Some of these genetic loci encoded (i) proteins implicated in flagella biosynthesis, biotin biosynthesis, multi-drug efflux, and type II secretion protein, and (ii) proteins of unknown function.

Bacterial Proteins↗

PubMed2005

Potato expressed sequence tag generation and analysis using standard and unique cDNA libraries.

To help develop an understanding of the genes that govern the developmental characteristics of the potato (Solanum tuberosum), as well as the genes associated with responses to specified pathogens and storage conditions, The Canadian Potato Genome Project (CPGP) carried out 5' end sequencing of regular, normalized and full-length cDNA libraries of the Shepody potato cultivar, generating over 66,600 expressed sequence tags (ESTs). Libraries sequenced represented tuber developmental stages, pathogen-challenged tubers, as well as leaf, floral developmental stages, suspension cultured cells and roots. All libraries analysed to date have contributed unique sequences, with the normalized libraries high on the list. In addition, a low molecular weight library has enhanced the 3' ends of our sequence assemblies. Using the combined assembly dataset, unique tuber developmental, cold storage and pathogen-challenged sequences have been identified. A comparison of the ESTs specific to the pathogen-challenged tuber and foliar libraries revealed minimal overlap between these libraries. Mixed assemblies using over 189,000 potato EST sequences from CPGP and The Institute for Genomics Research (TIGR) has revealed common sequences, as well as CPGP- and TIGR-unique sequences.

DNA, Complementary↗

PubMed2004

Streptomycete spores entrapped in chitosan beads as a novel biocontrol tool against common scab of potato.

Spores of Streptomyces melanosporofaciens EF-76, an actinomycete that inhibits the growth of several plant pathogens, were incorporated in beads of chitosan and polyphosphate using the entrapment technique called complex coacervation. The degradation of spore-loaded beads was monitored by measuring the residual amount of chitosan in soil and by enumerating the S. melanosporofaciens population over time. After the introduction of spore-loaded chitosan beads into soil, the amount of chitosan in sterile soil remained at 1.550 mg/g throughout the first week and diminished to 0.101 mg/g after 7 weeks. Bead degradation proceeded faster in non-sterile soil but a progressive release of both chitosan oligomers and the antagonistic microbial agent was nevertheless observed. Application of these spore-loaded chitosan beads to seed potato tubers protected progeny tubers against common scab.

Biodegradation, Environmental↗

PubMed2002

Effect of amino acids on thaxtomin A biosynthesis by Streptomyces scabies.

The regulatory effect of amino acids on the production of thaxtomin A, a phytotoxin produced by Streptomyces scabies, was investigated. Tryptophan had an important inhibitory effect on the toxin biosynthesis in all five strains of S. scabies tested. Two other aromatic amino acids (tyrosine and phenylalanine) also inhibited thaxtomin A biosynthesis, while aliphatic amino acids did not cause an important decline in thaxtomin A production. Methylation of tryptophan prevented or reduced the inhibitory effect on thaxtomin A biosynthesis. In spite of the inhibitory action of tryptophan and phenylalanine on thaxtomin A production, incorporation of these radiolabeled molecules into thaxtomin A confirmed that they are metabolic precursors for the biosynthesis of the phytotoxin.

Bacterial Toxins↗