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K Dunn

Publications and source records attributed to K Dunn.

95 records · Page 6Linked to original sources
PubMedDate not supplied

Cells expressing ENOD2 show differential spatial organization during the development of alfalfa root nodules.

We have used in situ hybridization to examine the spatial organization of cells expressing the early nodulin gene (ENOD2) during the development of alfalfa root nodules. ENOD2 gene expression was found in the nodule parenchyma, uninfected cells surrounding the symbiotic region of both effective and ineffective nodules. However, in empty nodules, ENOD2 gene expression was found in a mass of parenchyma cells at the base of the nodule. Similar results were also observed in 11-day-old nodules that contained infected cells but that had not yet begun to express leghemoglobin. Although early events of nodulation result in the induction of ENOD2 expression in cells at the nodule base, the pattern of cells expressing ENOD2 during nodule growth appears to be correlated with the development of other peripheral tissues.

Fabaceae↗
PubMedDate not supplied

Sequential expression of two late nodulin genes in the infected cells of alfalfa root nodules.

The Nms-22 and leghemoglobin (Lb) genes are expressed exclusively in the infected cells of alfalfa root nodules. Expression of these two late nodulin genes originated at distinct cellular boundaries within the symbiotic region of the nodule. The Nms-22 gene was expressed in all infected cells, including those just adjacent to the meristematic region. Lb gene expression was induced in older infected cells and was most prominent in the mature region of the nodule. Despite this temporal separation of gene expression, both the Nms-22 and Lb genes were expressed in nodules elicited by bacA mutants in which bacteroid development has been blocked just after release from the infection thread.

Fabaceae↗
PubMedDate not supplied

Characterization of a nodule-enhanced glutamine synthetase from alfalfa: nucleotide sequence, in situ localization, and transcript analysis.

We have characterized two glutamine synthetase (GS) cDNA clones (pGS13 and pGS100) representing mRNA from root nodules of alfalfa. pGS13 is a full-length version of a previously isolated partial cDNA from an alfalfa nodule cDNA library, while pGS100 was previously isolated from an alfalfa suspension culture cDNA library. Using the 3' untranslated region of the two cDNAs as gene-specific probes, we have shown that the GS genes represented by pGS100 and pGS13 are expressed in all organs tested, although at varying levels. pGS13, however, represents the nodule-enhanced GS gene class. Genomic Southern blot analysis using gene-specific probes shows multiple hybridizing bands, in each case suggesting multiple genes and/or alleles for each class of cytoplasmic GS genes. In situ hybridization of alfalfa nodule sections with gene-specific antisense RNA probes has shown that the nodule-enhanced GS genes are induced in the invasion zone and that their expression is limited to the symbiotic zone, while the GS genes represented by pGS100 are induced in the early symbiotic zone and are expressed throughout the symbiotic and senescent zones. Transcripts for both sets of GS genes are localized in the infected cells and based on the spatial expression pattern it would appear that the two gene classes are induced independently of the onset of nitrogen fixation.

Amino Acid Sequence↗
PubMedDate not supplied

Novice and expert head nurses: a comparative study of work activities and behaviours.

The head nurse represents a key management position in hospital organizations. This descriptive study examines the role of the head nurse and identifies differences that exist between newly appointed head nurses and experts in the position. Questionnaire, interview and nonparticipant observation methods were used to collect and analyze data. Recommendations for educational preparation, selection criteria and recruitment and retention strategies are made based upon the study results.

Clinical Competence↗