1S801 is a transposable element isolated from Pseudomonas syringae pathovar (pv.) phaseolicola, the causal agent of halo blight of bean. Fragments of the element are present in multiple copies on an indigenous plasmid, pMMC7105, of strain LR781, and have been implicated as sites of homologous recombination leading to imprecise excision of the chromosomally integrated form of the plasmid. The element, which has been completely sequenced, is 1512 base pairs in length and is unusual among transposable elements in that it does not have direct or inverted repeats in its termini. The terminal regions of the element were uncoupled from the two major open reading frames, and trans-acting activity of the putative transposase was demonstrated in Escherichia coli (recA). An alignment of the sequences of thirteen insertions defined the precise borders of the element, and demonstrated that it does not duplicate its targets upon insertion. The target specificity of IS801 is similar to, but more degenerate than, the target specificity of two transposable elements to which it is closely related, IS91 and IS1294. The consensus derived from the aligned target sequences is G/C-A/G-A-C/G, and the target tetramer is found immediately adjacent to the right terminus of the element upon transposition. IS91 was demonstrated to mobilize 1S801, but not with the specificity characteristic of 1S801. The structure of 1S801 and the characteristics of IS91-activated transposition of 1S801 are discussed in light of a proposed model for IS91 transposition, and it is suggested that 1S801 could have been derived from IS91 by a modification of its left end. Remnants of IS801 are present near avirulence genes of various P. syringae pathovars, suggesting that the element has been involved in genetic rearrangements in the vicinity of these loci. / Graduation date: 1996

Thesis (Ph. D.) -- California Institute of Technology, 2010. / Title from home page (03/01/2010). Advisor and committee chair names found in the thesis' metadata record in the digital repository. Includes bibliographical references.

Typescript. / Thesis (Ph. D.)--University of Hawaii at Manoa, 1990. / Includes bibliographical references (leaves 100-109) / Microfiche. / viii, 109 leaves, bound ill. 29 cm

Thesis (Ph.D.) -- University of Montana, 2008. / Title from author supplied metadata. Description based on contents viewed on June 26, 2009. Includes bibliographical references.

Five transposon Tn5 mutants of bean rhizobia (Rhizobium leguminosarum b.v. phaseoli) and the wild type strain were used in ecological studies to evaluate the efficacy of transposon Tn5 as a phenotypic marker in rhizobia for ecological studies in two Sonoran desert soils. All mutants possessed chromosomal insertions of the transposable element. Survival of each mutant strain was compared to that of the wild type strain under non stress, moisture stress and temperature stress conditions in Pima silty clay loam and Brazil to sandy loam. The genetic stability of Tn5 in terms of transposition of the element within the chromosome and the Tn5 coded antibiotic resistant phenotype was determined in cells recovered throughout the survival period. Under non stress conditions, the viable Tn5 mutant population decreased in size. Two mutants showed significantly (p < 0.01) lower populations than the wild type at the end of 30 days in the silty clay loam. In the sandy loam, four of the five mutant populations were significantly lower than the wild type. Tn5 was genetically stable in both soils. Under moisture stress conditions, the decline of the Tn5 mutant and wild type populations corresponded to a decline in soil moisture content. The finer textured soil afforded more protection to the cells than the coarse textured soil. There were no indications of Tn5 instability under moisture stress. In both soils under temperature stress, sizes of all populations declined rapidly and after 12 days, the mutant cells when screened using the Tn5 coded markers were significantly less in numbers than the wild type indicating a loss of Tn5 coded antibiotic resistance phenotype. There were no significant differences in numbers between wild type and mutant cells when screened using only the intrinsic markers. DNA:DNA hybridizations confirmed that the lack of Tn5 coded antibiotic resistance phenotype was probably not due to a deletion or transposition of the element. Under non stress conditions Tn5 is a useful ecological marker, but each Tn5 mutant has to be evaluated independently under specific environmental conditions to determine the efficacy of Tn5 as an ecological marker.

Includes two journal articles with contributions by the author Bibliography: leaves 145-154

Thesis (Ph.D.)--University of Wollongong, 2009. / Typescript. Includes bibliographical references: leaf 188-214.

Includes two journal articles with contributions by the author / Bibliography: leaves 145-154 / vii, 164 leaves : ill ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Plant Pathology, 1988

Thesis (Ph. D.)--Carleton University, 1992. / Also available in electronic format on the Internet.

The regulation and evolution of the inverted repeat transposable element Tel, found in the nematode Caenorhabditis elegans, was studied. The stability of Tel elements in the N2 strain genome was investigated by cloning seventeen N2 Tel elements. To examine their structural integrity, sixteen cloned N2 Tel elements were restriction mapped and, in the case of some variants, their DNA was partially sequenced. Two restriction site variants, Tcl(Eco).12 and Tcl(Hpa-).9, were found. Tel(1.5).10b had lost 89 bp from one end, while Tcl(1.7).28 contained a 55 bp insertion. Two additional elements, Tcl(0.9).2 and Tcl(0.9).14, had different internal deletions. Each element was about 900 bp in length. The majority of Tel elements cloned from the N2 strain were found to have identical restriction maps. Somatic excision of Tel elements in the N2 genome was demonstrated. Tel elements in N2 are apparently both structurally and functionally intact. Nevertheless, mobilization of Tel elements in the N2 germline is restricted. Two new transposable element families, Barney (also known as TCbl) and TCb2, were discovered in a closely related nematode, Caenorhabditis briggsae due to Tel identity. These two families, distinguished through differential inter-element hybridization, showed multiple banding differences between strains. The open reading frames (ORFs) of Tel and Barney share 71% DNA sequence and 74% amino acid sequence identity. The putative terminus of Barney exhibits 68% identity with the 54 bp terminal repeat of Tel. Partial sequencing of TCb2 revealed that its ORF is equally diverged from Barney and Tel. The basis of the sequence heterogeneity observed in the C. briggsae transposons and not in the C. elegans transposons could be due to either horizontal transfer or alternate paths of divergence. Significant sequence identity was found between Tel, Barney, and HB1 (a transposable element from Drosophila melanogaster) within their coding regions and terminal repeats. These sequence similarities define a subclass of inverted repeat transposable elements inhabiting two different phylla, Arthropoda and Nematoda. / Medicine, Faculty of / Medical Genetics, Department of / Graduate