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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

THE RELATIONSHIP OF BACILLUS SUBTILIS PHYSIOLOGY AND HELICAL STRUCTURE AND ORGANIZATION (MACROFIBER, CELL SURFACE, HELIX HAND INVERSION).

WOLFE, ALAN JEFFREY. January 1985 (has links)
Helix hand inversion exhibited by Bacillus subtilis macrofibers is induced by changes in culture medium composition. The kinetics of this inversion are compared to those of temperature-induced inversions. D-alanine evokes a similar inversion process. The role of left-twist proteins(s), the existence of "memory", and the asymmetry of left to right versus right to left kinetics are confirmed within the context of these inversion regimes. Initiation time of right to left inversions is correlated to degree of pre-shift twist. Evidence is presented suggesting effective twist of the wall is defined by (1) the average of that twist conformation inserted prior to a shift in culture conditions and that of wall inserted following the shift and (2) the location of left-handed material within the wall. A constant 50 minute delay is observed before initiation of left to right inversions, irregardless of twist. Evidence is presented for a protein in the left to right inversion process. A classification system of macrofiber phenotypes based upon hand and degree of structural organization has been established. Three major classes are identified. Subclasses are shown to be distinguishable. Isotwist phenotypes of seven strains are defined upon a matrix of temperature and medium composition. These plots reveal a fundamental pattern of hand and organization that is present in each of the strains studied. The polarity of the four axes, the range of attainable twist conformations, and the existence of a right-hand maximum in the 12.5% SPl domain remain virtually constant. Major variations include extent of a disorganized band and/or the shifting of conformational range either left or right. Several mutants were transformed into A734, a strain that produces the tightest structures at all four matrix corners. Multiple mutations are responsible for the phenotypes of several strains. Evidence is presented for single genes that express as extreme left-handedness and stress at high temperature, swelling and stress in TB at high temperature, and reduction in structural organization produced in high TB content at low temperature.
2

Architecture of the plant extracellular matrix

McCann, Maureen C. January 1990 (has links)
No description available.
3

Investigating the role of bacterial cell envelope components and host peptides in the Sinorhizobium meliloti-legume symbiosis

Haag, Andreas F. January 2011 (has links)
Sinorhizobium meliloti forms a symbiosis with Medicago species of legumes. Within the legume root nodules, S. meliloti differentiates into a bacteroid, which fixes atmospheric nitrogen into ammonia for the legume. The legume produces hundreds of nodule-specific cysteine-rich (NCR) peptides, which mediate bacteroid differentiation. The S. meliloti BacA protein was the first bacterial factor identified to be essential for bacteroid development. BacA sensitises S. meliloti to certain antimicrobial peptides and influences the modification of the bacterial lipopolysaccharide (LPS) with a very-long-chain fatty acid (VLCFA). Therefore, it is thought that either the peptide uptake function or the role of BacA in LPS VLCFA decoration could be essential for survival of S. meliloti within the legume. In this PhD project, a role for BacA in the response of S. meliloti towards NCR peptides was investigated. It was determined that BacA protects S. meliloti from NCR-induced cell death. Furthermore, it was found that the structure and composition of the LPS plays a key role in the response of S. meliloti to NCR peptides. It was also shown that the peptide uptake function of BacA was conserved among different rhizobia. The role and biosynthesis of the LPS VLCFA in bacteroid development was also explored. It was determined that the acyltransferase but not the acyl-carrier-protein, was essential for the biosynthesis of VLCFA modified LPS in planta. Six genes, located in a gene cluster were proposed to be involved in the LPS VLCFA biosynthesis in rhizobia and my research found that this was the case. The outcome of this research has provided important insights into the mechanism of prolonged bacterial-host infections and the biosynthesis of unusual lipids.
4

Mushroom cell wall architecture: composition and structure of cell wall components in different developmental stages of Pleurotus tuber-regium. / CUHK electronic theses & dissertations collection

January 2013 (has links)
Chen, Lei. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves 142-161). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.
5

Development and application of a new method for analysing plant cell walls

Li, Xiaofei January 2012 (has links)
No description available.
6

Identification of proteins involved in cell wall synthesis by integration of high-throughput technologies

Segura, Marcelo Patricio January 2012 (has links)
No description available.
7

A biophysical examination of the tripartite layer of the cell of a gram-negative bacterium.

Forge, Andrew. January 1971 (has links)
No description available.
8

Studies on the lipopolysaccharide of a marine bacterium.

DiRienzo, Joseph M. January 1976 (has links)
No description available.
9

Biochemical studies on cell envelope and its associated enzymes in normal and morphological mutants of Escherichia coli.

Singh, Akhand P. January 1972 (has links)
No description available.
10

Genetic manipulation of the cell wall composition of sugarcane /

Bekker, Jan P. I. January 2007 (has links)
Dissertation (PhD)--University of Stellenbosch, 2007. / Bibliography. Also available via the Internet.

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