No description available.

Disease problems in crop plants are still a major threat to the agro-industry worldwide. Various strategies have been developed and evaluated in recent years. One strategy is to use naturally-occurring antipathogen factors such as lysozymes and chitinases in transgenic plants. In the present study, transgenic plants containing chick-egg white lysozyme (Lys 75) have been evaluated for lysozyme production in planta, subcellular localisation, and resistance to some potato pathogens, including Phytophthora infestans and Erwinia carotovora subsp. atroseptica, the two major potato pathogens worldwide. In addition, the evaluation of resistance was also undertaken for transgenic plants carrying other naturally-occurring antipathogen factors including a bean chitinase gene (BCH 35) and a snowdrop lectin gene (GNA 74). In order to accurately quantify the lysozyme production in Lys 75 plants, the turbidimetric lysozyme enzyme assay was optimised. Also, a modified substrate for the enzyme has been developed by covalently linked the Micrococcus lysodeikticus cell wall with a dye, remazol brilliant violet 5R to enable a colorimetric assay of the enzyme. In order to quantitatively assess resistance levels of the transgenic plant, a new method (leaf-bridge bioassay) for conducting and evaluating resistance in planta has been developed. All transgenic plants in tissue culture were tested for resistance using this technique. Evaluation of the progress of infection in detached leaves of Lys 75 showed that lysozyme gave some degree of protection against the bacterial pathogen, Erwinia carotovora subsp. atroseptica and the fungal pathogen, Fusarium sulphureum. Analysis of intercellular fluid from the Lys 75 leaves showed that more than 80% of the total lysozyme expressed in the leaf was located in the intercellular space which is a strategic place to combat pathogen attack. In contrast, the levels of protection in BCH 35 plants were relatively low compared with Lys 75. The progress of infection was delayed in BCH 35 leaves challenged with F. sulphureum only. No resistance at all was observed in GNA 74 to all the pathogens used. All the transgenic potato lines were susceptible to P. infestans. Recently, a new strategy to combat disease problems has been suggested based on a 'durable resistance'. Potato variety Stirling' which shows durable resistance in the field has been used to study the early biochemical and molecular events during elicitation of 'Stirling' cell suspension cultures with an elicitor mix derived from infective units of a compatible strain of P. infestans. For comparison, an elicitor mix from an incompatible strain of P. infestans was also prepared and used. The mixed elicitor comprising zoospore extract, culture filtrate and mycelium homogenate induced defence responses in 'Stirling' cell suspension cultures as judged by the increase in PAL enzyme activity. PAL activity in 'Stirling' ceUs elicited with an elicitor mix derived from an incompatible strain of P. infestans was twice the activity in the compatible interaction. The peak levels in both types of interaction were at 6 h post-elicitation. An oxidative burst was demonstrated also in both types of interactions indicated by rapid release of H(_2)O(_2) into the culture medium. The H(_2)O(_2) level peaked at 2 h post-elicitation in both interactions before being reduced to its normal level at 4 h. The H(_2)O(_2) released during incompatible interaction was twice the levels monitored in the compatible. A subtracted cDNA library of differentially expressed mRNAs during elicitation of 'Stirling' cell suspension cultures with the elicitor mix from a compatible strain of P. infestans was constructed using suppression subtractive hybridisation. Two cDNA clones, STS 42 and STS 52, relevant to the present study were identified and characterised. STS 42 showed high degree of similarity to potato leucine aminopeptidase gene which is induced in response to wounding. Gene expression studies using RT-PCR showed that the mRNA levels of STS 42 increased gradually throughout the 18 h elicitation. STS 51 was identified as a member of the ribonuclease T2 histidine proteins. It showed some degree of similarity to plant ribonucleases involved in self-incompatibility reactions during pollination. It has a site for tyrosine kinase phosphorylation at the hydrophilic region of the sequence and could possibly be involved in phosphorylation during signal transduction. mRNA levels of STS 51 were increased during the first 12 h of elicitation.

No description available.

Proefschrift--Utrecht. / "Stellingen": iii p. at end.

Proefschrift--Utrecht. / "Stellingen": iii p. at end.

In the thesis I test the hypothesis that Late Old Japanese (LOJ) is not, as has been claimed by a number of scholars, a language that is innately "vague", but that it is capable of conveying meaning clearly. To prove this I analyse the text of the Genji Monogatari in a number of ways. I study the usage of honorifics in the text and the relationship between honorific usage and court rank. I show that honorific usage very often obviates the need for grammatical subjects and objects, and where honorifics or the context are not sufficient, the author introduces subjects to clarify the meaning of the text. Furthermore, I demonstrate that over brief sections of text, one character might be "tagged" with a particular honorific in order to identify them. Status at the Heian court was determined by court rank, and the higher a person's rank, the more honorifics had to be used. I investigate how characters could be identified when several people of similar ranks interacted. This will show that use by the author of the category of theme as well as occasional subjects serves to identify characters. I examine the applicability of the phenomenon of switch reference to LOJ, attempting to determine how far it may have enabled the ommission of grammatical subjects, and where LOJ presents problems for the canonical account of switch reference. I examine syntactic differences between narrative and quotation, and excerpts where there are differences over where quotations begin, and cases where different characters' quotations follow each other directly with no overt marking to separate them. Finally, I study personal reference, covering the link between characters' sobriquets and the type of scene in which they are appearing, and the usage of personal pronouns and demonstratives in the text.

No description available.

No description available.

In this thesis various physicochemical factors which determine the characteristics of latex agglutination immunoassays are examined. A model of antibodies reacting with antigen (bovine serum albumin; BSA) adsorbed to the surface of polystyrene latex (PSL) beads was examined. The adsorption studies of BSA to PSL showed that the mass of BSA adsorbed at saturation depends on the type of polystyrene latex. Latexes with highly hydrophobic surfaces adsorbed more BSA molecules than those with lower hydrphobicity. Desorption studies showed that latexes that maximize adsorption lost the lowest fraction of their bound BSA molecules following extensive buffer wash. Partial desorption of BSA from PSL was achieved by the addition of detergent, whereas the addition of more BSA molecules or other macromolecules such as PEG or IgG did not displace the adsorbed BSA molecules. Examination of the material removed from the surface of the latexes by SDS-PAGE analysis showed that the composition of the adsorbed layer was enriched in the higher molecular weight oligomers of BSA, relative to their concentrations in the stock solution. A model in which adsorbed protein is assumed to undergo a polymerization reaction provides a general explanation of the observed results. Studies of polyclonal antibody (anti-BSA IgG) binding to antigen-coated PSL showed that the surface concentration of bound antibody depends on the surface concentration of antigen on the latex particles and on the availability of PSL surface area not occupied by antigen. Analysis of shear induced aggregation results show that for low surface coverage of latex particles by protein antigen in stable suspension, relatively low concentrations of specific antibodies are required to cause agglutination. Increasing surface density of antigen requires significantly higher concentrations of specific antibodies to produce agglutination. For a given surface coverage of antigen, results show that increasing the shear rate decreases the antibody concentration necessary to produce a given degree of agglutination. A remarkable structure formation and long range ordering exhibited by floes of latex coagulating in salt under intermediate shear rates was observed. This structure formation was not observed during antibody-induced agglutination under shear. / Science, Faculty of / Chemistry, Department of / Graduate

Thesis (Ph.D.)--Boston University / How Emy Lyon became Emma Hamilton (1765-1815) through the creation, display, and circulation of painted portraits, portrait prints, letters, and architectural imagery is the focus of this dissertation. In it, I make four main claims. First, Emma's introduction to the rituals and rewards of genteel female behavior began in George Romney's studio, and sitting for portraits was an educational process that continued throughout her life. Second, Emma's education continued during her residency in Naples under the care and direction of Sir William Hamilton, and the imagery from this period participates in Emma's transformation from Sir William's mistress to his wife. Portraits and letters after the 1791 marriage advertised traits that Sir William's social circle would find desirable and helped to justify her elevated position. Third, Emma's relationships with powerful women were as essential to her self-fashioning as her relationships with men. Elisabeth Vigée-Lebrun, Angelica Kauffman, and Queen Maria Carolina of Naples served as important role models for Emma, and opportunities for fame and power resulted from her association with them. Finally, upon her return to England in 1800, Emma sought to manipulate the architecture, decoration, and visual representations of Nelson's country home to showcase her virtuous conduct. Throughout the dissertation, I aim to suggest that Emma contributed to the fashioning of her identity and show the ways in which her involvement increased during her lifetime. The other people who contributed to such fashioning of her identity--from artists to lovers to royalty--necessarily play a part in this study. How Emma adapted and responded to the situations that others created is central to my analysis and understanding of self-fashioning. The dissertation ultimately proposes that becoming Emma Hamilton was a complex, life-long process with both constructive and destructive consequences.