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Protein synthesis is an essential process for all living organisms and is an effective major target for current antibiotics. Elongation factor Tu (EF-Tu) is a highly conserved and essential protein that functions during protein synthesis. EF-Ts interacts with EF-Tu to help maintain a functionally active state of EF-Tu required for cell growth. Although EF-Ts is essential for Escherichia coli, its sequence is poorly conserved. LepA is a highly conserved protein within bacteria and has a similar structure to EF-Tu. In spite of this, LepA has been shown to be non-essential under ideal conditions and the function of LepA still remains elusive. An analysis on the structurally unique aspects of LepA, EF-Tu and EF-Ts was performed here in an effort to gain an understanding on the functions of these proteins. This knowledge, in combination with their unique structural components will provide important tools in developing new and effective antibiotics. / xiii, 177 leaves : col. ill. ; 29 cm

ROP GTPases are crucial regulators of pollen tube growth. The Rop GTPase family in maize consists of nine known rop genes, ropl-rop9. A subset of these genes (rop2, rop8, and rop9) are expressed in pollen. The rop2 and rop9 genes are a highly conserved duplicate gene pair of ancient origin. The rop2/rop9 duplicate gene pair displays differential expression in mature and germinated pollen, suggesting different roles for the genes in the process of male gametophyte development. To explore ROP2 function in maize, five Mutator transposon insertions in the rop2 gene were isolated (rop2::Mu alleles). I showed that three of the rop2::Mu alleles displayed reduced transmission through the male and were associated with reduced levels of ROP2-mRNA. Interestingly, the rop2::Mu male-specific transmission defect was apparent only when wild-type pollen was also present, an indication that the mutation reduces the competitive ability of the rop2 gametophytes. Dual pollination and pollen mixing experiments indicated that this competitive disadvantage is expressed by the majority of the mutant gametophytes, and that expression of the phenotype is associated with a delay in the ability to accomplish fertilization. Using the waxy phenotypic marker (linked to rop2 via a reciprocal translocation) to distinguish between rop2::Mu and wild-type pollen derived from heterozygous plants, I demonstrated that the delay is associated with a defect in early progamic development (i.e, germination and early pollen tube growth). The defect was detectable in vivo as early as 15 minutes after pollination. However, quantitative measurements provided no indication that the rop2 mutation affects pollen tube growth in the style. Finally, investigations focusing on the final stages of pollen function raise the possibility that a defect in the very last stages (i.e. either pollen tube guidance through the micropyle to the egg sac, or fertilization of the egg sac) may also contribute to the rop2 mutant delay. This work provides direct in vivo evidence confirming a role for Rop in male gametophyte development, and is the first study to demonstrate a role for Rop in the early stages of post-pollination gametophytic function. / Graduation date: 2005

Thesis (doctoral)--Karolinska Institutet, Stockholm, 1988. / Extra t.p. with thesis statement inserted. Includes bibliographical references.

Thesis (Ph. D.)--University of California, San Diego and San Diego State University, 2000. / Includes bibliographical references (leaves 118-135).

Thesis (Ph. D.)--Duke University, 2007. / Includes bibliographical references.

Thesis (Ph. D.)--Ohio State University, 2007. / Title from first page of PDF file. Includes bibliographical references (p. 146-165).

Modern studies on charge transfer reaction and conductivity measurements of DNA have shown that the electrical behavior of DNA ranges from that of an insulator to that of a wide bandgap semiconductor. Based on this property of DNA, a metal-semiconductor-metal photodetector is fabricated using a self-assembled layer of deoxyguanosine derivative (DNA base) deposited between gold electrodes. The electrodes are lithographically designed on a GaN substrate separated by a distance L (50nm < L < 100nm). This work examines the electrical and optical properties of such wide-bandgap semiconductor based biomaterial systems for their potential application as photodetectors in the UV region wherein most of the biological agents emit. The objective of this study was to develop a biomolecular electronic device and design an experimental setup for electrical and optical characterization of a novel hybrid molecular optoelectronic material system. AFM results proved the usage of Ga-Polar substrate in conjugation with DG molecules to be used as a potential electronic based sensor. A two-terminal nanoscale biomolectronic diode has been fabricated showing efficient rectification ratio. A nanoscale integrated ultraviolet photodetector (of dimensions less than 100 nm) has been fabricated with a cut-off wavelength at ~ 320 nm.

No description available.

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.