Fragments of a map ; an exegesis concerning the novel, Fragments of a map

The novel explores the journey towards completion for two women and, through its concerns and structure, plays with the notion of research in the creative arts. The exegesis comments upon the concerns of the novel, and the writing and research processes.

Dehydration and the natriuretic peptide system in the toad, Bufo marinus

The natriuretic peptide system is a family of related proteins that in humans function to reduce blood pressure and blood volume. However, in amphibians the function is less well understood. This thesis demonstrates that the amphibian, Bufo marinus, possesses a well-developed natriuretic peptide system that is capable of responding to changes induced by dehydration.

Natriuretic peptide receptor signalling in the gills of fishes

Natriuretic peptide hormones exert their effects by binding to receptor proteins and activating cellular responses. Fish gills interface with the aquatic environment. Therefore, natriuretic peptide receptor activity in gills from marine and freshwater fishes was examined. The potencies of natriuretic peptides were compared and a novel cellular response was identified.

Identification, distribution and expression of natriuretic peptide receptors in trout

This study identified cell receptors for trout natriuretic peptide hormone. These hormones protect the heart and maintain fluid balance. Receptor populations on cells depend on whether the animal lives in freshwater or saltwater. Receptors are widely distributed and different receptor types perform different tasks. Their original evolutionary role is suggested.

The natriuretic peptide system of the heart and central blood vessels of the toad, Bufo marinus

This research has established the presence of a natriuretic peptide system in the cardiovascular system of the toad, Bufo marinus. The presence of atrial natriuretic peptide mRNA and the peptide itself were shown in the heart which does not contain natriuretic peptide receptors in contrast to the large arteries and veins. In arteries these receptors mediated vasodilation. Atrial natriuretic peptide released from the heart may act on large arteries to regulate blood flow, but the action does not target the heart.

Natriuretic peptide regulation of the kidney and urinary bladder in the cane toad, Bufo marinus

The natriuretic peptide system of mammals is important in the control of blood volume but its function in non-mammalian animals is unclear. This study identified a functional natriuretic peptide system in an amphibian and showed that the hormones are involved in the control of fluid balance.

Clustering of Th cell epitopes on exposed regions of HIV envelope despite defects in antibody activity

A long-standing question in the field of immunology concerns the factors that contribute to Th cell epitope immunodominance. For a number of viral membrane proteins, Th cell epitopes are localized to exposed protein surfaces, often overlapping with Ab binding sites. It has therefore been proposed that Abs on B cell surfaces selectively bind and protect exposed protein fragments during Ag processing, and that this interaction helps to shape the Th cell repertoire. While attractive in concept, this hypothesis has not been thoroughly tested. To test this hypothesis, we have compared Th cell peptide immunodominance in normal C57BL/6 mice with that in C57BL/6MT/MT mice (lacking normal B cell activity). Animals were first vaccinated with DNA constructs expressing one of three different HIV envelope proteins, after which the CD4 T cell response profiles were characterized toward overlapping peptides using an IFN- ELISPOT assay. We found a striking similarity between the peptide response profiles in the two mouse strains. Profiles also matched those of previous experiments in which different envelope vaccination regimens were used. Our results clearly demonstrate that normal Ab activity is not required for the establishment or maintenance of Th peptide immunodominance in the HIV envelope response. To explain the clustering of Th cell epitopes, we propose that localization of peptide on exposed envelope surfaces facilitates proteolytic activity and preferential peptide shuttling through the Ag processing pathway.