Among the South African Thysanura, the order Lepismatoidea has spread over the whole sub-continent, while all except one species of the order Machiloidea are confined to the discontinuous forest belt which lies below the escarpment of the inland plateau. The Machiloidea are not , however, strictly confined to the actual forests within their geographical region, some species invading regions of considerable aridity. Investigations on the ecology, water relations and orientation behaviour of a representative species of each order have been carried out. These have revealed that: (i) the physical conditions in the typical niche of the Machiloidea are extremely stable, whereas those in the habitat of the Lepismatoidea are subject to some considerable fluctuation. (ii) the Lepismatoidea are more resistant to desiccation than the Machiloidea; in both cases this resistance is due in part to physical barriers in the cuticle and partly to an active metabolic process. (iii) the Machiloidea rely on their eversible vesicles, situated on the abdominal coxosternites, for the uptake of water which cannot be drunk, such as a thin film of water or soil capillary water. (iv) the Lepismatoidea are able to absorb water from a subsaturated atmosphere. (v) the behavioural responses of both in respect of humidity, temperature, light and gravity, are such as to keep them in conditions within the range of their physiological limitations. From these results it is concluded that the Machiloidea can survive outside the shelter of forests, provided that water is readily available in some form in which it can be absorbed by the animals. The general implications of the results are such as to permit the erection of an hypothesis explaining the distribution of the Thysanura in South Africa in terms of t he availability of wate. The results also lead to speculations on the evolution of the Pterygota.

The recognition of small organic compounds and metabolites is essential for living systems, enabling the cell to sense environmental stimuli and respond appropriately. Developing quantitative models of living systems which can incorporate these environmental stimuli would accordingly benefit from comprehensive mapping of interactions between proteins and small molecules of interest. While high-throughput experimental methods provide a wealth of interaction data, the scale of chemical space currently precludes comprehensive enumeration of protein-compound interaction space. Computational methods can help to bridge this gap by inferring proteome-scale protein-compound interactomes, elucidating structural features within protein families which mediate specificity of binding to specific small molecules, and inferring the affinity of binding for specific protein-compound interactions. In this thesis, we attempt to use, and in some cases develop, methods to study protein-compound interactions at these three scales. First, we describe recent work in extending our structure-based algorithm for predicting protein-compound interactions throughout the proteome to include a wider array of small molecules. We demonstrate that this method performs comparably to existing methods and describe an online database storing the results of this analysis. We also report several case studies illustrating how this database can be used along with cautionary vignettes indicating areas where the method fails and directions for future improvement. We subsequently analyze druggable pockets occurring within protein-protein interfaces (PPIs) to assess whether they are less structurally conserved than analogous pockets of conventional drug sites. We find that PPI interfacial pockets are associated with fewer expected off-targets than conventional drug sites, however that this finding is specific to individual protein families, rather than a general feature of interfacial PPI pockets. Finally, we use Free Energy Perturbation to predict the binding affinity of an array of small volatile odorants with an olfactory receptor from the jumping bristletail, Machilis hrabei, as well as attempt to further optimize the system in order to study the effects of mutating receptor binding site residues on binding affinity to its active ligands.