Direct Infusion (DI) Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry (MS) is becoming a popular measurement platform in metabolomics. This thesis aims to advance the data processing and analysis pipeline of the DI FT-ICR based metabolomics, and broaden its applicability to a clinical research. To meet the first objective, the issue of missing data that occur in a final data matrix containing metabolite relative abundances measured for each sample analysed, is addressed. The nature of these data and their effect on the subsequent data analyses are investigated. Eight common and/or easily accessible missing data estimation algorithms are examined and a three stage approach is proposed to aid the identification of the optimal one. Finally, a novel survival analysis approach is introduced and assessed as an alternative way of missing data treatment prior univariate analysis. To address the second objective, DI FT-ICR MS based metabolomics is assessed in terms of its applicability to research investigating metabolomic changes occurring in liver grafts throughout the human orthotopic liver transplantation (OLT). The feasibility of this approach to a clinical setting is validated and its potential to provide a wealth of novel metabolic information associated with OLT is demonstrated.

The research presented here constitutes the latest advances in the use of the Antarctic bivalve mollusc Aequiyoldia eightsii as a sclerochronological proxy for Antarctic coastal waters. A. eightsii has the potential to provide annually-resolved records for the Antarctic shallow waters beyond the beginning of the instrumental record. A comprehensive study of A. eightsii shell growth was carried out, which highlighted two ontogenetic trends: i) negative exponential and ii) a quasi-cyclic trend of a period of nine years, which may relate to allocation of energetic resources. Using crossmatching techniques, four chronologies from adjacent locations near Rothera Station (West Antarctic Peninsula, WAP) and an additional chronology from historical samples collected near Signy Station (South Orkney Islands, SOIs) were developed. Additionally further work on a pre-existing chronology from the SOIs is presented. Instrumental records and climatic indices were analysed to determine environmental variability and the factors controlling shell growth. Seawater temperature and fast-ice duration seem to be the main environmental drivers of A. eightsii shell growth. Shell growth of South Cove (WAP) specimens seem to better reflect to environmental conditions recorded in the Rothera Biological Time Series. Stable oxygen and carbon isotope (δ18O and δ13C) records were developed from shell carbonate material; these showed sub- and inter-annual variability and all specimens showed similar trends in δ18Oshell and δ13Cshell, with the exception of a deep-collected specimen of the SOIs, which showed much reduced interannual variability and a stronger δ13Cshell negative trend with ontogenetic age. Additionally, stable isotope fractionation depending anatomical part of the shell (anterior, ventral and posterior) was studied, which showed intra-increment variability in δ18Oshell and δ13Cshell. The present work constitutes a comprehensive calibration of A. eightsii as a sclerochronological proxy for Antarctic shallow coastal waters, which will help to expand our understanding of climate trends in the region.

The contribution of store-operated calcium entry (SOCE) in the response of human sperm to progesterone, a steroid secreted from the cumulus cells surrounding the oocyte, has not yet been elucidated. The aim of this study was to investigate the presence of SOCE proteins in human sperm and examine the effects of pharmacological modulation of SOCE on the progesterone-induced biphasic intracellular calcium concentration ([Ca\(^{2+}\)]i) response. STIM (stromal interacting molecule) and Orai, proteins of the SOCE system were detected in human sperm in a similar location to intracellular Ca\(^{2+}\) stores. 2-aminoethyldiphenyl borate (2-APB; SOCE modulator) altered SOCE in human sperm in a bimodal manner as seen in other cell types. Furthermore, 5\(\mu\)M 2-APB potentiated the initial progesterone-induced [Ca\(^{2+}\)]i transient within the neck and midpiece, but not in the flagellum. In the sustained phase of the progesterone-induced [Ca\(^{2+}\)]i response both 5\(\mu\)M 2-APB and 10\(\mu\)M loperamide (another modulator of SOCE) potentiated the [Ca\(^{2+}\)]i response. Higher doses of 2-APB (50-200\(\mu\)M) didn’t potentiate the transient [Ca\(^{2+}\)]i and inhibited the sustained response consistent with reported actions on SOCE. Ryanodine receptors were localised to the neck/midpiece region which suggested that they may mobilise intracellular Ca\(^{2+}\) stores in response to progesterone, leading to activation of STIM/Orai and initiating SOCE.